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Item 6a. Introduce an Ordinance to Amend Title 13, Chapter 13.12 of the Municipal Code to Establish a new Underground Utility District and provide direction on the Prado Interchange Project and Prado Creek Bridge Replacement Project
CouncilAgenda • • CIS � Department: Cost Center: For Agenda of: Placement: Estimated Time FROM: Scott Collins, Assistant City Manager Prepared By: Matt Horn, Major City Projects Manager Item 6a Public Works 5009 8/4/2026 Public Hearing 120 mins SUBJECT: INTRODUCE AN ORDINANCE TO AMEND TITLE 13, CHAPTER 13.12 OF THE MUNICIPAL CODE TO ESTABLISH A NEW UNDERGROUND UTILITY DISTRICT COMPRISING THE LIMITS OF THE PRADO INTERCHANGE PROJECT AND PROVIDE DIRECTION ON THE PRADO ROAD INTERCHANGE PROJECT AND PRADO CREE RECOMMENDATION Prado Road Interchange Recommendations 1. Introduce a draft Ordinance entitled, "An Ordinance of the City Council of the City of San Luis Obispo, California, amending Section 13.12.040 of the San Luis Obispo Municipal Code to Establish a New Underground Utility District 17" (Attachment A & B); and 2. Receive and file the Final Value Analysis, Draft Bridge Type Selection and Wall Type Selection Reports which provides the technical basis for the Supplemental Project Report and final design development (Attachment D, E & F); and 3. Authorize the Assistant City Manager to approve and execute the final Caltrans Supplemental Project Report (SPR) (Attachment G) upon completion of the remaining technical appendices, provided no substantive changes are made to the project scope, purpose, or core recommendations; and 4. Select an Aesthetic Theme (Attachment H) for the Interchange Project: a. "Figure 4 — Base Theme"; or b. "Figure 5 — Mission Theme"; or c. "Figure 6 — Modern Mission Theme"; and 5. Provide direction on gateway branding by either: a. Including City branding lettering ("San Luis Obispo") to establish a regional gateway landmark; or b. Advancing a more heavily landscaped area instead of City branding; and 6. Direct staff to evaluate a future Class I shared -use path along Elks Lane during the next update to the City's Active Transportation Plan and, where feasible, acquire the necessary right-of-way in conjunction with the Prado Road Interchange Project to preserve the opportunity for future implementation; and Prado Creek Bridge Recommendations Page 121 of 1059 Item 6a 7. Receive and file the Preliminary Value Analysis Study (Attachment 1) and approve Value Analysis implementing design alternatives 1.0, 3.0, 4.0, 5.0, and 6.0 and not implementing design alternatives 2.0 and 7.0; and 8. Authorize the Finance Director to make the following budget revisions: a. Decrease the project's appropriation of Federal Earmark grant funds from $4.130 million to $2.065 million to resolve an accounting duplication; and b. Decrease the projects appropriation of Federal Highway Bridge funds from $6.0 million to $0 to more appropriately align the funds with the anticipated reception timeframe; and 9. Adopt a Draft Resolution entitled, "A Resolution of the City Council of the City of San Luis Obispo, California, Authorizing Budget Adjustments for the Prado Creek Bridge Replacement Project." (Attachment J) Prado Creek Bridge & Prado Road Interchange Projects Recommendation 10. Adopt a Draft Resolution entitled, "A Resolution of the City Council of the City of San Luis Obispo, California, Authorizing Submittal of Grant Applications for the Prado Road Interchange Project and Prado Creek Bridge Replacement Project, and requiring Council Appropriation upon Grant Award." (Attachment K) REPORT -IN -BRIEF This report presents several policy and implementation actions necessary to continue advancing the Prado Road Interchange Project (Interchange Project) and Prado Creek Bridge Replacement Project (Bridge Project) through final design and toward construction. For the Interchange Project, Council is being asked to establish an Underground Utility District, receive the completed Value Analysis and draft Bridge and Wall Type Selection Reports, authorize approval of the final Supplemental Project Report upon completion of technical review, approve the recommended interchange aesthetic theme and provide direction on gateway branding and a future Class I shared -use path along Elks Lane. For the Bridge Project, Council is being asked to consider receiving the Preliminary Value Analysis Study, approving the recommended design refinements to reduce project costs while maintaining project functionality and performance, and authorizing budget revisions to grants to align funding appropriations with authorized reimbursements and eligible funding sources. Implementation of the recommended Value Analysis alternatives is estimated to reduce construction costs by approximately $5 million, resulting in an estimated construction cost of approximately $23 million in 2026 dollars. Collectively, these actions establish key policy direction for both projects improving long- term project affordability and allowing the City to continue advancing two high -priority transportation infrastructure projects. Page 122 of 1059 Item 6a POLICY CONTEXT The Prado Road Interchange Project (Interchange Project) and Prado Creek Bridge Replacement Project (Bridge Project) are legacy transportation investments that implement the City's adopted vision for the Prado Road corridor. Together, these projects advance the City's Major City Goals for Infrastructure and Sustainable Transportation, Housing and Neighborhood Livability, and Open Space, Climate Action, and Resilience. In addition, these projects directly implement numerous policies contained within the General Plan Land Use and Circulation Element (LUCE) and the 2021 Active Transportation Plan (ATP). The LUCE identifies the Interchange Project as "Project 19" and identifies improvements to the Prado Road corridor on both sides of US 101 as Projects 1 and 2. While the LUCE does not separately identify the Bridge Project, the project is located within the Prado Road Extension East corridor identified as Project 2. See pages 2-31 through 2-34. The ATP identifies both the Interchange Project and Bridge Project as components of the Tier 1 bicycle and pedestrian network, as shown on Figure 27 on page 134. Tier 1 projects represent the City's highest priority active transportation improvements and are identified as having the greatest potential to increase bicycle and pedestrian travel. The General Plan identifies Prado Road as a critical east -west transportation arterial serving motorists, transit, emergency responders, bicyclists, and pedestrians. The corridor is planned to provide continuous, high -quality multimodal connectivity between South Higuera Street, US 101, Dalidio Drive, San Luis Ranch, and future development areas to the east. Both the Land Use and Circulation Element and the Active Transportation Plan recognize the historical lack of east -west connectivity across the southern portion of the City. The coordinated Prado Road improvements are intended to improve safety and operations for all users. They will provide modern roadway geometry, safer intersections, improved bicycle and pedestrian facilities, and more direct connections across US 101. The projects will also strengthen emergency and public -safety response by providing additional, more reliable east -west access between neighborhoods, employment areas, public facilities, and the regional highway system. By creating a new connection across US 101 and improving the surrounding interchange, bridge, and roadway network, the projects are expected to distribute traffic more effectively, reduce circuitous travel, and relieve operational pressure on the adjacent Los Osos Valley Road and Madonna Road interchanges. Improved trafficflow will help reduce vehicle queuing at freeway ramps and interchange intersections, which in turn supports safer highway operations by reducing the potential for queue -related conflicts, sudden braking, and spillback onto US 101. Together, these improvements advance regional mobility, multimodal safety, emergency access, and the infrastructure needed to support long-term community growth. Page 123 of 1059 Item 6a Environmental documents prepared for the San Luis Ranch, Avila Ranch, Froom Ranch, and Margarita Area Specific Plans identify the Prado corridor infrastructure as necessary to address cumulative regional circulation impacts. Both the Interchange and Bridge projects are reimbursable facilities within the City's Citywide Transportation Impact Fee (TIF) Program, allowing incoming development to contribute its proportional share toward construction. Furthermore, the San Luis Ranch Development Agreement stipulates dedicated financial contributions explicitly restricted to the Interchange Project. An Underground Utility District is a defined geographic area established by City Council ordinance in which existing overhead electric, telecommunications, and related utility facilities are required to be converted to underground service. Chapter 13.12 Underground Utilities, of the San Luis Obispo Municipal Code establishes the mechanism for creating these districts. Chapter 13.12.030 requires the City Council to adopt an ordinance and the City to formally notify affected property owners before overhead utilities may be converted to underground service. The City has a long-standing policy of undergrounding overhead facilities where practical and has previously established sixteen underground utility districts. More information on the proposed Underground Utility District can be found further into this report in Section "New Underground Utility District 17 for the Interchange Project". DISCUSSION Background Prado Road is planned to be one of the City's primary east -west transportation corridors and serves as a critical connection between residential neighborhoods, employment centers, regional commercial destinations, industrial areas, public facilities, and US 101. The corridor accommodates local and regional traffic, designated truck routes, emergency response, transit, bicyclists, and pedestrians. Recognizing its importance, the City's General Plan Circulation Element identifies Prado Road as a key arterial necessary to improve community connectivity and support planned growth in the southern portion of San Luis Obispo. The General Plan further identifies three complementary Capital Improvement Plan projects that together will establish a continuous multimodal transportation corridor extending from Broad Street on the east to Madonna Road on the west. These coordinated projects include: 1. Bridge Project: Replacement of the existing Prado Road bridge over San Luis Obispo Creek with a wider bridge capable of accommodating future traffic volumes while providing enhanced bicycle and pedestrian facilities. The project also reconstructs the Prado Road/South Higuera Street intersection. 2. Interchange Project: Construction of a new Prado Road overcrossing of US 101, reconstruction of the northbound interchange ramps, addition of a northbound auxiliary lane between Prado Road and Madonna Road, realignment of Elks Lane, and widening of Prado Road. Page 124 of 1059 Item 6a 3. Prado Road Extension Project: Future extension of Prado Road from its current eastern terminus to Broad Street (State Route 227), creating a continuous east - west arterial connection and improving access to future development areas identified in the General Plan. While this project is dependent upon future development and right-of-way acquisition, it will ultimately complete the eastern segment of the Prado Road corridor. nrcu,eo o, \ N Slone dgJ 0, o \ S� prod .. 'kll" o Fkre�Sjan .000 S�arss Cmm�i�� 0 500 1,000 2.000 Feet Figure 1 — Related Project Vicinity Map Interchange Project The Interchange Project is the largest and most complex transportation improvement planned within the Prado Road corridor. The project has been under development for more than two decades and is sponsored by the City of San Luis Obispo in partnership with the California Department of Transportation (Caltrans). Project development has included completion of a Project Study Report (PSR), Project Approval and Environmental Document (PA&ED), environmental clearance under both the California Environmental Quality Act (CEQA) and National Environmental Policy Act (NEPA), and approval of the Project Report authorizing advancement into the Plans, Specifications and Estimates (PS&E) phase of design. The project addresses long-standing transportation deficiencies resulting from the absence of a continuous east -west crossing between the Los Osos Valley Road and Madonna Road interchanges. By providing a direct connection across US 101, the project will improve circulation throughout southern San Luis Obispo, reduce vehicle travel distances, relieve congestion at adjacent interchanges, improve multimodal connectivity, enhance emergency response routes, and provide the transportation infrastructure Page 125 of 1059 Item 6a necessary to accommodate planned residential and commercial growth identified in the General Plan. On September 5, 2023, the City Council reviewed multiple interchange alternatives, selected the Preferred Alternative, and approved the Project Report for advancement through the Caltrans project delivery process. Subsequently, on February 18, 2025, the City Council awarded the PS&E design contract to Consor Engineering to advance final project design. During that meeting, the Council also expressed concern regarding the project's estimated cost, the potential need for significant debt financing, and the importance of pursuing additional regional, state, and federal funding. To address these concerns, the Council supported implementation of a comprehensive Value Analysis during final design to identify opportunities to reduce construction costs while maintaining project performance and long-term functionality. On November 4, 2025, the City Council reviewed the preliminary Interchange Project Value Analysis and approved a preferred set of conceptual, cost -saving design refinements. Bridge Project Immediately east of the Interchange Project, the City is advancing the Bridge Project. The Bridge Project will replace the existing Prado Road bridge over San Luis Obispo Creek while improving safety, multimodal access, and utility reliability. The existing bridge was constructed in 1957 and carries Prado Road across San Luis Obispo Creek near the South Higuera Street intersection. Caltrans inspects the bridge every two years as part of its bridge inspection program. In 2001, Caltrans classified the bridge as structurally deficient, indicating that one or more primary structural components had deteriorated to a condition requiring significant rehabilitation or replacement. The bridge was also previously identified as functionally obsolete because of its limited width, lack of modern bicycle and pedestrian facilities, and inability to accommodate current and projected transportation demands. Based on its structural condition and functional limitations, the City and Caltrans concluded that complete bridge replacement represents the most appropriate long-term solution. The new bridge will replace the existing three -span reinforced concrete structure with a single -span precast concrete bridge that eliminates supports within the creek channel, maintaining hydraulic performance, reducing long-term maintenance requirements, and minimizing environmental impacts. The project also includes widening Prado Road and the South Higuera Street intersection, construction of modern bicycle and pedestrian facilities, ADA-compliant sidewalks and crossings, retaining walls, creek bank stabilization, storm drainage improvements, utility relocation, and environmental mitigation. Because the bridge serves as a major utility corridor, the project also includes relocation and protection of critical water, recycled water, sanitary sewer, natural gas, and Page 126 of 1059 Item 6a communications, and electrical infrastructure necessary to maintain utility service throughout construction. Current Milestones for both Proiects and Council Considerations Both the Interchange Project and the Bridge Project have advanced through their respective project delivery processes. As design and technical studies have progressed, the project team has developed additional information and identified several key policy and implementation decisions that are now ready for City Council consideration. For the Interchange Project, Council is being asked to consider establishing an Underground Utility District to facilitate undergrounding of existing overhead utilities within the project corridor, receiving the completed Value Analysis and the draft Bridge Type Selection and Wall Type Selection Reports, authorizing the Assistant City Manager to approve the final Supplemental Project Report upon completion of technical review, approving the recommended interchange aesthetic theme, providing direction regarding gateway branding, and providing direction to evaluate a future Class I shared -use path along Elks Lane through the next Active Transportation Plan update while preserving the opportunity for future implementation through strategic right-of-way acquisition. For the Bridge Project, Council is being asked to consider receiving the Preliminary Value Analysis Study and approving the recommended design refinements that reduce project costs while maintaining the project's operational objectives, multimodal functionality, and long-term performance and authorizing administrative grant adjustments to reconcile funding appropriations, accurately reflect authorized grant reimbursements, and ensure consistency with eligible funding sources. Collectively, these actions represent significant implementation milestones for both projects and will allow design, funding, and project delivery activities to continue while ensuring that major policy decisions remain under the direction of the City Council. New Underground Utility District 17 for the Interchange Project Chapter 13.12, Underground Utilities, of the San Luis Obispo Municipal Code establishes the process for converting existing overhead utility facilities to underground systems. An Underground Utility District is a geographically defined area established by City Council ordinance within which designated overhead electrical, telecommunications, and related facilities must be relocated underground. Establishing a district creates the legal and administrative framework needed to coordinate the conversion among the City, utility providers, and affected property owners. It does not, by itself, approve construction, appropriate funding, or determine every party's final cost responsibility. The City has a long-standing policy of undergrounding overhead utility facilities where practical, particularly when the work can be coordinated with a major roadway, bridge, development, or corridor improvement. Undergrounding removes poles, wires, and guy anchors that can conflict with vehicles, sight distance, sidewalks, and bicycle facilities. It also improves utility -system resilience by reducing exposure to vehicle collisions, wind, fire, and other environmental disruptions; reduces long-term conflicts with roadway, Page 127 of 1059 Item 6a drainage, landscaping, and other public improvements; improves corridor and gateway aesthetics; and creates additional usable space for pedestrians and bicyclists. Coordinating undergrounding with a major capital project can also avoid separate future excavations, traffic closures, construction costs, and periods of public disruption. In 1978, the City and Pacific Gas and Electric Company entered into a franchise agreement granting PG&E the right to construct, operate, and maintain electrical facilities within public rights -of -way. (Attachment C) The agreement requires PG&E to relocate its facilities when they conflict with a City street improvement and recognizes the City's objective of undergrounding overhead facilities where practical. For voluntary undergrounding, cost responsibility is also governed by applicable California Public Utilities Commission rules. Under the anticipated framework, PG&E will calculate the cost of relocating and undergrounding its electrical facilities and provide a credit equal to the estimated cost of reconstructing the affected overhead system. The City will be responsible for the eligible incremental cost of undergrounding beyond that credit. Cost responsibilities for communications facilities and private service conversions will be established through applicable tariffs, franchise requirements, utility agreements, and the final district implementation plan. The City most recently applied this framework to the adjacent Prado Creek Bridge Replacement Project. In 2022, the City Council established Underground Utility District No. 16 for the Prado Road and South Higuera Street bridge and intersection improvements. District No. 16 provided the framework for the City, PG&E, communications providers, and affected property owners to coordinate undergrounding with the Bridge Project. Proposed District No. 17 would continue this coordinated approach along the next segment of the Prado Road corridor within the Interchange Project limits. Together, the two districts would support a more coherent, safer, and more resilient corridor extending through the bridge and interchange project areas. Within the proposed District No. 17 boundaries, PG&E electrical facilities, AT&T and Charter/Spectrum communication lines, and other communications infrastructure are located on overhead poles within or adjacent to the public right-of-way. Several poles conflict with areas that will be reconstructed for the proposed roadway geometry, bridge structures, retaining walls, bicycle and pedestrian facilities, landscaping, and related improvements. Maintaining the overhead system would require substantial pole relocations, constrain the final project design, and retain overhead infrastructure within a corridor undergoing comprehensive reconstruction. The properties affected by District No. 17 generally include parcels within the district boundaries and properties receiving service from the overhead facilities designated for removal. The district map included as Attachment B identifies the geographic limits of the proposed district. During final design, the City and utility providers will confirm the affected facilities, service connections, and properties requiring coordination. Some properties may require modifications to private electrical or communications service equipment before they can receive underground service. The City and utility providers will coordinate directly with those property owners. Page 128 of 1059 Item 6a The properties affected by District No. 17 generally include parcels located within the district boundaries and properties receiving service from the overhead facilities designated for removal. The district map included as Attachment B identifies the geographic limits of the proposed district. Coordination is already underway with affected properties that are currently under development or active construction so that proposed site improvements can be planned to accommodate future underground utility service. If Council establishes District No. 17, the City and utility providers will confirm the service connections needs and commence coordination as the design details are formalized. Chapter 13.12.030 requires formal notice to affected property owners and utility owners before the City Council establishes an underground utility district. For proposed District No. 17, notice was mailed to potentially affected property owners and published in The New Times at least 30 days before the public hearing. The notice described the proposed district and informed affected parties of the opportunity to participate in the Council hearing. Utility providers have also been informed of the City's intent to pursue undergrounding and will continue participating in coordination throughout final design. This district -specific notification supplements the broader public outreach conducted for the Interchange Project, including public workshops, community meetings, advisory -body presentations, environmental review, project website updates, and stakeholder coordination. Following the required notice and public hearing, the City Council may establish the district by ordinance. If adopted, the City and utility providers will complete detailed design, confirm cost responsibilities, coordinate private service conversions, establish an implementation schedule, construct the underground system, transfer customers to underground service, and remove the former overhead facilities. The work will be coordinated with Interchange Project construction whenever practical. After conversion, each utility provider will remain responsible for operating and maintaining its underground facilities in accordance with applicable regulations and agreements. The district boundaries will remain established in the Municipal Code unless subsequently amended or repealed by the City Council. Establishing District No. 17 would allow feasible overhead facilities to be converted underground as part of the Interchange Project instead of through a separate future utility project. This approach would eliminate conflicts between utility infrastructure and transportation improvements, improve safety and sight distance for roadway users, support planned bicycle and pedestrian facilities, increase system reliability and resilience, reduce future maintenance conflicts, and enhance the appearance of the Prado Road corridor and interchange gateway. The draft District No. 17 ordinance, district overview map, and 1978 PG&E franchise agreement are provided as Attachments A, B, and C. Final Value Analysis Report for the Interchange Project As previously mentioned, City Council reviewed the preliminary Interchange Project Value Analysis on November 4, 2025, and approved a preferred set of conceptual, cost -saving Page 129 of 1059 Item 6a design refinements. These refinements established the baseline for the detailed engineering, traffic modeling, and structural design that are now being incorporated into the Interchange Project's Supplemental Project Report. The completed Value Analysis removed $20 million in construction costs from the Interchange's structural costs as compared to the cost shown in the approved Project Report via three major systemic interventions: • Lane Configuration Optimization: Micro -simulation modeling verified that downsizing the overcrossing bridge from four through lanes to two-lane cross- section west of the northbound ramp terminal maintains acceptable traffic operations through 2050. This adjustment avoids operational degradation at adjacent Madonna and Los Osos Valley Road interchanges. A four -lane cross- section is preserved exclusively east of the ramp terminals where localized turning movements peak near South Higuera Street. This modification successfully eliminates millions in structural and roadway costs. Active Transportation Consolidation: The total bridge deck width was reduced by consolidating bike facilities. The refined configuration delivers an expansive, bidirectional Class I shared -use path on the south side of Prado Road paired with a standard sidewalk on the north side. This layout maintains safe, high -quality multimodal connectivity while significantly dropping structural deck mass. Structural Footprint Minimization: The overall elevated structure was shortened by approximately 1,300 linear feet by extending internal bridge spans and integrating strategically placed retaining walls. Crucially, the layout was completely re - engineered to eliminate a structural support pier within the median of US 101. This choice dramatically reduces construction -phase falsework complexity, eliminates high -risk highway lane closures, and completely removes long-term median maintenance liabilities. Figure 2 below provides a rendering of portions of the Interchange Project prior to incorporating the Value Analysis (VA) recommendations, while Figure 3 illustrates the refined design following incorporation of the VA recommendations. The renderings focus on the US 101 overcrossing and the intersection of Prado Road with the northbound US 101 on and off ramps. The primary differences include a narrower overcrossing bridge, replacement of the column -supported roadway structure near the northbound ramp intersection with a Mechanically Stabilized Embankment (MSE) wall and abutment system, and improved aesthetic due to the refined design. Page 130 of 1059 Item 6a The Final Value Analysis Report for the Interchange Project can be found as Attachment D. Bridge Type Selection Recommendation for the Interchange Project The Bridge Type Selection process identifies the optimal architectural configuration for the primary overcrossing deck to match the downsized, performance -based width of 91 feet. The selection process balanced structural efficiency, long-term durability, seismic ductility, and localized site constraints: • Selected Structure Type: The preferred framework utilizes a multi -span Precast Prestressed Concrete Wide Flange Girder structure or a Cast -in -Place Prestressed Concrete Box Girder system. • Span Configurations & Falsework Elimination: In alignment with the Value Analysis findings, structural spans were lengthened to entirely clear the active lanes and median of US 101. Utilizing off -site manufactured precast concrete girders allows components to be craned directly into place, minimizing or entirely eliminating the need for temporary wooden support falsework over highway traffic, thereby preserving public safety and accelerating construction schedules. • Seismic and Foundation Engineering: Substructure foundations will leverage heavy Cast -in -Drilled -Hole (CIDH) concrete pilings driven deep into competent underlying bedrock layers. This configuration provides ideal seismic ductility and prevents differential settlement under California dual -agency (Caltrans/City) design criteria. • Utility Integration Backbone: Because the Prado Road corridor serves as a primary regional utility network backbone, the selected bridge profile incorporates dedicated internal, structural utility cells. This system securely carries wet and dry utility transmission mains across the highway right-of-way, shielding conduits from environmental weathering and eliminating visual clutter. The selected bridge type will support architectural fascia treatments and concrete traffic barriers supporting the chosen aesthetic theme. The draft technical study that supports the bridge type selection recommendation can be found as Attachment E. Wall Type Selection Recommendation for the Interchange Project Because the Value Analysis shortened the elevated concrete bridge spans by 1,300 linear feet, the structural earth embankments leading up to the overcrossing must be supported by an increased volume of retaining walls. Wall selection represents a critical balancing act between construction speed, structural longevity, and spatial right-of-way limitations. The project's finalized structural wall schedule is categorized into distinct applications: • Mechanically Stabilized Embankment (MSE) Walls: Primary choice for the main overcrossing approach ramps and the island wall supporting US 101 Northbound on and off ramps. MSE walls utilize interlocking precast concrete facing panels Page 132 of 1059 Item 6a tied back to layers of high -strength geo-synthetic grid reinforcement straps embedded deep within compacted structural soil backfill. These walls are highly cost-effective, rapid to install, and offer excellent native flexibility to accommodate minor ground settlement without structural cracking. • Cast -In -Place (CIP) Concrete Cantilever Walls: Used selectively at tight right-of- way boundaries, along the realigned Elks Lane corridor, and at specific points where deep underground utility networks intersect. Unlike MSE walls, which require wide horizontal excavations to lay back earth -reinforcement straps, a CIP concrete wall relies on a rigid, steel -reinforced L-shaped structural footing. They are chosen specifically where spatial boundaries are restricted, allowing retention of vertical earth cuts without encroaching on adjacent properties or disrupting critical utility infrastructure. The selected wall variations will support architectural fascia treatments and concrete traffic barriers supporting the chosen aesthetic theme. The draft technical study that supports the wall type selection recommendation can be found as Attachment F. The bridge and retaining -wall type selection process is based primarily on structural performance, constructability, site conditions, long-term maintenance, and cost. Regardless of the bridge and wall types ultimately selected, their visible architectural treatments, colors, textures, materials, and landscaping will be coordinated with the aesthetic theme selected for the Interchange Project. This approach allows the project to use cost-effective and technically appropriate structural systems while maintaining a consistent visual character throughout the corridor. Supplemental Project Report (SPR) for the Interchange Project As a major infrastructure asset transitions from environmental scoping to final design during the Plans, Specifications, and Estimates (PS&E) phase, minor geometric adjustments often deviate from the conceptual limits originally approved by regulatory agencies. For the Prado Road Interchange Project, the extensive cost -saving design modifications developed during the value analysis phase of work diverge from the selected Preferred Alternative Project as documented in the Project Approval and Environmental Documentation (PA&ED) phase. To formalize these technical reconfigurations without invalidating previous project milestones, Caltrans requires preparation of a Supplemental Project Report (SPR), which will document the approved project changes and contain the most current cost estimates and schedule. The SPR benefits the project as it provides: • Formal Codification: It serves as the official engineering record validating significant refinements made to an already approved project configuration. • Timeline Preservation: Unlike an entirely new Project Report, an SPR does not redefine the project's underlying purpose or re-evaluate alternate alignments, Page 133 of 1059 Item 6a completely bypassing the need to restart the multi -year public environmental review cycle from scratch. Engineering Clearance: It provides Caltrans with the comprehensive documentation necessary to demonstrate that the revised, more affordable layout fully satisfies all regional transportation, safety, and multimodal performance metrics. The Interchange Project interfaces directly with the San Luis Obispo Creek channel and its associated active foodway during storm events beginning with the 25-year storm event and continuing through larger flood events. Since the value engineering work introduced significant changes to the bridge structure lengths, supporting center piers, and approach retaining walls, advanced and iterative hydraulic modeling was required during the SPR phase to ensure community protection: Floodway Mitigation: Extensive hydraulic simulations verify that the shortened bridge footprint and MSE wall alignments satisfy the City's Waterway Management Plan and the Federal Emergency Management Agency (FEMA) floodplain requirements. This comprehensive documentation is fully integrated into the SPR discussion and technical appendices to document that regional floodwaters are conveyed appropriately. Scour Safeguards (Structure Technical Policy 2.6): Subsequent to the primary Value Analysis, Caltrans enforced updated, strict hydraulic scour design guidelines under Structure Technical Policy 2.6. Substructure foundation modeling was required to recalculate the exact depth of the Cast -in -Drilled -Hole (CIDH) concrete pilings. This analysis confirms that even if an extreme storm event severely erodes the surface creek bed or surrounding embankments, the underlying bridge foundations remain safely anchored into solid bedrock. • Stormwater Management: Refined stormwater treatment basins, bio-filtration swales, and modified wet utility cross -connections have been engineered into the final design layouts. These systems isolate, treat, and safely discharge roadway runoff prior to its introduction into the local watershed. The draft SPR is currently undergoing comprehensive review by the City's Project Development Team and Caltrans functional units. Staff is requesting that Council delegate authority to the Assistant City Manager to approve the final SPR in order to maintain the project's delivery schedule. Delegating this authority will allow the project to advance immediately upon completion of those reviews and incorporation of the remaining technical appendices, provided no substantive changes are made to the project scope, purpose, or core recommendations. Prior to final approval of the SPR, staff intends to continue discussions with Caltrans regarding identified cost increases and potential opportunities to manage or reduce project costs. The delegated authority would apply only if the final SPR remains substantially consistent with the project scope, purpose, and recommendations presented to Council. Any substantive change to the project scope, purpose, or core recommendations would be returned to Council for consideration. Page 134 of 1059 Item 6a The Draft Supplemental Project Report can be found as Attachment G. Aesthetic Theme for the Interchange Project The project's aesthetic and landscape design must satisfy the mitigation measures established in the Final Initial Study -Mitigated Negative Declaration (IS/MND) and the Visual Impact Assessment (VIA), both of which grant substantial review authority to the Caltrans District Landscape Architect. Under Mitigation Measures and the corresponding VIA guidelines, the City is required to develop a comprehensive landscape plan prior to project approval. This plan must focus on incorporating native, drought -tolerant plant materials that provide a diverse variety of colors, shapes, and species. To soften visual changes and reduce the overall scale of the new structural features, these plantings must be strategically integrated along constructed walls, structures, and benched or graded areas within the project corridor. Once installed, the landscaping is subject to a minimum two-year establishment and oversight period overseen by the District Landscape Architect. To address these mitigation requirements and the project's broader aesthetic objectives, three aesthetic themes have been developed. Reduced -size images of the three themes are shown below, and larger images are provided in Attachment H. Figure 4 — Base Theme Page 135 of 1059 Item 6a Figure 5 — Mission Theme Figure 6 — Modern Mission Theme Page 136 of 1059 Item 6a Each theme comprises multiple design components, including architectural wall treatments, planter walls, railings, fencing, landscaping, and lighting. The themes are not required to function as fixed packages, and individual components may be combined to achieve Council's preferred aesthetic. For example, Council could express an overall preference for the Base Theme while directing that it incorporate the fencing or railing treatment shown in the Mission or Modern Mission Theme. General direction regarding the desired character, level of architectural detail, landscaping, lighting, and preferred individual features will allow the project team to work with Caltrans to refine a cohesive aesthetic design that reflects Council's objectives while satisfying applicable project and agency requirements. The project team reviewed the three themes for consistency with the VIA, applicable Caltrans requirements, the surrounding visual environment, and City policies. Based on the current level of design and coordination, all three themes appear capable of receiving Caltrans approval, subject to further refinement and final review. The project team identified the Base Theme, enhanced with more extensive landscaping and reduced accent lighting, as the option that most directly minimizes the perceived scale of the Interchange Project and supports the objectives of the City's Conservation and Open Space Policy 9.1.1. This policy seeks to preserve natural and agricultural landscapes by ensuring that infrastructure remains visually subordinate to and compatible with its surroundings. However, the Mission and Modern Mission themes provide more distinctive architectural treatments that may more strongly reflect the City's identity and long-term vision for this regional gateway. Council is therefore being asked to consider whether the enhanced Base Theme best addresses the City's aesthetic and policy objectives or whether one of the other themes would more appropriately address the City's needs. The Council -selected theme will be further refined and submitted to Caltrans for final review and approval. As part of this aesthetic refinement, the project team evaluated the integration of large architectural "San Luis Obispo" identification lettering onto the primary retaining wall assemblies. The primary benefit of this treatment is the creation of a highly visible, welcoming landmark that establishes a strong sense of place and identity at one of the City's primary regional gateways. Potential drawbacks include drawing additional attention to the scale and geometry of the interchange, which could conflict with the objective of reducing the visual prominence of the new structures. Accordingly, Council is being asked to provide general direction on both the preferred aesthetic theme (with potential variation of components as described above) and whether to incorporate formal City identification lettering into the final engineering specifications or advance the selected theme with textured architectural fascia treatments and no lettering. If Council directs incorporation of City identification lettering into the Interchange Project, the existing gateway monument adjacent to US 101 near the Prado Road northbound ramps may need to be removed. Caltrans requirements generally limit Page 137 of 1059 Item 6a gateway monuments or community identification features to one visible feature per state highway or interstate approach, in each direction of travel, entering a local jurisdiction. Value Analysis for the Bridge Project On November 4, 2025, the City Council authorized completion of a Value Analysis (VA) for the Bridge Project to determine whether the scale of the proposed improvements remained appropriate in light of the proposed reduction in the scale of the adjacent Interchange Project. A VA is a structured engineering process used to identify opportunities to improve project value by reducing construction and lifecycle costs while maintaining required functionality, safety, durability, and performance. Figure 7 above provides a rendering of the currently planned Prado Road and South Higuera Street intersection improvements, consistent with the design presented to Council on November 4, 2025. Since that time, however, the Preliminary Value Analysis Study (Attachment 1) identified seven potential design refinements intended to reduce project costs and improve constructability, including modifications to bridge geometry, utility relocations, roadway features, and structural elements. On May 20, 2026, the Active Transportation Committee (ATC) reviewed the Value Analysis recommendations within its purview, specifically those affecting bicycle and pedestrian facilities, roadway geometry, and the existing Bob Jones Trail Bridge. The ATC generally supported reducing the bridge width and shortening the raised median, while recommending that the northerly shoulder be replaced with Class II bicycle lanes. The ATC also strongly supported retaining the existing Bob Jones Trail Bridge, or replacing it if relocation becomes necessary, unless the cost of replacement becomes prohibitive. Page 138 of 1059 Item 6a If Council directs implementation of Value Analysis recommendations that modify the currently planned improvements, the project design and associated renderings will be updated to reflect those changes as the project advances through final design. The Preliminary Value Analysis evaluated the following recommendations: Table 1 —Value Analysis Alternatives Alternative Description Estimated Savings Staff Recommendation Reduce the bridge Approve. The revised bridge width from 114 feet to width accommodates 91 feet by eliminating forecast traffic associated one eastbound lane, with the Prado Interchange 1.0 — Reduce narrowing lane 000000 $3,, Project while substantially Bridge Width widths, reducing reducing construction median width, and costs. Staff recommends simplifying bicycle incorporating Class II and pedestrian bicycle lanes consistent facilities. with ATC direction. Do Not Approve. Retain relocated Undergrounding is 2.0 — Eliminate electrical and consistent with City policy Utility communication facilities $500,000 and improves long-term Undergrounding overhead rather than corridor aesthetics and undergrounding them. reliability. Delegate to the City Engineer. Final utility cover 3.0 — Reduce Reduce minimum utility requirements should be Utility Trench cover requirements $100,000 determined during final Depth where technically design based on feasible. engineering, utility owner, and maintenance considerations. Conditional Approval. Relocate only utilities Complete only those utility crossing the bridge and improvements that are 4.0 — Limit Wet defer replacement of $300,000 supported by available Utility Relocations adjacent water utility funding and provide infrastructure to a future project. long-term operational benefit. Page 139 of 1059 Item 6a Alternative Description Estimated Savings Staff Recommendation Replace soldier pile Approve, subject to final retaining walls engineering. Staff 5.0 — Replace beneath the bridge recommends advancing Soldier Pile Walls with Rock Slope $2,000,000 this alternative provided with Rock Slope Protection (RSP), hydraulic and scour Protection subject to hydraulic analyses confirm the verification. design meets applicable standards. Reduce the length of Approve. This modification 6.0 — Shorten the raised median while $20,000 maintains operational Raised Median maintaining required objectives while providing a access restrictions. modest cost reduction. Permanently remove Do Not Approve. The ATC 7.0 — Remove the existing pedestrian recommendation to retain or Existing Bob bridge rather than $150,000 replace the bridge unless Jones Trail Bridge relocating or future replacement costs reconstructing it. become prohibitive. Total VA Identified Savings $6,070,000 Alternatives 1.0 — 7.0 Total VA Recommended Savings $5,420,000 Alternatives 1.0, 3.0, 4.0, 5.0, and 6.0 Based on the completed Value Analysis and subsequent engineering review, Council is being asked to approve incorporation of Alternatives 1.0, 5.0, and 6.0 into the final project design to achieve approximately $5 million in construction savings while maintaining the project's operational objectives, multimodal connectivity, and long-term functionality. Council is also being asked to authorize the City Engineer to determine the appropriate implementation of Alternatives 3.0 and 4.0 during final design based on engineering requirements, available utility funding, and coordination with utility owners. Alternatives 2.0 and 7.0 are not proposed for implementation because they are inconsistent with City policy, community objectives, or Active Transportation Committee recommendations. Schedule Impacts Related to Value Analysis Recommendations The construction durations identified in the Value Analysis reflect only the estimated time required to construct the project elements that would be added, modified, or removed. They do not include the additional time required for design, environmental review, permitting, or agency coordination. In particular, implementation of Alternative 1.0, Bridge Width Reduction, and Alternative 5.0, Rock Slope Protection, will require additional traffic, Page 140 of 1059 Item 6a hydraulic, geotechnical, and environmental analyses; revisions to the project plans; and environmental revalidation to confirm that the modified design remains consistent with the previously approved environmental documentation. Although the resulting design effort and schedule impacts have not yet been fully quantified, the anticipated reductions in construction complexity, duration, and cost are expected to outweigh the additional work required during final design. Following Council direction, the additional analyses and approved recommendations will be documented in the Final Value Analysis Study Report and incorporated into the project plans, specifications, and cost estimates. The project schedule will be updated as the scope and duration of the remaining work become better defined. The Value Analysis also identified potential benefits from coordinating construction of the Prado Creek Bridge and Prado Road Interchange Projects. Coordinated delivery could reduce cumulative impacts to the traveling public, improve contractor mobilization and construction sequencing, avoid duplicative traffic control and public outreach, and potentially reduce overall construction costs. Opportunities to coordinate the projects will continue to be evaluated during final design based on grant requirements, environmental permits, regulatory approvals, utility coordination, and other project -delivery commitments. The objective is to capture practical coordination benefits without unnecessarily delaying either project. Flkc I ana The Active Transportation Committee (ATC) recommended pursuing a Class I shared - use path along Elks Lane and evaluating the long-term corridor alignment through a future update to the Active Transportation Plan (ATP). Incorporating this improvement into the current Prado Road Interchange Project or Prado Creek Bridge Project is not proposed because construction of a Class I facility along Elks Lane is outside the approved scope and currently identified funding for both projects. However, the Prado Road Interchange Project provides an opportunity to preserve the ability to construct a Class I facility along Elks Lane in the future. Both the existing and proposed portions of Elks Lane are not currently wide enough to accommodate a Class I facility within the planned right-of-way. If directed by the City Council, staff could evaluate and acquire the additional right-of-way necessary to accommodate a future shared -use path as part of the Prado Road Interchange Project. Securing the necessary right-of-way in conjunction with the Interchange Project could reduce the need for future property acquisition and preserve flexibility for implementation once the corridor planning and design are further developed. At this time, a conceptual alignment and roadway configuration incorporating a Class I facility along Elks Lane have not been developed. As a result, the required right-of-way, roadway geometrics, potential project impacts, and implementation costs are not yet known. If the City Council supports advancing the concept, staff would further develop the Class I facility in coordination with the ATC as part of a future ATP update. That process would evaluate the preferred alignment and configuration, identify planning -level Page 141 of 1059 Item 6a costs, and establish the facility's relative priority within the City's broader active transportation network. Following completion of that planning process, the City Council could consider whether and when to advance construction of the Class I facility through a future Capital Improvement Program planning and budgeting process. Accordingly, the current Council action would focus on preserving the opportunity for a future Class I facility rather than committing the City to its construction or a specific facility configuration. Previous Council or Advisory Body Action Interchange Project In 1978 a Franchise Agreement between the City and PG&E was executed which outlines parameters under which PG&E may use the City's rights -of -way for PG&E facilities. The Interchange Project is included in the City's 1992 Circulation Element of the City's General Plan. Previous City Councils have established 16 other underground utility districts. Establishing a district defines the geographic area within which designated overhead utility facilities must be relocated underground and provides the legal and administrative framework for coordinating the conversion among the City, utility providers, and affected property owners. These districts are often established in conjunction with new development or the reconstruction of major transportation corridors. The most recent constructed City -funded capital project that included utility undergrounding was the 2005 widening of Broad Street/State Route 227, associated with Ordinance 1442. On July 17, 2018, City Council approved the Supplemental Environmental Impact Report (SEIR) for the San Luis Ranch Development (Staff Report). The SEIR detailed the impacts of the development and need for the Interchange Project, but did not cover the project itself, necessitating separate CEQA and NEPA documents. The Interchange Project implements portions of the City's Tier 1 bicycle and pedestrian network. The Active Transportation Plan was adopted by Council on February 2, 2021. On August 16, 2022, Council Authorized Staff to seek VA services and PS&E services (Staff Report). On September 5, 2023, Council recommended approval of the IS/MND to Caltrans, declared Alt 3 as the City's preferred interchange type, and recommended that Caltrans Administration approve the Project Report. (Staff Report) On February 18, 2025, Council awarded the PS&E design contract to Consor Engineering (Staff Report). Page 142 of 1059 Item 6a On October 23, 2025, the Active Transportation Committee reviewed the Interchange Project's VA alternatives and made recommendations to Council. (Staff Report) On November 4, 2025, the City Council directed staff to implement Value Analysis recommendations that reduced anticipated construction costs by $20 million. (Staff Rom) Bridge Project On August 20, 2013, the City Council approved a Request for Proposals for consultant services for the Prado Road Bridge Widening Project, authorized the City Manager to execute an agreement with the selected consultant, and authorized the Finance Director to execute and amend purchase orders within the Council -authorized project budget. (Staff Report) On October 21, 2014, the City Council approved the preferred conceptual alternative to replace the existing Prado Road bridge with a new single -span bridge, appropriated $390,000 in Transportation Impact Fee funds for continued project study and engineering, and authorized staff to pursue Highway Bridge Program funding. (Staff Report) The Bridge Project implements portions of the City's Tier 1 bicycle and pedestrian network. The Active Transportation Plan was adopted by Council on February 2, 2021. On October 4, 2022, the City Council introduced an ordinance to establish Underground Utility District 16 within the Prado Bridge Replacement Project limits and adopted Resolution No. 11368 approving the Final Initial Study/Mitigated Negative Declaration for the Project. (Staff Report) On October 18, 2022, the City Council adopted Ordinance No. 1721, establishing Underground Utility District 16 within the Prado Bridge Replacement Project limits. (Staff Rom) On November 4, 2025, the City Council directed staff to complete a Value Analysis for the Project and return to the Council with the results. (Staff Report) On May 20, 2026, the Active Transportation Committee reviewed Prado Road Interchange and Prado Creek Bridge project's proposed bicycle and pedestrian improvements and provided the following recommendations for Council's consideration via a 4-0 vote. (Staff Report): • The committee concurs with staff's presentation in terms of the value analysis of the bridge adding that staff explore the possibility of a Class II bike lane on the North part of Segment 3. • The committee requests that the existing Bob Jones bridge remain in its current configuration by reducing the width of the Prado bridge. • The committee recommends the establishment of a Class I, shared -use path, on the new segment of Elks Lane to be developed in the near term. Page 143 of 1059 Item 6a Public Engagement The Prado Interchange Project has included extensive public outreach throughout project development including: • Public workshops. • Community meetings. • Advisory body presentations. • Project website updates. • Environmental review circulation. • Stakeholder coordination meetings. The most current Public Workshop occurred on March 11, 2026, at the Pavillion in San Luis Ranch. Additionally, as required by the Municipal Code 13.12.30, a mailer notice was sent to all potentially affected properties and published in The New Times 30 days prior to this first hearing for the creation of the Underground Utility District. CONCURRENCE This project has concurrence from the Community Development, Public Works, and Utilities Departments. Utility providers have been informed of the City's intent to pursue undergrounding within the project corridor and will continue participating in utility coordination efforts during PS&E. ENVIRONMENTAL REVIEW Both the Interchange and Bridge Projects are advancing in compliance with the California Environmental Quality Act (CEQA) and the National Environmental Policy Act (NEPA). For the Interchange Project, Caltrans serves as the lead agency for both CEQA and NEPA. For the Bridge Project, the City of San Luis Obispo serves as the CEQA lead agency, and Caltrans serves as the NEPA lead agency. Accordingly, City Council adoption of the environmental document by resolution is not required for environmental documents for which Caltrans is the lead agency. Interchange Project The Interchange Project has the following environmental clearances: • CEQA Compliance: Approved via an IS/MND. • NEPA Compliance: Documented via a Categorical Exclusion (CE), with Caltrans acting as the federal lead agency. Page 144 of 1059 Item 6a Because the VA implementation results in final design changes, the City will submit a Supplemental Project Report to Caltrans to initiate environmental revalidation. Caltrans will evaluate whether the existing CEQA IS/MND and NEPA Categorical Exclusion remain valid in light of the revised project scope, design, and any new environmental information or regulatory requirements. The revalidation process will document whether the existing environmental approvals remain valid, require supplemental documentation or public review, or must be replaced with new environmental documentation. Based on Caltrans' initial feedback, the existing environmental approvals appear likely to remain valid, although supplemental documentation may be required to support that determination. Bridge Project The Bridge Project has the following environmental clearances: • CEQA Compliance: Approved via an IS/MND by the City Council on October 4, 2022, by Resolution Number 11368 (2022). • NEPA Compliance: Documented via a Categorical Exclusion (CE), with Caltrans acting as the federal lead agency. FISCAL IMPACT Budgeted: Yes Budget Year: 2025-30 Funding Identified: Yes Table 2 — Standard Financial Table Funding Total Budget Budget Remaining Annual Ongoing Sources Available Adjustment Balance Cost Federal: $ 4,130,000 $-2,065,000 $ 2,065,000 $ 0 Earmark Federal: HBP $ 6,000,000 $-6,000,000 $ 0 $ 0 Total $ 10,130,000 $-8,065,000 $ 2,065,000 $ 0 Table 2 summarizes the recommended grant -fund budget revisions. Additional information regarding these adjustments is provided in the "Grant Fund Administrative Adjustments" section below. Fiscal Analysis: Both the Interchange Project and the Bridge Project are included in the City's 2025-27 Financial Plan. The Interchange Project appears on page 384 of the plan. The Bridge Project appears on page 379 of the plan. Below is a summary of the anticipated costs and current funding plans for both projects. The funding plans should not be viewed as final, as the City is actively working with its consultant teams to identify and pursue additional funding opportunities. These efforts Page 145 of 1059 Item 6a include pursuing competitive grant programs, coordinating with regional and state funding partners, positioning both projects for future funding opportunities, evaluating financing strategies, and identifying other opportunities to reduce the amount of funding ultimately required from existing City resources. Simply put, the goal is to provide Council with the best available information about what these projects are expected to cost at the time of each update while maximizing regional, state, federal, and grant funding to keep the impact on existing City resources as low as possible. Interchange Project: Grant and Financing Strategy The City is actively pursuing a diversified funding strategy for the Prado Interchange Project rather than relying solely on existing local revenues or waiting for a future funding opportunity. The Consor project team, is providing grant strategy and application support during the Plan Specification & Estimate phase. This work includes identifying and evaluating federal, state, and regional discretionary funding programs, assessing the project's competitiveness, developing strategies to better position the project for future funding cycles, and preparing grant applications for promising opportunities. The City is also coordinating directly with SLOCOG, Caltrans, the California Transportation Commission, and other regional and state partners to identify potential funding opportunities and strengthen the project's competitiveness. The City's strategy includes pursuing major state and federal transportation programs as they become available and developing the technical, economic, and project -readiness information necessary to compete successfully. The City is also pursuing opportunities for legislative and other discretionary funding and is continuing advocacy efforts intended to elevate the project at the regional, state, and federal levels. The project financing strategy is therefore expected to consist of a combination of existing transportation impact fee revenues, regional transportation funding, state and federal grants, other discretionary funding, and potentially debt financing. If approved by voters in November 2026, the SLOCOG's proposed tax measure may provide another potential funding source that could assist with the Interchange Project, subject to the measure's final requirements, Council priorities, and future budget decisions. In addition, the City is working with Kosmont, a financial consultant, that is providing expertise on debt and loan strategies for financing construction costs. Based upon the Value Analysis (VA) and Supplemental Project Report (SPR), the estimated construction cost for the Interchange Project is $80 million in 2026 dollars. Table 3 below escalates those dollars based upon a range probable inflationary factors until the anticipated start of construction in 2029. Page 146 of 1059 Item 6a Table 3 — Construction Escalation Construction Cost Escalation Base Year (2026) $80,000,000 3% Inflation (2029) $87,400,000 5% Inflation (2029) $92,600,000 8% Inflation (2029) $100,800,000 The VA process identified opportunities to reduce project costs through refinements to the roadway configuration, consolidation of active transportation facilities, and reductions in the overall structural footprint. However, as the design has advanced, these savings have been partially offset by additional costs associated with utility relocations, updated bridge scour requirements, bridge revisions needed to accommodate sight -distance and truck -turning requirements, and enhanced aesthetic treatments. The largest anticipated cost increase is associated with utility relocations. Current estimates include approximately $9 million for the relocation of electrical, communications, natural gas, water, sewer, and petroleum facilities, including facilities owned by Phillips 66. These estimates are based on increasingly developed utility designs, although the Phillips 66 relocation remains at a more conceptual level and will require further refinement. Additional structural costs have also resulted from updated Caltrans requirements and further development of the project geometry. In December 2025, Caltrans issued Structure Technical Policy (STP) 2.6, which requires applicable structures within waterways and flood -prone areas to be designed for scour associated with a 200-year flood event. The project team requested a variance based on the project's location within a floodplain rather than directly spanning a creek; however, Caltrans denied the request, making compliance with the updated standard mandatory. The estimated cost to address this need is approximately $2.5 million. In addition, the western approach to the Prado Road overcrossing must widen from approximately 65 feet to nearly 90 feet to provide adequate sight distance and accommodate the turning movements of large legal design vehicles at the northbound ramp terminal intersection without encroachment into opposing traffic. The resulting geometric flare creates an irregular bridge configuration for which a cast -in -place, post - tensioned concrete box -girder structure is preferred because of its greater geometric flexibility compared with precast alternatives. The widened bridge geometry has increased the estimated project cost by approximately $2.5 million. The current estimate also includes approximately $4 million for enhanced aesthetic treatments to project structures. This allowance is intended to support architectural treatments and other visual enhancements that will be further defined through coordination among the City, Caltrans, and the project design team. Landscaping costs are not yet included in the estimate and will be developed once the scope is sufficiently defined and confirmed with Caltrans. Page 147 of 1059 Item 6a Staff intends to further discuss Caltrans additions with Caltrans to confirm their scope, necessity, funding eligibility, and associated cost. The updated expenditure plan in Table 5 reflects the current understanding of project scope and anticipated construction costs, including a five -percent annual inflationary factor, and will continue to be refined as the project advances through final design. Table 4 provides the current planning -level cost comparison. Table 4 — Cost Comparison (Interchanae Proiect) Category Current Cost Descriptions Value Analysis cost reductions previously Previously reported anticipated reduction; directed by Council ($20.0 million) detailed reconciliation is included in the VA (November 2025) memorandum. Electrical, communications, natural gas, Utility relocation scope $9.0 million water, sewer, petroleum, and Phillips 66 facilities; scope remains under refinement. Caltrans scour and geometric $5.0 million Current estimate for updated requirements requirements and bridge -geometry development. Enhanced aesthetic . $40 million Current allowance; landscaping is not yet treatments included. Table 5 below presents the Interchange Project Expenditure Plan, which incorporates a five -percent annual inflationary factor to account for anticipated escalation through construction. Table 5 — Interchanae Proiect's Expenditure Plan. Specification No. 2091613 Phase Current 2027-28 2028-29 2029-30 Design $10,045,780 $1,500,000 Phase 1 $3,049,853 Phase 2 $5,901,488 Phase 3 $94,439 Amendment 1 $22,018 Amendment 2 - Amendment 3 - Contingencies $977,982 Third Party Review $1,500,000 Right of Way $2,000,000 Utilities Relocation $2,000,000 $7,000,000 Construction Admin $2,000,000 Construction Management $10,000,000 Page 148 of 1059 Item 6a Construction $112,600,000 Construction $92,600,000 Contract Contingency $20,000,000 Construction $131,600,000 Phase Total Total Per Year $10,045,780 $3,500,000 $2,000,000 $131,600,000 Grand Total for $147,145,780 Project' Table 6 — Interchanae Proiect's Fundina Plan Funding Source Current 2027-28 2028-29 2029-30 Local Funds: $15,261 $85,212,196 Capital Outlay (LRM) $15,261 Debt Finance $85,212,196 Regional Funds: $1,435,260 Regional Grant (County) $1,435,260 Developer Funds: $10,483,063 $2,000,000 $2,000,000 $11,000,000 Capital Outlay (SLR) $9,967,681 $2,000,000 $2,000,000 $11,000,000 AASP TIF $79,205 Citywide TIF $436,177 Grants: $35,000,000 Grant (SLOCOG) $10,000,000 Grant (Future) $25,000,000 Construction Phase Total $131,212,196 Total Per Year $10,498,324 $3,435,260 $2,000,000 $131,212,196 Grand Total for Project $147,145,780 During prior Council discussions, $75 million was identified as the upper planning -level assumption for potential debt financing. The updated funding plan shown in Table 6 increases this assumption by approximately $10.2 million, to $85.2 million. This adjustment is necessary to balance the current expenditure plan, which now incorporates anticipated construction -cost escalation through 2029, refined utility -relocation costs, additional structural and geometric requirements identified through Caltrans review, aesthetic improvements, construction management, and contingency. The increased amount represents a planning assumption based on currently available information and does not constitute authorization to issue debt. Staff will continue to pursue grant funding, regional contributions, project savings, and other outside funding sources to reduce the amount ultimately financed. Staff will also continue working with Caltrans to evaluate the scope, necessity, funding eligibility, and 1 Summation of Total Per Year row above the Grand Total for Project Row Page 149 of 1059 Item 6a cost of the additional Caltrans requirements. Any outside funding secured above the assumptions included in Table 6 or project costs avoided would reduce the debt -financing requirement. Bridge Project: Grant and Financing Strategy The City is similarly pursuing additional outside funding for the Bridge Project. Since the project includes substantial transportation safety, multimodal, bridge replacement, and infrastructure -resiliency benefits, staff is evaluating funding programs that may be applicable to specific components of the project rather than relying exclusively on a single grant program. A current focus is the Highway Safety Improvement Program (HSIP) Cycle 13. The Bridge Project has been identified as the stronger of the two Prado projects for potential HSIP funding because of the documented collision history near the Prado Road and South Higuera Street intersection and the safety improvements incorporated into the project. The City is working with the project team to evaluate and prepare an application, with particular attention to structuring the funding request around eligible safety improvements in a manner that maximizes the project's benefit -cost ratio. The City is also coordinating with SLOCOG to better understand lessons learned from previous HSIP funding efforts and identify opportunities to strengthen the application. Implementation of the recommended VA alternatives is estimated to reduce construction costs by approximately $5 million, resulting in an estimated construction cost of approximately $23 million in 2026 dollars. If Council supports coordinating the construction schedules of the Bridge and Interchange Projects, construction of the Bridge Project would begin in summer 2029 instead of summer 2027, representing an approximately two-year delay from the construction schedule currently identified. Coordinating the projects could provide construction efficiencies by reducing duplicated mobilization, traffic control, construction management, utility coordination, and other costs associated with delivering the projects separately. Coordination could also reduce the duration and cumulative effects of construction on nearby residents, businesses, and roadway users. After accounting for the estimated effects of construction -cost inflation associated with the delayed construction schedule, the recommended VA alternatives are still anticipated to provide a net construction -cost reduction. Using a 5% annual escalation factor, the estimated $23 million construction cost in 2026 dollars would increase to approximately $26.6 million in 2029. This remains approximately $1.4 million below the estimated $28 million construction cost before implementation of the recommended VA alternatives. This comparison reflects the estimated VA savings after escalation but does not include any additional savings that may result from coordinating construction of the Bridge and Interchange Projects. Table 7 shows the estimated construction cost of the Bridge Project in 2029 under a range of potential annual construction -cost escalation rates. Staff will further evaluate potential Page 150 of 1059 Item 6a coordination savings as the construction schedules, project -delivery approach, and bid - packaging strategy are refined if Council directs staff to coordinate construction of the two projects. Table 7 — Construction Escalation (Bridae Proiect) Construction Cost Escalation Base Year (2026) $23,000,000 3% Inflation (2029) $25,100,000 5% Inflation (2029) $26,600,000 8% Inflation (2029) $29,000,000 The Bridge Project expenditure plan shown in Table 8 has been updated to reflect implementation of the recommended VA alternatives. The updated expenditure plan includes additional design service costs necessary to complete the engineering, environmental revalidation, permitting coordination, and plan revisions associated with the recommended project modifications. Construction costs have also been escalated to reflect a potential 2029 construction start, consistent with the possibility of coordinating construction of the Bridge Project with the Interchange Project. Based on currently identified funding sources and the updated expenditure plan, the Bridge Project is anticipated to have approximately $5.1 million in excess funding, which could potentially be reallocated to support the Interchange Project and reduce future debt - financing needs. Any such reallocation would require future City Council authorization and would be evaluated after confirming the Bridge Project's final grant requirements, cost estimate, contingency needs, and construction schedule. Table 8 — Bridge Proiect's Expenditure Plan Phase Balance 2026-27 2027-28 Design $500,000 Right of Way $1,000,000 Utilities Relocation $777,546 Construction Admin $400,000 Construction Management $3,000,000 Construction $26,600,000 Construction Contingency $4,000,000 Total Per Year $1,500,000 $34,777,546 Grand Total for Project2 $36,277,546 Table 9 — Bridge Proiect's Fundinq Plan Funding Source Balance 2026-27 2027-28 Local Funds: $6,502,885 $3,500,000 $14,158,406 Capital Outlay (IIF) $4,749,972 $3,500,000 $11,158,406 Capital Outlay (LRM) $1,667,019 $ 3,000,000 Capital Outlay $85,894 Developer Funds: $1,230,906 $0.00 $0.00 2 Summation of Total Per Year row above the Grant Total for Project Row Page 151 of 1059 Item 6a AASP TIF $135,490 Citywide TIF $1,095,497 Grant Funds: $2,065,000 $0.00 $13,920,349 Earmark $2,065,0003 $58,676.00 Highway Bridge Program $ 4 $13,861,673 Total Per Year $9,798,791 $3,500,000 $28,078,755 Grand Total for Project $41,377,546 Grant Fund Administrative Adjustments The Bridge Project is currently funded by two separate grants. The first source of grant funds is the Highway Bridge Program and the second source is Federal Earmark Funds. The following grant appropriation revisions are included in Staff's recommendations and documented in Attachment J: • Decrease the Federal Earmark Fund appropriation from $4.130 million to the correct amount of $2.065 million. The City appropriated the $2.065 million maximum grant reimbursement amount through the 2023-25 Financial Plan and inadvertently appropriated the same amount again through the 2025-27 Financial Plan. Because the grant funding only needed to be appropriated once, the recommended adjustment eliminates the duplicate appropriation and accurately reflects the available grant amount. • Decrease the current Highway Bridge Program appropriation from $6 million to $0. The Highway Bridge Program is a reimbursement grant administered by Caltrans. Before incurring eligible project costs, the City must complete the required authorization process and receive Caltrans approval to proceed with the applicable phase of work. Costs incurred before authorization, or costs that do not comply with grant requirements, are not eligible for reimbursement. This adjustment does not reduce the approximately $13.861 million in Highway Bridge Program funding currently anticipated for the Bridge Project. Instead, it removes funds that are not yet authorized for expenditure and aligns the appropriation with the anticipated timing of the work. Staff will appropriate the authorized grant amount through a future budget action after Caltrans authorizes the funds for expenditure. These appropriation revisions are administrative budget corrections and do not change the Bridge Project's overall funding strategy, reduce the grant funding anticipated for the project, or require an additional General Fund contribution. The revisions accurately reflect the Federal Earmark Fund award amount and the timing of Highway Bridge Program funding authorization. Staff will return to the City Council to appropriate the authorized Highway Bridge Program funds when they become available for expenditure. 3 Earmark Grant Fund balance reflects recommended decrease in appropriated balance of $2.065 million. 4 Highway Bridge Program Grant Fund balance reflects recommended decrease in appropriated balance of $6 million. Page 152 of 1059 Item 6a The City's Financial Management Manual requires Council approval before staff submits grant applications exceeding $5,000. Securing grant funding is a primary strategy for reducing the City's direct cost of delivering the Interchange and Bridge Projects. Attachment K is a resolution that would authorize staff to pursue and submit eligible grant applications for either or both projects. These are significant transportation investments that will improve safety, mobility, system reliability, and long-term community development along the Prado Road corridor. Because grant opportunities may arise on compressed schedules, advance Council authorization will allow staff to respond promptly while maintaining consistency with the approved project scope, City plans and policies, and applicable grant requirements. • The resolution does not appropriate funding, accept a grant award, authorize expenditures, or commit the City to a local match. If either project receives grant funding, staff will return to the City Council with the award details, proposed budget amendment, required local match, and any requested authority to execute grant documents. REQUESTED COUNCIL DIRECTION The recommendations presented in this report are intended to establish the policy and implementation direction necessary to continue advancing the Prado Road Interchange Project and Prado Creek Bridge Replacement Project through final design. Council is requested to provide direction and take action on the following items: 1. Underground Utility District No. 17. Introduce the ordinance establishing Underground Utility District No. 17 within the Prado Road Interchange Project limits to provide the legal and administrative framework for converting designated overhead utility facilities to underground service. 2. Interchange Project Technical Studies. Receive the completed Interchange Project Value Analysis and the draft Bridge Type Selection and Wall Type Selection Reports. 3. Supplemental Project Report. Authorize the Assistant City Manager to approve the final Supplemental Project Report following completion of City and Caltrans technical and environmental review, provided the final document remains substantially consistent with the project scope, purpose, and recommendations presented to Council. Any substantive change would be returned to Council for consideration. 4. Interchange aesthetic theme and gateway identification. Select the preferred aesthetic theme for the Interchange Project (with variations as Council deems appropriate) and provide direction on whether the final design should incorporate formal "San Luis Obispo" identification lettering. All three themes appear capable of receiving Caltrans approval, subject to further refinement and final review. If identification lettering is selected, the existing gateway monument near the Prado Road northbound ramps may need to be removed to comply with Caltrans requirements limiting visible gateway or community identification features along each highway approach. Page 153 of 1059 Item 6a 5. Future Elks Lane Class I shared -use path. Provided irection on whether to evaluate and acquire the additional right-of-way necessary to preserve the opportunity for a future Class I shared -use path along Elks Lane. Planning, design, prioritization, funding, and construction of the facility would be addressed through a future Active Transportation Plan update and Capital Improvement Program process. 6. Bridge Project Value Analysis. Receive the Preliminary Value Analysis Study and approve incorporation of Alternatives 1.0, 5.0, and 6.0 into the final Bridge Project design. Authorize the City Engineer to determine the appropriate implementation of Alternatives 3.0 and 4.0 during final design based on engineering requirements, available utility funding, and coordination with utility owners. Alternatives 2.0 and 7.0 are not recommended for implementation. 7. Coordinated construction schedule. Provide direction on whether to continue evaluating a coordinated construction schedule that would shift the anticipated Bridge Project construction start from summer 2027 to summer 2029 to better align with the Interchange Project. Further evaluation would consider potential construction efficiencies, inflation, grant requirements, permitting, utility coordination, project -delivery risks, and impacts to the traveling public. 8. Bridge Project grant appropriations. Approve the recommended administrative budget revisions to eliminate the duplicate Federal Earmark Fund appropriation and remove the Highway Bridge Program appropriation until Caltrans authorizes the funding for expenditure. These adjustments do not reduce the anticipated grant funding, alter the overall project funding strategy, or require an additional General Fund contribution. 9. Grant application authority for both projects. Adopt the resolution authorizing submission of eligible grant applications for the Interchange and Bridge Projects. The resolution would authorize grant applications but would not appropriate funds, accept an award, commit the City to a local match, or authorize project expenditures. Any grant award and associated funding commitment would be returned to Council for consideration. ALTERNATIVES Decline to Establish Underground Utility District No. 17 for the Interchange Project and NOT underground the utilities. The City Council could choose not to introduce the ordinance establishing Underground Utility District No. 17 and instead direct that relocated utility facilities remain overhead. This approach would result in additional utility poles throughout the interchange corridor, increase conflicts with sidewalks, bicycle facilities, landscaping, and retaining walls, reduce the long-term reliability of electrical and communication infrastructure, diminish the visual quality of one of the City's primary gateways, and require redesign of portions of the project to accommodate overhead facilities. 2. Decline to Establish Underground Utility District No. 17 for the Interchange Project and underground the utilities. The City could elect not to establish Page 154 of 1059 Item 6a Underground Utility District No. 17 and could still pursue undergrounding within the Interchange Project area through individual agreements with utility providers and affected property owners. This approach, however, would rely on voluntary cooperation and separate negotiations rather than the uniform legal and administrative process established by Chapter 13.12. Without a district, the City may have limited ability to require timely conversion of private service connections, establish consistent deadlines, coordinate all affected utilities and properties, or require removal of remaining overhead facilities. Separate agreements could also increase administrative effort, create schedule uncertainty, result in inconsistent treatment among affected properties, and increase the risk that some overhead facilities remain after project construction. Establishing the district provides a clearer and more coordinated process for completing the underground conversion in conjunction with the Interchange Project. 3. Decline the Recommended Value Analysis Modifications for the Bridge Project. The City Council could direct that the Bridge Project continue through final design without implementing some or all of the recommended Value Analysis (VA) refinements. This approach would increase anticipated construction costs by approximately $5 million while providing limited operational benefit. Higher project costs would increase the City's local funding obligation. 4. Select Different Aesthetic Treatments for the Interchange Project. The City Council may select a different aesthetic theme or provide alternative direction regarding gateway branding, landscaping, architectural treatments, or lighting. Staff can incorporate Council direction during PS&E development however, selecting an alternative aesthetic treatment may require additional aesthetic review by Caltrans. 5. Decline Authorization for Administrative Approval of the Supplemental Project Report. The City Council could require the Supplemental Project Report (SPR) to return for final Council approval following completion of all Caltrans reviews. The SPR is primarily a technical engineering document that formalizes design refinements and technical analyses previously considered by the City Council. Requiring an additional Council hearing following completion of the Caltrans review process could extend the project delivery schedule prior to approval of the final document. If substantive changes to the project scope, purpose, or recommendations occur during Caltrans review, the item could be returned to the City Council for further consideration. 6. Decline the Recommended Budget Adjustments. The City Council could decline the proposed grant appropriation adjustments. The proposed actions are administrative in nature and are intended to align the grant appropriations with reimbursement authorizations. Declining these adjustments could complicate project accounting, reimbursement requests, and future financial reporting but would not affect the overall project budgets or funding levels. Page 155 of 1059 Item 6a ATTACHMENTS Interchange Project A - Draft Ordinance to establish a new Underground Utility District 17 B - Proposed Underground District Overview Map C -PG&E Franchise Agreement (1978) D -Final Value Analysis Memorandum E - Draft Bridge Type Selection Report F - Draft Wall Type Selection Report G -Draft Supplemental Project Report H -Aesthetic Treatments Bridge Project I - Preliminary Value Analysis J - Draft Resolution for Submittal of Budget Adjustment for Prado Creek Bridge Project Interchange and Bridge Project K - Draft Resolution Authorizing Submittal of Grant Applications for Prado Interchange and Prado Creek Bridge Projects Page 156 of 1059 ORDINANCE NO. (2026 SERIES) AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF SAN LUIS OBISPO, CALIFORNIA, AMENDING SECTION 13.12.040 OF THE SAN LUIS OBISPO MUNICIPAL CODE TO ESTABLISH A NEW UNDERGROUND UTILITY DISTRICT 17 WHEREAS, The City of San Luis Obispo wishes to improve the resiliency and appearance of the City by the removal of overhead utilities; and WHEREAS, the limits of the Prado Interchange Project, Specification 2091613 (Project) will require significant overhead utility work during construction; and, WHEREAS, the City and overhead utility purveyors will be able to share undergrounding costs; and, NOW, THEREFORE, BE IT ORDAINED by the Council of the City of San Luis Obispo as follows: SECTION 1. The following Subsection 17 of Section 13.12.040 of the San Luis Obispo Municipal Code is hereby added to establish Underground District 17: 17. That portion of Prado Road in the City of San Luis Obispo, County of San Luis Obispo, State of California, described as follows: COMMENCING at a point on the centerline of Higuera Street that bears South 27' 41' 25" West, 161.18 feet from a found brass pin in monument well marking the intersection of the centerline of Higuera Street with the centerline of the Higuera Street Cul-de-sac as shown on the Record of Survey filed in Book 114 of Records of Surveys at page 89 and on the map of Higuera Commerce Park Tract No. 703 filed in Book 10 of Maps at page 50, in the Office of the County Recorder of said County, from which said brass pin, a found pin in monument well marking the intersection of the centerline of Higuera Street with the centerline of Tank Farm Road as shown on said maps, bears South 27' 41' 25" West, 798.90 feet [South 26' 09' 20" West 798.84 feet per said record of survey]; Thence North 62' 18' 35" West, 42.00 feet to the northwesterly line of Higuera Street; Thence along said line and along the northwesterly line of the offer to dedicate described in the document recorded in Volume 3020 of Official Records at page 1 in the Office of the County Recorder of said County North 270 41' 44", East 709.93 feet to the beginning of a curve to the left, having a radius of 20.00 feet; Thence continuing along line and along the southwesterly line of Prado Road, 84 feet wide, along the arc of said curve through a central angle of 90' 37' 00" a distance of 31.63 feet; x Page 157 of 1059 Ordinance No. (2026 Series) Page 2 Thence continuing along the southwesterly line of Prado Road North 62' 55' 10" West, 588.88 feet to a point on the northwesterly prolongation of the south line of the "24' strip to be dedicated to City of San Luis Obispo" shown on Parcel Map SLO-71-178 filed in Book 6 of Parcel Maps at page 70, in the Office of the County Recorder of said County; POINT OF BEGINNING; Thence continuing along the southwesterly line of Prado Road, North 620 55' 08" West, 1035.46 feet to the easterly right of way line of State Highway 101 as shown on the State of California Transportation Agency, Department of Public Works, Division of Highways — District 5, Right of Way Map 05-SLO-101 at post mile 26.9 on Sheet 31 of 32 sheets on file at the District 5 Office; Thence along said easterly right of way the following two courses: Thence South 880 05' 27", East 56.44 feet to an angle point located 300 feet right of station 718+46.90 as shown on said right of way map; Thence North 27' 46' 34" West, 60.00 feet to an angle point located 300 feet right of station 719+06.90 as shown on said right of way map and to the northeasterly right of way line of said Prado Road marked by a nail and tag inscribed "LS 4819" in concrete as shown on the Record of Survey filed in Book 65 of Licensed Surveys at page 41 in said Office of the County Recorder; Thence along said northeasterly right of way line, South 62' 55' 08" East, 1052.37 feet to the southwesterly corner of Parcel 2 of Parcel Map No. SLO-73-495 filed in Book 14 of Parcel Maps at Page 4 in said Office of the County Recorder; Thence South 66' 21' 48" West, 108.52' to the POINT OF BEGINNING. The Basis of Bearings for this description is the City of San Luis Obispo horizontal control network, January 2007, between control #8110 and control #8114, having a calculated bearing of South 300 05' 40" East. Designated points are published in a control inventory on file with the City of San Luis Obispo. Containing 86,165 square feet more or less. Also including that portion of Elks Lane in the City of San Luis Obispo, County of San Luis Obispo, State of California, described as follows: COMMENCING at a nail and tag inscribed "LS 4819" in concrete marking the northerly corner of the northeasterly right of way line of Prado Road as shown on the Record of Survey filed in Book 65 at Page 41 of Licensed Surveys in the Office of the County Recorder of said County, marking the angle point on the easterly right of way line of State Highway 101, located 300.00 feet right of station 719+06.90 as shown on the State of California Transportation Agency, Department of Public Works, Division of Highways — x Page 158 of 1059 Ordinance No. (2026 Series) Page 3 District 5, Right of Way Map 05-SLO-101 at post mile 26.9 on Sheet 31 of 32 sheets on file at the District 5 Office; Thence along said easterly right of way line North 16' 17' 06" West, 111.30 feet to an angle point marking the southeasterly corner of the land described in Parcel One of the Relinquishment of State Highway to the County of San Luis Obispo, Road V-SLO-2-E filed in Book 1258 of Official Records at page 19 in the Office of the County Recorder of said County, and the POINT OF BEGINNING; Thence northeasterly along the easterly line of said Parcel, North 18' 03' 55" East, 108.77 feet; Thence leaving said Parcel line, North 72' 02' 18" West, 55.00 feet to said State Highway easterly right of way line; Thence southerly along said right of way line the following three courses: South 170 57' 05" West, 22.21 feet; South 350 26' 34" West, 104.94 feet; South 800 57' 04" East, 87.38 feet to the POINT OF BEGINNING. The Basis of Bearings for this description is the City of San Luis Obispo horizontal control network, January 2007, between control #8110 and control #8114, having a calculated bearing of South 300 05' 40" East. Designated points are published in a control inventory on file with the City of San Luis Obispo. Containing 7,706 square feet more or less. Property owners shall be prepared to receive underground services by June 30, 2029. Overhead facilities shall be removed from public property by June 30, 2035. Property owners shall not incur any costs required for conversions. SECTION 2. A summary of this ordinance, approved by the City Attorney, together with names of the Council Members voting for and against it, shall be published at least five days prior to its final passage, in a newspaper published and circulated in this City. This ordinance will go into effect at the expiration of thirty days after its final passage. INTRODUCED on the 4th day of August, 2026, AND FINALLY ADOPTED by the Council of the City of San Luis Obispo on the day of , 202X, on the following vote: AYES: NOES: X Page 159 of 1059 Ordinance No. (2026 Series) Page 4 ABSENT: Mayor Erica A. Stewart ATTEST: Teresa Purrington City Clerk APPROVED AS TO FORM: J. Christine Dietrick City Attorney IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the City of San Luis Obispo, California, on Teresa Purrington City Clerk X Page 160 of 1059 053-041-067 PARCEL 2 - 68/PM/66 cco Q�co. WALTER BROS. o ^b; Z0 U0 CONSTRUCTION CO. INC o� ^ m 2 M v 0 POINT OF BEGINNING �620 S 66' 21' 48" W 108.52' SS �� 4p Rpq� Q� �_ F � S8$ 88 \ l 053-051-033 JK DEWAR PROPERTIES L.P. I A=90° 37' 00" L=31.63' R=20.00'�j1 /l LEGEND LEGAL DESCRIPTION AREA 86,165 SQUARE FEET± FOUND MONUMENT AS NOTED / \ 053-051-067 / CITY OF SLO / / 4014 OS89 0 / c I J PARCEL 1 -z- SLAL-91-102 pJAZ 50 PM 51 /N 053-051-072 / / CITY OF SLID / PARCEL 2 SLAL-91-102 MONUMENT / 50 PM 51 PER 114/RS/89 LOT1 17MB71 MONUMENT / PER 114/RS/89 GRAPHIC SCALE 0 75' 150' 300' / /co e� (IN FEET) N / 1IN=150FT 612 CLARION COURT SAN LUIS OBISPO, CA 93401 T 805 544-4011 F 805 544-4294 www.wallacegroup.us POINT OF COMMENCEMENT 620 18' 35" E 42.00' EXHIBIT" A " JOB No.: 1479-0007 UNDERGROUND UTILITY DISTRICT DRAWING: 1479-0007-LEGL-PRDO DRAWN BY: NS COUNTY OF SAN LUIS OBISPO, CA DATE: 04/15/26 SHEET 1 OF 3 OF EXHIBIT" A " SCALE: V=150' Page 161 of 1059 A Q� �7^ spy C-jJ o�O�� 2=0 p2ZO O NAIL AND TAG INSCRIBED "LS 4819" Oh J Z O AIT ^ (65 LS 41) O� �� 2 20 Cq \OZ �o GO2<U V /2 O ��O O T N 27° 46' 34" E 60.00' Q' Q o<c o \ O v ,`_ _ ^� 076 S 88° 05' 27" E 56.44' `S62°SS CITY OF SLO QT �8 F 4' WIDE STRIP \ ' �os13, S °8 °R w7�3S Oqp '46, 053-051-045 CITY OF SLO LEGEND LEGAL DESCRIPTION AREA 86,165 SQUARE FEET± FOUND MONUMENT AS NOTED GRAPHIC SCALE 0 75' 150' 300' (IN FEET) N 1IN=150FT 612 CLARION COURT SAN LUIS OBISPO, CA 93401 T 805 544-4011 F 805 544-4294 www.wallacegroup.us POINT OF BEGINNING S 66° 21' 48" W 108.52' 053-041-032 PARCEL 1 - 14/PM/04 PRADO PM LLC 053-051-033 JK DEWAR PROPERTIES L.P. EXHIBIT" A 11 JOB No.: 1479-0007 UNDERGROUND UTILITY DISTRICT DRAWING: 1479-0007-LEGL-PRDO DRAWN BY: NS COUNTY OF SAN LUIS OBISPO, CA DATE: 04/15/26 SHEET 2 OF 3 OF EXHIBIT" A " SCALE: V=150' Page 162 of 1059 LEGEND � I / F-1 LEGAL DESCRIPTION AREA 7,706 SQUARE FEET FOUND MONUMENT AS NOTED / / N / / N / O 44J / co Z 0 O /1- S 17° 57' 05" W 22.21' / N 72° 02' 18" W 55.00' o^O �p� A, / o1 J S 350 26' 34" W 104.94' N 18° 03' 55" E 108.77' (00 Qj��Q / ^ / POINT OF BEGINNING S 800 57' 04" E 87.38' POINT OF COMMENCEMENT NAIL AND TAG INSCRIBED "LS 4819" N 160 17' 06" W 111.30' (65 LS 41) GRAPHIC SCALE 0 75' 150' 300' \ A � (IN FEET) \Rpq 1IN=150FT 612 CLARION COURT SAN LUIS OBISPO, CA 93401 T 805 544-4011 F 805 544-4294 www.wallacegroup.us EXHIBIT" A 11 JOB No.: 1479-0007 UNDERGROUND UTILITY DISTRICT DRAWING: 1479-0007-LEGL-ELKS DRAWN BY: NS COUNTY OF SAN LUIS OBISPO, CA DATE: 04/15/26 SHEET 3 OF 3 OF EXHIBIT" A " SCALE: V=150' Page 163 of 1059 Page 164 of 1059 ORDINANCE NO. 767 (1978 Series) AN ORDINANCE OF THE CITY OF SAN LUIS OBISPO GRANTING TO PACIFIC GAS AND ELECTRIC COMPANY, ITS SUCCESSORS AND ASSIGNS, THE FRANCHISE (1) TO USE, FOR TRANSMITTING AND DISTRIBUTING ELECTRICITY SUITED FOR LIGHTING BUT FOR USE BY CONSUMERS FOR ANY AND ALL LAWFUL PURPOSES OTHER THAN LIGHTING, ALL POLES, WIRES, CONDUITS AND APPURTENANCES WHICH ARE NOW OR MAY HEREAFTER BE LAWFULLY PLACED AND "MAINTAINED IN THE PUBLIC STREETS AND PLACES WITHIN THE CITY OF SAN LUIS OBISPO, UNDER THAT CERTAIN FRANCHISE OF GRANTEE AC- QUIRED PURSUANT TO SECTION 19 OF ARTICLE XI OF THE CONSTITUTION OF THE STATE OF CALIFORNIA, AS SAID SECTION EXISTED PRIOR TO ITS AMENDMENT ON OCTOBER 10, 1911; (2) TO CONSTRUCT, MAINTAIN AND USE IN SAID PUBLIC STREETS AND PLACES ALL POLES, WIRES, CONDUITS AND APPURTENANCES WHEN- EVER AND WHEREVER SAID CONSTITUTIONAL FRANCHISE IS NOT NOW NOR SHALL HEREAFTER BE AVAILABLE THEREFOR, NECESSARY TO TRANSMIT AND DISTRIBUTE ELECTRICITY _ SUITED FOR, AND FOR USE BY CONSUMERS FOR, ANY OR ALL LAWFUL PURPOSES; AND (3) TO UTILIZE SAID POLES,' WIRES, CONDUITS AND APPURTENANCES IN SAID PUBLIC STREETS AND PLACES FOR TRANSMITTING ELECTRICITY FOR USE OUTSIDE THE BOUNDARIES OF THE CITY FOR ANY AND ALL LAWFUL PURPOSES, AND PROVIDING THE TERMS AND CONDITIONS OF THE FRANCHISE SO GRANTED. BE IT ORDAINED by the Council of the City of San Luis Obispo as .follows: AG:ktm 3/8/78 rev rev..6 %5 47�78 0 767 Page 165 of 1059 SECTION 1. DEFINITIONS. Whenever in this ordinance the words and phrases herein- after in this section defined are used, they shall have the respective meanings assigned to them in the following definitions: (a) The word "grantee" shall mean Pacific Gas and Electric Company, and its lawful successors or assigns; (b) The word "city" shall mean the City of San Luis Obispo, a municipal corporation of the State of California, in its present incorporated form or in any later reorganized, consolidated, enlarged or reincorporated form; (c) The word "streets" shall mean the public streets, ways, alleys and places as the same now or may hereafter exist within city, including State highways, now or hereafter established within city, and freeways hereafter established within city; (d) The Phrase "poles, wires, conduits and appurtenances" shall mean poles, towers, supports, wires, conductors, cables, guys, stubs, platforms, crossarms, braces, transformers, insulators, conduits, ducts, vaults, manholes, meters, cut- outs, switches, communication circuits, appliances, attach- ments, appurtenances and, without limitation to the foregoing, any other property located or to be located in, upon, along, across, under or over the streets of city, and used or useful in transmitting and/or distributing electricity. (e) The phrase "construct, maintain and use" shall mean to construct, erect, install, operate, maintain, use, repair, or replace; AG:ktm 3/8/78 -2- rev.6/5/78 Page 166 of 1059 (f) The phrase "constitutional franchise" shall mean the right acquired through acceptance by grantee or its prede- cessor in estate of the offer contained in the provisions of Section 19 of Article XI of the Constitution of the State of California, as said section existed prior to its amendment on October 10, 1911. SECTION 2. GRANT OF FRANCHISE. The franchise (1) to use, for transmitting and distributing electricity suited for lighting but for use by consumers for any and all lawful purposes other than lighting, all poles, wires, conduits and appurtenances which are now or may hereafter be lawfully placed and maintained in the streets within city under the constitutional franchise of grantee; (2) to construct, maintain and use in said streets all poles, wires, conduits and appurtenances whenever and wherever the constitutional franchise of grantee is not now nor shall hereafter be available therefor, necessary to transmit and distribute electricity suited for, and for use by consumers for, any or all lawful purposes; (3) to utilize said poles, wires, conduits and appurtenances in said public streets and places for transmitting electricity for use outside the boundaries of city for any and all lawful purposes is hereby granted to Pacific Gas and Electric Company, its successors and assigns. AG:ktm 3/8/78 -3- rev.6/5/78 rev.7/24/78 Page 167 of 1059 SECTION 3. RELOCATION OF FACILITIES. Grantee of this franchise shall relocate, without expense to city, any poles, wires, conduits and appurtenances theretofore installed, and then maintained or used under this franchise, if and when made necessary by any lawful change of grade, alignment or width of any streets by city, including the construction of any subway or viaduct, or any other conflict with a municipal govern- ment purpose. SECTION 4. TERM. Said franchise shall be indeterminate, that is to say, said franchise shall endure in full force and effect until the same shall, with the consent of the Public Utilities Commission of the State of California, be voluntarily surrendered or aban- doned by grantee, or until the state or some municipal or public corporation thereunto duly authorized by law shall purchase by voluntary agreement or shall condemn and take under the power of eminent domain, all property actually used and useful in the exercise of said franchise and situate in the territorial limits of the state, municipal or public corporation purchasing or con- demning such property, or until said franchise shall be forfeited for noncompliance with its terms by grantee. SECTION 5. CONSIDERATION. Grantee of said franchise shall during the term thereof pay to city a sum annually which shall be equivalent to two percent (20) of the gross annual receipts of grantee arising from the use, operation or possession of said franchise; provided, in case the AG:ktm 6/5/78 -4- Page 168 of 1059 State Legislature raises the minimum percentage allowable, the new rate shall apply; and provided, however, that such payment shall in no event be less than a sum which shall be equivalent to one-half percent (1/20) of the gross annual receipts derived by grantee from the sale of electricity within the limits of city under said franchise and said constitutional franchise. In addition to the foregoing, grantee shall pay to city within thirty (30) days of the issuance by the Public Utilities Commission of a certificate of convenience and necessity to exercise the franchise the sum of Ten Thousand Dollars ($10,000.00). If, at any time after the payment of said sum, it shall be adjudged that said franchise did not become effective or was or is invalid, or if the grantee shall, at any time, be prevented by the city or by judgment procured by any other person from exercising the same for any reason other than noncompliance with its terms by the grantee, then said sum of Ten Thousand Dollars ($10,000.00) shall be forthwith repaid by the city to the grantee. SECTION 6. REPORTS. Grantee shall file with the City Clerk within three (3) months after the expiration of the calendar year, or fractional calendar year, following the date of the granting hereof, and within three (3) months after the expiration of each and every calendar year thereafter, a duly verified statement showing in detail the total gross receipts of grantee during the preceding calendar year, or such fractional calendar year, from the sale of energy within city. Grantee shall pay to city within fifteen (15) days after the time for filing such statement, in lawful AG:ktm 3/8/78 -5- rev. 6/5/78 Page 169 of 1059 money of the United States, the aforesaid percentage of its gross receipts for such calendar year., or such fractional calendar year, covered by such statement. Any neglect, omission or refusal by grantee to file such verified statement, or to pay said percentage at the time and in the manner specified, shall be grounds for the declaration of a forfeiture of this franchise and of all rights of grantee hereunder. SECTION 7. AUTHORITY FOR GRANT. This franchise is granted under the Indeterminate Franchise Act of 1937 and pursuant to Article XIII of the Charter of the City of San Luis Obispo, adopted in 1955, and no other authority. SECTION 8. COMPLIANCE WITH LAWS. All facilities or equipment of grantee that grantee shall construct, maintain and use or remove, pursuant to the provisions of the franchise granted herein shall be accomplished in accordance with the ordinances, rules and regulations of city now or as here- after adopted or prescribed which are not in conflict with the paramount authority of such rules, regulations and orders as are promulgated or approved by or are filed with the Public Utilities Commission or other governmental authority having jurisdiction in the premises. SECTION 9. ADMINISTRATIVE PRACTICES. Grantee is herewith charged with the responsibility of preparing, with the cooperation of city, a manual of administrative AG:ktm 6/5/78 -6- Page 170 of 1059 practices which shall Govern the installation and removal of grantee's facilities in the streets of city which shall include, but not be limited to, cathodic protection practices. Once each year, com- mencing with the first full calendar year of the franchise granted herein, it is to be the joint responsibility of grantee and city to review and update such administrative practices. Both grantee and city are charged with the duty to review and update such admin- istrative practices by a method of mutual cooperation which shall take into consideration the reasonable needs and convenience of each party; provided that said administrative practices and the terms and conditions thereof shall be at all times subject to approval of the City Council as expressed by appropriate legis- lative action, and shall not conflict with the paramount authority of such rules, regulations and orders as are promulgated or approved by or are filed with the Public Utilities Commission or other govern- mental authority having jurisdiction in the premises. Following the preparation of said manual, and its approval by the City Council, it shall govern the practices of the grantee in its installation and removal of grantee's facilities in the streets of city. SECTION 10. CITY RESERVED POWERS. (a) City reserves the right for itself to lay, construct, erect, install, use, operate, repair, replace, remove, relocate, regrade or maintain below surface or above surface improvements of any type or description in, upon, along, across, under or over the streets of the city. City further reserves the right to re- locate, remove, vacate or replace the streets themselves. If the AG:ktm 6/5/78 -7- Page 171 of 1059 necessary exercise of the aforementioned reserved rights is made necessary in order to accommodate a municipal government purpose and conflicts with any poles, wires, conduits and appurtenances of grantee constructed, maintained and used pursuant to the pro- visions of the franchise granted hereby, whether previously con- structed, maintained and used or not, grantee shall, without cost or expense to city after written notice from the City Administative Officer, or his designated representative, and request to do so, begin the physical field construction of changing the location of all facilities or equipment so conflicting. Grantee shall proceed promptly to complete such required work. (b) Irrespective of any other provision of this ordinance, grantee's right to construct, maintain and use, or remove poles, wires, conduits and appurtenances thereto shall be subject at all times to the right of city, in the reasonable exercise of its police power in response to a direct and immediate threat to the health or safety of the public, to require the removal or relocation of said poles, wires, conduits and appurtenances thereto at the sole cost and expense of grantee. SECTION 11. REPAIR COSTS. Grantee shall pay to city on demand the cost of all repairs to city property made necessary by any of the operations of grantee under the franchise granted hereby provided, however, that grantee may make repairs to streets, sidewalks, curbs and gutters itself at its own cost in accordance with city specifi- cations if the same can be done without undue inconvenience to the public use of the streets. AG:ktm 6/5/78 -8- Page 172 of 1059 SECTION 12. FORFEITURE, This franchise is granted upon each and every condition herein contained, and shall be strictly construed against grantee. Nothing shall pass by the franchise granted hereby to grantee unless it be granted in plain and unambiguous terms. Each of said conditions is a material and essential condition to the granting of the franchise. If grantee shall fail, neglect or refuse to comply with any of the conditions of the franchise granted hereby, and if such failure, neglect or refusal shall continue for more than thirty (30) days after written demand by the City Administrative Officer for compliance therewith, then city, by the City Council, in addition to all rights and remedies allowed by law, thereupon may terminate the right, privilege and franchise granted in and by this ordinance, and all the rights, privileges and the franchise of grantee granted hereby shall thereupon be at an end. Thereupon and immediately, grantee shall surrender all rights and privileges in and to the franchise granted hereby. No provision herein made for the purpose of securing the enforcement of the terms and conditions of the franchise granted hereby shall be deemed an exclusive remedy or to afford the ex- clusive procedure for the enforcement of said terms and conditions, but the remedies and procedure outlined herein or provided, including forfeiture, shall be deemed to be cumulative. SECTION 13. ACQUISITION AND VALUATION. Nothing in this ordinance or in the franchise granted hereby shall be construed as in any way impairing city's rights AG: ktm 6/5/78 -9- Page 173 of 1059 to acquire property of grantee through the exercise of city's power of eminent domain, or through voluntary agreement between city and grantee. In the event that city chooses to exercise its power of eminent domain, it shall do so in accordance with the procedures provided by the general law of the State of California for the condemnation of public utility property. The valuation of such property for condemnation purposes shall be made in accordance with such general law. SECTION 14. UNDERGROUNDING. (a) It is the city's intent to underground all utilities as expeditiously as possible. (b) Presently, grantee is engaged in a program of con- verting to underground certain of its facilities in accordance with Decision No. 73078 of the California Public Utilities Com- mission. At this time, said decision requires grantee to budget prior to the end of each calendar year, certain sums of money for said program for the next succeeding year and allocate these sums to undergrounding projects in the various governmental juris- dictions throughout grantee's entire service territory on the basis of the number of customers in each governmental jurisdiction. Grantee shall at all times use its best efforts to accomplish as much conversion in the city as may be accomplished through the allocation or .reallocation of funds by the California Public Utilities Commission pursuant to Rule 20. AG:ktm rev. 7/24/78 -10- Page 174 of 1059 (c) In addition to the foregoing, grantee agrees to per- mit city to install its conduits in grantee's trenches upon pay- ment of city's proportionate share of trenching costs. Said conduits shall include, but not be limited to, conduits for street lighting, traffic signals and fire alarm systems. SECTION 15. HOLD HARMLESS. Grantee of the franchise granted hereby shall indemnify, save and hold harmless, city and any officers and employees thereof against and from all damages, judgments, decrees, costs and expen- ditures which city, or such officer or employee, may suffer, or which may be recovered from, or obtainable against city, or such officer or employee, for, or by reason of, or growing out of or proximately resulting from the exercising by grantee of any or all of the rights or privileges granted hereby, or by reason of any act or acts of grantee or its servants or agents in exercising the franchise granted hereby, and grantee shall defend any suit that may be instituted against city, or any officer or employee thereof, by reason of or growing out of or proximately resulting from the exercise by grantee of any or all of the rights or priv- ileges granted hereby, or by reason of any act or acts of grantee, or its servants or agents, in exercising the franchise granted hereby. SECTION 16. EFFECTIVE DATE. This ordinance shall become effective thirty (30) days after its final passage unless suspended by a referendum petition filed as provided by law. AG:ktm 6/5/78 -11- Page 175 of 1059 SECTION 17. WRITTEN ACCEPTANCE. The franchise granted hereby shall not become operative until written acceptance thereof shall have been filed by the grantee with the City Clerk. SECTION 18. PUBLICATION AND PUBLICATION COSTS. This ordinance, together with the ayes and noes, shall be published once in full, at least three (3) days prior to its final passage in the Telegram -Tribune, a newspaper published and circulated in said city. The grantee of said franchise shall pay to the city a sum of money sufficient to reimburse it for all publication expenses incurred by it in connection with the granting thereof; such payment to be made within thirty (30) days after the city shall have furnished such grantee with a written statement of such expense. INTRODUCED AND PASSED TO PRINT by the Council of the City of San Luis Obispo at a regular meeting thereof held on the 18th day of July , 1978, on motion of Councilman Jorgensen, seconded by Councilman Settle , and on the following roll call vote: AYES: Councilmen Dunin, Jorgensen, Petterson, Settle & Mayor Schwartz NOES: None ABSENT: None ATTEST: Ole- AG:ktm 3/8/78 rev.6/5/78 -12- Page 176 of 1059 Approved as to form: Approved as to content: WENDT, MITCHELL, SINSHEIMER, de la MOTTE & LILLEY City Attorney qp�� - �- -- By Allen Grimes City Administrate Officer Director of Public Services City Eng'neer i erector inanceJ AG:ktm 6/5/78 -13- Page 177 of 1059 ORDINANCE NO. 767 FINALLY PASSED this lst day of August 1978 , on motion of Councilman Settle seconded by Councilman Jorgensen on the following roll call vote: AYES: Councilmen Jorgensen, Petterson, Settle and Mayor Schwartz NOES: None ABSENT: Councilman Dunin ATTEST: J. zpa rick, CITY CLERK th E. Schwartz, MAYOR Page 178 of 1059 At consor Supplemental Value Analysis Memorandum Date: June 3, 2026 Project: 05-1H640 US101 and Prado Road Interchange To: Mr. Matt Horn, PE, City Major Projects Manager City of San Luis Obispo From: Dace Morgan, PE Re: Supplemental Value Analvsis Memorandum Introduction The City contracted with Consor to review, validate, and develop additional value analysis recommendations for the US101 and Prado Road Interchange project. The goal was to review the Hybrid Value Analysis (VA) prepared by VMS in the Spring 2023 and implement recommendations, as appropriate. In addition, Consor's scope included conducting three design charrettes with City and Caltrans staff to examine if additional value items could be realized. The Consor team included a traffic sensitivity study to test the sensitivity of the number of traffic lanes required (width) and configuration of the Prado Road corridor. The team approached the project area from a functional use and context perspective and divided the limits into three segments that make up the corridor from Dalidio Drive to Higuera Street. The team looked at several configuration scenarios and ran hydraulics modeling to optimize the layout of the supports for the overcrossings and ramp structures. The outcome of the design charrettes, completing a traffic sensitivity analysis using the current future City land uses, and further refinement of the hydraulics and structures layout, the team was able to realize approximately $20 million in savings to the project. Hybrid Value Analysis The City realized that the construction cost of the US101 and Prado Road Interchange was becoming prohibitively expensive. In the Spring of 2023, the City hired VMS to facilitate and prepare a Hybrid Value Analysis with the goal of looking for opportunities to reduce overall project costs and make schedule saving recommendations. The VA team identified the following items to be considered by the design team: 1. Reduce the maximum speed on Prado Road to 35 mph (this was implemented as part of the PA&ED and Caltrans approved the Design Standard Decision Document for this revision) 2. Reduce lane and shoulder widths where practical 3. Use CIDH columns in lieu of driven piles and pile caps 4. Use longer spans and fewer columns with precast I -girders in lieu of CIP griders 5. Leave existing sewer main on current Elks Lane alignment in lieu of relocation (this was rejected by project stakeholders and was not implemented) 6. Utilize recycled and/or reclaimed materials in project Project Number • Mont Year • t f 1059 Pr jea VP The decision was made to implement the appropriate and applicable recommendations during the PS&E phase of the project and not incorporate them into the PA&ED phase. Once under contract, Consor reviewed the recommendations and discussed the implementation of them with City staff. City staff indicated that items 1- 4 and 6 should be implemented to the extent possible. Revalidation of Value Analysis Consor began developing conceptual roadway and structure layouts to incorporate the recommendations from the previous VA work. As part of the revalidation phase, Consor conducted three design charrettes that included City staff (Wyatt Banker-Hix, Luke Schwartz, Brian Nelson), Caltrans (Paul Valadao), and Consor team (Brent Lemon, Dace Morgan, Brent Harrison, Scott McCauley, Jim Damkowitch (DKS), and Brian Ray (Sunrise)). The purpose of the design charrettes was to review VA recommendations and look at the Prado corridor through a performance -based design approach instead of the more traditional capacity/demand design theories. The project stakeholders determined performance criteria and ranking the criteria. The most important criteria were to not impact the operations of US101 mainline (i.e. no back up on US101 mainline), reduce crash severity on Prado, Mainline Ramp merge and diverge, Pedestrian level of stress, Emergency Vehicle response, and Safety queueing issues. The least important criteria were vehicular Delay during non -peak periods, Goods movement at Prado Road and Elks Lane Intersection, and Level of Service. With these criteria defined, the team prepared a traffic sensitivity analysis and compared a four -lane corridor with a two-lane corridor and roundabout and signal intersection controls. See attached performance ranking matrix. New AM and PM peak traffic counts were collected at 15 locations (see attached Supplemental Traffic Operations Memorandum for locations) in May 2025 by the Consor team. These counts included bikes and pedestrians. The peak hour volume sets used for this work were based on the most recent travel demand modeling developed by Central Coast Transportation Consultants on behalf of the City and included the current land use build out of the City's general plan. The travel demand outputs were post -processed using the May 2025 counts. For 2050, the ped and bike counts were manually adjusted to reflect the anticipated increase in bike and ped activity as a result of the project improvements. Reducing the entire Prado corridor to two lanes resulted in unacceptable delays and congestion that spilled back to Higuera (PM peak) to the east and the Froom Ranch roundabout (AM peak) to the west. Through iterations, it was determined that a four -lane section from the Higuera/Prado intersection to the NB ramp terminal intersection and then a two-lane section from the NB ramp terminal to the Froom Ranch/Dalidio Drive roundabout would result in acceptable operations during peak and non -peak hours. The Prado corridor would experience some delays and congestion in the peak hours starting in 2045, assuming full land use build out of the City's current general plan. As part of the design charrette process, the design team proposed replacing the combination sidewalk and Class IV protected bike paths on both sides of the corridor with a multi -use bidirectional pathway on the south side of Prado and a 6-foot-wide sidewalk on the north side of Prado Road. This cross section for bikes and pedestrians closely matches the facilities throughout the San Luis Ranch development. On Nov 4, 2025, the City Council approved the reconfiguration of the Prado Road corridor from Higuera Street to Froom Ranch/Dalidio Drive roundabout. The City approved reconfiguration is shown in Figure 1 below: D218721CA.00 • June 2026 • City of San Luis Obispo US101 and Prado Road Interchange • 2 Page 180 of 1059 Figure 1: Preferred Alternative - 2-lane overcrossing The construction cost for the bridge and roadway improvements in 2026 dollars with a 30% contingency was approximately $80 million. Structures Value Analysis The largest cost of the project is the bridge structure. During our preliminary analysis, Consor determined that for every 1 foot of width of bridge structure reduced, the construction cost would be reduced by approximately $500,000. Therefore, the team focused on narrowing the bridge structure with the reduction of lane widths, number of lanes, and the reconfiguration of the multi -modal features. The VA recommended lengthening spans from the 100-foot spans in the PA&ED phase. Consor increased the span lengths to 150 feet for the Prado Road structures. We also made it a priority to eliminate a support within the US 101 center median to simplify construction and impacts to Caltrans. Realizing that bridge spans are more costly than retaining walls and the project area is within a FEMA floodplain, the Consorteam began developing and refining the hydraulics model for the project while trying to balance increases to the 100-year water surface elevation, construction costs of a fully elevated structure, and visual impacts. Through optimization, the design team was able to reduce the total amount of bridge structure from approximately 2,550 feet (as conceived in the Project Report) to approximately 1,250 feet. Retaining walls would be utilized where feasible at the western and eastern ends of the Prado Road overcrossings and at the beginning and the end of the northbound ramp structures. During the hydraulics modeling, it was determined that placing the northbound ramp terminal intersection on an island enclosed by octagonal retaining structure (MSE island wall) minimized floodplain impacts to the southeast side of the project. The MSE island wall splits the overcrossing and the northbound ramps into four separate structures, provides cost savings, reduces long term maintenance for the bridge structures, and more predictable seismic performance as compared to the previously proposed structure and more complex elevated intersection. The bridge superstructure types will be finalized during the Bridge Type Selection process. Currently, the team is proposing two superstructure types, a cast -in -place (CIP) concrete post tension box girder and a precast prestressed (PC/PS) California wide flange girder. Both structure types provide a cost-effective solution for the overcrossing of US 101. The PC/PS option would not require falsework over US 101 during construction; however, the CIP option provides flexibility for incorporating the flare for the northbound ramp intersection and the CIP would be consistent with the adjacent Prado Interchange structures and other interchange structures in the area. The eastern Prado Road overcrossing and the northbound ramp structures are better suited for the CIP option. The bridge is recommended to be supported on large diameter cast -in -drilled hole (CIDH) piles. This is consistent with the previously prepared VA study recommendations. D218721CA.00 • June 2026 • City of S9 Luis Uspoo 1059 pf US101 and Prado Roadt,�an J Hydraulics and Hydrology Modeling A two-dimensional (21D) hydraulic model was developed to assess pre- and post -Project conditions for the base flood. Areas within the project, such as the Prado Road intersection with the northbound ramps and Elks Lane, along Elks Lane, and portions of the northbound off -ramp have experienced flooding in the past. The hydraulic modeling results for the Project indicate that the flooding along the northbound ramps and along Prado Road would be alleviated, the proposed bridge structures have adequate freeboard in both the 100-year and 50-year flood events. The hydraulic modeling results indicated the average water surface elevation (WSE) increases of 0.1 foot or less along FEMA cross sections, which meets both City and FEMA standards and are insignificant impacts. There are point locations of larger WSE increases at the Water Resources Recovery Facility (WRRF) (0.7 feet increase) and an area adjacent to the western end of the project (2.4 feet). This area will likely require additional hydraulic analysis and grading during the PS&E phase of the project. The new bridge structures and walls are being designed to accommodate the proposed scour for both the 100-year base flood and the 200-year check flood event. The design criteria is that the bridge maintain stability during the 200-year check flood event. Stormwater Management and Drainage Considerations Stormwater management and drainage were two items that were not developed as part of the PA&ED phase of the project. As part of Phase I, the Consor Team prepared mapping to identify the existing drainage patterns within the project footprint. This allowed the design team to better understand the existing and historic drainage patterns and determine a baseline for the future project improvements and their impact on the existing stormwater features. It was determined that there is currently flow from public roads flowing into stormwater treatment and retention basins that were constructed as part of the RTA, Homeless Service Center, and WRRF improvements. Because the RTA and Homeless Service Center constructed portions of the new realigned Elks Lane, their developments treated the stormwater in basins within their property. This is similar to the approach taken as part of the WRRF improvements. See attached map for existing drainage patterns within the project footprint. The proposed project will result in 0.94 acres of net new impervious surface (NNI) and 1.42 acres of replaced impervious surface (RIS) within Caltrans' right-of-way; and 1.73 acres of NNI and 2.86 acres of RIS within City's right-of-way. Additionally, there will be 0.14 acres of bike lane on existing roadway within Caltrans' right-of-way, which are exempted from NIS. The Project will lose 0.03 acres of treated impervious area from existing treatment BMPs. Therefore, the Project is required to treat 2.25 acres of new impervious surface (NIS) within Caltrans' right-of-way, and 4.59 acres of NIS within City's right-of-way. The table below shows the breakdown of the impervious surfaces and treatment goal for the project within Caltrans' and City's rights -of -way. The current analysis indicates that overall, the project is treating a surplus amount of impervious area; however, the treatment area within the Caltran's right of way is greater than required while the area within City's right of way is at a deficit. The City's existing basins will receive an additional 2.12 acres new impervious areas in total; and the design team currently assumes the basins have the sufficient capacity to accommodate the additional treatment at this phase. The City's Stormwater Control Measures are currently receiving 0.46 acres of impervious area from Caltrans' right-of-way, which the City is not currently taking credit for. The proposed project is located next to developed areas such as Regional Transit Authority, 40 Prado Homeless Service Center, and City of San Luis Obispo Water Resource Recovery Facility, constraining the project to a limited area for proposed treatment. The design team will be working D218721CA.00 • June 2026 • City of San Luis Obispo US101 and Prado Road Interchange • 4 Page 182 of 1059 with City and Caltrans staff in the PS&E phase of the project to determine the acceptability of the proposed stormwater treatment solution. *Excludes 0.14 acres for bike paths **Includes additional treatment area of 0.03 acres New storm drain facilities will be constructed as part of the project. A new system will be installed in the area of the new Prado Road/Elks Lane intersection, modifications will be made to the existing storm drain system near the existing northbound on-ramp/existing Elks Lane intersection to allow stormwater to continue to flow to the low point between the northbound off -ramp and northbound US 101. This water will be treated in BMP No. 1. See attached exhibit for locations of the proposed storm drain systems. City Wet Utility Relocations The VA contemplated not relocating the City's sewer main to the realigned Elks Lane. This recommendation was ultimately rejected by the project stakeholders. The Consor design team has met with City Utilities staff to discuss their relocation plans for both the sewer and water mains in the vicinity of the project. Currently, the design includes relocating sewer and water along the new alignment of Elks Lane. With the realignments, City Utility staff will be able to access and maintain these important services without being impeded by the new Prado Road overcrossing. The construction cost for the relocation of these services is approximately $3,000,000. See attached exhibit for the relocation of the City's sewer and water facilities. In April 2026, Consor evaluated four alternatives to address impacts to the existing 12-inch diameter water crossing of US 101 near the Prado Road interchange. The construction of the MSE Island at the northbound ramp intersection will place the existing 12-inch ductile iron pipe under excessive fill material presenting a challenge for future maintenance. The transmission line is required to maintain critical east — west water system connectivity for the City. The analysis looked at alternatives for reconstructing the crossing including factors such as constructability, cost, operational impacts, permitting/easements, and long-term maintenance. Four options were evaluated to address the transmission main crossing. Option 1 proposes a trenchless jack -and -bore installation beneath US 101 outside of the project area, minimizing surface disruption but requiring specialized construction, Caltrans permitting, additional environmental review, and potential easements, with an estimated construction cost of approximately $1.15 million. Option 2 extends a transmission main that currently terminates at the end of Calle Joaquin using open -cut construction to create an alternate routing; this option has greater surface impacts, requires multiple easements, and an environmental review, with an estimated construction cost of about $2.3 million. Option 3 routes the waterline within the bridge structure in a steel casing, leveraging bridge construction but introducing added complexity and long-term maintenance considerations, at an estimated construction cost of D218721CA.00 •June 2026 • c"y of s Luis of �Pf 1059 US101 and Prado Road I tean� approximately $1.19 million. Option 4 extends existing casing along the existing Prado Road alignment beneath the MSE Island wall, representing the simplest and most cost-effective solution at construction cost of roughly $75,000, but relying on the existing pipeline and casing being in acceptable condition. Consor recommends Option 4 (Extending casing through the MSE Island wall) as the preferred approach, contingent on verification that the existing pipeline and casing are in good condition. This option provides the most cost-effective and least disruptive solution within the current project scope while meeting the objective of providing a maintainable east -west water system connection. The City may consider implementing one of the higher -cost alternatives in the future to enhance system redundancy and east — west connectivity. Full water -line alternatives memorandum is attached. Utility Relocations/Undergrounding The City desires to underground the overhead utilities along the Prado Road corridor as part of the interchange project. The Consor team has been working with PG&E, AT&T, Charter, and Astound to establish undergrounding plans. In general, the utilities located within the Prado Road corridor do not have prior rights and would be required to relocate their overhead facilities outside of the project limits at their own cost. The undergrounding of the utilities is above and beyond the costs outline in Franchise and Encroachment agreements. In general, the utilities determine the cost to underground their facilities and then provide the City with credit for the cost of relocating and staying overhead. At this time, we are working closely with PG&E to determine the cost of undergrounding their facilities as this will be the largest of the overhead utilities. During our Utility outreach, it was determined that Phillips 66 has two 8-inch oil lines within a Joint Use Agreement (JUA) with Caltrans. This JUA dates to before US 101 was constructed and therefore, Phillips 66 has prior rights and will require reimbursement for the relocation of their facilities. The Consor team met with Phillips 66 and reviewed the proposed alignment for the northbound off -ramp, and the oil lines are in conflict and will need to be relocated as part of this project. The cost of the relocation is not known currently. Caltrans Revisions to Ramp Terminal Intersection The design team has been working closely with Caltrans to address their concerns with the two-lane overcrossing, the geometric layout of the northbound ramp intersection, and the hydraulic impacts to the structure, particularly scouring at the MSE island. In conjunction with our traffic consultants, DKS, we have satisfied Caltrans Traffic Operations that the two- lane overcrossing and northbound ramps will operate at an acceptable level. There was a concern that reducing the Prado Road overcrossing from 4-lanes to 2-lanes would have an adverse effect on the adjacent Madonna and Los Osos Valley Road (LOVR) interchanges. DKS prepared a comparison of future traffic volumes for all three interchanges and determined that the 2-lane overcrossing had a minor to no impact on the operations of the Madonna and LOVR interchanges in the design year of 2050 based on full general plan build out. The northbound ramp intersection will require the widening of the Prado Road west overcrossing to accommodate sight distance and trucks turning east and west from the northbound off -ramp onto Prado Road. The bridge structure will be flared from a width of 65'-4" to 89'-10" on the west side of the ramp intersection. See Figure 2 below for the reconfiguration of the ramp intersection. D218721CA.00 • June 2026 • City of San Luis Obispo US101 and Prado Road Interchange • 6 Page 184 of 1059 a z 0 m z M Figure 2: Revised/Widen Northbound Ramp Intersection Caltrans issued a Structure Technical Policy (STP 2.6) for hydraulic design of structures over waterways in December 2025. STP 2.6 requires that structures over waterways be designed to withstand a scour event based on a 200-year flood. The Consor team requested a variance from this requirement on the basis that our structure is in a floodplain and does not span a creek or river. Unfortunately, Caltrans Structures Headquarters Hydraulics did not grant this variance. They agreed that the footing for the abutments within the MSE island do not need to be placed at the elevation of the depth of scour. The revisions to the structures to accommodate the widening of the northbound ramp intersection and STP 2.6 has resulted in an increase to the project of approximately $2.5 million. Conclusion The goal of the Value Analysis Revalidation phase of the project was to incorporate VA recommendations from the PA&ED phase and continue to look for cost savings in the project design elements. The US 101 and Prado Road Interchange project is a necessary transportation improvement project for the improvement of local circulation, the improvement the pedestrian and bicycle connectivity, and the continued growth of the City of San Luis Obispo; however, the project needs to be cost effective and affordable. The reduction of the overcrossing to two travel lanes, the reconfiguration of the multi -modal facilities, the reduction of length of bridge structure, and the lowering of the vertical profile have resulted in cost reductions. The design team continues to keep construction costs at the forefront of our minds. The project is still in the early stages of design and there are cost impacts that are not known at this point, in particular the cost to underground utilities, relocation costs for the Phillips 66 oil lines, and obtaining the necessary right of way. As these costs become known, they will be shared with City staff. Below are construction costs for the roadway, structures, and wet utility relocations. The structure costs do include an allowance for aesthetic treatments The costs below include a 25% contingency and are based on 2026 dollars. D218721CA.00 •June 2026 •City of S Luis Off 1059 US101 and Prado Road I tean� Attachments: 1. Performance Ranking Matrix 2. Supplemental Traffic Operations Memorandum 3. Existing Stormwater Map 4. Proposed Stormwater Control Measures 5. Proposed Drainage Improvements 6. Proposed Water and Sewer Relocations 7. Water line relocation cost analysis memorandum D218721CA.00 • June 2026 • City of San Luis Obispo US101 and Prado Road Interchange • 8 Page 186 of 1059 lilli' III �o W a y 1104-MVIIII I :» :01 10111111411111 :1111110L 191mlixid W1 75 1:1 0l lexaYTI VI--13 C �11 11 :(chv*4414111 11v I *Role] �A GAD TRAFFIC ANALYSIS DATE: May 15, 2026 TO: Brent Lemon, PE I Consor Dace Morgan, PE I Consor FROM: Jim Damkowitch I DKS Joel Rabinovitz, PE I DKS SUBJECT: 05-1H640 US101 and Prado Road Interchange -- Supplemental Project #24989-000 Project Report The following traffic analysis was completed to support the US101 and Prado Road Interchange project. The relative performance of various design elements of the proposed project were analyzed under AM/PM peak hour 2050 future year conditions and compared across the following three performance metrics: • Vehicular Level of Service (based on Highway Capacity Manual 71h Edition - HCM 7 grades using static and simulation delay results) • Vehicular Delay (using both static and simulation modeling) • Vehicular 95th Percentile Queue (based on simulation modeling) The peak hour volume sets used for these operational determinations were based on the most recent travel demand modeling developed by the City of San Luis Obispo. All demand profiles reflect future mode shifts to transit. Pursuant to NCHRP Report 765 Analytical Travel Forecasting Approaches for Project -Level Planning and Design, 2014, travel demand model outputs were post -processed using traffic counts collected in May 2025. The traffic counts include pedestrians and bicyclists. For the Future Year (2050) Build condition these pedestrian/bicycle counts were manually adjusted to reflect the anticipated increase in pedestrian/bicycle activity to result from the project (i.e., overcrossing connectivity and planned bicycle and pedestrian facilities in the proposed project). SHAPING A SMARTER TRANSPaRTATIQN EXPERIENCE" Page 188 of 1059 The focus of the analysis is on Prado Road at the following two intersections: 1. Prado Road / US 101 NB Ramps 2. Prado Road / Elks Lane Currently Elks Lane and the US 101 NB ramps intersect at an all -way -stop. With the extension of Prado Road to Froom Ranch Way (Figure 1), Elks Lane would be realigned with the City's new Water Resource Recovery Facility (WRRF) and Corporation Yard entrance. s , a,�r • 1 %)= - Prado Road Extension + Elks Lane Realignment 41 AP 1 if FIGURE 1: STUDY AR EA I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 2 Page 189 of 1059 A value engineering (VE) process is a structured, multidisciplinary review used to confirm that a project provides the needed functions safely, reliably, and efficiently while improving value and managing cost. For the Prado Road interchange, the process included reviewing the previously identified need for a four -lane Prado Road cross-section over US 101, defining the essential project functions, identifying design constraints and opportunities, developing and screening potential design refinements, and comparing alternatives based on operations, safety, constructability, right-of-way, environmental effects, cost, and long-term performance. During the VE process, the team looked at a 4-lane and 2-lane overcrossing, different placement of pedestrian and bicycle facilities, different control types (signal and roundabout), right-of-way impacts, and cost. The GAD Design (2-Lane Overcrossing) is the culmination of the VE process. From the VE design process, the preferred Build design (GAD Design 2-Lane Overcrossing) shown in Figure 2 includes a two-lane overcrossing over US 101, four lanes extending from east of the US 101 NB ramps to Higuera Street, shoulder and sidewalk on the north side of Prado Road, and a shoulder and two-way mixed -use path (MUP) on the south side. This alternative includes signals at the US 101 NB ramps and Elks Lane intersections, with the westbound right -turn at the US 101 NB ramps intersection controlled by the signal as well. With the bi-directional MUP on the south side of Prado Road, the northbound right turns onto Prado Road were assumed to operate as no right -turn on red (RTOR). The US 101 northbound on -ramp would be a single lane and add an auxiliary lane to US 101 between the Prado Road and Madonna Road interchanges, resulting in a weave condition. The addition of the auxiliary lane was approved by City Council on November 4, 2025. I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 3 Page 190 of 1059 rn LO 0 vl- - 0 N (u 0- ID N O N } Q } J Q z Q Z u LL LL Q 0 Q m w U w W • (D z a = > O W Z a U LU ~ z o J Z M Q O O Q < � W � � a a 0 Q N W C7 LL 0 V) D The methodologies used for the purpose of analyzing the various design elements of the proposed project alternatives are described below. Two forms of analysis were applied: static and stochastic. The static analysis is primarily based on methods described in the Highway Capacity Manual (HCM). Static analysis uses a fixed data input set along with a set of equations to develop a deterministic result versus stochastic analysis which uses a set of inputs with multi -run variance to derive a set of measured rather than calculated results (i.e., microsimulation). The SYNCHRO modeling software was applied for static analyses while the VISSIM modeling software was applied for stochastic operational determinations. Freeway analysis was performed using the Leisch method, which is also a static analysis. HIGHWAY CAPACITY M ANALYSIS The operation or performance of roadway facilities is commonly described in terms of Level of Service (LOS). LOS is a qualitative measure of effectiveness describing traffic operations based on such factors as speed, travel time, delay, and freedom to change lanes for all vehicles. Six levels are defined from LOS A, as the best -operating conditions, to LOS F, or the worst operating conditions. LOS E represents "at -capacity" operations. Study intersections were analyzed to determine their LOS based on the definitions and formulas presented in the Highway Capacity Manual 7th Edition (HCM 7) as implemented by the SYNCHRO analysis software. Table 1 presents the LOS criteria for intersections in accordance with the HCM 7 methodology. TABLE 1: INTERSECTION LEVEL OF SERVICE CRITERIA - SIGNAL LEVEL OF SERVICE (LOS) TOTAL DELAY PER VEHICLE (SECONDS) A < 10 B > 10 and < 20 C > 20 and < 35 D > 35 and < 55 E > 55 and < 80 F > 80 Notes: A. HCM 7, Chapter 19 (Signalized Intersections) I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 5 Page 192 of 1059 MICROSIMU ATION ANALYSIS Microsimulation analysis was conducted using the VISSIM modeling software to better reflect the effects of the close intersection spacing as well as lane utilization that the HCM methodologies do not specifically address. The models were developed, and analysis was conducted in accordance with the FHWA guidelines for microsimulation analysis'. It should be noted that the VISSIM models used for this analysis were not calibrated to existing conditions. However, the Existing configuration (no overcrossing, all -way stop) and future configuration (with overcrossing, signal or roundabout) are different enough that much of the calibration for the Existing condition (e.g., how drivers yield at the stop sign) would not be useful for the Future Build conditions. The driver behavior and other model parameters were based on previous models developed by DKS for similar facilities. Delay results from the microsimulation analysis are compared to HCM LOS criteria for intersections for the purpose of consistency with other analysis in this report. QU NG 95th percentile queue results are defined as the length of the queue which is exceeded five percent of the time during the analysis time period. The 95th percentile queue is useful in determining the appropriate storage requirements such as length of turn pockets but is not representative of what an average driver would experience during their commute. SYNCHRO was used to identify the average and 95th percentile vehicle queues for approaching traffic for the future peak volumes. The 95th percentile queue in SYNCHRO is a calculation of the maximum back of queue with 95th percentile traffic volume, and not an actual observed queue. VISSIM was also used to estimate the average and 95th percentile vehicle queues for approaching traffic for each study intersection for the one -hour system peak hour. To calculate 95th percentile queues, queue length data was collected from VISSIM using queue counters on critical approaches with a 120-second interval to reflect queues that form while traffic flow is impeded. The average and 95th percentile queue was then calculated using a percentile function in Excel. DKS considers micro -simulation as a superior approach for queuing analysis given its ability to more accurately reflect the operational interaction of adjacent intersections, in particular, closely spaced intersections. It is also better at reflecting the interactions of pedestrians and bicyclists at intersections of all control types. 1 Traffic Analysis Toolbox Volume III: Guidelines for Applying Traffic Microsimulation Modeling Software. Federal Highway Administration (FHWA). August 2003. I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 6 Page 193 of 1059 CONGEST ON The simulation model was also used to measure motor vehicle delay relative to desired speed as an indicator of congestion. The delay is measured as a percentage of travel time for a given roadway segment. The colors shown indicate the following approximate queue states: • Dark Green = Free flow, no delay (delay less than 5 percent of travel time) • Light green = Slight slowing (5-20 percent) • Yellow = Increased slowing, but not yet stop and go (20-40 percent) • Orange = Furthest extend of stop and go queues, rough approximation of 95t" percentile queue (40-60 percentile) • Red = Fluctuates between low -speed flow and stopped queue (60-80 percentile) • Dark Red = Stop and go queue during the entire 15-minutes peak interval (delay greater than 80 percentile of travel time) FUT FORECASTS The peak hour volume sets used for these operational determinations were based on the most recent travel demand modeling developed by the City of San Luis Obispo. All demand profiles reflect future mode shifts to transit. Pursuant to NCHRP Report 765, travel demand model outputs were post - processed using traffic counts collected in May 2025. The traffic counts include pedestrians and bicyclists. For the Future Year Build condition these ped/bike counts were manually adjusted to reflect the anticipated increase in pedestrian/bicycle activity to result from the project (i.e., overcrossing connectivity and planned bicycle and pedestrian facilities in the proposed project). Additionally, future forecasts included the completion of the Prado Creek Bridge project and related Higuera Street / Prado Road intersection improvements, as well as the planned extension of Prado Road east to Broad Street. Future (Year 2050) forecasts for the AM and PM peak hours for the 2-lane overcrossing are shown in Figure 3. I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 7 Page 194 of 1059 7•51 1/ , i F �,. f FIGURE 3: FUTURE (YEAR 2050) INTERSECTION VOLUMES - 2-LANE OVERCROSSING I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 8 Page 195 of 1059 VOLUME C SON To ensure consistency with the prior Traffic Operations Analysis Report (TOAR) completed in 2019, and the updated TOAR completed in 2023, the volume forecasts at Madonna Road, Prado Road, and Los Osos Valley Road were compared between the prior reports and the forecasting completed for this study. The 2023 report utilized the same base data as the 2019 report and applied a 5% growth factor to the forecasts to represent an adjusted forecast year of 2045 compared to the 2040 forecast used in the original TOAR. For the 2019 TOAR and 2023 TOAR update, traffic counts from 2014 were used to establish existing conditions. Table 2 summarizes the following data: • The 2014 counts from the TOAR • The 2025 counts collected for this study • The 2025 forecast from the TOAR Update • The 2045 No Project (i.e., no Prado Road OC) forecast from the TOAR update • The 2050 No Project forecast prepared by this study • The 2045 Project (i.e., 4-lane Prado Road OC) forecast from the TOAR update • The 2050 Project (i.e., 4-lane and 2-lane Prado Road OC) forecasts prepared by this study Several data trends can be discerned from this data comparison. First, the 2025 Count data collected generally aligns with the previously forecasted 2025 data during both the AM and PM peak periods. Second, the updated 2050 No Project forecasts are lower in most cases than the previous 2045 forecasts. This is generally due to changes in the City General Plan land use data used in the newer forecasts. This same trend continues in the Project forecast volumes, except at the Prado Road interchange, where the updated forecasts are higher than those shown in the 2023 TOAR forecast. Finally, when comparing the 4-lane overcrossing project forecasts with the 2-lane overcrossing project forecasts, the table shows that most travel demands shift by 10% or less. The net result of this data comparison shows that results from this VE study are in alignment with the adopted TOAR. If re-evaluation of facilities beyond the Prado Road interchange were to be conducted, they would show similar or improved operational performance when compared with the adopted TOAR. The data also shows that changes in City planning has resulted in lower potential vehicle demand growth at the subject interchanges over time when compared with prior studies. VEHICLE MILES TRAVELLED (VMT) IMPLIC ONS The findings of volume comparison suggest a neutral effect on VMT. The close alignment between the updated travel forecasts with the adopted TOAR combined with the lower or de-minimis volume differences between the 4-lane and the 2-lane cross section supports this finding. To repeat, if re- evaluation of facilities beyond the Prado Road interchange were to be conducted, they would show similar or improved operational performance (i.e., lower future volumes and therefore lower VMT) when compared with the adopted TOAR. Recently revised land use projections by the City have resulted in lower potential vehicle demand growth (i.e., VMT) within the US 101/Prado Interchange study area when compared with prior studies including the adopted TOAR. 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S 0 0 0 0 O O j j j j j j 0 0 0 0 a a a a a a m m m c c c c m m w y w m m m m Z Z Z Z Z Z Z z Z ql (/1 K G G K Z Z 0 O 0 O 0 O Z Z y M Z Z Z Z Z Z ei ei ey ey 0 0 0 0 O O O O O O c,'o c,� p O p p 0 0 0 0 0 0�� a a a a a a vi vh vh s y d a m o� a>> y y 0 J 0 J 0 J 0 J 0 J 0 J> y y y (n FREEWAY AN YSIS — LEISCH METHOD The Leisch method is a freeway weaving analysis procedure developed by Jack E. Leisch for evaluating the operational performance of freeway segments where entering and exiting traffic streams must cross paths over a limited distance, such as between successive on- and off -ramps, and evaluating whether the available weaving length, number of lanes, traffic volumes, and distribution of weaving and non -weaving movements can accommodate the expected demand. In a freeway analysis, forecast or observed traffic volumes are assigned to each movement through the weaving section, then compared against the operating thresholds or service -volume relationships established by the Leisch procedure to estimate whether the segment is likely to operate acceptably or experience speed reductions, turbulence, or congestion. The results are used as a planning -level screening tool to flag ramp -spacing or lane -changing constraints and to determine whether improvements such as auxiliary lanes, revised ramp configurations, increased weaving distance, or more detailed operational analysis may be needed. For purposes of this analysis, the Leisch method will be performed using Excel -based tools to evaluate freeway weaving operations based on traffic volumes, lane configurations, and weaving -section geometry. The Leisch method determines the LOS of the overall weaving section by comparing the calculated service volume (SV), expressed in passenger cars per hour per lane (pcphpl), to the allowable service -volume thresholds for the number of basic freeway lanes (Nb). In practice, the analysis first converts demand volumes to passenger -car flow rates, identifies the applicable weaving configuration, and uses the Leisch nomograph or Excel implementation to determine the resulting SV for the section. That SV is then compared to the LOS thresholds shown in Table 3. The Leisch procedure also recognizes that weaving and non -weaving traffic may operate at different levels of service; in those cases, supplemental speed calibration is used to reconcile the overall section LOS with the weaving -movement LOS. TABLE 3: LEISCH METHOD LOS LEVEL OF SERVICE (LOS) MAXIMUM SERVICE VOLUME (PCPHPL) NB=2 NB=3 NB=4 A 750 800 850 B 1000 1100 1200 C 1250 1350 1450 D 1550 1600 1650 E 1900 1900 1900 F >1900 >1900 >1900 I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 11 Page 198 of 1059 The following section describes the intersection and freeway operations for Future Year (2050). The delay, LOS and queue results for SYNCHRO (Section 1) and VISSIM () as well as the Leisch method graph results () can be found in the Appendix. LEVEL OF SERVICE (LOS) The analysis results for the intersection performance for the Future Year (2050) AM and PM peak hours are provided in Table 4. As shown, under No Build conditions, the Prado Road / US 101 NB / Elks Lane intersection is projected to operate at LOS F during the PM peak hour with significant delay (> 2 minutes). Under Build (GAD Design 2-Lane Overcrossing) conditions, all intersections under both time periods would operate at LOS C or better. When comparing results from SYNCHRO and VISSIM (microsimulation), they are generally similar between time periods, showing that even though the VISSIM models were not calibrated to existing conditions, the assumptions made for driver behavior are consistent with the output from SYNCHRO. T E 4: NO -BUILD FUT YEAR (2050) INT ON PERFORMANCE — DELAY AND LOS DELAY ^ (LOS) GAD DESIGN (2-LANE OC) INTERSECTION SOFTWARE B NO BUILD c AM PEAK PM PEAK AM PEAK PM PEAK DELAY LOS DELAY LOS PRADO RD / US SYNCHRO 23 (C) 130 (F) 17 B 19 B 101 NB RAMPS VISSIM 19 (C) 202 (F) 20 C 19 B PRADO RD / SYNCHRO - - 16 B 21 C ELKS LN VISSIM - - 14 B 26 C Note: A. Average delay in seconds per vehicle. Bold indicates the LOS exceeds the City's mobility standard. B. SYNCHRO is a deterministic model and VISSIM a microsimulation model. While the results may be similar, SYNCHRO does not consider downstream queue spillback, while VISSIM does. C. The Prado Rd / Elks Ln intersection does not exist in the No Build. Elks Ln intersects Prado Rd at the NB off -ramp. QUEING ANALYSIS The Future (2050) average and 95th percentile queue lengths for each intersection for the AM and PM peak hours are presented in Table 5 through Table S. Also shown are queue lengths from SYNCHRO and VISSIM, with VISSIM queues generally longer than queues from SYNCHRO. It should be noted (and described above), the SYNCHRO queue lengths are calculated using equations while VISSIM queue lengths are calculated from observed queue lengths. However, the results between SYNCHRO and VISSIM are consistent in identifying movements that could experience queues in the future. The following discussion is based on the results of the VISSIM analysis. I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 12 Page 199 of 1059 AVERAGE Q LENGTH As shown in the tables, average queue lengths (i.e., the queue experienced on average by a driver) are expected to be contained within the available storage and do not extend back to upstream intersections, except for the following: No Build Westbound at Prado Road / US 101 NB Ramps (PM peak) While the No Build westbound average queue does not extend to Higuera Street during the PM peak, it is within 100 feet of the intersection, meaning that at any given time during the PM peak queues are expected to extend from the US 101 NB ramps back to nearly Higuera Street. This is consistent with the high delay for this movement shown in Table 4. 95TH PERCENTILE Q LENGTH As shown in the tables, several 95t" percentile queue lengths are expected to exceed available storage or extend back to upstream intersections during both the AM and PM peak hours, as described below: No Build Westbound at Prado Road / US 101 NB Ramps (PM peak) During the PM peak, under No Build conditions, westbound queues are projected to extend back beyond Higuera Street. GAD Design • Northbound right at Prado Road / US 101 NB Ramps (AM peak) • Westbound right at Prado Road / US 101 NB Ramps (PM peak) • Westbound through at Prado Road / US 101 NB Ramps (PM peak) • Westbound through at Prado Road / Elks Lane (PM peak) During the AM peak hour the northbound right -turn queue would exceed available storage (330 feet) but does not result in queues back onto the US 101 NB mainline. It should be noted that the 95tn percentile queue of 345 feet is less than one vehicle beyond the available storage, and would likely only queue into the taper The heavy westbound demand (1,600 to 1,700) during the PM peak hour results in westbound queues extending back from the US 101 NB Ramps (both in the right and through lanes) intersection to the Elks Lane intersection, and then back to the Higuera Street intersection. 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Z Z M > > W N Z V R N O w M W W W U O 0 Q m 0 C J a O Z z ta7 .Ni in 15 N L a� � U C II fo U 0 N L C _0 t CEn an O II _0 H fo w Q) _j U N II J (n a m ID N O N r a • } J Q Z Q U LL a H 0 Q 0 • w z a 2 U w H z 0 Q 0 0 Q a 0 z Q 0 Ln Z) Y 0 rn LO 0 0 0 N N (B w 0 z D O m O x F o O ul J Z L(1 O U) 00 n -q 1-1 O CO x O O N l0 a ~ OC LL O Z ..i x J O O OJ O H Z W a LU J J W OC a d M N LU N n Z Z W a Z n m Z o r O m Uf Ix O co 'i m O O J W a ~ �' ^ x W # oOG F 3 m -1 O CA c c Uf O IY a = o z a W J W M z W M O m ~ Ln O D+ H N M ♦Y � Q O W x Ln Ln J 1 M Q W a a W a o0c f o°c f x � U x U Ln LLO N 0 i i W 7 W F N Z V O O z J .. M V) W W Z W W F M 0 coJ C m a OZ aN Fz., �.. rn rs LO o vl- - 0 0 N N ca a_ c 0 u U N L Y C E fu Q) Y O a X N C Q) t Y O Y Y U fu C N Y X Q) ID L O N O :5 N rn c Q v N Ol • fu .�. U) } N J L Q +' Z 1A L Q Q) 0) v U X O LL Q) LL a a� O N T H ra 0 O Q N N 0 L 7 a) N 7 6 W O U Z C_ +� U fa Q = Q U G fa 0� J U W O m m � Z N Ln X Y 4-; Q o 0 cl� fu E O > 6 a C O U Z O II N Q o � J N Ln 7 II II � j J *k u _6 CONGES ON Visual inspection of the congestion provides additional context for the Build scenario operations. As shown in Figure 4 (AM) and Figure 5 (PM), some localized congestion is expected on the US 101 northbound off -ramp during the AM peak and along Prado Road during the PM peak. However, the slowing and queuing remain generally contained within the study area and do not extend far enough to affect upstream facilities, including the freeway mainline or adjacent intersections. In contrast, the No Build PM condition (Figure 6) shows substantially more queuing, with congestion extending east from the US 101 northbound ramps along Prado Road to beyond Higuera Street. This comparison indicates that the Build scenario would reduce the extent and severity of queuing relative to the No Build condition. FIGURE 4: GAD DES GN (2-LANE OVERCIHOS NG) AM CONGES ON - Free Flow - Some Slowing Increased Slowing - Some Stop -and -Go I- Significant Stop -and -Go - Constant Stop -and -Go ® undefined I r� Oak I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 205 of 1059 STI p eTAM d FIGURE 5: GAD DE GN (2-LANE OVE NG) PM CONGE ON FIGURE 6: NO BUILD PM CONGE ON I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 206 of 1059 FREEWAY ANALY S SI The Leisch method results show that in Year 2050 the US 101 NB weave between Prado Road on - ramp and Madonna Road off -ramp would operate at LOS C in the AM peak and LOS D in the PM peak, showing that the proposed aux lane from Prado Road on -ramp to Madonna Road off -ramp would operate acceptably. Overall, the GAD Design (2-Lane Overcrossing) provides a clear operational benefit compared to the No Build condition by improving intersection operations, reducing delay, and better managing queues under future 2050 AM and PM peak hour conditions. The analysis shows that the Prado Road / US 101 northbound ramps / Elks Lane intersection in No Build is projected to operate at LOS F during the PM peak hour with significant delay greater than two minutes, while the Build (GAD Design 2- Lane Overcrossing) condition operates at LOS C or better at all study intersections in both peak periods. The GAD Design (2-Lane Overcrossing) also provides benefits by containing congestion and reducing the extent of queuing relative to the No Build condition. While some localized queues are expected in the Build (GAD Design 2-Lane Overcrossing) scenario, including on the US 101 northbound off - ramp in the AM peak and along Prado Road in the PM peak, the congestion generally remains within the study area and does not extend far enough to affect upstream facilities such as the freeway mainline. By comparison, the No Build PM condition shows extensive queuing along Prado Road from the US 101 northbound ramps toward and beyond Higuera Street. This indicates that the GAD design (2-Lane Overcrossing) improves overall corridor operations, provides better queue management, and supports the planned Prado Road extension and multimodal connectivity improvements. I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 20 Page 207 of 1059 C S Section 1: SYNCHRO Results Section 2: VISSIM Results Section 3: Leisch Method Results I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 208 of 1059 SECTION 1: SYNCHRO RESULTS I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 209 of 1059 NO BUILD A PEA HOUM I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 210 of 1059 HCM 7th AWSC 3: US 101 NB Off/Elks Lane & Prado Rd 0 No Build AM Intersection Intersection Delay, s/veh 22.8 Intersection LOS C Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations 1� r Traffic Vol, veh/h 0 0 0 0 565 15 0 30 310 55 0 15 Future Vol, veh/h 0 0 0 0 565 15 0 30 310 55 0 15 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Heavy Vehicles, % 2 2 2 4 10 10 4 5 5 20 4 20 Mvmt Flow 0 0 0 0 565 15 0 30 310 55 0 15 Number of Lanes 0 0 0 0 1 0 0 1 0 1 0 1 Approach WB NB SIB Opposing Approach SIB NB Opposing Lanes 0 2 1 Conflicting Approach Left NB WB Conflicting Lanes Left 1 0 1 Conflicting Approach Right SIB WB Conflicting Lanes Right 2 1 0 HCM Control Delay, s/veh 29.6 13.7 10.9 HCM LOS D B B Lane NBLn1 WBLn1 SBLn1 SBLn2 Vol Left, % 0% 0% 100% 0% Vol Thru, % 9% 97% 0% 0% Vol Right, % 91 % 3% 0% 100% Sign Control Stop Stop Stop Stop Traffic Vol by Lane 340 580 55 15 LT Vol 0 0 55 0 Through Vol 30 565 0 0 RT Vol 310 15 0 15 Lane Flow Rate 340 580 55 15 Geometry Grp 4a 2 5 5 Degree of Util (X) 0.503 0.841 0.115 0.026 Departure Headway (Hd) 5.323 5.219 7.546 6.32 Convergence, Y/N Yes Yes Yes Yes Cap 677 696 474 565 Service Time 3.366 3.248 5.306 4.079 HCM Lane V/C Ratio 0.502 0.833 0.116 0.027 HCM Control Delay, s/veh 13.7 29.6 11.3 9.2 HCM Lane LOS B D B A HCM 95th-tile Q 2.8 9.4 0.4 0.1 City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1 Page 211 of 1059 NO BUILD P PEAK HOUR I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 212 of 1059 HCM 7th AWSC 3: US 101 NB Off/Elks Lane & Prado Rd 0 No Build PM Intersection Intersection Delay, s/veh 130.2 Intersection LOS F Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations 1� r Traffic Vol, veh/h 0 0 0 0 980 30 0 10 125 45 0 25 Future Vol, veh/h 0 0 0 0 980 30 0 10 125 45 0 25 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Heavy Vehicles, % 2 2 2 4 5 5 2 5 5 10 4 10 Mvmt Flow 0 0 0 0 980 30 0 10 125 45 0 25 Number of Lanes 0 0 0 0 1 0 0 1 0 1 0 1 Approach WB NB SIB Opposing Approach SIB NB Opposing Lanes 0 2 1 Conflicting Approach Left NB WB Conflicting Lanes Left 1 0 1 Conflicting Approach Right SIB WB Conflicting Lanes Right 2 1 0 HCM Control Delay, s/veh 154.4 10.9 11 HCM LOS F B B Lane NBLn1 WBLn1 SBLn1 SBLn2 Vol Left, % 0% 0% 100% 0% Vol Thru, % 7% 97% 0% 0% Vol Right, % 93% 3% 0% 100% Sign Control Stop Stop Stop Stop Traffic Vol by Lane 135 1010 45 25 LT Vol 0 0 45 0 Through Vol 10 980 0 0 RT Vol 125 30 0 25 Lane Flow Rate 135 1010 45 25 Geometry Grp 4a 2 5 5 Degree of Util (X) 0.209 1.286 0.091 0.042 Departure Headway (Hd) 6.252 4.584 8.048 6.814 Convergence, Y/N Yes Yes Yes Yes Cap 578 798 448 529 Service Time 4.252 2.603 5.748 4.514 HCM Lane V/C Ratio 0.234 1.266 0.1 0.047 HCM Control Delay, s/veh 10.9 154.4 11.6 9.8 HCM Lane LOS B F B A HCM 95th-tile Q 0.8 37.9 0.3 0.1 City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1 Page 213 of 1059 GAD DESIGN A PEA HOUR I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 214 of 1059 HCM 7th Signalized Intersection Summary 3: US 101 NB Off/US 101 NB On & Prado Rd 01 GAD AM Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations + t r r* Traffic Volume (veh/h) 100 950 0 0 420 350 240 0 300 0 Future Volume (veh/h) 100 950 0 0 420 350 240 0 300 0 0 0 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 1.00 1.00 0.95 1.00 1.00 Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No - Adj Sat Flow, veh/h/In 1841 1841 0 0 1841 1841 1841 0 1841 Adj Flow Rate, vehlh 100 950 0 0 420 350 240 0 300 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 0 0 4 4 4 0 4 Cap, veh/h 143 1098 0 0 792 637 411 0 366 Arrive On Green 0.08 0.60 0.00 0.00 0.43 0.43 0.23 0.00 0.23 Sat Flow, veh/h 1753 1841 0 0 1841 1480 1753 0 1560 Grp Volume(v), veh/h 100 950 0 0 420 350 240 0 300 Grp Sat Flow(s),veh/h/In 1753 1841 0 0 1841 1480 1753 0 1560 Q Serve(g_s), s 3.3 25.5 0.0 0.0 10.0 10.4 7.2 0.0 10.8 Cycle Q Clear(g_c), s 3.3 25.5 0.0 0.0 10.0 10.4 7.2 0.0 10.8 Prop In Lane 1.00 0.00 0.00 1.00 1.00 1.00 Lane Grp Cap(c), veh/h 143 1098 0 0 792 637 411 0 366 V/C Ratio(X) 0.70 0.87 0.00 0.00 0.53 0.55 0.58 0.00 0.82 Avail Cap(c_a), veh/h 592 1555 0 0 1555 1250 592 0 527 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 0.00 0.00 1.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 26.5 10.0 0.0 0.0 12.4 12.6 20.1 0.0 21.5 Incr Delay (d2), s/veh 6.0 3.9 0.0 0.0 0.6 0.7 1.3 0.0 6.7 Initial Q Delay(d3), slveh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/In 1.5 8.1 0.0 0.0 3.5 3.0 2.7 0.0 4.0 Unsig. Movement Delay, slveh LnGrp Delay(d), s/veh 32.5 13.8 0.0 0.0 13.0 13.3 21.4 0.0 28.2 LnGrp LOS C B B B C C Approach Vol, veh/h 1050 770 540 Approach Delay, s/veh 15.6 13.1 25.2 Approach LOS B B C Timer - Assigned Phs 2 5 6 8 Phs Duration (G+Y+Rc), s 40.3 9.8 30.5 18.9 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 50.0 20.0 50.0 20.0 Max Q Clear Time (g_c+ll ), s 27.5 5.3 12.4 12.8 Green Ext Time (p-c), s 7.8 0.2 4.3 1.1 Intersection S HCM 7th Control Delay, s/veh 17.0 HCM 7th LOS B City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1 Page 215 of 1059 Queues 3: US 101 NB Off/US 101 NB On & Prado Rd 01 GAD AM Lane Group EBL EBT WBT WBR NBL NBR Lane Group Flow (vph) 100 950 420 350 240 300 v/c Ratio 0.43 0.90 0.56 0.44 0.49 0.69 Control Delay (s/veh) 36.3 25.7 20.9 3.9 28.3 35.9 Queue Delay 0.0 0.0 0.0 0.0 0.0 0.0 Total Delay (s/veh) 36.3 25.7 20.9 3.9 28.3 35.9 Queue Length 50th (ft) 44 341 152 0 95 127 Queue Length 95th (ft) 95 544 259 51 188 #281 Internal Link Dist (ft) 786 602 Turn Bay Length (ft) 130 330 Base Capacity (vph) 487 1794 1283 1105 487 436 Starvation Cap Reductn 0 0 0 0 0 0 Spillback Cap Reductn 0 0 0 0 0 0 Storage Cap Reductn 0 0 0 0 0 0 Reduced v/c Ratio 0.21 0.53 0.33 0.32 0.49 0.69 Intersection Summary # 95th percentile volume exceeds capacity, queue may be longer. Queue shown is maximum after two cycles. City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1 Page 216 of 1059 HCM 7th Signalized Intersection Summary 6: Elks Lane & Prado Rd 01 AM --I. t \*. IIGAD i Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations ti +T T 1� Traffic Volume (veh/h) 40 1170 40 20 730 20 10 5 5 40 20 30 Future Volume (veh/h) 40 1170 40 20 730 20 10 5 5 40 20 30 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 0 0 0 Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 0.95 1.00 0.95 1.00 0.96 1.00 0.97 Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No No Adj Sat Flow, veh/h/In 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 Adj Flow Rate, vehlh 40 1170 40 20 730 20 10 5 5 40 20 30 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 4 4 4 4 4 4 4 4 4 4 Cap, veh/h 82 1586 54 49 1532 42 27 137 137 82 128 193 Arrive On Green 0.05 0.46 0.46 0.03 0.44 0.44 0.02 0.17 0.17 0.05 0.20 0.20 Sat Flow, veh/h 1753 3443 118 1753 3471 95 1753 828 828 1753 651 977 Grp Volume(v), veh/h 40 594 616 20 368 382 10 0 10 40 0 50 Grp Sat Flow(s),veh/h/In 1753 1749 1812 1753 1749 1818 1753 0 1655 1753 0 1629 Q Serve(g_s), s 1.5 18.5 18.6 0.8 9.9 9.9 0.4 0.0 0.3 1.5 0.0 1.7 Cycle Q Clear(g_c), s 1.5 18.5 18.6 0.8 9.9 9.9 0.4 0.0 0.3 1.5 0.0 1.7 Prop In Lane 1.00 0.06 1.00 0.05 1.00 0.50 1.00 0.60 Lane Grp Cap(c), veh/h 82 806 835 49 772 802 27 0 274 82 0 321 V/C Ratio(X) 0.48 0.74 0.74 0.41 0.48 0.48 0.38 0.00 0.04 0.48 0.00 0.16 Avail Cap(c_a), veh/h 262 1569 1626 262 1569 1631 262 0 619 262 0 609 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 31.1 14.7 14.7 32.0 13.2 13.2 32.6 0.0 23.4 31.1 0.0 22.2 Incr Delay (d2), s/veh 4.4 1.3 1.3 5.4 0.5 0.4 8.5 0.0 0.1 4.4 0.0 0.2 Initial Q Delay(d3), slveh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/In 0.7 6.5 6.8 0.4 3.5 3.6 0.2 0.0 0.1 0.7 0.0 0.7 Unsig. Movement Delay, slveh LnGrp Delay(d), s/veh 35.4 16.1 16.0 37.4 13.7 13.6 41.1 0.0 23.5 35.4 0.0 22.5 LnGrp LOS D B B D B B D C D C Approach Vol, veh/h 1250 770 20 90 Approach Delay, s/veh 16.7 14.3 32.3 28.2 Approach LOS B B C C Timer - Assigned Phs 1 2 3 4 5 6 7 8 Phs Duration (G+Y+Rc), s 6.9 35.8 6.0 18.2 8.1 34.5 8.1 16.1 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 10.0 60.0 10.0 25.0 10.0 60.0 10.0 25.0 Max Q Clear Time (g_c+ll ), s 2.8 20.6 2.4 3.7 3.5 11.9 3.5 2.3 Green Ext Time (p-c), s 0.0 10.2 0.0 0.2 0.0 5.2 0.0 0.0 Intersection S HCM 7th Control Delay, s/veh HCM 7th LOS 16.4 B City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2 Page 217 of 1059 Queues 6: Elks Lane & Prado Rd 01 GAD AM Lane Group EBL EBT WBL WBT NBL NBT SBL SBT Lane Group Flow (vph) 40 1210 20 750 10 10 40 50 v/c Ratio 0.15 0.49 0.08 0.30 0.04 0.04 0.15 0.17 Control Delay (s/veh) 30.6 9.4 32.0 8.1 32.9 32.5 30.6 19.5 Queue Delay 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 Total Delay (s/veh) 30.6 9.4 32.0 8.1 32.9 32.5 30.6 19.5 Queue Length 50th (ft) 8 77 4 39 2 2 8 4 Queue Length 95th (ft) 57 356 36 196 23 23 57 48 Internal Link Dist (ft) 602 903 272 534 Turn Bay Length (ft) 240 190 100 100 Base Capacity (vph) 374 3143 374 3148 374 892 374 888 Starvation Cap Reductn 0 513 0 0 0 0 0 0 Spillback Cap Reductn 0 0 0 0 0 0 0 0 Storage Cap Reductn 0 0 0 0 0 0 0 0 Reduced v/c Ratio 0.11 0.46 0.05 0.24 0.03 0.01 0.11 0.06 Intersection Summary City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2 Page 218 of 1059 GAD DESIGN P PEAK HOUR I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 219 of 1059 HCM 7th Signalized Intersection Summary 3: US 101 NB Off/US 101 NB On & Prado Rd 01 GAD PM Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL Lane Configurations + t r r* Traffic Volume (veh/h) 100 600 0 0 910 780 180 0 150 0 Future Volume (veh/h) 100 600 0 0 910 780 180 0 150 0 0 0 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 1.00 1.00 0.96 1.00 1.00 - Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No - Adj Sat Flow, veh/h/In 1841 1841 0 0 1841 1841 1841 0 1841 Adj Flow Rate, vehlh 100 600 0 0 910 780 180 0 150 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 0 0 4 4 4 0 4 Fr Cap, veh/h 130 1347 0 0 1087 882 237 0 211 Arrive On Green 0.07 0.73 0.00 0.00 0.59 0.59 0.14 0.00 0.14 Sat Flow, veh/h 1753 1841 0 0 1841 1493 1753 0 1560 Grp Volume(v), veh/h 100 600 0 0 910 780 180 0 150 Grp Sat Flow(s),veh/h/In 1753 1841 0 0 1841 1493 1753 0 1560 Q Serve(g_s), s 4.2 9.7 0.0 0.0 30.0 33.6 7.4 0.0 6.9 Cycle Q Clear(g_c), s 4.2 9.7 0.0 0.0 30.0 33.6 7.4 0.0 6.9 Prop In Lane 1.00 0.00 0.00 1.00 1.00 1.00 Lane Grp Cap(c), veh/h 130 1347 0 0 1087 882 237 0 211 V/C Ratio(X) 0.77 0.45 0.00 0.00 0.84 0.88 0.76 0.00 0.71 Avail Cap(c_a), veh/h 467 1347 0 0 1226 995 467 0 416 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 0.00 0.00 1.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 34.1 4.0 0.0 0.0 12.4 13.2 31.3 0.0 31.1 Incr Delay (d2), s/veh 9.0 0.2 0.0 0.0 4.8 8.8 5.0 0.0 4.4 Initial Q Delay(d3), slveh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/In 2.0 2.3 0.0 0.0 11.2 11.0 3.2 0.0 2.7 Unsig. Movement Delay, slveh LnGrp Delay(d), s/veh 43.1 4.2 0.0 0.0 17.2 22.0 36.2 0.0 35.5 LnGrp LOS D A B C D D Approach Vol, veh/h 700 1690 330 Approach Delay, s/veh 9.8 19.4 35.9 Approach LOS A B D Timer - Assigned Phs 2 5 6 8 Phs Duration (G+Y+Rc), s 59.9 10.6 49.3 15.1 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 50.0 20.0 50.0 20.0 Max Q Clear Time (g_c+ll ), s 11.7 6.2 35.6 9.4 Green Ext Time (p-c), s 4.4 0.2 8.7 0.7 Intersection S HCM 7th Control Delay, s/veh 18.9 HCM 7th LOS B City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2 Page 220 of 1059 Queues 3: US 101 NB Off/US 101 NB On & Prado Rd 01 GAD PM ■-- Lane Group EBL EBT WBT WBR NBL NBR Lane Group Flow (vph) 100 600 910 780 180 150 v/c Ratio 0.49 0.45 0.86 0.72 0.65 0.60 Control Delay (s/veh) 46.3 6.7 29.1 8.0 46.9 46.1 Queue Delay 0.0 0.0 1.0 0.0 0.0 0.0 Total Delay (s/veh) 46.3 6.7 30.1 8.0 46.9 46.1 Queue Length 50th (ft) 56 118 443 45 100 83 Queue Length 95th (ft) 113 223 #871 238 179 154 Internal Link Dist (ft) 786 602 Turn Bay Length (ft) 130 330 Base Capacity (vph) 401 1552 1058 1085 401 358 Starvation Cap Reductn 0 0 36 0 0 0 Spillback Cap Reductn 0 0 0 0 0 0 Storage Cap Reductn 0 0 0 0 0 0 Reduced v/c Ratio 0.25 0.39 0.89 0.72 0.45 0.42 Intersection Summary # 95th percentile volume exceeds capacity, queue may be longer. Queue shown is maximum after two cycles. City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1 Page 221 of 1059 HCM 7th Signalized Intersection Summary 6: Elks Lane & Prado Rd 01 PM --I. t IGAD i Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations tT ti T 1� Traffic Volume (veh/h) 50 690 10 10 1600 20 30 20 20 50 10 60 Future Volume (veh/h) 50 690 10 10 1600 20 30 20 20 50 10 60 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 0 0 0 Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 0.96 1.00 0.96 1.00 0.96 1.00 0.96 Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No No Adj Sat Flow, veh/h/In 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 Adj Flow Rate, vehlh 50 690 10 10 1600 20 30 20 20 50 10 60 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 4 4 4 4 4 4 4 4 4 4 Cap, veh/h 82 2019 29 26 1910 24 61 123 123 82 36 214 Arrive On Green 0.05 0.57 0.57 0.01 0.54 0.54 0.03 0.15 0.15 0.05 0.16 0.16 Sat Flow, veh/h 1753 3526 51 1753 3535 44 1753 826 826 1753 220 1322 Grp Volume(v), veh/h 50 342 358 10 791 829 30 0 40 50 0 70 Grp Sat Flow(s),veh/h/In 1753 1749 1829 1753 1749 1830 1753 0 1651 1753 0 1543 Q Serve(g_s), s 2.6 9.6 9.6 0.5 35.1 35.2 1.6 0.0 2.0 2.6 0.0 3.7 Cycle Q Clear(g_c), s 2.6 9.6 9.6 0.5 35.1 35.2 1.6 0.0 2.0 2.6 0.0 3.7 Prop In Lane 1.00 0.03 1.00 0.02 1.00 0.50 1.00 0.86 Lane Grp Cap(c), veh/h 82 1001 1047 26 945 989 61 0 247 82 0 249 V/C Ratio(X) 0.61 0.34 0.34 0.39 0.84 0.84 0.49 0.00 0.16 0.61 0.00 0.28 Avail Cap(c_a), veh/h 190 1135 1187 190 1135 1188 190 0 446 190 0 417 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 43.2 10.5 10.5 45.1 17.8 17.9 43.8 0.0 34.3 43.2 0.0 34.0 Incr Delay (d2), s/veh 7.0 0.2 0.2 9.3 4.8 4.7 6.0 0.0 0.3 7.0 0.0 0.6 Initial Q Delay(d3), slveh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/In 1.3 3.4 3.6 0.3 13.8 14.5 0.8 0.0 0.8 1.3 0.0 1.4 Unsig. Movement Delay, slveh LnGrp Delay(d), s/veh 50.3 10.7 10.7 54.4 22.6 22.5 49.8 0.0 34.6 50.3 0.0 34.7 LnGrp LOS D B B D C C D C D C Approach Vol, veh/h 750 1630 70 120 Approach Delay, s/veh 13.3 22.8 41.1 41.2 Approach LOS B C D D Timer - Assigned Phs 1 2 3 4 5 6 7 8 Phs Duration (G+Y+Rc), s 6.4 57.9 8.2 19.9 9.3 55.0 9.3 18.8 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 10.0 60.0 10.0 25.0 10.0 60.0 10.0 25.0 Max Q Clear Time (g_c+ll ), s 2.5 11.6 3.6 5.7 4.6 37.2 4.6 4.0 Green Ext Time (p-c), s 0.0 4.8 0.0 0.3 0.0 12.7 0.0 0.1 Intersection S HCM 7th Control Delay, s/veh HCM 7th LOS 21.4 C City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 4 Page 222 of 1059 Queues 6: Elks Lane & Prado Rd 01 GAD PM -11 --IN. i Lane Group EBL EBT WBL WBT NBL NBT SBL SBT Lane Group Flow (vph) 50 700 10 1620 30 40 50 70 v/c Ratio 0.30 0.27 0.07 0.71 0.20 0.24 0.30 0.32 Control Delay (s/veh) 50.6 7.2 49.6 18.5 49.5 49.3 50.6 19.9 Queue Delay 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total Delay (s/veh) 50.6 7.2 49.6 18.5 49.5 49.3 50.6 19.9 Queue Length 50th (ft) 33 83 7 444 20 27 33 7 Queue Length 95th (ft) 75 180 26 633 52 63 75 51 Internal Link Dist (ft) 602 903 272 534 Turn Bay Length (ft) 240 190 100 100 Base Capacity (vph) 216 2585 216 2378 216 516 216 520 Starvation Cap Reductn 0 0 0 0 0 0 0 0 Spillback Cap Reductn 0 0 0 0 0 0 0 0 Storage Cap Reductn 0 0 0 0 0 0 0 0 Reduced v/c Ratio 0.23 0.27 0.05 0.68 0.14 0.08 0.23 0.13 Intersection Summary City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 3 Page 223 of 1059 SECTION 2: VISSIM RESULTS I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 224 of 1059 NO BUILD A PEA HOUM I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 225 of 1059 City of SLO - US101 Prado Road Interchange No Build AM ,TABLE: AVERAGE DEL" Demand Served Average Intersection Approach Movement Volume Volume % Served GEH Delay (s) LOS Left - - Through 30 34 113% 0.7 8 A NB Right 310 308 99% 0.1 4 A U-Turn - - Total 340 342 1010/0 0.1 4 A US 101 Ramps / Prado Rd / Elks Ln Left 55 54 98% 0.1 6 A Through - - SB Right 15 14 93% 0.3 3 A U-Turn - - Total 70 68 97% 0.2 5 A Left - Through EB Right U-Turn Total - - 0 Left - - Through 565 563 100% 0.1 30 D WB Right 15 15 100% 0.0 22 C U-Turn - - Total 580 578 1000/0 0.1 30 D Total 990 988 1000/0 0.1 19 C DKS Associates Page 226/04059 City of SLO - US101 Prado Road Interchange No Build AM 40 (120) 20 (60) L+ L 225 (475) r DKS Associates Page 227 of '026 NO BUILD P PEAK HOUR US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 228 of 1059 City of SLO - US101 Prado Road Interchange No Build PM Demand Served Average Intersection proach Movement Volume Volume % Served GEH Delay (s) LOS Left - - Through 10 11 110% 0.3 7 A NB Right 125 123 98% 0.2 2 A U-Turn - - Total 135 134 99% 0.1 2 A Left 45 44 98% 0.1 6 A Through - - SB Right 25 23 92% 0.4 4 A U-Turn - - Total 70 67 960/a 0.4 5 A US 101 Ramps / Left Prado Rd / Elks Ln Throug EB Right U-Turn Total 0 Left - - Through 980 600 61% 13.5 267 F WB Right 30 19 63% 2.2 260 F U-Turn - - Total 1010 619 61% 13.7 267 F Total 1215 820 67% 12.4 202 F DKS Associates Page 229/04059 City of SLO - US101 Prado Road Interchange No Build PM 20 (60) L+ 1: US 101 Ramps / Prado Rd / 1545(1690) Elks Ln +, r r 10 (60) DKS Associates Page 230 of WW026 GAD DESIGN A PEA HOUR I® US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 231 of 1059 City of SLO - US101 Prado Road Interchange GED Design AM ,TABLE: AVERAGE DEL" Demand Served Average Intersection Approach Movement Volume Volume % Served GEH Delay (s) LOS Left 240 236 98% 0.3 35 C Through - - NB Right 300 303 101% 0.2 36 D U-Turn - - Total 540 539 1000/0 0.0 35 D US 101 Ramps / Prado Rd Left - Through - SB Right - U-Turn Total - - 0 Left 100 98 98% 0.2 42 D Through 950 947 100% 0.1 16 B EB Right - - U-Turn - - Total 1050 1045 100% 0.2 18 B Left - - Through 420 417 990/0 0.1 16 B WB Right 350 351 100% 0.1 10 A U-Turn - - Total 770 768 100% 0.1 13 B Total 2360 2352 100% 0.2 20 C Left 10 10 100% 0.0 51 D Through 5 5 100% 0.0 43 D NB Right 5 4 80% 0.5 39 D U-Turn - - Total 20 19 950/0 0.2 47 D Left 40 40 100% 0.0 46 D Through 20 20 100% 0.0 33 C SB Right 30 29 97% 0.2 9 A U-Turn - - Total 90 89 990/0 0.1 31 C Elks Ln / Prado Rd Left 40 37 93% 0.5 40 D Through 1170 1176 101% 0.2 11 B EB Right 40 39 98% 0.2 9 A U-Turn - - Total 1250 1252 1000/0 0.1 12 B Left 20 19 95% 0.2 42 D Through 730 729 100% 0.0 13 B WB Right 20 21 105% 0.2 9 A U-Turn - - Total 770 769 100% 0.0 14 B Total 2130 2129 100% 0.0 14 B DKS Associates Page 232/0 4®59 City of SLO - US101 Prado Road Interchange GAD Design AM L+ 75 (155) J t 135 (375) 390 (855) • . • • 160 (380) z r t F+ 125 (240) 175 (345) 25 (75) 35 (85) L4 30 (70) J t 185 (325) • . • • � 150 (310) Z r 20 (60) t r+ 10 (45) 10 (40) DKS Associates Page 233 of '026 GAD DESIGN P PEAK HOUR US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 234 of 1059 City of SLO - US101 Prado Road Interchange GAD Design PM ,TABLE: AVERAGE DEL" Demand Served Average Intersection proach Movement Volume Volume % Served GEH Delay (s) LOS Left 180 178 99% 0.1 36 D Through - - NB Right 150 152 101% 0.2 31 C U-Turn - - Total 330 330 100% 0.0 34 C Left Through SB Right U-Turn Total - - - - - 0 US 101 Ramps / Left 100 95 95% 0.5 36 D Prado Rd Through 600 603 101% 0.1 8 A EB Right - - U-Turn - - Total 700 698 1000/0 0.1 11 B Left - - Through 910 900 99% 0.3 17 B WB Right 780 787 101% 0.3 23 C U-Turn - - Total 1690 1687 1000/0 0.1 20 B Total 2720 2715 100010 0.1 19 B Left 30 28 93% 0.4 55 D Through 20 21 105% 0.2 43 D NB Right 20 18 90% 0.5 36 D U-Turn - - Total 70 67 96% 0.4 46 D Left 50 52 104% 0.3 50 D Through 10 11 110% 0.3 48 D SB Right 60 58 97% 0.3 17 B U-Turn - - Total 120 121 101010 0.1 34 C Elks Ln / Prado Rd Left 50 50 100% 0.0 59 E Through 690 694 101% 0.2 10 A EB Right 10 8 80% 0.7 7 A U-Turn - - Total 750 752 1000/0 0.1 13 B Left 10 8 80% 0.7 68 E Through 1600 1595 100% 0.1 30 C WB Right 20 20 100% 0.0 27 C U-Turn - - Total 1630 1623 1000/0 0.2 30 C Total 2570 2563 1000/0 0.1 26 C DKS Associates Page 235/04059 City of SLO - US101 Prado Road Interchange GAD Design PM L+ 65 (135) J t 455 (735) 135 (320) Ramps ' • 455 (740) z r t F+ 100 (200) 85 (180) 35 (90) 40 (95) L4 45 (105) J t 105 (220) • . • • 545 (945) Z r 10 (45) t r+ 25 (65) 30 (80) DKS Associates Page 236 of '026 SECTION 3: LEISCH METHOD RESULTS 0 US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 Page 237 of 1059 aj tio � 2 \ 2 2 = 2 � \ $ § \ / -a } \ r / E © / E E § \ \ / ) it o o G \ R « R - ® - e E \ 2 to L & } a)\ � / � � ] E { / E / § > > j ® R \ \ m 2 � � o 2 { ± u E > / ƒ m ) 6 ( k E / } > > $ J / § j ƒ t \ro > § § / % k \cu _ - to/ a M \cu Q c j & \ \ 0 k \ / / \ j ( % / ( w 3 2 2 / § ± > > z \ $ f u ƒ R = _ ~ U ( ) f . 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( m & & 2 y k % ƒ } \ / I 2 CL - W k \ a) a % # E > & « } \ z a j \ } on> f a f _ % \ to j = > u J w¥¥ w a 0 C) m D 0 00 q q _ D _ � aj tio $ _ \ j 2 = 2 cc m } M § ° o } ƒ \ § 0 E © E / E \ / C a. / ) it o o g $ ID\ - � - R w E \ 2 \ W \ & } ƒ m / ] ( { / Lu § / § > > \ R 7 m R c CR 2 z � § 2 \ CL / > } \ � o E a E / § > > m q j m \ ® $ D ƒ > en % / %in a) \ w _ © \ a \ \ Q c \ & \ \ \ k \ / / \ j ( u / ( D 3 2 2 / § ± > > z / q m c ƒ R = _ r-Ln ~ 2 ( ( Q = t _ L \ ) _ \ / m { , J $ ( 2 y k % ƒ } \ / I 2 - W 11 k \ b ■ % # E > } & « } \ z a j \ \ } tin > y 0 / / \ } ff a _ % \ I t m/\ & j m .b > J w ¥¥ w a 0 C) m D 0 CY) q q _ D _ � rn LO 0 0 0 Nt N N (B n rn LO 0 0 Nt N N (B n rn LO 0 0 N Nt N N (B n II II II II II I, I, I, II II I 117 -1 I I I �emvi I � I I 8 I I esz ssy� I 8 a3 I I I 8 e I rn LO 0 0 Nt N N (B rn LO 0 0 It Nt N N (B n C) LO C) 0 Lr) Nt C\j (D n rn LO 0 0 cO Nt N N (B n n consor Prado Road Transmission Main Options Analysis Date: April 20, 2026 Project: Prado Road Interchange To: Matt Horn, PE City of San Luis Obispo From: Nickolas Buonarati, EIT Consor Reviewed By: Adam Blair, PE Consor Re: Prado Road Transmission Main Options Analysis Introduction The City of San Luis Obispo (City) has retained Consor North America (Consor) to design a new partial interchange at US 101 and Prado Road (project, overpass), to allow for a new crossing over the US 101 (highway). Part of the project's scope includes upgrades to existing utilities located on Prado Road, including a 12-inch diameter cast iron water main (main). During design, Consor determined that the new overpass will impact an existing segment of this main that crosses the highway. This line is critical to maintaining the City's robustness, connecting the east and west sides of the city. Consor has identified four options that could provide additional connectivity to the east side of the highway near Prado Road. These four options are outlined below followed by a summary table of the considerations for each option. Option 1: Jack and Bore Under Highway Trenchless pipeline installation is commonly used where open -cut pipe installation will cause increased risks, traffic disruptions, or environmental impacts. Option 1 utilizes the jack -and -bore method to install the 12-inch diameter main beneath the highway, minimizing surface disturbance. This approach is a cost- effective solution for this location. Jack and bore trenchless methods involve excavating a launch pit and a smaller receiving pit, which are typically designed by the contractor. The launch pit will then be used to bore the alignment while jacking a 42-inch-diameter steel casing under the highway. An internal auger unit in the casing removes soils back to the launch pit for hauling and disposal. Once the casing is installed between the launch and receiving pits, the 12-inch diameter main can be installed within the casing, connected to the existing piping at either end, and the pits can be backfilled. Even though no surface impacts are anticipated, an encroachment permit will still need to be acquired from the California Department of Transportation (Caltrans), as work will still be happening within their right-of- way. D218721CA.00 • March 2026 • City of San Luis Obispo Page 247 of 1059 Prado Road Interchange • 1 As outlined below, Consor has evaluated two potential locations for this work. For both options, Consor currently estimates the construction at $1,150,000 (based on 2026 unit prices, including a 50% Contingency and not including the cost to obtain easements). Although Option 1B is a slightly longer crossing, the cost is assumed the same as Option 1 for this high-level estimation. Option 1A: El Mercado to Elks Lane Option 1 utilizes a corridor crossing of the highway at El Mercado Street. The launch pit is excavated at the end of El Mercado, on the west side of US-101. The casing is then bored beneath US-1011 towards the receiving pit excavated east of US-101, at Elks Lane (old). Error! Reference source not found. below illustrates this configuration. mum. 4Wa iI APPROXIMATE SIZE '1 AND LOCATION OF V LAUNCH PIT 1i- kiff Figure 1: El Mercado to Elks Lane (Old) APPROXIMATE SIZE AND LOCATION OF t RECEIVING PIT EXISTING 12" CI WATERLINE PROPOSED 12" DI WATERLINE PROPOSED 42" STEEL CASING D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 2 Page 248 of 1059 Option 1B: Elks Lane to Embassy Suites Parking Lot An alternative to Option 1A is to excavate a launch pit at the corner where Elks Lane (new) starts and bore west beneath US-101 to a receiving pit located within the Embassy Suites parking lot property, necessitating an easement. A potential permitting concern is that this alignment has a larger skew angle than the option outlined above, deviating from a preferred perpendicular crossing. Option 1B is shown in Figure 2 below. EXISTING 12" CI 11; c 1 WATERLINE PROPOSED 12" DI �1 WATERLINE ` w PROPOSED 42" STEEL CASING APPROXIMATE �.. SIZE AND — ; rY , ., - Elks Lane (new) -- LOCATION OF Y y, RECEIVING PIT ALTERNATIVES � ''• APPROXIMATE ', ■ " {� i SIZE AND Zr 1 LOCATION OF Q +� LAUNCH PIT a v 1 ` 1 � ?� 0 1 us-101 1 Figure 2: Elks Lane (new) to Embassy Suites Parking Lot Alternatively, if the city does not want to obtain an easement from the Embassy Suites, they could instead obtain two easements from the empty lots south of the Embassy Suites, with access to the receiving pit just south of the property line between these lots and the parking lot. Easement requirements are outlined in Table 1 and Figure 3 below. D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 3 Page 249 of 1059 Table 1: Easements for Option 1B 053-012-030 053-153-007 053-153-012 Ode - °'o e Easement Needed Parcel #: 007 APN: 053-153-007 Embassy Suites Parking Easement Empty Lot Easements Easement Needed Parcel #: 030 APN: 053-012-030 Figure 3: Easements needed for Option 1B Easement Neede Parcel #: 012 APN: 053-153-01 030 007 012 Embassy Suites D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 4 Page 250 of 1059 Option 2: Northern Extension of Calle Joaquin Main Option 2 creates east -west connectivity north of Prado Road by extending an existing watermain that currently dead -ends in the cul-de-sac at Calle Joaquin (See Figure 4 for location). From Calle Joaquin the new main would travel north, parallel to the southbound lane to the highway until it meets the existing line at the new Prado Road overpass. This option would be installed utilizing open -cut trenching for the approximate 3,000 LF of new 12-inch ductile iron pipe, with limited, if any, impact to the highway. This option requires utilizing both new and existing City easements with properties adjacent to Caltrans right- of-way on the east side of the highway. Easement needs are outlined in Table 2 and Figure 4 below. Table 2: Option 2 - Easement Needs Currently, Consor estimates this option to be $2,300,000.00 (2026 Unit prices, including a 50% Contingency and not including cost of obtaining easements). Below, Figure 4 shows the approximate path that this waterline extension would take, alongside the easements listed in Table 2 above. D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 5 Page 251 of 1059 Existing City Construction Easement Parcel #: 013 APN: 053-153-013 Existing City Construction Easement Parcel #: 014 APN: 053-153-014 Construction Easement Needed Parcel #: 007 APN: 053-152-007 Construction Easement Needed Parcel #: 008 APN: 053-152-008 Construction Easement Needed Parcel #: 006 APN: 053-152-006 Figure 4: Waterline Extension Alignment Option 3: Waterline Over New Overpass Option 3 replaces the existing main in Prado Road with a new alignment that crosses the highway via the new overpass. The new alignment places the 12-inch diameter main in the eastside overpass approach fills and then east to west over the highway in a 24-inch diameter steel casing within the bridge structure. At the western side of the highway, the main would extend to bridge support "Bent 3" where a 90-degree bend routes the new line down a support column and connects to the existing 12-inch diameter underground watermain. If attaching the waterline to the column if not desirable, an alternative alignment could route the main further to the west in overpass approach soils, but would result in significantly more new pipe length to connect back to the water main adjacent to the highway (not included in cost). Flexible expansion joints are used at 4 locations along the alignment to provide long-term resilience for the line at the unconstrained bridge joints. Consor estimates this option to be approximately $1,190,000.00 (2026 Unit prices and including a 50% Contingency). Figure 5 and Figure 6 below show the general location of the waterline in relation to the overpass. D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchan e • 6 Page 252 of 1059 Appro. OG 12" DIP Waterline (direct buried) 12" DIP Waterline (bridge) in 24' Casing y Lint 53 54 S 62'4546' E 55 6 Extend to Sta 59+00 I < To S. Hia.-o 77 �G Try 3 Typ Need flextend expansion joint at each end of each bridge. 1 " metal nolNial. Figure 5: East Side of Overpass IT DIP Waterline (direct buried) ' w 12" DIP Waterline (bridge) in 24" Casing CURVE DATA 7 „ !o a .35. Or 53' T-213.68 10' :4' :410' tJ 88 46-2500 a' Way L-41366' - E1ev 149.59 \ Bent 3 0 �67500' n ES 50. 75 0 T1p 47 4a r 10&0 Need flextend expansion joint at each end of each bridge. End at Sta 49+00 PLAN must verify all T4-0-p 1i7e 6 before Figure 6: West Side of Overpass 0 To S. Maul A D218721CA.00 e April 2026 e City of San Luis Obispo Prado Road Interchange e 7 Page 253 of 1059 Option 4: Casing of 12-inch line in Prado Option 4 replaces the existing water main along Prado Road with a new section of 12-inch ductile iron pipe installed within a steel casing beneath the proposed overpass island. The existing 12-inch diameter ductile iron highway crossing at Prado Road is housed within a 24-inch casing. The encased section extends east of the highway and terminates at a point approximately midway through the planned overpass island. Under Option 4, a new 24-inch casing is installed over the new 12-inch ductile iron pipe and extended to tie into the existing casing. This approach provides continuous encasement of the water main beneath the entirety of the new overpass island. Consor estimates this option to be approximately $75,000.00 (2026 Unit prices and including a 50% Contingency. Cost assumes work is performed concurrent with other water utility improvements on Prado). Figure 7 below show the general location of the waterline in relation to the overpass. o o �7__%_+. 4. — { fio —REMOVE EXIST SEWS ' { + (SEE CITY OF SLO Y'LALIGNMENT WALL. LIMITS 6050) • VERPASS • APPROX 30 FTND ENCASEMENT TO EXTEND B FTCH DIAMETER • BEYOND MSETILE IRON PIPE _ R(W ABAN EXIST 8" WA WALL iOVERPASS WCITY OF SLO STD DISLAND) ATION BFV • APPROX ENO OF- • EXIST 12 INCH LINE - ++ _IC IN 24-INCH STEEL ,\ + XX XX X XXX X X XS X X X X X K X;X K X X K XX ENCASEMENT UNDER HIGHWAY PRADO ROAD ........ .....� •............... — .- -. — . -- fohi I} EXISNCH 121LE DUCTIT LINE CAP OR CONC PLUG SEE ( CITY OF SLO STD DET 6050)— ENCASEDIN 24-INCH DIAMETER CASING Figure 7: Pipe and Casing Under Overpass •' EIl�f Xa-* X X X M ZA K X X X K 1P.31-K-X-* X 1f X X X X X X z.X X X K X it V,* _ y - - 2, -- s— 0 REMOVE EXIST 12" WATER (SEE CITY OF SLO STD DET 6050) — D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 8 Page 254 of 1059 Summary Established above, there are pros and cons for all options. Below, Table 3 illustrates these differences, while Figure 8 shows approximate locations of each option. Based on the costs associated with the options for constructing a new crossing of US 101, Consor recommends that Option 4 be pursued by the City assuming that the existing water main and casing is in good condition. The City could pursue one of the other alternatives at a later date to provide additional east west connectivity in the area. Table 3: Summary Jack and Bore Under • Highway • Shorter span of pipe Less impact to surroundings Northern Extension of • Minimal, if any, Traffic Calle Joaquin Main Control • Easier to construct and maintain Waterline Over New • Traffic Control goes Overpass hand -in -hand with the construction of the I overpass Casing of 12-inch line in Prado Shortest run of pipe Most cost effective of all options • Harder to maintain due to $1,150,000.00 being within a highway • Possible difficulty in acquiring qualified contractor • Need for easements • Not within current project APE, additional environmental review required • Larger impact to $2,300,000.00 surroundings • Need for easements • Not within current project APE • Environmental Review required • Most costly option • Harder to maintain due to $1,190,000.00 being underneath the highway overpass • Difficult to construct • Still buried underneath $75,000.00 the overpass • Assumes acceptable condition of existing pipe and casing crossing highway. D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 9 Page 255 of 1059 �.r Option 1B: Elks Lane (New) to Embassy Suites Parking Lot w^ Jack-B-Bore Figure 8: General Map of All Options Option 1A El Mercado to Elks Lane (Old) Jack-B-Bore ■ ��� ■ nu i7• Bill M ll Biu milli WA4Option 4: Casing of 12-inch line in Prado ' I Ir ?i Option 2: Northern Extension of Calle Joaquin Main D218721CA.00 • April 2026 • City of San Luis Obispo Prado Road Interchange • 10 Page-256 of 1059 n consor CITY OF SAN LUIS OBISPO Draft Prado Road Interchange Project Bridge Type Selection Report 05-SLO-101 PM 26.8/27.3 P I D 0516000105 July 2, 2026 PREPARED BY: Consor Point of Contact: Dace Morgan, PE 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95630 p: 916.368.9181 e: dace.morgan@consoreng.com PREPARED FOR: City of San Luis Obispo 919 Palm Street San Luis Obispo, CA 93401 Page 257 of 1059 Type Selection Revisions Revision I Date I Description July 2, 2026 1 Draft Type Selection Memo Page 258 of 1059 Prepared by: Tyler Eaton, Bridge Project Engineer Under the Supervision of: Scott McCauley, Lead Structure Project Engineer Submitted by / QROFESSIONq�\ w Tyler Z. Eaton m No. C89407 s�qT CIVIL F OF CA / QROFESSIONq�\ wScott McCauley No. C71495 CIVIL �P 9TF OF C A\-\O 07/02/2026 (916) 368-9181 Dace Morgan, Deputy Project Manager Date Consor North America, Inc. Telephone Page 259 of 1059 DRAFT Table of Contents Chapter 1 General Information ............................................ 1-1 1.1 Structure Type Selection Summary..................................................................................................1-1 1.2 Introduction.....................................................................................................................................1-1 1.3 General Description.........................................................................................................................1-2 1.4 Project History.................................................................................................................................1-2 1.5 Existing and Proposed Nearby Facilities...........................................................................................1-3 1.6 Funding............................................................................................................................................1-4 1.7 Impacts to Traffic.............................................................................................................................1-4 1.8 Staging Areas and Contractor Access...............................................................................................1-4 1.9 Right of Way.....................................................................................................................................1-5 1.10 Hydraulic Considerations...............................................................................................................1-5 1.10.1 Floodploin...............................................................................................................................1-5 1.10.2 Scour.......................................................................................................................................1-5 1.10.3 Drainage.................................................................................................................................1-6 1.11 Geotechnical Considerations.........................................................................................................1-7 1.12 Seismic Ground Motion.................................................................................................................1-7 1.13 Liquefaction and Lateral Spreading Potential................................................................................1-7 1.14 Horizontal Layout...........................................................................................................................1-8 1.15 Vertical Profile................................................................................................................................1-8 1.15.1 Folsework................................................................................................................................1-9 1.16 Structure Layout............................................................................................................................1-9 1.17 Design Exceptions........................................................................................................................1-10 1.18 Design Criteria..............................................................................................................................1-10 1.18.1 Corrosion...............................................................................................................................1-10 1.18.2 Scour.....................................................................................................................................1-10 1.19 Utilities.........................................................................................................................................1-11 1.20 General Aesthetics.......................................................................................................................1-11 1.21 Approach Slabs.............................................................................................................................1-11 1.22 Environmental Studies and Permits.............................................................................................1-11 D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection INge At of 1059 DRAFT Chapter 2 Prado Road West Overcrossing......................... 2-12 2.1 Preferred Structure Type Summary...............................................................................................2-12 2.2 Structure Type Alternatives...........................................................................................................2-13 2.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred)............................2-13 2.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Crider.............................2-13 2.2.3 Other Alternatives...................................................................................................................2-13 2.3 Foundations...................................................................................................................................2-14 2.3.1 Bents.......................................................................................................................................2-14 2.3.2 Abutments..............................................................................................................................2-14 2.4 Constructability..............................................................................................................................2-14 2.4.1 Folsework................................................................................................................................2-14 2.4.2 Deep Foundations...................................................................................................................2-15 2.4.3 MSE Wall "Island"...................................................................................................................2-15 2.5 Barriers...........................................................................................................................................2-16 2.6 Aesthetics.......................................................................................................................................2-16 2.7 Cost Estimate.................................................................................................................................2-16 2.8 Recommendation...........................................................................................................................2-16 Chapter 3 Prado Road East Overcrossing ......................... 3-17 3.1 Preferred Structure Type Summary...............................................................................................3-17 3.2 Structure Type Alternatives...........................................................................................................3-18 3.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred)............................3-18 3.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Crider.............................3-18 3.2.3 Other Alternatives...................................................................................................................3-18 3.3 Foundations...................................................................................................................................3-19 3.3.1 Bents.......................................................................................................................................3-19 3.3.2 Abutments..............................................................................................................................3-19 3.4 Constructability..............................................................................................................................3-19 3.4.1 Falsework................................................................................................................................3-19 3.4.2 Deep Foundations...................................................................................................................3-19 3.4.3 MSE Wall "Island"...................................................................................................................3-20 3.5 Barriers...........................................................................................................................................3-20 3.6 Aesthetics.......................................................................................................................................3-20 D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 2 Page 261 of 1059 DRAFT 3.7 Cost Estimate.................................................................................................................................3-20 3.8 Recommendation...........................................................................................................................3-21 Chapter 4 US 101 Northbound Off -Ramp Structure .......... 4-22 4.1 Preferred Structure Type Summary...............................................................................................4-22 4.2 Structure Type Alternatives...........................................................................................................4-23 4.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred)............................4-23 4.2.2 Cast -in -Place, Conventional Reinforced Concrete Box Girder..................................................4-23 4.2.3 Other Alternatives...................................................................................................................4-23 4.3 Foundations...................................................................................................................................4-24 4.3.1 Bents.......................................................................................................................................4-24 4.3.2 Abutments..............................................................................................................................4-24 4.4 Constructability..............................................................................................................................4-24 4.4.1 Falsework................................................................................................................................4-24 4.4.2 Deep Foundations...................................................................................................................4-24 4.4.3 MSE Wall "Island"...................................................................................................................4-25 4.5 Barriers...........................................................................................................................................4-25 4.6 Aesthetics.......................................................................................................................................4-25 4.7 Cost Estimate.................................................................................................................................4-25 4.8 Recommendation...........................................................................................................................4-25 Chapter 5 US 101 Northbound On -Ramp Structure ............ 5-1 5.1 Preferred Structure Type Summary.................................................................................................5-1 5.2 Structure Type Alternatives.............................................................................................................5-2 5.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred)..............................5-2 5.2.2 Cast -in -Place, Conventional Reinforced Concrete Box Girder....................................................5-2 5.2.3 Other Alternatives.....................................................................................................................5-2 5.3 Foundations.....................................................................................................................................5-3 5.3.1 Bents.........................................................................................................................................5-3 5.3.2 Abutments................................................................................................................................5-3 5.4 Constructability................................................................................................................................5-3 5.4.1 Falsework..................................................................................................................................5-3 5.4.2 Deep Foundations.....................................................................................................................5-3 5.4.3 MSE Wall "Island".....................................................................................................................5-4 D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report 2 P�g�... 1059 DRAFT 5.5 Barriers....................................................................................................... 5.6 Aesthetics................................................................................................... 5.7 Cost Estimate............................................................................................. 5.8 Recommendation....................................................................................... Appendices Appendix A: 35% Bridge Plans Appendix B: 35% Bridge Cost Estimates Appendix C: Geometric Approval Drawings (GAD) Approval Memo Appendix D: Approved Bridge Site Data Submittal (BSDS) Appendix E: Preliminary Bridge Design Hydraulic Study (BDHS) Appendix F: Draft Structure Preliminary Geotechnical Report (SPGR) Bridges D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 263 of 1059 Bridge Type Selection Report • Page 4 DRAFT CHAPTER 1 GENERAL INFORMATION 1.1 Structure Type Selection Summary Table 1-1 1 Project Identification Table 1-2 1 Bridge Information and Cost Recommended Bridge Name Bridge Number Project Type Construction Cost Structure Type Prado Road CIP/PT Reinforced West TBD New Bridge Concrete Box $26,392,000 Overcrossing Girder CIP/PT Reinforced Prado Road East TBD New Bridge Concrete Box $19,057,000 Overcrossing Girder CIP/PT Reinforced US 101 Northbound TBD New Bridge Concrete Box $8,151,000 Off -Ramp Girder CIP/PT Reinforced US 101 Northbound TBD New Bridge Concrete Box $9,427,000 On -Ramp (BRIDGE) Girder $63,027,000 PROJECT TOTAL 1.2 Introduction The U.S. Route 101 (US 101)/Prado Road Interchange Project (Prado Road Interchange) is being developed by the City of San Luis Obispo (City). The purpose of the project is to extend Prado Road over U.S. 101 to connect with Dalidio Drive and reconstruct the existing U.S. 101 northbound on- and off -ramp connections to Prado Road in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the City of San Luis Obispo on U.S. 101 PM 26.8. The project limits extend from PM 26.5 to PM 27.3. The project is located within Caltrans District 5 in the City of San Luis Obispo, San Luis Obispo County. The project area is located within Township 31 South, Range 12 East, on the U.S. Geological Survey (USGS) San Luis Obispo, California 7.5-minute quadrangle. D218721CA.00 • July 2026 • Prado Road Interchange • City of S PLuis sDo f 1059 Bridge Type Selection Rep a ��++ DRAFT 1.3 General Description 0 2.5 5 Miles 1 r I Figure 1-1 1 Vicinity Map Los Padres National Forest lbispo Grover Beach Arroyo Grande P. .ti w w, A total of four (4) bridge structures is proposed as a part of the improvements for the Prado Road Interchange. The Prado Road Western Overcrossing and Eastern Overcrossing provide access across US 101, and the On -Ramp and Off -Ramp Structures provide access to and from US 101, respectively. This type selection report discusses the recommended structure types for each of these (4) bridge structures and summarizes their lengths and structure depths. The On -Ramp and Off -Ramp structures and a portion of the west overcrossing over US 101 are within Caltrans Right-of-way. The General Plans of these bridge structures are included in Appendix A. 1.4 Project History The US 101/Prado Road Interchange is a project that has been discussed, studied, and developed since the early 1990's. Over time, the project plan has progressed from an overcrossing to a full interchange and from a full interchange to the current overcrossing with northbound ramps. One of the reasons for the overcrossing/interchange was the potential development of the Dalidio property on the west side of US 101 between Madonna Road and Los Osos Valley Road (LOVR). Throughout the years, the Dalidio development took on many forms and land uses with many starts and stops as is common for development. The earliest planning document for the full interchange was a Project Study Report (PSR) prepared by Nolte and Associates for the City of San Luis Obispo and Caltrans in 1996. The PSR studied three alternatives for a full interchange: D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-2 Page 265 of 1059 DRAFT ➢ Tight diamond ➢ Spread diamond ➢ Spread diamond with a cloverleaf southbound off -ramp Because of interchange spacing issues with Madonna Road, a southbound collector -distributor roadway on the west side of US 101 to link Madonna Road and Prado Road was proposed to address the limited weaving distance on southbound US 101. At the time of the 1996 PSR, one of the primary drivers of the project, the Dalidio development to the west of the project, did not move forward and there was no support from Caltrans HQ to approve a design exception for the interchange spacing between Madonna and Prado. Without developer funds to help offset construction costs and the Caltrans design exception hurdle, the Prado Interchange project laid dormant until the mid 2010's. In 2014, Coastal Community Builders (CCB) known as MI San Luis Ranch, LLC, initiated an application to develop the Dalidio property. The San Luis Ranch development would include housing, affordable housing, recreation, retail, and commercial spaces with an emphasis on Farm to Table to honor the agricultural history of the property. With the development moving forward, the need for an overcrossing at Prado Road became necessary once again. A 2018 Project Study Report/Project Development Support (PSR/PDS) noted that because of interchange spacing and forecast traffic needs, the 1996 solution of a full interchange with a collector -distributor was deemed invalid. Alternatives were advanced in the PSR/ PDS for the overcrossing and northbound ramps only. Subsequent traffic evaluations and the 2023 Traffic Operations Assessment Report (TOAR) amendment completed as part of the Project Approval and Environmental Document (PA&ED) supported designs for a refined overcrossing, northbound ramps, and a ramp terminal intersection. These recommendations are proposed to being advanced for final design and implementation. 1.5 Existing and Proposed Nearby Facilities US 101 is the principal north/south freeway/expressway on the Central Coast traversing the counties of Santa Barbara, San Luis Obispo, Monterey and San Benito within District 5. It serves local, regional and interregional travel needs, including business, recreation, tourism, journey -to -work, freight and goods movement, and national defense transport and is part of the Pacific Coast Bicycle Route. Through the project area, US 101 is a four lane freeway with 12-foot through lanes, 5-foot inside shoulder, 10-foot outside shoulder and approximately 27-foot median. Right -of -Way width varies, but is generally 177 feet. The nearest interchanges on either side of the project study area include Los Osos Valley Road located at PM 25.9 and Madonna Road located at PM 27.5. There is an existing northbound US 101 off -ramp to Prado Road and an existing Prado Road northbound on -ramp to US 101. The ramp connections to Prado Road are located at PM 26.8. Prado Road, classified as a minor arterial according to the Caltrans California Road System (CRS) maps, is currently a two-lane facility that spans roughly one mile from its intersection with US 101. The area surrounding the project includes commercial uses northwest of the intersection of Prado Road and U.S. 101, commercial and residential uses northeast of said intersection. Several key public service and transportation -related facilities are located along the Prado Road corridor and are relevant to the proposed project. These include the City's Water Resource Recovery Facility (WRRF), the 40 Prado Homeless Services Center, and the adjacent 46 Prado site. In addition, a nearby transit D218721CA.00 • July 2026 • Prado Road Interchange • City of S PLuis Bridge Type Selection Rep a f 1059 DRAFT operations facility serving local and regional bus services contributes to transit -related vehicle movements in the area. The San Luis Ranch property is currently in the initial phases of development, with approved commercial, residential, recreational, and agricultural land uses under the San Luis Ranch Specific Plan, adopted by the City in 2017. There is a roundabout within this development at the intersection of Froom Ranch Way and Dalidio Drive that was constructed with the ability to incorporate an intersection with the future extension of Prado Road to the west US 101. The project also includes realignment of the Elks Lane intersection to accommodate the footprint of the proposed interchange improvements. The existing Elks Lane connection to Prado Road would be removed due to its conflict with the planned U.S. 101 northbound on- and off -ramp terminal intersection at Prado Road. To maintain local access and circulation, Elks Lane would be realigned to intersect Prado Road east of its current location, adjacent to the 40 Prado Homeless Services Center. On the eastern end of the Prado Road alignment the project abuts the western limits of the San Luis Obispo Creek Bridge Widening Project, which has independent utility from the proposed project and is currently being reviewed by the City of San Luis Obispo. This project includes widening the existing 2-lane bridge to provide a total of six lanes and a sidewalk on each side of the bridge. 1.6 Funding It has been determined thatthis project is eligible for Federal -aid funding. The City plans to fund the project with a combination of impact fees, debt financing, and the SLOCOG Regional Transportation Improvement Program (RTIP). The PA&ED, PS&E, and Right -of -Way support phases are programmed with 100% local funds. The Construction phase has nearly $64 million currently programmed from a combination of RTIP and local funding sources. The City will continue to pursue additional funds through other state and federal grants. 1.7 Impacts to Traffic For construction of the Prado Road Western Overcrossing, full freeway closures would be required for falsework erection and removal if the superstructure is constructed with the cast -in -place alternative. This may call for detours and/or median crossovers, which will be addressed in the PS&E phase. It will also need to be determined whether the current ramp configuration at Prado Road will remain open during construction, and if they can be used for the northbound detour. Southbound closure will be more complicated, possibly requiring use of a median crossover, or detourvia Madonna Road and Los Osos Valley Road. Mainline closures of US 101 will be allowed at night only. A detour for Elks Lane will also need to be implemented during construction. A preliminary Transportation Management Plan (TMP) Data Sheet/Checklist was previously prepared for this project and was included in the Project Report. 1.8 Staging Areas and Contractor Access Access to the site is not anticipated to be limited due to its proximity to US 101 within San Luis Obispo. Construction staging areas are anticipated to be located within the closed portion of Prado Road to the east of US 101 and the undeveloped area to the west of US 101. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 267 of 1059 Bridge Type Selection Report • Page 1-4 DRAFT 1.9 Right of Way An encroachment permit from Caltrans will need to be obtained for portions of the western overcrossing constructed within Caltrans right-of-way. Right-of-way acquisition will be required for portions of the western overcrossing to the west of US 101. Temporary construction easements may be required to establish sufficient area for construction staging areas. 1.10 Hydraulic Considerations The project is within the limits of the floodplain of San Luis Obispo Creek. Accordingly, HDR, Inc. (HDR) has provided a Preliminary Bridge Design Hydraulic Study (BDHS) for this project, and is included in Appendix E. The Preliminary BDHS was developed in accordance with Caltrans Structure Technical Policy (STP) 2.6, and includes: ➢ A review of available hydrologic data ➢ Hydrologic analyses ➢ Hydraulic analyses to determine design water surface elevations and flow velocities for existing and proposed conditions ➢ Scour analyses to estimate potential scour depths for the proposed condition 1.10.1 Floodplain All structures are located within the San Luis Obispo Creek Splitflow floodplain, which is categorized as a Zone AE Regulatory Floodway based on FEMA Flood Maps. The layout of the structures for this project was partly governed by the need to satisfy both FEMA and City requirements for allowable rises in water surface elevation in the floodplain between existing and proposed conditions. The analysis included in the Preliminary BDHS indicates that the proposed condition for this project results in a maximum change in water surface elevation of only 0.3 feet. 1.10.2 Scour Scour for both the 100-Year and 200-year flood events is evaluated in the Preliminary BDHS. The scour at each bridge support is summarized in the tables below. D218721CA.00 • July 2026 • Prado Road Interchange • City of S PLuis � Bridge Type Selection Rep a�5 f 1059 DRAFT Table 1-3 1 100-Year Flood Scour Values Table 1-4 1 200-Year Flood Scour Values 1.10.3 Drainage Caltrans Standard Plan type D-1 deck drains will be required for all the east and west overcrossings as well as the on and off Ramps. Deck drains will connect to City sewer systems where applicable or outlet into drainage swales for onsite treatment. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 269 of 1059 Bridge Type Selection Report • Page 1-6 DRAFT 1.11 Geotechnical Considerations Yen and Associates, Inc. (Yeh) has prepared a Draft Structure Preliminary Geotechnical Report (SPGR) for the bridge structures included in this project and is included in Appendix F. The Draft SPGR includes a discussion of project alternatives, site conditions, geologic conditions, seismicity and faulting, geotechnical considerations regarding the overcrossings and ramp structures foundation alternatives, and additional field and laboratory data needed for design. The preliminary characterization of the subsurface conditions is based on boring information from previous explorations performed in the vicinity of the project site as well as cone penetration test (CPT) soundings performed for Phase 1 of this project. The Draft SPGR identifies cast -in -drilled -hole (CIDH) piles as generally the most suitable foundation support for each of the structures. The CIDH piles are recommended to be embedded below the compressible and liquefiable (if present) layers and bearing within the Francisan melange bedrock. The bedrock is located approximately 60 feet below the ground surface based on the available data. The Draft SPGR also identifies that both driven and cast -in -steel -shell (CISS) piles are considered feasible alternatives for this site. 1.12 Seismic Ground Motion The seismic data for the project was generated by Yen using selected site parameters and AIRS Online version 4.0 to estimate ground motion parameters in accordance with Appendix B of the Caltrans Seismic Design Criteria (SDC) version 2.1, dated January 2025. Seismic data was generated for the Safety Evaluation Earthquake, which is defined as an earthquake with a 975-year return period. The shear wave velocity for the project site was estimated from the CPT data obtained by Yeh at the project site. The preliminary design response spectrum for the project is provided in Figure 1-2 below. For additional information, see the Draft SPGR prepared by Yeh included in Appendix F. L4 L2 3 1 D.8 0.6 0.4 0.2 �I1 1` I 0.0 1.0 2.0 10 4.0 5.0 &0 7.0 &0 9.0 10.0 Fedod, T (aec) — -Design Response Spectrum 0 Peak Ground Accleration=0.39g ARSOnline V4.0 Mean Magnitude: 7.05 at 25.37 km Spectral Damping: 5 percent Latitude 35.2569dees Longitude.-120.6748 degrees V, �: 320 meter4secord Figure 1-2 1 Preliminary Design Response Spectrum 1.13 Liquefaction and Lateral Spreading Potential Based on CPT soundings, potentially liquefiable medium dense layers of sand were encountered at depths of 44 to 55 feet below the ground surface. Liquefiable materials are not likely to impact roadways or surface D218721CA.00 • July 2026 • Prado Road Interchange • City of S Luis 0 Bridge Type Selection RepI�g�PaVPf 1059 DRAFT improvements, but could have an impact on deep foundations for the project. Additional subsurface explorations will be required to verify if there are liquefiable layers and if it will be a design constraint. Liquefaction -induced lateral spreading is not a consideration for the design of the overcrossings and ramp structures based on review of previous data collected at the site and the CPT soundings performed for this project. 1.14 Horizontal Layout The horizontal alignment and typical section of each of the structures are governed by the roadway design criteria that was agreed upon in conjunction with the City and Caltrans considering the volume of traffic and design speed. The design criteria for both Prado Road and the On & Off -Ramps are included in the "Design Criteria Memorandum" prepared for this project by Consor. The typical section geometry parameters are summarized for each structure in the table below. Table 1-5 1 Roadway Typical Sections Structure Travel Lanes Shoulders Sidewalk Prado Road Western 2-12' Lanes and 1-11' Left EOD — 4' minimum & Left EOD — 6' Sidewalk Overcrossing Median/Turning Lane varies minimum & varies Right EOD — 4' Right EOD — 14'Sidewalk minimum & varies Prado Road Eastern 1- Lane, 3-11' Lanes', Left EOD — 5' Left EOD — 6' Sidewalk Overcrossing and 1-11' Median Right EOD — 5' Right EOD —14' Sidewalk US 101 On -Ramp 1-12' Lane minimum & Left EOD-4' minimum & N/A Structure varieSZ varies Right EOD —8' minimum 2-11' Lanes & varies US 101 Off -Ramp Left EOD —4' N/A Structure Right EOD — 8' Note: 1. Southernmost eastbound lane width transitions from 0' to 11' on the eastern overcrossing. 2. Travel lane width is roughly 16-feet minimum on the on -ramp structure. The layout of the abutments and intermediate bents of the western overcrossing are governed by the minimum horizontal clearance required by Section 309.1 of the Caltrans Highway Design Manual (HDM). The Caltrans HDM requires that supports be located a minimum of 20-feet beyond each edge of travel way for US 101. 1.15 Vertical Profile The vertical profile of each of the structures is primarily governed by the required vertical clearance between the soffit of the Prado Road West Overcrossing and the existing profile of US 101. Section 309.2 of the Caltrans HDM indicates that a minimum of 16.5-feet of vertical clearance must be provided for structures spanning over highways. The vertical profiles were also developed to meet the freeboard requirements listed in the Caltrans Structure Technical Policy (STP) 2.6. STP 2.6 indicates that the soffit of each of the structures must provide at least 2-feet of freeboard over the 50-year flood and at least convey the 100-year flood with no freeboard. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 271 of 1059 Bridge Type Selection Report • Page 1-8 DRAFT 1.15.1 Falsework In addition to the clearance requirements over US 101 for the permanent condition, there are temporary clearance requirements that the vertical profile of the western overcrossing would need to meet if falsework is required for construction. Falsework would be required if cast -in -place construction methods are used for the construction of the superstructure for the western overcrossing. Section 204.8 of the Caltrans HDM requires that a minimum vertical falsework clearance over US 101 of 15 feet must be provided. It should be evaluated for a cast -in -place superstructure alternative if this required temporary vertical clearance, considering the anticipated depth of falsework for the minimum falsework span lengths over US 101, can be feasibly provided. 1.16 Structure Layout The alignments of the overcrossing, on -ramp, and off -ramp structures intersect directly adjacent to US 101 on its east side. Previous studies of the floodplain for this project had determined that the overcrossing would have needed to span approximately 1050 feet between the west and east approaches in order to limit water surface elevation impacts to an acceptable amount. This would have required the ends of the on -ramp and off -ramp superstructures to directly connect to a span of the overcrossing, which would lead to nonstandard detailing and construction methods, more unpredictable seismic performance, and increases in construction cost. The Consor team has since performed more detailed Top of Barrier Superstructure hydrologic and hydraulic analyses of the floodplain to aid in the preparation of the Preliminary BDHS. Iterations of these analyses were performed to determine the most cost-efficient structure layout that ' still meets the requirements for impacts to the q floodplain. It was determined that reducing the total > 5'-0" ^� Al length of the overcrossing to 750 feet would be IF acceptable through these iterations of the analyses. This led to converting the easternmost span of the overcrossing to a bridge approach supported by MSE — — — — —— walls, and more notably implementing an "island" of MSE MSE wall at the structure intersection directly east of US — — — — — — — 101. The proposed island support will be composed of a Mechanically Stabilized Embankment Abutment — — — — — — — 2— (MSEA) Type 2 (per Caltrans Memos to Designers 5-1) FG that spans the entire perimeter of this intersection and �_4 . — is offset to provide a minimum clearance between in the front of the MSE wall and the abutment of Figure 1-3 1 MSEA Type 2 Diagram (MTD 5-1) each of the four structures. The implementation of the MSEA Type 2 splits the overcrossing into two separate structures, western and eastern, and provides cost savings and more predictable seismic performance compared to the previously proposed elevated intersection. The cost savings are primarily associated with the reduction in retained height of the abutments, reducing vertical and overturning loads on the deep foundations. Further discussion of the island support is included in the separate Type Selection Report developed for the retaining walls for this project. D218721CA.00 • July 2026 • Prado Road Interchange • City of S Luis �o Bridge Type Selection ReI: 90f 1059 DRAFT 1.17 Design Exceptions No design exceptions related to the bridge design are currently anticipated for this project. 1.18 Design Criteria The design criteria for the bridge structures are primarily based on the codes and guidelines below. See the Design Criteria Memorandum for the Road and Bridge, both included in the Appendix, for further information. ➢ Road Design Roadway design will be based on AASHTO "Guidelines for Geometric Design of Low -Volume Roads 2019 (2"d Edition)" (GDLVR) supplemented with AASHTO "A Policy on Geometric Design of Highways and Streets 2018 (7th Edition)" (Green Book), and County Public Improvement Standards 2022 where applicable. ➢ Bridge Design Bridge design will be performed in accordance with "AASHTO LRFD Bridge Design Specifications (8th Edition)", and the "Caltrans Amendments (dated April 2019)". The latest versions of the Caltrans bridge design manuals, Bridge Design Memos (BDMs), and Structure Technical Policies (STPs) at the time of type selection will also be utilized in the design. ➢ Seismic Design Seismic design will be performed in accordance with the Caltrans "Seismic Design Criteria Version 2.1 (February 2025)" and the latest information available from Caltrans Earthquake Research. All bridge structures will be categorized as "Ordinary Standard" bridges. ➢ Hydraulic Design The hydraulics design will be in accordance with Caltrans STP 2.6 "Hydraulic Design for Structures over Waterways". The proposed bridge soffit will be located a minimum of 2 feet above the 50-year flood elevation, or convey the 100-year flood (i.e., no freeboard), whichever is greater. 1.18.1 Corrosion The Draft SPGR indicates that the soils at the site are not corrosive. Standard concrete cover and conventional uncoated reinforcement details will be used for the design. Freeze thaw is not a concern at this site. 1.18.2 Scour In accordance with Caltrans STP 2.6, the bridge design will consider scour for the 100-year flood event (Scour Design Flood) along with scour for the 200-year flood event (Scour Check Flood) for the Extreme II limit state. The bottom of the pile caps for the abutments will be located below the total scour elevation for the Scour Design Flood with the exception of abutments supported by the MSEA Type II wall. In accordance with guidance provided by Tony Nedwick with Caltrans Structures Hydraulics, the pile caps for the abutments at the MSEA Type II wall do not need to be located below the total scour elevation of the Scour Design Flood as long as the abutment piles are designed to be stable under scoured conditions while neglecting any support of the MSEA Type II wall. The piles for the four abutments located at the MSEA Type II wall will be designed accordingly. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 273 of 1059 Bridge Type Selection Report • Page 1-10 DRAFT 1.19 Utilities Various utilities located within the vicinity of the project site will either be relocated or remain in place during construction. Among these utilities is an oil line owned by Phillips 66, which will be relocated with sufficient clearance awayfrom the US 101 NB Off -Ramp and Prado Road Eastern Overcrossing foundations. Two proposed water lines, each owned by the City and 12 inch in diameter, will be located underground along Prado Road. It is anticipated that the only utilities that will be carried on the bridge structures will be smaller dry utilities (6 inch diameter maximum) located within the sidewalks on the overcrossings. 1.20 General Aesthetics Consor and Apexx Architecture, LCC (Apexx), a subconsultant, are in the process of developing preliminary concepts for the overall aesthetics for the project. These preliminary concepts are being developed with the goal of achieving consensus for the direction of the overall aesthetics of the project with all stakeholders involved, including the City and Caltrans, while maintaining consistency with the requirements of the Visual Impact Assessment for the project. Structural elements of the bridge structures that may receive architectural treatment for developing the aesthetics of the project potentially include the barriers, railing, lighting, columns, bent caps, and other elements. 1.21 Approach Slabs Structure Approach Type N (30) approach slabs per the Caltrans Standard Plans will be implemented at all bridge approaches in accordance with Caltrans STP 2.2. 1.22 Environmental Studies and Permits SWCA, Inc. will conduct and prepare the technical studies, prepare the California Environmental Quality Act (CEQA) document, and prepare project permit applications. The County will be the lead agency for CEQA, and the anticipated document will be an Initial Study Mitigated Negative Declaration (IS/MND). Caltrans will be the lead agency for the National Environmental Policy Act (NEPA), and the anticipated document will be a Categorical Exclusion (CE). The project is not expected to result in any negative impacts to native plant or animal species. SWCA will prepare permit applications after environmental clearance is obtained shown below. Note the City will be responsible for obtaining an encroachment permit from Caltrans for all work within Caltrans right-of-way. Table 1-6 1 Permits D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis9-4 o Bridge Type Selection RepoYtpf 1059 DRAFT CHAPTER 2 PRADO ROAD WEST OVERCROSSING 2.1 Preferred Structure Type Summary Table 2-1 1 Structure Summary — Prado Road Western Overcrossing Bridge Name Prado Road West Overcrossing over US 101 Bridge Number TBD Structure Type Cast -In -Place, Post -Tensioned Reinforced Concrete Box Girder Structure Cost $26,392,000 Spans Span 1-3 = 150'-0"; Total Length = 450'-0" Structure Depth 6'-0" Depth -to -Span Ratio Spans 1-3: 0.040 65'-4" minimum total width and varies starting at Bent 3 to 89'-10" maximum total Structure Width width at Abut 4, including: ■ 2-12'-0" Lanes ■ 1-11'-0" Median/Turning Lane ■ 14-0" Minimum & Varies Shoulder at LEOD ■ 14-0" Shoulder at REOD ■ 6'-0" Minimum & Varies Sidewalk at LEOD ■ 14'-0" Minimum & Varies Sidewalk at REOD Crowned at "P" Line with 2% cross slope each direction Profile Abutments T Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 4: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2 & 3: Integral bent cap with a single row of 3 - 5'-0" diameter columns pinned Bents top founded on 7'-0" diameter Type II CIDH piles Vertical Clearance 16'-6" minimum is met over US 101 2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length 15'-0" minimum is met over US 101 for falsework LEOD: Type 732SW barrier sidewalk width = 6'-0" Temp Vertical Clearance Barriers/Sidewalks REOD: Type 732SW barrier sidewalk width = 14'-0" Abutment 1: Structure Approach Type N (30) Approaches Abutment 4: Structure Approach Type N (Mod) This structure is in a Non -Freeze -Thaw Area, in which deck salting does not occur. Deck Protection No special deck protection is required. Drains Deck Drainage will be required. Drain location and layout are pending. Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments. Temperature Range 10°F to 80°F Joints Abutment 1 & 4: Type B Joint Seal (MR = 2") Anticipated lighting and PG&E electrical conduits will be carried by the overcrossing. Utilities 6" diameter maximum located inside REOD barrier sidewalk. Live Load (LL): HL93 and permit design load Loading Dead Load (DC): Type 732SW barriers and railing Additional Dead Load (DW): 35 psf for future wearing surface; 100 plf allowance for utilities None. TBD Future Widening Aesthetics D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 275 of 1059 Bridge Type Selection Report • Page 2-12 DRAFT 2.2 Structure Type Alternatives 2.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred) The proposed structure type is a three -span cast -in -place, post -tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and bents supported by a single row of columns founded on Type II Cast -in -Drilled -Hole (CIDH) shafts. The structure depth would be 6 feet total with a total width of 65 feet 4 inches minimum and varies within Span 3 to a maximum width of 89'-10" at Abutment 4. This structure type results in the lowest construction cost and provides visual consistency with other structures within this section of the corridor, such as the LOVR overcrossing. The ability to form the superstructure on -site also provides the advantage of increased constructability and design compatibility with accommodating the horizontal curve on the overcrossing on the western portion. Additionally, a flare in the width of the superstructure near the ramp intersection is required to accommodate an acceptable truck turn radius and an acceptable sight distance, which can be easily incorporated with cast -in -place construction. The primary disadvantage of this alternative includes requiring falsework, creating the need for night closures for its installation and longer construction duration. However, temporary night closures are considered feasible, and the construction duration is not critical for this project. Additionally, the profile of the overcrossing for this alternative would need to consider accommodating a minimum temporary vertical clearance of 15 feet for the falsework over US 101. 2.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grider Due to its span length, a precast alternative would need to include the utilization of California Wide Flange Girders. These girders would be 72 inches deep and support a cast -in -place reinforced concrete topping slab, resulting in a total structure depth of 7 feet. A total of eight girders spaced at approximately 8.25 feet are anticipated to be required to support the full width structure of 65 feet 4 inches. The abutments would be seat type abutments founded on multiple rows of driven steel H-piles and the bents would be a drop bent cap supported on a single row of columns founded on Type II CIDH shafts. Precast alternatives are not typically economical compared to cast -in -place alternatives and are usually only used when falsework installation is not possible or there is a desire to reduce construction duration. Additionally, the horizontal curve on the western end of the bridge would require a more complicated design and more complicated formwork between the girders compared to a cast -in -place alternative. This alternative is considered a feasible, but not preferred alternative for these reasons. This alternative could be considered preferred if the required falsework configuration for the cast -in -place alternative is not feasible or if the aesthetics of the precast girder are desired. 2.2.3 Other Alternatives Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast -in -place and precast alternatives structure types were not considered accordingly. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure. D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis�o f 1059 Bridge Type Selection RepoYt� DRAFT A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. The maximum depth at the bents would be approximately 6-foot 9-inch and the minimum depth at midspan of the intermediate span and near the abutment of the end spans would be approximately 4-foot 6-inch. Disadvantages of this alternative would include inconsistent visual appearance with other nearby structures located within this section of the US 101 corridor, and potentially requiring a raise in profile grade to accommodate the greater structure depth at the intermediate supports. Additionally, even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. 2.3 Foundations 2.3.1 Bents Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 7-foot diameter Type II CIDH shafts were selected to support the 5-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance forvarious sizes of CIDH piles, which indicates that the vertical tip of a 7-foot diameter Type II pile would be roughly 120 feet below the existing ground surface. 2.3.2 Abutments Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more cost- effective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 1 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 4 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project. 2.4 Constructability 2.4.1 Falsework The primary constructability consideration for the preferred alternative is the feasibility of the installation of falsework at this site. The falsework will need to span over each of the northbound and southbound corridors of US 101, which are both composed of two 12-foot lanes, one 5-foot shoulder, and one 10-foot shoulder for a total minimum normal width of traffic opening of 39 feet. Based on the guidance provide in Table 204.8 of the Caltrans HDM, this width would result in a resulting falsework span of up to 51 feet and a minimum falsework depth of 3-foot 1-inch. This guidance is based on the assumption that temporary barriers will be installed at each edge of shoulder that are anchored. The proposed profile of Prado Road and superstructure depth of the overcrossing for the cast -in -place alternative would be in accordance with the minimum vertical clearance requirement of 15 feet based on these assumptions. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 277 of 1059 Bridge Type Selection Report • Page 2-14 DRAFT The erection and removal of the falsework will require night closures of US 101. It will be assessed if detour routes and/or median crossovers are required during the PS&E phase. Additionally, there is an existing stretch of guardrail present in the middle of the median between the northbound and southbound corridors that could potentially conflict with a falsework support. Either the minimum normal width of traffic opening could be reduced, or a section of the existing guardrail could be removed if required for the installation of the falsework support(s) in the median. Figure 2-1 1 US 101 Median (looking northbound) 2.4.2 Deep Foundations The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site. Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater. The following constructability considerations were also provided in the Draft SPGR for driven piles: • Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Pre - drilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances. • Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions. 2.4.3 MSE Wall "Island" The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis�o f 1059 Bridge Type Selection RepoYt� DRAFT around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC 011 and the Type Selection Report for the retaining walls. 2.5 Barriers Both edges of deck will support Caltrans Standard Plan Type 732SW concrete barriers. The Type 732SW barrier on the north side (left edge of deck) will provide a 6-foot wide sidewalk, which is in conformance with the minimum width provide in the standard plan. The Type 732SW barrier on the south side (right edge of deck) will provide a total 14-foot wide sidewalk to incorporate a Class I Bikeway in accordance with the Caltrans HDM. The Type 732SW concrete barriers will support tubular handrailing on Span 1 and Span 2, while Chain Link Railing Type 7 will be supported by the barriers on Span 3 that spans over US 101. Both the handrailing and the chain link railing will be in accordance with the Caltrans Standard Plans. Lighting is also proposed to be installed on the overcrossing. 2.6 Aesthetics Aesthetics are anticipated to be proposed for the western overcrossing, but options are still being evaluated. Typical treatments that could be implemented include: A standard one-way flare at the top of the columns at each bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section. Black paint coating incorporated for the tubular handrailing and chain link railing installed on top of the Type 732SW barriers, for both the desired appearance and to help protect the railing from corrosion. 2.7 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below: Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder o Total Structure Construction Cost = $26,392,000 Alternative 2 — Precast, Prestressed Reinforced Concrete California Wide Flange Girder o Total Structure Construction Cost = $27,649,000 2.8 Recommendation Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. Alternative 2 is also feasible and could be considered further if the installation of falsework in the median of US 101 is infeasible and if the appearance of the precast girders is desired. Additionally, the incorporation of a variable depth superstructure could be further considered if its appearance would be desired. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 279 of 1059 Bridge Type Selection Report • Page 2-16 DRAFT CHAPTER 3 PRADO ROAD EAST OVERCROSSING 3.1 Preferred Structure Type Summary Table 3-1 1 Structure Summary — Prado Road Eastern Overcrossing Bridge Name Prado Road East Overcrossing over US 101 Bridge Number TBD Structure Type Cast -In -Place, Post -Tensioned Reinforced Concrete Box Girder Structure Cost $19,057,000 Spans Span 1-2 = 150'-0"; Total Length = 300'-0" 6'-0" Spans 1-2: 0.040 77'-10" minimum total width at Abut 1 & varies to 87'-4" maximum total width at Structure Depth Depth -to -Span Ratio Structure Width Abut 3, including: ■ 1-12'-0" Lane ■ 3-11'-0" Lanes (Southern eastbound lane width transitions from 0' to 11') ■ 1-11'-0" Median ■ 14-0" Shoulder at LEOD ■ 1-5'-0" Shoulder at REOD ■ 6'-0" Sidewalk at LEOD ■ 14'-0" Sidewalk at REOD Profile Crowned at "P" Line with 2% cross slope each direction Abutments Abut 1: Seat Type Abutment on Two Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2: Integral bent cap with a single row of 4 - 5'-0" diameter columns pinned top Bents founded on 7'-0" diameter Type II CIDH piles Vertical Clearance 2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length N/A LEOD: Type 732SW barrier sidewalk width = 6'-0" Temp Vertical Clearance Barriers/Sidewalks REOD: Type 732SW barrier sidewalk width = 14'-0" Abutment 1: Structure Approach Type N (Mod) Approaches Abutment 3: Structure Approach Type N (30) This structure is in a Non -Freeze -Thaw Area, in which deck salting does not occur. Deck Protection No special deck protection is required. Drains Deck Drainage will be required. Drain location and layout are pending. Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments. Temperature Range 101 to 80° Joints Abutment 1 & 3: Type B Joint Seal (MR = 2") Anticipated lighting and PG&E electrical conduits will be carried by the overcrossing. Utilities 6" diameter maximum located inside REOD barrier sidewalk. Live Load (LL): HL93 and permit design load Loading Dead Load (DC): Type 732SW barriers and railing Additional Dead Load (DW): 35 psf for future wearing surface; 100 plf allowance for utilities None. TBD Future Widening Aesthetics D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis# -P o f 1059 Bridge Type Selection RepoYt� DRAFT 3.2 Structure Type Alternatives 3.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred) The proposed structure type is a two -span cast -in -place, post -tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast -in -Drilled -Hole (CIDH) shafts. The structure depth would be 6 feet total with a total width varying between 77-feet 10-inches and 87-feet 4-inches. This structure type results in the lowest construction cost and provides visual consistency with the on- and off -ramp structures. The ability to form the superstructure on -site provides the advantage of increased constructability and design compatibility with accommodating the varying width of the overcrossing. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project. Additionally, there is no minimum temporary vertical clearance requirement for this project because it does not cross over the freeway. 3.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grrder Due to its span length, a precast alternative would need to include the utilization of California Wide Flange Girders. These girders would be 72 inches deep and support a cast -in -place reinforced concrete topping slab, resulting in a total structure depth of 7 feet. A total of eleven girders with varied spacing at each support are anticipated to be required to support the varied width structure. The abutments would be seat type abutments founded on multiple rows of driven steel H-piles and the bent would be a drop bent cap supported on a single row of columns founded on Type II CIDH shafts. Precast alternatives are not typically economical compared to cast -in -place alternatives and are usually only used when falsework installation is not possible or there is a desire to reduce construction duration. Additionally, the varying width of the overcrossing would require a more complicated design and more complicated formwork between the girders compared to a cast -in -place alternative. This alternative is considered a feasible, but not preferred alternative for these reasons. This alternative could be considered further if reducing the construction duration or if the aesthetics of the precast girder are desired. 3.2.3 Other Alternatives Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast -in -place and precast alternatives structure types were not considered accordingly. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure. A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the eastern D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 281 of 1059 Bridge Type Selection Report • Page 3-18 DRAFT overcrossing because the level of visibility of this structure is anticipated to be lower than the western overcrossing. 3.3 Foundations 3.3.1 Bents Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 7-foot diameter Type II CIDH shafts were selected to support the 5-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance forvarious sizes of CIDH piles, which indicates that the vertical tip of a 7-foot diameter Type II pile would be roughly 120 feet below the existing ground surface. 3.3.2 Abutments Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more cost- effective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Two rows of HP14x89 piles are anticipated at Abutment 3 to sufficiently resist the lateral load demands for a relatively short abutment, while two rows of HP14x89 piles are anticipated to be required at Abutment 1 as well due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project. 3.4 Constructability 3.4.1 Falsework The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the eastern overcrossing does not cross over an open portion of road or freeway. 3.4.2 Deep Foundations The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site. Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater. The following constructability considerations were also provided in the Draft SPGR for driven piles: • Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Pre- D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis o Bridge Type Selection RepoYt� 90f 1059 DRAFT drilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances. • Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions. 3.4.3 MSE Wall "Island" The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC 011 and the Type Selection Report for the retaining walls. 3.5 Barriers Both edges of deck will support Caltrans Standard Plan Type 732SW concrete barriers. The Type 732SW barrier on the north side (left edge of deck) will provide a 6-foot wide sidewalk, which is in conformance with the minimum width provide in the standard plan. The Type 732SW barrier on the south side (right edge of deck) will provide a total 14-foot wide sidewalk to incorporate a Class I Bikeway in accordance with the Caltrans HDM. The Type 732SW concrete barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans. Lighting is also proposed to be installed on the overcrossing. 3.6 Aesthetics Aesthetics are anticipated to be proposed for the eastern overcrossing, but options are still being evaluated. Typical treatments that could be implemented include: • A standard one-way flare at the top of the columns at each bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section. • Black paint coating incorporated for the tubular handrailing installed on top of the Type 732SW barriers, for both the desired appearance and to help protect the railing from corrosion. 3.7 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below: • Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder o Total Structure Construction Cost = $19,057,000 • Alternative 2 — Precast, Prestressed Reinforced Concrete California Wide Flange Girder D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 283 of 1059 Bridge Type Selection Report • Page 3-20 DRAFT o Total Structure Construction Cost = $20,287,000 3.8 Recommendation Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. Alternative 2 is also feasible and could be considered further if reduction in construction duration and/or if the appearance of the precast girders is desired. D218721CA.00 • July 2026 • Prado Road Interchange • City of S Luis s o Bridge Type Selection Repc _i Of 1059 DRAFT CHAPTER 4 US 101 NORTHBOUND OFF -RAMP STRUCTURE 4.1 Preferred Structure Type Summary Table 4-1 1 Structure Summary — US 101 NB Off -Ramp Bridge Name US 101 NB Off -Ramp Bridge Number TBD Structure Type Cast -In -Place, Post -Tensioned Reinforced Concrete Box Girder Structure Cost $8,151,000 Spans Span 1-2 = 125'-0"; Total Length = 250'-0" Structure Depth 5'-0" Depth -to -Span Ratio Spans 1-2: 0.040 39'-6" total width including: ■ 2-12'-0" Lanes ■ 4'-0" Shoulder at LEOD ■ 8'-0" Shoulder at REOD Structure Width Profile Superelevated, with a superelevation transition across its length Abutments Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bents Bent 2: Integral bent cap with a single row of 2 - 4'-0" diameter columns pinned top founded on 6'-0" diameter Type II CIDH piles Vertical Clearance 2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length Temporary Vertical Clearance None. Barriers/Sidewalks LEOD: Type 836 Concrete Barrier REOD: Type 836 Concrete Barrier Approaches Abutment 1: Structure Approach Type N (30) Abutment 3: Structure Approach Type N (Mod) Deck Protection This structure is in a Non -Freeze -Thaw Area, in which deck salting does not occur. No special deck protection is required. Drains Deck Drainage will be required. Drain location and layout are pending. Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments. Temperature Range 10° to 801 Joints Abutment 1 & 3: Type B Joint Seal (MR = 2") Utilities None. Loading Live Load (LL): HL93 and permit design load Dead Load (DC): Type 836 barriers and railing Additional Dead Load (DW): 35 psf for future wearing surface Future Widening None. Aesthetics TBD D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 285 of 1059 Bridge Type Selection Report • Page 4-22 DRAFT 4.2 Structure Type Alternatives 4.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred) The proposed structure type is a two -span cast -in -place, post -tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast -in -Drilled -Hole (CIDH) shafts. The structure depth will be 5 feet total with a total width of 39-feet 6-inches. This structure type results in the lowest construction cost and provides visual consistency with the overcrossing. The ability to form the superstructure on -site provides the advantage of increased constructability and design compatibility with accommodating the horizontal curve on the structure. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project. Additionally, there is no minimum temporary vertical clearance requirement forthis project because it does not cross over the freeway. 4.2.2 Cast -in -Place, Conventional Reinforced Concrete Box Girder A conventional cast -in -place, reinforced concrete box girder alternative could also be feasible for the required span configuration. This structure type would increase its structure depth to a total of 7 feet. The substructure for this alternative would also be composed of seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II CIDH shafts. Even vertical clearance requirements are still met with the increased superstructure depth, this alternative is not considered to be the preferred alternative. The increase in concrete and reinforcement material costs is much greater in comparison to the cost of post -tensioning for Alternative 1. Additionally, the substructure elements would need to increase in size and/or length to support the increased dead loads as a result of an increased superstructure depth. Accordingly, this alternative would not be the most cost- effective structure type. 4.2.3 Other Alternatives Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast -in -place alternatives structure types were not considered accordingly. Precast alternatives were not considered because this structure type is typically less cost-effective than cast -in - place alternatives, especially for a structure with a horizontal curve, substantial vertical curve, and superelevation transition. Additionally, as discussed in the alternatives analysis section for the on -ramp structure, precast is not feasible for both structures. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure. A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the on -ramp because the level of visibility of this structure is anticipated to be lower than the western overcrossing. D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii LuisA 0 Bridge Type Selection RepoYt�pf 1059 DRAFT 4.3 Foundations 4.3.1 Bents Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 6-foot diameter Type II CIDH shafts were selected to support the 4-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 6-foot diameter Type II pile would be roughly 110 feet below the existing ground surface. 4.3.2 Abutments Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more cost- effective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 3 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 1 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project. 4.4 Constructability 4.4.1 Falsework The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the off -ramp structure does not cross over an open portion of road or freeway. 4.4.2 Deep Foundations The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site. Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater. The following constructability considerations were also provided in the Draft SPGR for driven piles: • Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Pre - drilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances. • Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 287 of 1059 Bridge Type Selection Report • Page 4-24 DRAFT 4.4.3 MSE Wall "Island" The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC 011 and the Type Selection Report for the retaining walls. 4.5 B arriers Both edges of deck will support Caltrans Standard Plan Type 836 concrete barriers. The barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans. 4.6 Aesthetics Aesthetics are anticipated to be proposed for the off -ramp structure, but options are still being evaluated. Typical treatments that could be implemented include: A standard one-way flare at the top of the columns at the bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section. Black paint coating incorporated for the tubular handrailing installed on top of the Type 836 barriers, for both the desired appearance and to help protect the railing from corrosion. 4.7 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below: Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder o Total Structure Construction Cost = $8,151,000 • Alternative 2 — Cast -in -Place, Conventional Reinforced Concrete Box Girder o Total Structure Construction Cost = $9,357,000 4.8 Recommendation Alternative 1 — Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. D218721CA.00 • July 2026 • Prado Road Interchange • City of Sk�ii Luis o f 1059 Bridge Type Selection RepoYt� P Page 289 of 1059 DRAFT CHAPTER 5 US 101 NORTHBOUND ON -RAMP STRUCTURE 5.1 Preferred Structure Type Summary Table 5-1 1 Structure Summary — US 101 NB On -Ramp Bridge Name US 101 NB On -Ramp Bridge Number TBD Structure Type Cast -In -Place, Post -Tensioned Reinforced Concrete Box Girder Structure Cost $9,427,000 Spans Span 1-2 = 125'-0"; Total Length = 250'-0" Structure Depth 5'-0" Spans 1-2: 0.040 31'-6" minimum total width at Abut 3 & varies to 67'-0" maximum total width at Abut 1, including: ■ 1-12'-0" Minimum & Varies Lane (16' minimum on structure) ■ 4'-0" Minimum & Varies Shoulder at LEOD ■ 8'-0" Minimum & Varies Shoulder at REOD Depth -to -Span Ratio Structure Width Profile Superelevated, with a superelevation transition across its length Abutments Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bents Bent 2: Integral bent cap with a single row of 2 - 4'-0" diameter columns pinned top founded on 6'-0" diameter Type II CIDH piles Vertical Clearance 2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length None. LEOD: Type 836 Concrete Barrier REOD: Type 836 Concrete Barrier Temporary Vertical Clearance Barriers/Sidewalks Approaches Abutment 1: Structure Approach Type N (Mod) Abutment 3: Structure Approach Type N (30) This structure is in a Non -Freeze -Thaw Area, in which deck salting does not occur. No special deck protection is required. Deck Drainage will be required. Drain location and layout are pending. Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments. Deck Protection Drains Temperature Range 10° to 801 qMr Joints Abutment 1 & 3: Type B Joint Seal (MR = 2") Utilities None. Loading Live Load (LL): HL93 and permit design load Dead Load (DC): Type 836 barriers and railing Additional Dead Load (DW): 35 psf for future wearing surface Future Widening None. Aesthetics TBD D218721CA.00 • July 2026 • Prado Road Interchange • City of S PLuis � Bridge Type Selection Rep a f 1059 DRAFT 5.2 Structure Type Alternatives 5.2.1 Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder (Preferred) The proposed structure type is a two -span cast -in -place, post -tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast -in -Drilled -Hole (CIDH) shafts. The structure depth will be 5 feet total with a varying total width between 31-feet 6-inches and 67-feet. This structure type results in the lowest construction cost and provides visual consistency with the overcrossing. The ability to form the superstructure on -site provides the advantage of increased constructability and design compatibility with accommodating the horizontal curve and varied width of the structure. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project. Additionally, there is no minimum temporary vertical clearance requirement for this project because it does not cross over the freeway. 5.2.2 Cast -in -Place, Conventional Reinforced Concrete Box Girder A conventional cast -in -place, reinforced concrete box girder alternative could also be feasible for the required span configuration. This structure type would increase its structure depth to a total of 7 feet. The substructure for this alternative would also be composed of seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II CIDH shafts. Even vertical clearance requirements are still met with the increased superstructure depth, this alternative is not considered to be the preferred alternative. The increase in concrete and reinforcement material costs is much greater in comparison to the cost of post -tensioning for Alternative 1. Additionally, the substructure elements would need to increase in size and/or length to support the increased dead loads as a result of an increased superstructure depth. Accordingly, this alternative would not be the most cost- effective structure type. 5.2.3 Other Alternatives Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast -in -place alternatives structure types were not considered accordingly. Precast alternatives were not considered because this structure type is typically less cost-effective than cast -in - place alternatives, especially for a structure with a horizontal curve, substantial vertical curve, and superelevation transition. Additionally, the significant difference in width between Abutment 1 and Bent 2, as much as a 27-foot differential, would not be feasible to accommodate with a precast alternative. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure. A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the off -ramp because the level of visibility of this structure is anticipated to be lower than the western overcrossing. D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Page 291 of 1059 Bridge Type Selection Report • Page 5-2 DRAFT 5.3 Foundations 5.3.1 Bents Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 6-foot diameter Type II CIDH shafts were selected to support the 4-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 6-foot diameter Type II pile would be roughly 110 feet below the existing ground surface. 5.3.2 Abutments Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more cost- effective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 1 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 3 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project. 5.4 Constructability 5.4.1 Falsework The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the o1-ramp structure does not cross over an open portion of road or freeway. 5.4.2 Deep Foundations The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site. Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater. The following constructability considerations were also provided in the Draft SPGR for driven piles: • Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Pre - drilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances. • Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions. D218721CA.00 • July 2026 • Prado Road Interchange • City of S PLuis 0 Bridge Type Selection Rep 0 f 1059 DRAFT 5.4.3 MSE Wall "Island" The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC 011 and the Type Selection Report for the retaining walls. 5.5 B arriers Both edges of deck will support Caltrans Standard Plan Type 836 concrete barriers. The barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans. 5.6 Aesthetics Aesthetics are anticipated to be proposed for the off -ramp structure, but options are still being evaluated. Typical treatments that could be implemented include: A standard one-way flare at the top of the columns at the bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section. Black paint coating incorporated for the tubular handrailing installed on top of the Type 836 barriers, for both the desired appearance and to help protect the railing from corrosion. 5.7 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below: Alternative 1— Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder o Total Structure Construction Cost = $9,427,000 • Alternative 2 — Cast -in -Place, Conventional Reinforced Concrete Box Girder o Total Structure Construction Cost = $10,832,000 5.8 Recommendation Alternative 1 — Cast -in -Place, Post -Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. 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No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 550 $ 315 $ 173,250 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 815 $ 525 $ 427,875 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 $ 125 $ 520,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 $ 5,000 $ 320,000 5 490616 84" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 720 $ 4,500 $ 3,240,000 5 500001 PRESTRESSING CAST -IN -PLACE CONCRETE LS LUMP SUM $ 423,100 $ 423,100 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 208 $ 1,400 $ 291,200 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 1565 $ 2,600 $ 4,069,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 900 $ 2,300 $ 2,070,000 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 215 $ 2,000 $ 430,000 10 519100 JOINT SEAL (MR 2") LF 155 $ 225 $ 34,875 11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 880016 $ 2 $ 1,980,036 12 F 833033 CHAIN LINK RAILING (TYPE 7 MODIFIED) LF 315 $ 500 $ 157,500 13 F 833088 TUBULAR HANDRAILING LF 619 $ 300 $ 185,700 14 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 448 $ 600 $ 268,800 15 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 470 $ 750 $ 352,500 16 $ - 17 $ 18 $ 19 $ 20 $ 21 999990 MOBILIZATION LS LUMP SUM $ - $ 1,660,426 SUBTOTAL CONTRACT $ 16,604,262 SUPPLEMENTAL WORK 22 $ 23 $ 24 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 16,604,262 CONTINGENCY 25% $ 4,151,066 ESCALATION 4 Years at 6.19% Per Year $ 5,636,173 TOTAL $ 26,392,000 Page 304 of 1059 Prado Road Western Overcrossing 30% Construction Cost Estimate (Alt 2 - PC/PS CA Wide Flange Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 550 $ 315 $ 173,250 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 820 $ 525 $ 430,500 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 $ 125 $ 520,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 $ 5,000 $ 320,000 5 490616 84" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 720 $ 4,500 $ 3,240,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 208 $ 1,400 $ 291,200 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 486 $ 2,500 $ 1,215,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 949 $ 2,400 $ 2,277,600 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 215 $ 2,000 $ 430,000 10 512211 FURNISH PRECAST PRESTRESSED CONCRETE WIDE FLANGE GIRDER (140'-150') EA 27 $ 115,500 $ 3,118,500 11 F 512401 ERECT PRECAST CONCRETE GIRDER EA 27 $ 36,750 $ 992,250 12 519100 JOINT SEAL (MR 2") LF 155 $ 225 $ 34,875 13 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 659262 $ 3 $ 1,648,155 14 F 833033 CHAIN LINK RAILING (TYPE 7 MODIFIED) LF 315 $ 500 $ 157,500 15 F 833088 TUBULAR HANDRAILING LF 619 $ 300 $ 185,700 16 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 448 $ 600 $ 268,800 17 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 470 $ 750 $ 352,500 18 $ - 19 $ 20 $ 21 $ 22 $ 23 999990 MOBILIZATION LS LUMP SUM $ - $ 1,739,537 SUBTOTAL CONTRACT $ 17,395,367 SUPPLEMENTAL WORK 24 $ 25 $ 26 4-$ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 17,395,367 CONTINGENCY 25% $ 4,348,842 ESCALATION 4 Years at 6.19% Per Year $ 5,904,706 TOTAL $ 27,649,000 Page 305 of 1059 Prado Road Eastern Overcrossing 30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 180 $ 315 $ 56,700 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 297 $ 525 $ 155,925 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 $ 125 $ 520,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 $ 5,000 $ 320,000 5 490616 84" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 480 $ 4,500 $ 2,160,000 6 500001 PRESTRESSING CAST -IN -PLACE CONCRETE LS LUMP SUM $ 317,300 $ 317,300 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 131 $ 1,400 $ 183,400 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 1158 $ 2,600 $ 3,010,800 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 682 $ 2,300 $ 1,568,600 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 231 $ 2,000 $ 462,000 11 519100 JOINT SEAL (MR 2") LF 166 $ 225 $ 37,350 12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 628239 $ 2 $ 1,413,538 13 F 833088 TUBULAR HANDRAILING LF 600 $ 300 $ 180,000 14 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 300 $ 600 $ 180,000 15 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 300 $ 750 $ 225,000 16 $ - 17 $ 18 $ 19 $ 20 $ 21 999990 MOBILIZATION LS LUMP SUM $ - Is 1,198,957 SUBTOTAL CONTRACT $ 11,989,570 SUPPLEMENTAL WORK 22 $ 23 $ 24 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 11,989,570 CONTINGENCY 25% $ 2,997,392 ESCALATION 4 Years at 6.19% Per Year $ 4,069,755 TOTAL $ 19,057,000 Page 306 of 1059 Prado Road Eastern Overcrossing 30% Construction Cost Estimate (Alt 2 - PC/PS CA Wide Flange Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 180 $ 315 $ 56,700 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 297 $ 525 $ 155,925 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 $ 125 $ 520,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 $ 5,000 $ 320,000 5 490616 84" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 480 $ 4,500 $ 2,160,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 130 $ 1,400 $ 182,000 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 305 $ 2,500 $ 762,500 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 768 $ 2,500 $ 1,920,000 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 231 $ 2,000 $ 462,000 10 512211 FURNISH PRECAST PRESTRESSED CONCRETE WIDE FLANGE GIRDER (140'-150') EA 22 $ 110,000 $ 2,420,000 11 F 512401 ERECT PRECAST CONCRETE GIRDER EA 22 $ 35,000 $ 770,000 12 519100 JOINT SEAL (MR 2") LF 166 $ 225 $ 37,350 13 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 454106 $ 3 $ 1,135,265 14 F 833088 TUBULAR HANDRAILING LF 600 $ 300 $ 180,000 15 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 300 $ 600 $ 180,000 16 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 300 $ 750 $ 225,000 17 $ - 18 $ 19 $ 20 $ 21 $ 22 999990 MOBILIZATION LS LUMP SUM $ - $ 1,276,304 SUBTOTAL CONTRACT $ 12,763,044 SUPPLEMENTAL WORK 23 $ 24 $ 25 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 12,763,044 CONTINGENCY 25% $ 3,190,761 ESCALATION 4 Years at 6.19% Per Year $ 4,332,305 TOTAL $ 20,287,000 Page 307 of 1059 Prado Road Interchange Off -Ramp Structure 30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 143 $ 315 $ 45,045 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 306 $ 525 $ 160,650 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2080 $ 125 $ 260,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 32 $ 5,000 $ 160,000 5 490611 72" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 220 $ 3,700 $ 814,000 6 500001 PRESTRESSING CAST -IN -PLACE CONCRETE LS LUMP SUM $ 139,600 $ 139,600 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 93 $ 1,400 $ 130,200 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 441 $ 2,600 $ 1,146,600 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 276 $ 2,300 $ 634,800 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 110 $ 2,000 $ 220,000 11 519100 JOINT SEAL (MR 2") LF 79 $ 225 $ 17,775 12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 248577 $ 2 $ 559,298 13 F 833088 TUBULAR HANDRAILING LF 503 $ 300 $ 150,900 14 F 839741 CONCRETE BARRIER (TYPE 836) LF 503 $ 350 $ 176,050 15 $ - 16 $ 17 $ 18 $ 19 $ 20 999990 MOBILIZATION LS LUMP SUM $ - $ 512,769 SUBTOTAL CONTRACT $ 5,127,687 SUPPLEMENTAL WORK 21 $ 22 $ 23 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 5,127,687 CONTINGENCY 25% $ 1,281,922 ESCALATION 4 Years at 6.19% Per Year $ 1,740,549 TOTAL $ 8,151,000 Page 308 of 1059 Prado Road Interchange Off -Ramp Structure 30% Construction Cost Estimate (Alt 2 - CIP/RC Box Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 143 $ 315 $ 45,045 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 306 $ 525 $ 160,650 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2080 $ 125 $ 260,000 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 32 $ 5,000 $ 160,000 5 490611 72" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 220 $ 4,500 $ 990,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 93 $ 1,400 $ 130,200 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 524 $ 2,500 $ 1,310,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 276 $ 2,500 $ 690,000 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 110 $ 2,000 $ 220,000 10 519100 JOINT SEAL (MR 2") LF 79 $ 225 $ 17,775 11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 395010 $ 3 $ 987,525 11 F 833088 TUBULAR HANDRAILING LF 503 $ 300 $ 150,900 12 F 839741 CONCRETE BARRIER (TYPE 836) LF 503 $ 350 $ 176,050 13 $ - 14 $ 15 $ 16 $ 17 $ 18 999990 MOBILIZATION LS LUMP SUM $ - $ 588,683 SUBTOTAL CONTRACT $ 5,886,828 SUPPLEMENTAL WORK 19 $ 20 $ 21 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 5,886,828 CONTINGENCY 25% $ 1,471,707 ESCALATION 4 Years at 6.19% Per Year $ 1,998,233 TOTAL $ 9,357,000 Page 309 of 1059 Prado Road Interchange On -Ramp Structure 30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 144 $ 315 $ 45,360 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 334 $ 525 $ 175,350 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2470 $ 125 $ 308,750 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 38 $ 5,000 $ 190,000 5 490611 72" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 220 $ 3,700 $ 814,000 6 500001 PRESTRESSING CAST -IN -PLACE CONCRETE LS LUMP SUM $ 176,300 $ 176,300 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 102 $ 1,400 $ 142,800 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 560 $ 2,600 $ 1,456,000 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 326 $ 2,300 $ 749,800 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 137 $ 2,000 $ 274,000 11 519100 JOINT SEAL (MR 2") LF 99 $ 225 $ 22,275 12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 291172 $ 2 $ 655,137 12 F 833088 TUBULAR HANDRAILING LF 504 $ 300 $ 151,200 13 F 839741 CONCRETE BARRIER (TYPE 836) LF 504 $ 350 $ 176,400 14 $ - 15 $ 16 $ 17 $ 18 $ 19 999990 MOBILIZATION LS LUMP SUM $ - $ 593,041 SUBTOTAL CONTRACT $ 5,930,413 SUPPLEMENTAL WORK 20 $ 21 $ 22 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 5,930,413 CONTINGENCY 25% $ 1,482,603 ESCALATION 4 Years at 6.19% Per Year $ 2,013,027 TOTAL $ 9,427,000 Page 310 of 1059 Prado Road Interchange On -Ramp Structure 30% Construction Cost Estimate (Alt 2 - CIP/RC Box Girder) I consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192003 STRUCTURE EXCAVATION (BRIDGE) CY 144 $ 315 $ 45,360 2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 334 $ 525 $ 175,350 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2470 $ 125 $ 308,750 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 38 $ 5,000 $ 190,000 5 490611 72" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 220 $ 4,500 $ 990,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 102 $ 1,400 $ 142,800 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 655 $ 2,500 $ 1,637,500 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 333 $ 2,500 $ 832,500 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 137 $ 2,000 $ 274,000 10 519100 JOINT SEAL (MR 2") LF 99 $ 225 $ 22,275 11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 474930 $ 3 $ 1,187,325 11 F 833088 TUBULAR HANDRAILING LF 504 $ 300 $ 151,200 12 F 839741 CONCRETE BARRIER (TYPE 836) LF 504 $ 350 $ 176,400 13 $ - 14 $ 15 $ 16 $ 17 $ 18 999990 MOBILIZATION LS LUMP SUM $ - $ 681,496 SUBTOTAL CONTRACT $ 6,814,956 SUPPLEMENTAL WORK 19 $ 20 $ 21 $ Bridge Quantities By: T. Eaton Bridge Check By: — Road Quantities By: — Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 6,814,956 CONTINGENCY 25% $ 1,703,739 ESCALATION 4 Years at 6.19% Per Year $ 2,313,277 TOTAL $ 10,832,000 Page 311 of 1059 APPENDIX C: Geometric Approval Drawings (GAD) ntconsor Approval Memo [PENDING CALTRANS REVIEW] Page 312 of 1059 DRAFT APPENDIX D: Approved Bridge Site Data Submittal (BSDS) ntconsor [PENDING CALTRANS REVIEW] Page 313 of 1059 APPENDIX E: Preliminary Bridge Design Hydraulic Study ntconsor BDHS) Page 314 of 1059 F)z Page 315 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Executive Summary The proposed U.S. Route 101 (US 101) at Prado Road Interchange Project (Project) includes improvements to extend Prado Road over US 101 to connect with Dalidio Drive, reconstruct the existing US 101 northbound (NB) off -ramp and on -ramp connections with Prado Road, and construct an auxiliary lane on NB US 101 between the Prado Road and Madonna Road interchanges in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the city of San Luis Obispo in the county of San Luis Obispo at Post Mile (PM) 26.8 and improvements on NB US 101 extend from PM 26.5 to PM 27.3. The preferred alternative includes a partial interchange with the proposed Prado Road overcrossing constructed over US 101, a new US 101 NB off -ramp to Prado Road, and a new NB on -ramp from Prado Road. This Bridge Design Hydraulic Study focuses on the new bridges at US 101 NB off -ramp to Prado Road, US 101 NB on -ramp from Prado Road, the Prado Road west overcrossing, and the Prado Road east overcrossing, which are located within the floodplain of San Luis Obispo Creek. The purpose of this Bridge Design Hydraulic Study is to present the design flow characteristics for San Luis Obispo at the Project site, the hydraulic characteristics associated with the pre -Project (existing condition) and post -Project (proposed condition), and the scour potential for the proposed condition. The proposed bridge design was provided by Consor Engineers and the geotechnical data used for the scour analysis were provided by Yeh and Associates, Inc. The 200-year, 100-year, and 50-year recurrence interval design flows for the Project are based on data from the Federal Emergency Management Agency and calculated using United States Geological Survey equations. A two-dimensional (2D) model was developed for the Project to assess the existing and proposed conditions using the design flows. Grading for the Project was provided by Consor Engineers and was used to develop the proposed condition model. Comparison rasters were generated in the hydraulic model to calculate the differences in water surface elevation (WSE) between the proposed and existing conditions. There are localized increases and decreases in WSE within the vicinity of the Project improvements. During the 100- year storm event, the maximum increase in WSE is 2.4 feet (ft), and it occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in WSE is 1.9 ft, and it also occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. Cross section lines were used to extract data from the 2D model results. The WSEs were extracted along the upstream faces of the Project bridges. The maximum WSEs were extracted, and an average of WSEs along the line were also estimated. The maximum WSE in the proposed condition compared with the maximum WSE in the existing condition increases by 0.1 ft or less. The average WSE in the proposed condition compared with the average WSE in the existing condition increases by 0.3 ft or less. The applicable freeboard criteria for the Project require that the bridges pass the 100-year flow without freeboard and the 50-year flow with 2 ft of freeboard. Based on the results of the hydraulic analysis, the Project bridges will meet the freeboard requirements. The scour potential was evaluated for the proposed bridges using the scour design flood, which is the 100-year flow, and the scour check flood, which is the 200-year flow. Long-term bed elevation changes (degradation) are typically based on historical data at the bridge site. Bridge Inspection Reports do not exist at the Project, and long-term bed elevation change was not assessed for the i,p&lC pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Project. Based on the scour analysis for the design flood, the contraction scour depths range from 0 to 1.7 ft depending on support location, and the local scour depths range from 1.4 to 11.0 ft depending on the support location. The associated long-term scour elevation for the design flood ranges from 127.2 ft North American Vertical Datum of 1988 (NAVD 88) to 133.0 ft NAVD 88. Based on the scour analysis for the check flood, the contraction scour depths range from 0 to 2.1 ft depending on support location, and the local scour depths range from 2.1 to 13.0 ft depending on the support location. The associated long-term scour elevation for the check flood ranges from 126.9 to 133.0 ft NAVD 88. The foundations are required to be designed to withstand the effects of scour with pile resistance accounting for potential material loss due to scour. ii I June 25, 2026 Page 317 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Contents Executive Summary .......................................................................... 1 General Description................................................................. 1.1 Project Description........................................................ 1.2 Study Purpose............................................................... 1.3 Key Tasks...................................................................... 1.4 Design Criteria............................................................... 1.4.1 Hydraulic Design Criteria ................................. 1.4.2 Foundation Criteria ........................................... 1.4.3 Scour Design Criteria ....................................... 1.5 Vertical Datum............................................................... 2 Geographic Setting.................................................................. 2.1 Geographic Location ..................................................... 2.2 Watershed Description .................................................. 3 Hydrologic Assessment........................................................... 4 Hydraulic Analysis................................................................... 4.1 Design Tools................................................................. 4.2 Hydraulic Model Development ...................................... 4.2.1 Computational Grid/2D Flow Areas .................. 4.2.2 Model Boundary Conditions ............................. 4.2.3 Existing Condition Geometry ............................ 4.2.4 Proposed Condition Geometry Adjustments.... 4.3 Hydraulic Model Results ................................................ 4.3.1 Water Surface Elevations ................................. 4.3.2 Freeboard......................................................... 4.3.3 Flow Velocities ................................................. 5 Scour Analysis......................................................................... 5.1 Caltrans Bridge Inspection Reports .............................. 5.2 Existing Channel Bed .................................................... 5.3 Long -Term Bed Elevation Change ................................ 5.4 Contraction Scour.......................................................... 5.5 Pier Scour...................................................................... 5.6 Abutment Scour............................................................. 5.7 Total Scour.................................................................... 6 References.............................................................................. Tables Table 1. Watershed Drainage Areas ........................................................ Table 2. Hydrologic Data Summary for Project ........................................ Table 3. Data Sources Used to Develop the Hydraulic Model Geometry Table 4. Manning's n Values.................................................................... .1 .1 .1 .1 .7 .7 .8 .9 .9 10 10 10 13 15 15 15 15 15 17 21 23 26 36 37 40 40 41 41 41 42 43 44 47 11 13 17 20 Ju,feageoll pii9f 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 5. River Stations along San Luis Obispo Creek at Geographical Locations ..................................... 23 Table 6. 100-year Water Surface Elevations Upstream of Bridges............................................................ 34 Table 7. 50-year Water Surface Elevations Upstream of Bridges.............................................................. 34 Table 8. Hydrologic Summary Table for Prado Road West Overcrossing................................................. 35 Table 9. Hydrologic Summary Table for Prado Road East Overcrossing.................................................. 35 Table 10. Hydrologic Summary Table for US 101 NB Off-Ramp................................................................ 35 Table 11. Hydrologic Summary Table for US 101 NB On-Ramp................................................................ 36 Table 12. 100-Year Water Surface Elevations and Freeboard................................................................... 36 Table 13. 50-Year Water Surface Elevations and Freeboard..................................................................... 36 Table 14. Summary of Structures within Floodplain and Type of Scour Assessed .................................... 40 Table 15. Calculated Contraction Scour Depths.........................................................................................42 Table 16. Calculated Local Pier Scour Depths........................................................................................... 43 Table 17. Calculated Local Abutment (and MSE Wall) Scour Depths........................................................44 Table 18. Scour Summary Table: Prado Road West Overcrossing...........................................................44 Table 19. Scour Summary Table: Prado Road East Overcrossing............................................................44 Table 20. Scour Summary Table: US 101 NB Off-Ramp...........................................................................45 Table 21. Scour Summary Table: US 101 NB On-Ramp...........................................................................45 Table 22. Scour Data Table: Prado Road West Overcrossing................................................................... 45 Table 23. Scour Data Table: Prado Road East Overcrossing.................................................................... 45 Table 24. Scour Data Table: US 101 NB Off-Ramp...................................................................................46 Table 25. Scour Data Table: US 101 NB On-Ramp...................................................................................46 Figures Figure1. Project Location Map..................................................................................................................... 2 Figure2. Project Vicinity Map....................................................................................................................... 3 Figure 3. Proposed Prado Road Interchange Bridges General Plan............................................................4 Figure 4. Proposed US 101 NB Off -Ramp Bridge General Plan.................................................................. 5 Figure 5. Proposed US 101 NB On -Ramp Bridge General Plan.................................................................. 6 Figure 6. San Luis Obispo Creek Watershed Map..................................................................................... 11 Figure 7. Project Watershed Map............................................................................................................... 12 Figure 8. 2D Flow Areas and Boundary Conditions.................................................................................... 16 Figure 9. Bridges as SA/2D Connections in Hydraulic Model..................................................................... 19 Figure 10.Terrain Comparison in Vicinity of Project................................................................................... 22 Figure 11. Location of Profile Used to Summarize Model Results............................................................. 24 Figure 12. Locations of Cross Sections Used to Summarize Model Results ............................................. 25 Figure 13. Existing Condition 100-year Flow Depths.................................................................................. 26 Figure 14. Existing Condition 100-year Flow Depths at Project Vicinity ..................................................... 28 Figure 15. San Luis Obispo Creek 100-Year Water Surface Profile within Model Domain ........................29 Figure 16. San Luis Obispo Creek 50-Year Water Surface Profile within Model Domain .......................... 30 Figure 17. Changes in WSE within the 2D Model Domain......................................................................... 31 Figure 18. 100-year WSE Comparison (Proposed - Existing) within Project Vicinity ................................. 32 Figure 19. 50-year WSE Comparison (Proposed - Existing) within Project Vicinity ................................... 33 Figure 20. Changes in Velocities within the 2D Model Domain.................................................................. 38 Figure 21. 100-year Velocity Comparison (Proposed - Existing) within Project Vicinity ............................. 39 iv I June 25, 2026 Page 319 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 22. 50-year Velocity Comparison (Proposed - Existing) within Project Vicinity ............................... 39 Appendices Appendix A. FIS Excerpts Appendix B. HEC-RAS Model Results: Grid Extents View Appendix C. HEC-RAS Model Results: Project Vicinity View Appendix D. Scour Calculations Jlupeag,gaq pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Abbreviations 1 D one-dimensional 2D two-dimensional AASHTO American Association of State Highway and Transportation Officials AZ Arizona BDS Bridge Design Specifications BFE base flood elevation CA California Caltrans California Department of Transportation CFR Code of Federal Regulations cfs cubic feet per second City City of San Luis Obispo cm centimeter County County of San Luis Obispo CPT cone penetration test DDM Drainage Design Manual DEM Digital Elevation Model FEMA Federal Emergency Management Agency FHWA Federal Highway Administration FIRM Flood Insurance Rate Map FIS Flood Insurance Study ft feet, foot ft/s feet per second HDM Highway Design Manual HEC-18 Hydraulic Engineering Circular No. 18 HEC-RAS Hydrologic Engineering Center's River Analysis System LRFD Load and Resistance Factor Design m meter mi mile MSE mechanically stabilized earth NAVD 88 North American Vertical Datum of 1988 NB northbound NCHRP National Cooperative Highway Research Program NFIP National Flood Insurance Program OPR Original Product Resolution PG&E Pacific Gas and Electric PM Post Mile Project U.S. Route 101 (US 101) at Prado Road Interchange Project QL2 Quality Level 2 R9 Region 9 RS river station SA Storage Area US 101 U.S. Route 101 USACE United States Army Corps of Engineers USGS United States Geological Survey WSE water surface elevation vi I June 25, 2026 Page 321 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project This page is intentionally left blank. JunFftg-JA212vWf 1059 Page 323 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 1 General Description 1.1 Project Description The proposed U.S. Route 101 (US 101) at Prado Road Interchange Project (Project) includes improvements to extend Prado Road over US 101 to connect with Dalidio Drive, reconstruct the existing US 101 northbound (NB) off -ramp and on -ramp connections with Prado Road, and construct an auxiliary lane on NB US 101 between the Prado Road and Madonna Road interchanges in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the city of San Luis Obispo in the county of San Luis Obispo at Post Mile (PM) 26.8 and improvements on NB US 101 extend from PM 26.5 to PM 27.3. The preferred alternative includes a partial interchange with the proposed Prado Road overcrossing constructed over US 101, a new US 101 NB off -ramp to Prado Road, and a new NB on -ramp from Prado Road. The Project location map is shown in Figure 1. These bridges are shown in the Project vicinity map in Figure 2. 1.2 Study Purpose This Bridge Design Hydraulic Study focuses on the new bridges at the Prado Road overcrossing (west and east overcrossing bridges), US 101 NB off -ramp to Prado Road, and the US 101 NB on -ramp from Prado Road, which are located within the floodplain of San Luis Obispo Creek. The general plans for the proposed bridges are shown in Figure 3, Figure 4, and Figure 5. The purpose of this Bridge Design Hydraulic Study is to present the design flow characteristics for San Luis Obispo at the Project, the hydraulic characteristics associated with the pre -Project (existing condition) and post -Project (proposed condition), and the scour potential for the proposed condition. As part of a separate project, the Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0l07), which is located east of the proposed Project bridges, is proposed to be replaced. This Bridge Design Hydraulic Study incorporates data from the Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0107) replacement, but the bridge is not part of this study. 1.3 Key Tasks Key tasks performed in this study included: 1) a review of available hydrologic data, 2) a hydrologic analysis, 3) a hydraulic analysis to determine design water surface elevations (WSE) and flow velocities for the existing and proposed conditions, 4) and a scour analysis to estimate potential scour depths for the proposed condition. .lupeaggao- 4 ,pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 1. Project Location Map o` 1 El Chorro \ Regional Park Goldtree F �Os OsOs f L d// Fy Mine Hill San Luis Obispo �t',��✓ r Project Location San Luis Obispo County Regional if Airport �A VA Edna A. AA Ora ESRI. NASA, NGA, USGS, FEMA. SOURCES:,•t - ESRI. TOMTOM, GARMIN. FAO, NOAA. USGS. \`I \ • � � Tiber 11�l (C) OPENSTREETMAP CONTRIBUTORS. AND �,� THE GIs USER COMMUNITY �r •i��( Y ■ '� 1 l�f/ \ i �Y Source: Esri 2 1 June 25, 2026 Page 325 of 1059 rn LO 0 vl- - P, cl�b C2 d1' 7 c'•7 �C> N U a)O O u) cn I. d o 0 0 N c tm I ,, U- ■ rn LO 0 0 r` N (Y) N (B n fG ..b uo w Z b sc 6�on =., 0 z t y a p°pgg� s od = O OW a $1d� U w Z t7) � Z J a e U = t9 ^ 5 = o � z a 0 �r - 1 'P A ge N q tl U y, W r t � Fig � — l Al � L w a n e oc� p ' S — g c I ¢ � � b� �i�vuc•o S � Y C) m » D / o 00 q q _ D _ � C) m D 0 CY) q q _ D _ n Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 1.4 Design Criteria The following criteria were used in the design of the proposed bridges. 1.4.1 Hydraulic Design Criteria 1.4.1.1 Federal Highway Administration (FHWA) Standards Per Title 23 Chapter I Subchapter G Part 650 Subpart A Section 650.115 (23 Code of Federal Regulations [CFR] 650.115), "freeboard shall be provided, where practicable, to protect bridge structures from debris- and scour -related failure." (FHWA 2026). 1.4.1.2 Caltrans Standards From Memo to Designers 16-1 Hydraulic Design for Structures over Waterways, the proposed bridge soffit should provide adequate freeboard to pass anticipated drift for the 50-year design flood, or to pass the 100-year base flood without freeboard, whichever is greater (Caltrans 2017). From Chapter 820 of the Caltrans' Highway Design Manual (HDM), the criterion for the hydraulic design of bridges is that they be designed to pass the 2% probability of annual exceedance flow (50-year design discharge) with adequate freeboard to pass anticipated bedload and debris. Two (2) feet (ft) of freeboard is commonly used in bridge designs. Alternatively, the bridge can also be designed to pass the 1 % probability of annual exceedance flow (100-year design discharge, or base flood). No freeboard is added to the base flood (Caltrans 2025a). 1.4.1.3 County of San Luis Obispo Standards The Public Improvement Standards (San Luis Obispo County [County] Department of Public Works 2022) did not specify bridge freeboard criteria. However, the Public Improvement Standards does include a list of federal and state supplemental design standards, and includes a hierarchy to indicate which standards should take precedence. According to the Public Improvement Standards, "[i]f the County standard does not address the issue, then the appropriate State standard (Caltrans) governs. In cases where the County and State standards do not discuss the design issue, then the appropriate Federal standard governs." (San Luis Obispo County Department of Public Works 2022) 1.4.1.4 City of San Luis Obispo Standards The City of San Luis Obispo (City) developed a Waterway Management Plan comprised of three volumes, which discuss watershed management, management and maintenance for waterways in the San Luis Obispo Creek watershed, and policies for floodplain management with the City. The Waterway Management Plan also includes guidelines for designs of channels, storm drain systems, stormwater facilities, and erosion control, but does not specify bridge freeboard requirements. While bridge freeboard is not specified, the San Luis Obispo Creek Waterway Management Plan Volume III Drainage Design Manual (DDM) indicates that the San Luis Obispo Creek channel design requirement is for the 50-year flow in the reach from Madonna Road to Ju,P6W,ga09 pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Prado Road and 100-year flow in the reach from Prado Road to the confluence with Prefumo Creek (City of San Luis Obispo Department of Public Works and County of San Luis Obispo Flood Control District — Zone 9 2003). 1.4.1.5 Project Freeboard Criteria The City and County do not specify freeboard criteria for the hydraulic design of bridges. FHWA and Caltrans freeboard criteria are applicable to the Project: both of which require that bridges pass the 100-year design flow without additional freeboard, or the 50-year design flow with adequate freeboard to pass drift and debris (with 2 ft commonly used). The Project has been designed to meet FHWA and Caltrans freeboard criteria. 1.4.2 Foundation Criteria Bridges must be designed per the California Amendments to the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (BDS) (2017 Eighth Edition) (California Department of Transportation [Caltrans] 2019). The California Amendments to the AASHTO LRFD BDS (2017 Eighth Edition) Section 2.6.3 defers to state requirements for hydraulic studies. Per the California Amendments to the AASHTO LRFD BDS (2017 Eighth Edition) (Caltrans 2019), foundations should be designed to withstand the conditions of scour. Caltrans' Memo to Designers 16-1 (Caltrans 2017) provides additional guidance on foundation placement: The top of a spread footing must be placed at or below the anticipated total scour (Degradation + Contraction + Local) elevation (LRFD 2.6.4.4.2 and LRFD-BDS-CA Figure C2.6.4.4.2-1) unless founded on competent, scour -resistant bedrock. The top of a pile cap footing must be placed at or below the estimated degradation plus contraction scour depth (LRFD 2.6.4.4.2 and LRFD-BDS-CA Figure C2.6.4.4.2- 2). The bottom of a pile cap footing should be placed at or below the anticipated Total Scour elevation. (Caltrans 2017) Bridge Design Memo 10.7 (Caltrans 2025b) includes information pertaining to the design of driven piles used as deep foundations. According to AASHTO LRFD BDS, deep foundations "shall meet requirements for Service, Strength, Extreme Event." The pile foundations are required to be designed to withstand the effects of scour with pile resistance accounting for potential material loss due to scour. If the abutments are designed as piers, the foundations should be designed such that they are stable during the scour conditions, including loss of approach fill. This assumes an unsupported pile length above the total scour elevation. Structure Technical Policy 2.6 (STP 2.6) addresses design criteria for the hydraulic design and scour criteria for new bridges and bridge widenings over waterways (Caltrans 2025c). Similarly to Memo to Designers 16-1, STP 2.6 refers to BDS, but also requires that the foundations consider the check flood conditions based on frequencies up to the 200-year flood. Per STP 2.6, "[t]he design of piers shall ignore the presence and function of scour countermeasures, and the streambed material above the scour elevation is 8 1 June 25, 2026 Page 331 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project assumed to have been removed." The following requirements apply to the deep foundations at the piers and abutments: Piers supported on pile groups shall be located so that the bottom of the pile cap is below the scour elevation determined for the Scour Design Flood and shall satisfy the Extreme Event II limit state for scour conditions determined for the Scour (Design) Check Flood. For abutments supported on deep foundations, the presence and function of scour countermeasures shall not be considered, and the streambed material above the scour elevation is assumed to have been removed (except as noted below). The foundations shall be located so that the bottom of the pile cap is below the scour elevation determined for the Scour Design Flood and shall satisfy the Extreme Event II limit state for scour conditions determined for the Scour (Design) Check Flood. However, the abutment foundation may be designed assuming the soil protected by the scour countermeasure remains in place under all limit states, except the Extreme Event II limit state for the Scour (Design) Check Flood, if the following criteria are satisfied: • The current or projected annualized average daily traffic (AADT) multiplied by the detour length is less than or equal to 10,000 vehicle -miles, and the AADT is less than or equal to 2000 vehicles. The detour route shall not include scour - critical bridges. • The scour countermeasure is properly designed as described in HEC-23 and TechBrief FHWA-HIF-23-048 (Caltrans 2025c) The exception for abutment foundation design does not apply to the Project site because the AADT exceeds the value noted and scour countermeasures are not proposed for the Project. 1.4.3 Scour Design Criteria The evaluation of potential scour at the proposed bridge followed the criteria described in the FHWA's Hydraulic Engineering Circular No. 18 (HEC-18), "Evaluating Scour at Bridges" (FHWA 2012). The evaluation of potential scour was based on the hydraulic characteristics of the scour design flood, which is the 100-year design discharge. Per STP 2.6, scour was also evaluated for the check flood, which is the 200-year design discharge. The total scour was estimated based upon the cumulative effects of the long- term bed elevation change, general (contraction) scour, and local scour. 1.5 Vertical Datum The Project references the North American Vertical Datum of 1988 (NAVD 88). J„Peag,Qao? epf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 2 Geographic Setting 2.1 Geographic Location The intersection of Dalidio Drive with Froom Ranch Way at the western limits of the Project is at 35015'30.44" North latitude and 120°40'36.14" West longitude (Google Earth 2025). The intersection of Prado Road with South Higuera Street at the eastern limits of the Project is at 35'15'16.62" North latitude and 120°40'8.42" West longitude (Google Earth 2025). The Project bridges are located within the San Luis Obispo Creek floodplain within the city of San Luis Obispo. The Project bridges are at the intersection of Prado Road with US 101. The Prado Road bridge over the San Luis Obispo Creek (Existing Bridge Number 49C0107) bridge crossing is located east of the proposed Project bridges. 2.2 Watershed Description The Project site is within the San Luis Obispo Creek watershed. The San Luis Obispo Creek watershed is approximately 84-square miles (mi) and located within the Estero Bay Hydrologic Unit, Point Buchon Hydrologic Area, and San Luis Obispo Creek sub- area. The upstream limits are in the Santa Lucia Range northeast of San Luis Obispo. The San Luis Obispo Creek generally flows southwest and discharges into the Pacific Ocean at Avila Beach. Prefumo Creek and Froom Creek are tributaries to San Luis Obispo Creek downstream of the Project location. The Project site is located approximately 50 ft from San Luis Obispo Creek in the floodplain where surface water flows from San Luis Obispo Creek toward Prefumo Creek located approximately 0.25 mi west of the Project site. See Figure 6 for a map of the San Luis Obispo Creek watershed. The watershed drainage areas for San Luis Obispo Creek, Prefumo Creek, and Froom Creek are shown in Table 1 and the associated watershed delineations are shown in Figure 7. These Project watersheds are associated with the flows at the upstream boundary conditions used in the hydraulic model; the flows are discussed later in Section 3 and the hydraulic model is discussed later in Section 4. The San Luis Obispo Creek watershed area associated with Prado Road is also shown in Figure 7. 10 1 June 25, 2026 Page 333 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 6. San Luis Obispo Creek Watershed Map Mid Salinas River - Atascadero Morro Bay Area Watershed Watershed San Lui Obi San Luis Arroyo Grande Obispo Project Creek Watershed Creek Location Prefumo Creek Froom Creek San L is Obispo Cree atershed Coastal Irish Hills Watershed Pismo Creek A,,-; each Watershed N \ California State Parks, Esn, HERE Garmin, SafeGraph, 0 1.25 2.5 5 Miles \ METI/NASA, USGS, Bureau of Land Management, EPA, F''-- ,, Beach NIPS, USDA l i i i l i i i l —1 Data Source: Watersheds — County Department of Public Works (2014); Creeks — HDR (2019a) Table 1. Watershed Drainage Areas San Luis Obispo Creek At intersection of Marsh Street and Archer Street At Prado Road Prefumo Creek Upstream of confluence of San Luis Obispo Creek Froom Creek Upstream of confluence of San Luis Obispo Creek Source: United States Geological Survey (USGS) 2026a 24.7 14.2 1.7 Jung 2j�A pf 1059 LL Qi �Q' C.� J O O: L N N d �L N` m d it V N L d N m m 6 ¢ (v U, y m U O ma a-:!:- p m aG m y m O a m m D a Y N o U J Oa m L Oa m O u E N (n N L U E o `p d n` a R U) En E 00 O c c t2 Go°r Cr--�� d c_ zs N N W O NN W NU a, C O� FO 10 mY z� Zz Z2 u 2 f 0.0 4 i, ~ W W N K � p F N a =a N D Tm� O C c �f � y R W UZ 2- QQ Zz OLL iZ U�z zw� y0� ,U z U'm � W LO1 N z W 2a.^ KNz Z'a l Rio ccw, q�m WwK z wy0 w I "t �Qf yQ� W � y uzz W o w , Q( Ozy Q w O N >U = oz� v i 0 m0z O p jmO- z C i az Z' yiw pa0 O _« D.2 o=o O N 0 N V 04 N O N V W N L 0 U) rn LO 0 vl- - 0 M co N M n r Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 3 Hydrologic Assessment The streams that were assessed for the Project include San Luis Obispo Creek, Prefumo Creek, and Froom Creek. Peak flows for San Luis Obispo Creek and Prefumo Creek were obtained from the Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS); however, the FIS did not include peak flows at Froom Creek. The peak flows at Froom Creek were calculated using the USGS regional regression (flood -frequency) equations. The flood -frequency equations were developed by the USGS and based on analysis of data from gage stations. California is divided into six regions. These flood -frequency equations are generally used to estimate stream flow for ungaged sites that are not affected by substantial urban development and that are natural (unregulated) streams. On July 18, 2012, USGS issued Methods for Determining Magnitude and Frequency of Floods in California, Based on Data through Water Year 2006 (Gotvald et al. 2012), which contains updated regional flood -frequency equations, and revised the boundaries of the six unique regions within California. These equations are based on annual peak -flow data through water year 2006 for 771 streamflow-gaging stations in California with 10 or more years of data. The updated equations were used in support of the hydrologic analysis of Froom Creek. Basin characteristics for the Froom Creek watershed at US 101 (just upstream of its confluence with San Luis Obispo Creek) were obtained from StreamStats (USGS 2026a). The drainage area of Froom Creek at US 101 is 1.7 square mi (see Section 2.1) and the mean annual precipitation is 21.2 inches (USGS 2026a). See Table 2, which presents the calculated 50-year, 100-year, and 200-year flows for Froom Creek. Table 2. Hydrologic Data Summary for Project San Luis At intersection of Marsh FIS 10,300 13,500 17,040 Obispo Creek Street and Archer Street Prefumo Upstream of confluence FIS 2,400 3,100 3,930 Creek of San Luis Obispo Creek Froom Creek Upstream of confluence USGS 278 358 445 of San Luis Obispo Creek Note: the 100-year and 50-year flows were taken directly from the FIS for San Luis Obispo Creek and Prefumo Creek. The 200-year flows were extrapolated based on the ratios of the FEMA to regional regression estimates and using the extrapolated ratio to estimate a FEMA 200-year flow. FEMA is the nationwide administrator of the National Flood Insurance Program (NFIP). As part of the NFIP, typically, each participating county (or community) has a FIS, which is used to locally develop Flood Insurance Rate Maps (FIRM) and base flood elevations (BFE). The FIS for San Luis Obispo County, California and Incorporated Areas included peak flows along San Luis Obispo Creek and Prefumo Creek for the 100-year, 50-year, and 10-year return periods. The FIS included multiple flow change locations along the creeks (excerpts from the FIS are included in Appendix A); the intersection of Marsh Street and Archer Street is located upstream/north of the Project site approximately at June A�61:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project M the upstream boundary of the two-dimensional (21D) model domain (see Section 4 for additional details related to the hydraulic model). The 10-year, 50-year, 100-year, and 200-year flows for San Luis Obispo Creek and Prefumo Creek were also calculated using the USGS regional regression equations. The ratios of the flows listed in the FEMA FIS and the USGS regional regression estimates for the 10-year, 50-year, and 100-year flows were used to extrapolate a ratio for the 200- year flow, and the ratio was multiplied by the USGS regional regression estimate for the 200-year flow to estimate an extrapolated 200-year FEMA flow for the two streams. Table 2 presents the 100-year and 50-year peak flows from the FIS for San Luis Obispo - and Prefumo creeks (FEMA 2024) and the extrapolated 200-year flows for the two streams. 14 1 June 25, 2026 Page 337 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4 Hydraulic Analysis The following sections discuss the development of the hydraulic models and summarize the results for the existing and proposed conditions. The model results are included in Appendix B and Appendix C. 4.1 Design Tools The hydraulic analyses were performed for the existing and proposed conditions using the United States Army Corps of Engineers' (USACE) Hydrologic Engineering Center's River Analysis System (HEC-RAS) modeling software, Version 6.6 (USACE 2024). 4.2 Hydraulic Model Development A 2D model was developed for the Project to assess the existing and proposed conditions. The following sections describe the parameters used in the hydraulic model development. The hydraulic modeling utilized the 2D hydraulic model that was developed as part of the Floodplain Evaluation Report from the previous phase of the Project (HDR 2023) as the base model. The model was refined to include updated information as available and to incorporate additional detailed Project improvement details. 4.2.1 Computational Grid/21D Flow Areas The Project was modeled using a single 2D flow area in the vicinity of the Project (see Figure 8). The 2D mesh was used in the hydraulic model to encompass San Luis Obispo Creek as well as the Prefumo Creek tributary and Froom Creek tributary, both of which contribute flows to San Luis Obispo Creek. The mesh in the 2D hydraulic model has an average cell size of 50 ft and included a total of 54,568 cells that are the same in both the existing and proposed conditions model geometries. Refinements to the computational grid were made by placing breaklines and refinement regions as needed to provide added definition in controlling flow direction through the creeks, around roads, piers, approach ramps, and abutments for the Project, which are modeled in the terrain. The computational points and breaklines were copied from the proposed condition geometry to the existing condition geometry so that both geometries have the same computational grid to minimize the impacts of model differences on the results. 4.2.2 Model Boundary Conditions Boundary conditions of the 2D mesh areas were placed at the upstream and downstream ends of the channels where flows could enter and exit the model during the simulated flows. Figure 8 shows the 2D flow area cells included in the mesh of the model domain as well as the upstream and downstream boundary condition locations. The model has three upstream boundary conditions and one downstream boundary condition. June A2Agf 1059 co N D O Q 0 OU co J � C C 7 co 0 cn m O N U +� � } L) o U d Q L, -0 o co a) o 0 Q CN m z 0 co fn C Q O tf N C: O 0 UU O 21' E-o am 1 co m C O C 0.0 Q U O OU U) L, co J � C c � c n m rn LO 0 vl- - 0 rn M co N O1 M n Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.2.3 4.2.3.1 San Luis Obispo Creek has an upstream boundary approximately 220 ft upstream of the Pacific Gas and Electric (PG&E) access bridge near Lower Marsh Street. The upstream boundary for Prefumo Creek is at the downstream face of the Madonna Road bridge. Froom Creek has an upstream boundary in the foothills southwest of Los Osos Valley Road at approximately 275 ft NAVD 88. Both Prefumo Creek and Froom Creek are tributaries to San Luis Obispo Creek. The upstream boundary conditions were set to constant inflow values equal to the peak flows (see Table 2 in Section 3 for a summary of the peak flows) at the respective creek locations. The downstream boundary of the model is on San Luis Obispo Creek approximately 1,800 ft downstream of the Los Osos Valley Road over San Luis Obispo Creek bridge. The downstream boundary condition was set to a slope of 0.006 ft/ft, which was measured from the Original Product Resolution (OPR) Digital Elevation Model (DEM) (USGS 2018) along the boundary edge of the model domain. Existing Condition Geometry The geometries for the hydraulic model were developed using a combination of the following data sources listed in Table 3. Table 3. Data Sources Used to Develop the Hydraulic Model Geometry Short Description Source of D. 1 OPR California (CA) Arizona (AZ) FEMA Region 9 (R9) lidar 2017 2 Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0107) 3 Project topography based on aerial mapping with survey conforms 4 Topography with newly added digital terrain model in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road 5 Prefumo Creek 6 Froom Ranch development 7 Project grading for approaches and Elks Lane 8 Project linework for abutments, MSE walls, and piers USGS Wallace Group Wallace Group Wallace Group HDR HDR Consor Engineers Consor Engineers The data sources listed in Table 3 from USGS, Wallace Group, and HDR (numbers 1 through 6) were used to develop the existing condition hydraulic model and as a basis for the proposed condition hydraulic model. The proposed condition incorporated the proposed Project improvements based on the data sources listed in Table 3 that were provided by Consor Engineers (numbers 7 and 8). These data sources are described in greater detail in Section 4.2.3. Terrain The terrain for the existing condition hydraulic model utilized the data sources from USGS, Wallace Group, and HDR (see Table 3). June AJQpf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project According to the "CA AZ FEMA R9 2017 D18 Airborne Lidar Report" (USGS 2019), the OPR DEM encompasses areas within California and Arizona; the target resolution of the OPR DEM for the portion of the data within California was Quality Level 2 (QL2) with 2 points per square meter and 0.7-meter (m) nominal point spacing. QL2 lidar has a vertical accuracy of 10 centimeters (cm) and a DEM cell size of 1 m. The OPR DEM (USGS 2018) terrain was imported into HEC-RAS using the function in the RAS Mapper tool built-in to HEC-RAS (USACE 2024). The following Project -specific terrain sources from Wallace Group, and HDR were used to supplement the OPR DEM (USGS 2018). The Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0l07), which is located east of the proposed Project bridges is proposed to be replaced as a part of a separate project. The terrain for San Luis Obispo Creek in the vicinity of Prado Road at Existing Bridge Number 49C0107 included the existing terrain incorporated with the proposed improvements for the Prado Road bridge over San Luis Obispo Creek bridge replacement project, and was provided to the Project team (Wallace Group 2025a). This bridge is assumed to be replaced prior to the Project, and was modeled as a storage area (SA)/2D connection using data from the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). Topography was developed for the Project based on aerial mapping with areas of survey conforms and augmentation from ground surveys (Wallace Group 2025b), which encompasses the areas of improvement within the Project limits. Additional topography with newly added digital terrain model was used to supplement the area in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road (Wallace Group 2025c), which is in an area west of US 101 and west of the Project improvements. Cross sections from Prefumo Creek were converted to a 2D surface using survey data that was used to develop the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023), to encompass the area of Prefumo Creek at its confluence with San Luis Obispo Creek, which is located south of the Project improvements. The Froom Ranch development is located west of the agricultural portion of the San Luis Ranch, and the terrain that encompasses that area was clipped from a terrain that was used in the development of the 2-Dimensional Hydraulic Model Update Draft Report (HDR 2019b). The existing merged terrain within the model domain is shown in Figure 9. 4.2.3.2 Bridges Existing bridges were modeled as SA/2D connections as described in the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). The structures are shown in Figure 9. 18 1 June 25, 2026 Page 341 of 1059 7 m D vl- � CIA � oz ,} /° ^^w S / \ 0 CU 2 77 • - o }/ 3 / c ^ �/ kE R� \ ƒ -0 qca $ k $ ____-� _ 2 mo E§ / \ o nm 29 R \ $ C 3 o E .v f CL7 E 2 2 ± / § q \k �� J E ■ § k Z2 E � ®co \ a o a) a F 2 U } § cu E2 U m E § _ o ƒ ± q L CO§ / §E 5 / § § § © ■ E U E 2 \ ■ ■ o U ƒ FD d 3 & q 2 0- R \ / 2 E b a.q \ Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 4.2.3.3 Manning's Roughness Coefficients Manning's roughness coefficients (n values) were used in the hydraulic model to estimate energy losses in the flow due to friction. Table 4 lists the Manning's n values that were used to represent land cover conditions within the hydraulic model domain. Manning's n values were selected based upon standard documented values of similar stream conditions from aerial imagery; common channel types are extensively researched in Open -Channel Hydraulics (Chow, V.T. 1959) and have been compiled in the HEC-RAS River Analysis System, Hydraulic Reference Manual (USACE 2016). The Manning's n value used to represent the areas surrounding the fences were based on engineering judgement, with the assumption that debris would accumulate along the fence line and significantly impact the conveyance across the fence line. Manning's n values for the areas of San Luis Obispo Creek, Prefumo Creek, and Froom Creek are based on values established in the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). The Manning's n value used for the area in the agricultural portion of the San Luis Ranch (described as "Ag Hoop Houses") was based on a floodplain value that considered obstructions and vegetation estimated following Cowan's procedure (USACE 2016). Table 4. Manning's n Values Description Manning's n Description Minor Stream - Clean, Winding, Asphalt 0.016 Some Rock 0.04 Minor Stream - Some Weeds and Open Water 0.03 Stones 0.04 Urban Area 0.04 Pasture - No Brush 0.025 Urban -Parking Lot Area 0.04 Pasture - Short Grass 0.03 Urban -Cemetery 0.04 Pasture - High Grass 0.04 Urban Planned Development 0.08 Cultivated Area - No Crop 0.03 Urban -Open Grass Areas 0.05 Cultivated Area - Mature Row Crop 0.035 Urban -Cemetery - Short Grass 0.035 Cultivated Area - Mature Field Crop 0.045 Brush - Scattered Brush, Heavy Chain link Fence 9 Weeds 0.05 SLO Creek — one-dimensional (1 D) Brush - Light Brush and Trees, in model 0.065 Summer 0.07 Prefumo Creek - 1 D model 0.07 Heavy Stands of Timber and Brush 0.1 Froom Creek - 1 D model 0.04 Asphalt - Smooth 0.013 Ag Hoop Houses 0.28 20 1 June 25, 2026 Page 343 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.2.4 Proposed Condition Geometry Adjustments The existing condition hydraulic model geometry was used as a basis for the proposed condition hydraulic model. The following adjustments were incorporated in the proposed condition geometry to represent the Project improvements. 4.2.4.1 Terrain The existing condition merged terrain described in Section 4.2.3 was used as the base terrain for the proposed condition terrain. Additional modifications were made to the base terrain using the data sources listed in Table 3 that were provided by Consor Engineers (numbers 7 and 8) to account for the proposed Project improvements. The grading for roadway approaches for the Project bridges and Elks Lane realignment were updated based on information provided by Consor Engineers (Consor Engineers 2025). The piers, abutments, and mechanically stabilized earth (MSE) walls that support the Project bridges (Figure 3, Figure 4, and Figure 5) were imported into the HEC-RAS hydraulic model based on information provided by Consor Engineers (Consor Engineers 2026e) and the elevations were modeled using terrain modifications to be above the 100-year WSE. See the top image in Figure 10 for an enlarged version of the existing condition merged terrain, which is zoomed in (as compared to the terrain in Figure 9 that shows the terrain within the model domain) to better discern the changes to the terrain in the proposed condition. The terrain in the areas beyond the visible areas in Figure 10 are the same in both the existing and proposed condition geometries. See the bottom image in Figure 10 for the proposed condition merged terrain. 4.2.4.2 Bridges The bridges included in the existing condition geometry remained the same in the proposed condition geometry (Figure 9). Elements of the Project bridges that would be within contact with the evaluated flows were modeled using terrain modifications to represent the piers, abutments, and MSE walls. The bridge superstructures would be elevated above the 100-year WSE and were not included in the model. 4.2.4.3 Manning's Roughness Coefficients The same values were used in both the existing and proposed conditions models except in the areas in the vicinity of the proposed Project bridges where the existing at -grade US 101 ramps and Prado Road subgrade would be removed. The Project is proposing landscaping in the areas where the subgrade will be removed, and the Manning's n values were set to 0.04 in the proposed condition. JunPAggA142iof 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 10.Terrain Comparison in Vicinity of Project Existing Terrain (top image) s �J J � \J J\v + Proposed Terrain (bottom image) s J 101 22 1 June 25, 2026 Page 345 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.3 Hydraulic Model Results As previously stated in Section 4.2.2, the hydraulic models were computed using constant flow values at the upstream boundaries and a normal depth at the downstream boundary. San Luis Obispo Creek flows in a southerly direction within the model domain. The model simulations were run for a period long enough for the model results to stabilize to a steady state, which was confirmed by result hydrographs from various locations throughout the model. The hydraulic model results are reported at the final timestep of the model simulations. The hydraulic model results are presented in this section as detailed maps of the 2D HEC-RAS results and as tables and graphs extracted from the 2D results using a profile along San Luis Obispo Creek (see Figure 11, which shows the profile line) and cross section lines (see locations of cut lines in Figure 12, which were cut along the upstream faces of the bridges). The profile line follows the channel alignment along San Luis Obispo Creek through the model domain. The downstream limit of the model domain is at approximately 0 ft and the upstream limit of the model domain is at approximately 17,500 ft measured along the profile line of San Luis Obispo Creek. These main channel distance measurements will be referred to as river stations (RS) in this study, and the RS decreases numerically in the downstream direction. For reference, a few geographical features in the Project vicinity and within the model domain are identified in Table 5. Table 5. River Stations along San Luis Obispo Creek at Geographical Locations 16,900 Intersection of Marsh Street and Archer Street 13,600 Madonna Road 8,360 Prado Road 2,150 Confluence with Prefumo Creek 1,765 Los Osos Valley Road 1,050 Confluence with Froom Creek The cross section lines were chosen to be parallel to the bridges and to represent the locations upstream of the bridges. References to the profile line and cross section lines are made in the following hydraulic model results summary in Section 4.3. Additional detailed hydraulic model results are available in Appendix B (showing the results within the extents of the model) and Appendix C (showing the results within the Project vicinity). June AJ61:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 11. Location of Profile Used to Summarize Model Results LEGEND Proposed Project Mft I Sources: USACE 2024 and Consor Engineers 2026a (with 2D model boundary, San Luis Obispo Creek profile, and notes from HDR) 24 1 June 25, 2026 Page 347 of 1059 o � U O. J 0 w ^p w o m o 0- ._ ° N d U) l6 V D. J N N J O co d O a cn U U ZI r y W 3 � I I � W J LL ,r f r 0 rn LO 0 0 00 Nt (Y) Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 4.3.1 Water Surface Elevations The results of the hydraulic models indicate that flows spill out of the banks of San Luis Obispo Creek upstream of the Project area until approximately RS 10,500 where the modeled flows are contained within the San Luis Obispo Creek channel. Prado Road is located approximately at RS 8,360. The spill flows occur in the 100-year and 50-year events and is an existing condition that is perpetuated in the proposed condition (see Figure 13, which shows the 100-year flow depths in the existing condition; Appendix B and Appendix C include additional results for the 50-year flow and for the proposed condition). Figure 14 shows the 100-year flow depths in the existing condition, which is a larger scale version of Figure 13 to show greater detail in the Project vicinity. As shown in Figure 14, the 100-year and 50-year flows are contained within San Luis Obispo Creek in the reach starting from RS 10,500 and downstream past Prado Road within the limits of the model domain. Figure 13. Existing Condition 100-year Flow Depths LEGEND Proposed PrniPrt 2D Model D, San Luis Ot 01JAN20000200 00 2000 R I e14 6 5 6 3 2 t 0 Sources: USACE 2024 and Consor Engineers 2026a (with 2D model boundary, San Luis Obispo Creek profile, depth raster, and notes from HDR) 26 1 June 25, 2026 Page 349 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project The water surface profiles along the San Luis Obispo Creek profile line are shown in Figure 15, which compares the 100-year water surface profiles in the existing and proposed condition, and Figure 16, which compares the 50-year water surface profiles in the existing and proposed condition. Figure 15 and Figure 16 show insignificant changes in WSEs along the San Luis Obispo Creek profile. Comparison rasters were also generated in HEC-RAS to calculate the difference in WSEs between the proposed and existing conditions. A comparison of the WSEs within the model domain are shown in Figure 17 for the 100-year and 50-year storm events. Figure 18 and Figure 19 show larger scale versions of Figure 17 to show greater detail in the Project vicinity. In general, the comparisons in WSEs show insignificant changes along San Luis Obispo Creek; the model shows increases in WSE that are 0.2 ft or less (or decreases in WSE) within the model domain. There are localized increases and decreases in WSE within the vicinity of the Project improvements. During the 100-year storm event, the maximum increase in the WSE is 2.4 ft, and it occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in WSE is 1.9 ft, and it also occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. WSEs were also extracted along the cross section lines shown in Figure 12 along the upstream faces of the bridges. The maximum WSEs along those lines are shown in Table 6 for the 100-year storm and Table 7 for the 50-year storm. Based on a comparison of the WSEs extracted along the respective cross section lines, the maximum WSE in the proposed condition compared with the maximum WSE in the existing condition increases by 0.1 ft or less. The average WSEs along those lines are also shown in Table 6 for the 100-year storm and Table 7 for the 50-year storm. Based on a comparison of the WSEs extracted along the respective cross section lines, the average WSE in the proposed condition compared with the average WSE in the existing condition increases by 0.3 ft or less. JunP AgQ2pf 1059 � U O Ua U U 7 U1 m c o c° T _r_ 2 L N C N -0 N D o a)ry O)o a-o m m d C (6 �U) a N t Q G 3 _0 L d � O O N L U V o o U _ �_ O F U) U) 0 7 •� 0- 7 J W o 0 CU 0 d N Cl) Z W " Lu T J U- M— i rn LO 0 vl- - 0 LO co N 0) M n Y E 0 L O co L Q O Q Y N N L U 0 0_ O J C L f6 O N O N i N N c c w O O U C f0 N O N W co Q N N fA C (D � : — 0 U) N T U 3 O � d U 3 a) fu C 70 Co T L 2 i c � o� c o � � o a> ry U' o �a m �6 d m c Eo �U) d� LL O O a0 � CO _M N_ O N (99 CIAVN 11) UOIJeA@13 O O O CR O O O 0 0 0 0 o O U co ..+ O O C CD 0 0 0 0 O N O O W 0 c W U) as 0 _O a a) U) 0 0_ 0 i rn LO 0 vl- - Q CIT ur CIA oz Y�1 LL O CD CD Cl)N O 07 (99 CIAVN 11) uOIJena13 0 0 0 0 0 0 W U) m a� o T 0 0 o LO a a� 0 0_ 0 L a o .� I o O U c0 W L O co O T OCT U o LO c 0) co c C N X W O I O O O O O O N O O co rn LO 0 vl- - 0 M LO cM N 0) M 0- T U 3 O � d U : N fu C 70 Co T L 2 i c � of c � o ary l a o a m �6 �a m c Eo d� pp 3.- ccer� Y e C \ O to `� �L cu E O � \\ L 8 1 Ar j 1 O �L cu Q O U w U) L cu (D C) CD rn LO 0 4- a CIA Lo- A 0 cn ii U `—' Q W � Cl) m c N a � _5 c c d ❑o O a) of O O)O r O � .Z n d : LL 8.097 a ' 1; rn LO 0 vl- - 0 LO co N 0) M 0- cm N O N Li N N c N M �soss�s S LL ry 0 O (0 W U) 0 c N O Q Y 'U 0 a D) O J c f6 U) L O w c O U c N O N W U Q U) Z) Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 6. 100-year Water Surface Elevations Upstream of Bridges WSE (ft NA VD 88) Change in WSE (ft NA VD 88) Change in WSE (ft) WSE (ft) Existing Proposed (Proposed Existing Proposed (Proposed -Existing) -Existing) Prado Road West 136.9 136.9 0 133.7 133.9 0.2 Overcrossing Prado Road East 137.3 137.4 0.1 137.3 137.4 0.1 Overcrossing ■ US 101 NB Off -Ramp 136.8 136.5 -0.3 136.3 136.2 -0.1 US 101 NB On -Ramp 137.5 137.E � 137.4 137.5 0.1 Table 7. 50-year Water Surface Elevations Upstream of Bridges WSE (ft NA VD 88) Change in WSE (ft NA VD 88) Change in WSE (ft) WSE (ft) Existing Proposed (Proposed Existing Proposed (Proposed -Existing) -Existing) Prado Road West 136.6 136.7 0.1 133.2 133.5 0.3 Overcrossing Prado Road East 136.9 136.9 0 136.9 136.9 0 Overcrossing US 101 NB Off -Ramp 136.5 136.2 -0.3 136.1 135.9 -0.2 US 101 NB On -Ramp 137.0 137.1 0.1 137.0 137.0 0 According to Memo to Designers 16-1 (Caltrans 2017), a hydrologic summary table shall be placed on the Project Foundation Plan. The hydrologic summary is shown in Table 8 for the proposed Prado Road west overcrossing, Table 9 for the proposed Prado Road east overcrossing, Table 10 for the proposed US 101 NB off -ramp to Prado Road, and Table 11 for the proposed US 101 NB on -ramp from Prado Road. The reported WSEs are based on the upstream cross section at the proposed respective bridges. The WSE varies along the cross sections, and the reported value is the maximum at each of the bridge locations. 34 1 June 25, 2026 Page 357 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Table 8. Hydrologic Summary Table for Prado Road West Overcrossing Discharge 2,330 3,470 4,510 Water Surface Elevation at 136.7 136.9 137.2 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. Table 9. Hydrologic Summary Table for Prado Road East Overcrossing Frequency ii Discharge 1,600 2,610 3,630 Water Surface Elevation at 136.9 137.4 137.8 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. Table 10. Hydrologic Summary Table for US 101 NB Off -Ramp Hydrologic 50-year 100-year Vischarge,.00 Water Surface Elevation at 136.2 136.5 136.7 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. JunPAg839f 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 11. Hydrologic Summary Table for US 101 NB On -Ramp Discharge 1,600 2,610 3,630 Water Surface Elevation at 137.1 137.6 138.1 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. 4.3.2 Freeboard As described in Section 1.4, the hydraulic design criteria applicable to the Project require that bridges pass the 100-year design flow without freeboard and the 50-year flow with 2 ft of freeboard from the lowest portion of the bridge span. The WSEs and available freeboard are presented in Table 12 for the 100-year storm and Table 13 for the 50-year storm. The minimum soffit elevations are based on the bridge general plans (Consor Engineers 2026b, 2026c, and 2026d). The soffit elevations account for the depth of the proposed girders but do not incorporate the roadway cross slope. Based on the results of the hydraulic modeling, the bridges would provide applicable freeboard during the 100- year and 50-year flows. Table 12. 100-Year Water Surface Elevations and Freeboard Prado Road West Overcrossing 142.7 Prado Road East Overcrossing 139.4 US 101 NB Off -Ramp 144.4 US 101 NB On -Ramp 144.4 136.9 137.4 I 136.5 137.6 Table 13. 50-Year Water Surface Elevations and Freeboard Prado Road West Overcrossing 142.71 Prado Road East Overcrossing 139.37 US 101 NB Off -Ramp 144.42 US 101 NB On -Ramp 144.42 136.7 136.9 136.2 137.1 5.8 7.9 M MMI 2.5 8.2 7.3 36 1 June 25, 2026 Page 359 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.3.3 Flow Velocities Comparison rasters were generated in HEC-RAS to calculate the difference in velocities between the proposed and existing conditions. A comparison of the velocities within the model domain are shown in Figure 20 for the 100-year and 50-year storm events. Figure 21 and Figure 22 show larger scale versions of Figure 20 to show greater detail in the Project vicinity. In general, the comparisons in velocities show insignificant changes along San Luis Obispo Creek; the model shows the increases in velocities are 0.2 ft per second (ft/s) or less (or that there are decreases in velocities) within the model domain. There are localized increases in velocities within the vicinity of the Project improvements. During the 100-year storm event, the maximum increase in velocity is 4.9 ft/s, and it occurs at the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in velocity is 4.7 ft/s, and it also occurs at the western abutment (Abut 1) at the Prado Road west overcrossing bridge. JunP Aq(l Pf 1059 E O 0 O 0 N d t C t .N d O d Im c t U N d L CD E o 0 0 n E 0 U �U O L co Lo 8 �iE!- 8 QQ8 � � BaNs$S Q I�oo9.7 v JS 1p 't 0 N \ Q C \ U U N C) O 0') LO 0 vl- - 0 co N M 0- Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 21. 100-year Velocity Comparison (Proposed - Existing) within Project Vicinity . Se1x,W.'CggraVN o,a/Cf � n,nTooa oamoo 00 1 :-.0 At - Sources: USACE 2024 and Consor Engineers 2026a (with San Luis Obispo Creek profile, and velocity raster from HDR) Figure 22. 50-year Velocity Comparison (Proposed - Existing) within Project Vicinity Ok Sources: USACE 2024 and Consor Engineers 2026a (with San Luis Obispo Creek profile, and velocity raster from HDR) JunPAg2apf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 5 Scour Analysis HDR evaluated bridge scour per the criteria described in "Evaluating Scour at Bridges" (FHWA 2012). HDR evaluated the scour potential using the results of the proposed condition 2D hydraulic model analysis from HEC-RAS for the 100-year design storm as the scour design flood and the 200-year design storm as the scour (design) check flood (see Section 4.3 for the hydraulic model results) and the soil properties at the Project site from the geotechnical studies (see Section 5.2 for a summary of the existing channel bed characteristics). The calculations were performed for the Project bridges (US 101 NB off - ramp to Prado Road, US 101 NB on -ramp from Prado Road, and the Prado Road overcrossing) that will be located within the San Luis Obispo Creek floodplain. The Prado Road west and east overcrossing structures comprise the Prado Road overcrossing. The US 101 NB off -ramp and US 101 NB on -ramp intersect Prado Road in the area between the west and east overcrossing structures. The abutments in the area of the intersection of Prado Road with the US 101 off- and on -ramps are enclosed by MSE walls. The abutment scour equations were used to estimate the scour at the MSE walls (Table 14). Table 14. Summary of Structures within Floodplain and Type of Scour Assessed Prado Road West Abut 1 (at BB end) NCHRP abutment Overcrossing Bent 2 L_.M Bent 3 Pier Abut 4 (at EB end) NCHRP abutment (enclosed by MSE Wall) Prado Road East Abut 1 (at BB end) NCHRP abutment Overcrossing (enclosed by MSE Wall) Bent 2 Pier - Abut 3 (at EB end) NCHRP abutment US 101 NB Off -Ramp to Abut 1 (at BB end) NCHRP abutment Prado Road Bent 2 Pier Abut 3 (at EB end) NCHRP abutment (enclosed by MSE Wall) US 101 NB On -Ramp from Abut 1 (at BB end) NCHRP abutment Prado Road (enclosed by MSE Wall) Bent 2 Pier Abut 3 (at EB end) NCHRP abutment The following sub -sections summarize the results of the scour analysis. 5.1 Caltrans Bridge Inspection Reports Bridge Inspection Reports do not exist because the Project is proposing new structures. 40 1 June 25, 2026 Page 363 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 5.2 Existing Channel Bed Under the existing conditions, the locations of the proposed structures are currently impervious. As part of the Project, the pavement subgrade will be removed, and will be pervious, which would be susceptible to scour. According to the Draft Structure Preliminary Geotechnical Report Bridges for the Project (Yeh and Associates, Inc. 2025), the regional geology at the proposed Project bridges is young alluvial floodplain deposits. The Draft Structure Preliminary Geotechnical Report Bridges also describes the subsurface conditions at the Project, which were based on cone penetration tests (CPT) soundings, which showed surficial units of existing artificial fill and alluvium (Qya); in the area of the proposed Project bridges, the ground surface underlying the existing fill was predominantly younger alluvium (Qya) with the Qyal subunit generally in the upper zone compared to the Qya2 subunit (Yeh and Associates, Inc. 2025). The Qyal subunit consisted of "predominantly soft to hard clay and sandy clay..." and the Qya2 subunit consisted of "predominantly soft to medium stiff clay..." (Yeh and Associates, Inc. 2025). Based on borings in the vicinity of the Project bridges, the soil classifications at the proposed supports are flat clay (CH) and lean clay (CL). Based on these soil classifications, the channel bed in the floodplain areas underlying the proposed foundations was considered to be cohesive for the purpose of analyzing scour. 5.3 Long -Term Bed Elevation Change Long-term bed elevation changes (degradation) are typically based on historical data at the bridge site. As previously stated in Section 5.1, Bridge Inspection Reports do not exist at the Project, and long-term bed elevation change was not assessed at the Project. 5.4 Contraction Scour Contraction scour occurs when the flow area of a stream is reduced by: 1) the natural contraction of the stream channel; 2) a bridge structure; 3) the overbank flow forced back to the channel, 4) natural stream constrictions, or 5) long highway approaches to the bridge over the floodplain. From the continuity equation, a decrease in flow area results in an increase in average velocity and bed shear stress through the contraction. Hence, there is an increase in erosive forces in the contraction section, and more bed material is removed from the contracted reach than is transported into the reach. This increase in transport of bed material from the reach lowers the natural bed elevation. As the bed elevation is lowered, the flow area increases. Thus, the velocity and shear stress decrease until relative equilibrium is reached (i.e., the quantity of bed material that is transported into the reach is equal to that removed from the reach, or the bed shear stress is decreased to a value such that no sediment is transported out of the reach). Contraction scour, in a natural channel or at a bridge crossing, involves removal of material from the bed across all or most of the channel width (FHWA 2012). There are two conditions for contraction scour: clear -water or live -bed. Clear -water contraction scour occurs when the bed material is not in motion in the flow upstream of the bridge crossing. Clear -water conditions are typical in floodplain overbank areas such as at the Project site. JunPAg4tipf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project As previously stated in Section 5.2, the channel bed in the floodplain was considered to be cohesive for the purpose of analyzing scour. Equation 6.6 from HEC-18 was used to calculate contraction scour for cohesive materials for the bridge supports (FHWA 2012). A summary of the calculated contraction scour depths is included in Table 15 and the detailed calculations are included in Appendix D. Table 15. Calculated Contraction Scour Depths Structure Name m i Contraction Scour Depth ii ii Flood)(Scour Design (Scoul; ll ..• Prado Road West Abut 1 (at BB end) 1.7 - Overcrossing Bent 2 1.4 ■ Bent 3 0.9 Abut 4 (at EB end) 1.2 . (enclosed by MSE Wall) Prado Road East Abut 1 (at BB end) 1 2 Overcrossing (enclosed by MSE Wall) Bent 2 0.8 1.� Abut 3 (at EB end) 0.7 1 US 101 NB Off -Ramp Abut 1 (at BB end) 1.1 1. to Prado Road Bent 2 1.1 1.3 Abut 3 (at EB end) 1.2 1.2 (enclosed by MSE Wall) US 101 NB On -Ramp Abut 1 (at BB end) from Prado Road (enclosed by MSE Wall) 1.2 1.2 Bent 2 0 0.0 Abut 3 (at EB end) 0.9 1.3 5.5 Pier Scour Pier scour is caused by vortices (known as a horseshoe vortex) forming at the base of the pier. The horseshoe vortex results from the pileup of water on the upstream surface of the pier and subsequent acceleration of the flow around the base of the pier. The scour depth at a pier is influenced by pier design (shape and dimension), flow characteristics (flow rate, local velocity, and depth at the pier), and sediment particle size distribution. As previously stated in Section 5.2, the channel bed in the floodplain was considered to be cohesive for the purpose of analyzing scour. Equation 7.35 from HEC- 42 1 June 25, 2026 Page 365 of 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 18 was used to calculate pier scour for cohesive materials (FHWA 2012). The pier scour calculation assumes the footings will not be exposed to flow. A summary of the calculated local pier scour depths is included in Table 16 and the detailed calculations are included in Appendix D. Table 16. Calculated Local Pier Scour Depths Prado Road West Overcrossing Prado Road East Overcrossing US 101 NB Off -Ramp to Prado Road US 101 NB On -Ramp from Prado Road Bent 2 5.9 6.7 Bent 2 Bent 2 Bent 2 5.6 Abutment Scour 4.7 5.9 Mon"Empp- all 2.7 Abutment scour occurs when the bridge abutments and roadway embankments block approaching flow. A vortex is formed at the upstream end of the abutment and along the toe of the abutment due to the flow obstruction caused by the abutments. The highly turbulent flow caused by the abutments generates the erosive shear action and subsequently causes scouring. According to HEC-18 (FHWA, 2012), local scour at bridge abutments is commonly evaluated using either the Froehlich or HIRE live -bed scour equations. The National Cooperative Highway Research Program (NCHRP) developed alternative abutment scour equations based on a range of abutment types, locations, flow conditions, and sediment transport conditions. While the Froehlich, HIRE, and NCHRP equations are acceptable methods that can be used to estimate scour at abutments, the NCHRP equations have several advantages. Unlike the Froehlich and HIRE equations, the NCHRP equations do not use an effective embankment length, which can be difficult to determine. The NCHRP equations are also considered to be more representative of the physical scouring processes at the abutments. Because of these reasons, the NCHRP method was used to estimate scour at the abutments. The NCHRP method calculates a scour depth that includes both local and contraction scour components at the abutment. The NCHRP scour was calculated using the equations presented in Section 8.6.3 of HEC-18 (FHWA 2012). The contraction scour depth calculated in Section 5.4 of this report was subtracted from the calculated scour depth to determine the local abutment scour. Some of the abutments are proposed to be enclosed by MSE walls, and the NCHRP equation was also used to estimate the local scour at the MSE walls. A summary of the calculated local scour depths for the abutments and MSE walls is included in Table 17 and the detailed calculations are included in Appendix D. JunPAgAAq6t:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 17. Calculated Local Abutment (and MSE Wall) Scour Depths Prado Road West Abut 1 (at BB end) li� Overcrossing Abut 4 (at EB end) MOE MM (enclosed by MSE Wall) Prado Road East Overcrossing Abut 1 BB end) (enclosed by MSE Wall) 1 Abut 3 (at EB end) 1.= 2.9 US 101 NB Off -Ramp Abut 1 (at BB end) 4.8 to Prado Road Abut 3 (at EB end) 1.4 2.1 (enclosed by MSE Wall) US 101 NB On -Ramp Abut 1 (at BB end) 1.7 2.8 from Prado Road (enclosed by MSE Wall) Abut 3 (at EB end) 5.6 7.7 5.7 Total Scour Total scour is the sum of the long-term bed elevation change (degradation scour), contraction scour, and local scour (see Table 18 through Table 21 for the scour depths for the proposed bridges based on the scour design flood estimates). Table 18. Scour Summary Table: Prado Road West Overcrossing Abut 1 N/A 1.7 6.2 Bent 2 N/A 1.4 5.9 Bent 3 N/A 0.9 11.0 Abut 4 N/A 1.2 1.7 Table 19. Scour Summary Table: Prado Road East Overcrossing Abut 1 N/A 1.2 1.4 Bent 2 N/A 0.8 4.7 Abut 3 N/A 0.7 1.6 44 1 June 25, 2026 Page 367 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Table 20. Scour Summary Table: US 101 NB Off -Ramp Abut 1 N/A 1.1 4.8 Bent 2 Abut 3 N/A 1.2 1.4 Table 21. Scour Summary Table: US 101 NB On -Ramp Abut 1 N/A 1.2 1.7 Bent 2 N/A 0.0 I Abut 3 N/A 0.9 5.6 According to Memo to Designers 16-1 (Caltrans 2017), a scour data table shall be placed on the Project Foundation Plan. The scour data tables (see Table 22 through Table 25) for the Project present the long-term scour elevations (based upon the long-term bed degradation and contraction scour depths) and the short-term scour depths (based upon the local scour depth). The long-term scour elevations reference the finish grade elevations at the supports. Table 22. Scour Data Table: Prado Road West Overcrossing Abut 1 127.8 6.2 Bent 2 127.2 5.9 Bent 3 130.9 11.0 131.8 1.7 Table 23. Scour Data Table: Prado Road East Overcrossing Abut 1 131.8 1.4 Bent 2 132.2 4.7 Abut 3 132.3 1.6 June Ag8tPf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 24. Scour Data Table: US 101 NB Off -Ramp Abut 1 131.9 4.8 1r3ent 2 11M 5.6 Abut 3 131.8 1.4 Table 25. Scour Data Table: US 101 NB On -Ramp Abut 1 131.8 1.7 �i3.0 2.0 Abut 3 132.1 5.6 46 1 June 25, 2026 Page 369 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 6 References California Department of Transportation (Caltrans) 2014 Design Information Bulletin No 87-01. (DIB 87-01). "Hybrid Streambank Revetments: Vegetated Rock Slope Protection." Accessed February 4, 2026. https://dot.ca.gov/- /media/dot-media/programs/design/documents/dib87-01.pdf. 2017 Memo to Designers 16-1 Hydraulic Design for Structures over Waterways. Accessed February 4, 2026. htti)s://dot.ca.gov/-/media/dot- media/programs/engineering/documents/memotodesigner/f0006651-mtd-16-1-final.pdf. 2019 California Amendments to the AASHTO LRFD Bridge Design Specifications (2017 Eighth Edition). Accessed February 4, 2026. https://dot.ca.gov/programs/engineering- services/manuals/aashto-Irfd-ca-amendments. 2025a "Chapter 820: Cross Drainage" in Highway Design Manual. Accessed February 16, 2026. https://dot.ca.gov/-/med ia/dot-media/programs/design/documents/chp0820--a l l ypdf. 2025b Bridge Design Memo 10.7. 10.7 Piles and Shafts." Accessed October 30, 2025. https://dot.ca.gov/-/media/dot- media/programs/engineering/documents/brid edq�esignmemos/10/202506bdml007pilesa ndshafts-al 1 y.pdf. 2025c Structure Technical Policy 2.6. "2.6 Hydraulic Design for Structures over Waterways." Accessed June 8, 2026. https://dot.ca.gov/-/media/dot- med is/programs/engi neering/documents/structure-technical-policy/section-2/sto-26- hydraulic-design-for-structures-over-waterways-121025-a11 y.pdf. Chow, V.T. 1959 Open -Channel Hydraulics. New York: McGraw-Hill Book Co. City of San Luis Obispo Department of Public Works and County of San Luis Obispo Flood Control District — Zone 9 2003 Drainage Design Manual. Volume III. Accessed February 4, 2026. htti)s://www.slocity.org/home/showr)ublisheddocument/4400/638121531708370000. Consor Engineers 2025 Prado IC_Surfaces for HDR_20251023.dwg. [Project grading for approaches and Elks Lane] 2026a Prado Plan.dwg [Proposed roadway linework] 2026b D218721a-a-gp01-General Plan.pdf. [Prado Overcrossing Bridge General Plan] 2026c D218721b-a-gp01-OFF-Ramp GP.pdf. [US 101 NB Off -Ramp Bridge General Plan] 2026d D218721c-a-gp01-ON-Ramp GP.pdf. [US 101 NB On -Ramp Bridge General Plan] 2026e D218721—BRIDGE-PLAN.dwg. [Project linework for abutments, MSE walls, and piers] Federal Emergency Management Agency (FEMA) 2024 Flood Insurance Study. San Luis Obispo County, California and Incorporated Areas. Flood Insurance Study Number 06079CV001 D. Version Number 2.6.3.6. Effective Date: June 6, 2024. Accessed February 4, 2026. https://msc.fema.gov/portal/downloadProduct?productTyl)elD=FINAL PRODUCT&produ ctSubTypelD=FIS REPORT&productlD=06079CV001 D. Federal Highway Administration (FHWA) 2012 "Evaluating Scour at Bridges." Hydraulic Engineering Circular No. 18. Fifth Edition. Publication No. FHWA-HIF-12-03. JunP A71(�pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 2026 Title 23 Chapter I Subchapter G Part 650. "Bridges, Structures, and Hydraulics" Subpart A Section 650.115. Accessed February 16, 2026. https://www.ecfr.gov/current/title- 23/chapter-1/subchapter-G/part-650. Google Earth 2025 Google Earth Pro 7.3.6.10441. Gotvald, A.J., N.A. Barth, A.G. Veilleux, and C. Parrett 2012 Methods for determining magnitude and frequency of floods in California, based on data through water year 2006. United States Geological Survey Scientific Investigations Report 2012-5113. Accessed January 8, 2026. http://pubs.usgs.gov/sir/2012/5113. HDR 2019a 2-Dimensional Hydraulic Model Update Draft Report. 2019b EC_wP8_08.02.2019.tif. [Existing condition terrain used in development of 2- Dimensional Hydraulic Model Update Draft Report] 2023 Floodplain Evaluation Report. Prado Road Overcrossing Project On U.S. 101 05-SLO- 101-PM 26.5-27.3. San Luis Obispo County Department of Public Works 2014 SLO County Watersheds. (Computer file). Accessed July 20, 2023. https://www.slocounty.ca.gov/Departments/Public-Works/Forms- Documents/Projects/SLO-Watershed-Project/Resources/SLO-Cou nty-Watersheds- 1 .as x. 2022 Public Improvement Standards. Accessed February 4, 2026. https://www.slocounty.ca.gov/departments/public-works/forms-documents/development- services/public-improvements/public-improvement-standards/countypublic- i m p rove m e n t-standards-2022. United States Army Corps of Engineers (USACE) 2016 HEC-RAS River Analysis System, Hydraulic Reference Manual, Version 5.0. CPD-69. 2024 Hydrologic Engineering Center's River Analysis System (HEC-RAS) [Modeling software] Version 6.6. Accessed February 4, 2026. https://github.com/HydrologicEngineeringCenter/hec- downloads/releases/download/l .0.33/HEC-RAS_66_Setup.exe. United States Geological Survey (USGS) 2019 "CA AZ FEMA R9 2017 D18 Airborne Lidar Report." Contract # G16PC00022. Task Order # 140G0218F0027. Contractor Woolpert. Project # 78262. Accessed February 6, 2026. https://prd- tnm.s3.amazonaws.com/StagedProducts/Elevation/metadata/CA AZ FEMA R9 Lidar 2017 D18/CA FEMA Z4 B2 2018/reports/CA AZ FEMA R9 Lidar 2017 D18 Lidar ProjectReport.pdf. 2018 "USGS Original Project Resolution CA_AZ_FEMA_R9—Lidar_2017_D18 60521606." Accessed February 6, 2026. https://www.sciencebase.gov/catalog/item/60491 clfd34ebl20311 ac439. 2026a StreamStats. Accessed February 4, 2026. https://streamstats.usgs.gov/ss/. 2026b National Hydrography Dataset. Accessed February 11, 2026. httr)s://www.usgs.gov/national-hvdrographv/national-hvdrographv-dataset. 48 1 June 25, 2026 Page 371 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Wallace Group 2025a 0061-0077 DSGN-Creek Grading.dwg. [San Luis Obispo Creek surface associated with the separate proposed bridge replacement at Existing Bridge Number 49C01071. 2025b 5-1H640 US 101 and Prado Road - TOPO.dwg. [Project topography based on aerial mapping with survey conforms]. 2025c 5-1H640 US 101 and Prado Road - TOPO_091525.dwg. [Topography with newly added digital terrain model in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road]. Yeh and Associates, Inc. 2025 Draft Structure Preliminary Geotechnical Report Bridges. US 101 and Prado Road Interchange Project. San Luis Obispo, California. 05-SLO-101-PM 26.5-27.3. Caltrans Project No. 113-0000-0405; EA 05-1 H640. City Specification No. 2091613-02. Yeh Project No.: 223-400. JunPAggA7124pf 1059 Page 373 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Appendix A. FIS Excerpts PAgp2�742pf 1059 FLOOD INSURANCE STUDY VOLUME 1 OF 4 SAN LUIS OBISPO COUNTY, CALIFORNIA AND INCORPORATED AREAS MMUNITY NAME COMMUNITY UMBERS ARROYO GRANDE, CITY OF 060305 ATASCADERO, CITY OF 060700 EL PASO DE ROBLES, CITY OF 060308 GROVER BEACH, CITY OF 060306 _MORRO BAY, CITY OF _PISMO BEACH, CITY OF SAN LUIS OBISPO, CITY OF SAN LUIS OBISPO COUNTY, UNINCORPORATED AREAS Q�CA R 1'.41, FEMA \� SEGJ REVISED: JUNE 6, 2024 FLOOD INSURANCE STUDY NUMBER 06079CV001 D Version Number 2.6.3.6 060307 060309 060310 060304 Page 375 of 1059 U O O O O O O O O000 O O O O C) O N mO co I— O � (14 O 00 O In O O C Q () T T T 00 It N T � LO LO C,4 co M LO co O M N � N N C U L CC: Q � 7 o U LL T O O C: C) C) C) C) CD 0') U") CD0 C) O C) C)C) O C) O C) O C) O C) C) CD C) U") N U") r 00 N ti d7 T O O O Q •X 00 I� O N N TLO coT coM CV T a� o U W T N T U O � (.) 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M L U) 0 'm L U) U lm L U) 0 lm L U) U lm L U) U lm L U) U 'm L U) 0 LO LO rn 0 0 ti ti cM N M a_ d 7 C O U N a t v N B 4- 0 m E E N d B m H a) o�� 0 0 0 0 � 0 0 0 N C O CO M T (M O O N 00 co CY) p Q U T T 00 T (14 T CY) M 00 N 1- m � a) N C U L < m Q � 7 -x � + + + o U LL T m a) (..) C O O It It O LO O O O 00 v C :- Q m U) O 00 O CO M 00 00 M 00 00 00M � O � O O M O P- (M LO a) o U W T 0) N N T U D Y � U O O N N ti O O O O O m C: C Q m O O O 00 LO T LO T O �� LO 00 00 LO 00 LO O N O 00 M O U (.0Ln M M CD d7 T N U �C: Q � o U c Q m 0 U') 0 � « 0 00 LO co T o T 0 0') 0 0') M I co I C oU T N N e') N N e') N N m N 0 N N N a7 co 7 EQ�� ) T T « * co N N N T T T T co O N coO I co ` > m m � O m O m _ O N '� 4) T a) "O O Y Cn a) E Y m Cn a) L L m O O >+ O 0 7 C O .- 0 c o m 2 E� ��_ �Y O Ov c� m m Q0 C >, o N 2i �' 2' mm U N a� U m U m E m 6 Q p) °m U U) O 0 C O Y C (.0 O�v0 N L N 7 7 O c c U C mW OLO O E X�D o Ya)m 7 T -C O 0 00 U a M Q ( QNLm L U 2 O nOTQ — O� U J O 5 Q U JQ� . . QQ —� m a) 0- o_ Z m U)> Q Q �Q Q Q L Q� U L O O Q O Q O QQ� O � � � �Q O O 'O cn U O o __ U oLL U O ° E E O O O O a) O 0) cn O U) Q 5Ei VJ > O OOO 0v 0/ 0/ VJ 0 J Y J Y J Y J Y J Y m Y m Y m Y m Y m Y m Y m Y U Y O O a) a) a) a) a) a) a) () a) a) () a) () O a) m L a) m L () m L a) m L a) m L a) m L a) m L a) m L a) m L a) m L a) m L a) m L a) L E (n U (n U (n 0 (n U (n 0 U) U U) U (n 0 U) U U) U U) U (n 0 (n 0 CD LO rn 0 O 00 ti cM N cB a_ Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Appendix B. HEC-RAS Model Results: Grid Figure B 1. Figure B 2. Figure B 3. Figure B 4. Figure B 5. Figure B 6. Figure B 7. Figure B 8. Extents View Depth (ft) at 100-year Flow Depth (ft) at 50-year Flow Velocity (ft/s) at 100-year Flow Velocity (ft/s) at 50-year Flow Water Surface Elevation (ft NAVD 88) at 100-year Flow Water Surface Elevation (ft NAVD 88) at 50-year Flow Comparison of Velocity and Water Surface Elevation at 100-year Flow Comparison of Velocity and Water Surface Elevation at 50-year Flow June 25, 2026 Page 379 of 1059 rn LO 0 0 0 00 (Y) (B cI O U N 0 n� S C C% _ A :1 rn LO 0 O 00 (Y) N (B m m D 0 q 00 q _ D _ 0- rn LO 0 O c+') 00 (Y) N (B rn LO 0 0 It 00 (Y) m LO 0 O LO 00 (Y) N cB 0 c U -o N 0 Z cl IL n rn LO 0 0 cO 00 (Y) m to I O 10L O .2d O 11 N HE �c O U 0 06 m`� m L Eo 7 —y M a� LL IF. �aos�s tib'rvh'�`O' m LO 0 O ti 00 a� cB n Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Appendix C. HEC-RAS Model Results: Project Vicinity View Figure C 1. Depth (ft) at 100-year Flow Figure C 2. Depth (ft) at 50-year Flow Figure C 3. Velocity (ft/s) at 100-year Flow Figure C 4. Velocity (ft/s) at 50-year Flow Figure C 5. Water Surface Elevation (ft NAVD 88) at 100-year Flow Figure C 6. Water Surface Elevation (ft NAVD 88) at 50-year Flow Figure C 7. Comparison of Velocity and Water Surface Elevation at 100-year Flow Figure C 8. Comparison of Velocity and Water Surface Elevation at 50-year Flow Figure C 9. Proposed Condition Depth (ft) at 200-year Flow Figure C 10. Proposed Condition Velocity (ft/s) at 200-year Flow PAgp2�$&pf 1059 Preliminary Bridge Design Hydraulic Study F�� US 101 at Prado Road Interchange Project r Figure C-1. Depth (ft) at 100-year Flow Existing Condition Proposed Condition w.rt'E.rw� wt r«. tins. �E z iC .. or,uvommm m Page 389 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-2. Depth (ft) at 50-year Flow Existing Condition .A \ s.rew •e..rq�e r•,• r �r.m ttarItauuaaoom-m m w- Proposed Condition '� ,,.n.i,.� ii.,.nw r i.�M.m tnpr tlJMG0Y0m-mm �r as+rteMille r Page 390 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project r Figure C-3. Velocity (ft/s) at 100-year Flow Existing Condition 1..IFm" Vb* rae W Proposed Condition .. ad..& Tr i F � ---- .u�Focmmmm Page 391 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-4. Velocity (ft/s) at 50-year Flow Existing Condition . 1�YL'W"E �ia�ly SO Y�ilY11V o1JA100W W 00 00 j t . k � Proposed Condition � H SMKW Tropa��pywrEW� MIAsJ OIL1gpm W-OOm jo k � � ~i Page 392 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project r Figure C-5. Water Surface Elevation (ft NAVD 88) at 100-year Flow Existing Condition s.�.r t.�.�.y im r..rrY.mrar• ouunmommm 1 v Proposed Condition ,1�V100„YEIY� ... OIIAM)000 OJ 00 o0 Page 393 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-6. Water Surface Elevation (ft NAVD 88) at 50-year Flow Existing Condition 9tlq.1M 'FUWy60yW RMrOW9' o1,ANJmO o]0000 I r w Proposed Condition s.rew 'PgpNSGrY HYrOM9' 0„Aw)000m 00 m t 'r I Page 394 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study F�� US 101 at Prado Road Interchange Project r Figure C-7. Comparison of Velocity and Water Surface Elevation at 100-year Flow Velocity (ft/s) Comparison � � MMc,d YAry�INM_ O1J111OEW W-00 ro �1 i .r A AMkre Water Surface Elevation (ft NAVD 88) Comparison sr.r.,.e ro.q.,.waE .m,x auuoomm-m m • ti i+ � ' r r ; tl, Page 395 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-8. Comparison of Velocity and Water Surface Elevation at 50-year Flow Velocity (ft(s) Comparison �a A 1 Water Surface Elevation (ft NAVD 88) Comparison mU,onmmm mi Page 396 of 1059 June 25, 2026 Figure C-9. Proposed Condition Depth (ft) at 200-year Flow Preliminary Bridge Design Hydraulic Study L�� US 101 at Prado Road Interchange Project r Figure C-10. Proposed Condition Velocity (ft/s) at 200-year Flow Page 397 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Appendix D. Scour Calculations June 25, 2026 Page 398 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) Structure Name Support Contraction Scour Depth (ft) 200-year 100-year Prado Road West Overcrossing Abut 1(at BB end) 2.1 1.7 Bent 2 1.7 1.4 Bent 3 1.4 0.9 Abut 4 (at EB end) (enclosed by MSE Wall) 1.2 1.2 Prado Road East Overcrossing Abut 1(at BB end) (enclosed by MSE Wall) 1.2 1.2 Bent 2 1.1 0.8 Abut 3 (at EB end) 1.0 0.7 US 101 NB Off -Ramp to Prado Road Abut 1(at BB end) 1.3 1.1 Bent 2 1.3 1.1 Abut 3 (at EB end) (enclosed by MSE Wall) 1.2 1.2 US 101 NB On -Ramp From Prado Road Abut 1(at BB end) (enclosed by MSE Wall) 1.2 1.2 Bent 2 0.0 0.0 Abut 3 (at EB end) 1.3 0.9 Structure Name Support Local Scour Depth (ft) 200-year 100-year Prado Road West Overcrossing Abut 1(at BB end) 7.8 6.2 Bent 2 6.7 5.9 Bent 3 13.0 11.0 Abut 4 (at EB end) (enclosed by MSE Wall) 2.8 1.7 Prado Road East Overcrossing Abut 1(at BB end) (enclosed by MSE Wall) 2.1 1.4 Bent 2 5.9 4.7 Abut 3 (at EB end) 2.9 1.6 US 101 NB Off -Ramp to Prado Road Abut 1(at BB end) 5.8 4.8 Bent 2 6.4 5.6 Abut 3 (at EB end) (enclosed by MSE Wall) 2.1 1.4 US 101 NB On -Ramp from Prado Road Abut 1(at BB end) (enclosed by MSE Wall) 2.8 1.7 Bent 2 2.7 2.0 Abut 3 (at EB end) 7.7 5.6 Page 399 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) 100-year Scour Sum maryTables Scour Data Tables Prado West Overcrossing, Bridge No. 49C#### Prado West Overcrossing, Bridge No. 49C#### Short Term (Local)a MMMM Long Term (Degradation andShort Term ft) Scour Depth (ft) Contraction) lft) ur Elevation Scour Der Bent 3 1 Bent 3 130.91 Prado East Overcrossing, Bridge No. 49C#### Prado East Overcrossing, Bridge No. 49C#### Support Degradation M No. Scour Depth (ft) Scour Depth (ft) Short Term Contraction) (Sftj ur Elevation Scour Der a Bent 2 N/A 1 Abut 3 N/A 1 US 101 NB • • Bridge No.49 #### US 101• 1 Bridge No. Short Term (Local)Short EMMM Term ft) Scour Depth (ft) No. Contraction) (Sftj ur Elevation Scour Der Abut 1 1 Abut US 101 NB • • Bridge No. 49 #### US 101: • • Bridge No. 49 Support Degradation Contraction Short Term (Local) No. Scour Depth (ft) Scour Depth (ft) Scour Depth (ft) Support Long Term (Degradation and Short Term No. Contraction) (Sftj ur Elevation Scour Der Bent 2 N/A 0.0 2.0 Bent 2 133.0 2.0 Abut 3 N/A 0.9 Page 400 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge Prado Road West Overcrossing Support Abut 1 Bent 2 Bent 3 Equation 6.7: a = YV2n�2 Yo-1/3 I( KU Variable Value Unit Description g 62.4 62.4 62.4 Ib/ftA3 unit weight of water (62.4 Ib/ftA3 and 9800 N/mA3) VZ 4.3 3.6 2.9 ft/s average velocity in contracted section n 0.04 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.2 2.2 1.5 ft Upstream flow depth is 1.3 1.3 1.3 N/MA2=Pa lCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (�3VZ " p Ys-.It = 0.94y1 - / 9Y1 1 3 gny Variable Value Unit Description y1 0.7 0.7 0.5 m Upstream average flow depth Vz 1.3 1.1 0.9 m/s Average velocity in contracted section K, 1 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 1000 kg/mA3 Density of water g 9.81 9.81 9.81 m/sA2 acceleration due to gravity y, pit 0.5 0.4 0.3 m Ultimate contraction scour ys pit 1.7 1 1.4 1 0.9 Ift Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 1 Page 401 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge Prado Road East Overcrossing Support Bent 2 Abut 3 Equation 6.7: a = Y �V�n�2 Yo-i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.0 1.8 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K, 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Yo 3.1 3.5 ft Upstream flow depth T 1 1.3 1.3 N/m^2=Pa lCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83V2 p Ys—utr = 0.94y1 — / 9Yl gnyl a Variable Value Unit Description Y, 1.0 1.1 m Upstream average flow depth VZ 0.6 0.5 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for 5.1. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity Ys .ic 1 0.2 0.2 1 m Ultimate contraction scour Ys we 1 0.8 0.7 Ift I Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 2 Page 402 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB Off Ramp Support Abut 1 Bent 2 Equation 6.7: a = YV2n�2 Yo-1/3 I( KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4lb/ftA3 and 9800 N/mA3) VZ 3.0 2.6 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.0 2.8 ft Upstream flow depth is 1.3 1.3 N/mA2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc (�3VZ " p Ys—.It = 0.94y1 — / 9Y1 1 3 gny Variable Value Unit Description y1 0.6 0.9 m Upstream average flow depth Vz 0.9 0.8 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/mA3 Density of water g 9.81 9.81 m/sA2 acceleration due to gravity y, sic 1 0.3 0.3 m Ultimate contraction scour Ys we ft JUltimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 3 Page 403 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB On Ramp Support Bent 2 Abut 3 Equation 6.7: a = Y �V�n�2 Yo-i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 0.4 2.0 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K, 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Yo 2.2 4.2 ft Upstream flow depth T 1 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83V2 p Ys—utr = 0.94y1 — / 9Yl gnyl a Variable Value Unit Description Y, 0.7 1.3 m Upstream average flow depth VZ 0.1 0.6 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity Ys .ic 1 0.0 0.3 m Ultimate contraction scour Ys we 1 0.0 1 0.9 ift Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 4 Page 404 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge MSE Walls Support Intersection of Prado Rd with US 101 Ramps Equation 6.7: T = Y V2n2 YD-1/3 (K,) Variable Value Unit Description g 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.4 ft/s average velocity in contracted section n 0.04 Manning's roughness coefficient K, 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 4.8 ft Upstream flow depth T, 1.3 N/m^2=Pa Critical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (�3VZ " p Ys—.It = 0.94y1 — / 9Y1 1 3 gny Variable Value Unit Description y1 1.5 m Upstream average flow depth Vz 0.7 m/s Average velocity in contracted section K, 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 kg/m^3 Density of water g 9.81 m/s^2 acceleration due to gravity ys 1 0.4 m Ultimate contraction scour y� ui, 11.2 Ift I Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 5 Page 405 of 1059 FYZ US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: vl� ) Ys = 2.2K1KZa0.65 2.6V1 — VC 0.7 Variable Value Unit Description Bridge Prado Road West Overcrossing Support Bent 2 Bent 3 # of Columns 3 3 a 5 5 ft Pier width L 15 15 ft Pier length L/a 3 3 If L/a is larger than 12, then use 12 as a maximum 6 0 30 degrees Angle of attack of flow Group of cylinders Group of cylinders Pier shape K1 1 1 Correction factor for pier shape K2 1.0 1.8 Correction factor for angle of attack V1 2.6 2.8 ft/s Approach velocity Vc 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 ft/sA2 ys 5.9 11.0 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 6 Page 406 of 1059 FYZ US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K11CZa0.65 2.6y1—V, 0.7 Variable Value Unit Description Bridge Prado Road East Overcrossin US 101 NB Off Ramp US 101 NB On Ramp Support Bent 2 Bent 2 Bent 2 # of Columns 4 2 2 a 5 4 4 ft Pier width L 20 8 8 ft Pier length L/a 4 2 2 If L/a is larger than 12, then use 12 as a maximum e 0 0 0 degrees Angle of attack of flow Group of cylinders Group of cylinders Group of cylinders Pier shape K1 1 1 1 Correction factor for pier shape K2 1.0 1.0 1.0 Correction factor for angle of attack V1 2.1 2.9 1.2 ft/s Approach velocity Vc 0.5 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 1 5.6 32.2 ft/sA2 1 2.0 ft YS1 4.7 Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 7 Page 407 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition Prado Road West Overcrossing Units = (Metric or English) Right Overbank = Abutment 1 (West) y1= Upstream flow depth Upstream velocity Upstream flow Upstream channel width q1 = Upstream unit discharge Flow depth through bridge Velocity through bridge Flow through bridge Bridge opening width less pier widths q2 = Unit discharge in the constricted opening Abutment scour equation = Alternative Clear -Water Condition Abutment Scour Yc — (T') 3/7 ( Ku% ff t, = Critical shear stress for the floodplain material n = Manning n of the floodplain material under the bridge y = Unit weight of water Ku = 1.486 English units, 1.0 SI units yc = Flow depth including contraction scour Ymax = aAYc or Ymax = aaYc Ys = Ymax — Yo yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. English 2.2 ft 2.5 ft/s 2802.0 cfs 552.4 ft 5.5 ft2/s 2.6 ft 4.3 ft/s 2968.7 cfs 409.5 ft 11.4 ft2/s Alternative Clear -Water Equation 8.7 0.112 lb/ft-2 0.040 62.4 Ib/ftA3 1.486 5.5 Ift Equation 8.3 Equation 8.4 5.5 2.1 Wingwall 1.93 10.5 2.6 7.9 1.7 6.2 hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 8 Page 408 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition Prado Road East Overcrossing Units = (Metric or English) English Left Overbank = Abutment 3 (East) y1= Upstream flow depth 3.5 ft Upstream velocity 2.2 ft/s Upstream flow 2416.9 cfs Upstream channel width 210.1 ft q1 = Upstream unit discharge 7.6 ft2/s Flow depth through bridge 3.3 ft Velocity through bridge 1.8 ft/s Flow through bridge 1530.2 cfs Bridge opening width less pier widths 261.1 ft q2 = Unit discharge in the constricted opening 5.8 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 15.6 Ift Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.6 0.8 Wingwall 1.00 5.6 3.3 2.3 0.7 1.6 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 9 Page 409 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition US 101 NB Off Ramp Units = (Metric or English) English Left Overbank = Abutment 1 (South) y1= Upstream flow depth 2.0 ft Upstream velocity 2.3 ft/s Upstream flow 1514.1 cfs Upstream channel width 337.3 ft q1 = Upstream unit discharge 4.5 ft2/s Flow depth through bridge 2.0 ft Velocity through bridge 3.0 ft/s Flow through bridge 1319.9 cfs Bridge opening width less pier widths 232.4 ft q2 = Unit discharge in the constricted opening 6.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.112 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 13.2 Ift Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 3.2 1.4 Wingwall 2.47 8.0 2.0 5.9 1.1 4.8 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 10 Page 410 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition US 101 NB On Ramp Units = (Metric or English) English Right Overbank = Abutment 3 (North) y1 = Upstream flow depth 4.2 ft Upstream velocity 1.6 ft/s Upstream flow 2602.6 cfs Upstream channel width 154.3 ft q1 = Upstream unit discharge 6.5 ft2/s Flow depth through bridge 4.0 ft Velocity through bridge 2.0 ft/s Flow through bridge 2119.5 cfs Bridge opening width less pier widths 93.3 ft q2 = Unit discharge in the constricted opening 8.1 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.112 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 4.1 ft Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 4.1 1.3 Wingwall 2.57 10.5 4.0 6.5 0.9 5.6 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 11 Page 411 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Left Overbank = MSE Walls at the South y1= Upstream flow depth 4.1 ft Upstream velocity 2.3 ft/s Upstream flow 1128.2 cfs Upstream channel width 146.5 ft q1 = Upstream unit discharge 9.5 ft2/s Flow depth through bridge 4.2 ft Velocity through bridge 1.7 ft/s Flow through bridge 1361.0 cfs Bridge opening width less pier widths 172.1 ft q2 = Unit discharge in the constricted opening 7.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = (� )3/7 quf /f Equation 8.7 t, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 16.8 Ift Ymax = aAYc or Ymax = aBYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 6.8 0.8 Wingwall 1.00 6.8 4.2 2.6 1.2 1.4 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 12 Page 412 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Right Overbank = MSE Walls at the North y1= Upstream flow depth 4.7 ft Upstream velocity 2.1 ft/s Upstream flow 1127.4 cfs Upstream channel width 262.5 ft q1 = Upstream unit discharge 9.9 ft2/s Flow depth through bridge 3.0 ft Velocity through bridge 2.1 ft/s Flow through bridge 955.2 cfs Bridge opening width less pier widths 290.5 ft q2 = Unit discharge in the constricted opening 6.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = (� )3/7 quf / f Equation 8.7 t, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 5.9 ft Ymax = aAYc or Ymax = aBYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.9 0.6 Wingwall 1.00 5.9 3.0 3.0 1.2 1.7 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 13 Page 413 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) 200-year Scour Summary Tables Scour Data Tables Prado West Overcrossing, Bridge No. 49C#### Prado West Overcrossing, Bridge No. 49C#### Short Term (Local)a MMMM Long Term (Degradation andShort Term ft) Scour Depth (ft) Contraction) lft) ur Elevation Scour Der Bent 3 1 Bent 3 130.41 • Prado East Overcrossing, Bridge No. 49C#### Prado East Overcrossing, Bridge No. 49C#### Support Degradation M No. Scour Depth (ft) Scour Depth (ft) Short Term Contraction) (Sftj ur Elevation Scour Der a • 1Abut 3 132.0 2.9 US 101 NB • • Bridge No.49 #### US 101• • Bridge No. Short Term (Local)Short EMMM Term ft) Scour Depth (ft) No. Contraction) (Sftj ur Elevation Scour Der .• US 101 NB • • Bridge No. 49 #### US 101: • • Bridge No. 49 Support Degradation Contraction Short Term (Local) No. Scour Depth (ft) Scour Depth (ft) Scour Depth (ft) Support Long Term (Degradation and Short Term No. Contraction) (Sftj ur Elevation Scour Der Bent 2 N/A 11 2.7 Bent 2 133.0 2.7 Page 414 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge Prado Road West Overcrossing Support Abut 1 Bent 2 Bent 3 Equation /6.7: \ i=YI- IZyo-i/a KU Variable Value Unit Description g 62.4 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 4.9 4.1 4.0 ft/s average velocity in contracted section n 0.04 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 2.5 2.5 1.7 ft Upstream flow depth i 1.3 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS-ua = 0.94y1 - / a 9Yi gny1 Variable Value Unit Description yl 0.7 0.8 0.5 m Upstream average flow depth Vz 1.5 1.3 1.2 m/s Average velocity in contracted section K 1 1 1 1.486 for U.S. Customary, and 1.0 for S.I. P 1000 1000 1000 kg/m^3 Density of water g 9.81 9.81 9.81 m/s^2 acceleration due to gravity ys .k 1 0.6 0.5 0.4 m Jultimate contraction scour y= i, 1 2.1 1 1.7 1 1.4 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 1 Page 415 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge Prado Road East Overcrossing Support Bent 2 Abut 3 Equation /6.7: \ i=YI— IZyo—i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.5 2.2 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 3.5 3.8 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS—ua = 0.94y1 — / a 9Yi gny1 Variable Value Unit Description yl 1.1 1.2 m Upstream average flow depth Vz 0.8 0.7 m/s Average velocity in contracted section K 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity ys .k 1 0.3 0.3 im jultimate contraction scour y= i, 1 1.1 1 1.0 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 2 Page 416 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge US 101 NB Off Ramp Support Abut 1 Bent 2 Equation /6.7: \ i=YI— IZyo—i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 3.4 2.9 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 2.2 3.3 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS—ua = 0.94y1 — / a 9Yi gny1 Variable Value Unit Description yl 0.7 1.0 m Upstream average flow depth Vz 1.0 0.9 m/s Average velocity in contracted section K 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity ys ue 0.4 0.4 m Ultimate contraction scour y= i, 1 1.3 1 1.3 ft Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 3 Page 417 of 1059 FN US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB On Ramp Support Bent 2 Abut 3 Equation 6.7: T = Y �_)2 A-1/3 KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 0.5 2.5 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.7 4.7 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83VZ p gY1 gnyl 3 Variable Value Unit Description yl 0.8 1.4 m Upstream average flow depth Average velocity in contracted section 1.486 for U.S. Customary, and 1.0 for S.I. Density of water acceleration due to gravity Vz 0.1 0.8 m/s K 1 1 p 1000 1000 kg/m^3 g 9.81 9.81 m/s^2 y= .k 1 0.0 0.4 m jultimate contraction scour y= i, 1 0.0 1 1.3 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 4 Page 418 of 1059 FN US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge VISE Walls Support Intersection of Prado Rd with US 101 Ramps Equation 6.7: T = Y �_)2 A-1/3 KU Variable Value Unit Description g 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.4 ft/s average velocity in contracted section n 0.04 Manning's roughness coefficient K 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 4.8 ft Upstream flow depth i 1.3 N/m^2=Pa Critical shear stress of channel bed material (From Figure 6.11) Equation 6.6: (K Tc �;3VZ pY1 gnyl 3 Variable Value Unit Description yl 1.5 m Upstream average flow depth Vz 0.7 m/s Average velocity in contracted section K 1 1.486 for U.S. Customary, and 1.0 for S.I. P 1000 kg/m^3 Density of water g 9.81 m/s^2 acceleration due to gravity y= .k 0.4 Im jultimate contraction scour y= i, 11.2 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 5 Page 419 of 1059 F:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K,.K a0.6s (2.6V, — V, o.7 Variable Value Unit Description Bridge Prado Road West Overcrossing Support Bent 2 Bent 3 # of Columns 3 3 a 5 5 ft Pier width L 15 15 ft Pier length L/a 3 3 If L/a is larger than 12, then use 12 as a maximum 6 0 30 degrees Angle of attack of flow Group of Group of cylinders cylinders Piershape K1 1 1 Correction factor for pier shape K2 1.0 1.8 Correction factor for angle of attack V1 3.0 3.4 ft/s Approach velocity Vc 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 ft/s^2 ys 6.7 13.0 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 6 Page 420 of 1059 F:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K1KZa0.65 (2.6V, — V, o.7 Variable Value Unit Description Bridge Prado Road East US 101 NB Off US 101 NB On Overcrossing Ramp Ramp Support Bent 2 Bent 2 Bent 2 # of Columns 2 4 2 a 5 4 4 ft Pier width L 20 8 8 ft Pier length L/a 4 2 2 If L/a is larger than 12, then use 12 as a maximum 6 0 0 0 degrees Angle of attack of flow Group of Group of Group of cylinders cylinders cylinders Piershape K1 1 1 1 Correction factor for pier shape K2 1.0 1.0 1.0 Correction factor for angle of attack V1 2.6 3.4 1.5 ft/s Approach velocity Vc 0.5 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 32.2 ft/s^2 ys 5.9 6.4 2.7 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 7 Page 421 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition Prado Road West Overcrossing Units = (Metric or English) I English Right Overbank = Abutment 1 (West) y1 = Upstream flow depth 2.5 ft Upstream velocity 2.8 ft/s Upstream flow 3628.7 cfs Upstream channel width 559.6 ft q1 = Upstream unit discharge 6.9 ft2/s Flow depth through bridge 3.0 ft Velocity through bridge 4.9 ft/s Flow through bridge 3890.8 cfs Bridge opening width less pier widths 420.4 ft q2 = Unit discharge in the constricted opening 14.7 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour 3/7 6 Yc = Ci ( ) Equation 8.7 / Kuf Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 6.8 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 6.8 2.1 Wingwall 1.89 12.9 3.0 9.9 2.1 7.8 ft Ft Ft Ft Ft Ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 8 Page 422 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition Prado Road East Overcrossing Units = (Metric or English) English Left Overbank = Abutment 3 (East) y1 = Upstream flow depth 3.8 ft Upstream velocity 2.7 ft/s Upstream flow 3353.3 cfs Upstream channel width 220.4 ft q1 = Upstream unit discharge 10.3 ft2/s Flow depth through bridge 3.8 ft Velocity through bridge 2.2 ft/s Flow through bridge 2300.0 cfs Bridge opening width less pier widths 284.6 ft q2 = Unit discharge in the constricted opening 8.3 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = Ci / 3/7 ( Kuf ) 6 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 7.6 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.6 0.8 Wingwall 1.00 7.6 3.8 3.8 1.0 2.9 rt rt rt rt rt hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 9 Page 423 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition US 101 NB Off Ramp Units = (Metric or English) English Left Overbank = Abutment 1 (South) y1 = Upstream flow depth 2.2 ft Upstream velocity 2.5 ft/s Upstream flow 1845.0 cfs Upstream channel width 337.3 ft q1 = Upstream unit discharge 5.4 ft2/s Flow depth through bridge 2.2 ft Velocity through bridge 3.4 ft/s Flow through bridge 1587.8 cfs Bridge opening width less pier widths 237.3 ft q2 = Unit discharge in the constricted opening 7.3 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = Ci / 3/7 ( Kuf ) 6 Equation 8.7 2c = Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 3.7 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 3.7 1.4 Wingwall 2.49 9.3 2.2 7.1 1.3 5.8 ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 10 Page 424 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition US 101 NB On Ramp Units = (Metric or English) English Right Overbank = Abutment 3 (North) y1 = Upstream flow depth 4.7 ft Upstream velocity 1.8 ft/s Upstream flow 3621.2 cfs Upstream channel width 144.7 ft q1 = Upstream unit discharge 8.3 ft2/s Flow depth through bridge 4.7 ft Velocity through bridge 2.5 ft/s Flow through bridge 2886.0 cfs Bridge opening width less pier widths 103.3 ft q2 = Unit discharge in the constricted opening 11.9 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear-Wat1er Condition Abutment Scour Yc = I i 13/7 I K. 16 Equation 8.7 2c = Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 5.7 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.7 1.4 Wingwall 2.42 13.7 4.7 9.0 1.3 7.7 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 11 Page 425 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Left Overbank = MSE Walls at the South y1 = Upstream flow depth 4.5 ft Upstream velocity 2.9 ft/s Upstream flow 1615.4 cfs Upstream channel width 146.5 ft q1 = Upstream unit discharge 12.9 ft2/s Flow depth through bridge 4.4 ft Velocity through bridge 1.9 ft/s Flow through bridge 1875.2 cfs Bridge opening width less pier widths 192.4 ft q2 = Unit discharge in the constricted opening 8.4 ft2/s Abutment scour equation = Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour .yc = I � 13/7 I �uf 16 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ft^2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ft^3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 7.7 ft Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.7 0.7 Wingwall 1.00 7.7 4.4 3.3 1.2 2.1 ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 12 Page 426 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Right Overbank = MSE Walls at the North y1 = Upstream flow depth 5.0 ft Upstream velocity 2.6 ft/s Upstream flow 1519.9 cfs Upstream channel width 266.2 ft q1 = Upstream unit discharge 13.0 ft2/s Flow depth through bridge 3.2 ft Velocity through bridge 2.4 ft/s Flow through bridge 1308.2 cfs Bridge opening width less pier widths 297.3 ft q2 = Unit discharge in the constricted opening 7.7 ft2/s Abutment scour equation = Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour .yc = I � 13/7 I �uf 16 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ft^2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ft^3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 7.2 ft Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.2 0.6 Wingwall 1.00 7.2 3.2 4.0 1.2 2.8 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 13 Page 427 of 1059 DRAFT APPENDIX F: Draft Structure Preliminary Geotechnical ntconsor Report (SPGR) Bridges Page 428 of 1059 STRUCTURE PRELIMINARY GEOTECHNICAL REPORT BRIDGES US 101 and Prado Road Interchange Project San Luis Obispo, California 05-SLO-101- PM 26.5-27.3 Caltrans Project No. 113-0000-0405; EA 05-11-1640 City Specification No. 2091613-02 Yeh Project No.: 223-400 December 23, 2025 INDEPENDENT QUALITY CONTROL REVIEW US 101 and Prado Road Interchange Project IIJIT C-EIGNER/ORIGINATCF. ��'f, 12/18/25 PE -RC CONFIRMS READY FOR QC ' L 12/18/25 INDEPENDENT QC REVIEW DONE 12/22/25 PE- RC CONCURS WITH QC REVIEW 12/23/25 QC COMMENTS INCORPORATE-- 12/23/25 QC COMMENTS BACKCHECKED/VERIFIED 12/23/25 Prepared for: Consor North America, Inc. 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95670 Attn: Dace Morgan, P.E. Prepared by: Yeh and Associates, Inc. 391 Front Street, Suite D Grover Beach, California 93433 Phone: 805-481-9590 IYehN and Associates, Inc. Geotechnical • Geological • Construcl ion Ser% ices Page 429 of 1059 INYeh and Associates, Inc. Geotechnical • Geological • Construction Services December 23, 2025 Consor North America, Inc. 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95670 391 Front Street, Suite D Grover Beach, CA 93433 (805) 481-9590 www.yeh-eng.com Project No. 223-400 Attn: Dace Morgan, P.E. Subject: DRAFT Structure Preliminary Geotechnical Report — Bridges, US 101 and Prado Road Interchange Project, San Luis Obispo, California, 05-SLO-101-PM26.5-27.3, Caltrans Project No. 113-0000-0405; EA 05-11-1640, City Specification No. 2091613-02 Dear Ms. Morgan: Yeh and Associates, Inc. is pleased to submit this Structure Preliminary Geotechnical Report for the design of the US 101 overcrossing and viaducts for improvements associated with the U.S. Route 101 (US 101) and Prado Road Interchange Project in San Luis Obispo, California. This report was prepared in accordance with the terms of agreement between Yeh and Associates and Consor North America, Inc. (Consor) dated April 11, 2025. This Structure Preliminary Geotechnical Report (SPGR) for Bridges provides preliminary geotechnical recommendations for the foundations for the overcrossing. This report was prepared in general accordance with Caltrans guidelines for Structure Preliminary Geotechnical Reports (Caltrans 2024c) and provides a discussion of the project alternatives, site conditions, geologic conditions, seismicity and faulting, geotechnical considerations regarding overcrossing structure and ramp foundation alternatives, as well as additional field and laboratory data needed for design. We appreciate the opportunity to be of service. Please contact Judd King at 805-481-9590 x285 or ikin@yeh-en�.com if you have questions or require additional information. Sincerely, YEH AND ASSOCIATES, INC. DRAFT Judd J. King, PE, GE Senior Geotechnical Engineer Colorado DRAFT Jamie L. Ross, PE, GE Senior Project Engineer California Denver I Colorado Springs I Durango I Glenwood Springs I Grand Junction I Greeley Grover Beach I Ventura Page 430 of 1059 Structure Preliminary Geotechnical Report — Overcrossing US-101 at Prado Road Interchange Project DRAFT Katrina Ocampo, EIT Engineering Intern Colorado Reviewed by: DRAFT Gregg L. Fiegel, PhD, PE, GE Senior Project Specialist Project No. 223-400 December 23, 2025 California Denver I Colorado Springs I Durango I Glenwood Springs I Grand Junction I Greeley Grover Beach I Ventura Page 431 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 Table of Contents 1. INTRODUCTION.........................................................................................................................3 2. PROJECT DESCRIPTION..............................................................................................................3 3. GEOTECHNICAL EXPLORATION..................................................................................................5 3.1 CONE PENETRATION TEST (CPT) SOUNDINGS....................................................................................6 3.2 PREVIOUS STUDIES.......................................................................................................................6 4. GEOTECHNICAL CONDITIONS.....................................................................................................7 4.1 GEOLOGY...................................................................................................................................7 4.2 SURFACE CONDITIONS...................................................................................................................9 4.2.1 TERRAIN AND TOPOGRAPHY....................................................................................................9 4.2.2 SURFACE WATER AND DRAINAGE.............................................................................................9 4.2.3 EXISTING FACILITY................................................................................................................9 4.2.4 EXISTING UTILITIES.............................................................................................................10 4.3 SUBSURFACE CONDITIONS............................................................................................................10 5. GROUNDWATER......................................................................................................................11 6. SCOUR DATA...........................................................................................................................13 7. CORROSION EVALUATION.......................................................................................................13 8. SEISMIC INFORMATION...........................................................................................................14 8.1 GROUND MOTION HAZARD..........................................................................................................14 8.2 OTHER SEISMIC HAZARDS............................................................................................................16 8.2.1 SURFACE FAULT RUPTURE....................................................................................................166 8.2.2 LIQUEFACTION POTENTIAL....................................................................................................17 8.2.3 SEISMICALLY INDUCED GROUND SETTLEMENTS.........................................................................17 8.2.4 LIQUEFACTION -INDUCED LATERAL SPREADING..........................................................................17 8.2.5 SEISMIC SLOPE STABILITY.....................................................................................................17 9. GEOTECHNICAL RECOMMENDATIONS.....................................................................................18 9.1 PRELIMINARY FOUNDATION RECOMMENDATIONS.............................................................................18 9.1.1 CAST -IN -DRILLED -HOLE (CIDH) PILES....................................................................................20 9.1.2 DRIVEN PILES....................................................................................................................21 9.1.3 CAST -IN -STEEL -SHELL (CISS) PILES........................................................................................23 9.1.4 SPREAD FOOTINGS..............................................................................................................24 I � 1 Page 432 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 9.1.5 PREFERRED PILE FOR DESIGN................................................................................................25 10. ADDITIONAL FIELD WORK AND LABORATORY TESTING.......................................................27 11. LIMITATIONS.......................................................................................................................27 12. REFERENCES........................................................................................................................27 List of Figures FIGURE 1: PROJECT LOCATION MAP............................................................................................................................... 3 FIGURE 2: PROPOSED LAYOUT (CONSOR 2025B)............................................................................................................. 4 FIGURE 3: GEOLOGIC MAP (WIEGERS 2010)................................................................................................................... 8 FIGURE 4: PRELIMINARY ARS CURVE............................................................................................................................ 15 FIGURE 5: PRELIMINARY FACTORED NOMINAL AXIAL PILE RESISTANCE VERSUS EMBEDMENT DEPTH INTO ROCK ....................... 26 List of Tables TABLE 1: SUMMARY OF GROUNDWATER DATA(ERS)...................................................................................................... 11 TABLE 2: RECOMMENDED GROUND MOTION PARAMETERS FOR PRELIMINARY GEOTECHNICAL DESIGN ................................... 14 TABLE 3: RECOMMENDED HORIZONTAL PSEUDOSTATIC COEFFICIENT FOR SLOPE STABILITY ................................................... 18 List of Plates Previous and Current Field Exploration Map ......................... Subsurface Profile A -A............................................................ Subsurface Profile B-B'........................................................... List of Appendices Appendix A — CPT Plots and Liquefaction Analyses ......................................................................1 ...................................................................... 2 ...................................................................... 3 Page 25CPT-01 to 04.................................................................................................................... A-1 to 28 Appendix B — Relevant Historical Data — Borings, CPTs, Geophysical Surveys and Laboratory Madonna Road OC (Caltrans 1961)...............................................................................................B-1 Laguna Lift Station (Fugro 1999)......................................................................................... B-2 to 17 San Luis Obispo Water Reuse (Fugro 2002)...................................................................... B-18 to 34 Prado Road OC at US 101 (Parikh 2002).....................................................................................B-35 SLO PCE Plume Characterization (WSC 2022)................................................................... B-36 to 49 Prado Road Bridge (Yeh 2024)........................................................................................ B-50 to 100 I � 2 Page 433 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 1. INTRODUCTION �I i Consor North America, Inc. (Consor) retained Yeh and Associates (Yeh) to provide preliminary geotechnical o�° CITY OF SAN LUIS OBISPO recommendations for the design of PM 27.3 the US 101 and Prado Road Interchange Project in San Luis PROJECT LOCATION i Obispo, California. The project includes reconstruction of theP northbound ramps, a new auxillary lane connecting to the Madonna PM - 26. Prado Road Road interchange to the north, realignment of Elks Lane, and the new Prado Road overcrossing at US �l 101. Project limits extend about a Y2- h' j North mile south from the existing Madonna Road Interchange and m / through the existing at -grade F Q intersection with the northbound 10 �. o 3,000 ramps at the existing Prado feet J Base Map: ArcGIS Earth (2017) Interchange. Figure 1: Project Location Map The project location is shown in Figure 1. This Structure Preliminary Geotechnical Report (SPGR)for Bridges provides preliminary geotechnical recommendations for foundations as input for type selection for Phase 1 of the PS&E process for the project. Preliminary geotechnical considerations and recommendations are provided for the proposed overcrossing structure and associated ramp structures relative to foundation support, scour, corrosion, seismic hazards, structure type, construction, and additional field work and laboratory testing for design. The preliminary characterization of the subsurface conditions is based on boring information from previous explorations performed in the vicinity of the project site as well as cone penetration test (CPT) soundings performed for Phase 1 of the project (see Section 4.3). A Structure Preliminary Geotechnical Report (SPGR)for Earth Retaining Structures (ERS) and a Preliminary Geotechnical Design Report (PGDR) will be submitted separately. 2. PROJECT DESCRIPTION Preliminary alignment and design information for the project was provided by Consor (2025a, 2025b). The project generally consists of the extension of Prado Road over US 101 to connect to Dalidio Drive VA3 Page 434 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 within the City of San Luis Obispo and reconstruction of the interchange. The project limits will extend along US 101 from approximately Post Mile 26.5 at the southern limits of the project site to Post Mile 27.3 at the Madonna Road northbound offramp. The approach from Prado Road will extend for about 1,000 feet from the existing Prado Road Bridge at San Luis Obispo Creek Bridge to an existing roundabout at the eastern terminus of Dalidio Drive about 500 feet west of US 101. The approved project is described as Alternative 3 in the Project Report (GHD 2018) and environmental documents for the project (Caltrans 2023). The City and Consor have been conducting a Value Analysis to determine if improvements to the approved project could be made to reduce the overall construction cost of the improvements. On November 4, 2025, the City Council approved modifying the approved project from the Project Report to the one shown in Figure 2. North 0 400 - fCCI Figure 2: Proposed Layout (Consor 2025b) The new interchange will essentially be a half -diamond, consisting of northbound ramps and at -grade controlled intersections. The project components include the west side and east side approaches to the overcrossing, the elevated northbound US 101 on- and off -ramps, and the northbound US 101 auxiliary lane between Prado Road and Madonna Road. Both the west side and east side approaches for the overcrossing need to be elevated to connect to the proposed bridge over US 101. Earth retaining structures (ERS) are proposed to support the approaches to the overcrossing and the elevated northbound ramps. The project is also within the mapped 100-year flood zone. As a result, the structures will be elevated above grade to limit impacts to the mapped flood zone (GHD 2018). The proposed bridge structures generally include the following: • A new overcrossing will be provided to extend Prado Road over US 101. Preliminary plans (Consor 2025a) show the overcrossing with seven spans and a total length of approximately 1,050 feet. The overcrossing will be approximately 65 feet wide to accommodate two travel lanes, a left turn lane, 5-foot shoulders, a shared -use path on the south side, and a sidewalk on the north side of the structure. The east end of the overcrossing would be wider to accommodate two travel lanes in each direction at the new Prado Road and Elks Lane 1A 4 Page 435 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 intersection. There will be a 11-foot-wide median separating the eastbound and westbound lanes. The current plans show the overcrossing with a clear span of about 150 feet across US 101. The bridge will be constructed on a vertical curve over US 101. While the bridge alignment is relatively straight across US 101 it also includes a horizontal curve toward Dalidio Drive leading into the west approach. The overcrossing will provide at least 16.5 feet of vertical clearance above US 101. • The northbound ramps will include viaducts intersecting with Prado Road at the new overcrossing: o The viaduct for the northbound off -ramp will be approximately 285 feet long with 2 spans before connecting to the overcrossing. The viaduct is shown as a 40-foot-wide cast -in -place box girder that will accommodate left and right turn lanes. The southern end of the ramp would be supported by a seat -type abutment. Each bent is shown as being supported on two 48-inch-diameter columns with each column supported on a single cast -in -drilled hole pile foundation. o The viaduct for the northbound on -ramp will be approximately 295 feet long with 2 spans connected to the overcrossing. The viaduct is shown as a 28-foot-wide cast -in - place box girder that will accommodate a single lane with shoulder onto northbound US 101. The northern end of the ramp would be supported by a seat -type abutment. The first bent is shown as being supported on three 48-inch-diameter columns; the second bent will be supported by two 48-inch diameter columns. Each column will be supported on a single cast -in -drilled hole pile foundation. o The intersection of the northbound off -ramp viaducts and overcrossing will occur at approximately 28 feet above existing site grades. The bridge ends of the viaducts will be approximately 20 feet above existing site grades. The project will also include retaining walls to support the bridge approaches as well as a new auxiliary lane, stormwater improvements, realigning Elks Lane, and the approach and roadway improvements. Associated utility, roadway striping, signage, pedestrian, and landscaping improvements will also be provided. 3. GEOTECHNICAL EXPLORATION This geotechnical evaluation was based on review of geotechnical data collected from various previous studies and the results of four Cone Penetration Test (CPT) soundings performed for this phase of the project. The locations of the CPTs performed for this study are shown on Plate 1 along with explorations completed for previous studies. The logs for the CPT soundings are presented in Appendix A and previous study data is presented in Appendix B. VA5 Page 436 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 3.1 CONE PENETRATION TEST (CPT) SOUNDINGS The CPT subcontractor for this project was Gregg Drilling (Gregg) of Signal Hill, California. Gregg advanced four soundings using a hydraulic ram mounted inside a 30-ton truck on July 10, 11, and 29, 2025. CPT soundings were advanced to depths ranging from approximately 57 to 62 feet below the ground surface. Each sounding was terminated once refusal was encountered. Refusal was characterized by lifting or tilting of the CPT rig due to high push load. Once a sounding was completed, the void above the refusal depth was backfilled with bentonite chips. Plate 1 shows the approximate locations of the four CPT soundings (25CPT-01 through 25CPT-04) relative to the proposed interchange improvements.. Logs of the CPT soundings are presented in Appendix A. The soundings were performed in general accordance with ASTM D-5778 using an electric piezocone penetrometer. The piezocone penetrometer had a diameter of approximately 1.7 inches with a tip area of 15 square centimeters (cm2) and a sleeve area of 225 cm2. The cone tip resistance (qc), sleeve friction (fs), and penetration pore water pressures measured behind the tip (in the u2 location) were recorded at approximately 3-centimeter intervals during penetration using an on -board computer. The friction ratio (FR, the ratio of sleeve friction to tip resistance in percent) was computed for each value of qc and fs recorded. The data and soil behavior type classifications were used in subsequent geotechnical analyses and to evaluate soil types and boundaries for analyses. Upon removal of the CPT rod, the soil generally collapsed to near the groundwater level (if encountered). Seismic shear wave velocity testing was performed in CPT soundings 25CPT-01 through 04. To conduct the seismic shear wave test, the penetration of the cone was stopped, and the rods were decoupled from the rig. An automatic hammer was then triggered to send a shear wave into the ground. The distance from the source to the cone was calculated knowing the total depth of the cone and the horizontal offset distance between the hammer and the cone. A minimum of two tests must be performed at two different depths to calculate an interval shear wave velocity. The data collected were used to estimate an average shear wave velocity extrapolated to a depth of 100 feet below the existing ground surface at the project site (V530). 3.2 PREVIOUS STUDIES Previous geotechnical studies that were performed at or near the project location were reviewed for this project. Logs and laboratory data pertinent to this project included in Appendix B. The locations of the previous borings and CPT soundings are shown on Plate 1. Pertinent studies and data that were reviewed include: • Nine borings (B-1 through B-9) drilled by Caltrans (Caltrans 1961b) for the design of the overcrossing structure at US 101 and Los Osos Valley Road; YA 6 Page 437 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 • Four borings (B-1 through B-4) drilled by Caltrans (Caltrans 1963) for the design of the overcrossing structure at US 101 and Madonna Road; • Pile driving records from 1961, 1986, and 2015 (Caltrans 1961a, Caltrans 1986, MNS 2015) for the overcrossing structure at US 101 and Los Osos Valley Road as well as pile driving records from 1962 (Caltrans 1962) for the overcrossing structure at US 101 and Madonna Road; • A study performed by Unocal in 1990 (GeoResearch-Unocal 1990) for the evaluation of contaminated soil on Elks Lane at San Luis Obispo Creek. The evaluation included three borings (B-1 through B-3) and a monitoring well installed at the site. A well destruction report for the well was also prepared by Arcadis (Arcadis 2019); • Three borings (DH 1 through 3) drilled by Fugro (1999) for a proposed lift station at the SLO Water Reclamation Facility (WRF); • Five borings (B-305, 306, 401 through 403) drilled by Fugro (2002) for a proposed pipeline and reservoir for a recycled water project at the WRF; • Two borings (B-1 and B-2) drilled by Parikh (2002) for a proposed overcrossing structure at US 101 and Prado Road; • A study performed by Caltrans (Caltrans 2005) for the evaluation of an auxiliary lane on northbound US 101 between Prado Road and Madonna Road; • A study performed by Dokken (Dokken 2009) for the widening of the overcrossing structure at US 101 and Los Osos Valley Road. The evaluation included twenty-seven borings (B-1 through B-27) drilled at the overcrossing; • A study performed by Water Systems Consulting (WSC 2022) for characterization and remediation of a PCE plume. The study included exploratory borings and cone penetration test (CPT) soundings, including two borings (B-21 and B-24) as well as four CPT soundings (13- 18R and B-22 through B-24) within the project limits; and • A geotechnical study performed by Yeh and Associates (2025) for the Prado Road Bridge Replacement Project immediately east of the project limits. The study includes data from exploratory borings and a geophysical survey. 4. GEOTECHNICAL CONDITIONS 4.1 GEOLOGY The project site lies east of the Santa Lucia Range and within the Coast Ranges Geomorphic Province, which extends from the Transverse Ranges in southern California to the Klamath Mountains in northern California and into Oregon. The province is characterized by north to northwest trending mountain ranges bounded by the Pacific Ocean to the west and the Central Valley of California to the east. The ranges are predominantly composed of Jurassic- and Cretaceous -age rocks with Tertiary -age rock and Holocene sediments commonly overlying the older formations along the flanks and foothills 7 Page 438 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 of those ranges. Quaternary sediments are found within intervening drainages, valleys, and coastal areas. The regional geology as mapped by Wiegers (2010) is shown in Figure 3. Wiegers maps the surface geology in the site vicinity as units of Holocene to late Pleistocene age young alluvial floodplain deposits (Qya2). The young alluvial floodplain deposits are described by Wiegers as "unconsolidated sand, silt, and clay -bearing alluvium deposited on floodplains and along valley floors." The upper unit of the young alluvial floodplain deposits (Qya2) are bound by older young alluvial flood plain deposits (Qya1). Franciscan Melange (KJfm) is expected to underlie the alluvium at the project site. The Franciscan melange and serpentine (Jos) are mapped by Wiegers on hillsides northeast and northwest of the project site. Wiegers describes the Franciscan Melange as a "chaotic mixture of fragmented rock masses embedded in a penetratively sheared matrix of argillite and crushed metasandstone" with "individual rock masses contained in the matrix range from less than a meter to kilometers in scale." Mapped outcrops of greywacke sandstone, serpentine, and melange are common within the Franciscan melange. LEGEND: LYS Landslide Deposits (Holocene and Pliestocene) i CYoung Alluvial Flood -Plain Deposits, undivided (Holocene to late Pleistocene) )y �•- Young Alluvial Flood -Plain Deposits, Unit 1 Qyaa Young Alluvial Flood -Plain Deposits, Unit 2 Young Colluvial Deposits (Holocene to late Pliestocene) Jos Serpentinized Ultramafic Rocks (Jurassic) I KJfm Franciscan Melange (Cretaceous to Jurassic) APPROXIMATE PRELIMINARY PROJECT ALIGNMENT •�11 i Qya, I � \� 1 Mse Ma : Wiegers• Mark O. 2010. Geologic Map of the San Luis Obispo 75 Quadrangle, San Luis Obispo, Califorrna Figure 3: Geologic Map (Wiegers 2010) North J 0 2,000 feet IA 8 Page 439 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 Geologic structure in the region is generally characterized by a series of northwest trending faults and folds; such as predominant Quaternary faulting along the Los Osos Fault Zone, Edna Fault, Cambria Fault, and the Oceanic (West Huasna) Fault systems mapped approximately 1 miles southwest, 2 miles southwest, 3 miles northeast, and 5 miles northeast, respectively of the project site (USGS 2025). 4.2 SURFACE CONDITIONS 4.2.1 TERRAIN AND TOPOGRAPHY The project site is located along the San Luis Obispo Creek Valley in the City of San Luis Obispo. The layout of the existing site and project limits is shown on Plate 1. Prado Road currently has an at grade interchange with US 101 consisting of only northbound on- and off -ramps. Existing terrain along the project alignment is generally flat ground sloping easterly toward San Luis Obispo Creek at average grades of approximately 0.5 to 1 percent. Existing land use generally consists of commercial development within Madonna Plaza to the northwest of the proposed interchange. Land use along the west approach to the proposed interchange is currently being converted from agricultural row crops to mixed residential and commercial development. Land use northeast of the proposed interchange is mixed business, commercial, residential, and agricultural development. Existing developments along the north side of Prado Road include social services, charging stations, and a transit facility. The City of San Luis Obispo's Water Reclamation Facility is located on the south side of Prado Road and southeast of the proposed interchange. 4.2.2 SURFACE WATER AND DRAINAGE San Luis Obispo Creek flows southerly along the easterly side of US 101. The creek channel is generally incised with a thalweg elevation about 20 feet below the adjacent grades. The creek crosses beneath the Prado Road Bridge approximately 1,000 feet east of US 101. The creek meanders and runs alongside of the existing Caltrans right-of-way fence for about 200 to 300 feet ahead of the northbound off -ramp to Madonna Road, and adjacent to the proposed auxiliary lane alignment. 4.2.3 EXISTING FACILITY The existing US 101 and roadway improvements were generally made near or just above previous site grades. Existing embankment fills along US101 generally appear to be less than about 5 feet high. Prado Road is generally an at -grade street with intermittent curb, gutter and sidewalks. The streets and US 101 are paved with asphalt pavement. The existing pavements along Prado Road are generally in poor condition with areas of severe fatigue cracking. The pavements along the northbound ramps and US 101 are generally in fair to good condition with areas of light raveling of the pavement surface and along cold joints, and areas with low severity longitudinal cracks in the wheel paths. �� 9 Page 440 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 4.2.4 EXISTING UTILITIES Existing utilities generally consist of buried pipelines and services, as well as overhead power and utility services along Prado Road, along Elks Lane, and that cross US 101 near the proposed interchange. High voltage overhead power transmission lines cross US 101 above the existing northbound on -ramp. Other utilities include buried pipelines that cross underneath US 101 and likely along the Madonna Road Interchange. Location and mapping of existing utilities is not within scope of the geotechnical services for this report. 4.3 SUBSURFACE CONDITIONS The predominant geologic units encountered in previous studies (see Section 3.2 of this report) and interpreted from the cone penetration test (CPT) soundings performed by Yeh are surficial units of existing artificial fill (Af), alluvium (Qya), and older alluvium (Qoa) that overlie Franciscan melange (KJfm) bedrock. The approximate locations of current study and previous explorations are shown on Plate 1. Generalized north -south and east -west subsurface profiles based on those previous data are shown on Plates 2 and 3. Descriptions of the units, as encountered in the explorations are summarized below. Artificial Fill (Af). Artificial fill is generally present along the existing roadways as well as in developed areas in association with existing pavements and utilities. The existing fill within the proposed improvement areas is generally expected to be less than about 5 feet thick. The fill is likely to be derived from clayey soil associated with local borrow sources, with the exception of select material that could have been used as fill for the existing pavement and utility trench backfills. Alluvium (Qya). Young alluvium was encountered in most of the explorations at the ground surface or underlying existing fill and pavement materials. The young alluvium encountered is interpreted to extend to depths of approximately 30 to 40 feet below the existing ground surface. This unit consisted of two predominant subunits (Qyal and Qyaz) that were mainly differentiated based on their consistency. The young alluvium was underlain by older alluvium (Qoa) in most of the explorations. Qyal. This subunit consisted of predominantly soft to hard clay and sandy clay. The unit was locally interbedded with layers and lenses of loose to medium dense clayey sand and clayey gravel. The unit appears to be desiccated and moderately over -consolidated clayey soil near or above the groundwater table. This subunit is generally considered to be the upper zone of the young alluvial deposits described by Wiegers (2010). Qya2. This subunit consisted of predominantly soft to medium stiff clay with varying amounts of sand and gravel with thin interbedded layers of loose to medium dense clayey sand with VAPage 441 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 varying amounts of gravel. This unit appears to be associated with lightly to moderately over consolidated clayey soil that is most often below the groundwater table. Historically this unit is prone to consolidation settlement. This subunit is generally considered to be the lower zone of young alluvial deposits described by Wiegers (2010). Older Alluvium (Qoa). Older alluvium was encountered below the upper units in most of the explorations that were deep enough to penetrate the young alluvium. The older alluvium was typically encountered at depths ranging between about 40 and 60 feet below the ground surface but may be encountered at shallower depths below Prado Road closer to San Luis Obispo Creek. The unit was a mixture of sediments that were composed of medium to very dense silty sand, clayey sand and gravel and stiff to very hard clay and sandy clay. The extents and composition of fine-grained, sand and gravel sediments varied between explorations. The older alluvium was underlain by Franciscan melange bedrock where penetrated. Franciscan Melange (KJfm/KJfmv). Franciscan melange was encountered below the alluvium and older alluvium and is the predominant geologic unit that underlies all other sediments in the project vicinity. Borings and CPT soundings from the explorations commonly met refusal near the bedrock surface or shallow depths into it. The depth to bedrock is estimated to be about 60 feet below the ground surface near the center of the proposed interchange. The melange primarily consisted of blocks of moderately hard to hard graywacke in a matrix of soft intensely fractured and sheared claystone (KJfm). Borings performed by Yeh (2025) for the Prado Road Bridge project were cored to a depth of about 100 feet, or approximately 60 feet into the Franciscan melange bedrock. 5. GROUNDWATER Groundwater conditions in the vicinity of the project site are generally influenced by stream flow levels in San Luis Obispo Creek, and the depth to bedrock below the site. Groundwater was encountered at various depths and locations in previous studies. A summary of groundwater measurements reported from the previous studies is presented in Table 1. Table 1 includes borings presented in referenced studies (see Section 3.2) that encountered groundwater. Data reported in metric units were converted to imperial units before listing them in Table 1. Table 1: Summary of Groundwater Data (ERS) VA 11 f 1 Page 442 of 059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 Ground Groundwater Measurements Boring No. Study Surface El. Depth Elevation Location/Project (feet) (feet) (feet) Date Measured Notes DH-1 Lift station is located south of the Fugro (1999) 122.0 14.5 107.5 10/25/1999 City water reclamation plant and Laguna Lift Station east side of US 101 near PM26.0 B-1 Parikh (2002) 132.7 11.3 121.4 6/26/2000 West abutment vicinity Prado Rd-US101 OC B-2 Parikh (2002) 135.5 17.5 118.0 6/27/200 East abutment vicinity Prado Rd-US101 OC B-402, 403 111.1- Drilled in Prado Road between US Fugro (2002) 136.1 24.5-25.0 2/5-8/2002 111.E 101 and Prado Road Bridge SLO Water Reuse B-13 Ground elevations are not WSC (2022) 152 22 130 3/24/2022 reported and are estimated from Madonna Rd Google Earth at east of OC 35.267142-, - 120.672137° B-17 Ground elevations are not WSC (2022) 138 25 113 6/29/2022 reported and are estimated from US101 SB Onramp at Google Earth at Madonna Rd 35.263172-, - 120.674106° About 600 feet south of western terminus of project B-18R Ground elevations are not WSC (2022) 120 9 111 6/27/2022 reported and are estimated from Froom Ranch Way Google Earth at 35.256650°, - 120.678056° Ground elevations are not B 20 reported and are estimated from WSC (2022) 129 18 111 3/22/2022 Google Earth at El Mercado 35.260627-, - 120.675801° Ground elevations are not B 21 reported and are estimated from WSC (2022) 130 13 117 3/23/2022 El Mercado Google Earth at 35.259395°, - 120.674163° Ground elevations are not B 22 reported and are estimated from WSC (2022) 125 30 95 3/24/2022 Google Earth at Prado Rd 35.256498°, - 120.673503° Ground elevations are not B 23 reported and are estimated from WSC (2022) 128 20 118 3/25/2022 Google Earth at Prado Rd 35.255653-, - 120.671779° Ground elevations are not B 24 reported and are estimated from WSC (2022) 130 16 114 3/31/2022 Prado Rd Google Earth at 35.255172', - 120.670586° VA Page 443 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 San Luis Obispo Creek flows southerly along the eastern side of US 101. The channel of San Luis Obispo Creek is incised with a thalweg elevation that is about 20 feet below adjacent grades. Groundwater conditions and gradients generally appear to follow San Luis Obispo Creek with the shallowest depths to groundwater of about 10 feet in explorations performed on the west approach to the proposed Prado Road Overcrossing, and to depths of about 15 to 20 feet in explorations performed on the east approach to the proposed overcrossing. Groundwater levels and soil moisture conditions will vary seasonally and in association with changes in precipitation, runoff, irrigation, pumping, and other factors. Additionally, groundwater and the control of groundwater have been an issue on projects in the vicinity such as the Laguna Lift Station (Fugro 1999) and the SLO WRF Water Reuse project (Fugro 2002). There are reported difficulties associated with dewatering of excavations as well as impacts to adjacent structures as a result of dewatering. 6. SCOUR DATA The site is within the 100-year flood plain and will be subject to episodic flooding. Newly graded slopes and fills will be vulnerable to erosion. Scour analyses will be performed by others for the next phase of the project. Design of foundations for the overcrossing and ramp structures should consider potential impacts from scour, if needed. 7. CORROSION EVALUATION Soil within the project area is not considered corrosive based on laboratory data from previous studies in the site vicinity (Yeh 2025). Corrosion testing should be performed on soil and water samples obtained from the site -specific field exploration program for the final design of the project. The project site is approximately 6 miles from the Pacific Ocean; therefore, it is not considered to be within a marine environment based on the Caltrans (2021b) Corrosion Guidelines. ��13 Page 444 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 8. SEISMIC INFORMATION 8.1 GROUND MOTION HAZARD Seismic data were generated using the selected site parameters and ARS Online (Caltrans 2025b) to estimate ground motion parameters in accordance with Appendix B of the Caltrans (2025a) Seismic Design Criteria (SDC) and the Caltrans (2021a) Geotechnical Manual — Design Acceleration Response Spectrum. The SDC defines the Safety Evaluation Earthquake (SEE) as an earthquake having a 975- year-return period and is used for geotechnical design for slopes, retaining walls, bridges, and other structures. Seismic data were generated for site conditions using the location of the proposed overcrossing. The shear wave velocity for the project site was estimated from the seismic CPT data obtained for this project and the Yeh (2025) report prepared for the Prado Bridge Replacement Project. The Yeh (2025) data were used because the geologic conditions appear to be similar to those at the project site based on previous data (Parikh 2002). Table 2 presents the preliminary seismic data used in Yeh's preliminary analyses. These data provide the basis for estimating seismic parameters for seismic slope stability analyses and input for analyzing liquefaction hazards. Seismic data will be generated for specific structure and point of analyses as the project design progresses and geotechnical data are collected for those improvements. The preliminary design response spectrum estimated for the SEE is presented in Figure 4. Table 2: Recommended Ground Motion Parameters for Preliminary Geotechnical Design 17A Page 445 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 1.4 1.2 1.0 2.0 3.0 4.1` U 6.0 7.0 8.0 9.0 Period, T (sec) — — Design Response Spectrum ARS Online: V 4.0 Mean Magnitude: 7.0505 at 25.37 km Spectral Damping: 5 percent O Peak Ground Accleration = 0.39g Latitude: 35.2569 degrees Longitude:-120.6748 degrees V"C: 320 meters/second Figure 4: Preliminary ARS Curve 10.0 The Caltrans (2025a) Seismic Design Criteria notes that a site -specific ground response analysis is required for sites that include any of the following criteria: • The estimated shear wave velocity in the upper 100 feet (or 30 meters) of the site, Vs30, is less than 180 meters per second; • The soil profile contains one or more layers that are at least 5 feet thick which have a shear wave velocity less than 120 meters per second; • The site contains soil that has a potential for strength loss or volume change during seismic loading including liquefiable, sensitive clay, or collapsible soil; • The site contains one or more layers of peat and/or highly organic clay which has a thickness of at least 10 feet; • The site contains a layer of highly plastic clay (with a plastic index, PI, greater than 75) which has a thickness of at least 25 feet; and/or VA Page 446 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 • The site contains a layer of soft to medium stiff clay (with an undrained shear strength, s, less than 1,000 pounds per square foot). Layers of sand encountered within the older alluvium are considered potentially liquefiable, as discussed in Section 8.2.2. The Caltrans (2022a) Geotechnical Manual forSite-Specific Dynamic Ground Response Analysis also notes that for sites considered potentially susceptible to liquefaction, a site -specific analysis is not required if any of these conditions are applicable: • The bridge structure is single -span; • The fundamental period of vibration of the bridge structure is less than or equal to 0.5 seconds; • Only the surficial soil layer is considered potentially liquefiable; • The total thickness of all liquefiable soil layers (excluding the surficial layer) is less than or equal to 5 feet. Multi -span structures will be used for the overcrossing and ramp structures. However, the fundamental period of vibration for the proposed structures is not yet available. The potentially liquefiable soil is within a unit preliminarily mapped as older alluvium based on the previous studies and CPTs performed by Yeh. While older alluvial deposits (Pleistocene age) are typically not considered susceptible to liquefaction due to their age (Caltrans 2020a), additional exploration and evaluation should be performed in future phases of design to whether liquefaction will be a design constraint. A site -specific dynamic ground response analysis may be required for design, in accordance with Caltrans Seismic Design Criteria. The Caltrans Seismic Design Criteria notes that for sites requiring a site -specific ground response analysis, that "the design spectral acceleration at any period shall not be taken less than 80% of the design spectrum obtained from the 2023 USGS Hazard Model with a vs30 =180 m/sec."The design ARS will be provided after a foundation alternatives are selected, additional boring data are available for the site following drilling for the project, and a site -specific ground response analysis is performed (if required). 8.2 OTHER SEISMIC HAZARDS 8.2.1 SURFACE FAULT RUPTURE The project site is not within the Alquist-Priolo Earthquake Fault Zone and is not within 1,000 feet of an un-zoned Holocene mapped fault. Fault rupture does not need to be considered in the design of the interchange improvements per Caltrans Geotechnical Manual - Fault Rupture (Caltrans 2022b). VAPage 447 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 8.2.2 LIQUEFACTION POTENTIAL Liquefiable soil conditions are generally associated with loose to medium dense sand that is below the groundwater table at the time of an earthquake. Older alluvium consisting of loose to medium sand deposits were encountered below the groundwater table in selected previous explorations and recent CPT soundings. The younger alluvium previously encountered in the vicinity of the proposed overcrossing (Parikh 2002) generally consisted of stiff or dense clay and silt sediments that would not be considered vulnerable to liquefaction. Medium dense layers of sand which are potentially liquefiable were encountered in the older alluvium in CPT soundings advanced by WSC (2022) and soundings performed for this project at depths of 44 to 55 feet below the ground surface. A summary of the liquefaction analysis using Cliq (Geologismiki 2025) is included in Appendix A. Liquefiable materials are not likely to impact roadways or surface improvements (other than those adjacent to San Luis Obispo Creek near Madonna Road) but could have an impact on deep foundations for the project. While older alluvial deposits (Pleistocene age) are not considered susceptible to liquefaction due to their age (Caltrans 2020a), additional exploration and evaluation should be performed in future phases of design to ascertain whether liquefaction will be a design constraint. 8.2.3 SEISMICALLY INDUCED GROUND SETTLEMENTS Seismically induced settlements of up to % inch were estimated based analyses using Cliq version 3.5.3.15 (Geologismiki 2025). As a result of the depth of the potentially liquefiable materials, the potential for seismically induced total and differential ground settlement to impact surface improvements at the proposed overcrossing location is considered low. However, deep foundation elements could be impacted by liquefaction induced settlement (see Section 8.2.2). 8.2.4 LIQUEFACTION -INDUCED LATERAL SPREADING Liquefaction- induced lateral spreading is not a consideration for design of the overcrossing and ramp structures based on review of previous data collected at the overcrossing site and the CPT soundings performed for the project. 8.2.5 SEISMIC SLOPE STABILITY The preliminary horizontal coefficients of ground acceleration (kh) for the proposed structures were estimated using procedures described in the FHWA (2011) LRFD Seismic Analysis and Design of Transportation Features and Structural Foundations Reference Manual and referenced in Section A11.5.2 of the AASHTO (2020) LRFD Bridge Design Specifications. The procedures consider the design earthquake, duration, and a tolerable seismic displacement of up to 2 inches. The preliminary design peak ground acceleration for the SEE earthquake used to estimate the horizontal coefficient of ground acceleration (kh) is presented in Section 8.1. Estimated preliminary horizontal coefficient of VA Page 448 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 ground acceleration (kn) shown in Table 3 should be used for preliminary design of abutments and retaining walls under seismic loading. Table 3: Recommended Horizontal Pseudostatic Coefficient for Slope Stability 9. GEOTECHNICAL RECOMMENDATIONS 9.1 PRELIMINARY FOUNDATION RECOMMENDATIONS Foundation alternatives that were evaluated for the proposed overcrossing and ramp structures include spread footings, driven piles, cast -in -steel -shell (CISS) piles, and cast -in -drilled -hole (CIDH) piles. The following are key geotechnical considerations that will influence the foundation design and selection of the foundation type for support of the new overcrossing and ramp structures: • The subsurface conditions at the site generally consist of units of younger and older alluvium overlying Franciscan melange bedrock, as described in Section 4.3. The top of the Franciscan melange bedrock was encountered at approximately 60 feet below the ground surface at the proposed overcrossing location. Franciscan melange typically consists of blocks of harder, more resistant rock within a matrix of softer, intensely sheared and fractured rock. We consider the melange bedrock the likely bearing layer for deep foundations for the overcrossing and ramp structures. • Groundwater at its shallowest depth was encountered at about 10 feet below the existing ground surface near the west side approach to the proposed overcrossing. Groundwater depth appears to vary by location and proximity to San Luis Obispo Creek. Foundation design and construction will need to consider the potential to encounter shallow groundwater. • Layers of lightly to moderately over -consolidated alluvium were encountered near and below the water table, generally from the ground surface to depths of 30 to 40 feet below the ground surface. This unit consists predominantly of soft to medium stiff clay that is considered potentially compressible relative to the expected foundation or embankment loads and could be subject to long-term post -construction settlement. Foundation design will need to consider the bearing resistance of the clay foundation soil and the potential for long-term, post - construction settlement to result in the need for settlement periods or surcharges, downdrag forces on piles, and phasing of a longer bridge construction schedule associated with the approach work. 1A18 Page 449 off 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 • Potentially liquefiable layers of loose to medium dense sandy alluvium were generally encountered at depths of approximately 44 to 55 feet below existing site grades during previous explorations and in the CPT soundings performed for this project. Special recommendations that could be needed for design to address liquefaction include site -specific design response spectra, seismic settlement, negative skin friction on piles, loss of lateral foundation support, and loads on abutments and foundation due to slope instability or lateral spreading. Due to the depth of the potentially liquefiable materials, the amount of estimated seismic settlement and impact to surface improvements such as shallow foundations is considered low (see Section 8.2.2). However, deep foundation elements could be impacted by liquefaction. • Potentially contaminated soil and groundwater has been reported at the site. A plume of Tetrachloroethylene (PCE) was documented by WSC (2022) in the site vicinity. The PCE was present within the alluvium and older alluvium from approximately 20 feet below the ground surface to approximately the contact with the Franciscan melange bedrock. The presence of contaminated soil and ground could require special handling and disposal during construction of CIDH piles or other types of excavation. • This site could be submerged or partially submerged due to the potential for flooding at the proposed overcrossing and ramp locations. Foundation design may need to consider the potential for uplift pressure on foundations, reduced support in the foundation soil, and potential for scour to impact the foundations. The potential for scour to occur in association with flooding has not been assessed at this time. • The site soils are likely not considered corrosive based on laboratory data from previous studies in the site vicinity. The project site is not considered a marine environment based on Caltrans (2021b) guidelines. Steel piles would be designed for appropriate section losses in accordance with Caltrans and AASHTO BDS procedures. Additional corrosion testing will be performed for the Foundation Report during design. • The center bents of the proposed overcrossing structure will be located directly outside the limits of the US 101 mainline. Bents for the ramp structures will also be located directly adjacent to the existing City of San Luis Obispo maintenance yard and Elks Lane. The construction footprint and final layout of the proposed overcrossing foundations may be constrained spatially by the existing facilities for bent construction. Considerations for spatial constraints will likely be needed for both construction and final layout of the proposed structures and foundations. • Existing overhead and underground utilities are present at the proposed overcrossing location that would likely conflict with construction of the proposed overcrossing and would require 17A Page 450 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 temporary or permanent relocation. The exact services and extent of lines that will be in conflict are not known. 9.1.1 CAST -IN -DRILLED -HOLE (CIDH) PILES A cast -in -drilled -hole (CIDH) piles consists reinforced concrete pile cast -in -place within in a drilled hole. Soft ground, groundwater, and other conditions may necessitate the use of drilling fluids and casings during construction and concrete placement for CIDH piles. Design of CIDH piles should consider axial and lateral resistance, initial and post construction settlement of soft clay soil, and the potential for liquefaction of layers within the alluvium. Benefits of the use of CIDH piles as a foundation alternative would include: • CIDH piles can be designed with larger diameters (compared to standard driven piles) to provide additional axial or lateral resistance, or to reduce the total number of piles needed; • A single CIDH pile can be designed with a structural connection to a bridge column without the need for a pile cap (and associated excavation); • CIDH pile installation is generally considered to have less vibrations and noise associated with the drilling as compared to the pile driving. • CIDH piles can be designed to develop higher capacities in hard or dense bearing material where a smaller-, standard -size driven pile may have a limited capacity and meet refusal near the surface of the bearing material. The anticipated bearing material is the Franciscan melange bedrock encountered at approximately 60 feet below the site. CIDH piles need to be embedded a sufficient depth into the rock to provide the needed axial and lateral resistance for the design loads; and • CIDH piles can be designed to provide resistance to scour as well as downdrag forces from both consolidation and liquefaction, if needed. Constraints of the use of CIDH piles as a foundation alternative would include: • Wet methods (slurry displacement) would likely be needed to construct CIDH piles because of the groundwater elevation encountered in the previous borings at the project site. Drill rigs used to construct CIDH piles can be equipped with temporary casings and other tooling to help support the shaft during drilling and advance the hole through soft ground, caving soil layers, and groundwater. Post -construction inspection and non-destructive testing of CIDH piles constructed in the wet is required by the Standard Specifications. Anomalies are often identified that require delays, review of the design loads, and possible mitigation or pile replacements to address anomalies; VAPage 451 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 • Tanks for slurry and spoils associated with wet -method CIDH pile construction can require a larger construction footprint compared to driven piles; and • CIDH pile construction would involve cutting and slurry disposal that would likely encounter groundwater conditions and potentially contaminated soil that would require special handling and disposal. CIDH piles are considered a feasible foundation support for the proposed overcrossing and ramp structures. CIDH piles would likely be designed to develop resistance to axial loads from the portion of the shaft embedded in the Franciscan melange. Drilling within the Franciscan melange will likely be variable due to the presence of harder, more resistant blocks within the melange. 9.1.2 DRIVEN PILES Driven piles typically consist of Caltrans standard plan steel pipe or square precast concrete piles or nonstandard H-piles. Design of driven piles should consider axial and lateral resistance, initial and post construction settlement of soft clay soil, and the potential for downdrag forces to develop within compressible layers of the alluvium or potentially liquefiable layers. Driven piles were used for a portion of the widening project at US 101 and Los Osos Valley Road (MNS 2015). Benefits of driven piles as a foundation alternative may include: • Driven piles extending below the groundwater level may have less construction challenges than drilled methods below the groundwater table; • Driven piles could reduce the amount of excavation within contaminated soil and groundwater (if pre -drilling is not needed) as compared to cast -in -drilled -hole (CIDH) piles; • Driven piles can be coated with friction reducing coatings which would lower downdrag loads from liquefaction and consolidation settlement resulting in higher net individual pile capacities; • Driven piles would not require slurry or cutting disposal (if pre -drilling is not needed); • Steel pipe piles or H-piles can be cut off or spliced to accommodate variations in pile length in relation to variable depth to bedrock, if encountered during pile driving; and • Driven piles can be designed to provide resistance to scour as well as downdrag loads, if needed. Constraints of the use of driven piles as a foundation alternative would include: • Hard driving conditions could be associated with denser layers within the older alluvium or within the Franciscan melange encountered in previous studies within the site vicinity (i.e., the refusal depth encountered within the CPT soundings). Franciscan melange bedrock may I � Page 452 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 have variable driving conditions based on the presence of harder, more resistant blocks within the formation. These conditions may result in the need for pre -drilling for pile installation, if needed to penetrate within the Franciscan melange to achieve the needed axial and lateral resistance. If driven piles are used to avoid excavation of contaminated soil and groundwater, pre -drilling would likely not be allowed or special considerations for spoil disposal might be needed. Pre -drilling will likely encounter groundwater and generate wet, clayey cuttings (and potentially encountered contaminated soil) that will need to be handled and disposed of. • Closed -end or displacement type piles (such as concrete piles) would likely result in harder driving conditions and more likely pile refusal compared to open-ended or non -displacement type piles (such as H-piles). Open end pipe or H-piles may run during driving, resulting in an uncertain pile tip elevation and driving conditions during construction. Close -end pipe piles would help to control the pile tip elevation for design and construction. However, H-piles may be more cost effective and could be used provided there are provisions in the project specifications to account for the conditions noted above; • If the lateral pile resistance is limited within the alluvium, battered piles could be used to provide additional lateral resistance. However, other stiffer pile types (such as cast -in -steel - shell or cast -in -drilled -hole piles) may be needed to provide additional lateral resistance. • Driven piles would need to be driven into the underlying bedrock that was encountered about 60 feet below the existing ground surface elevation and could require pile splicing. Pile driving could be delayed if splicing of steel piles is needed because of requirements for inspection and testing of field welds; • Pile driving will generate noise. The duration and impacts of pile driving should be considered relative to the proximity of the site to downtown, local businesses and residents, and San Luis Obispo Creek; • Pile driving vibrations attenuate away from the foundation location relatively quickly. However, pre -construction condition surveys of nearby buildings, video and photo documentation, distress surveys, and noise and vibration monitoring during pile driving should be performed prior to pile driving to help document baseline conditions for historic structures, nearby buildings or residences that may be impacted by pile driving and whether they were impacted by the construction; • The clay alluvium could be prone to setup when driving is stopped and could require higher driving energies to restart the pile after driving resumes; • A group of driven piles would likely be needed to support structure loads above the standard pile capacity for single piles. A group of piles would need a pile cap for structural connection between the foundation and superstructure. Pile cap excavation and construction for the 17A Page 453 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 driven piles could include shoring, subgrade stabilization, and/or dewatering depending on the final depth of the excavations within the alluvium; and • Pile caps for driven piles could require a larger final design footprint compared to large - diameter CIDH piles connected directly to the structural column. Driven piles are considered a feasible foundation support for the proposed overcrossing and ramp structures, and could be preferred for the project depending on final layout and loading conditions as well as the need to avoid excavation within contaminated soil or groundwater. The piles should be driven at least to Franciscan melange bedrock and consider potential lateral forces and additional downdrag associated with settlement and liquefaction, if needed. 9.1.3 CAST -IN -STEEL -SHELL (CISS) PILES CISS piles typically consist of driving a steel pipe pile into the ground and casting reinforced concrete into the head of the pile to form a structural connection to the superstructure. The concrete can be placed in a closed -end pile, or by removing a portion of the soil plug within an open-end pipe pile to allow for concrete placement. Design of CISS piles should consider axial and lateral resistance, initial and post construction settlement of soft clay soil, and the potential for liquefaction of layers within the alluvium. Benefits of the use of CISS piles as a foundation alternative would include: • Larger diameter CISS piles are commonly used to resist lateral loads for relatively large structures and may be preferred over standard steel pipe piles if a larger lateral resistance is needed to satisfy special structural considerations or loading conditions; • CISS piles can be coated with friction reducing coatings which would lower downdrag loads from liquefaction and consolidation settlement resulting in higher net individual pile capacities; • CISS piles can be designed to resist scour as well as downdrag forces from both consolidation and liquefaction and could provide greater resistance to liquefaction -related effects than standard piles, if needed; and • Steel pipe piles for CISS piles can be cut off or spliced to accommodate variations in pile length in relation to variable depth to bedrock, if encountered during pile driving. Constraints of the use of CISS piles as a foundation alternative would include: • Hard driving conditions could be associated with denser layers within the older alluvium or within the Franciscan melange encountered in previous studies within the site vicinity (the refusal depth encountered within the CPT soundings). Franciscan melange bedrock may have 17A Page 454 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 variable driving conditions based on the presence of harder, more resistant blocks within the formation. These conditions may result in the need for pre -drilling for pile installation, if needed to penetrate within the Franciscan melange to achieve the needed axial and lateral resistance. A closed end pile could likely not be driven to the design tip elevations without pre -drilling; • CISS installation using an open-end pipe pile would involve disposal for the soil plug. Groundwater was encountered at about 10 feet below the ground surface at its shallowest point. If the plug needs to penetrate contaminated soil or groundwater, special handling and disposal may be required; • CISS piles are typically more costly than CIDH piles or standard driven pile foundation systems, depending on the load demands and structural considerations; • Pile driving will generate noise and vibration. Pre -construction surveys of nearby residences, distress surveys, and noise and vibration monitoring may be needed for pile driving; • CISS piles would need to be driven into the underlying bedrock that was encountered about 60 feet below the existing ground surface elevation and could require pile splicing. Pile driving could be delayed if splicing of steel piles is needed because of requirements for inspection and testing of field welds; • The clay alluvium could be prone to setup when driving is stopped and will likely require higher driving energies to restart the pile after driving resumes; and • A group of CISS piles will likely be needed to support structure loads above the standard pile capacity or to provide a structural connection between the foundation and superstructure. CISS piles are considered a feasible foundation support for the proposed overcrossing and ramp structures. CISS could be preferred over CIDH piles if higher lateral load demands are needed. The piles should be driven at least to Franciscan melange bedrock and consider potential lateral forces and additional downdrag associated with settlement and liquefaction, if needed. 9.1.4 SPREAD FOOTINGS Design of spread footings should consider bearing resistance as well as initial and post construction settlement of soft clay soil. Benefits of the use of spread footings as a foundation alternative would include: • Potential reduced cost of construction compared to other foundation methods, if footings can be constructed in the dry without excessive shoring, ground modification, and dewatering, and • Spread footings are a conventional foundation type. Specialty contractors are not typically required for construction. IF 24 Af Page 455 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 Constraints and considerations that could adversely impact the cost and feasibility of supporting the proposed overcrossing and ramp structures on spread footings foundations include: • Long-term settlement and consolidation within clay layers could require pre -loading, settlement waiting periods, or ground modification to support anticipated foundation loads, • Ground modification may be needed to mitigate settlement or strengthen the alluvium to provide adequate support for spread footings; • Spread footings would provide less lateral resistance to seismic loading than deep foundations; • Dewatering, shoring, and subgrade stabilization would likely be needed if footings are to be constructed below groundwater; • Special handling and disposal would be needed if excavations encounter contaminated soil; and • Shoring with adequate lateral support systems may be needed to limit the footprint of footing excavations to avoid potential impacts to US 101 as well as other existing facilities and utilities that may be present in the vicinity of the work. Spread footings are not recommended for preliminary design of the proposed overcrossing and ramp structure foundations based on the preliminary analyses and review of previous and current study geotechnical data. Spread footings would likely not allow for tolerable settlement under the design service loads without some type of ground improvement to reduce the potential for short and long- term settlement of the alluvium. The alluvium may also require ground modification below the footing area to be able to support the anticipated design loads for the structures. The design and construction of spread footing foundations may be relatively complex and could include risks for unanticipated costs associated with disposal of excavated clay soil, contaminated soil, shallow groundwater, and spatial constraints. 9.1.5 PREFERRED PILE FOR DESIGN CIDH piles embedded below the compressible and liquefiable layers (if present) and bearing within the Franciscan melange bedrock at the site are considered the most suitable foundation support for the proposed overcrossing and ramp structures. Preliminary factored nominal axial pile resistance versus CIDH pile embedment depth into the underlying Franciscan melange bedrock for the Strength Limit state is presented in Figure 5 for various pile diameters. The axial pile resistances provided in Figure 5 include contribution from side resistance but neglect contribution of end bearing resistance. The pile resistances provided in Figure 5 should not be extrapolated outside of the limits provided. CIDH pile embedment depths into the Franciscan melange bedrock will depend on the loads from the structures as well as any loading due to downdrag (from consolidation settlement or from 1A f 1 Page 456 of 059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 liquefaction settlement if occurs, as noted in Section 8.2.2). These values will need to be updated based on data obtained from additional field work and laboratory testing anticipated for the project (see Section 10). Driven piles or CISS piles are also considered feasible alternatives, but may have limitations as noted above. Driven piles should preliminarily be embedded to at least the top of the Franciscan melange bedrock. Embedment within the Franciscan melange will likely be variable due to the presence of harder, more resistant blocks within the melange. Piles may need to be ordered longer than the preliminary recommended embedment elevation to account for variability of the melange. Preliminary axial pile resistance and embedment will likely be controlled by the structural capacity of the pile. Pile loads will need to consider the loads from the structures as well as any loading due to downdrag (from consolidation settlement or from liquefaction settlement, if it occurs, as noted in Section 8.2.2). Driven pile embedment recommendations should be updated based on the data 4 Y v 0 X 0 L Q a 0 C ar E -0 ar E W 0 10 20 30 40 50 60 70 80 90 100 110 120 Preliminary Factored Nominal Axial Resistance (kips) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 Min. 10' Embedment into the Franciscan Melange (KJfm) ` L NOTES: 1. Franciscan melange (K)fm) bedrock encountered at approximately 60 feet below the ground surface in the site vicinity based on previous studies. 2. Preliminary factored nominal axial resistance versus embedment depths shown were estimated according to the latest Caltrans (2019) Amendments to the AASHTO (2017) LRFD Bridge Design Specifications for the Strength Limit state (resistance factor of 0.7) and Extreme Limit State (resistance factor of 1.0). These values do not include the effects of static or seismic downdrag, lateral pile capacity, or group efficiency. 60-in. Dia. CIDH - Strength Limit State 72-in. Dia. CIDH - Strength Limit State 84-in. Dia. CIDH - Strength Limit State 96-in. Dia. CIDH - Strength Limit State 108-in. Dia. CIDH - Strength Limit State 4,000 4,500 5,000 3. Pile embedment depths limited to a depth of approximately 30 times the diameter of the pile for constructability. Limiting pile depth includes approximate depth to bedrock plus embedment. ---- 60in. Dia. CIDH - Extreme Limit State 72-in. Dia. CIDH - Extreme Limit State 84-in. Dia. CIDH - Extreme Limit State 96-in. Dia. CIDH - Extreme Limit State 108-in. Dia. CIDH - Extreme Limit State Figure 5: Preliminary Factored Nominal Axial Pile Resistance versus Embedment Depth into Rock IA 26 Page 457 of 1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 obtained from additional field work and laboratory testing anticipated for the project (see Section 10). 10. ADDITIONAL FIELD WORK AND LABORATORY TESTING Subsurface exploration, laboratory testing, and analyses should be performed in preparation of the Geotechnical Design Report (GDR) and Foundation Reports for Earth Retaining Structures (FR for ERS) and structures (FR) for the project. The design -level field explorations will be checked and modified for the selected design alternatives. The future field exploration program will supplement the CPT soundings performed in July 2025 and include drilling vertical borings at the proposed overcrossing and ramp structure supports, retaining wall locations (where applicable), pavement areas, infiltration basin areas, and proposed overhead sign structures. The types and numbers of tests may vary based on the results of the field exploration program. 11. LIMITATIONS Yeh prepared this report for Consor and their authorized agents only. It is not intended to address issues or conditions pertinent to other parties, projects or for other uses. This report is for preliminary planning purposes only and is not intended for use in final design or construction. The results of this study are preliminary and subject to change pending the results of our design -level field exploration and geotechnical evaluation. No services have been performed to evaluate environmental impacts, or the presence of hazardous or toxic materials. Site conditions will vary between points of observation or sampling, seasonally, and with time. The nature and extent of subsurface variations across the site may not become evident until excavation is performed. If during construction, fill, soil, or water conditions appear to be different from those described herein, Yeh should be advised and provided the opportunity to evaluate those conditions and provide additional recommendations, if necessary. 12. REFERENCES American Association of State Highway and Transportation Officials (AASHTO 2022), Guide Specifications for Bridges Subjected to Tsunami Effects, issued 2022. American Association of State Highway and Transportation Officials (AASHTO 2017), AASHTO LRFD Bridge Design Specifications, 8t" Edition, issued 2017. Arcadis (Arcadis 2019), Well Destruction Report; Chevron Site No. 306466, 300 Block of Elks Lane, San Luis Obispo, California, CCRWQCB Case No. SLT3S569, dated June 6, 2019. California Department of Transportation (Caltrans 2025b), ARS Online v4.0, website, accessed June 24, 2025, https://arsonline.dot.ca.gov. �� Page 458 off1059 DRAFT Structure Preliminary Geotechnical Report — Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 California Department of Transportation (Caltrans 2025a), Seismic Design Criteria Version 2.1, issued January 2025. California Department of Transportation (Caltrans 2024b), Geotechnical Manual, Foundation Reports for Bridges, issued July 2024. California Department of Transportation (Caltrans 2024a), Standard Specifications, Sacramento, California, issued 2024. California Department of Transportation (Caltrans 2023). U.S. 101/Prado Road Interchange Project, on U.S. 101 in San Luis Obispo County, 05-SLO-101-PM 26.5-27.3, Project ID Number 0516000105, Initial Study with Proposed Mitigated Negative Declaration, dated January 2023. California Department of Transportation (Caltrans 2022b), Geotechnical Manual, Fault Rupture, Sacramento, California, issued October 2022. California Department of Transportation (Caltrans 2022a), Geotechnical Manual, Site -Specific Dynamic Ground Response Analysis, dated March 2022. California Department of Transportation (Caltrans 2021b), Corrosion Guidelines, Version 3.2, Division of Engineering Services, Structure Design, issued May 2021. California Department of Transportation (Caltrans 2021a), Geotechnical Manual, Design Acceleration Response Spectrum, dated January 2021. California Department of Transportation (Caltrans 2019). California Amendments to the AASHTO LRFD Bridge Design Specifications, Eighth Edition, Sacramento, California, issued April 2019. California Department of Transportation (Caltrans 2001), Field Review Memorandum, 05-Og780K, 101-SLO-PM27.0/27.5, Auxiliary Lane, dated July 23, 2001. California Department of Transportation (Caltrans 1986), Pile Quantities and Driving Records, Bridge No. 49-185, dated October 2 to 10, 1986. California - Department of Public Works - Division of Highways (Caltrans 1963), Log of Test Borings, Madonna Road Overcrossing, Bridge No. 49-190, as -built sheet, dated January 8, 1963. California - Department of Public Works - Division of Highways (1962), Pile driving records, Bridge No. 49-190, dated October 1, 1962. California - Department of Public Works - Division of Highways (Caltrans 1961b), Log of Test Borings, Los Osos Road Overcrossing, Bridge No. 49-185, as -built sheet, dated December 12, 1961. California - Department of Public Works - Division of Highways (Caltrans 1961a), Pile driving records, Bridge No. 49-185, dated October 2 to December 4, 1961. Consor (2025b), Strip Map, provided via email December 5, 2025. �� Page 459 off1059 DRAFT Structure Preliminary Geotechnical Report - Overcrossing Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025December 23, 2025 Consor (2025a), Strip Map Profile, provided via email December 3, 2025. Dokken Engineering (Dokken 2009), Technical Memorandum, Seismic Evaluation, U.S. 101/Los Osos Valley Road Interchange Improvements Project, San Luis Obispo, California, dated January 22, 2009. Fugro West, Inc. (Fugro 2002), Geotechnical Report, City of San Luis Obispo Water Reuse Project, San Luis Obispo, California, Project No. 01-52-0721, consultant report prepared for Brown and Caldwell, dated April 2, 2002. Fugro West, Inc. (Fugro 1999), Geotechnical Engineering Report, Laguna Lift Station Force Main Upgrade and Replacement Project, San Luis Obispo, California, Project No. 99-42-0411, consultant report prepared for Brown and Caldwell, dated November 23, 1999. Geologismiki (Geologismiki 2025), Cliq Liquefaction Analyses Software v3.5.3.15, release date June 3, 2025. GeoResearch-Unocal (GeoResearch-Unocal 1990), Site Investigative Report, Elks Lane and San Luis Obispo Creek, San Luis Obispo, California, dated April 16, 1990. G H D (GHD 2018), Project Study Report - Project Development Support (PSR-PDS) to Request Approval to Proceed to the Project Approval and Environmental Document Phase for a Locally Funded Project on Route 101 between 0.3-mile south of Prado Road and 0.2-mile south of Madonna Road Overcrossing, EA 05-1H640K, dated March 2018. MNS Engineers, Inc. (MNS 2015), Pile driving records and quantities, Bridge No. 49-185L, dated February 3 to 16, 2015. Parikh Consultants, Inc. (Parikh 2002), Log of Test Borings, Route 101/Prado Road Overcrossing, last revision dated November 15, 2002. United States Department of Agriculture, Natural Resources Conservation Service (NRCS 2025), Web Soil Survey, "San Luis Obispo County, California, Coastal Part (CA664)", accessed June 23, 2025, available online at http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx Unites States Department of the Interior - United States Geological Survey (USGS 2025). Earthquake Hazards Program, Interactive Fault Map and Quaternary Fault and Fold Database of the United States, accessed June 28, 2025, https://www.usgs.gov/programs/earthquake-hazards/faults?qt- science_support_page_related_con=4#qt-science_support_page_related_con United States Department of Transportation - Federal Highway Administration (FHWA 2011), LRFD Seismic Analysis and Design of Transportation Geotechnical Features and Structural Foundations Reference Manual, Geotechnical Engineering Circular No. 2, NHI Course No. 130094, Publication No. FHWA-NHI-11-032. 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(Yeh 2025), Foundation Report, Caltrans Bridge No. 49C0107, Prado Road Bridge Replacement at San Luis Obispo Creek, San Luis Obispo, California; Project No. 216-323, consultant report prepared for the Wallace Group/City of San Luis Obispo, draft report dated November 25, 2025. VA 30 A Page 461 of 1059 f� 1 •� x z g C? r • Q a •'-' d o m o :iw a Uj .� W Q ory L(jjj y i. o .. c 1? C O z N z ry qw s =C. .. r> d� N c Z pj i \ V N ry C Z I a O MID tol �Q N '• J!�. 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N M O o � V Q 4- 0 rn CD N ^(B LL Yeh and Associates Yeh and Associates, Inc. https://www.yeh-eng.com Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-01 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance 6 --- --- 8------- -------- 10 -------------- 12 ------ ------- 14 ----- ------- 16 ----- ------- 18 ----- ------- 20 ...... ........ 22 ------ ........ 24--------- ti------------ 26 - 28 --------------.......- L 30-------- ------- 32 ------ -------- QJ 34 ------------------------- 36........ ........ 38 ---- ........ 40 ------- 42 -- ------- 44 -- ------- 46 --- ------- 48 ------- 50 --- --- 52 --- ------- 54 - ------- , 56 ' 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 CRR plot 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 0 200 400 0 2 4 6 8 10 1 2 3 4 0 qt (tsf) Rf (%) Ic (Robertson 1990) Mw=71/2, sigma'=1 atm base curve 0.8 0.7 0.6 u 0.5 0 0 0.4 Ln (V V) u_ 0.3 v U 0.2 0.1 0 H/J JD AUGERM ------------- ag•earthgq} .. M to C] r 0 (] I` IZT Cn cB n Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 FS Plot HANDAUGER �Jb 0.2 0.4 O.E 0 0.5 1 1.5 2 CRR & CSR Factor of safety Summary of liquefaction potential 1,000 , I I I I I I I I I I 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction ............... .... ..... �. 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Y0 C 5 N U m m rn o E mo'w_ rn i j 3 L � ; V •C ��pp N 49 ui V v c o N in o T W W O w w N o m o C Z Z co IZ O . -I p O C OLn 0 w w— U,c CE C O O O m m N E (/1 V l0 a) C f6 E CDy � u oSm°S V C C S O m N 0 F.I Q LLO_ W 0_0 0, N Q O O U aJ 6 Yeh and Associates Yeh and Associates, Inc. https://www.yeh-eng.com Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-02 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance Friction Ratio SBTn Plot CRR plot 0.8 0.7 0.6 u 0.5 0 0 0.4 aV Ln u_ 0.3 v U 0.2 0.1 0 5 10 15 20 25 30 35 40 45 50 55 60 Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based FS Plot 5 10 15 20 25 30 35 40 45 50 55 60 100 200 30( 0 2 4 6 8 10 1 2 3 4 0 0.2 0.4 O.E 0 0.5 1 1.5 2 qt (tsf) Rf (%) Ic (Robertson 1990) CRR & CSR Factor of safety Mw=71/2, sigma'=1 atm base curve Summary of liquefaction potential 5 10 15 20 25 30 35 40 45 50 55 60 1,000 QJ .N v 100 0 v c v a F v v to N M E 0 Z 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction ��.., • Wo Liquefadtion Project file: C:\Users\jking\Yeh and Associates, Inc\223-400 Prado Road IC - General\3.2 CPT\223-400 Prado Road IC Liquefaction CPT-01 to 04. q age 477 of T059 A-12 of 32 fV O d V E ra uV d a H 7 O m s d m .O U) 41 O a m O o a e yO V LL g -- --- -- ........ 6 ...... --em s _ ....... cfi..........�; r ea••;---; rrv-- -- ---Y-S zi �-z; -- dtf- o2f - .$ d3 :.6:.6.6: .6 as de$d n :0 ; 00 (-X-) U ; c-), 0 ; CX-)X-X-XX-)cXx..) cx-)c-) C N O N V- ID W O N V- 10 M O N V 7 10 W 0 N V 10 W 0 (lj) 4adaa J N 7 iD W O V O O N N N N 0m m M M m 0 cNY c-h M- R VNl lR v01 R rq ()j) 4ada4 O N -;r O OD O .N-i .�-i l0 W O N N lD OJ O M M M O 1- 'D W O V) t- lit) m a0o io (41) 4adaa .4- 10 W D N N IDW M M M M M 7 "V V w � � 14- to w l00 lN0 W 10 ti �00 �o) fa o � O o � F 7 m U) M N O N a v s� r, oo ' of ■■❑ ±' C T � � O O p a c C N C A N C �O N U in u 7 ' L!) 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(earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance Friction Ratio SBTn Plot CRR plot I Y a QJ 0 0 ----- --- ---- 2 -- ---- --- 4 ..... .... 6 ---- ---- 8 --- ---- --- 10 ... ..... .... 12 ... ..... .... 14 -------------------- - 16 --- --- 18 -- ---- --- 20 .... ..... 22 ---- ----- ---- 30 ---- ----- ---- , 32 , , 36 -- ----- ---- 38 --- ---- --- 40 ... ..... .... 42 .. ...... 44 ----------- 46 --- --- 4g ..... .... 50 ..... .... 52 ---- --- 54 ---- --- 56 ---- --- 58 ---- --- 60 0.8 0.7 0.6 U 0.5 0 0 0.4 Ln (V V) u 0.3 T U 0.2 0.1 0 4 ----------- 6 ---- - -- 8 10 .. 12 .. 14 16 18 20 . 22 ' , 30 32 . 36 - ---- - 40 .. 46 ---- -- 48 . 50 52 54 ' 56 58 60------------ 100 200 0 2 4 6 8 10 1 2 3 4 0 qt (tsf) Rf (%) Ic (Robertson 1990) Mw=71/2, sigma'=1 atm base curve 1,000 QJ .N v 100 0 v c v a F U v to N M E O Z Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based FS Plot 0.2 0.4 0.E 0 0.5 1 1.5 2 CRR & CSR Factor of safety Summary of liquefaction potential 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction ............... .... 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O,y a O 00 O 10 0 .0.................. ---------------------- ...... -- ------ N O 00 Il 11� Ul V M N O O O O O O O O O (.bS7)) Oiled SSaa;S ollo/1J 0 0 0- o -+ ~ aouelslsaa uolaealauad ldD paZllewaON 0 fa M M LO OCD O 00 IZT T � O O O m o ¢ o Z} }InZZ U c o v o N W� a a cu r m U •rj 3m o�EE N I L Y um J M O Lr Q N O U) N O CD M a U O O w Q ^ N 7 rV mZZ 02 -0 m c R aao m Oa N= w U 1 K momu o rn Svow_rn �o av �= O� oa>>�»u: UN c � U N E 49 O A O Lp WW > N H V v c ¢ v079 1 T w W CDw w N O m 0 0 N s � v Q� 3C A J O1 O O C C G7 d U L NC E c u G �O C V lAr-I O m �p E V �p M U o E m Y�3 ui V > V C C O m N 0 O fr ¢ wa wa0 U a O O N 7 ID 00 O .Nr .fir N N N N N M M M M 7 7 7 7 Ln L 10 00 t00 (1j) yjda4 x d V e _ fr O H � m O N 1-0 O L � V OC A CL L O O O y C s c V o N 7 10 w O 'D m O N 'D w O N 7 'D 00 O N 7 t0 00 O N 7 tD 00 O N N N N N M M M M M 7 7 7 7 7 m m � t0 O L L i O u W m w v � � V s S U M D N V, ID w (U) y}daa N �r 'D m o O N tD OD 0 .Ni ti „may w N N N N N M M M M V V V �N+t v�i voi O 0 M O 61 N � O � Cl 0 CD N 0 w Q O Q O N N 10 Z} }In ZZ U c w o a a a o. m o O 'Q cu 6 U r m �. O m ,O _ w o w •� L d Y -Q -p 01 c� 3 m I L Y U J J M D Lr N Li O N u) O r a itf M U O o w Q v,o ^ N v)r4 mZZ p i U m C m a, L Lf, aaw m Oa w = O V K momu o rn +Jwow_2) O Q N V •- 0l = 0 � 0 Q i-Vi lL N c N V w �ti O 49 (p WW > N Y � � m Nl V v C o in o Ov1 T wwT� (Dw o m 0 w N 0 co N s 3C � Q � J O O O c C L t o -o G7 d NC c u uw G 78 cc m O �0 V O M. r-I +L' vl -O o E u i t5 UI O yV j Oi +g M Iti y V > N L Y > V c c m C C O N 0) A Q wD_ wo_0 p U Q- Yeh and Associates Yeh and Associates, Inc. https://www.yeh-eng.com Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-04 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance 6-------- 8 -- ---- --- 10 --- 12 -- ---- --- 14 - ---- --- 16 ------ 18 ..... ................. 20 ----- 22 .. ..... .... 26 ' 28 30 ... ..--- L 32 , a 36 -- ---- --- 38 -- ---- --- 40 ..... ................ 42 --- ................... 44 - ----- 46 ................. 48 --- - ... 50 --- --- 52 ... ------------ 54 .... --- 56 58 ----------- 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 CRR plot 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 HAi Ju AUGER ----------------- ag eartk. - M to C] r 0 r CI) IZT Cn M n Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 FS Plot HANDAUGER 0 100 200 30C 0 2 4 6 8 10 1 2 3 4 0 0.2 0.4 O.E 0 0.5 1 1.5 2 qt (tsf) Rf (%) Ic (Robertson 1990) CRR & CSR Factor of safety Mw=71/2, sigma'=1 atm base curve Summary of liquefaction potential 0.8 0.7 0.6 u 0.5 O 10 0.4 Ln Ln u 0.3 v U 0.2 0.1 0 1,000 QJ .N v 100 0 v N Q F a U -0 10 E 0 Z 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction �•�iiILO Wo Liquefadtion CLiq v.3.5.3.15 - CPT Liquefaction Assessment Software - Report created on: 7/30/2025, 3:02:29 PM 15 Project file: C:\Users\ king\Yeh and Associates, Inc\223-400 Prado Road IC - General\3.2 CPT\223-400 Prado Road IC Liquefaction CPT-01 to 04.clq A-26 of 32 m �, �n ......................... T.__ --------------- 7 ob _ , — 0) z �--- -`- "_:___:___:ray----;0-- - ---rnMc-:-vx <Ti '6 = ks %---•'---' - x ; otf o2$ atSco co S"ot3" - -��---�..�a. .ram....;...' ;----'�'�•�'-�-c�d:-m-�- ~ iEoux) CD Uc»c�U) UX/J� Ua U)U) C/J U� --- --- --- '_- --- --- ' UJ F - 7 M N O O N V m m O .N-i .�-i .O-i m O N 7 %D m O N 7 to O O N 7 ko M c -;r %D m N N N N N M M M M M V V 7 (4j) 44da4 v M m N iD O O N tD m O N "4 N N (41) y�da4 a c i a O C N r< 0616 ■■❑ a +' C T � � O O O a V C T N TO N U in U 7'ui O MEN C y a) a> E L u O C .0 > A Ln O V ,y N M ❑ ❑ ❑ T C al a) An Z} }ZOZ 3 H _— o a rov�ao rn._ - ar a) a) v .N [1 Y a a ............... __ ________ ___ _ _ __ _ __ __ ____ ___ O ILL Y U (�) 4ada4 m M � o O a Imo co •y Ln N Z Z Ln N Q O C o R Li 3 N > u ' 01 i 4 al O �O m O .N. v io m o N v o m o N 7 io m o N 't io m O N T io m p p a j j Li N N N N N M M M M M V V V V V N V1 V1 V1 N (�) yadaa ____ _ ________ ___ ____ _ ______ _ ____ ___ ________ ____ ___ ________ ___ ____ ___ ____ _ ___ ___ _ _ _ ___ __ _ CD O > M Ln C 0 T w W 78 O unf M ...................................... p o w w N o M LA H 9 .. d . 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N C O N CO 9 �1 iu 5 t moo, u p Y L In Y N V O O N Y O c G E u Q E V Q > J Q CD LL ■■❑■■ Li Ln c � o C) 'a v)rV mZZ t v R C v L o C U 2 �p f6 O m E U1 f v � ; V •C OQ ti ��lL 49 ��pp N to H Vv0 0 T ww78 o W w N o m o U U zzm, cs vi c �o.. 10 o_ c_ L G1 IS " � N w w— N c C U 45 o o. '�mv Ev m o E Y 0 3 +, �oS�°S V C C r O N 0 M Q w d Wm d 0 m J 0 ci; .N. ... ............. ... .... ... ... . y --. ... ... .. _. o� C... ............. ... .... ... .... _ • �•• _ ... • A ID > QQ • O ______________a______._......._ _____ _�........ ------- ...... O N iiti•i.••�•N .•�1~�•�I.�J• v+if1iMf@11a1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 N O pi of 1� t0 ui 7 M N .y O .. .. ~ (w) ZH 'JaAej pues ajgeijanbij;o ssauloigl ----------------- N C V O7 w .r N 0 ________________________________... ..... __________ -------------------- ______ Q J O O O N O U a O 00 O .� W O 00 Il O ul V M N O O O O O O O O O (.'dS7)) Oiled SSaJ;S 711J/1] 0 0 aouelsisaJ uoiaeJlauad ldD paZI12WJON 0 0 fa 0 N M LO OCD _ r M � O CD c T � O O O Z. ¢ o Z} }InmZZ U c o v o N W� a a cu r m U 01 O _ Y N N 01 Q _ -o a $ � o� I L Y U J J L!1 0 T N O u) N O cD M a U O O Q ^ N 7o v)rV mZZ 02 c a m O a v� �ou mou o rn ..vow_rno f cn�3wL o c �C U N C49 ti 2 (p Go Go > N T w w O w w N O m 0 0 zzm�o,Lm w m N s cm � v Qm 0� -o � O U GCJE C V +� ' U�1 G � C V Ln O O m �p � r-I � i +L' vl -o �p M U o E � YC3 ui 2 co C C� O m N 0 O fr Q wa wa0 U a 0 O M O N � O � O O O N 7 a0 W O Ny .fir .Wi N N N N N M N A M 00 7 7 V- 7 00 lNtl q- %D 00 L � U MA y L L +� O O CL y c s o� V W 00 O N 7 10 W O N t0 W O N t0 W O N 'D W CD V l0 00 N N N N m M M O L _ _ ___ _ O +�+ . W __ ____ ___ _ _ J. s � . . . . . . . . . . . . . L l0 O O N 7 a0 00 O N 7 a0 OD O N 7 l0 00 O N I- t0 00 O N 7 %D W vIu (M) 4jda(i 10 W O V- .10+ N N N N CD m M M M M V V V V V 't v�i ()}) yjdaa V, O rn M 0) c O N N � U N O C V Q N Z. Z } } conon Z Z U O � a v .Q .Q 0! a o. m m a t O ) O1 > D d J 'm�O O L Cm � dam. O 0 F V a T O A C I L Y U J J 0 O H U) W c 0 o a 0 0 y 7 rV mZZ Ln Y t •m M a °.�' Y0 C 5 N U m m rn o E mo'w_ rn -C j 3 E L tieV •C -V-. O N N @ ^ O i> > U1 V v C o � T w w 78 CD w N o m o UU m "M vi C Z Z m ri O 10 O C �o 3C O_ C_ V L L - i O N W 9 •�_• C� CV c O O MO) 0 i 4jE /1 V l0 f6 E o C u$ o o° S 0 V L y i m C c o w 0 M Q LL LL w d 0 APPENDIX B — RELEVANT PREVIOUS DATA Page 498 of 1059 Jlt, BRIDGE DEPARTMENT rl kt Ti � J:t -MT 1, x T—i L1 f T k zo A, th Ed.' M%W www"x wso%, -40�— 0 n r-7 jc m -In V) 4— • a t r! 339 '3M MIYW N° NOLLYf1M1N00 d W r• ..�\ N63'60'O6.E J♦t0 ]♦. .. .. .. ".... .. t a Jm i:l. 64.41 a Z C 3 a • ry0�� 6� U y 0�0 I S n W c y � I O � ` o ♦ � m C • 6 n ♦ O m m OD n_ ... � x OD OD cr a aEE o ♦\ o I ' • a j 8 j' o Of o O a. W OD i i ;• \ .o O f37.23 .,..wwuro•✓r a -role=............. LO C) O C) O LO O a- November 1999 Project No. 99-42-0411 . GRO E E LOCATION: The drill hole location referencing local o E� Z w j landmarks or coordinates General Notes r F W m J d O SURFACE EL: Using local, MSL, MLLW or other datum o N Soil Texture Symbol w N m w MATERIAL DESCRIPTION Sloped line in symbol column indicates • transitional boundary Well graded GRAVEL (GW) 0 1 25 Samplers and sampler dimensions (unless -12 2 otherwise noted in report text) are as 16, Poorly graded GRAVEL (GP) follows: -14 4 , 2 ;' (25) O Symbol for. A 1 SPT Sampler, driven Well graded SAND (SW) R 34.9 mm to, 50.8 mm OD S 2 CA Liner Sampler, driven -16 67 E 60.3 mm ID, 76.2 mm OD 3 (25) Poorly graded SAND (SP) G 3 CA Liner Sampler, disturbed -18 8 I I A . 60.3 mm ID, 762 mm OD 4 Thin -walled Tube, pushed I I IIII 73.0 mm 0, 762 mm OD 4 (25) Silty SAND (SM) I N 5 Bulk Bag Sample (from cuttings) -20 10 E 6 Hand Auger Sample 457/ Clayey SAND (SC) D 7 CME Core Sample 5 726 8 Lexan Sample -22 12 mm 9 Pitcher Sample Silty, Clayey SAND (SC-SM) 10 vbnacore Sample -24 14 6 11 No Sample Recovered Elastic SILT (MH) Sampler Driving Resistance -26 16 F Number of blows with 140 lb. hammer, falling 30-4n. to drive sampler 1-ft. after seating 7 SILT (ML) 1 N sampler 6-in.; for example, E Btows/ft Description -28 18 / `sm 25 25 blows drove sampler 305 mm 8 / 610 Silty CLAY (CL-ML) G R after initial 152 mm of seating j mm A 86/280 After driving sampler the initial -30 20 152 mm of seating, 36 blows I drove sampler through the Fat CLAY (CH) N second 152 mm interval, and 50 9 (25) E blows drove the sampler 128 mm -32 42 D into the third interval Lean CLAY (CL) 50/152 50 blows drove sampler 152 mm after Initial 152 mm of seating 7621 -34 24 10 762 ReV76 50 blows drove sampler 76 mm mm during initial 152 mm seating CONGLOMERATE interval Blow counts for California Liner Sampler -36 26 508/ shown in ( ) 11 • 610 mm SANDSTONE Length of sample symbol appiox- imates recovery length -38 28 Classification of Soils per ASTM D2487 or SILTSTONE D2488 40 30-M R lof m tterrvanl bold font at O the top erpreted inrmation MUDSTONE C Strength Legend 42 32 K Q a Unconfined Compression CLAYSTONE u = Unconsolidated Undrained Triaxial t = Torvane p = Pocket Penetrometer m = Miniature Vane SHALE Water Level Symbols 46 36 V. Initial or perched water level J X Final ground water level r GRANITE % Seepages encountered 48 38 r Rock Quality Designation (RQD) is the O� sum of recovered core pieces greater than a Paving and/or Base Materials 1D2 mm divided by the length of the cored interval. KEY TO TERMS & SYMBOLS USED ON LOGS ;�t� 0:s3PM;°"°" PPage 5U11of 1059 B-3 of 97 November 1999 Project No. 99-42-0411 E 0 E Iz aAwCt w w❑ p m a� � N Z ii w o m w Z3 ao �d0� An m LOCATION: Prcp .-d L:!! St4L'c- SURFACE EL: 37 m +/- 0.2 (rel, assumed datum) MATERIAL DESCRIPTION .E w Y 3F- Z� = 3 ,E p Y �= Z0 = 3 w Z a� 3z v c9 w AZ—n W a`o (L aR v -J U (/~(/�� QZ 0- o 1 o z� zz Topsoil/Artificial Fill (At) -_...._....... • ..._ .......- Lean CLAY with gravel (CL): hard, black, dry, with .................. ......•• ....._....••.•... --•..•.•.. ......... 1 (19) roots ......... .......... ... .................. ---1I--- _ ...... ...... ---------- ---------- .P..215 36 1 B ....... ...._... ... ....... .......... .......... ......... 2 ... (27) - with shale gravel layer at 1.6 meters ...--•-•..............................•.......-_............ "184 .................................. i4.B' -Z4" .......... .................... .......... .......... ......... PP21 ........... 35 2 Alluvium (Qal) Fat CLAY with gravel (CH): very stiff, black, moist . .......... ......... ................... .......... ................... 34 3 3 ::< . :: ,::. (27) - •fie: �.. _•,2-�. . `Y.. .. ... _..o`... .._._ rr i�[ i Fat CLAY r�u�• e. --tiff, a�.i, �. .. .. :..a 1 ). very ..tiff,da....rov , —ro-i-I -33 a 14.5 BGS = el. 107.5' ..••................ ......... ................... ......._ .................... ................... ......... 4 (8) .................... 13:1 ....................................... •14:7• ___.._... ••-36 • •......... ----••-.....A9••- ---------- ................... --•----- --- 28•• --•--.-- Pa24 V.21. Sandy Lean CLAY (CL): soft to firm, dark brown, wet, with subrounded and subangular gravel to .32 g approximately 3 mm diameter ............................. ........ 31 s NR 13 - with intellayered loose Gayey SILT (CL-ML) at 6 _........... ........... ..................• ...... -•--...... ........................ ......... ----.......... ..... ....... ... ..... _............... .......... .......... .......... meters........... 5 »> (5) 157''13:t 33_ ..8t....................... TV.21. 30 7 6 (a) 11r:4.. t3a... _ ••.................: -----.... - with light gray mottling and black o g g rganic pockets at......-•- .._.-•............. I-----••-- ••............................ 29 s 7.6 meters ....................................... ....................................... ..... •... ....... .....: --•- ....... ---••••- ........... 28 9 7 (6)427 ........... ....................................... .......... .......... ....... -... ........ •......... ...... . ----•- -• ........... .......... ; i ; - with interlayered SILT with sand (ML) at 9 to 10.5•' .....----• ............. --••...... .......... ......... ......... .................................... .... _.... . ----.- .......... meters .......... .......... --....... .......... .......... .......... Z7 10 ....................................••. .......... .......... 8 5 .......... ............ .......... . ..3T- .. ...... ••------- . .......... .......... .......... ....... .....ry.1.b ----_..... ........... 26 11 .......... ........ .............................................. ................................... .................................. Lean CLAY (CL): stiff, olive brown, wet, with organic .................. ....._............ --„ ..............I.....---_....-__._....-__....• ....... ...... ..... -.. . ........................... .......... ..... ..... -.- .... ..... ......... 25 12 9 >:; (18) pockets COMPLETION DEPTH: 12.3 m DEPTH TO WATER: 4.4 m BACKFILLED WITH: Cuttings DRILLING DATE: October 25, 1999 DRILLING METHOD: 203 mm diameter Hollow Stem Auger DRILLED BY: S/G Testing, Inc. LOGGED BY: CLLovato CHECKED BY: GSDenlinger 1M by and daft piaaread an a u pi6mbon er uhni eawiaone vmn"" at the time e16-Ov at tl- dnkd bead. SlMaha eendtbm mry d11et at od-I k aWm and MAIN t1r paneaps a tine. LOG OF DRILL HOLE NO. DH-1 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant DH LOG (9"26411.GPJ/DKG1) 11I4M (9:22:511 AM) i of November 1999 GR� Project No. 99-42-0411 Z E 0 S a a � p W g JO Lum �� �N Z W a (n N W J o. H w JO �v 3 �� m LOCATION: Station 2+90, Right 5 meters SURFACE EL: 39 m +/- 0.2 (rel. assumed datum) MATERIAL DESCRIPTION w z x 3� = �� W� 3 z O �= 20 �W � 'Wz a� z �O U Z w W(n a�' a8 *� p �H og �— J 'R UX yuw p aZ ti A v r� W z4 a: aof Z ♦- z • Artificial Fill (Af) .. ...........................................-- ------... .......... r • 76 mm Asphalt Concret Pavement (AC): - .......--• .......................... .•. .......... ..... (14) _19 ....1.5.3....26 - - ................................. ---------• -•-•------ ---------- ----------- .Pa.e6 406 mm A ate Base: 99re9 Alluvium (Qal) Fat CLAY with gravel (CH): stiff, black, moist, with angular red chart to 25 mm 1 A 2 ;. (15) .................... .. • .. . ... ................... —2-7... .................... .......... ..---.... .......... ..... . PP, !!@ - with shale clast at 1.5 meters _........ .... ........... ---------- s7 2 3 (19) Fat CLAY with gravel (CH): stiff, dark brown and .................... .......... .................... ......... ........ ............ .......... .._....... .......... mottled light gray, moist 4 > (12) - medium stiff at 2.7 meters -192. -.15.3- ..25.. _....__.......................Pp..57. ••--.........------. --........ 36 3 5 10 - with subrounded shale lasts to 6 mm at 3 meters .... .......... ......... .............................. - ......... ...................... ........................... ••-••----- --•------- .. •- In --..... .......— 35 4 ................... ..............•... -- .......... _......... .......... ................. .................. ......... •.. ......... ...._....... --•---.................................. _........................... 34 5- ---••..... .............. ..... .... ......... ........ ............ ........................................ .......... .......... ----------- .......... .......- ................... .................. .....................•........._....... .•---•......._........._................ 33 S ................................. ................................... .......... .............................. .......... ......... .......... .......... .......... .......... .......... .................... ........... 32 7 .............................. ....................... .... •-- ...... ........................................ .......... ............. ... ......•....................._ ........................................ ........................................ 31 8 .......... ................... ................... .......... ........................................ ........................................ .................... .......... .................... ........ .............. .................... .......... •......... .......... ........... ........... 30 9 ............................. ................... ......... .......... ... I ...... ...... .......... ..._..... ........... ........... ................... .............................. ......... .................... .......... .......... .......... ..._..... ......._. 29 10 .............................. .............................. .......... .........• .......... ..................... .................... .. ........ ........................................ .... ..... .......... .......... 28 11 .......... .......... .......... .......... .......... .......... .......... ...... •............. ......................... .......... ............... .......... ..................... .......... .......... .... .......... 27 12 ................... •........ .......... .......... .......... .......... COMPLETION DEPTH: 3.4 m DEPTH TO WATER: Not encountered BACKFILLED WITH: Cuttings DRILLING DATE: October 25, 1999 DRILLING METHOD: 203 mm diameter Hollow Stem Auger DRILLED BY. SIG Testing, Inc. LOGGED BY: CLLovato CHECKED BY: GSDenlinger 1M b9 and data grasented an a t' ip 15,atior of actual eonaiom ancoaaend at the tine of drug at the dried to i . Subsurface rnadbon may Mar at other location and with the passage of Ow. LOG OF DRILL HOLE NO. DH-2 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant Pagel Eif *089 B-5 of 97 DH LOG (99420411.GPADK02) 11/4M (8:54:56 AM) November 1999 Project No. 99-42-0411 GRID E p E r of P J O w wm to O Z J N y w J CL 0 Z w D CLO o N J m LOCATION: Station 5+00 SURFACE EL: 40 m +1- 0.2 (rel. assumed datum) MATERIAL DESCRIPTION E w 3 z� �W 3 y �� z� 'W 3 '� w WW 3z� V t7 y W to IL 7Rit O �r 0� r C Z 0. ti p a w Zz K Artificial Fill (Af) ..---•.................................. .......... ......... Sandy Lean CLAY with gravel (CL): very stiff, brown, •"""................ ......... ....................................... 39 1 1 (26) dry - moist below 0.6 meters .......-.. 19.6.._ifi fi. ..................... _.18... .......... ............................ ........__ _...___._ PP�1�5 2 z (13) medium stiff at 1.2 meters ..... .... 15?....13 •.................. fi...15 ............ .•••--•....................._........_ ........ ........... EP 2t5 38 2 3 '`'"` (37) -..... - -.... Ina .................................... 40 ....4 - PP Alluvium (Qal) Fat CLAY with gravel (CH): very stiff to hard, black, _.. ---- ..... moist ... ..... _........ 4 (21) - grades to dark brown 37 3 5 � � 12 - stiff with light gray mottling below 2.4 meters - 36 4 .................................................. .......... ... _.._. .......... ........... .......... ..... :.... .......... ......... .......... 35 5 .... -- -_ .......... ..... .... ...... 34 8 ... .N~ 33 7 ....._.. ........... ...»..... .......... .......... .......... ......... 32 8 .... ..... .......... ......... .......... ..__.... ._..... ............. 31 9 ................_......_...........• ............................. ............................... .......... .................. ........... ......... .-....... .. .......... ..... ..... .......... ........... ........... 30 10 ....---. ........................................ _ __..._.. .....•............................... .... .......... .......... _... ..... 29 11 .......... .................... .......... ......... ..._.... .............................. .......... ........ _ .......... .................. .................... .............................. ......... .......... _. ............................. .......... .......... .......... ......... 28 12 .................... .................... ...•..... .................... ..._.......................... .................... ......... ......... COMPLETION DEPTH: 3.4 m DEPTH TO WATER: Not encountered BACKFILLED WITH: Cuttings DRILLING DATE: October 25, 1999 DRILLING METHOD: 203 mm diameter Hollow Stem Auger DRILLED BY: SIG Testing, Inc. LOGGED BY: CLLovato CHECKED BY: GSDenlinger TM"and data prasanlad a a Orp"Catien of ataal condtiorn anetaa wod at Ow hna of drip at do * On W=bw Sibaafaa sardtim+a may dtfa M other WcoOmm"Mfh tM pampa of tine. LOG OF DRILL HOLE NO. DH-3 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant PagRl�hTFofAtA9 B-6_of 97 OH LOG (G9420411.GPJ/M"3) 1114199 (8:55:07 AM) November 1999 Project No. 99-42-0411 V N Z r b g1Yn x Il.l g em < < c In to) �U�S�e 1 1 (3S) 1N3,ly=03 aoU8UMzw ONYS N o 3nldn-a sue» �Ag E c d z�as55 Ea as CO N ---•................................... . ...... ......._.... - .... �~} �� EW 0212vil6px8 U It i �Fv/LZ<a -.. •-•-------- - 0 a .......... .....-...................... .............. --.....----_.... ................ _....__...... ............... A tr f E E e0 n� ao zr W �aW rnf—y NAY top m » o , �ww _..s-- _______________ ____..__._.__....___...:_ _ __._..._____....---__---.---._. --.._.-_.---- ------.-._._ ......_........ __..__..__.__.. ______...._.___ o x N d Y .1 = Q U C a U N Uh U a� �- < UQt- N ............................. WLLI ............... ...._......... ....... ......... ..._._. ..._.........._._... __._........_ ......_........ --- ............................ OUY a c I N gg a 0. E� o Ito oI : I z $ C O a ___.Q __ a f- .-----_------- ------ -------- ----____.--_.- _.__._..._._.......___._....._ _...._..__..... ..._.........__ ......._._..... __......._..__. _ ._____....__. i c-» „ c c A LLU O OZ R1 '»§aFf U „ u n n u Ur a M N O Q m C) mo so o� ac » Y < lL Za' io o� LL E E g Q� NEE LLL oMo g$B J U Ci n U U N= N m m a 11 a > > > m U U U J U U U E�a- �rn 1 } c } ci�so -if Q IM N m } } U U } CO �� .3 ; t U U U U } d d w �2 m m J J J J J v v COr v v r J J J ll fA fn (n 110 In N oa m: 'e�13300 0 ur tr E �: co : m: co : N; In E chi r� ; v; c+r co in! n i m: ; r-. CO a 1ID _ �, : fV : t!1 tD U. N E Z o N Z Cr U O 7, 1 71 J 0; O: Di O; ❑i O: O: Qi O: Oi U » f ii a GRa LO rn 0 0 O CO C Cu d. C N ... E J N in yam/ �^^'' i W r•+ w n 3 _ (n j Q' O 3:3 J L C CO t� C � = o ca � J C C CD Ca J LO 0 LO ca I- PLATE B-1 a November 1999 Project No. 9942-0411 woCO J in :9 o mocill u�x n n (3S) 1N31VAlno3 o� n II n a000 000_W aNYS - C F N o N 3nim-a so„82- �ocp E c O VI H U �A OOJ O OOC CO So H <.H ui H a.!?a KOo } U iF-Ul i�x<U u a u p n u n 0 =n -........................ ..... .............. ---------------- --•---- ------- W U 4 s E c n n LU YA Y f- -C 7 Ca m 0- w w S2_• _... -_-•••....... .............................. ......... ... O ....• • ------- '` 8 n V v, 11 Ix �F- �m '��j iiY f31� aU Vi U CO Ucc a� <F' v Ir Ui =F off$ I Ira Z a z- P N v c > 1 N.... ui ............................ .------------- -............. ................ .................. o �c c D- p OZE U u E I a I Z i o. O s UCO8� LL ui 9 g- o c Off E J U J U E c E L C o�p gc4� U � O M N t0 N 1� 2= CD CV In N > OD > N OI n p o $ a w i i S = d _ '_' $_OU aQ a U U 20 o > > > > > > t�7�0 UIL Q CO p E m 0 �+ Lam o, CMino, 1c to �+ DY U L r O J J Y A N U U U U O U O U C N C O U N t,+ul J LL U-li I I li I IL I IL (Q fn LT . E : w�: rrJ M 2 L c u W d' E : O: �: (G i0 : <: (O : N: N M; CO Q: < Ni �-.. (A iv: 1v Z = :O ir- N iN iC _� CCn E- c ccm C F G C C N ypV YCO LU 0 n IN a. VZ p is is _ N is N Ni is Ni _ Mi is f�lr Mi.11 _ o c, g II J Di 0: i 0: i 0: i 0: 0: ❑: Ol U O�LL�D.' GRO rn o 0 4-00 co 0 LO a� cr3 a- (Q a_ N E J tII (D L Y CD CD n 3 fO CO j O 0 2 L C CQ U) C C: O a (Q �_ to �II m Ca PLATE B-1 b November 1999 Project No. 99-42-0411 (3S) 1N31b7 603 �uu ]xxx <pU8u�zw ONVS = 3nivA-a 0 � N EaO� V1 .......... H— .............. ......... -... .............. .................................. ..._....._...... - o.a b a � v pEE �F:. fA 2tU 11 11 11 11 II x x mIr.x<a -........ n 0: Z O ............ •............... ..............•. ............... ............. _ ............... ............... '---•-........ S Y E E E o u n C,� U)I.- N !n(7� o W Zf ................._.....---...--....----- -__.......................... ..•--.-..-..__. ..--------•---- --------------- --------.... ................S� It X W W-.0a._. E- L7Y pptton lz a U- Uy -m Qv .._._ .... ....................._... .._._._.. �WW ------- -' ............... .........----- _...._..._...... _ .............. ................ ..... O CO U � @ `w e c o a��s �N o ...------._... .............•- ----••--•------ ---..----•---- ----------•-• =-a t L� is g < LU---._•-•- 0 �R�1,2M „ n "E U CgR an:l a Z o o � O J U 9 Q y P • (� = 8 I E E aaL a o C o N L) be_to_ C. 11 11 O �•- v�<c LLJ U U E. kkc � tS1�8 UC N p-E of to a t_ t 3 •3 J"Z U 0 ( 1 pc x ul r p =o Y o £ ; : �, - J W , N 3pe.�Eg 0 n. IM Q�ccTnaa'� z a -+ Q (OZ a O '• a>>oaR=� t^ xx Jn n• UU1 cD Si M; S; N u x a U c - U7�k-U. i�a GRO LOrn .: o0 rn --. Opp r` 0 LO U7 ^M _ cn Cl- N Cn E _J Cu M CD W �D r w UJ cn 3 4) H (n Ca .C3 O O m Mn g� J LL. C O cQ C� C G O Ca S_ rn M N Cu C 0) Cu J PLATE B-1 c November 1999 Project No. 99-42-0411 .......... .......... . ... ............. . . .... . ............... -------------- /ZLor OL . . ..... ...... . ............ e .......... ......................... 0-4 .................... I ........ ...... . .................... ML: or OL io- 3 . 0 4 . 0 LEGEND (location) (depth,m) 0 DH-1 2.7 0 DH-1 4.3 ORD ............ ........... ........ .................... ............ Z ........................... 7L ................................ --------------------- o OM r .......... . ..... ............ ................ ................ .. ........................ ............... ........... ........................... ... --------- I - - ----------------- LIQUID LIMIT (I-L) CLASSIFICATION Fat CLAY with gravel (CH) Sandy Lean CLAY (CL) Lei MH or OH ATTERSERG LMTS TEST RESULTS LIQUID PLASTIC PLASTICITY LIMIT(LL) Llmrr(PL) INDEX (PI) 62 28 34 49 21 28 PLASTICITY CHART Laguna Lift Station San Luis Obispo Wastewater Treatment Plant PLASTMMY CKART (2U20411.GPJ101401) 1 1rJ199 (818:19 PM) b _ g November 1999 Project No. 9942-0411 200 180 160 140 m 120 y w 100 y Q w = 80 60 40 :..............:.---.-...------..................... ........................... ---- ---- ; 20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 800 NORMAL STRESS. kPa . EFFECTIVE COHESION, kPa 30 EFFECTIVE ANGLE OF INTERNAL FRICTION, deg 13 LOCATION DH-1 DEPTH, m 4.3 MOISTURE CONTENT, % 30 UNIT DRY WEIGHT, kN/m' 14.7 MATERIAL DESCRIPTION Sandy Lean CLAY (CL) SAMPLE CONDITION Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant DIRECTSHEAR (99170/11.OPLDK01) Hrw9(l:20:51 PM) s November 1999 Project No, 99-42-0411 200 180 160 140 40 -------. .----. ..:......... ......... -------....... _.... ............ ............. _......... ........ ......... _ ............. _ ......... 20.... .-......... -----.. ___. ......... ......... ......_.... ._........ _.. _ ._._..._ ........ .._..... .............. .................. _....... __........ 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 NORMAL STRESS, IPa EFFECTIVE COHESION, kPa 21 EFFECTIVE ANGLE OF INTERNAL FRICTION, deg 14 LOCATION DH-1 DEPTH, m 6.7 MOISTURE CONTENT. % 33 UNIT DRY WEIGHT, kN1m3 13.7 MATERIAL DESCRIPTION Sandy Lean CLAY (CL) SAMPLE CONDITION Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant DIRECT SHEAR (99420411.GIRROM1) I Irmo (A120:53 PM) PaPhT90M49 November 1999 Project No. 99-42-0411 200 180 160 140 60 GR_O 40 20 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 NORMAL STRESS, kPa EFFECTIVE COHESION, kPa EFFECTIVE ANGLE OF INTERNAL FRICTION, deg LOCATION DEPTH, m MOISTURE CONTENT, % UNIT DRY WEIGHT, kN/m3 MATERIAL DESCRIPTION SAMPLE CONDITION 30 14 DH-2 2.4 11 15.3 Fat CLAY with gravel (CH) Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant DIRECT SHEAR (99420411.GPJMK02) I IrY9G (8:20:50 PM) Pao%-61T-0J3Ag9 November 1999 Project No. 99-42-0411 "E 21 20 17 Is ....... ..... . ...... ...... AStM 61551 .............. ........ ....... ... 0 5 10 Is 20 25 MOISTURE CONTENT, % MAXIMUM UNIT OPTIMUM WATER LEGEND CLASSIFICATION DRY WEIGHT. kN/rn' CONTENT, % oomtion) (depth,R)- 0 OH-1 0.6 Lean CLAY with gravel (CL) 17.2 15 COMPACTION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant PLATE B-4 COMPAvnON (METRIC) (M2041 I.GPJIDPI-01) Page 512 of 1059 1114W(811:45EMI ORD November 1999 Project No. 99-42-0411 z Q f- rn 0 2 .. 3.................... i.......... .y.......i...... ._.. •--- i ... ..s..._................b.-------.j._..... i.....v._.• ....... j--i............_.......;...........i.......o..........}......�..... 4 6 . 7...................f........... } ........ ...._.}-...i-...{ --- i...p._................. 4........... {-------- /.....-}..._;...{..•r..i........................ i... ....... ....... 1 D ------ 11.................... ........... }....... j...... ;.... j.... }... 1..;--•}------ ............. ;----------- ;........ j..... }.._. {....}.. }..{_.;........... 1---------- .... .. _..;.....}... j... j...j.. 12 10 /o0 1000 VERTICAL EFFECTIVE PRESSURE, kPa LOCATION DH-2 DEPTH, m 1.2 INITIAL MOISTURE CONTENT, % 27 UNIT DRY wElrur,. �r;kIM3 IJ MATERIAL DESCRIPTION Fat CLAY with gravel (CH) SAMPLE CONDITION Driven Ring CONSOLIDATION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant I�1� gg 55 CONMUDAMN(00�20411.GPJMK02) PATE 513 of 1059 .- 11M➢(0:17:19PM) ._..__......_....--------------------------- -- .---------._..--------------...-----__.------_...------------8=15b#-97 November 1999 Project No. 99-42-0411 i r-4 0 1 --------------- - ..._.. _ - - _ ...._..... _ ...._. .. - - -......._ . 2 ... ........... ....... 3 --------- ---------- y... _...... }----- -+...__�_...h...i...i..+............................. ..;_.....I...---i.. ...i... ...._........j...i.. 4 ............... ...... ... _ ___ __;._...-........ ... ..;..{................... ..... 5 _.......... _.........._ ... _ ------._.......... _ _.... _ .. - - - _._..... - - 6 _.._.._ ...... 7 .... ..... ......t.__...... �_._._1......i-...{....i._i f i........ _.. _ i_...._.i.....y_...�...._d..i..H--_.-------__ + .... i....... .. t_....i. �_..+...y.. i� $ -.......- ...... ...... . ..._.....____ ....._ .. _4...... ........ ............ l.._...._..- .........._.... ..�._... __ : 9 ..._...__.._ _.__. ...- - - - __......... ..... .. __ _ ......_...... ..... - _ 10 . __.. i-..... -I ........ _.... -..i •...... i-...4._ .. t-. ........... ........... ._........ j....... I ...j....4._.j...l t.S......... ........� ..........{........ j...... } i --- 4-4-4-4----.._--•--..-_..-i....._.....j.......n.._..{----.j_..t.._i.. .. 121 .10 ino 1000 VERTICAL EFFECTIVE PRESSURE, kPa LOCATION DH-2 DEPTH, m 2.4 INITIAL MOISTURE CONTENT, % 25 UNIT DRY WEIGHT, kN/m' MATERIAL DESCRIPTION Fat CLAY with gravel (CH) SAMPLE CONDITION Driven Ring CONSOLIDATION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant CONSOUCAMON (YM26111.GP!/ON-02) PLATE B-5b Page 514 of 1059 --B-1-6-of-97 ealth Renee ssociateS LABORATORY REPORT Report Number : 100338 CHRIS LAVATO Purchase Order : FUGRO WEST INC. Job No. 99-42-0411 1012 PACIFIC ST. SOITE A SAN LUIS OBISPO, CA 94301 Sample Description : 1- Bulk Soil Project . California Test Methods : 532,643 Auto Submitter Resistivity pH Chloride Sulfate No. Sample Number ohms/cm Units ppm ppm -_204524 DH-1-2 @ 6' 3,449 7.28 - Date Received : 29-OCT-99 Date Completed 05-NOV-99 Date Sent : 05-NOV-99 Page f 1 of 1 `Milliliters Water Added 50 100 150 200 250 300 350 400 -------- -------------- Resistivity Ohm-cn-------------------------------- Sample No. DR-1-2 @ 6' 3630 3812 3630 3521 3630 3449 3812 3739 _Remarks : Sample(s) and sampling data as provided : Analyst(s) : ED Ref by : C. Wockner California FLAP No.: 1406 Reviewed by: �.0 5 1 � u --AIHA Accreditation No.: 172 Tbomas Shultz NVLAP Accreditation No.: 101384 =AIHA ELLAP Accreditation No.: 10985 Technical Approval:CIO.-,CZ:)tJL,_::) —InLr LACSD Lab No.: 10125 Laboratory Dir, or, Jamie Steedman-Lyde 10771 Noel St., Los Alamitos, CA 90720 714/220-3922 FAX 714/220-2081 e-mail hsaCe earthlink.net Attachment 'Iris report pertains only to the samples investigated and does not necessarily apply to other apparently identical or similar materials. l 0 5 9 for the exclusive use of the client to whom it is addressed. My reproduction of this report or use of this Laboratory's name for a ve i orpy �b j.c�t purposes without written authorization is prohibited. C I / yof 97 m N W H rn r-- LO cr) C O O 00 �o m LO aD c� I , I � I I I I , 1 I I 1 III it I � ' N N C L r� E vn �ryo I�7g Im7� o b Z ma 1 -azv). , ia"ii a N w z `° a a Oa _ a� U .S Oar � O (9 .� Z>16J 7 C O CO In m 3� `o 00 m m~ VA � m r L � CL a a yuZI U aajl u Q Mr-- LOm o - O O ti m LO N (B Standard Penetration Test (SPT) split spoon sampler having a 2-inch (50 mm) O.D., 1 3/8-inch (35 mm) sI.D. and without liners. Sampler is driven in three 6-inch (305 mm) increments by dropping a 140-lb (63 kg) weight 30 inches (760 mm). The reported blow count is the sum of the blows for the last two increments. CAM California split spoon sampler having a 3-inch (76 mm) O.D., 2 3/8-inch (60 mm) I.D. with liners. CAL Sampler is driven in three 6-inch (305 mm) increments by dropping a 140-lb (63 kg) weight 30 inches (760 mm). Thick-walled modified California split spoon sampler driven 12 inches (305 mm) using the rig's kelley Is I Thin -walled Shelby Tube sampler that is pushed into the ground using the rig's hydraulics. FSand Cone Sampler MM JHANq Hand driven modified California sampler with liners. LIW XBulk sample obtained from drill auger flights, backhoe cuttings or hand excavation. NR No recovery Consistency of Cohesive Soil: Cal N-Value SPT N-Value Undrained Shear Strength (Su) psf k a Consistency 0-2 0-1 < 250 < 12 very soft 3-6 2-4 250-500 13-25 soft 7-12 5-8 500 - 1,000 26 - 50 firm 13 - 22 9 - 15 1.000 - 2.000 51 - 100 stiff 23 - 45 16 - 30 2,000 - 4,000 101 - 200 very stiff > 45 > 30 > 4,000 > 200 hard Relative Densitv of Granular Soil: Cal N-Value SPT N-Value Consistency 0-6 0-4 very loose 7 -15 5 - 10 loose 16 - 45 11 -30 medium dense 46 - 75 31 -50 dense > 75 > 50 very dense S,,,� PP n Undrained strength (t = torvane, uu=uu triaxial, pp = pocket penetrometer, h = hand vane) Initial depth to groundwater Groundwater level after drilling Notes: Soil classification and descriptions are performed in general accordance with ASTM D-2487 and ASTM D-2488 based on the Unified Soil Classification System. The logs represent the interpretation of field classifications and testing, interpolation between sample intervals, results of laboratory tests, and the conditions observed at the time of exploration. The transitions between soil types and strata are approximate and can be gradual. Soil and rock materials vary in type and other geotechnical properties between points of observation and exploration. Groundwater and soil moisture conditions vary seasonally and for other reasons. Explorations and services have not been requested nor performed to assess the presence of absence of hazardous or toxic materials. San Luis Obispo Water Reuse Project San Luis Obispo, California LEGEND FOR TRENCH LOGS Project No. 01-52-0721 _ Figure A-1 Page 518 of 1059 B-20 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 12, 2002 Driller: S/G Testing Completion Depth: 3.4m (11.0') Ground Elevation: 36.5m (119.7) Groundwater: Initial depth: After drilling: Logged by: G. Fiegel Comments: Groundwater was not encountered Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cuttings Depth m a' a c ^ o a) '� c M E -• c cY ^ �v ` m E ° 3 3 a E `-' a DESCRIPTION AND CLASSIFICATION a = c `� Other O Y O O OL O Tests OCOU Af Artificial Fill: - sPT 4 1 3" (75 mm) Asphalt Concrete over 15" (375 mm) 29 Qal Base Material sand and ravel Alluvium: 1 Fat CLAY (CH): soft, dark green, moist, orange 5 CAL 12 2 staining, with trace amounts of gravel (18 6) 32 - medium stiff, dark gray, brown and gray mottles, 2 sPT 7 3 blocky structure 29.4 - orange staining 3 1 j ` 18 4 -stiff 119 (18.8) 30.2 Pp=2.5 ksf Total Depth = 11.0 feet (3.4 meters) 4 - 1 5 6 2 7 2 8 9 3 San Luis Obispo Water Reuse Project BORING NO. B-305 San Luis Obispo, Califomia SLO WWTP Property Project No. 01-52-0721 Figure A-16 Sta. 0+860, CL of Pipe Page 519 of 1059 B-21 of 97 Drilling Method: 6 in (150 mm) Hand Auger Date: March 19. 2002 Driller: Fugro Completion Depth: 4.9m (16.0') Ground Elevation: 36.6m (120.0') Groundwater: Initial depth: 4.6m (15.0') After drilling: 4.4m (14.5') Logged by: G. Fiegel Comments: Hammer Type: 5 lb Hand Hammer Backfill Material: Cuttings Depth N a� .. " c E .. _0 ° _ C �� _ cn cn 0 3 E o DESCRIPTION AND CLASSIFICATION a N a Other Tests �, `` Y 2! 0 2 m� U) o o ��M0 o � Qal Alluvium: Fat CLAY (CH): stiff, dark brown, moist, occasional roots, orange staining 1 HAND 40 1 - dark gray I 5 - black, occasional gravels and sands, subrounded, H ND 80+ 2 gray silt partings 2 - gray, orange staining, manganese specs 3 1 I - yellow brown, orange staining, manganese specs HAND 32 3 - medium stiff, occasional gravel 4 - black, occasional sand and gravel particles, orange stains 1 - soft, brown, increasing gravel and sand 5 HND A 1 d - medium brown, wet, with sand No Recovery ` Total Depth = 16.0 feet (4.9 meters) I 6 2 7 2 N r g o c� I 0 w V7 U 9 3 San Reuse ®mom BORING NO. B-306 SanuisOispo Luis Ob spoeWatfCal fo n aroject m SLO WWTP Property Project No. 01-52-0721 oReclaimed Water Tank Figure A-17 J rage 520 of 1059 B-22 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 5, 2002 Driller: SIG Testing Completion Depth: 4.1m (13.5') Ground Elevation: 40.5m (132.8') Groundwater: Initial depth: After drilling: Logged by: G. Fiegel Comments: Groundwater was not encountered Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cuttings Depth c c a u, C. a M j o w a) D DESCRIPTION AND CLASSIFICATION c Y aC a� v Other N N: Y 3 3 o m U) o O m 0L O Tests 75 CD Af Artificial Fill: 10" (250 mm) Asphalt Concrete over 8" (200 mm) SPT 8 1 Base Material sand and ravel 19.3 Lean CLAY CL : medium stiff, dark brown moist 1 j K A Oal Alluvium: Compaction 5 c1 17 2 Fat CLAY (CH): stiff, dark brown, most, some 119 18.5 orange staining (18.6) sPT 2 8 3 - dark gray 3 1 4 CAL 19 4 - stiff, occasional decaying roots (122 ) 22.6 Total Depth = 13.5 feet (4.1 meters) 1 5 6 2 7 2 8 9 3 San Luis Obispo Water Reuse Project ©� BORING NO. B-401 San Luis Obispo, California Prado Road, Sta. 0+525 Project No. 01-52-0721 CL of Pipe Figure A-18 Page 521 of 1059 B-23 of 97 Drilling Method: 8-V4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: SIG Testing Completion Depth:15.3m (50.3') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.5m (245) After drilling: 7.5m (24.5') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth a� a a o c _ _ cY �8 Cn E E in o� 3 3 a E o DESCRIPTION AND CLASSIFICATION a Ln a Other Y o 0 07 0 o Y a Tests �CO 'm Af Artificial Fill: 7" (175 mm) Asphalt Concrete over 4" (100 mm) Co=1, VOC=0.8, sPT 13 1 Base Material (sand and ravel 12.6 H,S=O, 1 Fat CLAY (CH): stiff, light to dark brown, moist, with _J LEL=O, PP>4.5 ksf few pieces of subrounded gravel to 3/4" (75 mm) diameter Grain Size 5 CA CA ]L 17 17 2 22 - with pieces of plastic 114 15 1 VOCo=0 5, (18.0) LEL=O, pp>4.5 ksf Qal Alluvium: Lean CLAY (CL): stiff, dark brown, moist 3--JC C0=1, VOC=0.5, sar 10 3 H,S=O, LEL=O, pp>4.5 ksf 4 Atterberg - 1 - with medium grained sand layer Limits, UU cA� 17 4 (18 6) 1119 8.2 C0=0, vo S- �2, 5 z- LEL=O, pp>4.5 ksf 6 2 C0=0, VOC=0.5, sar 15 5 - with 3" (75 mm) thick sand layers H,s=O, LEL=O, pp=1.0 ksf 7 Well graded GRAVEL with clay and sand (GW-GC): _ medium dense, light brown, moist 2 8 CAL 32 6 123 (19.3 ) 22 9 X co=o, Lean CLAY with sand (CL): stiff, orange brown, wet VOC=0.5, sPT 12 7 H,S=O. LEL=O, San Luis Obispo Water Reuse Project ®� BORING NO. B-402 San Luis Obispo, California Prado Road Project No. 01-52-0721 Sta. 0+760, CL of Pipe Figure A-19 rage o« or i uoy B-24 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.3m (50.3') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.5m (24.5') After drilling: 7.5m (24.5') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth _� a d �_ C O a)GY Irl _ E -- �o U O 3 3 DESCRIPTION AND CLASSIFICATION a `� a O O cn O Y O O U) _o O �v O L O Tests m m C7 � m 0 Lean CLAY with sand (CL): stiff, orange brown, wet Pp s (Continued) 1 3 CAL 41 8 138) (21.6 19.4 Poorly graded SAND with clay and gravel (SP-SC): medium dense, orange brown, wet 2 q CO=1, SPT : 20 9 VOC=0.8, H2S=0, LEL=O 3 Fat CLAY (CH): very stiff, moderate light gray brown, moist, with pieces of gravel to 3/4" (75 mm) diameter 4128 4 CAL 35 10 (20.2) 22.7 pp'4.5 ksf KJfm Franciscan Formation: 5 CLAYSTONE - "Fat CLAY (CH)": moderately hard V000.5, 5 sP , rock moderate) weathered, light gray brown H2s=o, Total Depth = 50.3 feet (15.3 meters) LEL=O 16 5 7 8 6 9 San Luis Obispo Water Reuse Project ©� BORING NO. B-402 San Luis Obispo, California Prado Road Project No. 01-52-0721 Figure A-19 Sta. 0+760, CL of Pipe Page 523 of 1059 B-25 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.7m (51.5') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.6m (25.0') After drilling: 7.6m (25.0') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth `� aU " c E C \ (n E U c i o- 3 3 a E o DESCRIPTION AND CLASSIFICATION a �.. `n � Other N Y O p O O O C u_C-5�� �co 3 Af Artificial Fill: 9" 225 mm Asphalt Concrete co=2, VOC=5.0, I Lean CLAY with sand (CL): stiff, dark brown, moist, SPT 9 1 9.9 H2s=01 1 with pieces of brick, concrete, and asphalt up to 3" (75 LEL--O,ipp=" mm) diameter I - 5 7 21 2 118 (18 6) 13.3 Direct Shew 2 I 3 1 I SPT 2 3 - piece of gravel stuck in sampler shoe I Qal Alluvium: 4 Fat CLAY (CH): very stiff, light brown, moist, with su�K A trace amounts of subrounded to rounded sand and 1. gravel uu, 0.2 voc=o.2. CAL 28 4 (20 6) 19.3 5 LEL=O, - W4.5 ksf 6 2 Co=1, I VOC=0.5, SPT 8 5 - orange brown, with few black specs H=s=o, LEL=O, pp=2.0 ksf I 7--Sandy lean CLAY (CL): stiff, light brown, moist 2 i Z Atterberg 8-- CAL 11 6 - wet (19.5) 28.1 Limits, uU Pp=2.0 ksf I Fat CLAY with sand (CH): stiff, light brown, wet 9- 3 CO=2, VOC=0.5, SPT 12 7 H,S=o, LEL=O, San Luis Obispo Water Reuse Project �© BORING NO, B-403 San Luis Obispo, Califomia Prado Road Project No. 01-52-0721 Sta, 0+820, CL of Pipe Figure A-20 rage o<<+ or i uoy B-26 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.7m (51.5') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.6m (25.0') After drilling: 7.6m (25.0') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth E o a a E jo w EY a�a `. � in 3 3 o DESCRIPTION AND CLASSIFICATION a —D a)Other Tests u- Y o o m n cEo o o- ~ rn o c O m Cg � U 0 Fat CLAY with sand (CH): stiff, light brown, wet pp=2.0 kSi (Continued) 3 CAL 12 8 - without sand 120 31.1 uu, pp=1.0 1 (18 9) ksf 2 4 Co=O, v sPT 8 9 - medium stiff H2S, =O,S= LEL=O, pp=1.0 ksf 3 4 4 cu 14 10 -stiff 131 (20 5) 20.5 PP=2.0 ksf -5C Co=1, voC=0.5, sPr 35 11 - very stiff, with frequent charcoal inclusions H2S=O. LEL=O, Total Depth = 51.5 feet (15.7 meters) 6 pP>4.5 ksf 5 7 8 6 9 San Luis Obispo Water Reuse Project �© _ BORING NO. B-403 San Luis Obispo, California Prado Road Project No. 01-52-0721 Sta. 0+820, CL of Pipe Figure A-20 Page 525 of 1059 B-27 of 97 Brown and Caldwell Project No. 01-52-0721 70 60 0 50 k 40 c 30 a 20 10 Atterberg Limits V��e . .e 01 2 106-2 f,,• CH or a 304-3; 704-2 O 0 2-2 303- 5 MH or OH ICL oe-20120103-4 03 402-4 602-2 8X or OL CL 10 20 30 40 50 60 70 80 90 100 Liquid Limit - Sample Depth (ft) Description and Classification Liquid Limit Plastic Limit Plasticity Index 101-2 4.5 Fat CLAY (CH) 70 21 49 104-2 4.5 Lean CLAY (CL) 49 22 27 106-2 4.0 Fat CLAY (CH) 74 25 49 201-3 6.5 Lean CLAY (CL) 42 21 21 203-4 14.5 Lean CLAY (CL) 37 19 18 204-3 9.0 Lean CLAY with sand (CL) 42 20 22 303-5 19.0 Fat CLAY (CH) 56 25 31 304-3 9.0 Fat CLAY (CH) 70 27 43 4024 15.0 Lean CLAY (CL) 39 20 19 403-6 25.0 Sandy Lean CLAY (CL) 32 18 14 502-2 4.0 Sandy Lean CLAY (CL) 31 18 13 702-2 4.0 Lean CLAY (CL) 44 20 24 704-2 1 4.0 1 Fat CLAY with sand (CH) 54 19 35 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D4318 ATTERBERG LIMITS TEST RESULTS Water Reuse Project San Luis Obispo, California P LApa5e` -A of 1059 B--2Sofi 97- Brown and Caldwell Project No. 01-52-0721 100 r*J to 60 o, c C 40 c as as a 20 Mechanical Sieve Analysis Results 10 1 Grain Size - mm roxi roxilil GRAVEL SAND SILT or CLAY coarse Tine coarse medium fine Symbol Sample Depth Description and Classification C, C (ft) 402-6 25.0 Well Graded GRAVEL with 2.8 124 Clay and Sand (GW-GC) Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D422 MECHANICAL SIEVE ANALYSIS RESULTS Water Reuse Project San Luis Obispo, California PLATE B-2d Page 527 of 1059 B-29 of 97 Brown and Caldwell Project No. 01-52-0721 M Compaction Test Results 116 114 fffl-1 `C+Il 10 12 14 16 18 20 Water Content - % Symbol Sample Depth Description and Maximum Dry Optimum Water (ft) Classification Unit Weight Content ( co (%) ♦ 401A 3 to 6 Fat CLAY (CH) 113.5 15.0 Projcct: City, of San Luis Obispo Water Reuse Project Test Method: ASTM D 1557 COMPACTION TEST RESULTS Water Reuse Project San Luis Obispo, California 1 • • Brown and Caldwell Project No. 01-52-0721 10, Or 2 a 8 10 12 Consolidation Test Results Consolidation Stress - psf lop 10, 106 Symbol Sample Depth Description and Total Unit Weight Water Content (ft) Classification (pci (%) • 404-2 4.5 Fat CLAY (CH) 127.4 23.6 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D2435 CONSOLIDATION TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-4d Page 529 of 1059 B-31 of 97 Brown and Caldwell Project No. 01-52-0721 Direct Shear Test Results E"I 3 1 01 1 1 I 0 1 2 3 4 5 Normal Stress - ksf Symbols Sample Depth Description and Friction Angle, Cohesion, (ft) Classification (degrees) c (ksf) ♦ 403-2 5.0 Lean CLAY with sand 37 0.1 (CL) Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D3080 DIRECT SHEAR TEST RESULTS Water Reuse Project San Luis Obispo, California P L Page6�&of 1059 B-32 of 97 Brown and Caldwell Project No. 01-52-0721 L02 5 4 1 0 UU Test Results 4 8 Axial Strain - 12 Sample 203- Sample 204-6 Sample 203-4 16 Sample Depth Description and Cell or Undrained (ft) Classification Confining Shear Stress Strength (ksf) (ksf) 203-4 14.5 Lean CLAY (CL) 1.9 0.8 203-6 24 Lean CLAY (CL) 2.4 2.0 204-6 24 Fat CLAY (CH) 2.4 1.2 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D2850 UU TRIAXIAL TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-6a Page 531 of 1059 B-33 of 97 Brown and Caldwell Project No. 01-52-0721 3.0 Sample 2.5 0.5 pc' UU Test Results 4 8 Axial Strain - 12 16 Sample Depth Description and Cell or Confining Undrained Shear (ft) Classification Stress Strength (ksf) (ksf) 402-4 15 Lean CLAY (CL) 1.9 3.7 403-4 15 Fat CLAY (CH) 1.9 5.1 403-6 25 Sandy Lean CLAY 3.0 0.8 (CL) 403-8 35 Fat CLAY (CH) 3.6 0.9 Project: City of San Luis Obispo Water Reuse Project Test Method ASTM D2850 UU TRIAXIAL TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-6c Page 532 of 1059 B-34 of 97 M M M M M M M M M M M M M M M M r M M CM111, �GNYI 1[Lryj 9LU4k VAIil-1j= IVti a BM Q -yW, 116 1 14ID (tll 4[>eq WYO d.ISW 0241. 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IS. 20 - IT - 0 - - - � , 0.1 LL c Y. r ® © (D ®yam Ill ® - qQ 1 gtp� ±l Ee - QP�e �` ��� s'P GOO Y }n ;1 nx 3 i R;I G 3 8 ss 3 I 1 Qk o , r t -- tIzTgT r gg a x n Lt p ti RS oQ a3 qg s Igo Y�$ AS m R o i m $ J A I N � 16A m o � I �n I I 4y l3 9 ry LEI ELEVATION (meters) OleLL10tB0Ylp rr1lWr '�, �r �tl1CiXpXIC CO"L YEeR�OYClCY ibT 01 M Mde.] 811 WSC 5.0 Results and Findings Figure 5-3 Cross Section Transect Lines Map B'? B 7 B-10 B-5�`'�i 00 B-8 B-9 B-14 B-11 R B-13 B B-1'S B-16 B B-12 B-17 C (�B-19 "�, B - B-21 San Luis Ranch Well No. 2a B-2 o B-18R B-22 B-23 B-24 B-29 C' ob 0 0.25 0 B-32 I B-31 n OB-33 B-34 A' Remedial Investigation Report City of San Luis Obispo Legend Cross Section Transect Maximum Tetra chloroethyl ene (PCE) Concentration MCL > 5.0 ug/L Q Non -Detect < 2.5 pg/L 2.5-5.0pg/L 5.0 - 10.0 pg/L 10.0 - 20.0 pg/L >_ 20.0 pg/L Note: MCL - Maximum Contaminant Level ug/L - microgram per liter 5-12 Page 534 of 1059 B-36 of 97 U) C C LL 70 C (1) Of O U U) 3 S "WooA ~a Z b 2 il�� yi u�W3 O Q NQ� L.L O C Q (0 � cm 0 Z Q) O > J mm _/om''� / `V V / _� a) O E>, a � U M ti 1-0 rn o4-- 0 o ci LO m co N C7 U) CD c C LL -n C m Of O U U) _3 S a m w w m o a. 'n ~ W ��+ �t ate• c N O J O 4 0 V MEN DONE] m q� (� Z V I J ❑■aPI bg C M~� Vf!� lei aoa u sEp¢ ui b Q i M ti LO rn o4-- 0 o 00 cO m co LO a� c� U) CD c C LL _0 C c� N ry O Q w V 0 0 •"0 &Jtw. 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EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/23/22 BOREHOLE ID: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC) C 5 Lithologic Description a A r (depth interval in feet) a 3 x x x (o-I ) Artifical Fill (1-2) Clay (from CPT). x x x (2-4) Clayey Silt (from CPT), (4-6) Sandy Silt (t'rom CPT►. (6-8) Silty Sand (from CPT). (9-12) Gravelly Sand with Clay; brownish yellow; fine to coarse sand; angular to subrounded, poorly sorted gravel to 1.5-inch diameter. 10 YR 6/6 GM D (12-13) Clayey Sand with Gravel; brownish yellow; fine to coarse sand; gravel to 0.7.; 10 YR 6/6 SC inch diameter. 03-16) Sandy Clay trace gravel; dark yellowish brown: hard clay; mostly fine to mediLn - sand; trace coarse sand and fine gravel. IOYR4/4 CL ' (16-19.5) Sandy Silt and Clayey Silt (from CPT, no sample rccovcry). x X (19.5-20) Clayey Sand with Gravel; yellowish brown; coarse, subangular and angular ill ii ;; sand; fine gravel, soft clay. 10 1'R -5'8 SC' (20-24.5) Sandy Silt and Clayey Silt (from CPT; no sample recovery). Page 542 of 1059 10 YR 5/6 CL B-44 of 97 Page 2 / 3 CLEAT II - IIARRIS C1iG GEOLOGISTS SAP. LVIS OBISPO, C.% EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/23/22 BOREHOLE ID: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC ► 3 Lithologic Description (depth inteval in feet) (24.5-28) Sandy Clay with Gravel; yellowish brown; soft to very soft clay: tine to coarse. subangular to subrounded, poorly sorted sand, fine, angular to subrounded gravel to. I0 YR S/6 CL 0.9 (28-31.5) Sand (from CPT; no sample recovery). 30 N x 1.2 (31.5-32) Clayey Sand trace Gravel; brownish yellow; very soft clay; coarse, rounded to subrounded quartz, metavolcanic sand; fine, subrounded to rounded quartz, metavolcanic gravel clasts. 10 YR 6/6 SC /e, (32-36) Clay trace Sand; brownish yellow; very hard clay; trace fine sand. Ill YR 6/6 CL 35 0.2 (36-37) Sandy Silt and Clayey Silt (from CPT; no sample recovery). Y X (37-38) Clayey Sand trace Gravel; yellowish brown; very soft clay; coarse sand: trace 10 YR 6/6 SC subangular to subrounded gravel. (38-39) Sandy Clay; yellowish brown; soft clay; fine to medium, very well sorted sand. 10 YR 5/6 CL (39-40) Sandy Clay trace gravel; brownish yellow; soft to very soft clay, fine to coarse, 10 YR 6/6 CL 40 0.5 very poorly sorted, angular to subangular sand. 10 YR 5/6 CL (4041) Sandy Clay with Gravel; yellowish brown; soft to very soft clay; fine to coarse sand, angular to subangular gravel. IO YR 6/6 CL (41-44) Clay trace sand: brownish yellow; firm clay; trace fine sand. 45 (44-45.5) Sand with Clay trace gravel; yellowish brown; mostly coarse, subrounded to subangular, moderately well sorted sand; trace tine grave) to 0.5-inch diameter. 10 YR 5!4 SP-SC (45.547) Clay trace Sand: brownish yellow; soft clay; trace mostly tine sand. 10 YR 6/6 CL (4748) Clayey Sand trace Gravel; brownish yellow; mostly coarse, rounded to 10 YR 6/8 SC 0.5 subangular, sand; hard clay, trace subrounded to rounded gravel to 0.75-inch diameter. x x (48-51.5) Sand (from CPT; no sample recovery). 50 Page 543 of 1059 B-45 of 97 Page 3 / 3 CLEAT11-IIARRIS /CHG GEOLOGISTS Ar 1 U IR 0815P0. C•% EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/23/22 BOREHOLE ID: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rid- TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC ) Gt c 5 = a r s Lithologie Description CL M ' - (depth inteval in feet) 3 X \ x (51.5-521 Clayey Sand trace Gravel; brownish yellow. mostly coarse, rounded to 10 YR 016 TIC—subangular, sand: hard clay; trace subrounded to rounded gravel to 0,75-inch diameter. (52-57) Mostly Sand ( Crom CPT). 55 C e 1 went to S I beet. Water Sample was collected at >b teet. Direct Push refusal at 52 feet Page 544 of 1059 B-46 of 97 Page I / 3 CLEATII-IIARRIS /C'HG GEOLOGISTS \ SAN IUIS OBISPO, C.1 EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/31/22 BOREHOLE ID: B-24 SAMPLER TYPE: Macrocore MCA LOCATION: Prado Road BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WS0 = E a a I v o Lithologic Description (depth interval in feet) 3 X X (0-11 Artifical Fill (asphalt/road base) (1-2) Clayey Silt (from CPT). ` X (24) Sandy Silt (from CPT). � X X (4-6) Silty Clay (from CPT). 5 (6-8) Clay (from CPT). x (8-16) Clay trace sand, yellowish brown; hard clay; trace fine to coarse, subr� undrd >and 10 ui 10 YR 5/6 CL 15 (16-17) Clay and Silty Clay (from CPT; no sample recovery). X X X 07-17.5) Clay trace Sand; yellowish brown; soft to fine clay: trace fine to coarse sand. 10 YR 5/6 CL V/ 10 YR 5/6 CL (17.5-20) Sandy Clay trace Gravel; yellowish brown, very hard clay; fine to coarse, 0.2 poorly sorted sand; trace subangular to subrounded gravel to 0.5-inch diameter. 20 (20-23) Clay trace Sand; yellowish brown; hard clay; trace subrounded and subangular, very well sorted coarse sand. i n 1'R 5/6 CL (23-23.5) Sandy Clay trace gravel; brownish yellow; firm clay; fine to coarse sand, truer fine subrounded to subangular shale and metavolcanic gravel. (23.5-24) Gravelly Clay with Sand; brownish yellow; soft to firm clay; fine to coarse 10YR6/8 CL 10 YR 6/8 CL sand: fine subrounded gravel. 25 X X X (24-26) Sandy Silt and Clayey Silt (from CPT: no sample rf59'*'c2t45 of 1059 B-47 of 97 Ct.EAT ll-11ARRIN /('NG GEOLOGISTS \�- sus tins oetsro, c.. EXPLORATORY BORING LOG Page 2 / 3 PROJECT: SLO PCE DATE: 3/31/22 BOREHOLE ID: B-24 SAMPLER TYPE: Macrocore MC5 LOCATION: Prado Road BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC) v C. o. Lithologic Description (depth interval in feet) 3 (26-27) Sandy Clay trace gravel; yellowish brown; firm clay, fine to coarse sand; line X subrounded gravel. l0 YR 5/8 CL >> (27-28) Gravelly Clay with Sand, brownish yellow; very hard clay; litre to coarse 10 YR 6/6 CI_ sand; subangular to rounded gravel to 0.75-inch diamater. (28-31) Clay and Silty Clay (from CPT; no sample recovery). X \ ail - (31-32) Clayey Gravel with Sand; dark yellowish brown, firm clay; fine to coarse 10 YR 4/6 GC o �r sand; subangular to subrounded. mostly volanic gravel clasts to 0.75-inch diameter. \ \ (32-34) Clay and Silty Clay (from CPT; no sample recovery). (34-39) Clayey Gravel with Sand; yellowish brown; soft clay; fine to coarse sand. ' fine, subrounded to subangular volcanic, shale, metavolcanic gravel to 0.5-inch diameter. 10 YR 5/8 GC �' • ` • • (3940) Clayey Sand with Gravel; brownish yellow; soft clay; fine to coarse sand: I 0 YR 6/8 SC tine, subrounded to subangular volcanic, shale, quartz gravel to 0.5-inch diameter. -1l I (4042) Sandy Silt (from CPT; no sample recovery). X X X (4243) Clayey Sand with Gravel; brownish yellow, soft clay; fine to coarse sand. 10 YR 6/8 SC fine, subrounded to rounded volcanic and quartz gravel to 0.5-inch diameter. (4345) Clayey Sand with Gravel; yellowish brown; soft to very soft clay; fine to I 0 YR 5/8 SC coarse, poorly sorted sand; subrounded to angular volcanic, shale, and chen gravel to 0.5 inch diameter. -1 (4547) Sandy Clay trace gravel; yellowish brown; firm clay; fine to coarse sand; tract 10 YR 5/8 Cl- subangular to subrounded fine gravel. (4748) Sandy Clay; brownish yellow: very hard clay; mostly fine to medium sand, iracc 10 YR 6/8 CL coarse sand. (48-50) Sandy Silt and Clayey Silt (from CPT; no sample recovery). x a ,11 Page 546 of 1059 10 YR 5/8 Page 3 / 3 f/\ C.LEATII-IIARRIN / CHG,- GEOLOGISTS SAFW 1'U13 Obispo, C•, EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/31/22 BOREHOLE ID: B-24 SAMPLER TYPE: Macrocore MC5 LOCATION: Prado Road BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC) � C ��, a n. a 3 C U a. Lithologic Description (depth interval in feet) 55 60 65 0.0 0.0 10 YR 5/8 SC 1 (50-50.5) Clayey Sand with Gravel; yellowish brown; sots clay; fine to coarse. subangular to subrounded, poorly sorted sand; gravel to 0.6-inch diameter. (50.5-52) Sandy Clay; brownish yellow; very hard clay; mostly fine to medium sand. (52-56) Clayey Sand with Gravel; brownish yellow; soft clay; fine to coarse, subrounded to rounded, poorly sorted sand; subrounded to subangular, sliale and volcanic gravel clasts to 0.8-inch diameter. (56-60) Clay trace sand; brownish yellow; soft clay; trace mostly fine sand. (60-66) Sandy Silt (from CPT). CPT went to 66 feet. Water Sample was collected at 63 feet. Direct Push refusal at 60 feet 10 YR 6/8 CL 10 YR 6/8 SC 10 YR 6/8 CL Page 547 of 1059 B-49 of 97 <� NEFR tr 3�—w„ N Wd —Z — 03LLOld 3WLL 5ZOZ 5Z LL G— 03LLOld ava SN3A rG— 3WtlNtl n � o- s LI w b O J J JLLJ I Nt o 'o o a g< LO .� S ww� cx p �Ie a i m O m o w as mum N J w m Om u N l a All l ON O - to M 0 W a5� et O iE U O n Q N m z N p N ¢ i O No❑ W o O o 0 I N 2 O ] W 91 N i 133diS V83nolH Hinos xx a 3NAn �IH L 9 29 _ P 99 � w9 0 9 iw 9 w �I O N v� �o K W J w O Z Ln I W ¢ ry� Q n m W O a � a � El N N I OP m I N I g„ s m a` 0 o m sI? d _ \cl r- GP� � m o w 9 U N � N N w z J 0 Q � C a` o � O - O o � Q m N a s e D. nnoom O Y Uf^00�0�>Q o m00 LO rQZ 'S I.j� �L�OZ g Y U N I .. i_ S� .L�7 00 w Nln m 0 o m M ei W Z W> 2 x x q J O t0 N � a °� N °� O Q o°i of oio of co vi co m v m L° In a O � N M M H f U O _ mfaO lnmµ^ N r O a� a a a a ul r^ r r r r r � N � ul ul ul Ln ul = U1 N O> O (D m O W a0 N N O m ° U00 W u�0 W � 0�0 W Z N N N N N N N N N N N N N N N M a I m m m m N¢ a = N N N a� �N I eH°Lx EER � Wd —Z - O3l101d 3WLL SZOZ SZ LL G- —Old ava SN3AMKM'G- 3W—sn I a X I oi a6 o L Ld W �b3 C O U O ''p� S(83 � �$ rn c Q J E uo cis 4 z� y � °$ g�S o u d W fn Z s ELEVATION (FEET) W a o X esg@a o o ¢ �E M J Q Q m i_II p (J O .gpg&� M m K m m'I o � � � C o W 4� 9 IVI _x� g u c Q H - o.o��a - E d c m O o • U` E E E Q O O 11 J d' IV IL K O W E" o - n o Gib E as v w N m U u 66 2 0 Z _ > .E O a g v n Y n Ix Q o m u ve-- - o m 3 -58 o m E of ECz'o UPEz_gE J rff� �l' Ly O o. t o v FL •m m -m$ v s a N 6 oN x a - .vaa £'69+ZII '-IS '11,9'6l ? N v m O d O m _ N p H m O O C U 7 O O n < N 3 O N O Y O � O Z � N \ d 0 Q W O � a _ _ _ i• _ ui W vi � ro V _ E - Z _iF e E NE c o N N E EU N m ; E 9 Ed E- 3E �• v�iEz z3 w Ovo A gE �. p J o u- y .. 3 E 0 O N E a g O p p tOn - a s a m Z'`o s = a m o d o r v o I r I l E r l I la I rrrrr������r�r O O O t o.- m Qn mCs C a m m m c°5 i i o X L O V C p( L .Nn rad 5 ; v' C Z'69+6I I '^IS 'Ia Sal e N a 6\° E N pE 0 rc - N % M O •_ _ � c N c,i c ooaa m N 3 o o a x ra o �"a B wvrn `v v a .3 DOjPd N 3 C y U O � 433J) NOI1VA313 d g = _ c o o m I mat m-a a c v 0 0 - i cv o m N L p - N 0 C N r N NnoM D_ M TE Y U(^O w�1 Q . QLHO ^ Z z M M H (V M C § Go W pp NNE .P't Z o a m zW>2 - m Lo Q LL� O 0-) Nt Lo ^ W LL b o S� ELEVATION (FEET) q in o_ 0 EU Rn O_ W >u E E E E E E E L E a uE E E fy )1 Ja I& I5 I 1i =I N O. Mnmm pMp Y m > Q M M Z Z s W p p N N ii t m ZW>2 E _ Ei w E _ ¢z E E E I I I I I I I I I (1333) N011YA313 o' � ' z W 0 0 'o L L� °c U O o d � W � cz c 'o+ W J p O o q m O m m U a Q Ld Ld o — 'o 0 m N ry 11 o c o 0 O o • p CD o q U Q 0 d o m W J r N L y N a N = 3 m a c o c O E � c V O_ O N c a 4 d 0 L O r a � O N O U C Y � O ✓ p U C U U a p 0 o O J a 0 ¢ \ 30 o N o m N O Q vi z 0 (ri r-� m a o •c r n •- C m E 9 q aD - V c_ Mr N U I c M q p I co mo I 0 mM O •- _ 0 O C L c Q O O C O I N � - � ; Y p � a 0o a t o m x rn m a � II m n a I'd c y v m ; a p O � N O - m m o m L 0. U q d a m q c a a cv O p =� O O •_ rn« a m � Q m ¢ LV ¢ H N M Q O Z - I Mo ¢� 1 �N 1 eH°Lx EER � Wd —Z - ml101d 3WLL SZOZ SZ LL G- —Old 3Ltl0 SN3AMK11'G- 3mNmsn I o X I tl s g p o z LLJ x G 6 d c p W W �O dp z� U Lj W [n s m y a g� O c � z o ELEVATION (FEET) o •o m o W ire S s o m o a w tT LLJ z� z. 0 LL ag� B C - O i O O m -oN U O Q (' U O C a ✓ Q O - L� O y v m 3 d d' IV F IL o W O w =O U o� U 66 2 0 Z = 7JE y 30 9 O g x o _iL V g �a o)o V O `o_ O O o( o( ( a ) JW )`)Q f Wf ' a 3 o ( f f f I'i' I� O c d o - N J m 2 J Z w Q ry Q 25 m _ _ L6 Ld ri ZD d 6'O9NI I ^IS '18 ,0'O3 e o- &B r y - E 3— cc—Ezz camc + C C a p N -oam E E E l N a di N O O r` Pr O U m ��a�¢e sp N m S 5 rEr JQ _-EN& IyOo 'v p Nix '•' E'er'/Yw g Ef c ,•I' vwidc c ,•' c .- v z�'- o a E LO ._ O m a s c� of )m Ic Y J_ Y I I I I I I( d c 1 ao E;S c o � eufl Vad - N % M p C •- 6'99+911 'o1S 'la ,0£91 _ - •- - EW m u �� ������������o �v C E E O OMad N p O m B 3 m n v y aa.o-n-rn E ^� 0 0 �3 O ° > o v _ x KO �U c j - (1331) NOIIVA313 ? rnv`r a mcv 6 V v m O 3 o a '�v N N a m p El E rnE o3 7 C c r k nNo. QLFO e e Y U(O �p �1Q M M izz Z Z H N M 4 E t W pp NNE �•t Z IX 5 0 o Sy ) a m Mi`W Zw>m ¢� �N I eH°Lx EER � Wd —Z - O3l101d 3WLL SZOZ SZ LL G- —Old 3Ltl0 SN3AMK11'G- 31WNmsn I o X I o�tl s c a o z^ LLJ X o 'o N°I 6 a'3SLa c o+ c w O W O F o O U Q Z do z= a W (f) k X z e 8tlS g o J Ld Lo S "ggg a p O z l m s > 8Js$ o o o a All m FW o „ E'g ELEVATION (FEET) co p m LLJ g O o Q H ✓a - o a v a to O�� a m c m W' o `o O c — O °m o p O U p in in o ° m < J J `II p t m " d - rn L 0 � d d •3 O d' N F w o IL M O ° = O 2 O Z _ O a Jo a a � 0 y O_ m a o V 3 4 m 0 E + Z c a o d m O c m 4 o a. o a E ° Ow m 8 O V _ x W `o d d o m `o w cn Bull 91H c j o ~ O 0'££+SS 'RIS T_ c U o o N O o = 3 :F o c Q N Fa wC> + o, o, m ui ro r ao a� a (1333) NOliVA313 ELEVATION (FEET) o y oo m m �5 y m n` °m m �� a •; � N m Nr O O oa m a 'o < �o E `m um n or m < < rc w — m M t°i1 FpsF E V �L"' o O a5 w Z N 3 V C �L z � � w � C C V1 �•_ ° m N O W a o u •3 � E I � x ° N ; rn m y C O H q p •N .N.. L N m m ., B m N m m (133J) NOliVA313 o a g N a c - o m ' Ll U m y o m 0 E o a � o a w v 8 N 'o 0 6 •_ ° c m om (7 �_ Mnp�p OMp •oa a � ` � CJ Y D >Q (n m o e e t 9 MM OOOO m N M 4 IX Sy 5 0 W pp NNE p•t Z o a c° ZW>2 - i csi cgi H E - i n O I - soli tlNd N�x 0'S9+LII '^IS 'll ,9'IZ _ - E GROUP SYMBOLS AND NAMES Graphic / Symbol Group Names Graphic / Symbol Group Names Well -graded GRAVEL Lean CLAY GW Lean CLAY with SAND Well -graded GRAVEL with SAND Lean CLAY with GRAVEL CL SANDY lean CLAY SANDY lean CLAY with GRAVEL co 00 Poorly graded GRAVEL O o GP GRAVELLY lean CLAY O o e 0 0 Poorly graded GRAVEL with SAND GRAVELLY lean CLAY with SAND Well -graded GRAVEL with SILT SILTY CLAY GW-GM SILTY CLAY with SAND WeGRAVEL with SILT and SAND SILTY CLAY with GRAVEL CL-MIL SANDY SILTY CLAY • Well -graded GRAVEL with CLAY (or SILTY CLAY) SANDY SILTY CLAY with GRAVEL . GW-GC Well -graded GRAVEL with CLAY and SAND GRAVELLY SILTY CLAY (or SILTY CLAY and SAND) GRAVELLY SILTY CLAY with SAND o� Poorly graded GRAVEL with SILT SILT O GP -GM SILT with SAND O Poorly graded GRAVEL with SILT and SAND SILT with GRAVEL ° MIL SANDY SILT SANDY SILT with GRAVEL �o O Poorly g GRAVEL with CLAY SILTY graded O O GP -GC (or Poorly graded GRAVEL with CLAY and SAND GRAVELLY SILT o (or SILTY CLAY and SAND) GRAVELLY SILT with SAND SILTY GRAVEL ORGANIC lean CLAY GM ORGANIC lean CLAY with SAND O SILTY GRAVEL with SAND ORGANIC lean CLAY with GRAVEL OL SANDY ORGANIC lean CLAY SANDY ORGANIC lean CLAY with GRAVEL CLAYEY GRAVEL GC GRAVELLY ORGANIC lean CLAY p a CLAYEY GRAVEL with SAND GRAVELLY ORGANIC lean CLAY with SAND O SILTY, CLAYEY GRAVEL ORGANIC SILT GC -GM ORGANIC SILT with SAND O SILTY, CLAYEY GRAVEL with SAND ORGANIC SILT with GRAVEL OL SANDY ORGANIC SILT SANDY ORGANIC SILT with GRAVEL Well -graded SAND SW GRAVELLY ORGANIC SILT Well -graded SAND with GRAVEL GRAVELLY ORGANIC SILT with SAND Poorly graded SAND Fat CLAY Sp Fat CLAY with SAND Poorly graded SAND with GRAVEL Fat CLAY with GRAVEL CH SANDY fat CLAY Well -graded SAND with SILT SANDY fat CLAY with GRAVEL SWSM GRAVELLY fat CLAY Well -graded SAND with SILT and GRAVEL GRAVELLY fat CLAY with SAND Well -graded SAND with CLAY (or SILTY CLAY) Elastic SILT SW -SC Elastic SILT with SAND Well -graded SAND with CLAY and GRAVEL Elastic SILT with GRAVEL (or SILTY CLAY and GRAVEL) MH SANDY elastic SILT Poorly graded SAND with SILT SANDY elastic SILT with GRAVEL SPSM GRAVELLY elastic SILT Poorly graded SAND with SILT and GRAVEL GRAVELLY elastic SILT with SAND Poorly graded SAND with CLAY (or SILTY CLAY) ORGANIC fat CLAY SPSC ORGANIC fat CLAY with SAND Poorly graded SAND with CLAY and GRAVEL ORGANIC fat CLAY with GRAVEL (or SILTY CLAY and GRAVEL) OH SANDY ORGANIC fat CLAY SILTY SAND SANDY ORGANIC fat CLAY with GRAVEL SM GRAVELLY ORGANIC fat CLAY SILTY SAND with GRAVEL GRAVELLY ORGANIC fat CLAY with SAND CLAYEY SAND ORGANIC elastic SILT SC ORGANIC elastic SILT with SAND CLAYEY SAND with GRAVEL ORGANIC elastic SILT with GRAVEL OH SANDY elastic ELASTIC SILT SILTY, CLAYEY SAND SANDY ORGANIC elastic SILT with GRAVEL SCSM GRAVELLY ORGANIC elastic SILT SILTY, CLAYEY SAND with GRAVEL GRAVELLY ORGANIC elastic SILT with SAND ORGANICSOIL PT PEAT ORGANIC SOIL with SAND — ORGANIC SOIL with GRAVEL OUGH SANDY ORGANIC SOIL SANDY ORGANIC SOIL with GRAVEL COBBLES COBBLES and BOULDERS GRAVELLY ORGANIC SOIL BOULDERS GRAVELLY ORGANIC SOIL with SAND DRILLING METHOD SYMBOLS Auger Drilling H ® Dynamic Cone Rotary Drilling a or Hand Driven ® Diamond Core FIELD AND LABORATORY TESTS C Consolidation (ASTM D2435) CL Collapse Potential (ASTM D5333) CP Compaction Curve (ASTM D1557) CR Corrosion, Sulfates, Chlorides (CTM 643; ASTM D4972, ASTM G187, ASTM D4327) CU Consolidated Undrained Tiiaxial (ASTM D4767) DS Direct Shear (ASTM D3080) El Expansion Index (ASTM D4829) M Moisture Content (ASTM D2216) OC Organic Content (ASTM D2974) P Permeability (ASTM 5084) PA Particle Size Analysis (ASTM D422-63 [2007]) PI Liquid Limit, Plastic Limit, Plasticity Index (ASTM D4318) PL Point Load Index (ASTM D5731) PM Pressure Meter PP Pocket Penetrometer R R-Value (CTM 301) RS Torsional Ring Shear (ASTM D6467) SE Sand Equivalent (CTM 217) SG Specific Gravity (AASHTO T 100) St. Shrinkage Limit (ASTM D427) SW Swell Potential (ASTM D4546) TV Pocket Torvane UC Unconfined Compression - Soil (ASTM D2166) Unconfined Compression - Rock (ASTM D7012) UU Unconsolidated Undrained Triaxial (ASTM D2850) UW Unit Weight (ASTM D4767, ASTM D7263) VS Vane Shear (AASHTO T 223-96 [20041) -200 200 Wash (ASTM D1140) SAMPLER GRAPHIC SYMBOLS ® Standard Penetration Test (SPT) (2" O.D.) mStandard California Sampler (2.5 O.D.) eModified California Sampler (Y O.D.) TShelby Tube M Piston Sampler Rock Core Grab Sample Bulk Sample Other (see remarks) WATER LEVEL SYMBOLS Q First Water Level Reading (during drilling) Y Static Water Level Reading (short-term) 1 Static Water Level Reading (long-term) INYeh and Associates, Inc. Geotechnical • Geological • Construction Services REPORT TITLE LEGEND FOR SOIL CLASSIFICATION PROJECT NAME Prado Road Bridge Widening DATE 10/1 SHEET B-55 of 97 ROCK GRAPHIC SYMBOLS ® IGNEOUS ROCK ® SEDIMENTARY ROCK METAMORPHIC ROCK BEDDING SPACING Descriptor Thickness or Spacing Massive > 10 ft Very thickly bedded 3 to 10 ft Thickly bedded 1 to 3 ft Moderately bedded 3-5/8 inches to 1 ft Thinly bedded 1-1/4 to 3-5/8 inches Very thinly bedded 3/8 inch to 1-1/4 inches Laminated < 3/8 inch WEATHERING DESCRIPTORS FOR INTACT ROCK Diagnostic Features Chemical Weathering -Discoloration -Oxidation Mechanical Weathering Texture and Solutioning and Grain Boundary Body of Rock Fracture Surfaces Texture Solutioning Descriptor Conditions General Characteristics Fresh No discoloration, not oxidized No discoloration No separation, intact No change No solutioning Hammer rings when crystalline or oxidation (tight) rocks are struck. Slightly Discoloration or oxidation is Minor to complete No visible separation, Preserved Minor leaching of Hammer rings when crystalline Weathered limited to surface of, or short discoloration or intact (tight) some soluble rocks are struck. Body of rock distance from, fractures- some feldspar crystals are dull oxidation of most surfaces minerals may be noted not weakened. Moderately Discoloration or oxidation All fracture Partial separation of Generally Soluble minerals Hammer does not ring when Weathered extends from fractures usually surfaces are boundaries visible preserved may be mostly i rock is struck. Body of rock s throughout; Fe -Mg minerals discolored or leached slightly weakened. are "rusty' ; feldspar crystals oxidized are "cloudy" Intensely Discoloration or oxidation All fracture Partial separation, rock is Altered by Leaching of Dull sound when struck with Weathered throughout; all feldspars and surfaces are friable; in semi -arid chemical soluble minerals hammer; usually can be broken Fe -Mg minerals are altered to discolored or conditions, granitics are disintegration may be complete with moderate to heavy manual clay to some extent; or oxidized- surfaces disaggregated such as via pressure or by light hammer chemical alteration produces in situ disaggregation (refer to are friable hydration or argillation blow without reference to planes of weakness such as incipient or grain boundary conditions) hairline fractures or veinlets. Rock is significantly weakened. Decomposed Discolored of oxidized Complete separation of Resembles a soil; partial or Can be granulated by hand. throughout, but resistant rain boundaries ?disaggregated) complete remnant rock structure Resistant minerals such as minerals such as quartz may may be preserved; leaching of quartz may be present as "dikes". be unaltered; all feldspars and soluble minerals usually stringers' or Fe-Mq minerals are complete completely altered to clay Note: Combination descriptors (such as "slightly weathered to fresh") are used where equal distribution of both weathering characteristics is present over significant intervals or where characteristics present are "in between" the diagnostic feature. However, combination descriptors should not be used where significant identifiable zones can be delineated. Only two adjacent descriptors shall be combined. "Very intensely weathered" is the combination descriptor for "decomposed to intensely weathered". CORE RECOVERY CALCULATION (%) E Length of the recovered core pieces (in.) x 100 Total length of core run (in.) ROD CALCULATION (%) E Length of intact core pieces > 4 in. x 100 Total length of core run (in.) IN ROCK HARDNESS Descriptor Criteria Extremely Hard Specimen cannot be scratched with pocket knife or sharp pick; can only be chipped with repeated heavy hammer blows Very hard Specimen cannot be scratched with pocket knife or sharp pick; breaks with repeated heavy hammer blows Hard Specimen can be scratched with pocket knife or sharp pick with heavy pressure; heavy hammer blows required to break specimen Moderately Specimen can be scratched with pocket knife or sharp pick with light or moderate Hard pressure; breaks with moderate hammer blows Moderately Soft Specimen can be grooved 1/6 in. with pocket knife or sharp pick with moderate or heavy pressure; breaks with light hammer blow or heavy hand pressure Soft Specimen can be grooved or you ed with pocket knife or sharp pick with light pressure, breaks with light to moderate hand pressure Very Soft Specimen can be readily indented, ggrooved, or gouged with fingernail, or carved with pocket knife; breaks wtf light hand pressure FRACTURE DENSITY Descriptor Criteria Unfractured No fractures Very Slightly Fractured Lengths greater 3 ft Slightly Fractured Lengths from 1 to 3 ft, few lengths outside that range Moderately Fractured Lengths mostly in range of 4 in. to 1 ft, with most lengths about 8 in. Intensely Fractured Lengths average from 1 in. to 4 in. with scattered fragmented intervals with lengths less than 4 in. Very Intensely Fractured I Mostly chips and fragments with few scattered short core lengths REPORT TITLE LEGEND FOR ROCK CLASSIFICATION Yeh and Associates, Inc. PR aJECT NAME do Road Bridge Widening Geotechnical • Geological • Construction Services DATE SHEET 10/10/2024 1711--- ccn1.ad B-56 of 97 LOGGED BY BEGIN DATE COMPLETION DATE HAMMER TYPE BORING NUMBER R. Hooke 1/18/22 1/19/22 140-lb Autotrip 22RC-01 FINAL BY BOREHOLE LOCATION (Lat/Long or North/East and Datum) SURFACE ELEVATION J. King --/-- 139.0 ft DRILLING METHOD BOREHOLE LOCATION (Offset, Station, Line) WEATHER NOTES 4" SSA/Mud Rotary/3.75" HQ Core 10.50' Rt. Sta. 112+69.2, "PRA" Line Cool, partly cloudy DRILLER LOCATION DESCRIPTION BACKFILLED WITH Geo-Ex Subsurface Exploration West side of bridge,10' west of fence Monitoring Well DRILL RIG GROUNDWATER DURING DRILLING AFTER DRILLING (DATE) TOTAL DEPTH OF BORING CME 55 Track -Mounted Rig READINGS 20.5 ft See Report I 1 100.0 ft C L t C ° Z m C0 co 0 o m c -0 L E ° DESCRIPTION 8 E a T o �,` Remarks w a a)n o�aZ 3 3 0 0 "o 0 W W (p 20 N O N j O O N ('� •p p �` U Lin = N >N T' ASPHALT CONCRETE. Grouted Solinst Level Logger installed on 1 to top 1/20/2022 6" AGGREGATE BASE. SANDY lean CLAY (CL); brown; moist; A few to little GRAVEL; (ALLUVIUM). 137 2 3 135 4 5 Hard. -200 (13% G, 37% S, 50% F) 1 5 17 100 17 98 ;;4 _5PP 6 133 6 11 7 131 8 CLAYEY GRAVEL with SAND (GC) brown; moist. 9 ou 0 129 10 Loose; fine to medium, subrounded to -200 (29% G, 27% S, 44% F) 2 8 13 78 12 2.75PP o subangular GRAVEL. 5 PI (42 LL, 19 PL, 23 PI) 11 ° 8 127 12 ° 13 0 ° 0 0 125 14 15 0 — ---- CLAYEY GRAVEL (GC); medium CR �H = 6.93, r = 722 ohm -cm, 3 9 21 100 25 98 dense; brown; moist; fine to medium, 8 SO4 = 40 mg/kg, Cl- = 15 mg/kg) 123 16 a , o subangular GRAVEL. 13 Bentonit Chips 17 0 121 18 ° 19 ° 119 20 0 CLAYEY SAND with GRAVEL (SC); Switched to mud rotary 4 2 13 100 medium dense; brown; moist; fine to 5 21 medium, subangular to subrounded 8 GRAVEL. 117 22 Sand around 23 slotted screen 115 24 25 (continued) PROJECT NAME Yeh Associates, Inc. Prado Road Bridge Widening UMBER and 216 323 BORING NUMBER Geotechnical • Geological • Construction Services 22RC-01 REVISION DATE SHEET 9/12/2022 r jr B-57 of 97 L6 40 89-8 ti 10 Z 133HS ZZOZ/Z W6 31V4 NOISIA3b S33TA13S UOTIO ISUOD o iLIOt20ioaf) o jR:)!U Z)j0aj) •aui sajr,iaossV pug uaA • - 21zz a39vm ONNOO £Z£-9�Z a3awnN l03road uiuepiM a piJB peob opeid 3wVN ioamld (WO-wqo bbb' L = J '00•L = Hd) 2jo (Id 6L Id OZ ` 16£) Id (d %9s 'S %bb .o %0) OOZ- s�l3ewat{ m -O 7 m 3OS x p (panuguoo) -;;os'pajaq;eamAj9sua;ul '(30NV-13H NVOSIONV2id) 'sdlgo uel pue Velq'uos tian 'pasodwooap'umojq '(3NO-LS IVIO) NOo2j Q:JV1N3w1(13SV13w 99 b9 E9 Z9 Ls 09 6b 8b Lb 9b 917 bb Eb Zb Lb Ob 6E 8E LE 9E 9E b£ ££ Z£ L£ 0£ 6Z 8Z LZ 9Z SZ v m 98 L8 68 L6 £6 96 L6 66 LOL EOL 90L LOL 60L LLL ELL m m < 0 � OOL Bros .9/09 Ob OL 3a b/Os 6 00V. L9 sz £L ZL L 8 x 'l3AVI:IE) popunagns 'wnlpaw o; oul� aoea;'}}gs tian PIS oaq m, —°Rs wnlpaua'(lVIO ueal.l4NVS O) I (OS) l3AVIJO qPm dNVS k3A O NOIldNOS34CD ' � •' . G) 0 CD ? dd9 E 66 9Z OOL ss 8£ 8L L L L v _ ddgf L 6Z b6 u 6 8 9 9 x dd9L'0 x (A gy m CD 7 1 06 a v � z� (D 1 ZE n K N. ? m JOOL ;(1 0 c sz W o p 9L £ W o 9 A =3 B m O fD r c/) 3 o '�° C. W Ao Z 00 00 �LO am K N z cu oa 22 Z m m ZO i J W ~ W O L co P (7 DESCRIPTION 3 Of 0 d O N U0 cn J a`> 0 F= i Z CC 7 X C (0 a N O CO O w o N O m p O N of o C� a,' O N 0 0 C) L a) ., C o a L c aS L V) U) O r C = E m CJ a1 C O °- N Remarks 83 81 79 77 75 73 71 69 67 65 63 61 59 57 55 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 Black; moderately weathered; moderately soft. METASEDIMENTARY ROCK (Claystone) (continued). Intensely weathered; intenselyy fractured; clay seams up to 1/4". Fracture plane at 65 degrees. METASEDIMENTARY ROCK (GRAYWACKE); gray; intensely weathered; moderately soft; intensely to moderately fractured; clay infill fractures. Weathers to sandy lean CLAY (CL), vertical trace fractures with iron stains and calcite. Highly sheared zone, closed fractures. METASEDIMENTARY ROCK (CLAYSTONE); black; very soft; very intensely fractured; very sheared, clay matrix - hard. Block of GRAYWACKE SANDSTONE from 73 to 73.5. Clay matrix - hard. Intensely weathered; very sheared. (continued) 150/4" REF/4" 26 102 ' .:_'... ' Sand to bottom of hole Switched to Wireline Coring CU UU UC UC 25 19 9 12 114 127 124 4.5PP >4.5PP 4.5PP Q Q Q Q Q Q Q Q Q Q Q Q Q 2 88 62 3 100 78 4 100 68 5 100 24 6 100 56 7 92 30 Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22R - 1 REVISION DATE 9/12/2022 SHEET B-59 of 97 N ZO i J W 53 51 49 47 45 43 41 ~ W ❑ 85 86 87 88 89 90 91 g2 93 94 95 96 97 98 99 m L coP 2 U DESCRIPTION METASEDIMENTARY ROCK (Claystone) (continued). Block of GRAYWACKE SANDSTONE from 86.5 - 88.5. METASEDIMENTARY ROCK (GRAYWACKE); some 2 - 4" blocks, very intensely sheared zones. Gray; intensely to moderately weathered; moderately fractured. 1/2" clay seam, closed fractures. 3 Of C d O E�� fn J a`> i Z 7 X 7 ❑ (0 a N O CO O w o N O c0 p O N W 92 o C7 30 a,' ON 00 U❑ L a) �'U a L c aS L N (n O r C = ❑ 0 0 0 E m ❑ a1 . .':. '.. . ' C O °- ❑ N Remarks UC 8 94 38 9 94 35 10 31 31 39 37 35 33 31 29 27 25 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 11 Bottom of borehole at 100.0 ft bgs This Boring Record was developed in accordance with the Caltrans Soil & Rock Logging, Classification, and Presentation Manual (2010) except as noted on the Soil or Rock Legend or below. Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22R - 1 REVISION DATE 9/12/2022 SHEET B-60 of 97 LOGGED BY BEGIN DATE COMPLETION DATE HAMMER TYPE BORING NUMBER R. Hooke 1-19-22 1-20-22 140-IbAutotrip 22RC-02 FINAL BY BOREHOLE LOCATION (Lat/Long or North/East and Datum) SURFACE ELEVATION J. King --/-- 139.0 ft DRILLING METHOD BOREHOLE LOCATION (Offset, Station, Line) WEATHER NOTES 4" SSA/Mud Rotary/3.75" HQ Core 16.30' Rt. Sta. 114+56.9, "PRA' Line Sunny, warm DRILLER LOCATION DESCRIPTION BACKFILLED WITH Geo-Ex Subsurface Exploration East side of bridge, 10' south of ETW Grout DRILL RIG GROUNDWATER DURING DRILLING AFTER DRILLING (DATE) TOTAL DEPTH OF BORING CME 55 Track -Mounted Rig I READINGS Not measured 91.0 ft z0 o a5 _ 0 E CD o o . (D w rn t w Q = DESCRIPTION j CD a a � o > � N g N o Remarks w H a m C 0. E E 3 3 0 .�. N c D w 2 0 in in m m tY 2 U in �- U :YN 0 U) 0 0 8" ASPHALT CONCRETE. 1 6" AGGREGATE BASE. CLAYEY SAND with GRAVEL (SC); brown and red; B 137 2 moist; fine to medium, subangular GRAVEL; red color possibly decomposed bricks; (ARTIFICIAL FILL). 3 135 4 5 CR (pH = 6.69, r = 1,257 ohm -cm) CLAYEY SAND with GRAVEL SC); medium dense; 12 8 26 100 9 110 dark brown; moist; (ALLUVIUM. 12 133 6 14 7 131 8 9 129 10 :•; Very loose. 13 P 2 83 P 11 2 127 12 13 125 14 15 Lean CLAY with SAND (CL); very stiff; brown; moist; CR �H = 7.30, r = 602 ohm -cm, 14 7 36 100 22 102 4.OPP trace fine GRAVEL. 15 SO4 = 81 mg/kg, Cl- = 7 mg/kg) 123 16 21 17 121 18 19 119 20 200 (1 % G, 23% S, 76% F) 15 4 15 100 2.5PP 7 PI (45 LL, 17 PL, 28 PI) 21 8 117 22 23 115 24 25 (continued) PROJECT NAME Yeh Associates, Inc. Prado Road Bridge Widening UMBER and 216 323 BORING NUMBER Geotedmical • Geological • Construction Services 22RC-02 REVISION DATE SHEET 9/12/2022 B-61 of 97 Z6 40 Z9-8 ti 10 Z ZZOZ/U/6 133HS 31V4 NOISIn3b S33TA13S AOTIOMISUOD • IEO120101f) • lg:)!U Z)10a� ZO-ONZZ a39vm JNIN09 •aui sajr,iaossV £z£-9�z a3awnN l33road pug uaA • uiueplm a piJB peob opeid 3wVN 103rOad (panuguoo) 99 v9 98 E9 Z9 L8 4S 8Z 4Z dd9'b< 004 6V Z4 4Z 'umojq :pJeH 09 68 6b 8b 46 Lb 917 £6 b4 Z4 no dd9'4 Z04 bZ 004 9Z 8 OZ 'MIS 917 bb 96 £b Zb L6 4b 9 (Id EZ 'ld ZZ 'll SO Id 9 (d %46 'S %6 'O %0) OOZ- ddO' 6 004 04 £ 64 _umojq pej 'Mils wrnpaw `(10) ,kV10 ueel Ob 66 — — — — — 6E 8E 404 LE 9£ £04 94 Z4 '4NVS asJeoo :: .: 96 8Z 004 LZ 8 84 0; aui; 'umojq 'asuep wnlpew :(OS) ONVS A3AV10 ' 9£ --------------------- b£ 904 ££ Z£ L04 4£ l4 8 (d %08 'S %OZ'J %0) OOZ- dd9L•Z 004 64 b L4 'umojq pai :,qI;s Am !(l0) ONVS WM AV10 veal 0£ 604 — — — — — — — — — — — — — — — — — — — — — 6Z 8Z 444 LZ 9Z E44 8 L 176 8Z 004 94 9 94 'umojq '9sool '(OS) dNVS k3.1V10 ' (�0 N 5 a oo p CD o o pZ �v ��' c v o i 3 3 @ °om r- m �ewa v CD CDs fD '� CDo NOIldRiOS34 m2. CDCD s0 o 3CL O cc 3 3 0 r z (n0-) Ao D 00 o C:) N rn L^' N �✓ w CY) O cu z z v w N O N N L CL N m 3 z z 0 0 J M M N z > W _ o �+ g 0 DESCRIPTION o 5 ` ._ {�pp U E -i Z a p. co (A CO a N m 0 -0'�\.. n 0 m c Z' 0 W o of � 3 N 2 c> O1 N ._ D o n C ` f6 to Y '0 = °) C a r °' o Remarks C c.> 83 81 79 77 75 73 71 69 67 65 63 61 59 57 55 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 SANDY lean CLAY with GRAVEL (CL); hard; brown; fine to medium, subangular GRAVEL. ---------------- SANDY lean CLAY (CI ); hard; brown. 22 24 31 50/1" 81/7" 100 21 103 4.5PP UC CU 23 29 90/12"100 40 50/6" >4.51PP METASEDIMENTARY ROCK (CLAYSTONE); black/brown; intensely weathered; soft; very intensely fractured; with 4 to 6 inch blocks of GRAYWACKE; (FRANCISCAN MELANGE). Black/gray; 35 to 65 degree fractures, 1" seam of soft clay. 45 degree fracture. GRAYWACKE block from 67' to 68'. METASEDIMENTARY ROCK (GRAYWACKE); gray; intensely weathered; moderately soft; intensely to very intensely fractured; intermittent 6 inch layers of shale. Medium stiff clay seam from 77.2 to 77.5. (continued) 1 22 9 18 25 120 107 Q Q Q Q Q Q Q Q Q Q >< Q Q Q Q Q Q Q Q Q Q Q 2 90 43 3 4 100 24 68 20 5 28 0 6 28 16 7 16 16 Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22Rc-02 REVISION DATE 9/12/2022 SHEET B-63 of 97 L6 40 t,9-8 v bo b ZZOZ/U/6 133HS 31V4 NOISIn3b S33TA13S uOTIOMISuOD o [LIO12010af) o lg:)!U Z)10a� zo-jazz a39vm 9Nlaoa •aui sajr,iaossV £z£-9�z a3awnN 103road pug uaA • uivaplm a piJB peob opeid 3wVN 103rONd KL 5Z ELL ZLL LZ OLL 6Z 60L 90L L£ LOL 90L E£ 50L VU 5E EOL ZOL LE LOL OOL 6E 66 86 Lb L6 96 fib 56 -molaq jo pua6al �ooa jo b6 5b llos ay; uo pa;ou se;deoxe (0 LOZ) lenueW uol;ejuasaid pue 'uol;eoglsse1O '6u166o1 Noob V llos suejIleO ay} E6 g;lM aouepj000e w padolanap seM pJooab 6wJoa slgl Z6 Lb s6q }} O' L6 }e alogaaoq;o wol;o8 L6 O O6 6b O 68 �ooa pain}oeal O •paJeags �(lasua1w :uos tian :paJaq;eaM �(lasu91UI 88 65 gjpA sa6ualleyo pue s6nld eldglnw �loelq '(3NO1S).V1O) NOO2J AZ:IV1N3w143SV13w 6ldwes;o 6ouegan}slp 'aldwes O ewej xa ul jonjs 9 uq, 661 alge}/6nld > <8 L b8 8 L8 'g;dap wnjuoo of poi Ino 6uglnd O 98 E5 •(p9nugjuo6) 9L 9L L (91oeMi -E)) NooO j MJV1N3lNl(132Vl3w 58 c)v N5 g0oo �; kJ W o W o v m G)K m p m r 0 ' C o 0 i N N 3 '00 fD _0 m < s�l�ewaa (p CD CD C C a fD oCD L c o NOIldRiOS34 ==, m s o. cn 0 a 00 S �i O Z 3 S (CD 0 7 (nm Ao D 00 oN N rn L^O' N W W 0 co z z 0 w N O N N L Rock Core Photos Project No. 216-323 Prado Road Bridge Widening April 4, 2022 22RC-01 Run 1 55.3-56.5' 22RC-01 Run 2 56.5-61.5' 22RC-01 Run 3 61.5-66.5' 22RC-01 Run 4 66.5-71.5' 22RC-01 Run 5 71.5-76.5' IN Page 563 of 1059 B-65 of 97 Rock Core Photos Prado Road Bridge Widening Project No. 216-323 April 4, 2022 w , t rJ 1 22RC-01 Run 6 76.5-81.5' 22RC-01 Run 7 81.5-86.5' 22RC-01 Run 8 86.5-91.5' 22RC-01 Run 9 91.5-96.5' 22RC-01 Run 10 96.5-100' IFW ",ta i+ 1 IN Page 564 of 1059 B-66 of 97 Rock Core Photos Prado Road Bridge Widening 22RC-02 Run 1 61.5-66.5' Project No. 216-323 April 4, 2022 } x, r<:AIW i 22RC-02 Run 2 66.5-71.5' V.-. 1 Iry 4 22RC-02 Run 3 71.5-76.5' 22RC-02 Run 4 76.5-79.0' JA Page 565 of 1059 B-67 of 97 Rock Core Photos Prado Road Bridge Widening ram; �F "�'`"� ., � ''add � `• - ' L - 22RC-02 Run 5 79.0-81.5' 22RC-02 Run 6 81.5-84.0' Project No. 216-323 April 4, 2022 VA Page 566 of 1059 B-68 of 97 Rock Core Photos Prado Road Bridge Widening V OF 22RC-02 Run 7 84.0-86.5' 22RC-02 Run 8 86.5-91.0' Project No. 216-323 April 4, 2022 VA Page 567 of 1059 B-69 of 97 rn 0 4- 0 00 LO a� O) (u Lu H Q00 O Y �O N O a2 w p ] W W . o[GC W 2r1 oc a Ln H J CL LLI ~ LLIH Wm O �� f4 Z cc z o Z M m w0 w_M UO Yn QO -0 OM- O,1 W.� OY O wW =a rev a-4 =-4 m J � LL O ~ Q o O C v •� V O � U_ O O y �.r �y U VV U U /O bZ/bZ/OL 9IO'�bZOZ l.2ivnNVf bn H3.1) J.21V2191I H31. 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Geotechnical • Geological • Construction Services Mechnical Sieve Analysis Test Methods: ASTM D6913, D2487, D4718 illProject Name I Prado Road Bridge Project No. 1 216-323 1 Project Manager I J. King Tested By 1 I. Blackburn/R. Atliano Checked By I J. King ITesting Date 1 9/12/2017 SUMMARY OF RESULTS USCS WaterGravel Sample Depth Sand Fines Classification AASHTO Boring No. Content Dio (mm( Dao Imm� Dso Imm( Deo (mm1 Cu Cc No. (ft) (Y.)(%) &Soil Classification NO(%0) Description Well Graded Sand BS-A Creek 0-2 0.0% 46% 53% 1% 0.76 1.96 4.29 6.61 8.70 0.80 with Gravel (SW) brown, moist, subrounded gravel Well -Graded GRAVEL with Sand BS-B Creek 0-2 0.0% 56% 42% 2% 0.74 2.66 5.93 7.90 10.80 1.20 (GW) brown, moist, subrounded gravel Well -Graded SAND BS-C Creek 0 0.0% 43% 55% 2% 0.63 2.11 4.08 5.40 8.60 1.30 with Gravel (SW) brown, moist, subrounded gravel BS-D Creek 0-2 0.0% 2% 83% 15% 0.17 0.30 0.37 - Silty SAND (SM) bank brown, moist Page 570 of 1059 B-72 of 97 ill GRADATION CHARTS Boring No.: BS-A Sample No.: Creek USCS Classification: Well Graded Sand with Gravel (SW) <-------------- Gravel -------------- > 1 <------------------------- Sand ---------------------- > 1 <--------- Fines --------- > 1 3" 2" 1" 3/4" 1/2" 3/8" No.4 No. 10 No. 20 No.40 No. 60 No. 100 No. 200 100 90% 80% 70% 60% N a 50 40% 30% 20% 10% oo/ ��IIIIII■�I�IIIIII�II�IIII■� IIIIIl1 ��IIIIII■�I�IIIII��II�IIII■� IIIIIII���IIIIII■�I�IIIII��I IIIII■� IIIIf11����11111■�I�II111��11�1111■� IIIIIII���III��1■�I�IIIII��II�IIII■� IIIIIIIq��lll11►■�I�IIIIIq�11�1111■� IIIIIII���IIIIII� �I�IIIII��II�IIII■� IIII111���111111■ \I�II111��11�1111■� IIIIIII���IIIIII■ �1�1��11�1111■� IIIIIII���111111■ �,INaIla1111■� 100 10 1 0.1 0.01 Particle Diameter (mm) Boring No.: BS-B Sample No.: Creek USCS Classification: Well -Graded GRAVEL with Sand (GW) 100% 90 80% 70% 60% .S a 50% e` 40% 30 20% 10% 0°/ <-------------- Gravel ---------- > 1 <------------------------ Sand -------------------- > I <--------- Fines --------- > 1 3" 2" 1" 3/4" 1/2" 3/8" No. 4 No. 10 No. 20 No. 40 No. 60 No. 100 No. 200 IIIt11��111111■■I�IIIIIgH11�1111■� IIIIIII����IIIIII■■IIIIIII��II�IIII■� IIIIIII�� �III111■■I�II111��11�1111■� IIIIIl1��a111111■■IIII111��1111111■� IIII111���111111■�IIII111��1111111■� IIIIIIIq��llll�l■�IIIIIIIgH1111111■� IIII111���11111►�■IIII111��11�1111■� IIIIIII���IIIIIIti1�11111��1 l IIIII■� I111111���111111■\��lI111��1I IIIII■� IIIIIII���IIIIII■�Illli�:p�!!!p1111■� o„ 100 IN 10 Particle Diameter0.1 0.01 (mm) Page 571 of 1059 B-73 of 97 ill GRADATION CHARTS Boring No.: BS-C Sample No.: Creek USCS Classification: Well -Graded SAND with Gravel (SW) ��No. 200 00% .0, 80 % 70% rn 60% 0 a 50o/c a 40% 30% 20% 10% 0% 100 1111111 Ism 1 111111NE11111 MM6,10M.".1111M 10 1 Particle Diameter (mm) Boring No.: BS-D Sample No.: Creek bank USCS Classification: Silty SAND IA 0.1 0.01 <-- ----Gravel >I < and >I < Fines >� o 3 12' /8" No.4 No.10 No.20 No.40 No.60 No. 10 No.200 100 /o 90% 80% 70% m 60% c .N a 50% a 40% 30% 20% 10% 0% IIIIq■�IIII�A71 IgHIlIl111■■ IIII■■IIIIIII■■i 111■■IIIIIII■■ IIII■■IIIIIII■■I�I►11■■IIIIIII■■ IIII■■IIIIIII■■Illll�i■■IIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIIIq■�111111■■IIII111l�HIIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIII■■11111■■■111111■■11111■■■ IIII■■IIIIIII■■IIIIIIIHHIiN1111■■ 111■■■IIII IIIIIII■■IIIIIII■■ 100 10 1 0.1 0.01 Particle Diameter (mm) Page 572 of 1059 B-74 of 97 ill GRADATION CHARTS Boring No.: BS-C Sample No.: Creek USCS Classification: Well -Graded SAND with Gravel (SW) ��No. 200 00% .0, 80 % 70% rn 60% 0 a 50o/c a 40% 30% 20% 10% 0% 100 1111111 Ism 1 111111NE11111 MM6,10M.".1111M 10 1 Particle Diameter (mm) Boring No.: BS-D Sample No.: Creek bank USCS Classification: Silty SAND IA 0.1 0.01 <-- ----Gravel >I < and >I < Fines >� o 3 12' /8" No.4 No.10 No.20 No.40 No.60 No. 10 No.200 100 /o 90% 80% 70% m 60% c .N a 50% a 40% 30% 20% 10% no/ IIIIq■�IIII�A71 IgHIlIl111■■ IIII■■IIIIIII■■i 111■■IIIIIII■■ IIII■■IIIIIII■■I�I►11■■IIIIIII■■ IIII■■IIIIIII■■Illll�i■■IIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIIIq■�111111■■IIII111l�HIIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIII■■11111■■■111111■■11111■■■ IIII■■IIIIIII■■IIIIIIIHHIiN1111■■ 111■■■IIII IIIIIII■■IIIIIII■■ o 100 10 1 0.1 0.01 Particle Diameter (mm) Page 573 of 1059 B-75 of 97 8C 7C 6C 2C 1C CH or OH 00, CL or OL 4 • it oF O MH or OH ML or OL CL- L 0 0 10 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT, LL Boring Number Sample ID Depth (ft22RC-01 Symbol Test M) Fines LL PL PI Classification 2 10.0 • 12 44 42 19 23 CLAYEY GRAVEL with SAND (GC) 22RC-01 6 30.0 m 29 56 39 20 19 SANDY lean CLAY (CL) 22RC-02 15 20.0 A 76 45 17 28 Lean CLAY with SAND (CL) 22RC-02 19 40.0 * 91 45 22 23 Lean CLAY (CL) 24E-01 1 2.5 O 22 72 44 21 23 Lean CLAY with SAND (CL) 24E-01 3 10.0 0 75 49 17 32 Lean CLAY with SAND (CL) 24E-02 5 2.5 O 14 62 33 16 17 SANDY lean CLAY (CL) 24E-02 7 10.0 A 79 51 20 31 Fat CLAY with SAND (CH) 24E-03 9 2.5 ® 21 54 45 21 24 SANDY lean CLAY (CL) 24E-03 12 15.0 (D 70 40 20 20 Lean CLAY with SAND (CL) Y r �I� Yeh and Associates, Inc. L I=A= Geotechnical • Geological • Construction Services ATTERBERG LIMITS PROJECT NAME PROJECT NO. Prado Road Bridge Widening 216-323 REVISION DATE PROJECT MANAGER 10124124 1 J. Kin PREPARED BY CHECKED BY SHEET R. Hooke J. Ross L 1 of B-76 of 97 C) w m c ^ o �&) LO / \0 _^ m ±� R� _ \ �\ �W | 0 3 / ��®( \ \ � @ J/ ƒca )D / ) ± 7 4 %d 7© ) } a.0 §J—q &} m ` E E < cn CN ,E 2 2 CD § § « 4 ! j 2ƒa g .> e < § _ / k /E/\ ~ o ~ < U w ~ \) { » / a§ ) \ \g ) / 0 LJ} 2 \ƒ _ u \ n f Q � / /)f'n e ) °L)( 8 ) ) = 2 q q y � c reeri•a ..e••.r •• CTM , Yeh • Associates • Brown Lean CLAY w/Sand Expansion _ Pressur Specimen Designation Compactor •• - (psi) •, I �� -- Exudation - (psi) ® •• I • Exudation • . • • I • I • • ®-- HeightAfter Compaction ® • 1 ®-- Expansion Pressure (psf) Stabilometer • 2000 ®® • -- Turns Displacement ��-- Content (%) Wet Density (pcf) DensityMoisture Dry • 1 • ®�� - MMMMMMMMMM MMM Conoco MMMMM 1 MM�������MMMMMM 11 1 �MMM MMMMMMMMMMMMMMMMM MMMM MMMMM MMMMME 11 MMMMM MMMM MMMMM 11 MMMMMMMMMMMM _MMM Mwpm 1 MMMM MMMM 11 1 11 11 11 �11 11 .11 11 :11 Page 576 of 1059 B-78 of 97 5 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 33.4°, c'= 0.12 ksf - -Total Stress 4 - - Eff. Stress at User Defined Strain / / a - Consolidation Stress: 2.1 ksf / Consolidation Stress: 3.6 ksf Consolidation Stress: 5.0 ksf 7 8 9 10 Boring Number 22RC-01 Trial ID A B C Sample Number 5 zO Liquid Limit --- --- --- o Specimen Depth 26.0 ft a Plastic Limit --- --- --- w USCS Classification Sandy lean CLAY (CL): Plastic Index --- --- --- a red brown, moist y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 31.6% 28.1% 26.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 90.4 95.8 98.0 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 99% 100% 100% Cell Pressure, ksf 10.8 12.2 13.7 Z Void Ratio 0.86 0.76 0.72 Back Pressure, ksf 8.6 8.7 8.7 Diameter, in 2.42 2.40 2.40 Consolidation Stress, ksf 2.1 3.6 5.0 Height, in 5.00 4.80 4.68 } a Deviator Stress @ Failure, ksf 2.2 4.0 5.8 2 Axial Strain @ Failure, % o'1F, ksf 3.1 3.0 3.1 5.5 5.1 8.0 Water Content, % 28.1% 26.6% 25.4% w Dry Unit Weight, pcf 95.8 98.0 99.9 rn o'3F, ksf 0.7 1.5 2.2 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.76 0.72 0.69 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) w � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked by: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 577 of 1059 B-79 of 97 7.0 N Y 6.0 Cl) 0 5.0 T 0 II 4.0 N N .. 3.0 to L0 2.0 lE d 1.0 00 0 ri 4.5 b 4.0 T 0 II 3.5 0 @ 3.0 N 2.5 L to 2.0 c tL 1.5 W 10 Consolidation Stress: 2.1 ksf Consolidation Stress: 3.6 ksf Consolidation Stress: 5.0 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) w 3.0 N Y 3 2.5 4 II 2.0 d L 3 H 1.5 d L 0 1.0 L 0 c 0.5 a� 0.0 c -0.5 ' 0 2 A 22RC-01 B 22RC-01 C 22RC-01 4 6 8 10 12 14 Vertical Strain (%) #5 25.0 ft Sandy lean CLAY (CL): red brown, moist #5 25.0 ft #5 25.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 578 of 1059 B-80 of 97 8 7 6 5 N Y c 4 M b 3 i a 2 1 0 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 15.3', c'= 0.52 ksf - -Total Stress - - Eff. Stress at User Defined Strain - Consolidation Stress: 4.3 ksf Consolidation Stress: 5.8 ksf Consolidation Stress: 7.3 ksf 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 p' = (61+a'a)/2, ksf Boring Number 22RC-01 Trial ID A B C Sample Number Run 2 z Liquid Limit --- --- --- o Specimen Depth 57.5 ft a Plastic Limit --- --- --- w USCS Classification CLAYSTONE: brown v Plastic Index --- --- --- a U. Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 19.2% 20.3% 19.9% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 113.6 108.9 109.7 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 107% 100% 100% Cell Pressure, ksf 11.5 13.0 14.4 Z Void Ratio 0.48 0.55 0.54 Back Pressure, ksf 7.2 7.2 7.2 Diameter, in 2.36 2.46 2.49 Consolidation Stress, ksf 4.3 5.8 7.3 Height, in 5.12 4.90 4.75 } a Deviator Stress @ Failure, ksf 3.0 4.3 5.0 2 Axial Strain @ Failure, % 6'1F, ksf 2.0 5.4 3.2 8.1 1.5 10.1 Water Content, % 20.3% 19.9% 19.6% w Dry Unit Weight, pcf 108.9 109.7 110.2 CO) G'3F, ksf 2.3 3.8 5.1 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.55 0.54 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) w � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 579 of 1059 B-81 of 97 6.0 w N Y 5.0 M b 4.0 b II y 3.0 d L to 2.0 L 0 m a> 1.0 00 0 2.4 M b 2.2 b II 2.0 0 @ 1.8 N 1.6 L N 1.4 c Il 1.2 W 10 Consolidation Stress: 4.3 ksf Consolidation Stress: 5.8 ksf Consolidation Stress: 7.3 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) w 2.5 N Y G 2.0 II 1.5 3 N N ;u 1.0 a d L ro 0.5 a� j 0.0 C -0.5 0 2 4 6 8 10 12 14 Vertical Strain (%) A 22RC-01 #Run 2 57.5 ft CLAYSTONE: brown B 22RC-01 #Run 2 57.5 ft C 22RC-01 #Run 2 57.5 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 580 of 1059 B-82 of 97 8 7 6 5 N ci Y 4 b 3 i a 2 1 0 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 33.7', c'= 0.07 ksf - -Total Stress - - Eff. Stress at User Defined Strain / Consolidation Stress: 4.3 ksf 0000 Consolidation Stress: 5.7 ksf / Consolidation Stress: 7.2 ksf 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 P' = (6 t+(T'3)/2, ksf Boring Number 22RC-02 Trial ID A B C Sample Number 20 zO Liquid Limit --- --- --- o Specimen Depth 45.0 ft a Plastic Limit --- --- --- w USCS Classification Lean CLAY (CL): red Plastic Index --- --- --- a brown, moist y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 23.8% 21.5% 20.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 102.0 106.5 108.2 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 98% 100% 100% Cell Pressure, ksf 11.5 13.0 14.4 Z Void Ratio 0.65 0.58 0.56 Back Pressure, ksf 7.2 7.2 7.2 Diameter, in 2.42 2.42 2.44 Consolidation Stress, ksf 4.3 5.7 7.2 Height, in 5.00 4.78 4.65 } a Deviator Stress @ Failure, ksf 3.7 6.2 9.0 2 Axial Strain @ Failure, % o'tF, ksf 3.0 5.0 3.0 8.6 3.3 12.5 Water Content, % 21.5% 20.6% 19.8% w Dry Unit Weight, pcf 106.5 108.2 109.8 rn o'3F, ksf 1.4 2.4 3.5 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.58 0.56 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) fn � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 581 of 1059 B-83 of 97 10.0 Y 9.0 M 8.0 b 7.0 b 6.0 y 5.0 L .. 4.0 to 0 3.0 1° 2.0 N 0 1.0 00 0 ri 4.0 b 3.5 b II 3.0 0 2.5 N N N L to 2.0 c a 1.5 ti W 10 Consolidation Stress: 4.3 ksf Consolidation Stress: 5.7 ksf Consolidation Stress: 7.2 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) w 4.0 N Y 3.5 3 G 3.0 II 2.5 3 N 2.0 d L a 1.5 d L r0 1.0 a� 0.5 3 0.0 -0.5 ' 0 2 A 22RC-02 B 22RC-02 C 22RC-02 4 6 8 10 12 14 Vertical Strain (%) #20 45.0 ft Lean CLAY (CL): red brown, moist #20 45.0 ft #20 45.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 582 of 1059 B-84 of 97 16 / / - - Effective Stress Consolidation Stress: 5.7 ksf 14 - A Eff. Stress at Max. Obliquity: W= 37°, c'= 0.02 ksf / ._. _ ......... ........ Consolidation Stress: 7.2 ksf - - Total Stress / Consolidation Stress: 8.6 ksf 12 - } - Eff. Stress at User Defined Strain ...................... 10 - ............................... .......................... ..... w Y / N8 ................... .................. ................... ................... ................. ................... ................... ................... ................... 0 b bg ................................................................ u / a / 4 ................................................................................................... / 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 p' _ (6 f+a'3)/2, ksf Boring Number 22RC-02 Trial ID A B C Sample Number Run 3 zO Liquid Limit --- --- --- o Specimen Depth 73.0 ft a Plastic Limit --- --- --- w USCS Classification GRAYWACKE: olive, Plastic Index --- --- --- a highly fractured y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 25.1% 20.7% 20.1% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 106.5 108.0 109.3 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 116% 100% 100% Cell Pressure, ksf 12.1 13.7 15.1 Z Void Ratio 0.58 0.56 0.54 Back Pressure, ksf 6.5 6.5 6.5 Diameter, in 2.46 2.50 2.51 Consolidation Stress, ksf 5.7 7.2 8.6 Height, in 5.01 4.79 4.68 } a Deviator Stress @ Failure, ksf 6.2 10.5 18.5 2 D Axial Strain @ Failure, % O'fF, ksf 3.1 8.2 3.1 14.1 6.8 24.6 Water Content, % 20.7% 20.1% 19.6% w Dry Unit Weight, pcf 108.0 109.3 110.2 rn G'3F, ksf 2.1 3.6 6.1 N Saturation, % 100% 100% 100% w Tested By: ND ND ND uJ Void Ratio 0.56 0.54 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) w � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab wChecked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 583 of 1059 B-85 of 97 25.0 w N Y M 20.0 b b 15.0 N N 10.0 N 0 0.0 0 ri 4.5 b 4.0 T b II 3.5 0 @ 3.0 N 2.5 L to 2.0 c a 1.5 W 10 w 4.0 N Y 3.5 3 G 3.0 II 2.5 3 N 2.0 d L a 1.5 d L r0 1.0 a� 0.5 3 0.0 Consolidation Stress: 5.7 ksf Consolidation Stress: 7.2 ksf Consolidation Stress: 8.6 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) -0.5 ' 0 2 A 22RC-02 B 22RC-02 C 22RC-02 4 6 8 10 12 14 Vertical Strain (%) #Run 3 73.0 ft GRAYWACKE: olive, highly fractured #Run 3 73.0 ft #Run 3 73.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 584 of 1059 B-86 of 97 4 3 0 1 0 - *- - Effective Stress A- - Eff. Stress at Max. Obliquity: V= 16.4', c'= 0.34 ksf - Ar- -Total Stress - *- - Eff. Stress at User Defined Strain / - Consolidation Stress: 0.7 ksf Consolidation Stress: 1.4 ksf Consolidation Stress: 2.8 ksf / 1 2 3 4 5 6 7 8 p' _ (a'1+(3 a)/2, ksf Boring Number 24E-01 Trial ID A B C Liquid Limit --- --- --- Sample Number 2 z o Specimen Depth 5.0 ft a Plastic Limit --- --- --- w USCS Classification Lean CLAY w/Sand 2 Plastic Index --- --- --- a (CL): brown, moist (0 Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- L) Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 28.1% 30.2% 29.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 94.8 92.7 93.7 Strain Rate, %/min 0.02 0.02 0.02 g Saturation, % 97% 100% 100% Cell Pressure, ksf 10.8 11.5 13.0 Z Void Ratio 0.78 0.82 0.80 Back Pressure, ksf 10.1 10.1 10.1 Diameter, in 2.42 2.47 2.49 Consolidation Stress, ksf 0.7 1.4 2.8 Height, in 5.00 4.89 4.77 } a Deviator Stress @ Failure, ksf 1.1 1.6 2.2 2 :D Axial Strain @ Failure, % 6'tF, ksf 0.8 1.4 1.9 2.4 4.1 4.0 Water Content, % 30.2% 29.6% 28.5% w Dry Unit Weight, pcf 92.7 93.7 95.2 G'3F, ksf 0.3 0.9 1.7 Saturation, % 100% 100% 100% w Tested By: ND ND ND w w Void Ratio 0.82 0.80 0.77 Date Tested: 9/21/24 9/22/24 9/23/24 a Test Method: ASTM 4767 (modified for staged testing) Cn � Prado Road a Tested By: N. Derbidge LuChecked by: R. Hooke CONSOLIDATED UNDRAINED TRIAXIAL TEST Page 585 of 1059 B-87 of 97 ►w. N Y cn 2.0 b b 1.5 u N N L 1.0 in L 0.5 N 0 00 M 5.0 b 4.5 b 4.0 u 3.5 m N 3.0 N 2.5 co 4 2.0 'L a t� 1.5 W 10 y 1.2 Y G 1.0 n L 0.8 U) N N a 0.6 co 0.4 d 3 0.2 C 00 Consolidation Stress: 0.7 ksf Consolidation Stress: 1.4 ksf Consolidation Stress: 2.8 ksf 0 2 4 6 8 Vertical Strain (%) 0 2 4 6 8 Vertical Strain (%) 10 12 14 10 12 14 0 2 4 6 8 10 12 14 Vertical Strain (%) A 24E-01 #2 5.0 ft Lean CLAY (CL): brown, moist B 24E-01 #2 5.0 ft C 24E-01 #2 5.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST Page 586 of 1059 B-88 of 97 40 35 30 w Y 25 M b b 20 N N N i .+ y 15 O R y 10 G 0 61 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 22RC-01 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 3 ZO a Sample Depth: 64.0 ft a 44 (4.75mm) --- Plastic Limit --- USCS Classification: GRAYWACKE: bluish gray v 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.75 S. from T,, ksf --- Water Content, % 9.2% N W Dry Unit Weight, pcf 127.3 v 4200 (0.075mm) --- S. from PP, ksf --- wSaturation, % 73% 0 Void Ratio 0.35 Maximum Deviator Stress, ksf 35.2 W Diameter, in 2.41 Undrained Shear Strength, ksf 17.6 Height, in 3.89 } Axial Strain at Failure, % 9.9 Strain Rate, %/min 1.0 2 Cell Pressure, ksf 7.9 p Tested By: ND Date Tested: 3/4/22 N U) W ~ W Q W a Test Method: ASTM 2850 aProject: Prado Road Bridge Expansion u The specimen's length to diameter ratio was less than 2 Tested By: N. Derbidge, Cal Poly Geo-E Lab W Checked By: J. Cravens, Yeh and Associates UNCONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 587 of 1059 B-89 of 97 2.5 2.0 0.0 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 24E-03 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- W Sample Number: 10 Oz a Sample Depth: 5.0 ft a 44 (4.75mm) --- Plastic Limit --- Q USCS Classification: Lean CLAY (CL): dark brown, moist U 416 (1.18mm) --- Plasticity Index --- LL a 430 (0.6mm) --- *100 (0.150mm) --- Estimated Gs 2.75 S. from T, ksf --- Water Content, % 30.9% w Dry Unit Weight, pcf 87.3 v *200 (0.075mm) --- S from PP, ksf --- wSaturation, % 88% 0- Void Ratio 0.97 Maximum Deviator Stress, ksf 2.2 a Diameter, in 2.42 Undrained Shear Strength, ksf 1.1 Height, in 5.00 Axial Strain at Failure, % Strain Rate, %/min 15.0 1.0 Q Cell Pressure, ksf 0.7 Tested By: ND co Date Tested: 9/18/24 w w C9 Q W a Test Method: ASTM 2850 Prado Road Tested By: N. Derbidge Checked By: R. Hooke w UNCONSOLIDATED UNDRAINED TRIAXIAL TEST Page 588 of 1059 B-90 of 97 60.0 50.0 w 40.0 y Y b b 30.0 N N N i J o 20.0 5 N 10.0 0.0 Axial Strain, % Confining Stress: 0.0 ksf • Interpreted Point of Failure 10 12 14 16 o Boring Number: 22RC-01 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 5 ZO a Sample Depth: 73.5 ft a 44 (4.75mm) --- Plastic Limit --- USCS Classification: GRAYWACKE: olive 0 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.90 S. from T,, ksf --- Water Content, % 12.3% N u� Dry Unit Weight, pcf 124.0 v 4200 (0.075mm) --- S. from PP, ksf --- w Saturation, % 78% 0 Void Ratio 0.46 Maximum Deviator Stress, ksf 54.1 a Diameter, in 2.33 Undrained Shear Strength, ksf 27.0 Height, in 2.87 } Ix Axial Strain at Failure, % 0.9 Strain Rate, %/min 0.1 2 Cell Pressure, ksf 0.0 - p Tested By: ND Date Tested: 3/11/22 F W Q J Test Method: ASTM 2850 QProject: Prado Road Bridge Expansion U) !" Y Tested By: N. Derbidge, Cal Poly Geo-E Lab Checked By: J. Cravens, Yeh and Associates •=w- W UNCONFINED COMPRESSION TEST REPORT Page 589 of 1059 B-91 of 97 3.5 3.0 2.5 w y Y n 2.0 b b N N 1.5 N i r+ O 1.0 N G 0.5 0.0 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 22RC-02 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 2 ZO a Sample Depth: 67.0 ft a 44 (4.75mm) --- Plastic Limit --- USCS Classification: GRAYWACKE: olive 0 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.90 S. from T,, ksf --- Water Content, % 17.5% N W Dry Unit Weight, pcf 120.2 v 4200 (0.075mm) --- S. from PP, ksf --- wSaturation, % 100% 0 Void Ratio 0.51 Maximum Deviator Stress, ksf 3.1 a Diameter, in 2.30 Undrained Shear Strength, ksf 1.6 Height, in 5.02 } Axial Strain at Failure, % 1.5 Strain Rate, %/min 1.0 2 Cell Pressure, ksf 0.0 p Tested By: ND Date Tested: 3/4/22 W U) W W ;4 , Test Method: ASTM 2850 a 1 Project: Prado Road Bridge Expansion U Tested By: N. Derbidge, Cal Poly Geo-E Lab Checked By: J. Cravens, Yeh and Associates W d' UNCONFINED COMPRESSION TEST REPORT Page 590 of 1059 B-92 of 97 Unconfined Uniaxial Compressive Strength Test of Intact Rock Cores ASTM D7012 - 1.5.1 Method C: Uniaxial Compressive Strength of Intact Rock Cores Job No.: 216-323 Project: Prado Road Bridge Expansion F— V W Client: Yeh and Assoc., Inc. _ O Date: 3/6/2022 a Test Method: ASTM D7012 (1.5.3 Method C: Uniaxial Compressive Strength of Intact Rock Core Specimens) 0 Boring Number: 22RC-01 Sample ID: Run 4 CL Sample Depth: 70.5-71.0 ft N Classification: GRAYWACKE two E Moisture Condition: As Received H Moisture Content: N/A CL 0- a Unit Weight (pcf): 145.1 Dry Unit Weight (pcf): N/A Length/Diameter : 2.22 Comp. Strength (psi): 390 Specimen Length:Diameter within 'desireable' range of 2.0:1 to 2.5:1 per ASTM D7012 section 8.1.1 Moisture contents not measured Boring Number: 22RC-01 Sample ID: Run 9 CL M Sample Depth: 93.0-94.0 ft N Classification: GRAYWACKE Moisture Condition: As Received two N Moisture Content: N/A Unit Weight (pcf): 164.5 CL I Dry Unit Weight (pcf): N/A Length/Diameter : 2.42 Z n f� RIC _ �! ; P 4 Comp. Strength (psi): 6,130 y 6 !-�4. 411 -A ;-a Specimen Length:Diameter within 'desireable' range of 2.0:1 to 2.5:1 per ASTM D7012 section 8.1.1 Moisture contents not measured Page 591 of 1059 B-93 of 97 4 . u Z ---i � J p p O W U U 'E W m N O U co i � o)U U 3 d CD o Eo N oLL o D�� a) W U (n p , c m p J rn�p ii Q p O U N N e p O fn J m a) U� i O p m L fB Q O ir f6 a) (� O a> -p N L rn LO m O 0 TN VT J LO N D 5 3 (38S/4) *a _« now 3mA@ mBW! m ° ,§ }) «t ]� \ \ e m ° (D S �k _ $%g e< ))§ \§ ° )km ))\ , »/E §)§ /$§ , 02/ \LL/ )! ` 04 \) , kco j= § « E k-co m m — m b # m / _� \\ ° _ 0 \ LL k `t / / Mn \ 04 \ § ico\ @$ ƒ m ` § a2 \ coco () k \ N ^ o .\ (I j { 0 \ a) 2 // �e / ^ \\ CD 2 .= 2 $\ 04 )s j #{. k ¢f Q° 0 ■` 02 k \U 'a Cl) 2 §k _ >>ml k— cD � �� $ � �� § _ §@ _ wR G) b{ _ § 2/ J §Q » »$ S\ ° x0 § �\ ° ƒ/\ k) kk \ \\ \ aLL f \ , $a] 08 #a s \/0 Z' nƒ m £Q» 8 \U 2 0 o> 2n c 0g o§ ) ) k m N e ° ° p- (0 ` 7 k7 «g}pae +ƒ* 12_ §a m m D 0 q CY) m _ D _ � Line 1 Station 165 ft 1 D Shear -Wave Velocity Profile Velocity (ft./sec) N N W W is A Un Cn CT UI O (T O L" O CA O (T O UI O (21 P N U1 O CDO O O O O O O O O O C. C.O CD O O O CDO O O O OO O 0 1,800 ft/sc Velocity Layer at 25.4 ft o Interpreted as Bedrock Surface w b F lb 1C A O to b ,� r— D sC V T A m -� `m QO to �? T ' C a 3 o S II I� 3 0 4 I I D N zng V O r y H N N O O O - _ N O Based on SurlSeis MASW Processing and Modeling using 4-Layer Vs Model Figure ADVANCEB�CV•W. 3 Line 1 Station 415 ft 1 D Shear -Wave Velocity Profile Velocity (ft./sec) N N fJ w A A V1 VI a) al CT O O VI O CA O Cr O Cr O cn 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 = 0 i T Yj R ti Y L: r- T. `^ a O 1,780 ft/sc Velocity Layer at 34.3 ft m s 3 Interpreted as Bedrock Surface o C n a i oa a m g' N N Based on SurlSeis MASW Processing and Modeling using 4-Layer Vs Model Figure 4 ADVANCEF3aM905Z51*_CtQ•W. Page 596 of 1059 Aj consor CITY OF SAN LUIS OBISPO Draft Prado Road Interchange Project Retaining Wall Type Selection Report 05-SLO-101 PM 26.8/27.3 P I D 0516000105 July 2, 2026 PREPARED BY: Consor Point of Contact: Dace Morgan, PE 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95630 p: 916.368.9181 e: dace.morgan@consoreng.com PREPARED FOR: City of San Luis Obispo 919 Palm Street San Luis Obispo, CA 93401 Page 597 of 1059 Type Selection Revisions July 2, 2026 Draft Type Selection Memo Page 598 of 1059 Prepared by: Ashley Hanson, Retaining Wall Project Engineer Under the Supervision of: Scott McCauley, Lead Structure Project Engineer Submitted by QROFESSIONq�\ Ashley Hanson m fN o. C94887 s� CIVIL �F �F OF Ci�?� � l / QROFESSIONq�\ wScott McCauley No. C71495 CIVIL �P 9TF OF C 07/XX/2026 (916) 368-9181 Dace Morgan, Deputy Project Manager Date Consor North America, Inc. Telephone Page 599 of 1059 DRAFT Table of Contents Chapter 1 General Information ............................................ 1-1 1.1 Structure Type Selection..................................................................................................................1-1 1.2 Introduction.....................................................................................................................................1-1 1.3 General Description.........................................................................................................................1-2 1.4 Project History.................................................................................................................................1-3 1.5 Existing and Proposed Nearby Facilities...........................................................................................1-4 1.6 Funding............................................................................................................................................1-5 1.7 Impacts to Traffic.............................................................................................................................1-5 1.8 Staging and Contractor access.........................................................................................................1-5 1.9 Right of Way.....................................................................................................................................1-5 1.10 Hydraulic Considerations...............................................................................................................1-6 1.10.1 Floodplain...............................................................................................................................1-6 1.10.2 Scour.......................................................................................................................................1-6 1.10.3 Drainage.................................................................................................................................1-7 1.11 Geotechnical Considerations.........................................................................................................1-7 1.12 Seismic Ground Motion.................................................................................................................1-8 1.13 Liquefaction and Lateral Spreading Potential................................................................................1-9 1.14 Structure Layout............................................................................................................................1-9 1.15 Design Exceptions........................................................................................................................1-10 1.16 Retaining Wall Design Criteria......................................................................................................1-10 1.16.1 Corrosion...............................................................................................................................1-10 1.17 Utilities.........................................................................................................................................1-10 1.18 Environmental Studies and Permits.............................................................................................1-11 Chapter 2 Approach Retaining Walls ................................. 2-12 2.1 Preferred Structure Type Summary...............................................................................................2-12 2.2 Structure Type Alternatives...........................................................................................................2-12 2.2.1 Mechanically Stabilized Embankment (Preferred)..................................................................2-12 2.2.2 Conventional Retaining walls..................................................................................................2-12 2.3 Constructability..............................................................................................................................2-13 D218721CA.00 • April 2026 • Prado Road Interchange • City of SLuis Q Retaining Wall Type Selection ei pef 1059 DRAFT 2.4 Barriers...........................................................................................................................................2-13 2.5 Aesthetics.......................................................................................................................................2-13 2.6 Cost Estimate.................................................................................................................................2-14 2.7 Recommendation...........................................................................................................................2-14 Chapter 3 Retaining Wall Island ........................................ 3-15 3.1 Structure Layout............................................................................................................................3-15 3.2 Preferred Structure Type Summary...............................................................................................3-15 3.3 Structure Type Alternatives...........................................................................................................3-16 3.3.1 Mechanically Stabilized Embankment (Preferred)..................................................................3-16 3.3.2 Conventional Retaining walls..................................................................................................3-16 3.4 Constructability..............................................................................................................................3-16 3.4.1 Obstructions to MSE Reinforcement.......................................................................................3-16 3.5 Barriers...........................................................................................................................................3-17 3.6 Aesthetics.......................................................................................................................................3-17 3.7 Cost Estimate.................................................................................................................................3-17 3.8 Recommendation...........................................................................................................................3-17 APPENDIX A: Retaining Wall 35% Plans .......................... 3-1 APPENDIX B: Retaining Wall 35% Estimates ...................3-2 APPENDIX C: Retaining Wall Alternative Estimates ........3-3 APPENDIX D: GAD Approval Memo................................3-4 APPENDIX E: Approved BSDS..........................................3-5 APPENDIX F: Draft BDHS................................................3-6 APPENDIX G: Draft SPGR.................................................3-7 D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 2 Page 601 of 1059 DRAFT CHAPTER 1 GENERAL INFORMATION 1.1 Structure Type Selection Table 1-1 1 Project Identification Table 1-2 1 Retaining Wall Information and Cost Retaining RecommendedinCost Wall Name Wall Type Wall "RW1" MSE 2,783 $1,646,000 Wall "RW2" MSE 3,095 $1,939,000 Wall "RWY MSE 2,856 $2,194,000 Wall "RW4" MSE 3,162 $2,326,000 Wall "RW5" MSE 5,541 $3,626,000 Wall "RW6" MSE 6,283 $3,944,000 Wall "RW7" MSE 5,023 $3,136,000 Wall "RW8" MSE 26,280 $16,642,000 Wall "RW9 Island" MSE 11,457 $6,908,000 PROJECT TOTAL $42,361,000 1.2 Introduction The U.S. Route 101 (US 101)/Prado Road Interchange Project (Prado Road Interchange) is being developed by the City of San Luis Obispo (City). The purpose of the project is to extend Prado Road over U.S. 101 to connect with Dalidio Drive and reconstruct the existing U.S. 101 northbound on- and off -ramp connections to Prado Road in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the City of San Luis Obispo on U.S. 101 PM 26.8. The project limits extend from PM 26.8 to PM 27.3. The project is located within Caltrans District 5 in the City of San Luis Obispo, San Luis Obispo County. The project area is located within Township 31 South, Range 12 East, on the U.S. Geological Survey (USGS) San Luis Obispo, California 7.5-minute quadrangle. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-i Page 602 of 1059 DRAFT 1.3 General Description P 1, O, r yin 0 2 5 5 \Arles I 1 I Los Padres ` National orest /,5an Luis Obispo l% t. Grover Beach oceano Dunes state Vehicular tlecreation Area Figure 1-1 1 Vicinity Map Arroyo Grande D218721CA.00 a April 2026 a Prado Road Interchange a City of San Luis Obispo Retaining Wall Type Selection Report a Page 1-2 Page 603 of 1059 DRAFT Figure 1-2 1 Retaining Wall Locations A Total of nine (9) Retaining walls are proposed as part of the interchange improvements at the Prado Road Interchange. Eight (8) of the walls are at the approaches of the four bridge structures and the remaining wall is at the built up "Island" This type selection report discusses the recommended wall types for each of these (9) Walls and summarizes their approximate lengths and maximum retained heights. The preliminary project layout shown is Figure 1-2 highlights the location of the walls. Walls 5-9 are within Caltrans Right of way. General Plans of the walls are included in Appendix A. 1.4 Project History The US 101/Prado Road Interchange is a project that has been discussed, studied, and developed since the early 1990's. Over time, the project plan has progressed from an overcrossing to a full interchange and from a full interchange to the current overcrossing with northbound ramps. One of the reasons for the overcrossing/interchange was the potential development of the Dalidio property on the west side of US 101 between Madonna Road and Los Osos Valley Road (LOVR). Throughout the years, the Dalidio development took on many forms and land uses with many starts and stops as is common for development. The earliest planning document for the full interchange was a Project Study Report (PSR) prepared by Nolte and Associates for the City of San Luis Obispo and Caltrans in 1996. The PSR studied three alternatives for a full interchange: ➢ Tight diamond D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-iii Page 604 of 1059 DRAFT ➢ Spread diamond ➢ Spread diamond with a cloverleaf southbound off ramp Because of interchange spacing issues with Madonna Road, a southbound collector -distributor roadway on the west side of US 101 to link Madonna Road and Prado Road was proposed to address the limited weaving distance on southbound US 101. At the time of the 1996 PSR, one of the primary drivers of the project, the Dalidio development to the west of the project, did not move forward and there was no support from Caltrans HQ to approve a design exception for the interchange spacing between Madonna and Prado. Without developer funds to help offset construction costs and the Caltrans design exception hurdle, the Prado Interchange project laid dormant until the mid 2010's. In 2014, Coastal Community Builders (CCB) known as MI San Luis Ranch, LLC, initiated an application to develop the Dalidio property. The San Luis Ranch development would include housing, affordable housing, recreation, retail, and commercial spaces with an emphasis on Farm to Table to honor the agricultural history of the property. With the development moving forward, the need for an overcrossing at Prado Road became necessary once again. A 2018 Project Study Report/Project Development Support (PSR/PDS) noted that because of interchange spacing and forecast traffic needs, the 1996 solution of a full interchange with a collector -distributor was deemed invalid. Alternatives were advanced in the PSR/ PDS for the overcrossing and northbound ramps only. Subsequent traffic evaluations and the 2023 Traffic Operations Assessment Report (TOAR) amendment completed as part of the Project Approval and Environmental Document (PA&ED) supported designs for a refined overcrossing, northbound ramps, and a ramp terminal intersection. These recommendations are proposed to being advanced for final design and implementation. 1.5 Existing and Proposed Nearby Facilities US 101 is the principal north/south freeway/expressway on the Central Coast traversing the counties of Santa Barbara, San Luis Obispo, Monterey and San Benito within District 5. It serves local, regional and interregional travel needs, including business, recreation, tourism, journey -to -work, freight and goods movement, and national defense transport and is part of the Pacific Coast Bicycle Route. Through the project area, US 101 is a four lane freeway with 12-foot through lanes, 5-foot inside shoulder, 10-foot outside shoulder and approximately 27-foot median. Right -of -Way width varies, but is generally 177 feet. The nearest interchanges on either side of the project study area include Los Osos Valley Road located at PM 25.9 and Madonna Road located at PM 27.5. There is an existing northbound US 101 off -ramp to Prado Road and an existing Prado Road northbound on -ramp to US 101. The ramp connections to Prado Road are located at PM 26.8. Prado Road, classified as a minor arterial according to the Caltrans California Road System (CRS) maps, is currently a two-lane facility that spans roughly one mile from its intersection with US 101. The area surrounding the project includes commercial uses northwest of the intersection of Prado Road and U.S. 101, commercial and residential uses northeast of said intersection. Several key public service and transportation -related facilities are located along the Prado Road corridor and are relevant to the proposed project. These include the City's Water Resource Recovery Facility (W RRF), the 40 Prado Homeless Services Center, and the adjacent 46 Prado site. In addition, a nearby transit operations facility serving local and regional bus services contributes to transit -related vehicle movements in the area. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-4 Page 605 of 1059 DRAFT The San Luis Ranch property is currently in the initial phases of development, with approved commercial, residential, recreational, and agricultural land uses under the San Luis Ranch Specific Plan, adopted by the City in 2017. There is a roundabout within this development at the intersection of Froom Ranch Way and Dalidio Drive that was constructed with the ability to incorporate an intersection with the future extension of Prado Road to the west US 101. The project also includes realignment of the Elks Lane intersection to accommodate the footprint of the proposed interchange improvements. The existing Elks Lane connection to Prado Road would be removed due to its conflict with the planned U.S. 101 northbound on- and off -ramp terminal intersection at Prado Road. To maintain local access and circulation, Elks Lane would be realigned to intersect Prado Road east of its current location, adjacent to the 40 Prado Homeless Services Center. On the eastern end of the Prado Road alignment the project abuts the western limits of the San Luis Obispo Creek Bridge Widening Project, which has independent utility from the proposed project and is currently being reviewed by the City of San Luis Obispo. This project includes widening the existing 2-lane bridge to provide a total of six lanes and a sidewalk on each side of the bridge. 1.6 Funding It has been determined thatthis project is eligible for Federal -aid funding. The City plans to fund the project with a combination of impact fees, debt financing, and the SLOCOG Regional Transportation Improvement Program (RTIP). The PA&ED, PS&E, and Right -of -Way support phases are programmed with 100% local funds. The Construction phase has nearly $64 million currently programmed from a combination of RTIP and local funding sources. The City will continue to pursue additional funds through other state and federal grants. 1.7 Impacts to Traffic It will need to be determined whether the current ramp configuration at Prado Road will remain open during construction, and if they can be used for the northbound detour. Southbound closure will be more complicated, possibly requiring use of a median crossover, or detourvia Madonna Road and Los Osos Valley Road. Mainline closures of US 101 should not be required for construction of the retaining . A detour for Elks Lane will also need to be implemented during construction. A preliminary Transportation Management Plan (TMP) Data Sheet/Checklist was previously prepared for this project and was included in the Project Report. 1.8 Staging and Contractor access Access to the site is not anticipated to be limited due to its proximity to US 101 within San Luis Obispo. Construction staging areas are anticipated to be located within the closed portion of Prado Road to the east of US 101 and the undeveloped area to the west of US 101. 1.9 Right of Way An encroachment permit from Caltrans will need to be obtained for portions of the western overcrossing constructed within Caltrans right-of-way. Right-of-way acquisition will be required for portions of the western overcrossing to the west of US 101. Temporary construction easements may be required to establish sufficient area for construction staging areas. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-v Page 606 of 1059 DRAFT 1.10 Hydraulic Considerations The project is within the limits of the floodplain of San Luis Obispo Creek. Accordingly, HDR, Inc. (HDR) has provided a Preliminary Bridge Design Hydraulic Study (BDHS) for this project, and is included in Appendix F. The Preliminary BDHS includes: ➢ A review of available hydrologic data ➢ Hydrologic analyses ➢ Hydraulic analyses to determine design water surface elevations and flow velocities for existing and proposed conditions ➢ Scour analyses to estimate potential scour depths for the proposed condition 1.10.1 Floodplain All structures are located within the San Luis Obispo Creek Splitflow floodplain, which is categorized as a Zone AE Regulatory Floodway based on FEMA Flood Maps. The layout of the structures for this project was partly governed by the need to satisfy both FEMA and City requirements for allowable rises in water surface elevation in the floodplain between existing and proposed conditions. The analysis included in the Preliminary BDHS indicates that the proposed condition for this project results in a maximum change in water surface elevation of only 0.3 feet. 1.10.2 Scour In accordance with Caltrans STP 2.6, the bridge design will consider scour for the 100-year flood event (Scour Design Flood) along with scour for the 200-year flood event (Scour Check Flood) for the Extreme II limit state. The bottom of the pile caps for the abutments will be located below the total scour elevation for the Scour Design Flood with the exception of abutments supported by the MSEA Type II wall (retaining wall 9). Retaining Walls 1-8 will have the bottom of leveling pad at the same elevation as bottom of footing directly adjacent to the abutments then step up incrementally to maintain a minimum embedment of two feet for the remainder of the wall length. Retaining Wall 9, as it is supporting the remaining bridge abutments, will have its bottom of leveling pad placed below the total scour elevation for the scour design flood. In accordance with guidance provided by Tony Nedwick with Caltrans Structures Hydraulics, the pile caps for the abutments at the MSEA Type II wall do not need to be located below the total scour elevation of the Scour Design Flood as long as the abutment piles are designed to be stable under scoured conditions while neglecting any support of the MSEA Type II wall. The piles for the four abutments located at the MSEA Type II wall will be designed accordingly. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-6 Page 607 of 1059 DRAFT Scour Depths are provided from HDR and are as follows: Table 1-1 1 100 Year Flood Scour Values Retaining Degradation DepthContraction Wall No. Scour Depth Depth Prado West Overcrossing Abut 1 1&2 NA 1.7 6.2 7.9 Prado East Overcrossing Abut 3 3&4 NA 0.7 1.6 2.3 US 101 NB Off -Ramp Abut 1 5 & 6 NA 1.1 4.8 5.9 US 101 NB On -Ramp Abut 3 7 & 8 NA 1.2 1.4 2.6 Prado West overcrossing Abut 4 (controlling side) MSE NA 1.2 1.7 2.9 Island Table 1-2 1 200 Year Flood Scour Values Retaining Degradation Contraction Short Term (Local) Total Scour Dep Wall No. Scour Depth Depth Prado West Overcrossing Abut 1 1 & 2 NA 2.1 7.8 9.9 Prado East Overcrossing Abut 3 3&4 NA 1.0 2.9 3.9 US 101 NB Off -Ramp Abut 1 5&6 NA 1.3 5.8 7.1 US 101 NB On -Ramp Abut 3 7 & 8 NA 1.3 7.7 4 Prado West overcrossing Abut 4 MSE NA Island 1.2 2.8 4.0 1.10.3 Drainage Due to the high potential for flooding, retaining wall designs must take into account the high likelihood that a portion of the wall could be submerged. Drainage behind the wall facing in the form of gravel backfilled underdrains will be provided to reduce hydrostatic pressure behind the walls. 1.11 Geotechnical Considerations Yeh and Associates, Inc. (Yeh) has prepared a Draft Structure Preliminary Geotechnical Report (SPGR) for the bridge structures and approach retaining walls included in this project and is included in Appendix G. The Draft SPGR includes a discussion of project alternatives, site conditions, geologic conditions, seismicity and faulting, geotechnical considerations regarding the overcrossing and ramp structure approach D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-vii Page 608 of 1059 DRAFT retaining wall alternatives, and additional field and laboratory data needed for design. The preliminary characterization of the subsurface conditions is based on boring information from previous explorations performed in the vicinity of the project site as well as cone penetration test (CPT) soundings performed for Phase 1 of this project. The Draft SPGR identifies Mechanically Stabilized Embankment (MSE) walls as generally the most suitable Earth Retaining System (ERS) for all of the structure approaches and the Island at the structure intersection. The MSE walls would be non-standard MSE designs based on the foundation conditions and would need to consider the potential for scour from flooding. As an alternative, modified conventional retaining walls supported on deep CIDH piles are Considered Suitable. The CIDH piles are recommended to be embedded below the compressible and liquefiable (if present) layers and bearing within the Francisan melange bedrock. The bedrock is located approximately 60 feet below the ground surface based on the available data. 1.12 Seismic Ground Motion The seismic data for the project was generated by Yeh using selected site parameters and ARS Online version 4.0 to estimate ground motion parameters in accordance with Appendix B of the Caltrans Seismic Design Criteria (SDC) version 2.1, dated January 2025. Seismic data was generated for the Safety Evaluation Earthquake, which is defined as an earthquake with a 975-year return period. The shear wave velocity for the project site was estimated from the CPT data obtained by Yeh at the project site. The preliminary design response spectrum for the project is provided in Figure 1-2 below. For additional information, see the Draft SPGR prepared by Yeh included in Appendix G. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-8 Page 609 of 1059 DRAFT C.L 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Period, T (sec) — -Design Response Spectrum AIRS Online: Mean Magnitude: Spectral Damping: O Peak Ground Accleration = 0.39g Latitude: Longitude: VS30: 8.0 9.0 10.0 V4.0 7.05 at 25.37 km 5 percent 35.2569 degrees -120.6748 degrees 320 meters/second 1.13 Liquefaction and Lateral Spreading Potential Based on CPT soundings, potentially liquefiable medium dense layers of sand were encountered at depths of 44 to 55 feet below the ground surface. Liquefiable materials are not likely to impact roadways or surface improvements but could have an impact on deep foundations for the project. Additional subsurface explorations will be required to verify if there are liquefiable layers and if it will be a design constraint. Liquefaction -induced lateral spreading is not a consideration for the design of the retaining wall structures based on review of previous data collected at the site and the CPT soundings performed for this project. 1.14 Structure Layout The alignments of the Prado Road overcrossing as well as the US 101 Northbound on -ramp and off -ramp structures intersect directly adjacent to US 101 on its east side. Previous studies of the floodplain for this project had determined that the overcrossing would have needed to span approximately 1050 feet between the west and east approaches in order to limit water surface elevation impacts to an acceptable amount. This would have required the ends of the on -ramp and off -ramp superstructures to directly connect to a span of the overcrossing, which would lead to nonstandard detailing and construction methods, more unpredictable seismic performance, and increases in construction cost. The Consor team has since performed more detailed hydrologic and hydraulic analyses of the floodplain to aid in the preparation of the Preliminary BDHS. Iterations of these analyses were performed to determine the most cost-efficient structure layout that still meets the requirements for impacts to the floodplain. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-ix Page 610 of 1059 DRAFT It was determined that reducing the total length of the overcrossing to 750 feet would be acceptable through these iterations of the analyses. This led to converting the easternmost span of the overcrossing to a bridge approach supported by MSE walls, and more notably implementing an "island" of MSE wall at the structure intersection directly east of US 101. Further discussion of the island support is included in Chapter 3 of this Memo. 1.15 Design Exceptions No design exceptions related to the retaining walls are currently anticipated for this project 1.16 Retaining Wall Design Criteria The design criteria for the retaining wall structures are primarily based on the codes and guidelines below. ➢ Road Design Roadway design will be based on AASHTO "Guidelines for Geometric Design of Low -Volume Roads 2019 (2nd Edition)" (GDLVR) supplemented with AASHTO "A Policy on Geometric Design of Highways and Streets 2018 (7th Edition)" (Green Book), and County Public Improvement Standards 2022 where applicable. ➢ Retaining Wall Design Bridge design will be performed in accordance with "AASHTO LRFD Bridge Design Specifications (8th Edition)", and the "Caltrans Amendments (dated April 2019)". The latest versions of the Caltrans bridge design manuals, Bridge Design Memos (BDMs), and Structure Technical Policies (STPs) at the time of type selection will also be utilized in the design. ➢ Seismic Design Seismic design will be performed in accordance with the Caltrans "Seismic Design Criteria Version 2.1 (February 2025)" and the latest information available from Caltrans Earthquake Research. ➢ Hydraulic Design The hydraulics design will be in accordance with Caltrans STP 2.6 "Hydraulic Design for Structures over Waterways". The proposed bridge soffit will be located a minimum of 2 feet above the 50-year flood elevation, or convey the 100-year flood (i.e., no freeboard), whichever is greater. 1.16.1 Corrosion The Draft SPGR indicates that the soils at the site are not corrosive. Standard concrete cover and conventional uncoated reinforcement details will be used for the design. If metallic tensile reinforcement for MSE walls is used, special consideration of the corrosion potential will guide the selection of backfill material requirements. Freeze thaw is not a concern at this site. 1.17 Utilities Various utilities located within the vicinity of the project site will either be relocated or remain in place during construction. Among these utilities is an oil line owned by Phillips 66, which will be relocated with sufficient clearance away from the US 101 NB Off -Ramp and Prado Road Eastern Overcrossing foundations. It is anticipated that the only utilities that will be carried on the bridge will be smaller dry utilities (6 inch diameter maximum) located within the sidewalks on the overcrossings. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-10 Page 611 of 1059 DRAFT 1.18 Environmental Studies and Permits SWCA, Inc. will conduct and prepare the technical studies, prepare the California Environmental Quality Act (CEQA) document, and prepare project permit applications. The County will be the lead agency for CEQA, and the anticipated document will be an Initial Study Mitigated Negative Declaration (IS/MND). Caltrans will be the lead agency for the National Environmental Policy Act (NEPA), and the anticipated document will be a Categorical Exclusion (CE). The project is not expected to result in any negative impacts to native plant or animal species. SWCA will prepare permit applications after environmental clearance is obtained shown below. Note the City will be responsible for obtaining an encroachment permit from Caltrans for all work within Caltrans right-of-way. Table 1-3 1 Permits Regional Water Quality Control Board (RWQCB) Clean Water Act (CWA) § 401 California Department of Fish and Wildlife (CDFW) Streambed Alteration Agreement 1600 D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 1-xi Page 612 of 1059 DRAFT CHAPTER 2 APPROACH RETAINING WALLS 2.1 Preferred Structure Type Summary Wall No. 1 Station Line "P" Beg Sta 44+68.5 End Sta 46+16.59 Max Height (ft) 26 Length (ft) 142 Area (ft 2) 2783 Recommended Retaining Wall System MSE 2 "P" 44+63.99 46+17.48 26 162 3095 MSE 3 "P" 55+02.25 57+76.99 16 275 2856 MSE 4 "P" 55+02.25 57+41.00 19 239 3162 MSE 5 "F" 70+75.18 74+71.18 23 396 5541 MSE 6 "F" 70+74.78 74+71.18 22 397 6283 MSE 7 "N" 33+23.03 36+22.34 24 299 5023 MSE 8 "N" 33+22.86 78+00.02 26 1,768 26280 MSE 2.2 Structure Type Alternatives 2.2.1 Mechanically Stabilized Embankment (Preferred) MSE walls are common fill type walls that consist of tensile reinforcement within soil backfill. MSE walls proposed for this project would include a precast concrete facing, Barrier slab and Concrete bridge barrier. The tensile reinforcement layers can be either metal or geosynthetic. The Benefits of using MSE Walls at this site include: • MSE walls can be designed to tolerate significant settlement that may be associated with the consolidation of the native alluvial soil and liquefaction related settlement. • Lightweight fill may be used as partial or full backfill material in the MSE to further reduce the potential settlement and decrease foundation bearing pressures. • MSE facing units can easily be customized to match the corridors aesthetic goals. • Reduced construction costs compared to conventional retaining walls The native clay soils in the project areas make settlement a high priority for the design of all the retaining walls. Overturning failures from rotational stresses and settlement are the most typical cause of MSE wall failures. The wall designs will carefully consider the stability of the whole MSE system to prevent a similar failure mechanism. 2.2.2 Conventional Retaining walls Conventional Retaining walls like Caltrans standard plan Type 1 Retaining walls are also common fill type walls that are typically cast in place, cantilever, reinforced concrete walls. For this site, it is recommended to modify the conventional retaining walls to support deep foundations on either driven piles or CIDH piles. An existing conventional retaining wall near the overcrossing structure at Los Osos Valley Road is supported on deep foundations that bear in similar materials to what is found at the Prado Road Interchange. The benefits of using conventional retaining walls with deep foundations include: D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 2-12 Page 613 of 1059 DRAFT • Straightforward design and construction using Caltrans standard plans as a basis. • Deep foundations can be designed to bear in the underlying older alluvium or bedrock and potentially provide resistance to scour, settlement and liquefaction related effects. Cost for conventional retaining walls are typically low when compared to other structural retaining wall types like soldier pile walls, however with the soil conditions requiring modifications for deep pile foundations, this alternative looses its cost effectiveness. 2.3 Constructability Construction sequencing is an important consideration for MSE walls adjacent to bridge abutments because the wall, approach embankment, and bridge components are often constructed in stages and require close coordination between contractors. Delays or changes in the sequence can affect access for earthwork operations, compaction efforts, and bridge construction activities. Care will be taken to ensure that the reinforced fill is placed and compacted in accordance with the wall design while maintaining adequate access for abutment and bridge construction. Construction staging will have to account for any temporary excavation or equipment access requirements that could impact the stability or integrity of the developing wall system. Temporary surcharge loads from construction equipment are another key constructability concern. Cranes, material stockpiles, haul trucks, and other heavy equipment operating near the wall can impose loads that exceed those assumed in the permanent design. These temporary loads can increase lateral pressures within the reinforced soil mass and may affect wall performance during construction. 2.4 Barriers The walls along Prado Road (Walls 1-4) will have barrier slabs supporting Caltrans Standard Plan Type 732SW concrete barriers. The Type 732SW barrier on the north side (left edge of deck) will provide a 6- foot wide sidewalk, which is in conformance with the minimum width provide in the standard plan. The Type 732SW barrier on the south side (right edge of deck) will provide a total 14-foot wide sidewalk to incorporate a Class I Bikeway in accordance with the Caltrans HDM The walls on the US 101 NB On -Ramp and Off -Ramps (Walls 5-8) will have barrier slabs supporting Caltrans standard plan Type 836 Concrete Barriers. All walls will have Tubular Handrailing in addition to their respective concrete barriers. 2.5 Aesthetics Aesthetics are proposed for the MSE approach retaining walls. Architectural surface treatments will be incorporated in the precast facing units. Final Surface treatments will be coordinated with the city during final design to ensure consistency with the corridor aesthetic goals. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 2-xiii Page 614 of 1059 DRAFT 2.6 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25 contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for total structure cost both alternatives is shown below: 1 $1,646,000 .- $2,720,000 2 $1,939,000 $3,058,000 3 $2,194,000 $2,433,000 4 $2,326,000 $2,797,000 5 $3,626,000 $4,674,000 6 $3,944,000 $5,340,000 7 $3,136,000 $4,744,000 8 $16,642,000 $23,625,000 Total $35,453,000 $49,391,000 2.7 Recommendation Alternative 1— Mechanically Stabilized Embankment is the preferred alternative because it provides a the most cost-effective solution for this site while also prioritizing ease of design, constructability, and performance. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 2-14 Page 615 of 1059 DRAFT CHAPTER 3 RETAINING WALL ISLAND 3.1 Structure Layout The proposed island support will be composed of Two tiers of MSE walls. The lower level will be Mechanically Stabilized Embankment Abutment (MSEA) Type 2 (per Caltrans Memos to Designers 5-1) that spans the entire perimeter of this intersection and is offset to provide a minimum clearance between the front of the MSE wall and the abutment of each of the four structures. A second tier of MSE retaining walls will act as extensions and transitions between the Abutment wingwalls at each corner. These walls will be consistently offset behind the first tier to match the abutment layouts. These walls are not positively connected to the bridge abutments and do not contribute to or rely on the stability of the bridge. Figure 3-1 1 MSEA Type 2 Diagram (MTD 5-1) The implementation of the MSE island splits the overcrossing into two separate structures, western and eastern, and provides cost savings and more predictable seismic performance compared to the previously proposed elevated intersection. The cost savings are primarily associated with the reduction in retained height of the abutments, reducing vertical and overturning loads on the deep foundations. 3.2 Preferred Structure Type Summary The summary below breaks down the individual segments of the lower level of the Retaining Wall Island. The segments are separated by angle points and the structure noted in the table identifies what bridge's abutment is founded directly behind the segment. The recommended structure type for the whole system is an MSE/MSEA. Wall Structure Segment 1 2 Prado West Overcrossing Average Height 22.1 Length (ft) 60 Area (ft2) 1322 2172 22.1 98 3 20.9 52 1076 4 us 101 Off -Ramp 19.7 50 974 5 19.7 67 1320 6 Prado East Overcrossing 19.7 91 1796 7 20.9 53 1113 8 us 101 On -Ramp 22.1 76 1684 D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 3-xv Page 616 of 1059 DRAFT 3.3 Structure Type Alternatives 3.3.1 Mechanically Stabilized Embankment (Preferred) MSE walls are common fill type walls that consist of tensile reinforcement within soil backfill. MSE walls proposed for this project would include a precast concrete facing, Barrier slab and Concrete bridge barrier. The tensile reinforcement layers can be either metal or geosynthetic. The Benefits of using MSE Walls at this site include: • MSE walls can be designed to tolerate significant settlement that may be associated with the consolidation of the native alluvial soil and liquefaction related settlement. • Lightweight fill may be used as partial or full backfill material in the MSE to further reduce the potential settlement and decrease foundation bearing pressures. • MSE facing units can easily be customized to match the corridors aesthetic goals. • Reduced construction costs compared to conventional retaining walls The native clay soils in the project areas make settlement a high priority for the design of all the retaining walls. Overturning failures from rotational stresses and settlement are the most typical cause of MSE wall failures. The wall designs will carefully consider the stability of the whole MSE system to prevent a similar failure mechanism. 3.3.2 Conventional Retaining walls Conventional Retaining walls like Caltrans standard plan Type 1 Retaining walls are also common fill type walls that are typically cast in place, cantilever, reinforced concrete walls. For this site, it is recommended to modify the conventional retaining walls to support deep foundations on either driven piles or CIDH piles. An existing conventional retaining wall near the overcrossing structure at Los Osos Valley Road is supported on deep foundations that bear in similar materials to what is found at the Prado Road Interchange. The benefits of using conventional retaining walls with deep foundations include: • Straightforward design and construction using Caltrans standard plans as a basis. • Deep foundations can be designed to bear in the underlying older alluvium or bedrock and potentially provide resistance to scour, settlement and liquefaction related effects. Cost for conventional retaining walls are typically low when compared to other structural retaining wall types like soldier pile walls, however with the soil conditions requiring modifications for deep pile foundations, this alternative looses its cost effectiveness. 3.4 Constructability 3.4.1 Obstructions to MSE Reinforcement The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the piles are not isolated from the MSE wall and are supported laterally. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 3-16 Page 617 of 1059 DRAFT Section 5.4.2 of the FHWA GEC 011 discusses Methodology for designing and installing the MSE wall reinforcement around vertical obstructions like piles or horizontal obstructions like culverts . FHWA stresses the importance of not leaving any reinforcement unconnected to the wall facing by arbitrarily cutting or bending reinforcement in the field. They provide recommendations of alternatives like locating obstructions between reinforcement, shifting or splaying reinforcement around the obstruction, or designing a structural frame around the obstruction that is capable of carrying the load from the reinforcement back to the front facing. 3.5 Barriers The Island will have two tiers of MSE Walls. The lower tier protecting the abutments and fill will have a wall cap beam and embedded cable railing for fall protection. The upper walls of MSE, acting as extensions of wingwalls between the bridge abutments, will have a barrier slab supporting a Caltrans Standard Plan Type 836 Concrete Barrier. 3.6 Aesthetics The MSE island presents a large canvas directly adjacent to US 101 for aesthetic touches to be added to the corridor. Two of the four segments between abutments are directly visible to drivers on US 101. Ideas currently being considered for these areas are tiered planter boxes, Architectural treatment on wall faces, and Large letters spelling out "San Luis Obispo". Final aesthetic treatments will be coordinated with the City during final design to ensure consistency with the corridor aesthetic goals. 3.7 Cost Estimate General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25 contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for total structure cost of both alternatives is shown below: Wall Alt 1 MSE Alt 2 Caltrans Type 1 No. • $6,908,000 $12,660,000 3.8 Recommendation Alternative 1— Mechanically Stabilized Embankment is the preferred alternative because it provides a the most cost-effective solution for this site while also prioritizing ease of design, constructability, and performance. D218721CA.00 • April 2026 • Prado Road Interchange • City of San Luis Obispo Retaining Wall Type Selection Report • Page 3-xvii Page 618 of 1059 DRAFT APPENDIX A: Retaining Wall 35% Plans n, consor Page 619 of 1059 4 4 4 o ono o 44*42.9g RC O� - � o 0 0 �N U A W ) u1 A � v � ooIT Q N O A I 0 � O Ic 0IT I v o < Z A ? IT A w li i1Q A z " p -- - _ — m om m w\ A�Np C) IT T p � A tnN y z o m x m C _ (S O DA O ;a O i , m O a N nC yo z m i 'y ED ry A O CO J< o X X 1. z O 1 .7 ° O . p0 iZ N ?� D O c m D m ao n z o G) p ° D z D 0 z Jr r z �o Z m n o A yo n o 3 � ro z z 3o O G� < _ o y; m c \ V m \ m �m A J \ D < N - J A z0 z0 p A � O A r A p N A - � J W w o m o D D z tO Max Wall Design Height = 22'-4" J W n - o II 39 1 0 v o m mF i _ °,r m om Min I IIIIIII I I I I I I I a� f o �I IIIIIIII IIIIIIII I I I I I II A I o a 0 I =O I E s I I I I I I S o O MR, o m� N logy m m W U I I I I I I w p — --r----T------- 9�m0 i fn AC OE - o r I o N m 3 a� r sgem N O 3 - O 059 USERNAME Neh,H.—n DAIS PLOTTED 7/1/=0 6:36:08 PM 11.E PLOTTED 6:36:08 PM (& / \ }� /� {{ , \ ) ^ --r-- -- -------- � \$l�IIIIIIIII - %k�lllllllll 6 �IIIIIIIII z \ o Max » __ Height_ 2 \` DAM PLOTMD x ,w, . _ e_,a, PM �} (! - _ rZ )@ : c � r( °, _ / §r w \ 3 / \ ,} / : ~,`1`\1059 /! ,/ | � - 0 ) \(\ \/\o o \ ; : -jl _ \ : _ i - 0 , PT;2 _> ; \ ` f: � x � \ } ( }( � :)) \So / \ ; DL \ � <� M. - > - \( 0 r= � \9% } ) §t) z z \ \�m �\ Mc \DO ( | m;/■ | ` . � \ j k : \ r z = M J) »p= § 4\ ! ` f j R, { / § lu § �: � / |% CJ > 2 §# / / \\§) , 1059 A /}/ ! yyy � \(,So � -1§ !ez a r !£ k ,;r \J!2 �\\\ )�! - ` 0 §\)o \B ■ (| >§ }\ j k \}\ z0 o o / \ \_ < 2 Em o \ \ ( ) , z _\ , \� / \ \\ \ )! \ ^\ p. { } \ \ \ \m - 0 �� / ƒ¥ _ate _.DAM PLOTMD x ,,. . *7 � s§ \\ 6 z ONO ,no rdbm � } � 1n IN r - � v ) s §r . / > ,} / ! . \)f / ; \) ( ) » 059 IA v u DAIS PLOTTED 7/1/2026 6:38:22 PM p 0 10 o "H" Design Height m Jm 3 1w° p Ni o p F p 3m oo � m 3 Min i � - m 3 a n O N O I W r--r- ° I I I I a n I I I I I aA F W I 2-0 _ Min m Duo O - W m ? p 3 m m N F o o - m ut II W Max Wall Design Height = 13"-0" J N N � NW 059 m p3N o I I o + j I zm mop I I N m Z_ ^Z O r 0 J z i Z z O m U D cz m Im I � oo oo V o ] (n A2 I � r Z W _ D O o Z n I I � z �1 w N A N n � N 0 0 0 1. w N z MATCHLINE STA 72+75.00 SEE SHEET 7 of 0 II N� m n O y N m i D n z_ _ z O N on 4 N D -0 z f. D z N O s2 D o A m ` o ,',o D Dn z � . z �p 30 z U DAIS PLOTTED 7/1/2026 6:39:09 PM TIME PLOTTED 6:39:09 PM MATCH LINE STA 72+75.00 SEE SHEET 7 of z U I r �a2y �Aa p v Aq o C) O 2 �2T - V1 m W N s�eR = i - p 5�•a Vs f w A a 059 _\ \ I » > / z 0 q 2 0 }$\ 0 \\/ ! f j « § 0 \ z j M DAM PLOTMD x 6:_12 PM MATCH LINE SA72+ Rm SEE+Elem MATC m« STA 72+75.00 SEE SHEET ey -IV 059 \z \ §; }\ x \\ \ \\ ) _§ q 7 & }k\ / z z 2 0 0 / � `7 ? 1z \ - _ \! 0 0)>`30 z ) _ o > ; cz % m ( .; MATCH LINE 7A72+@ «E+EIx@ m m 0 }§ 4p \ 0 z MATCH LINE STA 72+72.00 £EmEEIx@ r)@ - c \) r -a ° §: \/ _ 2 §r . / > zo ( ) : 059 _ate _.DAM PLOTMD x ,_, . ; \z \ §; � TCH LINE STA 72+75.00 SEE+ETxa MATCHLINESTA72+75.00 SEEmEEI*m -IV 059 7 w Design « /{ \ m $! =2 --Ii }J \ ( } _ $ m Q /© _ _ _ : p ;IIIIIIIII -o =;�IIIIIIII — — \{ ;IIIIIIIII Cn ^� �;I�IIIIIII - � \ � �--,-- -- - -- ----- k o (! 2! j z 2 \ : 2\ ±\ § / / a - ` ` 2 7 ` » zr-- -- --- -------- , = , 5 =�IIIIIIIIIo \ /\§�IIIIIIIII »�IIIIIIIII ._ �IIIIIIIII - ) o � § o � . r Min § \ (} o ` - z{ v Design Height Do DAM PLOTMD x ,r, . rZ - )@ c , r -a ° §: )� \ {` ) s / §r . 059 4 q nTo q N Z P y o � _ a - _ _ N j7, �Do� � N 4 Obi------- o _ NQ O : 0 �. �O j - '�' �' I �•� / I j mQ � f - < w A ��o �" �_ a y r N Z o 0 W W A O I O ZO T= ti K I C ym I � D � I I I l I I Ilw I I A I I I � � D I I l �n D z I II II �I p O I N I - ' I I s O gg m .... ^ f G v m I n o Z d Q � o 4 � I F, TO I v ynA III EC m m 0 0 -� _ v 4+90.43 m A �_ z cn m ul O 2-1 m� o mM III z zZ rn — I Ili III a I\ w I I I m NI I i o I � I I A O O ti III III A I F Ilm it I 'I i m I I O X R I p Z/`III I W wl il D I I �� �� Z `-' I I ► gn�n S - w 0 QDr I mA mA�mW 5 '^��� 0n=n Q mJA <I 0C i O on NJ<r I Z om W 1L Z ~OrRR OR 00 o p� Qm J n m N np, y No o o N on O c m A J o a s�eR a Wy � 1059 J-14 t Aeniey.nanson DAIS PLOTTED 7/1/2026 6:41:09 PM IIML —11— n. —1 rM o \ \\} \a =42� � - - - - -- ` |§!° ----j \ \\ \\ \ ■ \ � m�/■ �� \ .. aEaaTx¥ ��"^®�^� DAM PLOTMD x a „ r mR 7A e «E+EEIxy -IV j 059 (§ § \( r mR SAS m SEE+Elxa \(� � I E So I � - \ §§|§l \ z § = 4 ` , . \ \�[ § } �5 /C. \ . �/- � ,®j " .. � }\ \k 0 IIXXXA� \� \( 5. 7 Arm £ 7A m £}+EI\@ $ ¥ _ / z 2 / 0 q }$\ 0 \! j 0 _ § | 0 \ z M j MArHuNE7A m «E+Elxy § ] > n } o o = \ I o o ol o _ - ` o I g3HLIE eke @ sE+alx@ j 059 4 4 4 o n�o 5 a o o " MATCHLINE STA 38+00 SEE SHEET X of MATCHLINE STA 38+00 SEE SHEET X of 0 � o � � I W -• to I = e I o I D t F s I I I I I o = I N _ moo I rT o a o £ G - Ii I II I � F ➢ I N I TS o n 0 I I N O I I 3 a � 3 v So I m n I W I II < m \p I I m I I I H � a yF I I 66 I I I W W I I m O Io a � c m o �m o A Bg $ m II r o m = A o �z ri D o r - 08 ; Z a K Z 00 D w o ro Y ca- p10 N x - _ F W I m o C7 J o J F, O p 3 m T p n A I 39+66.77 BC � y z o i m c C. �o� z Cn m n I � K C> I I t� o yz m 00 z Z A J N p I N i W U o nl I r*1 A Q ~ llxxxA� O ..D `` _: z �� m p+ =N � O A I W O II III II m p > s D Zmj MATCHLINE STA 40+50 SEE SHEET X of MATCHLINE STA 40+50 SEE SHEET X of 'yy/ d£ 'n �7 A � � o o N Z �Z (A� c uv o O m Q p03 00 n �g = iy D NoIc o r m> 0 Z M O do � 9 a� V s - ff w Ao A ;1059 USERNAME Aeh,H.-- DAIS PLOTTED 7/1/2026 6:41:56 PM 11.E PLOTTED 6:41:56 PM r mR SAa m SEE+Elxa mHuNEeAa m SEE+Elxy \}� : RIZo o - �� (o I OF $ I \ \ !) - o iD \�\ m SO ` \) _ So I w :m � - - !» \ z : { ( - k , (/!] . \ � ^ F,S2! } m \e% (\} � I I / _ I !/- § - _ I _ \k � ` vo / lu:6§ E lxeAr 6 A�& mR 7A am +ramlx@ _\ » \ » � ( |/ (- }% Q)@ / ;! r\ : , / §/ :a \!z � o ® m o {` §7 :§ ° § , 2 /Hc \ , \ §# z \ / \ > ,} / � \ /!`\1059 _ate _.DAM PLOTMD x a„ _ PLOTMD 6:�1;58. 4 4 4 o n�o � m - a � o MATCHLINE STA 70+00 Obi SEE SHEET X of � ao �3N clw j 0, A N y K po O] rn I 2 2 B K � I I I I :6 4 C J co m K r I� I QI A m W i _ ;owNo �r €= o A Y1YwJ N m � I ' c> I I m � v o O m v pnA z o I m c_ � O ao I z Cn m C> y O oc I ,Z o 0 _ � n - J N I i y N X m I j ryt X m A I m D m MATCHLINE STA 72+50 SEE SHEET X of 2 O �7 = a o o 1 r z Z O m 0 r n 2 � � D o m DAIS PLOTTED 7/1/2026 6:42:01 PM MATCHLINE STA 70+00 SEE SHEET X of II I m p I I I V= Ui � o JO 1 O } 3 m II N o I I I I I I I I I N o a o J ) I I I I I I I O m l I � I II � DI o I � 3 _ I o II I 8- 3 o I I II I J N � t1 o � � I I I I I I i o N m � o m III II ilyll m�tn � a o � J O N Z A 1! I MATCHLINE STA 72+50 SEE SHEET X of -Nq 9 t 059 /� ; / A3HE» ea�2 @ SEE SHEET x* Fa \ -o}o \ \ §; \ L »mom E£k� @ SEE+Elx@ DAM PLOTMD x ,ra . MArHuNE7w72+ @ «E+Elxy ; ) } ]o , ! } _ } o G ] � T. DTI o o _ ol _ ^ . r mR Sam m SEE SHEET xe 4 »g;« n �-N\ ate) 9, \ /\ y |/ 059 !) _( ASmR oo SAS E SEE HETx¥ TCHuNE ewe m SEE+Elxy ) ,\ \}3 - : ` 3 D. - \ \\ � _ .3 \ ; ,\ I _!§ I z. 76+06.06EC / } , \ ( _ ° vL § 2 |( 2 m ,;{ «z ` m \ J ® 2 } \ $ §« _ , g \ _ e 77 ^ { \7o : /\! - ;9g §t) § z . } \ \CS , \§z` \ § \/ I : I I § m / = 5) v. § / _ n \f )@ p \) :a ri : P / : Do EU ! 2o 0 p j ) _ {` § : § _ _ , / |� ? , ` \ / ° \ G - zo\ Io 1059 2 v Design Height ({ \ _ § }( » ! ; _ §\ .0" _ : / �IIIIIIIII - �'Illllllll — — // {'Illllllll ,-4 ') �'Illllllll 'I IIIIIII/ ) ;cm \ 4- / — — -- --- � � o f! 2! _ §o z ; \ f $\ 2\ f , - 2 \ � -- --- -�------- , 0 r-- } / } \ l�IIII�IIII :,IIIIIIIII /{ `�IIIIIIIII _Iq ,_ -� �IIIIIIIII - � o. 2 /2 2'-0 �. Min § / (\ \o } \ - z } v __ «° )` ƒo DAM PLOTMD x 6:r18 PM 059 m A m N - - Z O o D O N 3 y � N O a F. � Ho 6j °O=n P" 50+65.25 AP ° ao Elev 151.10 F A W ° I I S O OW ° O m m= o � I - II o \" ° "P" 50+65.25 AP O Elev 151.10 (n W I UI N V 3 "P" 51+04.49 AP �.. Elev 148.67 � - m _ [—P- 51+54.18 AP rn Elev 148.67 ti = V m r "P" 52+08.60 AP _ So I, Elev 148.67 a m A v I I � , m r mo D - G7 , Elev 151.1 O I � I z VI Vl Z Vf ' O ? N Z m a N O a O O _b O m f i F D 0 O' O O Z V D N N rn O D I 5' 3 m N O 1D 00 V m (P N ol 3 n O I n O J I �o °- G N o C W m G O V D o o a'S o In N W W D s l��------�-M4 I IIF� o N D Z m v III I I I I`�-JI ff N V N ti p"!� 'O'R p ; o �n m� W y r > - Oo Z. ao cis O r J rn � 99 C S1t.Rf i a - AO �� � pp rJ V s O Max Wall Deszo ign = Height = 18'-6Y" , «a , DAIS PLOTTED 7/1/2026 6:42:21 PM 11ME PLOTTED 6:42:21 PM 059 z_ 7 08 2 0z z� fA m D o o z A g a 5 g W 0 o 0 N MATCHLINE STA 12+75 rn J I W � o o o y ° + o o 3 it 0- D x p P — 0 ° 3 0— a - 0 z p 3 N m m 3.0 - a m a ' n ° � a p T po m 3 3 D z _ � a='s �, N A 4,Ap W N O NSF < p m W m p o 01 i o r rnn 2 moIC a R �o m � ° = n x m . 1 I 1 1 I 1 a °,, f n m A 1O "P" 52+08.60 AP 1 1 1 1 1 I 1 1 I I 1 1 I 1 1 4111 1 1 o o o + = o z P n A _ � "P" 50+65.25 AP Elev 151.10 1 I I I 1 1 1 LI I I "P" 50+65.25 AP o 0� G m D" < K 1 1 1 1 1 1 I Elev 148.67FTTT I j I I I I I I I I I 1 1 I I I I I I 1 I v I "P" 52+08.36 AP TITT < m v6 - m 0 '4 M n o 01 M x CDOj; v1 Cn D OmOo " m 1tE48.67 51+73.16 AP EI- 151.10 � = "P" 51+04.49 AP Elev 148.67 'I 1/ I I I I , I m 1 1«1-n�m "P" 51+54.18 AP I I I Elev 151.10 I I 1 I 1 j j I 1 1 I I I I - m I I I to�X xo I X D Z Z 5 D C= n C Z �J D 0 m n D G� I , Elev 152.18 o m �. N o + = ? N MATCHLINE STA 12+75 1059 -1-Am1 Asmey.na — DAIS PLOTTED 7/1/2026 6:42:23 PM 11.1 1-1— n. 4—, rM DRAFT APPENDIX B: Retaining Wall 35% Estimates ntconsor Page 641 of 1059 Prado Road Interchange: Retaining Wall 1 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 480 $ 240 $ 115,200 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 128 $ 180 $ 23,040 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 2783 $ 160 $ 445,280 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 87 $ 1,520 $ 132,240 5 0 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 8122 $ 2 $ 16,244 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 142 $ 85 $ 12,070 7 0 780401 ARCHITECTURAL TREATMENT SQFT 2783 $ 40 $ 111,320 8 F 833088 TUBULAR HANDRAILING LF 141 $ 300 $ 42,300 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 142 $ 240 $ 34,080 10 0 999990 MOBILIZATION LS LUMP SUM $ - $ 103,530 SUBTOTAL CONTRACT $ 1,035,304 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 000000 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTALSUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 1,035,304 CONTINGENCY 25% $ 258,826 ESCALATION 4 Years at 6.19% Per Year $ 351,425 TOTAL $ 1,646,000 SQFT 1 2783 Subtotal Cost per Square foot $ 373 Total Cost per Square foot $ 592 Page 642 of 1059 Prado Road Interchange: Retaining Wall 2 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 619 $ 240 $ 148,560 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 335 $ 180 $ 60,300 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 3095 $ 160 $ 495,200 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 99 $ 1,520 $ 150,480 5 0 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 9265 $ 2 $ 18,530 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 162 $ 85 $ 13,770 7 0 780401 ARCHITECTURAL TREATMENT SQFT 3095 $ 40 $ 123,800 8 F 833088 TUBULAR HANDRAILING LF 161 $ 300 $ 48,300 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 162 $ 240 $ 38,880 10 0 999990 MOBILIZATION LS LUMP SUM $ - $ 121,980 SUBTOTAL CONTRACT $ 1,219,800 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 000000 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTALSUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 1,219,800 CONTINGENCY 25% $ 304,950 ESCALATION 4 Years at 6.19% Per Year $ 414,051 TOTAL $ 1,939,000 SQFT 1 3095 Subtotal Cost per Square foot $ 395 Total Cost per Square foot $ 627 Page 643 of 1059 Prado Road Interchange: Retaining Wall 3 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 552 $ 240 $ 132,480 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 445 $ 180 $ 80,100 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 2856 $ 160 $ 456,960 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 168 $ 1,520 $ 255,360 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 15714 $ 2 $ 31,428 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 275 $ 85 $ 23,375 7 0 780401 ARCHITECTURAL TREATMENT SQFT 2856 $ 40 $ 114,240 8 F 833088 TUBULAR HANDRAILING LF 274 $ 300 $ 82,200 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 275 $ 240 $ 66,000 10 0 999990 MOBILIZATION LS LUMP SUM - IT 138,016 SUBTOTAL CONTRACT $ 1,380,159 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 1,380,159 CONTINGENCY 25% $ 345,040 ESCALATION 4 Years at 6.19% Per Year $ 468,483 TOTAL $ 2,194,000 SQFT 2856 Subtotal Cost per Square foot $ 484 Total Cost per Square foot $ 769 Page 644 of 1059 Prado Road Interchange: Retaining Wall 4 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 807 $ 240 $ 193,680 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 513 $ 180 $ 92,340 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 3162 $ 160 $ 505,920 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 146 $ 1,520 $ 221,920 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 13655 $ 2 $ 27,310 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 239 $ 85 $ 20,315 7 0 780401 ARCHITECTURAL TREATMENT SQFT 3162 $ 40 $ 126,480 8 F 833088 TUBULAR HANDRAILING LF 238 $ 300 $ 71,400 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 239 $ 240 $ 57,360 10 0 999990 MOBILIZATION LS LUMP SUM - IT 146,303 SUBTOTAL CONTRACT $ 1,463,028 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 1,463,028 CONTINGENCY 25% $ 365,757 ESCALATION 4 Years at 6.19% Per Year $ 496,612 TOTAL $ 2,326,000 SQFT 3162 Subtotal Cost per Square foot $ 463 Total Cost per Square foot $ 736 Page 645 of 1059 Prado Road Interchange: Retaining Wall 5 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 722 $ 240 $ 173,280 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 627 $ 180 $ 112,860 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 5541 $ 160 $ 886,560 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 241 $ 1,520 $ 366,320 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 22648 $ 2 $ 45,296 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 396 $ 85 $ 33,660 7 0 780401 ARCHITECTURAL TREATMENT SQFT 5541 $ 40 $ 221,640 8 F 833088 TUBULAR HANDRAILING LF 395 $ 300 $ 118,500 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 396 $ 240 $ 95,040 10 0 999990 MOBILIZATION LS LUMP SUM - IT 228,128 SUBTOTAL CONTRACT $ 2,281,284 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTALSUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 2,281,284 CONTINGENCY 25% $ 570,321 ESCALATION 4 Years at 6.19% Per Year $ 774,362 TOTAL $ 3,626,000 SQFT 5541 Subtotal Cost per Square foot $ 412 Total Cost per Square foot $ 655 Page 646 of 1059 Prado Road Interchange: Retaining Wall 6 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 719 $ 240 $ 172,560 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 794 $ 180 $ 142,920 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 6283 $ 160 $ 1,005,280 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 242 $ 1,520 $ 367,840 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 22705 $ 2 $ 45,410 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 397 $ 85 $ 33,745 7 0 780401 ARCHITECTURAL TREATMENT SQFT 6283 $ 40 $ 251,320 8 F 833088 TUBULAR HANDRAILING LF 396 $ 300 $ 118,800 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 397 $ 240 $ 95,280 10 0 999990 MOBILIZATION LS LUMP SUM - IT 248,128 SUBTOTAL CONTRACT $ 2,481,283 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 2,481,283 CONTINGENCY 25% $ 620,321 ESCALATION 4 Years at 6.19% Per Year $ 842,250 TOTAL $ 3,944,000 SQFT 1 6283 Subtotal Cost per Square foot $ 395 Total Cost per Square foot $ 628 Page 647 of 1059 Prado Road Interchange: Retaining Wall 7 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 795 $ 240 $ 190,800 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 460 $ 180 $ 82,800 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 5023 $ 160 $ 803,680 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 182 $ 1,520 $ 276,640 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 17072 $ 2 $ 34,144 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 299 $ 85 $ 25,415 7 0 780401 ARCHITECTURAL TREATMENT SQFT 5023 $ 40 $ 200,920 8 F 833088 TUBULAR HANDRAILING LF 297 $ 300 $ 89,100 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 299 $ 240 $ 71,760 10 0 999990 MOBILIZATION LS LUMP SUM - IT 197,251 SUBTOTAL CONTRACT $ 1,972,510 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 1,972,510 CONTINGENCY 25% $ 493,128 ESCALATION 4 Years at 6.19% Per Year $ 669,551 TOTAL $ 3,136,000 SQFT 1 5023 Subtotal Cost per Square foot $ 393 Total Cost per Square foot $ 625 Page 648 of 1059 Prado Road Interchange: Retaining Wall 8 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 2873 $ 240 $ 689,520 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 2984 $ 180 $ 537,120 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 26280 $ 160 $ 4,204,800 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 1075 $ 1,520 $ 1,634,000 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 101086 $ 2 $ 202,172 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 1768 $ 85 $ 150,280 7 0 780401 ARCHITECTURAL TREATMENT SQFT 26280 $ 40 $ 1,051,200 8 F 833088 TUBULAR HANDRAILING LF 1766 $ 300 $ 529,800 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 1768 $ 240 $ 424,320 10 0 999990 MOBILIZATION LS LUMP SUM $ - 1,047,024 SUBTOTAL CONTRACT $ 10,470,236 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 10,470,236 CONTINGENCY 25% $ 2,617,559 ESCALATION 4 Years at 6.19% Per Year $ 3,554,030 TOTAL $ 16,642,000 SQFT 26280 Subtotal Cost per Square foot $ 399 Total Cost per Square foot $ 634 Page 649 of 1059 Prado Road Interchange: Retaining Wall 9 (Alt 1) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 2141 $ 240 $ 513,840 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 1113 $ 180 $ 200,340 3 F 477020 MECHANICALLY STABILIZED EMBANKMENT SQFT 13927 $ 160 $ 2,228,320 4 F 510072 STRUCTURAL CONCRETE, BARRIER SLAB CY 112 $ 1,520 $ 170,240 5 1 0 1 520104 BAR REINFORCING STEEL, BARRIER SLAB LB 10449 $ 2 $ 20,898 6 0 680902 6" PERFORATED PLASTIC PIPE UNDERDRAIN LF 730 $ 85 $ 62,050 7 0 780401 ARCHITECTURAL TREATMENT SQFT 13927 $ 40 $ 557,080 8 F 833094 TUBULAR BICYCLE RAILING LF 182 $ 300 $ 54,600 9 F 839521 CABLE RAILING LF 547 $ 110 $ 60,170 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 183 $ 240 $ 43,920 10 0 999990 MOBILIZATION LS LUMP SUM - Is 434,606 SUBTOTAL CONTRACT $ 4,346,064 SUPPLEMENTAL WORK 11 000000 0 $ - 12 000000 0 $ - 13 000000 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTALSUPPLEMENTALWORK $ - PROJECT SUBTOTAL $ 4,346,064 CONTINGENCY 25% $ 1,086,516 ESCALATION 4 Years at 6.19% Per Year $ 1,475,234 TOTAL $ 6,908,000 SQFT 13927 Subtotal Cost per Square foot $ 313 Total Cost per Square foot $ 497 Page 650 of 1059 DRAFT APPENDIX C: Retaining Wall Alternative Estimates n, consor Page 651 of 1059 Prado Road Interchange: Retaining Wall 1 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 300 $ 240 $ 72,000 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 700 $ 180 $ 126,000 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 2240 $ 325 $ 728,000 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 268 $ 1,300 $ 348,400 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 42595 $ 2 $ 85,190 6 0 780401 ARCHITECTURAL TREATMENT SQFT 2783 $ 50 $ 139,150 7 F 833088 TUBULAR HANDRAILING LF 141 $ 50 $ 7,050 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 142 $ 240 $ 34,080 9 0 999990 MOBILIZATION LS LUMP SUM - $ 171,097 SUBTOTAL CONTRACT $ 1,710,967 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 1,710,967 CONTINGENCY 25% $ 427,742 ESCALATION 4 Years at 6.19% Per Year $ 580,773 TOTAL $ 2,720,000 Page 652 of 1059 Prado Road Interchange: Retaining Wall 2 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 354 $ 240 $ 84,960 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 810 $ 180 $ 145,800 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 2380 $ 325 $ 773,500 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 299 $ 1,300 $ 388,700 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 48069 $ 2 $ 96,138 6 0 780401 ARCHITECTURAL TREATMENT SQFT 3095 $ 50 $ 154,750 7 F 833088 TUBULAR HANDRAILING LF 161 $ 300 $ 48,300 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 162 $ 240 $ 38,880 9 0 999990 MOBILIZATION LS LUMP SUM - $ 192,336 SUBTOTAL CONTRACT $ 1,923,364 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 1,923,364 CONTINGENCY 25% $ 480,841 ESCALATION 4 Years at 6.19% Per Year $ 652,869 TOTAL $ 3,058,000 Page 653 of 1059 Prado Road Interchange: Retaining Wall 3 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 430 $ 240 $ 103,200 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 489 $ 180 $ 88,020 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 1540 $ 325 $ 500,500 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 252 $ 1,300 $ 327,600 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 33646 $ 2 $ 67,292 6 0 780401 ARCHITECTURAL TREATMENT SQFT 2856 $ 50 $ 142,800 7 F 833088 TUBULAR HANDRAILING LF 274 $ 300 $ 82,200 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 275 $ 240 $ 66,000 9 0 999990 MOBILIZATION LS LUMP SUM - $ 153,068 SUBTOTAL CONTRACT $ 1,530,680 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 1,530,680 CONTINGENCY 25% $ 382,670 ESCALATION 4 Years at 6.19% Per Year $ 519,576 TOTAL $ 2,433,000 Page 654 of 1059 Prado Road Interchange: Retaining Wall 4 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 581 $ 240 $ 139,440 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 623 $ 180 $ 112,140 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 1820 $ 325 $ 591,500 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 289 $ 1,300 $ 375,700 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 38944 $ 2 $ 77,888 6 0 780401 ARCHITECTURAL TREATMENT SQFT 3162 $ 50 $ 158,100 7 F 833088 TUBULAR HANDRAILING LF 238 $ 300 $ 71,400 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 239 $ 240 $ 57,360 9 0 999990 MOBILIZATION LS LUMP SUM - $ 175,948 SUBTOTAL CONTRACT $ 1,759,476 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 1,759,476 CONTINGENCY 25% $ 439,869 ESCALATION 4 Years at 6.19% Per Year $ 597,239 TOTAL $ 2,797,000 Page 655 of 1059 Prado Road Interchange: Retaining Wall 5 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 565 $ 240 $ 135,600 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 1039 $ 180 $ 187,020 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 3220 $ 325 $ 1,046,500 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 499 $ 1,300 $ 648,700 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 68961 $ 2 $ 137,922 6 0 780401 ARCHITECTURAL TREATMENT SQFT 5541 $ 50 $ 277,050 7 F 833088 TUBULAR HANDRAILING LF 395 $ 300 $ 118,500 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 396 $ 240 $ 95,040 9 0 999990 MOBILIZATION LS LUMP SUM - $ 294,037 SUBTOTAL CONTRACT $ 2,940,369 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 2,940,369 CONTINGENCY 25% $ 735,092 ESCALATION 4 Years at 6.19% Per Year $ 998,083 TOTAL $ 4,674,000 Page 656 of 1059 Prado Road Interchange: Retaining Wall 6 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 614 $ 240 $ 147,360 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 1220 $ 180 $ 219,600 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 3780 $ 325 $ 1,228,500 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 562 $ 1,300 $ 730,600 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 84550 $ 2 $ 169,100 6 0 780401 ARCHITECTURAL TREATMENT SQFT 6283 $ 50 $ 314,150 7 F 833088 TUBULAR HANDRAILING LF 396 $ 300 $ 118,800 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 397 $ 240 $ 95,280 9 0 999990 MOBILIZATION LS LUMP SUM - $ 335,932 SUBTOTAL CONTRACT $ 3,359,322 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 3,359,322 CONTINGENCY 25% $ 839,831 ESCALATION 4 Years at 6.19% Per Year $ 1,140,293 TOTAL $ 5,340,000 Page 657 of 1059 Prado Road Interchange: Retaining Wall 7 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 576 $ 240 $ 138,240 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 1157 $ 180 $ 208,260 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 3640 $ 325 $ 1,183,000 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 464 $ 1,300 $ 603,200 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 70503 $ 2 $ 141,006 6 0 780401 ARCHITECTURAL TREATMENT SQFT 5023 $ 50 $ 251,150 7 F 833088 TUBULAR HANDRAILING LF 297 $ 300 $ 89,100 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 299 $ 240 $ 71,760 9 0 999990 MOBILIZATION LS LUMP SUM - $ 298,413 SUBTOTAL CONTRACT $ 2,984,129 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 2,984,129 CONTINGENCY 25% $ 746,032 ESCALATION 4 Years at 6.19% Per Year $ 1,012,937 TOTAL $ 4,744,000 Page 658 of 1059 Prado Road Interchange: Retaining Wall 8 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 4279 $ 240 $ 1,026,960 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 5665 $ 180 $ 1,019,700 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 15960 $ 325 $ 5,187,000 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 2432 $ 1,300 $ 3,161,600 5 F 1 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 356873 $ 2 $ 713,746 6 0 780401 ARCHITECTURAL TREATMENT SQFT 26280 $ 50 $ 1,314,000 7 F 833088 TUBULAR HANDRAILING LF 1766 $ 300 $ 529,800 8 F 839741 CONCRETE BARRIER (TYPE 836) LF 1768 $ 240 $ 424,320 9 0 999990 MOBILIZATION LS LUMP SUM - $ 1,486,347 SUBTOTAL CONTRACT $ 14,863,473 SUPPLEMENTAL WORK 10 000000 0 $ 11 000000 0 $ 12 000000 0 $ Bridge Quantities By: A. Hanson Bridge Check By: -- Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ PROJECT SUBTOTAL $ 14,863,473 CONTINGENCY 25% $ 3,715,868 ESCALATION 4 Years at 6.19% Per Year $ 5,045,277 TOTAL $ 23,625,000 Page 659 of 1059 Prado Road Interchange: Retaining Wall 9 (Alt 2) 30% Construction Cost Estimate consor Date 7/2/2026 CON Year 2030 Project. No. D218721CA.00 Project Manager B. Lemon Item No. Item Code Item Description Unit Quantity Unit Price Total 1 F 192037 STRUCTURE EXCAVATION (RETAINING WALL) CY 1308 $ 240 $ 313,920 2 F 193013 STRUCTURE BACKFILL (RETAINING WALL) CY 3513 $ 180 $ 632,340 3 0 490603 24" CAST -IN -DRILLED -HOLE CONCRETE PILING LF 9800 $ 325 $ 3,185,000 4 F 510060 STRUCTURAL CONCRETE, RETAINING WALL CY 1286 $ 1,300 $ 1,671,800 5 1 F 520103 BAR REINFORCING STEEL (RETAINING WALL) LB 201396 $ 2 $ 402,792 6 0 780401 ARCHITECTURAL TREATMENT SQFT 13993 $ 50 $ 699,650 7 F 833088 TUBULAR HANDRAILING LF 182 $ 300 $ 54,600 8 F 839521 CABLE RAILING LF 547 $ 300 $ 164,100 9 F 839741 CONCRETE BARRIER (TYPE 836) LF 183 $ 240 $ 43,920 10 0 999990 MOBILIZATION LS LUMP SUM - $ 796,458 SUBTOTAL CONTRACT $ 7,964,580 SUPPLEMENTAL WORK 11 000000 0 $ 12 000000 0 $ - 13 1 000000 1 0 $ - Bridge Quantities By: A. Hanson Bridge Check By: Road Quantities By: -- Road Check By: -- SUBTOTAL SUPPLEMENTAL WORK $ - PROJECT SUBTOTAL $ 7,964,580 CONTINGENCY 25% $ 1,991,145 ESCALATION 4 Years at 6.19% Per Year $ 2,703,507 TOTAL $ 12,660,000 Page 660 of 1059 DRAFT 0, consor APPENDIX D: GAD Approval Memo Currently under review by Caltrans Page 661 of 1059 DRAFT 0, consor APPENDIX E: Approved BSDS Currently under review by Caltrans Page 662 of 1059 DRAFT ntconsor APPENDIX F: Draft BDHS Page 663 of 1059 F)z rie .suae FUTURE LOCATION OF THE PRADO INTERCHANGE Preliminary Brid Hydraulic Study at Prado Road Interchange Project Project No. 2091613-02 1 Caltrans EA 05-1 H640 City of San Luis Obispo, California June 25, 2026 Page 664 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Executive Summary The proposed U.S. Route 101 (US 101) at Prado Road Interchange Project (Project) includes improvements to extend Prado Road over US 101 to connect with Dalidio Drive, reconstruct the existing US 101 northbound (NB) off -ramp and on -ramp connections with Prado Road, and construct an auxiliary lane on NB US 101 between the Prado Road and Madonna Road interchanges in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the city of San Luis Obispo in the county of San Luis Obispo at Post Mile (PM) 26.8 and improvements on NB US 101 extend from PM 26.5 to PM 27.3. The preferred alternative includes a partial interchange with the proposed Prado Road overcrossing constructed over US 101, a new US 101 NB off -ramp to Prado Road, and a new NB on -ramp from Prado Road. This Bridge Design Hydraulic Study focuses on the new bridges at US 101 NB off -ramp to Prado Road, US 101 NB on -ramp from Prado Road, the Prado Road west overcrossing, and the Prado Road east overcrossing, which are located within the floodplain of San Luis Obispo Creek. The purpose of this Bridge Design Hydraulic Study is to present the design flow characteristics for San Luis Obispo at the Project site, the hydraulic characteristics associated with the pre -Project (existing condition) and post -Project (proposed condition), and the scour potential for the proposed condition. The proposed bridge design was provided by Consor Engineers and the geotechnical data used for the scour analysis were provided by Yeh and Associates, Inc. The 200-year, 100-year, and 50-year recurrence interval design flows for the Project are based on data from the Federal Emergency Management Agency and calculated using United States Geological Survey equations. A two-dimensional (2D) model was developed for the Project to assess the existing and proposed conditions using the design flows. Grading for the Project was provided by Consor Engineers and was used to develop the proposed condition model. Comparison rasters were generated in the hydraulic model to calculate the differences in water surface elevation (WSE) between the proposed and existing conditions. There are localized increases and decreases in WSE within the vicinity of the Project improvements. During the 100- year storm event, the maximum increase in WSE is 2.4 feet (ft), and it occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in WSE is 1.9 ft, and it also occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. Cross section lines were used to extract data from the 2D model results. The WSEs were extracted along the upstream faces of the Project bridges. The maximum WSEs were extracted, and an average of WSEs along the line were also estimated. The maximum WSE in the proposed condition compared with the maximum WSE in the existing condition increases by 0.1 ft or less. The average WSE in the proposed condition compared with the average WSE in the existing condition increases by 0.3 ft or less. The applicable freeboard criteria for the Project require that the bridges pass the 100-year flow without freeboard and the 50-year flow with 2 ft of freeboard. Based on the results of the hydraulic analysis, the Project bridges will meet the freeboard requirements. The scour potential was evaluated for the proposed bridges using the scour design flood, which is the 100-year flow, and the scour check flood, which is the 200-year flow. Long-term bed elevation changes (degradation) are typically based on historical data at the bridge site. Bridge Inspection Reports do not exist at the Project, and long-term bed elevation change was not assessed for the i,Pnoge pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Project. Based on the scour analysis for the design flood, the contraction scour depths range from 0 to 1.7 ft depending on support location, and the local scour depths range from 1.4 to 11.0 ft depending on the support location. The associated long-term scour elevation for the design flood ranges from 127.2 ft North American Vertical Datum of 1988 (NAVD 88) to 133.0 ft NAVD 88. Based on the scour analysis for the check flood, the contraction scour depths range from 0 to 2.1 ft depending on support location, and the local scour depths range from 2.1 to 13.0 ft depending on the support location. The associated long-term scour elevation for the check flood ranges from 126.9 to 133.0 ft NAVD 88. The foundations are required to be designed to withstand the effects of scour with pile resistance accounting for potential material loss due to scour. ii I June 25, 2026 Page 666 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Contents Executive Summary 1 General Description............................................................................................................................. 1 1.1 Project Description.................................................................................................................... 1 1.2 Study Purpose........................................................................................................................... 1 1.3 Key Tasks.................................................................................................................................. 1 1.4 Design Criteria........................................................................................................................... 7 1.4.1 Hydraulic Design Criteria............................................................................................. 7 1.4.2 Foundation Criteria....................................................................................................... 8 1.4.3 Scour Design Criteria................................................................................................... 9 1.5 Vertical Datum...........................................................................................................................9 2 Geographic Setting............................................................................................................................ 10 2.1 Geographic Location............................................................................................................... 10 2.2 Watershed Description............................................................................................................ 10 3 Hydrologic Assessment..................................................................................................................... 13 4 Hydraulic Analysis............................................................................................................................. 15 4.1 Design Tools........................................................................................................................... 15 4.2 Hydraulic Model Development................................................................................................ 15 4.2.1 Computational Grid/2D Flow Areas............................................................................ 15 4.2.2 Model Boundary Conditions....................................................................................... 15 4.2.3 Existing Condition Geometry...................................................................................... 17 4.2.4 Proposed Condition Geometry Adjustments.............................................................. 21 4.3 Hydraulic Model Results.......................................................................................................... 23 4.3.1 Water Surface Elevations........................................................................................... 26 4.3.2 Freeboard................................................................................................................... 36 4.3.3 Flow Velocities........................................................................................................... 37 5 Scour Analysis................................................................................................................................... 40 5.1 Caltrans Bridge Inspection Reports........................................................................................40 5.2 Existing Channel Bed.............................................................................................................. 41 5.3 Long -Term Bed Elevation Change..........................................................................................41 5.4 Contraction Scour....................................................................................................................41 5.5 Pier Scour................................................................................................................................ 42 5.6 Abutment Scour....................................................................................................................... 43 5.7 Total Scour.............................................................................................................................. 44 6 References........................................................................................................................................ 47 Tables Table 1. Watershed Drainage Areas........................................................................................................... 11 Table 2. Hydrologic Data Summary for Project........................................................................................... 13 Table 3. Data Sources Used to Develop the Hydraulic Model Geometry ................................................... 17 Table4. Manning's n Values.......................................................................................................................20 JurPe@g@o07iiPf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 5. River Stations along San Luis Obispo Creek at Geographical Locations ..................................... 23 Table 6. 100-year Water Surface Elevations Upstream of Bridges............................................................ 34 Table 7. 50-year Water Surface Elevations Upstream of Bridges.............................................................. 34 Table 8. Hydrologic Summary Table for Prado Road West Overcrossing................................................. 35 Table 9. Hydrologic Summary Table for Prado Road East Overcrossing.................................................. 35 Table 10. Hydrologic Summary Table for US 101 NB Off-Ramp................................................................ 35 Table 11. Hydrologic Summary Table for US 101 NB On-Ramp................................................................ 36 Table 12. 100-Year Water Surface Elevations and Freeboard................................................................... 36 Table 13. 50-Year Water Surface Elevations and Freeboard..................................................................... 36 Table 14. Summary of Structures within Floodplain and Type of Scour Assessed .................................... 40 Table 15. Calculated Contraction Scour Depths.........................................................................................42 Table 16. Calculated Local Pier Scour Depths........................................................................................... 43 Table 17. Calculated Local Abutment (and MSE Wall) Scour Depths........................................................44 Table 18. Scour Summary Table: Prado Road West Overcrossing...........................................................44 Table 19. Scour Summary Table: Prado Road East Overcrossing............................................................44 Table 20. Scour Summary Table: US 101 NB Off-Ramp...........................................................................45 Table 21. Scour Summary Table: US 101 NB On-Ramp...........................................................................45 Table 22. Scour Data Table: Prado Road West Overcrossing................................................................... 45 Table 23. Scour Data Table: Prado Road East Overcrossing.................................................................... 45 Table 24. Scour Data Table: US 101 NB Off-Ramp...................................................................................46 Table 25. Scour Data Table: US 101 NB On-Ramp...................................................................................46 Figures Figure1. Project Location Map..................................................................................................................... 2 Figure2. Project Vicinity Map....................................................................................................................... 3 Figure 3. Proposed Prado Road Interchange Bridges General Plan............................................................4 Figure 4. Proposed US 101 NB Off -Ramp Bridge General Plan.................................................................. 5 Figure 5. Proposed US 101 NB On -Ramp Bridge General Plan.................................................................. 6 Figure 6. San Luis Obispo Creek Watershed Map..................................................................................... 11 Figure 7. Project Watershed Map............................................................................................................... 12 Figure 8. 2D Flow Areas and Boundary Conditions.................................................................................... 16 Figure 9. Bridges as SA/2D Connections in Hydraulic Model..................................................................... 19 Figure 10.Terrain Comparison in Vicinity of Project................................................................................... 22 Figure 11. Location of Profile Used to Summarize Model Results............................................................. 24 Figure 12. Locations of Cross Sections Used to Summarize Model Results ............................................. 25 Figure 13. Existing Condition 100-year Flow Depths.................................................................................. 26 Figure 14. Existing Condition 100-year Flow Depths at Project Vicinity ..................................................... 28 Figure 15. San Luis Obispo Creek 100-Year Water Surface Profile within Model Domain ........................29 Figure 16. San Luis Obispo Creek 50-Year Water Surface Profile within Model Domain .......................... 30 Figure 17. Changes in WSE within the 2D Model Domain......................................................................... 31 Figure 18. 100-year WSE Comparison (Proposed - Existing) within Project Vicinity ................................. 32 Figure 19. 50-year WSE Comparison (Proposed - Existing) within Project Vicinity ................................... 33 Figure 20. Changes in Velocities within the 2D Model Domain.................................................................. 38 Figure 21. 100-year Velocity Comparison (Proposed - Existing) within Project Vicinity ............................. 39 iv I June 25, 2026 Page 668 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 22. 50-year Velocity Comparison (Proposed - Existing) within Project Vicinity ............................... 39 Appendices Appendix A. FIS Excerpts Appendix B. HEC-RAS Model Results: Grid Extents View Appendix C. HEC-RAS Model Results: Project Vicinity View Appendix D. Scour Calculations JuPeag,g6Oq pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Abbreviations 1 D one-dimensional 2D two-dimensional AASHTO American Association of State Highway and Transportation Officials AZ Arizona BDS Bridge Design Specifications BFE base flood elevation CA California Caltrans California Department of Transportation CFR Code of Federal Regulations cfs cubic feet per second City City of San Luis Obispo cm centimeter County County of San Luis Obispo CPT cone penetration test DDM Drainage Design Manual DEM Digital Elevation Model FEMA Federal Emergency Management Agency FHWA Federal Highway Administration FIRM Flood Insurance Rate Map FIS Flood Insurance Study ft feet, foot ft/s feet per second HDM Highway Design Manual HEC-18 Hydraulic Engineering Circular No. 18 HEC-RAS Hydrologic Engineering Center's River Analysis System LRFD Load and Resistance Factor Design m meter mi mile MSE mechanically stabilized earth NAVD 88 North American Vertical Datum of 1988 NB northbound NCHRP National Cooperative Highway Research Program NFIP National Flood Insurance Program OPR Original Product Resolution PG&E Pacific Gas and Electric PM Post Mile Project U.S. Route 101 (US 101) at Prado Road Interchange Project QL2 Quality Level 2 R9 Region 9 RS river station SA Storage Area US 101 U.S. Route 101 USACE United States Army Corps of Engineers USGS United States Geological Survey WSE water surface elevation vi I June 25, 2026 Page 670 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project This page is intentionally left blank. JunpAggA711,iipf 1059 Page 672 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 1 General Description 1.1 Project Description The proposed U.S. Route 101 (US 101) at Prado Road Interchange Project (Project) includes improvements to extend Prado Road over US 101 to connect with Dalidio Drive, reconstruct the existing US 101 northbound (NB) off -ramp and on -ramp connections with Prado Road, and construct an auxiliary lane on NB US 101 between the Prado Road and Madonna Road interchanges in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the city of San Luis Obispo in the county of San Luis Obispo at Post Mile (PM) 26.8 and improvements on NB US 101 extend from PM 26.5 to PM 27.3. The preferred alternative includes a partial interchange with the proposed Prado Road overcrossing constructed over US 101, a new US 101 NB off -ramp to Prado Road, and a new NB on -ramp from Prado Road. The Project location map is shown in Figure 1. These bridges are shown in the Project vicinity map in Figure 2. 1.2 Study Purpose This Bridge Design Hydraulic Study focuses on the new bridges at the Prado Road overcrossing (west and east overcrossing bridges), US 101 NB off -ramp to Prado Road, and the US 101 NB on -ramp from Prado Road, which are located within the floodplain of San Luis Obispo Creek. The general plans for the proposed bridges are shown in Figure 3, Figure 4, and Figure 5. The purpose of this Bridge Design Hydraulic Study is to present the design flow characteristics for San Luis Obispo at the Project, the hydraulic characteristics associated with the pre -Project (existing condition) and post -Project (proposed condition), and the scour potential for the proposed condition. As part of a separate project, the Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0l07), which is located east of the proposed Project bridges, is proposed to be replaced. This Bridge Design Hydraulic Study incorporates data from the Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0107) replacement, but the bridge is not part of this study. 1.3 Key Tasks Key tasks performed in this study included: 1) a review of available hydrologic data, 2) a hydrologic analysis, 3) a hydraulic analysis to determine design water surface elevations (WSE) and flow velocities for the existing and proposed conditions, 4) and a scour analysis to estimate potential scour depths for the proposed condition. .lupeag,Q67� ,pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 1. Project Location Map El Chorro Regional Park s. .J4 t 1 °,r OSOs Gai �P y Goldtree F San Luis !� Obispo / 0 Project Location Mine Hill San Luis Obispo County Regional Airport S'FN N 1\ 1 �/ L t♦ I t li O ,. � - Edna 0 0 1,3 1„1 X. ESRI• NASA. NGA, USGS, FEMA, SOURCES' ESRI. TOMTOM, GARMIN, FAO, NOAA. USGS. - i Tiber (C) OPENSTREETMAP CONTRIBUTORS, AND ' THE GIS USER COMMUNITY S Source: Esri 2 1 June 25, 2026 Page 674 of 1059 m N G7 N O N W cn CDc m ;moo / I I cs CD ODT a N ;z= o 0 0 �• =oE o 0 0 m c o °m Q o, N o j �► m CD 2. Zcm a a < C7 pzv .� -0 n 0 nz0 h in 0 O m a CD f2. 0 7 < O cn �� W n fD 'r CD CD `G CD �D N - FRI A ` (D W W q O 2 2wz1 .r ♦ .. 0. O / ID Ln ` 0 C: f LO W Y i 9i � y / mac.•. m 3 z : Al 0(D3z mW � < M , f � / AR, o mwbmw%�. do y Ln w O Wc fll A .. K, m oo \\ m�4 0 \ « O o \ o. 0 r`D (D nM < r O M (D O � atg Liu.0 - +,p �fil C 03 m p� W QQ 0 CD vo Qy 0_ �Q v (� o Cl) D- c �< Aj Page 675 of 1059 a�� a S♦ d' �S 3ga �T Hyuv e.5dU« > � 9 Q r r .MIA V n S ]09 s� Y J a1J "' O" Page 676 of 1059 |� 1 �&� . E _ . 15 » 2 . 2 � | « - � ■) c . ¥ | ¥■ � , . I \ §§! , A «, « p . _ / Sir \ gg y e ; � ) , 2 qQ |{f ) , ■�§ I�, ® m �§/ 2 . o�� ;■, � _ 41 1 1- , • * . V lei Page 677 0 1059 Tlll� '- J. 0 z _ )k� A J? \Om Z A z z m OR �, >> \\} m z Y Page 678 0 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 1.4 Design Criteria The following criteria were used in the design of the proposed bridges. 1.4.1 Hydraulic Design Criteria 1.4.1.1 Federal Highway Administration (FHWA) Standards Per Title 23 Chapter I Subchapter G Part 650 Subpart A Section 650.115 (23 Code of Federal Regulations [CFR] 650.115), "freeboard shall be provided, where practicable, to protect bridge structures from debris- and scour -related failure." (FHWA 2026). 1.4.1.2 Caltrans Standards From Memo to Designers 16-1 Hydraulic Design for Structures over Waterways, the proposed bridge soffit should provide adequate freeboard to pass anticipated drift for the 50-year design flood, or to pass the 100-year base flood without freeboard, whichever is greater (Caltrans 2017). From Chapter 820 of the Caltrans' Highway Design Manual (HDM), the criterion for the hydraulic design of bridges is that they be designed to pass the 2% probability of annual exceedance flow (50-year design discharge) with adequate freeboard to pass anticipated bedload and debris. Two (2) feet (ft) of freeboard is commonly used in bridge designs. Alternatively, the bridge can also be designed to pass the 1 % probability of annual exceedance flow (100-year design discharge, or base flood). No freeboard is added to the base flood (Caltrans 2025a). 1.4.1.3 County of San Luis Obispo Standards The Public Improvement Standards (San Luis Obispo County [County] Department of Public Works 2022) did not specify bridge freeboard criteria. However, the Public Improvement Standards does include a list of federal and state supplemental design standards, and includes a hierarchy to indicate which standards should take precedence. According to the Public Improvement Standards, "[i]f the County standard does not address the issue, then the appropriate State standard (Caltrans) governs. In cases where the County and State standards do not discuss the design issue, then the appropriate Federal standard governs." (San Luis Obispo County Department of Public Works 2022) 1.4.1.4 City of San Luis Obispo Standards The City of San Luis Obispo (City) developed a Waterway Management Plan comprised of three volumes, which discuss watershed management, management and maintenance for waterways in the San Luis Obispo Creek watershed, and policies for floodplain management with the City. The Waterway Management Plan also includes guidelines for designs of channels, storm drain systems, stormwater facilities, and erosion control, but does not specify bridge freeboard requirements. While bridge freeboard is not specified, the San Luis Obispo Creek Waterway Management Plan Volume III Drainage Design Manual (DDM) indicates that the San Luis Obispo Creek channel design requirement is for the 50-year flow in the reach from Madonna Road to JuPeWO79 pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Prado Road and 100-year flow in the reach from Prado Road to the confluence with Prefumo Creek (City of San Luis Obispo Department of Public Works and County of San Luis Obispo Flood Control District — Zone 9 2003). 1.4.1.5 Project Freeboard Criteria The City and County do not specify freeboard criteria for the hydraulic design of bridges. FHWA and Caltrans freeboard criteria are applicable to the Project: both of which require that bridges pass the 100-year design flow without additional freeboard, or the 50-year design flow with adequate freeboard to pass drift and debris (with 2 ft commonly used). The Project has been designed to meet FHWA and Caltrans freeboard criteria. 1.4.2 Foundation Criteria Bridges must be designed per the California Amendments to the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (BDS) (2017 Eighth Edition) (California Department of Transportation [Caltrans] 2019). The California Amendments to the AASHTO LRFD BDS (2017 Eighth Edition) Section 2.6.3 defers to state requirements for hydraulic studies. Per the California Amendments to the AASHTO LRFD BDS (2017 Eighth Edition) (Caltrans 2019), foundations should be designed to withstand the conditions of scour. Caltrans' Memo to Designers 16-1 (Caltrans 2017) provides additional guidance on foundation placement: The top of a spread footing must be placed at or below the anticipated total scour (Degradation + Contraction + Local) elevation (LRFD 2.6.4.4.2 and LRFD-BDS-CA Figure C2.6.4.4.2-1) unless founded on competent, scour -resistant bedrock. The top of a pile cap footing must be placed at or below the estimated degradation plus contraction scour depth (LRFD 2.6.4.4.2 and LRFD-BDS-CA Figure C2.6.4.4.2- 2). The bottom of a pile cap footing should be placed at or below the anticipated Total Scour elevation. (Caltrans 2017) Bridge Design Memo 10.7 (Caltrans 2025b) includes information pertaining to the design of driven piles used as deep foundations. According to AASHTO LRFD BDS, deep foundations "shall meet requirements for Service, Strength, Extreme Event." The pile foundations are required to be designed to withstand the effects of scour with pile resistance accounting for potential material loss due to scour. If the abutments are designed as piers, the foundations should be designed such that they are stable during the scour conditions, including loss of approach fill. This assumes an unsupported pile length above the total scour elevation. Structure Technical Policy 2.6 (STP 2.6) addresses design criteria for the hydraulic design and scour criteria for new bridges and bridge widenings over waterways (Caltrans 2025c). Similarly to Memo to Designers 16-1, STP 2.6 refers to BDS, but also requires that the foundations consider the check flood conditions based on frequencies up to the 200-year flood. Per STP 2.6, "[t]he design of piers shall ignore the presence and function of scour countermeasures, and the streambed material above the scour elevation is 8 1 June 25, 2026 Page 680 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project assumed to have been removed." The following requirements apply to the deep foundations at the piers and abutments: Piers supported on pile groups shall be located so that the bottom of the pile cap is below the scour elevation determined for the Scour Design Flood and shall satisfy the Extreme Event II limit state for scour conditions determined for the Scour (Design) Check Flood. For abutments supported on deep foundations, the presence and function of scour countermeasures shall not be considered, and the streambed material above the scour elevation is assumed to have been removed (except as noted below). The foundations shall be located so that the bottom of the pile cap is below the scour elevation determined for the Scour Design Flood and shall satisfy the Extreme Event II limit state for scour conditions determined for the Scour (Design) Check Flood. However, the abutment foundation may be designed assuming the soil protected by the scour countermeasure remains in place under all limit states, except the Extreme Event II limit state for the Scour (Design) Check Flood, if the following criteria are satisfied: • The current or projected annualized average daily traffic (AADT) multiplied by the detour length is less than or equal to 10,000 vehicle -miles, and the AADT is less than or equal to 2000 vehicles. The detour route shall not include scour - critical bridges. • The scour countermeasure is properly designed as described in HEC-23 and TechBrief FHWA-HIF-23-048 (Caltrans 2025c) The exception for abutment foundation design does not apply to the Project site because the AADT exceeds the value noted and scour countermeasures are not proposed for the Project. 1.4.3 Scour Design Criteria The evaluation of potential scour at the proposed bridge followed the criteria described in the FHWA's Hydraulic Engineering Circular No. 18 (HEC-18), "Evaluating Scour at Bridges" (FHWA 2012). The evaluation of potential scour was based on the hydraulic characteristics of the scour design flood, which is the 100-year design discharge. Per STP 2.6, scour was also evaluated for the check flood, which is the 200-year design discharge. The total scour was estimated based upon the cumulative effects of the long- term bed elevation change, general (contraction) scour, and local scour. 1.5 Vertical Datum The Project references the North American Vertical Datum of 1988 (NAVD 88). JuPeag,g6$J epf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 2 Geographic Setting 2.1 Geographic Location The intersection of Dalidio Drive with Froom Ranch Way at the western limits of the Project is at 35015'30.44" North latitude and 120°40'36.14" West longitude (Google Earth 2025). The intersection of Prado Road with South Higuera Street at the eastern limits of the Project is at 35'15'16.62" North latitude and 120°40'8.42" West longitude (Google Earth 2025). The Project bridges are located within the San Luis Obispo Creek floodplain within the city of San Luis Obispo. The Project bridges are at the intersection of Prado Road with US 101. The Prado Road bridge over the San Luis Obispo Creek (Existing Bridge Number 49C0107) bridge crossing is located east of the proposed Project bridges. 2.2 Watershed Description The Project site is within the San Luis Obispo Creek watershed. The San Luis Obispo Creek watershed is approximately 84-square miles (mi) and located within the Estero Bay Hydrologic Unit, Point Buchon Hydrologic Area, and San Luis Obispo Creek sub- area. The upstream limits are in the Santa Lucia Range northeast of San Luis Obispo. The San Luis Obispo Creek generally flows southwest and discharges into the Pacific Ocean at Avila Beach. Prefumo Creek and Froom Creek are tributaries to San Luis Obispo Creek downstream of the Project location. The Project site is located approximately 50 ft from San Luis Obispo Creek in the floodplain where surface water flows from San Luis Obispo Creek toward Prefumo Creek located approximately 0.25 mi west of the Project site. See Figure 6 for a map of the San Luis Obispo Creek watershed. The watershed drainage areas for San Luis Obispo Creek, Prefumo Creek, and Froom Creek are shown in Table 1 and the associated watershed delineations are shown in Figure 7. These Project watersheds are associated with the flows at the upstream boundary conditions used in the hydraulic model; the flows are discussed later in Section 3 and the hydraulic model is discussed later in Section 4. The San Luis Obispo Creek watershed area associated with Prado Road is also shown in Figure 7. 10 1 June 25, 2026 Page 682 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 6. San Luis Obispo Creek Watershed Map „ I Mid Salinas River - Atascadero Morro Bay Area Watershed Watershed San Lui San Luis Obi Arroyo Grande Obispo—` Project Creek Watershed Creek Location Prefumo Creek Froom Creek San L is Obispo Cree atershed Coastal Irish Hills Watershed Pismo Creek 0. Pach Watershed N California State Parks, Esn, HERE, Garmin, SafeGraph, A 0 1 25 2.5 5 Miles METI/NASA, USGS, Bureau of Land Management, EPA, Fi_ �� � Beach NIPS, USDA 227 Data Source: Watersheds — County Department of Public Works (2014); Creeks — HDR (2019a) Table 1. Watershed Drainage Areas San Luis Obispo Creek At intersection of Marsh Street and Archer Street At Prado Road Prefumo Creek Upstream of confluence of San Luis Obispo Creek Froom Creek Upstream of confluence of San Luis Obispo Creek Source: United States Geological Survey (USGS) 2026a 24.7 14.2 1.7 JunF J4g31pf 1059 N CD CD N O1 N O N d) +Zn ;Dz � y DSO N A. 3 Z Z ?fir c Zy ONO �^ ZP ZN yzv Dn0 cm� Paz y x H a N 9Nc I m Z A ta3m Dy A' mPm mmy nap 9�m nDA Oym ? � O pAm m m y r0 C A O .z A m A `^ z Dian cam �mm �nmz O N C1 C O m� AP: Owz O?v N C Imz ZOA y>n < x Z O mo � 3 D D .2. x. m 0 A C n r► 09A $ 0= O ..� 1 j N n Q Pw 0 O. c m A N T m ^' A ; nD O0 3 Czz <m y C O i c0 AA 0. me N N P TN y- AZ D r N p 6] CI fft fD O O o 3m r N C ? m r N C c 3 C� in m O r m m n p ID o p n a N C. w C P 0. 0 D61 p� n COO n m C) y C) m 0 O CD CD N O F M y F S 00 to Cl y n m n R 3 o o r- CO c o NeF o � 0 m 0 W N m Q C -u C/)io 03 N W n Q Oca 17 m 00 N O n N 7 � fD 7 n = w O- D v c C O. (D Q Page 684 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 3 Hydrologic Assessment The streams that were assessed for the Project include San Luis Obispo Creek, Prefumo Creek, and Froom Creek. Peak flows for San Luis Obispo Creek and Prefumo Creek were obtained from the Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS); however, the FIS did not include peak flows at Froom Creek. The peak flows at Froom Creek were calculated using the USGS regional regression (flood -frequency) equations. The flood -frequency equations were developed by the USGS and based on analysis of data from gage stations. California is divided into six regions. These flood -frequency equations are generally used to estimate stream flow for ungaged sites that are not affected by substantial urban development and that are natural (unregulated) streams. On July 18, 2012, USGS issued Methods for Determining Magnitude and Frequency of Floods in California, Based on Data through Water Year 2006 (Gotvald et al. 2012), which contains updated regional flood -frequency equations, and revised the boundaries of the six unique regions within California. These equations are based on annual peak -flow data through water year 2006 for 771 streamflow-gaging stations in California with 10 or more years of data. The updated equations were used in support of the hydrologic analysis of Froom Creek. Basin characteristics for the Froom Creek watershed at US 101 (just upstream of its confluence with San Luis Obispo Creek) were obtained from StreamStats (USGS 2026a). The drainage area of Froom Creek at US 101 is 1.7 square mi (see Section 2.1) and the mean annual precipitation is 21.2 inches (USGS 2026a). See Table 2, which presents the calculated 50-year, 100-year, and 200-year flows for Froom Creek. Table 2. Hydrologic Data Summary for Project San Luis At intersection of Marsh FIS 10,300 13,500 17,040 Obispo Creek Street and Archer Street Prefumo Upstream of confluence FIS 2,400 3,100 3,930 Creek of San Luis Obispo Creek Froom Creek Upstream of confluence USGS 278 358 445 of San Luis Obispo Creek Note: the 100-year and 50-year flows were taken directly from the FIS for San Luis Obispo Creek and Prefumo Creek. The 200-year flows were extrapolated based on the ratios of the FEMA to regional regression estimates and using the extrapolated ratio to estimate a FEMA 200-year flow. FEMA is the nationwide administrator of the National Flood Insurance Program (NFIP). As part of the NFIP, typically, each participating county (or community) has a FIS, which is used to locally develop Flood Insurance Rate Maps (FIRM) and base flood elevations (BFE). The FIS for San Luis Obispo County, California and Incorporated Areas included peak flows along San Luis Obispo Creek and Prefumo Creek for the 100-year, 50-year, and 10-year return periods. The FIS included multiple flow change locations along the creeks (excerpts from the FIS are included in Appendix A); the intersection of Marsh Street and Archer Street is located upstream/north of the Project site approximately at June A�5:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project M the upstream boundary of the two-dimensional (21D) model domain (see Section 4 for additional details related to the hydraulic model). The 10-year, 50-year, 100-year, and 200-year flows for San Luis Obispo Creek and Prefumo Creek were also calculated using the USGS regional regression equations. The ratios of the flows listed in the FEMA FIS and the USGS regional regression estimates for the 10-year, 50-year, and 100-year flows were used to extrapolate a ratio for the 200- year flow, and the ratio was multiplied by the USGS regional regression estimate for the 200-year flow to estimate an extrapolated 200-year FEMA flow for the two streams. Table 2 presents the 100-year and 50-year peak flows from the FIS for San Luis Obispo - and Prefumo creeks (FEMA 2024) and the extrapolated 200-year flows for the two streams. 14 1 June 25, 2026 Page 686 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4 Hydraulic Analysis The following sections discuss the development of the hydraulic models and summarize the results for the existing and proposed conditions. The model results are included in Appendix B and Appendix C. 4.1 Design Tools The hydraulic analyses were performed for the existing and proposed conditions using the United States Army Corps of Engineers' (USACE) Hydrologic Engineering Center's River Analysis System (HEC-RAS) modeling software, Version 6.6 (USACE 2024). 4.2 Hydraulic Model Development A 2D model was developed for the Project to assess the existing and proposed conditions. The following sections describe the parameters used in the hydraulic model development. The hydraulic modeling utilized the 2D hydraulic model that was developed as part of the Floodplain Evaluation Report from the previous phase of the Project (HDR 2023) as the base model. The model was refined to include updated information as available and to incorporate additional detailed Project improvement details. 4.2.1 Computational Grid/21D Flow Areas The Project was modeled using a single 2D flow area in the vicinity of the Project (see Figure 8). The 2D mesh was used in the hydraulic model to encompass San Luis Obispo Creek as well as the Prefumo Creek tributary and Froom Creek tributary, both of which contribute flows to San Luis Obispo Creek. The mesh in the 2D hydraulic model has an average cell size of 50 ft and included a total of 54,568 cells that are the same in both the existing and proposed conditions model geometries. Refinements to the computational grid were made by placing breaklines and refinement regions as needed to provide added definition in controlling flow direction through the creeks, around roads, piers, approach ramps, and abutments for the Project, which are modeled in the terrain. The computational points and breaklines were copied from the proposed condition geometry to the existing condition geometry so that both geometries have the same computational grid to minimize the impacts of model differences on the results. 4.2.2 Model Boundary Conditions Boundary conditions of the 2D mesh areas were placed at the upstream and downstream ends of the channels where flows could enter and exit the model during the simulated flows. Figure 8 shows the 2D flow area cells included in the mesh of the model domain as well as the upstream and downstream boundary condition locations. The model has three upstream boundary conditions and one downstream boundary condition. JunPA�719f 1059 8 Wcn o v c � C r n� n0. o �• D� n 0 o p o CD v i.... .... W-n 0 0 o Q 3 v n c) m o 77 �c o CD v W-u o m c CL3 o nCD o m C Q 7 - -c o-a D cn CD v 3 rll m I FU I 6) m z v CO N o 0 -oa c -n o O cCD D 0 m o CD' n n CD o WU) o v c � CL C r v cn. ns o �• =� �o 0 c D-0 U) cu v 3 m cz-u c�cnfD c 83 m vv P co N� N n Q v �� -n N 0 Q T. ID �Q Dv m m � cn a (CL W 0 c Q. 2) Q n 0 0 U) Page 688 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.2.3 4.2.3.1 San Luis Obispo Creek has an upstream boundary approximately 220 ft upstream of the Pacific Gas and Electric (PG&E) access bridge near Lower Marsh Street. The upstream boundary for Prefumo Creek is at the downstream face of the Madonna Road bridge. Froom Creek has an upstream boundary in the foothills southwest of Los Osos Valley Road at approximately 275 ft NAVD 88. Both Prefumo Creek and Froom Creek are tributaries to San Luis Obispo Creek. The upstream boundary conditions were set to constant inflow values equal to the peak flows (see Table 2 in Section 3 for a summary of the peak flows) at the respective creek locations. The downstream boundary of the model is on San Luis Obispo Creek approximately 1,800 ft downstream of the Los Osos Valley Road over San Luis Obispo Creek bridge. The downstream boundary condition was set to a slope of 0.006 ft/ft, which was measured from the Original Product Resolution (OPR) Digital Elevation Model (DEM) (USGS 2018) along the boundary edge of the model domain. Existing Condition Geometry The geometries for the hydraulic model were developed using a combination of the following data sources listed in Table 3. Table 3. Data Sources Used to Develop the Hydraulic Model Geometry Short Description Source of D. 1 OPR California (CA) Arizona (AZ) FEMA Region 9 (R9) lidar 2017 2 Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0107) 3 Project topography based on aerial mapping with survey conforms 4 Topography with newly added digital terrain model in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road 5 Prefumo Creek 6 Froom Ranch development 7 Project grading for approaches and Elks Lane 8 Project linework for abutments, MSE walls, and piers USGS Wallace Group Wallace Group Wallace Group HDR HDR Consor Engineers Consor Engineers The data sources listed in Table 3 from USGS, Wallace Group, and HDR (numbers 1 through 6) were used to develop the existing condition hydraulic model and as a basis for the proposed condition hydraulic model. The proposed condition incorporated the proposed Project improvements based on the data sources listed in Table 3 that were provided by Consor Engineers (numbers 7 and 8). These data sources are described in greater detail in Section 4.2.3. Terrain The terrain for the existing condition hydraulic model utilized the data sources from USGS, Wallace Group, and HDR (see Table 3). JunPgggAqg1pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project According to the "CA AZ FEMA R9 2017 D18 Airborne Lidar Report" (USGS 2019), the OPR DEM encompasses areas within California and Arizona; the target resolution of the OPR DEM for the portion of the data within California was Quality Level 2 (QL2) with 2 points per square meter and 0.7-meter (m) nominal point spacing. QL2 lidar has a vertical accuracy of 10 centimeters (cm) and a DEM cell size of 1 m. The OPR DEM (USGS 2018) terrain was imported into HEC-RAS using the function in the RAS Mapper tool built-in to HEC-RAS (USACE 2024). The following Project -specific terrain sources from Wallace Group, and HDR were used to supplement the OPR DEM (USGS 2018). The Prado Road bridge over San Luis Obispo Creek (Existing Bridge Number 49C0l07), which is located east of the proposed Project bridges is proposed to be replaced as a part of a separate project. The terrain for San Luis Obispo Creek in the vicinity of Prado Road at Existing Bridge Number 49C0107 included the existing terrain incorporated with the proposed improvements for the Prado Road bridge over San Luis Obispo Creek bridge replacement project, and was provided to the Project team (Wallace Group 2025a). This bridge is assumed to be replaced prior to the Project, and was modeled as a storage area (SA)/2D connection using data from the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). Topography was developed for the Project based on aerial mapping with areas of survey conforms and augmentation from ground surveys (Wallace Group 2025b), which encompasses the areas of improvement within the Project limits. Additional topography with newly added digital terrain model was used to supplement the area in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road (Wallace Group 2025c), which is in an area west of US 101 and west of the Project improvements. Cross sections from Prefumo Creek were converted to a 2D surface using survey data that was used to develop the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023), to encompass the area of Prefumo Creek at its confluence with San Luis Obispo Creek, which is located south of the Project improvements. The Froom Ranch development is located west of the agricultural portion of the San Luis Ranch, and the terrain that encompasses that area was clipped from a terrain that was used in the development of the 2-Dimensional Hydraulic Model Update Draft Report (HDR 2019b). The existing merged terrain within the model domain is shown in Figure 9. 4.2.3.2 Bridges Existing bridges were modeled as SA/2D connections as described in the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). The structures are shown in Figure 9. 18 1 June 25, 2026 Page 690 of 1059 O Cl) c � � r v _ (. ncr 0 -. Q' O 00 :3 O m v 3 CD W -n O o O EL v n c) m O T. C O cn =3 r. m v I m z N T CC) C/) Q0 m 'O 0 (D D CL C N 0 O O v CD 0 n O Q O D � O 5 cam' c m co W Q t4 m N cu N cn 0 0 O m n _rt O N 2 CL m c n 9 O CL m c Cl) 03 m � v W nQ o X 0 0 0 v (COD � cQ m � MQ m m _. o Cl) `m c �< Aj Page 691 of 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 4.2.3.3 Manning's Roughness Coefficients Manning's roughness coefficients (n values) were used in the hydraulic model to estimate energy losses in the flow due to friction. Table 4 lists the Manning's n values that were used to represent land cover conditions within the hydraulic model domain. Manning's n values were selected based upon standard documented values of similar stream conditions from aerial imagery; common channel types are extensively researched in Open -Channel Hydraulics (Chow, V.T. 1959) and have been compiled in the HEC-RAS River Analysis System, Hydraulic Reference Manual (USACE 2016). The Manning's n value used to represent the areas surrounding the fences were based on engineering judgement, with the assumption that debris would accumulate along the fence line and significantly impact the conveyance across the fence line. Manning's n values for the areas of San Luis Obispo Creek, Prefumo Creek, and Froom Creek are based on values established in the Floodplain Evaluation Report for the previous phase of the Project (HDR 2023). The Manning's n value used for the area in the agricultural portion of the San Luis Ranch (described as "Ag Hoop Houses") was based on a floodplain value that considered obstructions and vegetation estimated following Cowan's procedure (USACE 2016). Table 4. Manning's n Values Description Manning's n Description Minor Stream - Clean, Winding, Asphalt 0.016 Some Rock 0.04 Minor Stream - Some Weeds and Open Water 0.03 Stones 0.04 Urban Area 0.04 Pasture - No Brush 0.025 Urban -Parking Lot Area 0.04 Pasture - Short Grass 0.03 Urban -Cemetery 0.04 Pasture - High Grass 0.04 Urban Planned Development 0.08 Cultivated Area - No Crop 0.03 Urban -Open Grass Areas 0.05 Cultivated Area - Mature Row Crop 0.035 Urban -Cemetery - Short Grass 0.035 Cultivated Area - Mature Field Crop 0.045 Brush - Scattered Brush, Heavy Chain link Fence 9 Weeds 0.05 SLO Creek — one-dimensional (1 D) Brush - Light Brush and Trees, in model 0.065 Summer 0.07 Prefumo Creek - 1 D model 0.07 Heavy Stands of Timber and Brush 0.1 Froom Creek - 1 D model 0.04 Asphalt - Smooth 0.013 Ag Hoop Houses 0.28 20 1 June 25, 2026 Page 692 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.2.4 Proposed Condition Geometry Adjustments The existing condition hydraulic model geometry was used as a basis for the proposed condition hydraulic model. The following adjustments were incorporated in the proposed condition geometry to represent the Project improvements. 4.2.4.1 Terrain The existing condition merged terrain described in Section 4.2.3 was used as the base terrain for the proposed condition terrain. Additional modifications were made to the base terrain using the data sources listed in Table 3 that were provided by Consor Engineers (numbers 7 and 8) to account for the proposed Project improvements. The grading for roadway approaches for the Project bridges and Elks Lane realignment were updated based on information provided by Consor Engineers (Consor Engineers 2025). The piers, abutments, and mechanically stabilized earth (MSE) walls that support the Project bridges (Figure 3, Figure 4, and Figure 5) were imported into the HEC-RAS hydraulic model based on information provided by Consor Engineers (Consor Engineers 2026e) and the elevations were modeled using terrain modifications to be above the 100-year WSE. See the top image in Figure 10 for an enlarged version of the existing condition merged terrain, which is zoomed in (as compared to the terrain in Figure 9 that shows the terrain within the model domain) to better discern the changes to the terrain in the proposed condition. The terrain in the areas beyond the visible areas in Figure 10 are the same in both the existing and proposed condition geometries. See the bottom image in Figure 10 for the proposed condition merged terrain. 4.2.4.2 Bridges The bridges included in the existing condition geometry remained the same in the proposed condition geometry (Figure 9). Elements of the Project bridges that would be within contact with the evaluated flows were modeled using terrain modifications to represent the piers, abutments, and MSE walls. The bridge superstructures would be elevated above the 100-year WSE and were not included in the model. 4.2.4.3 Manning's Roughness Coefficients The same values were used in both the existing and proposed conditions models except in the areas in the vicinity of the proposed Project bridges where the existing at -grade US 101 ramps and Prado Road subgrade would be removed. The Project is proposing landscaping in the areas where the subgrade will be removed, and the Manning's n values were set to 0.04 in the proposed condition. JunP Aq,'J pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 10.Terrain Comparison in Vicinity of Project Existing Terrain (top image) ' � .•_��•-d 'OG 2U'1S DUI Proposed Terrain (bottom image) y SN ,c 'FG_2025_1023_T.... r- 22 1 June 25, 2026 Page 694 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.3 Hydraulic Model Results As previously stated in Section 4.2.2, the hydraulic models were computed using constant flow values at the upstream boundaries and a normal depth at the downstream boundary. San Luis Obispo Creek flows in a southerly direction within the model domain. The model simulations were run for a period long enough for the model results to stabilize to a steady state, which was confirmed by result hydrographs from various locations throughout the model. The hydraulic model results are reported at the final timestep of the model simulations. The hydraulic model results are presented in this section as detailed maps of the 2D HEC-RAS results and as tables and graphs extracted from the 2D results using a profile along San Luis Obispo Creek (see Figure 11, which shows the profile line) and cross section lines (see locations of cut lines in Figure 12, which were cut along the upstream faces of the bridges). The profile line follows the channel alignment along San Luis Obispo Creek through the model domain. The downstream limit of the model domain is at approximately 0 ft and the upstream limit of the model domain is at approximately 17,500 ft measured along the profile line of San Luis Obispo Creek. These main channel distance measurements will be referred to as river stations (RS) in this study, and the RS decreases numerically in the downstream direction. For reference, a few geographical features in the Project vicinity and within the model domain are identified in Table 5. Table 5. River Stations along San Luis Obispo Creek at Geographical Locations 16,900 Intersection of Marsh Street and Archer Street 13,600 Madonna Road 8,360 Prado Road 2,150 Confluence with Prefumo Creek 1,765 Los Osos Valley Road 1,050 Confluence with Froom Creek The cross section lines were chosen to be parallel to the bridges and to represent the locations upstream of the bridges. References to the profile line and cross section lines are made in the following hydraulic model results summary in Section 4.3. Additional detailed hydraulic model results are available in Appendix B (showing the results within the extents of the model) and Appendix C (showing the results within the Project vicinity). June Ag5:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure 11. Location of Profile Used to Summarize Model Results LEGEND Proposed Project 2DW ft I I Sources: USACE 2024 and Consor Engineers 2026a (with 2D model boundary, San Luis Obispo Creek profile, and notes from HDR) 24 1 June 25, 2026 Page 696 of 1059 � p N Op �4 K O 0 CD 0 \ ti pr N 'o cn C ,r Jz c R� a ,- .z a+ n � a i r hr I - ` X `-� f? rf Page 697 of 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 4.3.1 Water Surface Elevations The results of the hydraulic models indicate that flows spill out of the banks of San Luis Obispo Creek upstream of the Project area until approximately RS 10,500 where the modeled flows are contained within the San Luis Obispo Creek channel. Prado Road is located approximately at RS 8,360. The spill flows occur in the 100-year and 50-year events and is an existing condition that is perpetuated in the proposed condition (see Figure 13, which shows the 100-year flow depths in the existing condition; Appendix B and Appendix C include additional results for the 50-year flow and for the proposed condition). Figure 14 shows the 100-year flow depths in the existing condition, which is a larger scale version of Figure 13 to show greater detail in the Project vicinity. As shown in Figure 14, the 100-year and 50-year flows are contained within San Luis Obispo Creek in the reach starting from RS 10,500 and downstream past Prado Road within the limits of the model domain. Figure 13. Existing Condition 100-year Flow Depths LEGEND Proposed PrniPrt 2D Model D San Luis Ot 0irnr200002:00M e14 2000 ft I I Sources: USACE 2024 and Consor Engineers 2026a (with 2D model boundary, San Luis Obispo Creek profile, depth raster, and notes from HDR) 26 1 June 25, 2026 Page 698 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project The water surface profiles along the San Luis Obispo Creek profile line are shown in Figure 15, which compares the 100-year water surface profiles in the existing and proposed condition, and Figure 16, which compares the 50-year water surface profiles in the existing and proposed condition. Figure 15 and Figure 16 show insignificant changes in WSEs along the San Luis Obispo Creek profile. Comparison rasters were also generated in HEC-RAS to calculate the difference in WSEs between the proposed and existing conditions. A comparison of the WSEs within the model domain are shown in Figure 17 for the 100-year and 50-year storm events. Figure 18 and Figure 19 show larger scale versions of Figure 17 to show greater detail in the Project vicinity. In general, the comparisons in WSEs show insignificant changes along San Luis Obispo Creek; the model shows increases in WSE that are 0.2 ft or less (or decreases in WSE) within the model domain. There are localized increases and decreases in WSE within the vicinity of the Project improvements. During the 100-year storm event, the maximum increase in the WSE is 2.4 ft, and it occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in WSE is 1.9 ft, and it also occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. WSEs were also extracted along the cross section lines shown in Figure 12 along the upstream faces of the bridges. The maximum WSEs along those lines are shown in Table 6 for the 100-year storm and Table 7 for the 50-year storm. Based on a comparison of the WSEs extracted along the respective cross section lines, the maximum WSE in the proposed condition compared with the maximum WSE in the existing condition increases by 0.1 ft or less. The average WSEs along those lines are also shown in Table 6 for the 100-year storm and Table 7 for the 50-year storm. Based on a comparison of the WSEs extracted along the respective cross section lines, the average WSE in the proposed condition compared with the average WSE in the existing condition increases by 0.3 ft or less. JunPAg92pf 1059 _M C CD m x rh to ♦ I O Q CD p1 CO G v (D U) a) T o, (D 0 0 I C -u Ct)io O N N N W O_ p O ca ;U(D Op N O Q O 7 � fD 7 7 N (n C O O � n `< Page 700 of 1059 0 -0 U) CD fl_ O O CD CD v m I v � o cD o 0 o N O O O 0 O O 8 0 O O a Elevation (ft NAVD 88) CO O N Ca CD Cr 6) O O O O O O O O v O O O C c� O_ N � v ao nQ o X m 0 0 v COD � cQ m � �Q m m _. o cn c T %J IV Page 701 of 1059 00 O O O O � O (D N 7� I W O O O m x 0 n 00 0 CD v o v 73 73 CD U m (1)' v � o IcD o 0 0 0 0 0 m CL N Cl O O O G O CD ffCl G m 0 0 0 8 0 O O Elevation (ft NAVD 88) CO O N W Cr 8 O O O O O O O O v O O O C -u Ct)io 03 v N N W O_ p_ O O 17 m Op N O Q O 7 � fD 7 N O' 7 N cc c (D C.) (D CL Page 702 of 1059 W I0 CD DO m n 0 3 v c 0 a 8 Cn CD U) m n 0 \\ -0 v cn ti cn 0 D `> �boo� S 8 c Cl)� 03 m � v W nQ o o m v 0 ny � cQ m � MQ m m n o 0 m c �< T V IV Page 703 of 1059 Cn O C 0 CD C CD D (7 m N O N A N 7 Q (7 O 1 cn O m 12. CD CD N CY Cn N 7 r y 0 k � 0 C- } CD CD .T r O, TI C -u c C o3 CD w m 90 W Q p � o ca O 17 m `o Q o CD � � 2 in cQ c m n 0 O m n P Page 704 of 1059 Aj Page 705 of 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 6. 100-year Water Surface Elevations Upstream of Bridges WSE (ft NA VD 88) Change in WSE (ft NA VD 88) Change in WSE (ft) WSE (ft) Existing Proposed (Proposed Existing Proposed (Proposed -Existing) -Existing) Prado Road West 136.9 136.9 0 133.7 133.9 0.2 Overcrossing Prado Road East 137.3 137.4 0.1 137.3 137.4 0.1 Overcrossing ■ US 101 NB Off -Ramp 136.8 136.5 -0.3 136.3 136.2 -0.1 US 101 NB On -Ramp 137.5 137.E � 137.4 137.5 0.1 Table 7. 50-year Water Surface Elevations Upstream of Bridges WSE (ft NA VD 88) Change in WSE (ft NA VD 88) Change in WSE (ft) WSE (ft) Existing Proposed (Proposed Existing Proposed (Proposed -Existing) -Existing) Prado Road West 136.6 136.7 0.1 133.2 133.5 0.3 Overcrossing Prado Road East 136.9 136.9 0 136.9 136.9 0 Overcrossing US 101 NB Off -Ramp 136.5 136.2 -0.3 136.1 135.9 -0.2 US 101 NB On -Ramp 137.0 137.1 0.1 137.0 137.0 0 According to Memo to Designers 16-1 (Caltrans 2017), a hydrologic summary table shall be placed on the Project Foundation Plan. The hydrologic summary is shown in Table 8 for the proposed Prado Road west overcrossing, Table 9 for the proposed Prado Road east overcrossing, Table 10 for the proposed US 101 NB off -ramp to Prado Road, and Table 11 for the proposed US 101 NB on -ramp from Prado Road. The reported WSEs are based on the upstream cross section at the proposed respective bridges. The WSE varies along the cross sections, and the reported value is the maximum at each of the bridge locations. 34 1 June 25, 2026 Page 706 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Table 8. Hydrologic Summary Table for Prado Road West Overcrossing Discharge 2,330 3,470 4,510 Water Surface Elevation at 136.7 136.9 137.2 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. Table 9. Hydrologic Summary Table for Prado Road East Overcrossing Frequency ii Discharge 1,600 2,610 3,630 Water Surface Elevation at 136.9 137.4 137.8 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. Table 10. Hydrologic Summary Table for US 101 NB Off -Ramp Hydrologic 50-year 100-year Vischarge,.00 Water Surface Elevation at 136.2 136.5 136.7 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. JunpAgg2zq739f 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 11. Hydrologic Summary Table for US 101 NB On -Ramp Discharge 1,600 2,610 3,630 Water Surface Elevation at 137.1 137.6 138.1 Bridge Floodplain data are based upon information available when the plans were prepared and are shown to meet federal requirements. The accuracy of said information is not warranted by the state and interested or affected parties should make their own investigation. 4.3.2 Freeboard As described in Section 1.4, the hydraulic design criteria applicable to the Project require that bridges pass the 100-year design flow without freeboard and the 50-year flow with 2 ft of freeboard from the lowest portion of the bridge span. The WSEs and available freeboard are presented in Table 12 for the 100-year storm and Table 13 for the 50-year storm. The minimum soffit elevations are based on the bridge general plans (Consor Engineers 2026b, 2026c, and 2026d). The soffit elevations account for the depth of the proposed girders but do not incorporate the roadway cross slope. Based on the results of the hydraulic modeling, the bridges would provide applicable freeboard during the 100- year and 50-year flows. Table 12. 100-Year Water Surface Elevations and Freeboard Prado Road West Overcrossing 142.7 Prado Road East Overcrossing 139.4 US 101 NB Off -Ramp 144.4 US 101 NB On -Ramp 144.4 136.9 137.4 I 136.5 137.6 Table 13. 50-Year Water Surface Elevations and Freeboard Prado Road West Overcrossing 142.71 Prado Road East Overcrossing 139.37 US 101 NB Off -Ramp 144.42 US 101 NB On -Ramp 144.42 136.7 136.9 136.2 137.1 5.8 7.9 M MMI 2.5 8.2 7.3 36 1 June 25, 2026 Page 708 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 4.3.3 Flow Velocities Comparison rasters were generated in HEC-RAS to calculate the difference in velocities between the proposed and existing conditions. A comparison of the velocities within the model domain are shown in Figure 20 for the 100-year and 50-year storm events. Figure 21 and Figure 22 show larger scale versions of Figure 20 to show greater detail in the Project vicinity. In general, the comparisons in velocities show insignificant changes along San Luis Obispo Creek; the model shows the increases in velocities are 0.2 ft per second (ft/s) or less (or that there are decreases in velocities) within the model domain. There are localized increases in velocities within the vicinity of the Project improvements. During the 100-year storm event, the maximum increase in velocity is 4.9 ft/s, and it occurs at the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in velocity is 4.7 ft/s, and it also occurs at the western abutment (Abut 1) at the Prado Road west overcrossing bridge. Junp 2zq%pf 1059 C Z CD N 0 0 su y C n cn �D 7 S �D N v 0 CL v 0 3 sv C cn N 03 v N N W O_ p_ O 17 m Op N O Q O 7 � fD 7 D v cc S. (C.) o � (D n Page 710 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Figure 21. 100-year Velocity Comparison (Proposed - Existing) within Project Vicinity v.���' •• �SBbtf!/:'C�MlVN OI00� � V , 01JAN200000 M A /1 6 ,rj J 1 isit rl 1 ox rx Sources: USACE 2024 and Consor Engineers 2026a (with San Luis Obispo Creek profile, and velocity raster from HDR) Figure 22. 50-year Velocity Comparison (Proposed - Existing) within Project Vicinity Nk ' sa«lm- ca.P.�va oso o1JANwaaamoa M- al — oca coo Sources: USACE 2024 and Consor Engineers 2026a (with San Luis Obispo Creek profile, and velocity raster from HDR) Junp2Z1113pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 5 Scour Analysis HDR evaluated bridge scour per the criteria described in "Evaluating Scour at Bridges" (FHWA 2012). HDR evaluated the scour potential using the results of the proposed condition 2D hydraulic model analysis from HEC-RAS for the 100-year design storm as the scour design flood and the 200-year design storm as the scour (design) check flood (see Section 4.3 for the hydraulic model results) and the soil properties at the Project site from the geotechnical studies (see Section 5.2 for a summary of the existing channel bed characteristics). The calculations were performed for the Project bridges (US 101 NB off - ramp to Prado Road, US 101 NB on -ramp from Prado Road, and the Prado Road overcrossing) that will be located within the San Luis Obispo Creek floodplain. The Prado Road west and east overcrossing structures comprise the Prado Road overcrossing. The US 101 NB off -ramp and US 101 NB on -ramp intersect Prado Road in the area between the west and east overcrossing structures. The abutments in the area of the intersection of Prado Road with the US 101 off- and on -ramps are enclosed by MSE walls. The abutment scour equations were used to estimate the scour at the MSE walls (Table 14). Table 14. Summary of Structures within Floodplain and Type of Scour Assessed Prado Road West Abut 1 (at BB end) NCHRP abutment Overcrossing Bent 2 L_.M Bent 3 Pier Abut 4 (at EB end) NCHRP abutment (enclosed by MSE Wall) Prado Road East Abut 1 (at BB end) NCHRP abutment Overcrossing (enclosed by MSE Wall) Bent 2 Pier - Abut 3 (at EB end) NCHRP abutment US 101 NB Off -Ramp to Abut 1 (at BB end) NCHRP abutment Prado Road Bent 2 Pier Abut 3 (at EB end) NCHRP abutment (enclosed by MSE Wall) US 101 NB On -Ramp from Abut 1 (at BB end) NCHRP abutment Prado Road (enclosed by MSE Wall) Bent 2 Pier Abut 3 (at EB end) NCHRP abutment The following sub -sections summarize the results of the scour analysis. 5.1 Caltrans Bridge Inspection Reports Bridge Inspection Reports do not exist because the Project is proposing new structures. 40 1 June 25, 2026 Page 712 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 5.2 Existing Channel Bed Under the existing conditions, the locations of the proposed structures are currently impervious. As part of the Project, the pavement subgrade will be removed, and will be pervious, which would be susceptible to scour. According to the Draft Structure Preliminary Geotechnical Report Bridges for the Project (Yeh and Associates, Inc. 2025), the regional geology at the proposed Project bridges is young alluvial floodplain deposits. The Draft Structure Preliminary Geotechnical Report Bridges also describes the subsurface conditions at the Project, which were based on cone penetration tests (CPT) soundings, which showed surficial units of existing artificial fill and alluvium (Qya); in the area of the proposed Project bridges, the ground surface underlying the existing fill was predominantly younger alluvium (Qya) with the Qyal subunit generally in the upper zone compared to the Qya2 subunit (Yeh and Associates, Inc. 2025). The Qyal subunit consisted of "predominantly soft to hard clay and sandy clay..." and the Qya2 subunit consisted of "predominantly soft to medium stiff clay..." (Yeh and Associates, Inc. 2025). Based on borings in the vicinity of the Project bridges, the soil classifications at the proposed supports are flat clay (CH) and lean clay (CL). Based on these soil classifications, the channel bed in the floodplain areas underlying the proposed foundations was considered to be cohesive for the purpose of analyzing scour. 5.3 Long -Term Bed Elevation Change Long-term bed elevation changes (degradation) are typically based on historical data at the bridge site. As previously stated in Section 5.1, Bridge Inspection Reports do not exist at the Project, and long-term bed elevation change was not assessed at the Project. 5.4 Contraction Scour Contraction scour occurs when the flow area of a stream is reduced by: 1) the natural contraction of the stream channel; 2) a bridge structure; 3) the overbank flow forced back to the channel, 4) natural stream constrictions, or 5) long highway approaches to the bridge over the floodplain. From the continuity equation, a decrease in flow area results in an increase in average velocity and bed shear stress through the contraction. Hence, there is an increase in erosive forces in the contraction section, and more bed material is removed from the contracted reach than is transported into the reach. This increase in transport of bed material from the reach lowers the natural bed elevation. As the bed elevation is lowered, the flow area increases. Thus, the velocity and shear stress decrease until relative equilibrium is reached (i.e., the quantity of bed material that is transported into the reach is equal to that removed from the reach, or the bed shear stress is decreased to a value such that no sediment is transported out of the reach). Contraction scour, in a natural channel or at a bridge crossing, involves removal of material from the bed across all or most of the channel width (FHWA 2012). There are two conditions for contraction scour: clear -water or live -bed. Clear -water contraction scour occurs when the bed material is not in motion in the flow upstream of the bridge crossing. Clear -water conditions are typical in floodplain overbank areas such as at the Project site. JunP2Z113t-pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project As previously stated in Section 5.2, the channel bed in the floodplain was considered to be cohesive for the purpose of analyzing scour. Equation 6.6 from HEC-18 was used to calculate contraction scour for cohesive materials for the bridge supports (FHWA 2012). A summary of the calculated contraction scour depths is included in Table 15 and the detailed calculations are included in Appendix D. Table 15. Calculated Contraction Scour Depths Structure Name m i Contraction Scour Depth ii ii Flood)(Scour Design (Scoul; ll ..• Prado Road West Abut 1 (at BB end) 1.7 - Overcrossing Bent 2 1.4 ■ Bent 3 0.9 Abut 4 (at EB end) 1.2 . (enclosed by MSE Wall) Prado Road East Abut 1 (at BB end) 1 2 Overcrossing (enclosed by MSE Wall) Bent 2 0.8 1.� Abut 3 (at EB end) 0.7 1 US 101 NB Off -Ramp Abut 1 (at BB end) 1.1 1. to Prado Road Bent 2 1.1 1.3 Abut 3 (at EB end) 1.2 1.2 (enclosed by MSE Wall) US 101 NB On -Ramp Abut 1 (at BB end) from Prado Road (enclosed by MSE Wall) 1.2 1.2 Bent 2 0 0.0 Abut 3 (at EB end) 0.9 1.3 5.5 Pier Scour Pier scour is caused by vortices (known as a horseshoe vortex) forming at the base of the pier. The horseshoe vortex results from the pileup of water on the upstream surface of the pier and subsequent acceleration of the flow around the base of the pier. The scour depth at a pier is influenced by pier design (shape and dimension), flow characteristics (flow rate, local velocity, and depth at the pier), and sediment particle size distribution. As previously stated in Section 5.2, the channel bed in the floodplain was considered to be cohesive for the purpose of analyzing scour. Equation 7.35 from HEC- 42 1 June 25, 2026 Page 714 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 18 was used to calculate pier scour for cohesive materials (FHWA 2012). The pier scour calculation assumes the footings will not be exposed to flow. A summary of the calculated local pier scour depths is included in Table 16 and the detailed calculations are included in Appendix D. Table 16. Calculated Local Pier Scour Depths Prado Road West Overcrossing Prado Road East Overcrossing US 101 NB Off -Ramp to Prado Road US 101 NB On -Ramp from Prado Road Bent 2 5.9 6.7 Bent 2 Bent 2 Bent 2 5.6 Abutment Scour 4.7 5.9 Mon"Empp- all 2.7 Abutment scour occurs when the bridge abutments and roadway embankments block approaching flow. A vortex is formed at the upstream end of the abutment and along the toe of the abutment due to the flow obstruction caused by the abutments. The highly turbulent flow caused by the abutments generates the erosive shear action and subsequently causes scouring. According to HEC-18 (FHWA, 2012), local scour at bridge abutments is commonly evaluated using either the Froehlich or HIRE live -bed scour equations. The National Cooperative Highway Research Program (NCHRP) developed alternative abutment scour equations based on a range of abutment types, locations, flow conditions, and sediment transport conditions. While the Froehlich, HIRE, and NCHRP equations are acceptable methods that can be used to estimate scour at abutments, the NCHRP equations have several advantages. Unlike the Froehlich and HIRE equations, the NCHRP equations do not use an effective embankment length, which can be difficult to determine. The NCHRP equations are also considered to be more representative of the physical scouring processes at the abutments. Because of these reasons, the NCHRP method was used to estimate scour at the abutments. The NCHRP method calculates a scour depth that includes both local and contraction scour components at the abutment. The NCHRP scour was calculated using the equations presented in Section 8.6.3 of HEC-18 (FHWA 2012). The contraction scour depth calculated in Section 5.4 of this report was subtracted from the calculated scour depth to determine the local abutment scour. Some of the abutments are proposed to be enclosed by MSE walls, and the NCHRP equation was also used to estimate the local scour at the MSE walls. A summary of the calculated local scour depths for the abutments and MSE walls is included in Table 17 and the detailed calculations are included in Appendix D. JunPAgg2Z115t:pf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 17. Calculated Local Abutment (and MSE Wall) Scour Depths Prado Road West Abut 1 (at BB end) li� Overcrossing Abut 4 (at EB end) MOE MM (enclosed by MSE Wall) Prado Road East Overcrossing Abut 1 BB end) (enclosed by MSE Wall) 1 Abut 3 (at EB end) 1.= 2.9 US 101 NB Off -Ramp Abut 1 (at BB end) 4.8 to Prado Road Abut 3 (at EB end) 1.4 2.1 (enclosed by MSE Wall) US 101 NB On -Ramp Abut 1 (at BB end) 1.7 2.8 from Prado Road (enclosed by MSE Wall) Abut 3 (at EB end) 5.6 7.7 5.7 Total Scour Total scour is the sum of the long-term bed elevation change (degradation scour), contraction scour, and local scour (see Table 18 through Table 21 for the scour depths for the proposed bridges based on the scour design flood estimates). Table 18. Scour Summary Table: Prado Road West Overcrossing Abut 1 N/A 1.7 6.2 Bent 2 N/A 1.4 5.9 Bent 3 N/A 0.9 11.0 Abut 4 N/A 1.2 1.7 Table 19. Scour Summary Table: Prado Road East Overcrossing Abut 1 N/A 1.2 1.4 Bent 2 N/A 0.8 4.7 Abut 3 N/A 0.7 1.6 44 1 June 25, 2026 Page 716 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Table 20. Scour Summary Table: US 101 NB Off -Ramp Abut 1 N/A 1.1 4.8 Bent 2 Abut 3 N/A 1.2 1.4 Table 21. Scour Summary Table: US 101 NB On -Ramp Abut 1 N/A 1.2 1.7 Bent 2 N/A 0.0 I Abut 3 N/A 0.9 5.6 According to Memo to Designers 16-1 (Caltrans 2017), a scour data table shall be placed on the Project Foundation Plan. The scour data tables (see Table 22 through Table 25) for the Project present the long-term scour elevations (based upon the long-term bed degradation and contraction scour depths) and the short-term scour depths (based upon the local scour depth). The long-term scour elevations reference the finish grade elevations at the supports. Table 22. Scour Data Table: Prado Road West Overcrossing Abut 1 127.8 6.2 Bent 2 127.2 5.9 Bent 3 130.9 11.0 131.8 1.7 Table 23. Scour Data Table: Prado Road East Overcrossing Abut 1 131.8 1.4 Bent 2 132.2 4.7 Abut 3 132.3 1.6 JunP2711749f 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Table 24. Scour Data Table: US 101 NB Off -Ramp Abut 1 131.9 4.8 1r3ent 2 11M 5.6 Abut 3 131.8 1.4 Table 25. Scour Data Table: US 101 NB On -Ramp Abut 1 131.8 1.7 �i3.0 2.0 Abut 3 132.1 5.6 46 1 June 25, 2026 Page 718 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project 6 References California Department of Transportation (Caltrans) 2014 Design Information Bulletin No 87-01. (DIB 87-01). "Hybrid Streambank Revetments: Vegetated Rock Slope Protection." Accessed February 4, 2026. https://dot.ca.gov/- /media/dot-media/programs/design/documents/dib87-01.pdf. 2017 Memo to Designers 16-1 Hydraulic Design for Structures over Waterways. Accessed February 4, 2026. htti)s://dot.ca.gov/-/media/dot- media/programs/engineering/documents/memotodesigner/f0006651-mtd-16-1-final.pdf. 2019 California Amendments to the AASHTO LRFD Bridge Design Specifications (2017 Eighth Edition). Accessed February 4, 2026. https://dot.ca.gov/programs/engineering- services/manuals/aashto-Irfd-ca-amendments. 2025a "Chapter 820: Cross Drainage" in Highway Design Manual. Accessed February 16, 2026. https://dot.ca.gov/-/med ia/dot-media/programs/design/documents/chp0820--a l l ypdf. 2025b Bridge Design Memo 10.7. 10.7 Piles and Shafts." Accessed October 30, 2025. https://dot.ca.gov/-/media/dot- media/programs/engineering/documents/brid edq�esignmemos/10/202506bdml007pilesa ndshafts-al 1 y.pdf. 2025c Structure Technical Policy 2.6. "2.6 Hydraulic Design for Structures over Waterways." Accessed June 8, 2026. https://dot.ca.gov/-/media/dot- med is/programs/engi neering/documents/structure-technical-policy/section-2/sto-26- hydraulic-design-for-structures-over-waterways-121025-a11 y.pdf. Chow, V.T. 1959 Open -Channel Hydraulics. New York: McGraw-Hill Book Co. City of San Luis Obispo Department of Public Works and County of San Luis Obispo Flood Control District — Zone 9 2003 Drainage Design Manual. Volume III. Accessed February 4, 2026. htti)s://www.slocity.org/home/showr)ublisheddocument/4400/638121531708370000. Consor Engineers 2025 Prado IC_Surfaces for HDR_20251023.dwg. [Project grading for approaches and Elks Lane] 2026a Prado Plan.dwg [Proposed roadway linework] 2026b D218721a-a-gp01-General Plan.pdf. [Prado Overcrossing Bridge General Plan] 2026c D218721b-a-gp01-OFF-Ramp GP.pdf. [US 101 NB Off -Ramp Bridge General Plan] 2026d D218721c-a-gp01-ON-Ramp GP.pdf. [US 101 NB On -Ramp Bridge General Plan] 2026e D218721—BRIDGE-PLAN.dwg. [Project linework for abutments, MSE walls, and piers] Federal Emergency Management Agency (FEMA) 2024 Flood Insurance Study. San Luis Obispo County, California and Incorporated Areas. Flood Insurance Study Number 06079CV001 D. Version Number 2.6.3.6. Effective Date: June 6, 2024. Accessed February 4, 2026. https://msc.fema.gov/portal/downloadProduct?productTyl)elD=FINAL PRODUCT&produ ctSubTypelD=FIS REPORT&productlD=06079CV001 D. Federal Highway Administration (FHWA) 2012 "Evaluating Scour at Bridges." Hydraulic Engineering Circular No. 18. Fifth Edition. Publication No. FHWA-HIF-12-03. JunP2Z119tpf 1059 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project 2026 Title 23 Chapter I Subchapter G Part 650. "Bridges, Structures, and Hydraulics" Subpart A Section 650.115. Accessed February 16, 2026. https://www.ecfr.gov/current/title- 23/chapter-1/subchapter-G/part-650. Google Earth 2025 Google Earth Pro 7.3.6.10441. Gotvald, A.J., N.A. Barth, A.G. Veilleux, and C. Parrett 2012 Methods for determining magnitude and frequency of floods in California, based on data through water year 2006. United States Geological Survey Scientific Investigations Report 2012-5113. Accessed January 8, 2026. http://pubs.usgs.gov/sir/2012/5113. HDR 2019a 2-Dimensional Hydraulic Model Update Draft Report. 2019b EC_wP8_08.02.2019.tif. [Existing condition terrain used in development of 2- Dimensional Hydraulic Model Update Draft Report] 2023 Floodplain Evaluation Report. Prado Road Overcrossing Project On U.S. 101 05-SLO- 101-PM 26.5-27.3. San Luis Obispo County Department of Public Works 2014 SLO County Watersheds. (Computer file). Accessed July 20, 2023. https://www.slocounty.ca.gov/Departments/Public-Works/Forms- Documents/Projects/SLO-Watershed-Project/Resources/SLO-Cou nty-Watersheds- 1 .as x. 2022 Public Improvement Standards. Accessed February 4, 2026. https://www.slocounty.ca.gov/departments/public-works/forms-documents/development- services/public-improvements/public-improvement-standards/countypublic- i m p rove m e n t-standards-2022. United States Army Corps of Engineers (USACE) 2016 HEC-RAS River Analysis System, Hydraulic Reference Manual, Version 5.0. CPD-69. 2024 Hydrologic Engineering Center's River Analysis System (HEC-RAS) [Modeling software] Version 6.6. Accessed February 4, 2026. https://github.com/HydrologicEngineeringCenter/hec- downloads/releases/download/l .0.33/HEC-RAS_66_Setup.exe. United States Geological Survey (USGS) 2019 "CA AZ FEMA R9 2017 D18 Airborne Lidar Report." Contract # G16PC00022. Task Order # 140G0218F0027. Contractor Woolpert. Project # 78262. Accessed February 6, 2026. https://prd- tnm.s3.amazonaws.com/StagedProducts/Elevation/metadata/CA AZ FEMA R9 Lidar 2017 D18/CA FEMA Z4 B2 2018/reports/CA AZ FEMA R9 Lidar 2017 D18 Lidar ProjectReport.pdf. 2018 "USGS Original Project Resolution CA_AZ_FEMA_R9—Lidar_2017_D18 60521606." Accessed February 6, 2026. https://www.sciencebase.gov/catalog/item/60491 clfd34ebl20311 ac439. 2026a StreamStats. Accessed February 4, 2026. https://streamstats.usgs.gov/ss/. 2026b National Hydrography Dataset. Accessed February 11, 2026. httr)s://www.usgs.gov/national-hvdrographv/national-hvdrographv-dataset. 48 1 June 25, 2026 Page 720 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Wallace Group 2025a 0061-0077 DSGN-Creek Grading.dwg. [San Luis Obispo Creek surface associated with the separate proposed bridge replacement at Existing Bridge Number 49C01071. 2025b 5-1H640 US 101 and Prado Road - TOPO.dwg. [Project topography based on aerial mapping with survey conforms]. 2025c 5-1H640 US 101 and Prado Road - TOPO_091525.dwg. [Topography with newly added digital terrain model in the farm/agricultural portion of the San Luis Ranch southwest of the intersection of US 101 with Prado Road]. Yeh and Associates, Inc. 2025 Draft Structure Preliminary Geotechnical Report Bridges. US 101 and Prado Road Interchange Project. San Luis Obispo, California. 05-SLO-101-PM 26.5-27.3. Caltrans Project No. 113-0000-0405; EA 05-1 H640. City Specification No. 2091613-02. Yeh Project No.: 223-400. JunP 2Z�14pf 1059 Page 722 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Appendix A. FIS Excerpts PAgp27202pf 1059 FLOOD INSURANCE STUDY VOLUME 1 OF 4 SAN LUIS OBISPO COUNTY, CALIFORNIA AND INCORPORATED AREAS L7 MMUNITY NAME COMMUNITY UMBER ARROYO GRANDE, CITY OF 060305 ATASCADERO, CITY OF 060700 EL PASO DE ROBLES, CITY OF 060308 GROVER BEACH, CITY OF 060306 _MORRO BAY, CITY OF _PISMO BEACH, CITY OF SAN LUIS OBISPO, CITY OF SAN LUIS OBISPO COUNTY, UNINCORPORATED AREAS FEMA REVISED: JUNE 6, 2024 FLOOD INSURANCE STUDY NUMBER 06079CV001 D Version Number 2.6.3.6 060307 060309 060310 060304 Page 724 of 1059 U) U) U) -0 0-0 -0 0-0 C)-0 -0 -0 -u 0000000000 � CD CD CD 3 o 0 o (D a (D (D (D �D s (D �3 0 m c�', �� m �� 3 3 m m m m m 0 cn cn cn 3 0 0 C7 su v v 0 0 0 X X X n n C� C� 0 0 0 m m (° CD CD CD CD CD v 7 Co 77, •< •< CD CD CD CD CD CD Cn 0 CD 77 o 0 Co XD 00 C �]D D CCC CC0 2 D D D;U D D D D C,/D v 0 0 0 0 cr0-0 0 --0 - o (Q•CD-0 v g �g CTC� v-0CD n C c CDg m �--� C -C X 0< CD m CD m C/) _0 c �� c o o 0 wcn c CD 0 �� n� cn nCD M �' °' < �' 3 0 �� <_ �, CD CD (i] m (D 3 3 0 __ O 3 N- 0 CU 0) ? 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HEC-RAS Model Results: Grid Figure B 1. Figure B 2. Figure B 3. Figure B 4. Figure B 5. Figure B 6. Figure B 7. Figure B 8. Extents View Depth (ft) at 100-year Flow Depth (ft) at 50-year Flow Velocity (ft/s) at 100-year Flow Velocity (ft/s) at 50-year Flow Water Surface Elevation (ft NAVD 88) at 100-year Flow Water Surface Elevation (ft NAVD 88) at 50-year Flow Comparison of Velocity and Water Surface Elevation at 100-year Flow Comparison of Velocity and Water Surface Elevation at 50-year Flow June 25, 2026 Page 728 of 1059 Page 729 of 1059 Page 730 of 1059 � x a= o 7w �o J O to CD a 0 0 r a t � t � 1 Page 731 of 1059 — --� k y 7e \ � : . � \ § � �\ . > �-■ —� § k � � a , 2 � w h ~�� �\ ! „■ ��� � - � ■ Page 732 0 1059 Page 733 of 1059 Page 734 of 1059 `° \ Q. \, \ ci O 0 8 R o Y i �L�o4 �aSi Z � g � � N e !" m m < x \ z 00 r °D o 3 ?. Y O g 2 � g V 2) Page 735 of 1059 g �p44�z F;ISR�f;tl O v v c 8 cn C a� tS 1 < e Y Z N8 pO pO � 8 Page 736 of 1059 Preliminary Bridge Design Hydraulic Study ��� US 101 at Prado Road Interchange Project Appendix C. HEC-RAS Model Results: Project Vicinity View Figure C 1. Depth (ft) at 100-year Flow Figure C 2. Depth (ft) at 50-year Flow Figure C 3. Velocity (ft/s) at 100-year Flow Figure C 4. Velocity (ft/s) at 50-year Flow Figure C 5. Water Surface Elevation (ft NAVD 88) at 100-year Flow Figure C 6. Water Surface Elevation (ft NAVD 88) at 50-year Flow Figure C 7. Comparison of Velocity and Water Surface Elevation at 100-year Flow Figure C 8. Comparison of Velocity and Water Surface Elevation at 50-year Flow Figure C 9. Proposed Condition Depth (ft) at 200-year Flow Figure C 10. Proposed Condition Velocity (ft/s) at 200-year Flow PAgp273d2pf 1059 Preliminary Bridge Design Hydraulic Study F�� US 101 at Prado Road Interchange Project r Figure C-1. Depth (ft) at 100-year Flow Existing Condition wr � 7 . - &_ • Proposed Condition Y I a + 17 �- f., • 1P or. Page 738 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-2. Depth (ft) at 50-year Flow Existing Condition Jf srwr•f arsr�s►yrrflM.m-nw - - er.u�Y�aaommur t � r r , ff t C 4 - Proposed Condition •/s - - sr«W 'nmpyrps f•YfLY.m.upr ' _ OlNrnmom-mm �~t• �� m, ` ' f ems i Page 739 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project r Figure C-3. Velocity (ft/s) at 100-year Flow Existing Condition s«.,�r �.�•.,.y �m �r,r�r.m vrry i� �tJ A ' / Proposed Condition NM,w •wnpwj p►TMrfWrm-Wq� Page 740 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-4. Velocity (ft/s) at 50-year Flow Existing Condition k Proposed Condition P ;_ r- i June 25, 2026 Page 741 of 1059 Figure C-5. Water Surface Elevation (ft NAVD 88) at 100-year Flow Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project r Existing Condition ar.ewrt..�.yimr•.rrr.m wsr t Proposed Condition Page 742 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-6. Water Surface Elevation (ft NAVD 88) at 50-year Flow Existing Condition e.rcw t.wwwr•..ttr.r-ve ouJuomommm ` N u i >m Proposed Condition � HMSIMTivprW 50 �.r tIM.O WiF' OrJA10Om W-0000 t I >v ve . r .r z ,u '• Page 743 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study F�� US 101 at Prado Road Interchange Project r Figure C-7. Comparison of Velocity and Water Surface Elevation at 100-year Flow Velocity fts) Comparison A J Water Surface Elevation (ft NAVD 88) Comparison T -- ou�room m-aom Page 744 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Figure C-8. Comparison of Velocity and Water Surface Elevation at 50-year Flow Velocity fts) Comparison A •' W-1, I Water Surface Elevation (ft NAVD 88) Comparison I ` i x I' �\ 4 Page 745 of 1059 June 25, 2026 Figure C-9. Proposed Condition Depth (ft) at 200-year Flow Preliminary Bridge Design Hydraulic Study L�� US 101 at Prado Road Interchange Project r Figure C-10. Proposed Condition Velocity (ft/s) at 200-year Flow Page 746 of 1059 June 25, 2026 Preliminary Bridge Design Hydraulic Study US 101 at Prado Road Interchange Project Appendix D. Scour Calculations June 25, 2026 Page 747 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) Structure Name Support Contraction Scour Depth (ft) 200-year 100-year Prado Road West Overcrossing Abut 1(at BB end) 2.1 1.7 Bent 2 1.7 1.4 Bent 3 1.4 0.9 Abut 4 (at EB end) (enclosed by MSE Wall) 1.2 1.2 Prado Road East Overcrossing Abut 1(at BB end) (enclosed by MSE Wall) 1.2 1.2 Bent 2 1.1 0.8 Abut 3 (at EB end) 1.0 0.7 US 101 NB Off -Ramp to Prado Road Abut 1(at BB end) 1.3 1.1 Bent 2 1.3 1.1 Abut 3 (at EB end) (enclosed by MSE Wall) 1.2 1.2 US 101 NB On -Ramp From Prado Road Abut 1(at BB end) (enclosed by MSE Wall) 1.2 1.2 Bent 2 0.0 0.0 Abut 3 (at EB end) 1.3 0.9 Structure Name Support Local Scour Depth (ft) 200-year 100-year Prado Road West Overcrossing Abut 1(at BB end) 7.8 6.2 Bent 2 6.7 5.9 Bent 3 13.0 11.0 Abut 4 (at EB end) (enclosed by MSE Wall) 2.8 1.7 Prado Road East Overcrossing Abut 1(at BB end) (enclosed by MSE Wall) 2.1 1.4 Bent 2 5.9 4.7 Abut 3 (at EB end) 2.9 1.6 US 101 NB Off -Ramp to Prado Road Abut 1(at BB end) 5.8 4.8 Bent 2 6.4 5.6 Abut 3 (at EB end) (enclosed by MSE Wall) 2.1 1.4 US 101 NB On -Ramp from Prado Road Abut 1(at BB end) (enclosed by MSE Wall) 2.8 1.7 Bent 2 2.7 2.0 Abut 3 (at EB end) 7.7 5.6 Page 748 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) 100-year Scour Sum maryTables Scour Data Tables Prado West Overcrossing, Bridge No. 49C#### Prado West Overcrossing, Bridge No. 49C#### Short Term (Local)a MMMM Long Term (Degradation andShort Term ft) Scour Depth (ft) Contraction) lft) ur Elevation Scour Der Bent 3 1 Bent 3 130.91 Prado East Overcrossing, Bridge No. 49C#### Prado East Overcrossing, Bridge No. 49C#### Support Degradation M No. Scour Depth (ft) Scour Depth (ft) Short Term Contraction) (Sftj ur Elevation Scour Der a Bent 2 N/A 1 Abut 3 N/A 1 US 101 NB • • Bridge No.49 #### US 101• 1 Bridge No. Short Term (Local)Short EMMM Term ft) Scour Depth (ft) No. Contraction) (Sftj ur Elevation Scour Der Abut 1 1 Abut US 101 NB • • Bridge No. 49 #### US 101: • • Bridge No. 49 Support Degradation Contraction Short Term (Local) No. Scour Depth (ft) Scour Depth (ft) Scour Depth (ft) Support Long Term (Degradation and Short Term No. Contraction) (Sftj ur Elevation Scour Der Bent 2 N/A 0.0 2.0 Bent 2 133.0 2.0 Abut 3 N/A 0.9 Page 749 of 1059 US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge Prado Road West Overcrossing Support Abut 1 Bent 2 Bent 3 Equation 6.7: a = YV2n�2 Yo-1/3 I( KU Variable Value Unit Description g 62.4 62.4 62.4 Ib/ftA3 unit weight of water (62.4 Ib/ftA3 and 9800 N/mA3) VZ 4.3 3.6 2.9 ft/s average velocity in contracted section n 0.04 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.2 2.2 1.5 ft Upstream flow depth is 1.3 1.3 1.3 N/mA2=Pa lCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (�3VZ " p Ys-.It = 0.94y1 - / 9Y1 1 3 gny Variable Value Unit Description y1 0.7 0.7 0.5 m Upstream average flow depth Vz 1.3 1.1 0.9 m/s Average velocity in contracted section K, 1 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 1000 kg/mA3 Density of water g 9.81 9.81 9.81 m/sA2 acceleration due to gravity y, pit 0.5 0.4 0.3 m Ultimate contraction scour ys pit 1.7 1 1.4 1 0.9 Ift JUltimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 1 Page 750 of 1059 1=37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge Prado Road East Overcrossing Support Bent 2 Abut 3 Equation 6.7: a = Y �V�n�2 Yo-i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.0 1.8 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K, 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Yo 3.1 3.5 ft Upstream flow depth T 1 1.3 1.3 N/m^2=Pa lCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83V2 p Ys—utr = 0.94y1 — / 9Yl gnyl a Variable Value Unit Description Y, 1.0 1.1 m Upstream average flow depth VZ 0.6 0.5 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for 5.1. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity Ys .ic 1 0.2 0.2 1 m Ultimate contraction scour Ys we 1 0.8 0.7 Ift I Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 2 Page 751 of 1059 US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB Off Ramp Support Abut 1 Bent 2 Equation 6.7: a = YV2n�2 Yo-1/3 I( KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4lb/ftA3 and 9800 N/mA3) VZ 3.0 2.6 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.0 2.8 ft Upstream flow depth is 1.3 1.3 N/mA2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc (�3VZ " p Ys—.It = 0.94y1 — / 9Y1 1 3 gny Variable Value Unit Description y1 0.6 0.9 m Upstream average flow depth Vz 0.9 0.8 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/mA3 Density of water g 9.81 9.81 m/sA2 acceleration due to gravity y, uic 1 0.3 0.3 m Ultimate contraction scour Ys we 1 1.1 1 1.1 ift JUltimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 3 Page 752 of 1059 1=37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB On Ramp Support Bent 2 Abut 3 Equation 6.7: a = Y �V�n�2 Yo-i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 0.4 2.0 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K, 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Yo 2.2 4.2 ft Upstream flow depth T 1 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83V2 p Ys—utr = 0.94y1 — / 9Yl gnyl a Variable Value Unit Description Y, 0.7 1.3 m Upstream average flow depth VZ 0.1 0.6 m/s Average velocity in contracted section K, 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity Ys .ic 1 0.0 0.3 m Ultimate contraction scour Ys we 1 0.0 1 0.9 ift Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 4 Page 753 of 1059 US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge MSE Walls Support Intersection of Prado Rd with US 101 Ramps Equation 6.7: T = Y V2n2 YD-1/3 (K,) Variable Value Unit Description g 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.4 ft/s average velocity in contracted section n 0.04 Manning's roughness coefficient K, 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 4.8 ft Upstream flow depth T 1 1.3 NTm 2=Pa Critical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (�3VZ " p Ys—.It = 0.94y1 — / 9Y1 1 3 gny Variable Value Unit Description y1 1.5 m Upstream average flow depth Vz 0.7 m/s Average velocity in contracted section K, 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 kg/m^3 Density of water g 9.81 m/s^2 acceleration due to gravity ys .ic 1 0.4 m Ultimate contraction scour y� ui, 11.2 Ift I Ultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 5 Page 754 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: vl� ) Ys = 2.2K1KZa0.65 2.6V1 — VC 0.7 Variable Value Unit Description Bridge Prado Road West Overcrossing Support Bent 2 Bent 3 # of Columns 3 3 a 5 5 ft Pier width L 15 15 ft Pier length L/a 3 3 If L/a is larger than 12, then use 12 as a maximum 6 0 30 degrees Angle of attack of flow Group of cylinders Group of cylinders Pier shape K1 1 1 Correction factor for pier shape K2 1.0 1.8 Correction factor for angle of attack V1 2.6 2.8 ft/s Approach velocity Vc 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 ft/sA2 ys 5.9 1 11.0 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 6 Page 755 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 100-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K11CZa0.65 2.6y1—V, 0.7 Variable Value Unit Description Bridge Prado Road East Overcrossin US 101 NB Off Ramp US 101 NB On Ramp Support Bent 2 Bent 2 Bent 2 # of Columns 4 2 2 a 5 4 4 ft Pier width L 20 8 8 ft Pier length L/a 4 2 2 If L/a is larger than 12, then use 12 as a maximum e 0 0 0 degrees Angle of attack of flow Group of cylinders Group of cylinders Group of cylinders Pier shape K1 1 1 1 Correction factor for pier shape K2 1.0 1.0 1.0 Correction factor for angle of attack V1 2.1 2.9 1.2 ft/s Approach velocity Vc 0.5 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 1 5.6 32.2 ft/sA2 1 2.0 ft ys 4.7 Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 7 Page 756 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition Prado Road West Overcrossing Units = (Metric or English) English Right Overbank = Abutment 1 (West) y1= Upstream flow depth 2.2 ft Upstream velocity 2.5 ft/s Upstream flow 2802.0 cfs Upstream channel width 552.4 ft q1 = Upstream unit discharge 5.5 ft2/s Flow depth through bridge 2.6 ft Velocity through bridge 4.3 ft/s Flow through bridge 2968.7 cfs Bridge opening width less pier widths 409.5 ft q2 = Unit discharge in the constricted opening 11.4 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = (� )3/7 quf /f Equation 8.7 t, = Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 15.5 Ift Ymax = aAYc or Ymax = aBYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.5 2.1 Wingwall 1.93 10.5 2.6 7.9 1.7 6.2 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 8 Page 757 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition Prado Road East Overcrossing Units = (Metric or English) English Left Overbank = Abutment 3 (East) y1= Upstream flow depth 3.5 ft Upstream velocity 2.2 ft/s Upstream flow 2416.9 cfs Upstream channel width 210.1 ft q1 = Upstream unit discharge 7.6 ft2/s Flow depth through bridge 3.3 ft Velocity through bridge 1.8 ft/s Flow through bridge 1530.2 cfs Bridge opening width less pier widths 261.1 ft q2 = Unit discharge in the constricted opening 5.8 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 15.6 Ift Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.6 0.8 Wingwall 1.00 5.6 3.3 2.3 0.7 1.6 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 9 Page 758 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition US 101 NB Off Ramp Units = (Metric or English) English Left Overbank = Abutment 1 (South) y1= Upstream flow depth 2.0 ft Upstream velocity 2.3 ft/s Upstream flow 1514.1 cfs Upstream channel width 337.3 ft q1 = Upstream unit discharge 4.5 ft2/s Flow depth through bridge 2.0 ft Velocity through bridge 3.0 ft/s Flow through bridge 1319.9 cfs Bridge opening width less pier widths 232.4 ft q2 = Unit discharge in the constricted opening 6.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.112 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 13.2 Ift Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 3.2 1.4 Wingwall 2.47 8.0 2.0 5.9 1.1 4.8 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 10 Page 759 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition US 101 NB On Ramp Units = (Metric or English) English Right Overbank = Abutment 3 (North) y1 = Upstream flow depth 4.2 ft Upstream velocity 1.6 ft/s Upstream flow 2602.6 cfs Upstream channel width 154.3 ft q1 = Upstream unit discharge 6.5 ft2/s Flow depth through bridge 4.0 ft Velocity through bridge 2.0 ft/s Flow through bridge 2119.5 cfs Bridge opening width less pier widths 93.3 ft q2 = Unit discharge in the constricted opening 8.1 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = C� 13/7 C quf / f Equation 8.7 i, = Critical shear stress for the floodplain material 0.112 lb/ft-2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 lb/ft-3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 4.1 ft Ymax = aAYc OrYmax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q 2/q 1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 4.1 1.3 Wingwall 2.57 10.5 4.0 6.5 0.9 5.6 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 11 Page 760 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Left Overbank = MSE Walls at the South y1= Upstream flow depth 4.1 ft Upstream velocity 2.3 ft/s Upstream flow 1128.2 cfs Upstream channel width 146.5 ft q1 = Upstream unit discharge 9.5 ft2/s Flow depth through bridge 4.2 ft Velocity through bridge 1.7 ft/s Flow through bridge 1361.0 cfs Bridge opening width less pier widths 172.1 ft q2 = Unit discharge in the constricted opening 7.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = (� )3/7 quf /f Equation 8.7 t, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 16.8 Ift Ymax = aAYc or Ymax = aBYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 6.8 0.8 Wingwall 1.00 6.8 4.2 2.6 1.2 1.4 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 12 Page 761 of 1059 F37Z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 100-year Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Right Overbank = MSE Walls at the North y1= Upstream flow depth 4.7 ft Upstream velocity 2.1 ft/s Upstream flow 1127.4 cfs Upstream channel width 262.5 ft q1 = Upstream unit discharge 9.9 ft2/s Flow depth through bridge 3.0 ft Velocity through bridge 2.1 ft/s Flow through bridge 955.2 cfs Bridge opening width less pier widths 290.5 ft q2 = Unit discharge in the constricted opening 6.2 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = (� )3/7 quf / f Equation 8.7 t, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 5.9 ft Ymax = aAYc or Ymax = aBYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.9 0.6 Wingwall 1.00 5.9 3.0 3.0 1.2 1.7 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 13 Page 762 of 1059 US 101 at Prado Road Interchange Project (Project No. 2091613-02 1 Caltrans EA 05-11-1640) 200-year Scour Summary Tables Scour Data Tables Prado West Overcrossing, Bridge No. 49C#### Prado West Overcrossing, Bridge No. 49C#### Short Term (Local)a MMMM Long Term (Degradation andShort Term ft) Scour Depth (ft) Contraction) lft) ur Elevation Scour Der Bent 3 1 Bent 3 130.41 • Prado East Overcrossing, Bridge No. 49C#### Prado East Overcrossing, Bridge No. 49C#### Support Degradation M No. Scour Depth (ft) Scour Depth (ft) Short Term Contraction) (Sftj ur Elevation Scour Der a • 1Abut 3 132.0 2.9 US 101 NB • • Bridge No.49 #### US 101• • Bridge No. Short Term (Local)Short EMMM Term ft) Scour Depth (ft) No. Contraction) (Sftj ur Elevation Scour Der .• US 101 NB • • Bridge No. 49 #### US 101: • • Bridge No. 49 Support Degradation Contraction Short Term (Local) No. Scour Depth (ft) Scour Depth (ft) Scour Depth (ft) Support Long Term (Degradation and Short Term No. Contraction) (Sftj ur Elevation Scour Der Bent 2 N/A 11 2.7 Bent 2 133.0 2.7 Page 763 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge Prado Road West Overcrossing Support Abut 1 Bent 2 Bent 3 Equation /6.7: \ i=YI- IZyo-i/a KU Variable Value Unit Description g 62.4 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 4.9 4.1 4.0 ft/s average velocity in contracted section n 0.04 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 2.5 2.5 1.7 ft Upstream flow depth i 1.3 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS-ua = 0.94y1 - / a 9Yi gny1 Variable Value Unit Description yl 0.7 0.8 0.5 m Upstream average flow depth Vz 1.5 1.3 1.2 m/s Average velocity in contracted section K 1 1 1 1.486 for U.S. Customary, and 1.0 for S.I. P 1000 1000 1000 kg/m^3 Density of water g 9.81 9.81 9.81 m/s^2 acceleration due to gravity ys .k 1 0.6 0.5 0.4 m Jultimate contraction scour y= i, 1 2.1 1 1.7 1 1.4 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 1 Page 764 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge Prado Road East Overcrossing Support Bent 2 Abut 3 Equation /6.7: \ i=YI— IZyo—i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.5 2.2 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 3.5 3.8 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS—ua = 0.94y1 — / a 9Yi gny1 Variable Value Unit Description yl 1.1 1.2 m Upstream average flow depth Vz 0.8 0.7 m/s Average velocity in contracted section K 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity ys .k 1 0.3 0.3 im jultimate contraction scour y= i, 1 1.1 1 1.0 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 2 Page 765 of 1059 FDR US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-185th Edition Project Bridges Bridge US 101 NB Off Ramp Support Abut 1 Bent 2 Equation /6.7: \ i=YI— IZyo—i/a KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 3.4 2.9 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient <„ 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. Y. 2.2 3.3 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure 6.11) Equation 6.6: K Tc (13vZ p YS—ua = 0.94y1 — / a 9Yi gny1 Variable Value Unit Description yl 0.7 1.0 m Upstream average flow depth Vz 1.0 0.9 m/s Average velocity in contracted section K 1 1 1.486 for U.S. Customary, and 1.0 for S.I. p 1000 1000 kg/m^3 Density of water g 9.81 9.81 m/s^2 acceleration due to gravity ys ue 0.4 0.4 m Ultimate contraction scour y= i, 1 1.3 1 1.3 ft Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 3 Page 766 of 1059 FN US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge US 101 NB On Ramp Support Bent 2 Abut 3 Equation 6.7: T = Y �_)2 A-1/3 KU Variable Value Unit Description g 62.4 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 0.5 2.5 ft/s average velocity in contracted section n 0.04 0.04 Manning's roughness coefficient K 1.486 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 2.7 4.7 ft Upstream flow depth i 1.3 1.3 N/m^2=Pa JCritical shear stress of channel bed material (From Figure Equation 6.6: K Tc 1.83VZ p gY1 gnyl 3 Variable Value Unit Description yl 0.8 1.4 m Upstream average flow depth Average velocity in contracted section 1.486 for U.S. Customary, and 1.0 for S.I. Density of water acceleration due to gravity Vz 0.1 0.8 m/s K 1 1 p 1000 1000 kg/m^3 g 9.81 9.81 m/s^2 y= .k 1 0.0 0.4 m jultimate contraction scour y= i, 1 0.0 1 1.3 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg 4 Page 767 of 1059 FN US 101 at Prado Road Interchange Project City of San Luis Obispo Ultimate (Contraction) Scour 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Bridge VISE Walls Support Intersection of Prado Rd with US 101 Ramps Equation 6.7: T = Y �_)2 A-1/3 KU Variable Value Unit Description g 62.4 Ib/ft^3 unit weight of water (62.4 Ib/ft^3 and 9800 N/m^3) Vz 2.4 ft/s average velocity in contracted section n 0.04 Manning's roughness coefficient K 1.486 1.486 for U.S. Customary, and 1.0 for S.I. yo 4.8 ft Upstream flow depth i 1.3 N/m^2=Pa Critical shear stress of channel bed material (From Figure 6.11) Equation 6.6: (K Tc �;3VZ pY1 gnyl 3 Variable Value Unit Description yl 1.5 m Upstream average flow depth Vz 0.7 m/s Average velocity in contracted section K 1 1.486 for U.S. Customary, and 1.0 for S.I. P 1000 kg/m^3 Density of water g 9.81 m/s^2 acceleration due to gravity y= .k 0.4 Im jultimate contraction scour y= i, 11.2 Ift Jultimate contraction scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 Pg 5 Page 768 of 1059 F:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K,.K a0.6s (2.6V, — V, o.7 Variable Value Unit Description Bridge Prado Road West Overcrossing Support Bent 2 Bent 3 # of Columns 3 3 a 5 5 ft Pier width L 15 15 ft Pier length L/a 3 3 If L/a is larger than 12, then use 12 as a maximum 6 0 30 degrees Angle of attack of flow Group of Group of cylinders cylinders Piershape K1 1 1 Correction factor for pier shape K2 1.0 1.8 Correction factor for angle of attack V1 3.0 3.4 ft/s Approach velocity Vc 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 ft/s^2 ys 6.7 13.0 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 6 Page 769 of 1059 F:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Piers - Cohesive 200-year Calculation guideline from HEC-18 5th Edition Project Bridges Equation 7.35: YS = 2.2K1KZa0.65 (2.6V, — V, o.7 Variable Value Unit Description Bridge Prado Road East US 101 NB Off US 101 NB On Overcrossing Ramp Ramp Support Bent 2 Bent 2 Bent 2 # of Columns 2 4 2 a 5 4 4 ft Pier width L 20 8 8 ft Pier length L/a 4 2 2 If L/a is larger than 12, then use 12 as a maximum 6 0 0 0 degrees Angle of attack of flow Group of Group of Group of cylinders cylinders cylinders Piershape K1 1 1 1 Correction factor for pier shape K2 1.0 1.0 1.0 Correction factor for angle of attack V1 2.6 3.4 1.5 ft/s Approach velocity Vc 0.5 0.5 0.5 m/s critical velocity (from Figure 4.7 in HEC-18) Vc 1.7 1.7 1.7 ft/s critical velocity (from Figure 4.7 in HEC-18) g 32.2 32.2 32.2 ft/s^2 ys 5.9 6.4 2.7 ft Pier Scour hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 7 Page 770 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition Prado Road West Overcrossing Units = (Metric or English) I English Right Overbank = Abutment 1 (West) y1 = Upstream flow depth 2.5 ft Upstream velocity 2.8 ft/s Upstream flow 3628.7 cfs Upstream channel width 559.6 ft q1 = Upstream unit discharge 6.9 ft2/s Flow depth through bridge 3.0 ft Velocity through bridge 4.9 ft/s Flow through bridge 3890.8 cfs Bridge opening width less pier widths 420.4 ft q2 = Unit discharge in the constricted opening 14.7 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour 3/7 6 Yc = Ci ( ) Equation 8.7 / Kuf Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 6.8 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 6.8 2.1 Wingwall 1.89 12.9 3.0 9.9 2.1 7.8 ft Ft Ft Ft Ft Ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 8 Page 771 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition Prado Road East Overcrossing Units = (Metric or English) English Left Overbank = Abutment 3 (East) y1 = Upstream flow depth 3.8 ft Upstream velocity 2.7 ft/s Upstream flow 3353.3 cfs Upstream channel width 220.4 ft q1 = Upstream unit discharge 10.3 ft2/s Flow depth through bridge 3.8 ft Velocity through bridge 2.2 ft/s Flow through bridge 2300.0 cfs Bridge opening width less pier widths 284.6 ft q2 = Unit discharge in the constricted opening 8.3 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = Ci / 3/7 ( Kuf ) 6 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 7.6 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.6 0.8 Wingwall 1.00 7.6 3.8 3.8 1.0 2.9 rt rt rt rt rt hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 9 Page 772 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition US 101 NB Off Ramp Units = (Metric or English) English Left Overbank = Abutment 1 (South) y1 = Upstream flow depth 2.2 ft Upstream velocity 2.5 ft/s Upstream flow 1845.0 cfs Upstream channel width 337.3 ft q1 = Upstream unit discharge 5.4 ft2/s Flow depth through bridge 2.2 ft Velocity through bridge 3.4 ft/s Flow through bridge 1587.8 cfs Bridge opening width less pier widths 237.3 ft q2 = Unit discharge in the constricted opening 7.3 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour Yc = Ci / 3/7 ( Kuf ) 6 Equation 8.7 2c = Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 3.7 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 3.7 1.4 Wingwall 2.49 9.3 2.2 7.1 1.3 5.8 ft ft Ft Ft Ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 10 Page 773 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition US 101 NB On Ramp Units = (Metric or English) English Right Overbank = Abutment 3 (North) y1 = Upstream flow depth 4.7 ft Upstream velocity 1.8 ft/s Upstream flow 3621.2 cfs Upstream channel width 144.7 ft q1 = Upstream unit discharge 8.3 ft2/s Flow depth through bridge 4.7 ft Velocity through bridge 2.5 ft/s Flow through bridge 2886.0 cfs Bridge opening width less pier widths 103.3 ft q2 = Unit discharge in the constricted opening 11.9 ft2/s Abutment scour equation = I Alternative Clear -Water Alternative Clear-Wat1er Condition Abutment Scour Yc = I i 13/7 I K. 16 Equation 8.7 2c = Critical shear stress for the floodplain material 0.112 Ib/ftA2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ftA3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 1 5.7 Ift Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 5.7 1.4 Wingwall 2.42 13.7 4.7 9.0 1.3 7.7 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 11 Page 774 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Left Overbank = MSE Walls at the South y1 = Upstream flow depth 4.5 ft Upstream velocity 2.9 ft/s Upstream flow 1615.4 cfs Upstream channel width 146.5 ft q1 = Upstream unit discharge 12.9 ft2/s Flow depth through bridge 4.4 ft Velocity through bridge 1.9 ft/s Flow through bridge 1875.2 cfs Bridge opening width less pier widths 192.4 ft q2 = Unit discharge in the constricted opening 8.4 ft2/s Abutment scour equation = Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour .yc = I � 13/7 I �uf 16 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ft^2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ft^3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 7.7 ft Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.7 0.7 Wingwall 1.00 7.7 4.4 3.3 1.2 2.1 ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 12 Page 775 of 1059 1=:)7z US 101 at Prado Road Interchange Project City of San Luis Obispo Local Scour at Abutments - NCHRP 200-yea r Calculation guideline from HEC-18 5th Edition MSE Walls Units = (Metric or English) English Right Overbank = MSE Walls at the North y1 = Upstream flow depth 5.0 ft Upstream velocity 2.6 ft/s Upstream flow 1519.9 cfs Upstream channel width 266.2 ft q1 = Upstream unit discharge 13.0 ft2/s Flow depth through bridge 3.2 ft Velocity through bridge 2.4 ft/s Flow through bridge 1308.2 cfs Bridge opening width less pier widths 297.3 ft q2 = Unit discharge in the constricted opening 7.7 ft2/s Abutment scour equation = Alternative Clear -Water Alternative Clear -Water Condition Abutment Scour .yc = I � 13/7 I �uf 16 Equation 8.7 i, = Critical shear stress for the floodplain material 0.027 Ib/ft^2 n = Manning n of the floodplain material under the bridge 0.040 y = Unit weight of water 62.4 Ib/ft^3 Ku = 1.486 English units, 1.0 SI units 1.486 yc = Flow depth including contraction scour 7.2 ft Ymax = aAYc or Ymax = asYc Equation 8.3 Ys = Ymax — Yo Equation 8.4 yc = Flow depth including live -bed or clear -water contraction scour q2/q1 Type of abutment (Wingwall vs Spill -through) aB = Amplification factor for clear -water conditions y max = Maximum flow depth resulting from abutment scour y0 = Flow depth prior to scour ys = Abutment scour depth Contraction scour component Local scour component Note: ys is a combination of local and contraction scour. 7.2 0.6 Wingwall 1.00 7.2 3.2 4.0 1.2 2.8 ft ft ft ft ft ft hdrinc.com 3003 Oak Road, Suite 500, Walnut Creek, CA 94597 925.465.2700 pg. 13 Page 776 of 1059 DRAFT n, consor APPENDIX G: Draft SPGR Page 777 of 1059 STRUCTURE PRELIMINARY GEOTECHNICAL REPORT Earth Retaining Structures US 101 at Prado Road Interchange Project San Luis Obispo, California 05-SLO-101- PM 26.5-27.3 Caltrans Project No. 113-0000-0405; EA 05-111640 City Specification No. 2091613-02 Yeh Project No.: 223-400 December 23, 2025 INDEPENDENT QUALITY CONTROL REVIEW US 101 and Prado Road Interchange Project INITIAL' c--E DESIGNER%ORIGINATr_R 12/18/25 PE -RC CONFIRMS READY FOR QC 12/18/25 INDEPENDENT QC REVIEW DONE 12/22/25 r, .h ,•s , I PE- RC CONCURS WITH QC REVIEW 12/23/25 QC COMMENTS INCORPORATED 12/23/25 QC COMMENTS BACKCHECKED/VERIFIED 12/23/25 Prepared for: Consor North America, Inc. 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95670 Attn: Dace Morgan, P.E. Prepared by: Yeh and Associates, Inc. 391 Front Street, Suite D Grover Beach, California 93433 Phone: 805-481-9590 INYeh and Associates, Inc. Geotechnical • Geological • Construction Services Page 778 of 1059 VYeh and Associates, Inc. Geotechnical • Geological • Construction Services December 23, 2025 Consor North America, Inc. 2868 Prospect Park Drive, Suite 250 Rancho Cordova, CA 95670 391 Front Street, Suite D Grover Beach, CA 93433 (805) 481-9590 www.yeh-eng.com Project No. 223-400 Attn: Dace Morgan, P.E. Subject: vnr Structure Preliminary Geotechnical Report — Earth Retaining Structures (ERS), US 101 at Prado Road Interchange Project, San Luis Obispo, California, 05-SLO-101- PM26.5-27.3, Caltrans Project No. 113-0000-0405; EA 05-11-11640, City Specification No. 2091613-02 Dear Ms. Morgan: Yeh and Associates, Inc. is pleased to submit this Structure Preliminary Geotechnical Report for the design of earth retaining structures (ERS) for improvements associated with the U.S. Route 101 (US 101) and Prado Road Interchange Project in San Luis Obispo, California. Our geotechnical services are being provided in accordance with the terms of agreement between Yeh and Associates and Consor North America, Inc. (Consor) dated April 11, 2025. This report provides preliminary geotechnical recommendations for ERS for the two currently proposed alternatives (Alternatives 1 and 2) as input for type selection for Phase 1 of the Plans, Specification and Estimate (PS&E). Both alternatives will result in similar geotechnical considerations. This report was prepared in general accordance with Caltrans' February 2021 Geotechnical Design Reports guidelines. Yeh is also preparing a separate Preliminary Geotechnical Design Report (PGDR) for roadway improvements and a Structure Preliminary Geotechnical Report (SPGR) for the US 101 overcrossing and viaducts that will support the new northbound ramps. We appreciate the opportunity to be of service. Please contact Judd King at 805-481-9590 x285 or jkin@yeh-en.com if you have questions or require additional information. Sincerely, YEH AND ASSOCIATES, INC. DRAFT Judd J. King, PE, GE Senior Geotechnical Engineer Colorado DRAFT Jamie L. Ross, PE, GE Senior Project Engineer California Denver I Colorado Springs I Durango I Glenwood Springs I Grand Junction I Greeley Grover Beach I Ventura Page 779 of 1059 Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project DRAFT Katrina Ocampo, EIT Engineering Intern Colorado Reviewed by: DRAFT Gregg L. Fiegel, PhD, PE, GE Senior Project Specialist Project No. 223-070 December 23, 2025 California Denver I Colorado Springs I Durango I Glenwood Springs I Grand Junction I Greeley Grover Beach I Ventura Page 780 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Table of Contents Project No. 223-400 December 23, 2025 1. INTRODUCTION.........................................................................................................................1 2. PROJECT DESCRIPTION..............................................................................................................1 2.1 GENERAL IMPROVEMENTS..............................................................................................................1 2.2 PROPOSED ERS LOCATIONS............................................................................................................2 3. GEOTECHNICAL EXPLORATION..................................................................................................3 3.1 CONE PENETRATION TEST (CPT) SOUNDINGS....................................................................................3 3.2 PREVIOUS STUDIES.......................................................................................................................4 4. GEOTECHNICAL CONDITIONS.....................................................................................................5 4.1 GEOLOGY...................................................................................................................................5 4.2 SURFACE CONDITIONS...................................................................................................................7 4.2.1 TERRAIN AND TOPOGRAPHY.................................................................................................... 7 4.2.2 SURFACE WATER AND DRAINAGE............................................................................................. 7 4.2.3 EXISTING FACILITY................................................................................................................7 4.2.4 EXISTING UTILITIES...............................................................................................................7 4.3 SUBSURFACE CONDITIONS..............................................................................................................8 5. GROUNDWATER........................................................................................................................9 6. SCOUR DATA...........................................................................................................................11 7. CORROSION EVALUATION.......................................................................................................12 8. SEISMIC INFORMATION...........................................................................................................12 8.1 GROUND MOTION HAZARD..........................................................................................................12 8.1.1 GROUND MOTION PARAMETERS...........................................................................................12 8.1.2 SEISMIC SLOPE STABILITY PARAMETERS...................................................................................15 8.2 OTHER SEISMIC HAZARDS............................................................................................................15 8.2.1 SURFACE FAULT RUPTURE....................................................................................................15 8.2.2 LIQUEFACTION...................................................................................................................15 8.2.3 SEISMICALLY INDUCED GROUND SETTLEMENTS.........................................................................16 8.2.4 LIQUEFACTION -INDUCED LATERAL SPREADING..........................................................................16 8.2.5 SEISMIC SLOPE INSTABILITY................................................................................................... 16 9. PRELIMINARY GEOTECHNICAL RECOMMENDATIONS..............................................................16 9.1 PRELIMINARY GEOTECHNICAL RECOMMENDATIONS FOR EARTH RETAINING STRUCTURES (ERS) ..................16 VA iv Page 781 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 9.1.1 CONVENTIONAL RETAINING WALLS........................................................................................19 9.1.2 MECHANICALLY STABILIZED EMBANKMENT (MSE) WALLS..........................................................20 9.1.3 MODIFIED CONVENTIONAL RETAINING WALLS SUPPORTED ON DEEP FOUNDATIONS .........................22 9.1.4 RECOMMENDED EARTH RETAINING STRUCTURE (ERS) TYPES......................................................24 10. ADDITIONAL FIELD WORK AND LABORATORY TESTING.......................................................24 11. LIMITATIONS.......................................................................................................................25 12. REFERENCES........................................................................................................................25 List of Plates Previous and Current Field Exploration Map..........................................................................................................1 SubsurfaceProfile A-A............................................................................................................................................. 2 SubsurfaceProfile B-B.............................................................................................................................................3 List of Figures FIGURE1: VICINITY MAP.............................................................................................................................................. 1 FIGURE 2: PROPOSED LAYOUT (CONSOR 2025B)............................................................................................................. 2 FIGURE 3: GEOLOGIC MAP (WIEGERS 2010)................................................................................................................... 6 FIGURE 4: PRELIMINARY ARS CURVE............................................................................................................................ 13 List of Tables TABLE 1: DESCRIPTION OF THE PROPOSED ERS................................................................................................................. 3 TABLE 2: SUMMARY OF GROUNDWATER MEASUREMENTS................................................................................................. 9 TABLE 3: RECOMMENDED GROUND MOTION PARAMETERS FOR PRELIMINARY GEOTECHNICAL DESIGN ................................... 13 TABLE 4: RECOMMENDED HORIZONTAL PSEUDOSTATIC COEFFICIENT FOR PRELIMINARY DESIGN ............................................ 15 List of Appendices Page Appendix A — CPT Soundings and Liquefaction Analyses 25CPT-01 to 04.................................................................................................................... A-1 to 32 Appendix B — Relevant Historical Data — Borings, CPTs, Geophysical Surveys and Laboratory Madonna Road OC (Caltrans 1961)...............................................................................................B-1 Laguna Lift Station (Fugro 1999)......................................................................................... B-2 to 17 San Luis Obispo Water Reuse (Fugro 2002)...................................................................... B-18 to 34 Prado Road OC at US 101 (Parikh 2002).....................................................................................B-35 SLO PCE Plume Characterization (WSC 2022)................................................................... B-36 to 49 Prado Road Bridge (Yeh 2025)........................................................................................ B-50 to 100 ,A v Page 782 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 1. INTRODUCTION Consor retained Yeh and Associates to provide preliminary geotechnical �- R CITY OF recommendations for the design of SAN LUIS OBISPO PM the US 101 and Prado Road 273 Interchange Project in San Luis PROJECT LOCATION i Obispo, California. The project ode includes reconstruction of the northbound ramps, an auxillary lane connecting to the Madonna Road PM \ interchange to the north, realignment 26. Prado Road of Elks Lane, and the new Prado Road overcrossing at US 101. Project limits extend about a %-mile south from the J North existing Madonna Road Interchange ' and through the existing at -grade m intersection with the northbound F I ramps of the existing Prado 40 0 3,000 Interchange. j feet Base Map: AtcGIS Earth (2017) The project location is shown in Figure 1: Vicinity Map Figure 1. This report provides preliminary geotechnical considerations and recommendations for the proposed ERS relative to foundation support, scour, corrosion, seismic hazards, ERS type, construction, and additional field work and laboratory testing for design. The preliminary characterization of the subsurface conditions is based on boring information from previous explorations performed in the vicinity of the project site and cone penetration tests performed for this study (see Section 3.1). A Structure Preliminary Geotechnical Report (SPGR) for Bridges will be submitted separately for the proposed overcrossing and approach ramps connecting Prado Road to Dalidio Drive. 2. PROJECT DESCRIPTION 2.1 GENERAL IMPROVEMENTS Preliminary alignment and design information for the project was provided by Consor (2025a, 2025b). The project generally consists of the extension of Prado Road over US 101 to connect to Dalidio Drive within the City of San Luis Obispo and reconstruction of the interchange. The project limits will extend along US 101 from approximately Post Mile (PM) 26.5 at the southern limits of the project site I � 1 Page 783 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 to PM 27.3 at the Madonna Road northbound off -ramp. The approach from Prado Road will extend for about 1,000 feet from the existing Prado Road Bridge at San Luis Obispo Creek to an existing roundabout at the eastern terminus of Dalidio Drive about 500 feet west of US 101. The approved project is described as Alternative 3 in the Project Report (GHD 2018) and environmental documents (Caltrans 2023). The City and Consor have been conducting a Value Analysis to determine if improvements to the approved project could be made to reduce the overall construction cost of the improvements. On November 4, 2025, the City Council approved modifying the approved project from the Project Report to the one shown in Figure 2. convor Figure 2: Proposed Layout (Consor 2025b) The new interchange will essentially be a half -diamond, consisting of northbound ramps and at -grade controlled intersections. The project components include the west side and east side approaches to the overcrossing, the elevated northbound US 101 on- and off -ramps, and the northbound US 101 auxiliary lane between Prado Road and Madonna Road. Both the west side and east side approaches for the overcrossing need to be elevated to connect to the proposed bridge over US 101. Earth retaining structures (ERS) are proposed to support the approaches to the overcrossing and the elevated northbound ramps. The project is also within a mapped flood zone. As a result, the structures will be elevated above grade to limit impacts to the mapped flood zone (GHD 2018). 2.2 PROPOSED ERS LOCATIONS Table 1 presents information for the proposed earth retaining structures (ERS) for the project. Note that stationing, dimensions, and other descriptions in Table 1 are approximate and based on conceptual plans (Consor 2025a, 2025b). IA 2 Page 784 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Table 1: Description of the Proposed ERS Project No. 223-400 December 23, 2025 ERS Begin Station & End Station & Design Length Maximum Design Height Line Type Offset Offset Prado mainline west 44+66 46+27 side, twin structures P * Left/ 44+84 Left/Right 143 to 161 20 on left and right Right sides of approach Prado mainline east 56+72 57+77 side, twin structures P * Left/Right Left/57+41 69 to 105 5 on left and right Right sides of approach Northbound US 101 off -ramp, twin NB Off * 207 20 structures on left Left/Right Left/Right and right sides of off - ramp Northbound US 101 32+95 36+23 on -ramp, twin NB On * Left/Right Left/37+96 328 to 501 20 structures on left Right and right sides of on - ramp * = Information not yet available 3. GEOTECHNICAL EXPLORATION This geotechnical evaluation was based on review of geotechnical data collected from various previous studies and the results of four Cone Penetration Test (CPT) soundings performed for this phase of the project. The locations of the CPTs performed for this study are shown on Plate 1 along with explorations completed for previous studies. The logs for the CPT soundings are presented in Appendix A and previous study data is presented in Appendix B. 3.1 CONE PENETRATION TEST (CPT) SOUNDINGS The CPT subcontractor for this project was Gregg Drilling (Gregg) of Signal Hill, California. Gregg advanced four soundings using a hydraulic ram mounted inside a 30-ton truck on July 10, 11, and 29, 2025. CPT soundings were advanced to depths ranging from approximately 57 to 62 feet below the ground surface. Each sounding was terminated once refusal was encountered. Refusal was characterized by lifting or tilting of the CPT rig due to high push load. Once a sounding was completed, the void above the refusal depth was backfilled with bentonite chips. Plate 1 shows the approximate locations of the four CPT soundings (25CPT-01 through 25CPT-04) relative to the proposed interchange improvements. Logs of the CPT soundings are presented in Appendix A. YA 3 Page 785 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 The soundings were performed in general accordance with ASTM D-5778 using an electric piezocone penetrometer. The piezocone penetrometer had a diameter of approximately 1.7 inches with a tip area of 15 square centimeters (cmZ) and a sleeve area of 225 cmz. The cone tip resistance (qJ, sleeve friction (fs), and penetration pore water pressures measured behind the tip (in the uz location) were recorded at approximately 3-centimeter intervals during penetration using an on -board computer. The friction ratio (FR, the ratio of sleeve friction to tip resistance in percent) was computed for each value of q, and fs recorded. The data and soil behavior type classifications were used in subsequent geotechnical analyses and to evaluate soil types and boundaries for analyses. Seismic shear wave velocity testing was performed in CPT soundings 25CPT-01 through 25CPT-04. To conduct the seismic shear wave test, the penetration of the cone was stopped, and the rods were decoupled from the rig. An automatic hammer was then triggered to send a shear wave into the ground. The distance from the source to the cone was calculated knowing the total depth of the cone and the horizontal offset distance between the hammer and the cone. A minimum of two tests must be performed at two different depths to calculate an interval shear wave velocity. The data collected was used to estimate an average shear wave velocity extrapolated to a depth of 100 feet below the project site (Vs30). 3.2 PREVIOUS STUDIES Previous geotechnical studies that were performed at or near the project location were reviewed for this project. Logs and laboratory data pertinent to this project included in Appendix B. The locations of the previous borings and CPT soundings are shown on Plate 1. Pertinent studies and data that were reviewed include: • Nine borings (B-1 through B-9) drilled by Caltrans (1961b) for the design of the overcrossing structure at US 101 and Los Osos Valley Road; • Four borings (B-1 through B-4) drilled by Caltrans (Caltrans 1963) for the design of the overcrossing structure at US 101 and Madonna Road; • Pile driving records from Caltrans (1961a, 1962, 1986), and MNS (2015) for the overcrossing structure at US 101 and Los Osos Valley Road as well as pile driving records from 1961 and 1962 for the overcrossing structure at US 101 and Madonna Road; • A study performed by Unocal (GeoResearch-Unocal 1990) for the evaluation of contaminated soil on Elks Lane at San Luis Obispo Creek. The evaluation included three borings (B-1 through B-3) and a monitoring well installed at the site. A well destruction report for the well was also prepared by Arcadis (2019); • Three borings (DH 1 through 3) drilled by Fugro (1999) for a proposed lift station at the SLO Water Reclamation Facility (WRF); 11"rA 4 Page 786 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 • Five borings (B-305, 306, 401 through 403) drilled by Fugro (2002) for a proposed pipeline and reservoir for a recycled water project at the WRF; • Two borings (B-1 and B-2) drilled by Parikh (2002) for a proposed overcrossing structure at US 101 and Prado Road; • A study performed by Caltrans (2005) for the evaluation of an auxiliary lane on northbound US 101 between Prado Road and Madonna Road; • A study performed by Dokken Engineering (2009) for the widening of the overcrossing structure at US 101 and Los Osos Valley Road. The evaluation included twenty-seven borings (B-1 through B-27) drilled at the overcrossing; • A study performed by WSC (2022) for characterization and remediation of a PCE plume. The study included exploratory borings and cone penetration test (CPT) soundings, including two borings (B-21 and B-24) as well as four CPT soundings (B-18R and B-22 through B-24) within the project limits; and • A geotechnical study performed by Yeh (2025) for the Prado Road Bridge Replacement Project immediately east of the project limits. The study includes data from exploratory borings and a geophysical survey. Exploratory borings by Earth Systems drilled in 2008 and 2015 are also included in this study. 4. GEOTECHNICAL CONDITIONS 4.1 GEOLOGY The project site lies east of the Santa Lucia Range and within the Coast Ranges Geomorphic Province, which extends from the Transverse Ranges in southern California to the Klamath Mountains in northern California and into Oregon. The province is characterized by north to northwest trending mountain ranges bounded by the Pacific Ocean to the west and the Central Valley of California to the east. The ranges are predominantly composed of Jurassic- and Cretaceous -age rocks with Tertiary -age rock and Holocene sediments commonly overlying the older formations along the flanks and foothills of those ranges. Quaternary sediments are found within intervening drainages, valleys, and coastal areas. The regional geology as mapped by Wiegers (2010) is shown in Figure 3. Wiegers maps the surface geology in the site vicinity as units of Holocene to late Pleistocene age young alluvial floodplain deposits (Qya2). The young alluvial floodplain deposits are described by Wiegers as "unconsolidated sand, silt, and clay -bearing alluvium deposited on flood -plains and along valley floors." The upper unit of the young alluvial floodplain deposits (Qya2) are bound by older young alluvial flood plain deposits I � 5 Page 787 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 LEGEND: Qls Landslide Deposits (Holocene and Pliestocene) QVa Young Alluvial Flood -Plain Deposits, undivided (Holocene to )y Young Alluvial Flood -Plain Deposits, Unit 1 Qyax Young Alluvial Flood -Plain Deposits, Unit 2 Qyc Young Colluvial Deposits (Holocene to late Pliestocene) ?t� s Serpentinized Ultramafic Rocks (Jurassic) - Franciscan Melange (Cretaceous to Jurassic) APPROXIMATE PRELIMINARY PROJECT ALIGNMENT N , l f � ; 1I1 Qya2 Base Map: Wiegers, Mark O. 2010. Geologic Map of the San Luis Obispo 7.5' Quadrangle, San Luis Obispo, California Figure 3: Geologic Map (Wiegers 2010) North J y t 0 2,000 r feet (Qya1). Franciscan Melange (KJfm) is expected to underlie the alluvium at the project site. The Franciscan Melange and serpentine (Jos) are mapped by Wiegers on hillsides northeast and northwest of the project site. Wiegers describes the Franciscan Melange as a "chaotic mixture of fragmented rock masses embedded in a penetratively sheared matrix of argillite and crushed metasandstone" with "individual rock masses contained in the matrix range from less than a meter to kilometers in scale." Mapped outcrops of greywacke sandstone, serpentine, and melange are common within the Franciscan melange. Geologic structure in the region is generally characterized by a series of northwest trending faults and folds; such as predominant Quaternary faulting along the Los Osos Fault Zone, Edna Fault, Cambria Fault, and the Oceanic (West Huasna) Fault systems mapped approximately 1 miles southwest, 2 miles southwest, 3 miles northeast, and 5 miles respectively northeast of the project site (USGS 2023). VA 6 Page 788 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 4.2 SURFACE CONDITIONS 4.2.1 TERRAIN AND TOPOGRAPHY The project site is located along the San Luis Obispo Creek Valley in the City of San Luis Obispo. The layout of the existing site and project limits is shown on Plate 1. Prado Road currently has an at grade interchange with US 101 consisting of only northbound on- and off -ramps. Existing terrain along the project alignment is generally flat ground sloping easterly toward San Luis Obispo Creek at average grades of approximately 0.5 to 1 percent. Existing land use generally consists of commercial development within Madonna Plaza to the northwest of the proposed interchange. Land use along the west approach to the proposed interchange is currently being converted from agricultural row crops to mixed residential and commercial development. Land use northeast of the proposed interchange is mixed business, commercial, residential, and agricultural development. Existing developments along the north side of Prado Road include social services, charging stations, and a transit facility. The City of San Luis Obispo's Water Reclamation Facility is located on the south side of Prado Road and southeast of the proposed interchange. 4.2.2 SURFACE WATER AND DRAINAGE San Luis Obispo Creek flows southerly along the easterly side of US 101. The creek channel is generally incised with a thalweg elevation about 20 feet below the adjacent grades. The creek crosses beneath the Prado Road Bridge approximately 1,000 feet east of US 101. The creek meanders and runs alongside of the existing Caltrans right-of-way fence for about 200 to 300 feet ahead of the northbound off -ramp to Madonna Road, and adjacent to the proposed auxiliary lane alignment. 4.2.3 EXISTING FACILITY The existing US 101 and roadway improvements were generally made near or just above previous site grades. Existing embankment fills along US 101 generally appear to be less than about 5 feet high. Prado Road is generally an at -grade street with intermittent curb, gutter and sidewalks. The streets and US 101 are paved with asphalt pavement. The existing pavements along Prado Road are generally in poor condition with areas of severe fatigue cracking. The pavements along the northbound ramps and US 101 are generally in fair to good condition with areas of light raveling of the pavement surface and along cold joints, and areas with low severity longitudinal cracks in the wheel paths. 4.2.4 EXISTING UTILITIES Existing utilities generally consist of buried pipelines and services, as well as overhead power and utility services along Prado Road, along Elks Lane, and that cross US 101 near the proposed interchange. High voltage overhead power transmission lines cross US 101 above the existing northbound on -ramp. Other utilities include buried pipelines that cross underneath US 101 and likely I� 7 Page 789 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 run along the Madonna Road Interchange. Location and mapping of existing utilities is not within scope of the geotechnical services for this report 4.3 SUBSURFACE CONDITIONS The predominant geologic units encountered in previous studies (see Section 3.2 of this report) are surficial units of existing artificial fill and alluvium that overly Franciscan Bedrock at some depth below the project site. The approximate locations of previous borings are shown on Plate 1. Generalized north -south and east -west subsurface profiles based on those previous data are shown on Plates 2 and 3. A general description of the units shown on the profile are summarized below. Utilities were discussed in the previous section of this report. Artificial Fill (Af). Artificial fill is generally present along the existing roadways, developed areas in association with existing pavements, road embankments, and utilities. The existing fills within the proposed roadway areas are generally expected to be less than about 5 feet thick. The fill is likely to be derived from clayey soil associated with local borrow sources, with the exception of select material that could have been used as fill for the existing pavement and utility trench backfills. Alluvium (Qya). Young alluvium was encountered in most of the explorations at the ground surface or underlying existing fill and pavement materials. The young alluvium encountered is interpreted to extend to depths of approximately 30 to 40 feet below the existing ground surface. This unit consisted of two predominant subunits (Qyal and Qyaz) that were mainly differentiated based on their consistency. The young alluvium was underlain by older alluvium in most of the explorations. Qyal. This subunit consisted of predominantly soft to hard clay and sandy clay. The unit was locally interbedded with layers and lenses of loose to medium dense clayey sand and clayey gravel. The unit appears to be associated with desiccated and moderately over consolidated clayey soil near or above the groundwater table. This subunit is generally considered to be the upper zone of young alluvial deposits described by Wiegers (2010). Qyaz. This subunit consisted of predominantly soft to medium stiff clay with varying amounts of sand and gravel with thin interbedded layers of loose to medium dense sand with varying amounts of gravel. This unit appears to be associated with lightly to moderately over consolidated clayey soil that is most often below the groundwater table. Historically this unit is prone to consolidation settlement. This subunit is generally considered to be the lower zone of young alluvial deposits described by Wiegers (2010). Older Alluvium (Qoa). Older alluvium was encountered below the upper units in most of the explorations that were deep enough to penetrate the young alluvium. The older alluvium was I� 8 Page 790 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 typically encountered at depths ranging between about 40 and 60 feet below the ground surface but maybe encountered at shallower depths below Prado Road closer to San Luis Obispo Creek. The unit was a mixture of sediments that were composed of medium dense to very dense silty sand, clayey sand and gravel, and very hard to stiff clay and sandy clay. The extents and composition of fine- grained, sand and gravel sediments varied between explorations. The older alluvium was underlain by Franciscan melange bedrock where penetrated. Franciscan Melange (KJfm/KJfmv). Franciscan melange was encountered below the alluvium and older alluvium and is the predominant geologic unit that underlies all other sediments in the project vicinity. Borings and CPT soundings from the explorations commonly met refusal near the bedrock surface or shallow depths into it. The depth to bedrock is estimated to be about 60 feet below the ground surface near the center of the proposed interchange. The melange primarily consisted of blocks of moderately hard to hard graywacke in a matrix of soft intensely fractured and sheared claystone (KJfm). Borings by Yeh (2025) for the Prado Road Bridge project were cored to a depth of about 100 feet, or approximately 60 feet into the Franciscan melange bedrock. S. GROUNDWATER Groundwater conditions in the vicinity of the project site are generally influenced by stream flow levels in San Luis Obispo Creek, and the depth to bedrock below the site. Groundwater was encountered at various depths and locations in previous studies. A summary of groundwater measurements reported from the previous studies is presented in Table 2. Table 2 includes borings presented in referenced studies (see Section 3.2) that encountered groundwater. Data reported in metric units were converted to imperial units before listing them in Table 2. Table 2: Summary of Groundwater Measurements I9 N Page 791 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 Ground Groundwater Measurements Boring No. Study Surface El. Depth Elevation Location/Project (feet) (feet) (feet) Date Measured Notes B-2 Parikh (2002) 135.5 17.5 118.0 6/27/200 East abutment vicinity Prado Rd-US101 OC B-402, 403 111.1- Drilled in Prado Road between US Fugro (2002) 136.1 24.5-25.0 2/5-8/2002 111.E 101 and Prado Road Bridge SLO Water Reuse B-13 Ground elevations are not WSC (2022) 152 22 130 3/24/2022 reported and are estimated from Madonna Rd Google Earth at east of OC 35.267142-, - 120.672137- B-17 Ground elevations are not WSC (2022) 138 25 113 6/29/2022 reported and are estimated from US101 SB Onramp at Google Earth at Madonna Rd 35.263172°, - 120.674106° About 600 feet south of western terminus of project B-18R Ground elevations are not WSC (2022) 120 9 111 6/27/2022 reported and are estimated from Froom Ranch Way Google Earth at 35.256650-, - 120.678056- Ground elevations are not B 20 reported and are estimated from WSC (2022) 129 18 111 3/22/2022 Google Earth at El Mercado 35.260627°, - 120.675801° Ground elevations are not B 21 reported and are estimated from WSC (2022) 130 13 117 3/23/2022 El Mercado Google Earth at 35.259395-, - 120.674163- Ground elevations are not B 22 reported and are estimated from WSC (2022) 125 30 95 3/24/2022 Google Earth at Prado Rd 35.256498', - 120.673503' Ground elevations are not B 23 reported and are estimated from WSC (2022) 128 20 118 3/25/2022 Google Earth at Prado Rd 35.255653°, - 120.671779° Ground elevations are not B 24 reported and are estimated from WSC (2022) 130 16 114 3/31/2022 Prado Rd Google Earth at 35.255172°, - 120.670586° VA Page 792 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 San Luis Obispo Creek flows southerly along the eastern side of US 101. The channel of San Luis Obispo Creek is incised with a thalweg elevation that is about 20 feet below adjacent grades. Groundwater conditions and gradients generally appear to follow San Luis Obispo Creek with the shallowest depths to groundwater of about 10 feet in explorations performed on the west approach to the proposed Prado Road Overcrossing, and to depths of about 15 to 20 feet in explorations performed on the east approach to the proposed overcrossing. Groundwater levels and soil moisture conditions will vary seasonally and in association with changes in precipitation, runoff, irrigation, pumping, and other factors. Additionally, groundwater and the control of groundwater have been an issue on projects in the vicinity such as the Laguna Lift Station (Fugro 1999) and the SLO WRF Water Reuse project (Fugro 2002). There are reported difficulties associated with dewatering of excavations as well as impacts to adjacent structures as a result of dewatering. 6. SCOUR DATA Earth retaining structures (ERS) proposed for the west side and east side approaches and the northbound off- and on -ramps are not located adjacent to an existing watercourse. However, the site is within the 100-year flood plain and will be subject to episodic flooding. Additional data and analyses are needed to evaluate whether there is potential for flooding and scour at embankments and ERS in these areas. The northernmost part of the proposed auxiliary lane on US 101 between Prado Road and Madonna Road is adjacent to San Luis Obispo Creek and close to the top of the creek bank and right of way. The creekbank in this area was stabilized with rock slope protection after storms in 2023. The auxiliary lane will be supported by widening the existing embankment toward the creek. Scour test data were I � Page 793 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 not available from the previous studies reviewed for this report. Additional subsurface information and analyses are needed to evaluate whether there is a potential for scour to occur at this location. 7. CORROSION EVALUATION Soil within the project area is not considered corrosive based on laboratory data from previous studies in the site vicinity (Yeh 2025). Corrosion testing should be performed on soil and water samples obtained from the site -specific field exploration program for the final design of the project. The project site is approximately 6 miles from the Pacific Ocean; therefore, it is not considered to be within a marine environment based on the Caltrans (2021b) Corrosion Guidelines. 8. SEISMIC INFORMATION 8.1 GROUND MOTION HAZARD 8.1.1 GROUND MOTION PARAMETERS Seismic data were generated using the selected site parameters and ARS Online (Caltrans 2025b) to estimate ground motion parameters in accordance with Appendix B of the Caltrans (2025a) Seismic Design Criteria (SDC) and the Caltrans (2021a) Geotechnical Manual — Design Acceleration Response Spectrum. The SDC defines the Safety Evaluation Earthquake (SEE) as an earthquake having a 975- year-return period and is used for geotechnical design for slopes, retaining walls, bridges, and other structures. Seismic data were generated for site conditions using the location of the proposed overcrossing. The shear wave velocity for the project site was estimated from the seismic CPT data obtained for this project and the Yeh (2025) report prepared for the Prado Bridge Replacement Project. The Yeh (2025) data were used because the geologic conditions appear to be similar to those at the project site based on previous data (Parikh 2002). Table 3 presents the preliminary seismic data used in Yeh's preliminary analyses. These data provide the basis for estimating seismic parameters for seismic slope stability analyses and input for analyzing liquefaction hazards. Seismic data will be generated for specific structure and point of analyses as the project design progresses and geotechnical data are collected for those improvements. The preliminary design response spectrum estimated for the SEE is presented in Figure 4. I � Page 794 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 Table 3: Recommended Ground Motion Parameters for Preliminary Geotechnical Design 1.4 1.2 0.2 Is \ I 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Period, T (sec) — - Design Response Spectrum AIRS Online: V 4.0 Mean Magnitude: 7.0505 at 25.37 km Spectral Damping: 5 percent O Peak Ground Accleration = 0.39g Latitude: 35.2569 degrees Longitude:-120.6748 degrees Vs3c: 320 meters/second Figure 4: Preliminary ARS Curve IAPage 795 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 The Caltrans (2025a) Seismic Design Criteria notes that a site -specific ground response analysis is required for sites that include any of the following criteria: • The estimated shear wave velocity in the upper 100 feet (or 30 meters) of the site, vs30, is less than 180 meters per second; • The soil profile contains one or more layers that are at least 5 feet thick which have a shear wave velocity less than 120 meters per second; • The site contains soil that has a potential for strength loss or volume change during seismic loading including liquefiable, sensitive clay, or collapsible soil; • The site contains one or more layers of peat and/or highly organic clay which has a thickness of at least 10 feet; • The site contains a layer of highly plastic clay (with a plastic index, PI, greater than 75) which has a thickness of at least 25 feet; and/or • The site contains a layer of soft to medium stiff clay (with an undrained shear strength, su, less than 1,000 pounds per square foot). Layers of sand encountered within the older alluvium are considered potentially liquefiable, as discussed in Section 8.2.2. The Caltrans (2022a) Geotechnical Manual forSite-Specific Dynamic Ground Response Analysis also notes that for sites considered potentially susceptible to liquefaction, a site -specific analysis is not required if any of these conditions are applicable: • The bridge structure is single -span; • The fundamental period of vibration of the bridge structure is less than or equal to 0.5 second; • Only the surficial soil layer is considered potentially liquefiable; • The total thickness of all liquefiable soil layers (excluding the surficial layer) is less than or equal to 5 feet. The potentially liquefiable soil is within a unit preliminarily mapped as older alluvium based on the previous studies and CPTs performed by Yeh. While older alluvial deposits (Pleistocene age) are typically not considered susceptible to liquefaction due to their age (Caltrans 2020a), additional exploration and evaluation should be performed in future phases of design to whether liquefaction will be a design constraint. A site -specific dynamic ground response analysis may be required for design, in accordance with Caltrans Seismic Design Criteria. The Caltrans Seismic Design Criteria notes that for sites requiring a site -specific ground response analysis, that "the design spectral acceleration at any period shall not I � Page 796 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 be taken less than 80% of the design spectrum obtained from the 2023 USGS Hazard Model with a vs30 =180 m/sec."The design ARS will be provided after the wall type alternatives are selected, additional boring data are available for the site following drilling for the project, and a site -specific ground response analysis is performed (if required). 8.1.2 SEISMIC SLOPE STABILITY PARAMETERS The preliminary horizontal coefficients of ground acceleration (kn) for the proposed structures were estimated for the design earthquake using procedures described in the FHWA LRFD Seismic Analysis and Design of Transportation Features and Structural Foundations Reference Manual and referenced in Section A11.5.2 of the AASHTO (2024) LRFD Bridge Design Specifications. The procedures generally consider the design earthquake, duration, and a tolerable seismic displacement of up to 2 inches. The estimated pseudostatic coefficient (kn) for the design earthquake is shown in Table 4 and should be used for the preliminary design of abutments and retaining walls. Table 4: Recommended Horizontal Pseudostatic Coefficient for Preliminary Design 8.2 OTHER SEISMIC HAZARDS 8.2.1 SURFACE FAULT RUPTURE The project site is not within an Alquist—Priolo Earthquake Fault Zone and is not within 1,000 feet of an unzoned Holocene mapped fault. Fault rupture does not need to be considered in the design of the interchange improvements per Caltrans Geotechnical Manual - Fault Rupture (Caltrans 2022b). 8.2.2 LIQUEFACTION Liquefiable soil conditions are generally associated with loose to medium dense sand that is below the groundwater table at the time of an earthquake. Older alluvium consisting of loose to medium sand deposits were encountered below the groundwater table in selected previous explorations and recent CPT soundings. The younger alluvium previously encountered in the vicinity of the proposed overcrossing (Parikh 2002) generally consisted of stiff or dense clay and silt sediments that would not be considered vulnerable to liquefaction. Medium dense layers of sand which are potentially liquefiable were encountered at depths of 44 to 55 feet below the ground surface in the older alluvium in CPT soundings advanced by WSC (2022) and CPT soundings performed for this project. A summary of the liquefaction analysis using Cliq ®' 15 Page 797 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 (Geologismiki 2025) is included in Appendix A. Liquefiable materials are not likely to impact roadways or surface improvements (other than those adjacent to San Luis Obispo Creek near Madonna Road) but could have an impact on deep foundations for the project. While older alluvial deposits (Pleistocene age) are typically not considered susceptible to liquefaction due to their age (Caltrans 2020a), additional exploration and evaluation should be performed in future phases of design to ascertain whether liquefaction will be a design constraint. 8.2.3 SEISMICALLY INDUCED GROUND SETTLEMENTS Seismically induced settlement of up to % inch was estimated based on analyses using the CPT results and Cliq (Geologismiki 2025). As a result of the depth of the potentially liquefiable materials, the potential for seismically induced total and differential ground settlement to impact surface improvements at the proposed overcrossing location is considered low. 8.2.4 LIQUEFACTION -INDUCED LATERAL SPREADING Liquefaction -induced lateral spreading could be a design consideration at the north end of the proposed auxiliary lane. San Luis Obispo Creek runs along the current right of way in this vicinity with steep banks and an incised channel that is about 20 feet below the existing grade on US 101. The previous data are not sufficient to evaluate the potential for liquefaction -induced lateral spreading to impact the auxiliary lane. The potential for liquefaction and liquefaction -induced lateral spreading in this area should be assessed in association with the future phases of geotechnical study and field exploration. 8.2.5 SEISMIC SLOPE INSTABILITY Slope instability resulting from liquefaction and seismic shaking can impose loads on a structure that need to be estimated and resisted by the foundations according to Caltrans design guidelines, depending on the extent and severity of liquefaction. The horizontal coefficient of ground acceleration (kn) presented in Section 8.1.2 should be used for preliminary design of ERS under seismic loading. There is a potential that liquefaction induced lateral spreading will need to be considered for design of the auxiliary lane ERS as discussed in the previous section of this report. 9. PRELIMINARY GEOTECHNICAL RECOMMENDATIONS 9.1 PRELIMINARY GEOTECHNICAL RECOMMENDATIONS FOR EARTH RETAINING STRUCTURES (ERS) The project will include ERS for the west side and east side approaches on Prado Road, the northbound off- and on -ramps on US 101, and an auxiliary lane on US 101 between Prado Road and Madonna Road (see Table 1). The proposed retaining structures will likely be fill -type walls with proposed maximum wall design heights between approximately 5 and 20 feet and proposed wall lengths from approximately 160 to 1531 feet. Design vertical and lateral surcharge loads on the IF 16 Ai Page 798 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 retaining structures will include vehicle traffic associated with the interchange and roadway improvements. ERS alternatives considered for design include conventional retaining walls (semi -gravity), mechanically stabilized embankments, and modified conventional retaining walls supported on deep foundations. Considerations for design of ERS should include: • Bearing or axial resistance, overturning, as well as sliding or lateral resistance of the wall foundations (depending on the foundation type); • Initial and post construction settlement and wall deflection tolerances; • Anchor pullout resistance (if applicable); • Scour (if applicable); • Slope stability and foundation setback distance; • Seismic stability and impact from seismic related hazards such as liquefaction and lateral spreading; • Surface and subsurface drainage systems; and • Construction considerations such as those for footing or pile excavation, pile drivability, and anchor excavation, as well as those associated with excavation limits and spatial constraints related to existing structures, existing utilities, and/or traffic staging. The following are key geotechnical factors that should be considered in the selection of ERS types for design: • The subsurface conditions generally consist of the units of younger and older alluvium overlying Franciscan melange bedrock, as described in Section 4.3. • Groundwater at its shallowest depth was encountered at about 10 feet below the existing ground surface near the west side approach to the proposed overcrossing and generally ranged from approximately 10 to 20 feet below the existing ground surface in the ERS locations. The depth to groundwater varied by proposed ERS location and proximity to San Luis Obispo Creek. ERS foundation and embankment design will need to consider the potential for relatively shallow groundwater conditions. • Layers of lightly to moderately over -consolidated alluvium were encountered near and below the groundwater table, generally from the ground surface to depths of 30 to 40 feet below the ground surface. This unit consists predominantly of soft to medium stiff clay that is considered compressible and may be subject to long-term consolidation type settlement, depending on foundation and embankment loads that will exceed existing conditions. ERS foundation and embankment design will need to consider the bearing resistance of the clay 1"IrA 17 Page 799 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 foundation soil and the potential for long-term, post -construction settlement due to structure loads and the weight of new embankments. Further exploration, testing, and characterization of the alluvium are needed to characterize the strength and compressibility of the foundation soils. • Potentially liquefiable layers of loose to medium dense sandy alluvium were generally encountered at depths of 44 to 55 feet below existing site grades at the proposed overcrossing location during previous explorations and in CPT soundings performed for this project. Special recommendations that could be needed for ERS design to address liquefaction include site -specific design response spectra, seismic settlement, downdrag loads on piles, loss of lateral foundation support, and loads on retaining walls and foundations due to slope instability or lateral spreading (Caltrans 2024c). Due to the depth of the potentially liquefiable materials, the amount of estimated seismic settlement and impact to surface improvements such as shallow foundations at the proposed overcrossing location is considered low (see Section 9.2.3). • San Luis Obispo Creek runs along about 500 feet of the auxiliary lane south of Madonna Road. The creek banks are steep in this vicinity, and an incised channel exists about 20 feet below the existing grade for US 101. Geometric design of this area is in development. If the embankment is widened or the edge of the road approaches the top of creekbank, there could be potential for flooding, slope instability, scour, and liquefaction -induced lateral spreading to impact ERS design at this location, if needed. • The top of the Franciscan melange bedrock was encountered at approximately 60 feet below the ground surface at the proposed overcrossing location but will vary by retaining wall location. • Potentially contaminated soil and groundwater has been reported at the site. A plume of Tetrachloroethylene (PCE) was documented by WSC (2022) in the site vicinity. The PCE was present within the alluvium and older alluvium from approximately 20 feet below the ground surface to approximately the contact with the Franciscan melange bedrock. The presence of contaminated soil and ground could require special handling and disposal during construction of drilled deep foundations or other types of excavation. • Retaining wall foundations and backfill material could be submerged or partially submerged due to the potential for flooding at the proposed ERS locations. Retaining wall foundation and embankment design will need to consider the potential for uplift pressure on foundations, reduced support in the foundation soil, the potential for scour (if any) to impact the foundations, and the potential for increased lateral earth pressure on walls due to flooding. • There will be limited opportunity for excavation that would produce borrow in sufficient quantities for embankment construction and structure backfill for retaining walls. The existing 1APage 800 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 soil is predominantly clayey and is not considered suitable for reuse as select material for retaining wall backfill. The project will need import soil for use as backfill for retaining walls and likely most of the embankments. • The soils encountered were not considered corrosive based on previous laboratory data from previous studies in the site vicinity. Testing for corrosion potential should be performed for the final Foundation Report. The project site is not considered a marine environment based on Caltrans (2021b) guidelines. Discussions of each proposed ERS alternative being considered and the recommended ERS types for preliminary design are presented in the following sections. 9.1.1 CONVENTIONAL RETAINING WALLS Conventional retaining walls are typically used for fill -type applications and include retaining walls (Standard Plan walls, Caltrans 2024b) as defined in the Caltrans (2024e) Geotechnical Manual — ERS Type Selection and the Caltrans (2019) Amendments to the AASHTO (2017) LRFD Bridge Design Specifications. Conventional semi -gravity retaining walls consist of cast -in -place reinforced concrete walls of various heights supported by spread footing foundations and with varying backfill slope grades. Anticipated spread footing excavations would likely expose soft to hard clay and sandy clay of the younger alluvium encountered in previous explorations. Groundwater was encountered at about 10 feet or deeper below the existing ground surface for the proposed ERS locations and would likely be below the bottom of the proposed wall footings based on the anticipated wall heights. Benefits of the use of conventional retaining walls as an ERS alternative would include: • Conventional retaining walls are a common ERS type structure along state highways and may introduce potential reduced construction costs if the walls can be constructed in the dry without shoring, ground modification, or dewatering; • Specialty contractors are not typically required for construction; • Concrete traffic barriers can be incorporated into the design of these types of ERS; and • Lightweight fill may be used as backfill material behind conventional retaining walls to reduce the potential for settlement and improve stability by reducing active pressure and decreasing foundation stresses. Constraints and considerations that could adversely impact the cost and feasibility of conventional retaining walls include: • Standard cast -in -place concrete walls are generally not suited to tolerate post -construction settlement of more than 1 or 2 inches. Based on subsurface information from previous 19 )"IrA Page 801 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 studies, the foundation support soil for conventional retaining walls more than about 5 feet high could include clay layers prone to long-term post -construction settlement and consolidation. Therefore, pre -loading, settlement waiting periods, lightweight fill backfill, or ground modification could be required for conventional retaining walls to limit anticipated vertical displacement or support wall loading. Pre -loading or surcharging would need to be performed in advance of the retaining wall construction to limit the estimated post - construction settlement to within tolerable limits. Fill for pre -loading would need to be removed prior to wall construction. The estimated post -construction total and/or differential settlement could exceed tolerable service limits for spread footing foundations; • The ERS proposed for this project have maximum wall heights that vary between approximately 5 and 20 feet. Standard plan conventional retaining walls can be designed to these heights without modification. However, excavation to improve the foundation support condition below the retaining wall relative to bearing resistance and settlement may be needed depending on subsurface conditions at the specific ERS locations; • Deep foundation systems are typically needed to support conventional retaining walls for sites where shallow subsurface soil is not suitable to support the foundation loads; and • Conventional retaining walls would require longer construction schedules (compared to MSE walls) due to the time needed for concrete curing. Conventional retaining walls are considered a feasible ERS type for preliminary design for the proposed ERS for the project, but could involve surcharging, settlement waiting periods, or ground improvement to reduce the estimated settlement to within tolerable limits before construction of the new retaining walls. Lightweight fill, wick drains, or ground modification could also be used to reduce the estimated settlement to within tolerable limits and/or the length of the settlement waiting period during construction. 9.1.2 MECHANICALLY STABILIZED EMBANKMENT (MSE) WALLS Mechanically stabilized embankment (MSE) walls consist of tensile reinforcement within a soil backfill, as defined in the Caltrans (2024e) Geotechnical Manual — ERS Type Selection and the Caltrans (2019a) Amendments to the AASHTO (2017) LRFD Bridge Design Specifications. MSE are best suited for fill -type applications but can be used in cut conditions with excavation. The tensile reinforcements can be either metallic (strip or grid type) or geosynthetic (geotextile, strip, or geogrid type). MSE facing units are typically precast concrete panels or alternatively modular blocks, wire mesh cribs, and other type units. Caltrans standard MSE include standardized precast concrete panels and wire mesh mat tensile reinforcements. MSE that include non -standardized facing units or tensile reinforcements and/or consider design parameters, load cases, or wall geometry outside of those IF 20 Ai Page 802 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 presented in Caltrans (2021c) are considered non-standard. Standard MSE walls have a maximum vertical height of 50 feet and face inclinations of 70 degrees to vertical (Caltrans 2021c). Benefits of the use of MSE as an ERS alternative would include: • MSE walls have been used on highway systems in California for approach fills and other applications; • MSE walls can tolerate greater total and differential settlements compared to conventional retaining walls if the wall can be designed to limit the potential for outward rotation of the wall face; • Lightweight fill may be used as partial or full backfill material in MSE to reduce the potential for settlement and improve stability by reducing active pressure and decreasing foundation stresses; and • MSE facing units can be manufactured with different patterns, colors, or artwork for aesthetic purposes. Constraints and considerations that could adversely impact the cost and feasibility of MSE walls include: • MSE walls may likely need to be non-standard designs based on the soft, compressible soil encountered in the previous studies and CPT soundings performed at the project site; • Based on subsurface information from previous studies, the foundation support soil for MSE walls more than about 5 feet high could include clay layers prone to long-term post - construction settlement and consolidation. Therefore, pre -loading, settlement waiting periods, lightweight fill backfill, or ground modification could be required for MSE walls to limit anticipated vertical displacement or support wall loading. Pre -loading or surcharging would need to be performed in advance of the retaining wall construction to limit the estimated post -construction settlement to within tolerable limits. Fill for pre -loading would need to be removed prior to wall construction. The estimated post -construction total and/or differential settlement could exceed tolerable service limits for spread footing foundations; • Temporary excavations for MSE wall construction are typically two to three feet wider than the longest reinforcing strips. Typical reinforcing strips range in length from 0.7H to 1.2H depending on the loading conditions. Excavation widths can often interfere with adjacent travel lanes and potentially require temporary shoring to construct the walls. Space constraints for locations adjacent to existing facilities would likely be a challenge to provide sufficient width to place reinforcing strips while maintaining lanes of open traffic; IF 21 AA Page 803 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 • MSE foundations and facing units could be submerged or partially submerged due to the potential for flooding at the proposed ERS locations. Gravel backfill, drainage, and scour protection should be provided if the wall will be exposed to stream flow. • Incorporating concrete traffic barriers or guardrail along the top of MSE walls requires special design considerations; and • Soft foundation soils prone to settlement or creep could increase the potential for overturning and increased rotational stresses for MSE walls. Overstressed reinforcements can result in wall failure or collapse. Local and global MSE wall stability, bearing resistance, and settlement analyses should consider the foundation support conditions. Mechanically stabilized embankment walls are considered a feasible ERS type for preliminary design for the proposed ERS for the project. MSE walls can be designed to tolerate some settlement that may be associated with consolidation of the alluvial foundation support soils. 9.1.3 MODIFIED CONVENTIONAL RETAINING WALLS SUPPORTED ON DEEP FOUNDATIONS Modified conventional retaining walls supported on deep foundations typically consist of reinforced concrete cantilever walls of various proportions supported by either driven piles or cast -in -drilled - hole (CIDH) piles. Caltrans Standard Plan conventional retaining walls (see Section 10.1.1) can be modified to allow for a pile -supported retaining wall alternative. An existing conventional retaining wall near the overcrossing structure at US 101 and Los Osos Valley Road is supported on deep foundations that bear in similar foundation materials (MNS 2015). Benefits of the use of modified conventional retaining walls supported on deep foundations as an ERS alternative would include: • Conventional retaining walls are a common ERS type structure and may introduce potential reduced construction costs if the walls and deep foundations can be constructed in the dry without excessive shoring, ground modification, or dewatering; • Modified conventional retaining walls typically have smaller footing/pile cap sizes compared to footings for non -modified conventional retaining walls, therefore requiring a smaller excavation footprint; • Concrete traffic barriers can be incorporated into the design of these types of ERS; and • Supporting a conventional retaining wall on deep foundations would likely reduce post construction settlement to within tolerable limits. Deep foundations for modified conventional retaining walls could be designed to bear in the underlying older alluvium or bedrock and could be designed for settlement -induced downdrag, if needed. 22 11"r4l Page 804 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 Constraints and considerations that could adversely impact the cost and feasibility of modified conventional retaining walls supported on deep foundations include: • Modified conventional retaining walls supported on driven pile foundations may include the following considerations: o Open-end pipe or H-piles may run during driving, resulting in uncertain pile tip elevations and driving conditions during construction. Closed -end pipe or precast concrete piles are preferred and would help to control the pile tip elevation for design and construction. However, H-piles may be more cost effective and could be used provided there are provisions in the project specifications to account for the conditions noted above; o Pile driving will require specialty equipment and potentially cranes that can require a larger equipment footprint during construction; o Pile driving will generate noise. Pre -construction surveys of nearby businesses and residences, distress surveys, and noise and vibration monitoring may be needed for pile driving; and o Delays could occur if splicing of steel piles is needed due to requirements for inspection and testing of field welds as well as lead time for splice materials. Steel piles could be ordered to account for anticipated variances in pile tips and driving resistance requirements. • Modified conventional retaining walls supported on CIDH pile foundations may include the following considerations: o Wet methods (slurry displacement) would likely be needed to construct CIDH piles because of the groundwater conditions encountered in previous borings at the project site. CIDH piles should have a diameter of at least 2 feet for wet construction. Drill rigs used to construct CIDH piles can be equipped with temporary casings and other tooling to help support the shaft during drilling and advance the hole through soft ground, caving soil layers, and groundwater. Post -construction inspection and non- destructive testing of CIDH piles constructed in the wet is required by Caltrans (2024a) Standard Specifications. Anomalies are often identified that require delays, review of the design loads, and possible mitigation or pile replacements to address anomalies; o CIDH pile construction will involve cutting and slurry disposal that would likely encounter groundwater conditions and potentially contaminated soil (WSC 2022); o Tanks for slurry and spoils associated with wet -method CIDH pile construction can require a larger construction footprint compared to that required for driven pile construction; and JAPage 805 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 o CIDH piles with modified low vibration installation methods are more costly but are considered suitable for support of the ERS structure where the construction noise and vibration are a factor. • Modified conventional retaining walls supported on deep foundations would require longer construction schedules due to the time needed for concrete curing. Modified conventional retaining walls supported on deep foundations are considered a feasible ERS type for the proposed ERS for the project. Supporting the ERS on deep foundations would likely reduce the potential for post construction settlement. However, modified conventional retaining walls would be less tolerable to settlement -induced deflections compared to MSE walls. 9.1.4 RECOMMENDED EARTH RETAINING STRUCTURE (ERS) TYPES Mechanically Stabilized Embankment (MSE) walls are considered the preferred ERS alternative considering the geotechnical conditions and spatial constraints at the project site. MSE walls would likely need to be non-standard MSE designs based on the foundation conditions at the site and may require pre -loading and settlement monitoring periods or ground improvement to support the proposed walls. Pre -loading and settlement methods (with or without wick drains) would require placing fill and surcharge and then removing enough material to allow for construction of the MSE walls, which complicates the schedule and movement of materials. Use of ground improvements could be more effective. The MSE wall recommendation does not consider the potential for flooding at the west side and east side approaches. Additional data and analyses will be needed to evaluate the degree to which flooding may impact an MSE alternative in this area. Modified conventional retaining walls supported on deep foundations are also considered a feasible ERS alternative. However, modified walls would be less tolerable to differential settlement compared to MSE walls and may still require pre -loading and settlement monitoring periods or ground improvement to support the embankments supported by the walls. Both driven piles and drilled CIDH piles are considered suitable for support of the modified conventional retaining walls. An existing conventional retaining wall near the overcrossing structure at US 101 and Los Osos Valley Road was supported on driven piles in similar foundation materials (MNS 2015). 10.ADDITIONAL FIELD WORK AND LABORATORY TESTING Subsurface exploration, laboratory testing, and analyses should be performed in preparation of the Geotechnical Design Report (GDR), Foundation Reports for Earth Retaining Structures (FR for ERS) and Foundation Reports for Bridges (FR) for the project. The design -level field explorations will be checked and modified for the selected design alternatives. The future field exploration program will supplement the CPT soundings performed in July 2025 and include drilling vertical borings and 1"IrA 24 Page 806 of 1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 advancing additional CPT soundings at the proposed overcrossing and ramp structure supports, retaining wall locations (where applicable), pavement areas, infiltration basin areas, and proposed overhead sign structures. The types and numbers of tests may vary based on the results of the field exploration program. 11.LIMITATIONS Yeh prepared this report for Consor and their authorized agents only. It is not intended to address issues or conditions pertinent to other parties, projects or for other uses. This report is for preliminary planning purposes only and is not intended for use in final design or construction. The results of this study are preliminary and subject to change pending the results of our design -level field exploration and geotechnical evaluation. No services have been performed to evaluate environmental impacts, or the presence of hazardous or toxic materials. Site conditions will vary between points of observation or sampling, seasonally, and with time. The nature and extent of subsurface variations across the site may not become evident until excavation is performed. If during construction, fill, soil, or water conditions appear to be different from those described herein, Yeh should be advised and provided the opportunity to evaluate those conditions and provide additional recommendations, if necessary. 12.REFERENCES American Association of State Highway and Transportation Officials (AASHTO 2024), AASHTO LRFD Bridge Design Specifications, 101" Edition, issued 2024. American Association of State Highway and Transportation Officials (AASHTO 2017), AASHTO LRFD Bridge Design Specifications, St" Edition, issued 2017. California Department of Transportation (Caltrans 2025b), ARS Online, Version 4.0, Online Web Tool, https:Harsonline.dot.ca.gov/, accessed July 17, 2025. California Department of Transportation (Caltrans 2025a), Seismic Design Criteria, Version 2.1, Division of Engineering Services, Structures Design, issued January 2025. California Department of Transportation (Caltrans 2024e), Geotechnical Manual, ERS Type Selection, issued August 2024. California Department of Transportation (Caltrans 2024d), Geotechnical Manual, Non -Gravity Cantilever Earth Retaining Systems, issued February 2024. California Department of Transportation (Caltrans 2024c), Caltrans Geotechnical Manual, Geotechnical Seismic Design of Earth Retaining Systems, issued February 2024. California Department of Transportation (Caltrans 2024b), Standard Plans, issued 2024. I � Page 807 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS Project No. 223-400 US 101 at Prado Road Interchange Project December 23, 2025 California Department of Transportation (Caltrans 2024a), Standard Specifications, issued 2024. California Department of Transportation (Caltrans 2023). U.S. 101/Prado Road Interchange Project, on U.S. 101 in San Luis Obispo County, 05-SLO-101-PM 26.5-27.3, Project ID Number 0516000105, Initial Study with Proposed Mitigated Negative Declaration, dated January 2023. California Department of Transportation (Caltrans 2022b), Geotechnical Manual, Fault Rupture, Sacramento, California, issued October 2022. California Department of Transportation (Caltrans 2022a) Geotechnical Manual forSite-Specific Dynamic Ground Response Analysis, Sacramento, California, issued March 2022. California Department of Transportation (Caltrans 2021c), Geotechnical Manual, Mechanically Stabilized Embankment (Caltrans Pre -Designed), issued January 2021 California Department of Transportation (Caltrans 2021b), Corrosion Guidelines, Version 3.2, Division of Engineering Services, Structure Design, issued May 2021. California Department of Transportation (Caltrans 2021a), Geotechnical Manual, Design Acceleration Response Spectrum, Sacramento, California, issued January 2021. California Department of Transportation (Caltrans 2020b). Caltrans Geotechnical Manual, Liquefaction -Induced Downdrag, issued January 2020. California Department of Transportation (Caltrans 2020a). Caltrans Geotechnical Manual, Liquefaction Evaluation, issued January 2020. California Department of Transportation (Caltrans 2019), California Amendments to the AASHTO LRFD Bridge Design Specifications, 8th Edition, Sacramento, California, issued April 2019 with June 2024 addendums. California Department of Transportation (Caltrans 2005), Field Review Memorandum, 05-Og780K, 101-SLO-PM27.0/27.5, Auxiliary Lane, dated July 23, 2001. California Department of Transportation (Caltrans 1986), Pile Quantities and Driving Records, Bridge No. 49-185, dated October 2 to 10, 1986. California - Department of Public Works - Division of Highways (Caltrans 1963), Log of Test Borings, Madonna Road Overcrossing, Bridge No. 49-190, as -built sheet, dated January 8, 1963. California - Department of Public Works - Division of Highways (1962), Pile driving records, Bridge No. 49-190, dated October 1, 1962. California - Department of Public Works - Division of Highways (Caltrans 1961a), Pile driving records, Bridge No. 49-185, dated October 2 to December 4, 1961. I � Page 808 off1059 DRAFT Structure Preliminary Geotechnical Report - ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 California - Department of Public Works - Division of Highways (Caltrans 1961b), Log of Test Borings, Los Osos Road Overcrossing, Bridge No. 49-185, as -built sheet, dated December 12, 1961. Consor (2025b), Strip Map, provided via email December 5, 2025. Consor (2025a), Strip Map Profile, provided via email December 3, 2025. Dokken Engineering (Dokken 2009), Technical Memorandum, Seismic Evaluation, U.S. 101/Los Osos Valley Road Interchange Improvements Project, San Luis Obispo, California, dated January 22, 2009. Fugro West, Inc. (Fugro 2002), Geotechnical Report, City of San Luis Obispo Water Reuse Project, San Luis Obispo, California, Project No. 01-52-0721, consultant report prepared for Brown and Caldwell, dated April 2, 2002. Fugro West, Inc. (Fugro 1999), Geotechnical Engineering Report, Laguna Lift Station Force Main Upgrade and Replacement Project, San Luis Obispo, California, Project No. 99-42-0411, consultant report prepared for Brown and Caldwell, dated November 23, 1999. Geologismiki (Geologismiki 2025), Cliq Liquefaction Analyses Software v3.5.3.15, release date June 3, 2025. GeoResearch-Unocal (Unocal 1990), Site Investigative Report, Elks Lane and San Luis Obispo Creek, San Luis Obispo, California, dated April 16, 1990. GHD (2018), Project Study Report - Project Development Support (PSR-PDS) to Request Approval to Proceed to the Project Approval and Environmental Document Phase for a Locally Funded Project on Route 101 between 0.3-mile south of Prado Road and 0.2-mile south of Madonna Road Overcrossing, EA 05-1H640K, dated March 2018. MNS Engineers, Inc. (MNS 2015), Pile driving records and quantities, Bridge No. 49-185L, dated February 3 to 16, 2015. Parikh Consultants, Inc. (Parikh 2002), Log of Test Borings, Route 101/Prado Road Overcrossing, last revision dated November 15, 2002.Unites States Department of the Interior - United States Geological Survey (USGS 2023). Earthquake Hazards Program, Interactive Fault Map and Quaternary Fault and Fold Database of the United States, accessed December 27, 2023, https://www.usgs.gov/programs/earthquake-hazards/faults?qt- science_support_page_related_con=4#qt-science_support_page_related_con United States Department of Transportation - Federal Highway Administration (FHWA 2011), LRFD Seismic Analysis and Design of Transportation Geotechnical Features and Structural Foundations Reference Manual, Geotechnical Engineering Circular No. 2, NHI Course No. 130094, Publication No. FHWA-NHI-11-032. Page 809 off1059 DRAFT Structure Preliminary Geotechnical Report — ERS US 101 at Prado Road Interchange Project Project No. 223-400 December 23, 2025 Water Systems Consulting, Inc. (WSC 2022), Remedial Investigation Report, City of San Luis Obispo Tetrachloroethylene (PCE) Plume Characterization Project Summary, dated December 2022. Wiegers, Mark O. (Wiegers 2010) Geologic Map of the San Luis Obispo 7.5' Quadrangle, San Luis Obispo, California, scale 1:24,000. Yeh and Associates, Inc. (Yeh 2025), Foundation Report, Caltrans Bridge No. 49C0107, Prado Road Bridge Replacement at San Luis Obispo Creek, San Luis Obispo, California, Project No. 216-323, consultant report prepared for the Wallace Group/City of San Luis Obispo, dated November 25, 2025. 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H N O M W Z L >. __ - _________ ______CL 0 W N Z 0 O " -t---------------------- ----�------------- C W C; E o w N x C T ca 2 > / I N o UO MW C H ------ -L'--F----- n �J W u m x -----` I E g F 3 'v w m > C ---- - --- -------- N o a O! -6 I----'---'------- W z o ----°-------- ----------------- a -____•--------------- - ;' o c ED ..__--_•__- .___.,____.-___,, ______________ E 3 E E IS o o P N W i v c y o 1 N c — ---------0o m o a' U� a a E x m o w (1333) NOIIVA313 Page 813 of Mwe APPENDIX A - CPT LOGS AND LIQUEFACTION ANALYSES Page 814 of 1059 Ln M o W ?4 Q N a� o W O J V � LU N LL a N 0 E 0 U orn J c J = Q L U z z �' J Ol a 0 3 m W N L (n F�1 L7 W J � Q Z U Q W x LU a H iLi Z LU J U O L C LL E W 00 �-4 vo o O W N n tD 0 v � N m L) 0 O N V 10 W O N V t0 MON V 0 W O N V t0 W O N V lO W O N t t0 W O N 7 l0 W O M M M M V. 7 V T l.m m m m m t0 0 0 t0 tD I, (4d) 44daa 0 0 N 0 Ln O O 0 Ln 0 O N V 10 W O N V ID W O N 7 ID W O N 7 0 W O N 7 tO W O N 7 0 W O N R tO W O -. -i .--i .--i ti N N N N N M M M M M 7 7 7 7 7 M Ln M M M 0 t0 t0 t0 O N (41) 44daa O W �o 0 N O O N V to W 7 O N 7 I W O N 7 I W O N 7 ID W O N O W O N 7 IW O N N N N N M M M M M lfl In In In W ID tO 0 tO tD I, (44) 4jdaa O W w t0 c o_ u U LL N 0 O N 10 W O N T 10 W O N 7 tD W O N 7 t0 W O N 7 t0 W O N It ID W O N V ID W O - .ti .--i .--i ti N N N N N M M M M M 7 7 V V 7 In In Ln Ln Ln VD t0 0tO tD I, (4j) 4ldad O it 0 ........... M Q U C W = N can o d � 0Q o o O N t0 W O N V tD W O N 7 tD W O N t- t0 00 O N 7 tD W O N 7 0 W O N 7 tD W O M M M M M 7 7 7 7 t M Ln Ln M In 0 O 0 0 ID N (1j) 4;daa d N N O Lr N O N O M n C 0 v v m v U u O n W ce d a u 059 Page 815 of 02 m L, N o N LLI N N O rl o a N r, V LY w= LA C o rel N JV N ui o LL +� d n N V m 0 E 0 v m J c J = a (.j -o U z a J J Ol G 3 H m C7 3 C W d V% ce G7 t W FI J a z U O ul U [� \/ di p LU � a H W z H LLJ J U M 'DO N o O My D 0 v � N m 0 ON V tO M O N 7 tD M O N V lD M O N 7 l0 M O N V lD MON 7 \D M O N V lD M O N N N N N M M M M M V V V V V In m m Ill 10 ID lD 10 10 Il (11) 4lda4 0 u O G! d L R s O a c O r u LL a C N 0 LQ O O w C Ln 0 O O O N V iD M O N V tO M O N V ID M O N V kD M O N V kD M O N V %0 M O N V %0 M O N N N N N M M M M M V V V V V Ill Ill Ill M M ID o 0 O ID n (13) 4lda4 N O ON V 10 M O N 7 lO M O N V ID M O N 7 lD M O N 7 ID MON 7 ID M O N V l0 M o N N N N N M M M M M V V V Ill Ill m m m ID 0 0 lO lO h (41) 44da4 O - - - - O O N 7 iD CO O N 7 kD M O N V kD M O N 7 iO M O N 7 kD M O N V. tD M O N V 10 co O N N N N N M M M M M 7 V V 7 V Ill Ill Ill m Ill 0 lD 0 0 10 Il (4d) 44daa O S v V C m ul u+ C O U O N 7 i0 M O N 7 10 M O N 7 ID M O N t- 10 M O N V ID M O N V ID M O N V 10 M O M M M M 7 V 7 7 V Ill lIl In N In lD lD l0 10 10 n (4j) 44da4 v O N M 0 Q 0 0 C+i Lr N O N 7 .-I n C 0 0 +u m 0 u 0 0 n 0 3 0 O .i6 2 Q i G� 0 a@+ n m 'O D a C.J M rn O 0 N F U 059 Page 816 of 02 m L, N `4 LU N o N o a N � a� o LY C O � J U LY o m LLB n N 0 E 0 u v m J c J = a �j 73 U z p1 .. a J J Ol G 3 H m C7 3 C W d V% G7 t W FI J a z U O ul U [� \/ dS 0 WEI I u=, a Uri� H W zLLJ H FI J u O a c O r u LL a O 'Do vo o O 0 v D 0 v � N m 0 ON V tD M O N 7 tD M O N V lD M O N 7 lD M O N t tD O O N'Z�' lD M O N V tD M O N N N N N M M M M M V V V V V m m m 10 ID lD 10 10 I\ (11) 4lda4 0 C N 0 LQ o O w C Ln 0 O O O N V iD W O N V tD W O N V ID N O N V iD M O N V kD 00 O N V %D O O N V %0 m O N N N N N M M M M M V V V V V Ill m m m m ID O 0 O ID n (13) 41da4 O O N V to CO O N 7 to M O N V ID M O N 710 M O N 7 tD M O N 7 tD W O N V lD co O M M M M V V V V V Ill Ill m m m ID 0 0 ID ID h (41) 44da4 0 O O N 7 ID W O N 7 10 w O N V ID CO O N 7 i0 W O N 7 'D CO o N 7 10 M O N V 10 W O M M M M 1. V 7 7 7 Ill Ill lfl m Ill 0 lD 0 0 10 I� (4d) 44daa O N 7 iD CO O N 7 10 M O N 7 ID M O N t_ 10 M O N V ID w o N V ID M O N V ID M O M M M M 7 V 7 7 7 Ill Ill m N In lD lD l0 10 10 n (4j) 44da4 O v O N M 0 m Q 0 0 C+i Lr N O N 7 .-I n C 0 0 +u m 0 u 0 0 ru itf 0 0 N C O Q i G� 0 a@+ n m 'O D a C.J M rn O 0 N F u 059 Page 817 of O U v m J = J = a (.j -o U z a J J tT G 3 H m C7 3 C W d V% G7 t W FI J a z U O ul U [� \/ dS 0 UJEI Iu=, a Uri� H W zLLJ H FI J U — — 00 C o - - 75 - 7[5- 7[5- --- ,) y as ces as as 3 (D oc ces as ces as ces ws ns oo ,f6„ .i C • O L)c) 0 �.lcicl cl c5�.lcl L5 cl L) L)clv)oov)inv)o .+t W = s m N ca U) LO 0 O N V tD W O N 7 tD 00 O N V lD 00 O N 7 l0 W O N 7 ID W O N T lD W O N 7 tD W O .-I N N N N N M M M M M V V V V V M M to M Ill %D lD lD l0 toI� (11) 4jda4 0 C yJ N V -O O O a j D o Ill i v ¢ V) G1 O o I Z 3 o � o> .0 0 O O N V iD W O N V t0 W O N V ID W O N -;I-iD W O N V kD W O N V ID W O N V t0 W O .-I N N N N N M M M M M V V V V V Ill Ill Ill m m ID O 0 O ID n (13) 4Ida4 O 4j m O a.I V �L LL !i V c m -+ 2 c 0 U ON V 10 M O N 7 tO W O N VDWON 7 lD W O N 7 ID WON T ID W O N V ID W O M M M M V V V V V Ill Ill lfl Ill m 10 lD lD 10 10 h (41) 44da4 O N 7 iO W O N 7 10 W O N V 10 W O N 7 10 W O N 7 ID W O N T 10 W O N V 0 W O M M M M 7 I 7 7 7 Ill Ill lfl m m 0 lD 0 0 10 n (4d) 44daa Of O N 7 ID W O N 7 10 W O N 7 ID W O N'r 10 W O N 7 ID W O N 7 10 W O N 7 ID W O M M M M 7 V 7 7 7 Ill Ill m N In 10 lD lD 10 10 n (4j) 44da4 O v N M 0 V Q 00 IR O .-I C"i Lr N O N 7 .-I n C 0 0 +u m u 0 0 Q 0 N Id O O .0 2 ro i 0 a@+ n i6 'O D a U M N O 0 N F U 059 Page 818 of Yeh and Associates 1AYeh and Associates, Inc. https://www.yeh-eng.com ,._-techni,,W•6co14.1• Cmtstrt 6-Scr ,, Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-01 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance 6 --- --- 8------- -------- 10 -------------- 12 ------ ------- 14 ----- ------- 16 ----- ------- 18 ----- ------- 20 ...... ........ 22 ------ ........ 24--------- ti------------ 26 - 28 --------------.......- L 30-------- ------- 32 ------ -------- QJ 34 ------------------------- 36........ ........ 38 ---- ........ 40 ------- 42 -- ------- 44 -- ------- 46 --- ------- 48 ------- 50 --- --- 52 --- ------- 54 - ------- , 56 ' 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 CRR plot 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 0 200 400 0 2 4 6 8 10 1 2 3 4 0 qt (tsf) Rf (%) Ic (Robertson 1990) Mw=71/2, sigma'=1 atm base curve 0.8 0.7 0.6 u 0.5 0 0 0.4 Ln (V V) u_ 0.3 v U 0.2 0.1 0 1,000 QJ .N v 100 0 v c v a F v v to N E o` Z H/J JD AUGERM ------------- ag•earthgq} .. Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 FS Plot HANDAUGER �Jb 0.2 0.4 O.E 0 0.5 1 1.5 2 CRR & CSR Factor of safety Summary of liquefaction potential , I I I I I I I I I I I I I I I I I I 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction .... .... .... ..... �. 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Y0 C 5 N W.Ll m a m 3 rn CDE CD (u rn i N W ; V •C Vi 0 Q l L ��pp N 49 U1 V v C o N in o T W W 79 O w w N o m o Lm C Z Z co a 3C --+ O p O O C G1 _0 N w w — B C� O O m a C I C U c N 4j 2,CD /1 l0 f6 E 0 m y u o8�°S V C C C E O ISO W d 00 N Q O O U aJ 6 N M O Q Yeh and Associates 1AYeh and Associates, Inc. https://www.yeh-eng.com ,._-techni,,W•6co14.1• Cmtstrt 6-Scr ,, Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-02 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance Friction Ratio SBTn Plot CRR plot 0.8 0.7 0.6 u 0.5 0 0 0.4 aV Ln u_ 0.3 v U 0.2 0.1 0 5 10 15 20 25 30 35 40 45 50 55 60 Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based FS Plot 5 10 15 20 25 30 35 40 45 50 55 60 100 200 30( 0 2 4 6 8 10 1 2 3 4 0 0.2 0.4 O.E 0 0.5 1 1.5 2 qt (tsf) Rf (%) Ic (Robertson 1990) CRR & CSR Factor of safety Mw=71/2, sigma'=1 atm base curve Summary of liquefaction potential 5 10 15 20 25 30 35 40 45 50 55 60 1,000 QJ .N v 100 0 v c v a F v v to N E 0 Z 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction ��.., • Wo Liquefadtion Project file: C:\Users\jking\Yeh and Associates, Inc\223-400 Prado Road IC - General\3.2 CPT\223-400 Prado Road IC Liquefaction CPT-01 to 04. q age 826 of T059 A-12 of 32 fV O d V E ra uV d a H 7 O m s d m .O U) 41 O a m g -- --- -- ........ 6 ...... --em _ s ....... cfi..........�; r ea••;---; rrv-- -- ---fJ-S -- dtf- o2f .$ - d3 :.6:.6.6: .6 as de$d n :0 ; 00 (x) U ; cx 0 ; CX-)X_-X-XX-)c XX-) cx-)c-) C N O N 7 ID W O N 7 10 M O N V 7 10 W 'O N V 10 W 0 N N N N N M M M M M V V (lj) 4adaa J N 7 iD W O ti V t0 � O N N 'N0 OOO m m m m 0 cNY I-D M- R Di vg 5O C rq (13) 4adaa J N V .D W O V tD of O N 7 ID OJ O N V- CD N V 10 W O N T t0 OJ O N N N N N N M M M R �t �t ct �t In In lI1 LA LA t0 t0 (41) 4adaa .4- 10 W D N N IDW M M M M M 7 "V V w � � 14- to w lOD lND W 10 ti 00 M O1 fa o � O O � F 7 m U) M N O N c C N O �f0 s� C N r, o6'6 ■■❑ U ±' C T � � O O p a U c C N C A N � C �O N U in U 7'Ln D MEN 0 r y W U> N L C y0 v m m O V _N H {A ❑❑❑ O- T C O O p rn �o¢ o Z} }Ln ZZ U C o d D_ d D NJ O 'Q 6 cu r m U rn, O— N N •F D_ Y -p -p OJ O I L Y U J J M O Lr a N 0 C N O m a U O O W Q ^ N 7 rV mZZ 02 c m aao m OU N= W U 1 K mo23 o 01 .2 y j 3 (V O �= O T 0 Q i -Vi ZS M l L U) N C u� U N Eti 2 LA 49 Y Lp WW > N y Vvc 0 Ln o Ov1 T wLu T� w w N o m CDo p z z m r—CS fa � v Q � ac � rn Ln U O C C L w U V d 0 N ..E c u +� vOi U C V O p m Mr -I o E � YD3 LO o 22 (`i V C > y y > U a r.Rr npmrt0--f1 r��u. 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(in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance Friction Ratio SBTn Plot CRR plot I Y a QJ 0 0 ----- --- ---- 2 -- ---- --- 4 ..... .... 6 ---- ---- 8 --- ---- --- 10 ... ..... .... 12 ... ..... .... 14 -------------------- - 16 --- --- 18 -- ---- --- 20 .... ..... 22 ---- ----- ---- 30 ---- ----- ---- , 32 , , 36 -- ----- ---- 38 --- ---- --- 40 ... ..... .... 42 .. ...... 44 ----------- 46 --- --- 4g ..... .... 50 ..... .... 52 ---- --- 54 ---- --- 56 ---- --- 58 ---- --- 60 0.8 0.7 0.6 U 0.5 0 0 0.4 Ln (V V) u 0.3 T U 0.2 0.1 0 4 ----------- 6 ---- - -- 8 10 .. 12 .. 14 16 18 20 . 22 ' , 30 32 . 36 - ---- - 40 .. 46 ---- -- 48 . 50 52 54 ' 56 58 60------------ 100 200 0 2 4 6 8 10 1 2 3 4 0 qt (tsf) Rf (%) Ic (Robertson 1990) Mw=71/2, sigma'=1 atm base curve Liquefaction . ............... ....... ... --- J QI0 Wo Liquefadtion 1,000 QJ .N v 100 0 v c v a F U v to N E O Z Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based FS Plot 0.2 0.4 0.E 0 0.5 1 1.5 2 CRR & CSR Factor of safety Summary of liquefaction potential 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Project file: C:\Users\ king\Yeh and Associates, Inc\223-400 Prado Road IC - General\3.2 CPT\223-400 Prado Road IC Liquefaction CPT-01 to 04. q age 833 of 1`059 A-19 of 32 O �.--------------- __.___.___.___,___.___.>,.___.__�,> ___y =U)-4 --- N -Cos vn--. 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V lA O O m �p r-I E -O m Cl U o E m YD3 LO �0S',249 (`i V lT t O- Y y c U m � � -E-m O- .g O O N 7 'D 00 O N 7 IO M O N R tO W O N A M M 7 7 V 7 7 �O/1 lN/1 M ID 00 a rl rl rl rl rl N N N N N M MkD (1j) yjda4 x d V C _ fr O H � m O N 1-0 O L � V Q: A G1 CL L C � O O O y C s c V O N 7 t0 00 O O m O N tO w O N 7 'O w O N 7 t0 00 O N 7 tO 00 O N N N N N M M M M M 7 7 7 7 7 m In 1n � 1 10 O L L i O 0 W m w v � � V s S U M D N V, t0 w (U) y}daa N �r 'D w o O N 10 OD 0 .Ni ti „Oy w N N N N N M M M M V V V ID m �N+t v�i vOi 10 O 0 M O 61 N � O O Cl 0 CD N O c 'O a N N C0 0 Z} }In ZZ w w Li C o o 'O 0 0� y v)N mZZ c 0 O U ai 6 N M O O N Q Yeh and Associates 1AYeh and Associates, Inc. https://www.yeh-eng.com ,._-techni,,W• 6co14.1• Cmtstr, 6-Scr ,, Project title: Prado Road Interchange Location: PRADO RD, SAN LUIS OBISPO, CA CPT file: 25CPT-04 Input parameters and analysis data Analysis method: NCEER (1998) G.W.T. (in -situ): 15.00 ft Use fill: No Fines correction method: NCEER (1998) G.W.T. (earthq.): 15.00 ft Fill height: N/A Points to test: Based on Ic value Average results interval: 5 Fill weight: N/A Earthquake magnitude MW: 7.10 Ic cut-off value: 2.40 Trans. detect. applied: Yes Peak ground acceleration: 0.39 Unit weight calculation: Based on SBT Ko applied: Yes Cone resistance 6-------- 8 -- ---- --- 10 --- 12 -- ---- --- 14 - ---- --- 16 ------ 18 ..... ................. 20 ----- 22 .. ..... .... 26 28 30 ..... ----------------- 32 , a 36 -- ---- --- 38 -- ---- --- 40 ..... ................. 42 --- ..... .... 44 . .................... 46 ................... 48 --- - --- 50 --- --- 52 - --- 54 --- 56 58 ' 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 CRR plot 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 0 100 200 30C 0 2 4 6 8 10 1 2 3 4 0 qt (tsf) Rf (%) Ic (Robertson 1990) Mw=71/2, sigma'=1 atm base curve 0.8 0.7 0.6 u 0.5 0 0 0.4 Ln (V V) u 0.3 v U 0.2 0.1 0 1,000 QJ .N v 100 0 v c v a F v v to N E 0 Z HAi JD AUGER ag eartk. - Clay like behavior applied: Sands only Limit depth applied: No Limit depth: N/A MSF method: Method based 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 FS Plot HANDAUGER 0.2 0.4 O.E 0 0.5 1 1.5 2 CRR & CSR Factor of safety Summary of liquefaction potential 1 0.1 1 10 Normalized friction ratio (%) Zone At: Cyclic liquefaction likely depending on size and duration of cyclic loading Zone Az: Cyclic liquefaction and strength loss likely depending on loading and ground geometry Zone B: Liquefaction and post -earthquake strength loss unlikely, check cyclic softening 0 20 40 60 80 100 120 140 160 180 200 Zone C: Cyclic liquefaction and strength loss possible depending on soil plasticity, Qtn,cs brittleness/sensitivity, strain to peak undrained strength and ground geometry Liquefaction { .... .. �•�fiiS Wo Liquefadtion Project file: C:\Users\ king\Yeh and Associates, Inc\223-400 Prado Road IC - General\3.2 CPT\223-400 Prado Road IC Liquefaction CPT-01 to 04. q age 840 of 1-059 A-26 of 32 0 F- L1 U Lf1 N E ra a v m �, �n ......................... 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E I D �o8M=°S V C C C E O ISO W N Q O N V i0 CO O .Ni .- ID w O N 7 t0 w O N i0 W O N T 10 w O 10 O N N N N N M M M M M T � Y N � T m 7 N N O a C o a4ci E- rl Q% O C O N {SJ !� T O 6 �' V1 uiw t moo, u p L In Y N V O O N Y O c G E u Q E V ¢ > J ¢ O Ui U. ■ ■ ❑ ■ ■ Li Ln c � o o 'a vi N O Q ti v�N mZZ v t v R3 C a Y •m C U N f6 5 fd yV,� m E 41 O .w _ 21 v � ; V •C N 49— m 00 Go Ln Vv0 0 T ww78 CDw w N o m o UU m "M oLm m m 30 O _ C_ L O 12 4) N Ul t-n c O O m Rm fa :E:(/1 E "O ld C. E I D �o8M=°S V C C C E O ISO W N Q y O CL L m E E 3 m C m C O v m w 3 cr J 0 ��^ N QQ • O ______________a______._......._ _____ _�.......------- ...... 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L . . . . . l0 O O N 7 a0 O O N 7 a0 OD O N 7 l0 W O N V W W O N 7 %D W (M) 4jda(i 10 OD O V- .10+ 00 ON N N N N CD m M M M M V V V V V Ni v�i v�i M ()}) yjdaa V, O C V a N N 0 N n Z } } con Z U O � a v .Q .Q 0! a o. m m a t O ) 0 OJ r ,O L Cm d L O m.L a v �.N aY Va 3 c > IL6 O A 0 O H M 00 c 0 o a 0 0 y 7 rV mZZ Ln Y t Y0 C 5 N U m m 3 rn CD E o,o w- rn -C j iv V •C l L O N N @ ^ O i> > H Vv0 o � T w w 78 CD w N o m o UU m "M vi C Z Z m ri O 10 O C �o 3C:'M 0 L V O N W 9 ,�_• C� C V c O O D E V l0 o C u$ o m° S V C C C E O IUD W N Q O O U v 6 N M O N Cl) Q APPENDIX B - RELEVANT PREVIOUS DATA Page 847 of 1059 i N � I " -, �„y �o W � ^p• � ip i vlo uj z 1 2. _ __ __ -'Cr IE 0 h- J V y - \` -- — -- - --- -- — ---- o u- uy! fit 19 f I, V) o a _ _ Q a 2F-7 5 6 V T VG iii pp S J • s � 5�f a o, an ®® ED m ■® 4-1 IA A • B! Q pEit I � I Page 848 Qf;1059 • tVT[° tMF (X(�it1[INT ICJUN _ #_ .. � .. G - i . 33B'3M1WJ1VW - .. Nrn Z o W gN NOLLY MlNoo d w N6Z 50 0!"E J CL r /d O .. a 111JJJ t� /. ,OCT . I I ".... C 0 I co I ' 0 I 9 • i M _ \lll ?co co o¢ 07. CLcr oz FE o o 'O m O Z O \ g OD O i r N 9 !\ i ».as 2 !i �a ..;;: \moo¢ ' -\ •\ w November 1999 Project No. 99-42-0411 ['sR0 E Z E LOCATION: The drill hole location referencing local Z E � � Z y landmarks or coordinates General Notes 0 wm J -Ja. O u SURFACE EL: Using local, MSL, MLLW or other datum w rC4 y a � w n "' m W MATERIAL DESCRIPTION Sail Texture Symbol line in symbol column indicates 01 —Sloped Well graded GRAVEL (GM transitional boundary t2 2 1 25 Samplers and sampler dimensions (unless otherwise noted in report text) are as 60 Poorly graded GRAVEL (GP) follows: -14 4 2 (25) C Symba! for A 1 SPT Sampler, driven Well graded SAND (SW) R 34.9 mm ID, 50.8 mm OD -16 6 S 2 CA Liner Sampler, driven 3 (25) E 60.3 mm ID, 76.2 mm OD Poorly graded SAND (SP} G 3 CA Liner Sampler, disturbed 60.3 mm ID, 762 mm OD -18 8 I I I I R A 4 Thin -walled Tube, pushed 4 1111 (25) Silty SAND (SM) I 73.0 mm ID, 762 mm OD IIII N 5 Bulk Bag Sample (from cuttings) -20 10 D 6 Hand Auger Sample 4571 Clayey SAND (SC) 7 CME Core Sample -22 12 5 726 mm 8 Lexan Sample 9 Pitcher Sample Silty, Clayey SAND (SC-SM) 10 Vibracore Sample -24 14 6 11 No Sample Recovered Elastic SILT (MH) Sampler Driving Resistance -26 16 E Number of blows with 140 lb. hammer, falling 7 304n. to drive sampler 1-ft. after seating SILT {ML) I1 sampler &in.; for example, E Blows/R Description -28 18 / 25 25 blows drove sampler 305 mm 8 610 Silty CLAY (CL-ML) G after initial 152 mm of seating mm R 86/280 After driving sampler the initial -30 20 A 152 mm of seating, 36 blows I drove sampler through the Fat CLAY (CH) N second 152 mm interval, and 50 9 (25) E blows drove the sampler 128 mm -32 22 D into the third interval Lean CLAY (CL) 501152 50 blows drove sampler 152 mm after IM621152 mm 7621 of seating -34 24 10 762 Reff76 50 blows drove sampler 76 mm mm during initial 152 mm seating CONGLOMERATE interval ' Blow counts for California Liner Sampler -36 26 S08/ shown in ( ) 11 • 610 mm SANDSTONE Length of sample symbol approx-!mates recovery length -38 28 cation of Soils per ASTM D2487 or SILTSTONE D2488 40 30 GeoloR font at of O the top interpreted interrvanlbold MUDSTONE C K Strength Legend 42 32 Q a Unconfined Compression CLAYSTONE u ■ Unconsolidated Undrained Triaxial t = Torvane 34 p Pocket Penetrometer m Miniature Vane SHALE Water Level Symbols 46 36 7. Initial or perched water level J h T Final ground water level r GRANITE % Seepages encountered 48 38 r Rock Quality Designation (RQD) is the O� sum of recovered core pieces greater than �—o Paving and/or Base Materials 102 mm divided by the length of the cored . o interval. KEY TO TERMS & SYMBOLS USED ON LOGS ;"2253 M;°"" PPg a of 1059�8: B-3 of 97 November 1999 Project No. 99-42-0411 —FU11RU LOCATION: Proposed Lift Station E p E IL W o J p <P 2 Z UJ a to w ii Z w D acb3� p SURFACE EL 37 m +/- 0.2 (rel, assumed datum) MATERIAL DESCRIPTION �E w 4, 3= ZW E X Y �= �w 'R It a� 30 U C9 w ? <� aR8 p �R g -JJ ~ �Z o 2, z� LLw =1 Topsoil/Artificial Fill (An .......... ........... ........ ...... ..... .......... ......... .......... Lean CLAY with gravel (CL): hard, black, dry, with .......... •....... ................................................ 36 1 1 B (19) roots-•• ................. -•....................1Z_........... .- ....... ......... ........... .......... .......... .......... .......... .1..215. .......... .......... .......... .......... .......... ....... •--- -----:... 2 .: (27) - with shale gravel layer at 1.6 meters .••....... -1WV ............................. "74 9- "'Z4........... .............................. ...•••.•.• ••... •••• ---- -35 2 Alluvium (Oaf) ................................................. ...................... .......... ••....... ......•-... .... _-.... ...... .... Fat CLAY with gravel (CH): very stiff, black, moist .................... 34 3 3 (27) •••.....•• 19:1' ••.............................................-- 'ib:4 24. .......... ... 62... ... Win - .. Fat CLAY (CH): very stiff, dark brown, moist .. ..................................... .......... .......... ......... ........... ................ ......... •• -------.. 33 4 14.5 BGS = el. 107.5' .. ......................................................... .......... ...... _... ........ 4 >'• _ ' (8) ..................................................................... • 491A.. "'- "'" -%.7....3G """" ...............49......28 •. PA24 ZY.21. Sandy Lean CLAY (CL): soft to firm, dark brown, wet, with subrounded and subangular gravel to 32 s appropmately 3 mm diameter ......... .......... ......... .......... .......... .......... ....._. . . ..................................... . .••-••_......... ......... 31 6 NR 13 - with interlayered loose Clayey SILT (CL-ML) at 6 1 ....................................... ----.... ................................................. •.................• ......... ...................... ............................. ..... meters ------.-•I-_-n ..._..--....................................--- to 7 <>>(5)1 :t 3'J- lot ....................•. -•-_...5 W-21- pax ............._ tsa ........................................ 33 - ..- ........ I --•-••-- ............- - with light gray mottling and black organic pockets at ..-- ....................... .......... .......... --._.. .... _....._... s s 7.6 meters -- - ....... .......... ........ ...-•• .............................•-- ..............._........__. --•••-. . .......... B 9 7 ?s.;d (6) --....._...- •..............................-........... .................•_....... ••••...._........... ........ ....... ......... .... -.... --••........................ ........•. .......... ............. _..... - with interiayered SILT with sand (ML) at 9 to 10.5 meters................•- ....................................... ..._.......................-• ....•..... .......... .......... --•••---- r 10 --------- --------- 8 5 ..------•. --•-----• ............... .. . .... --••-•-• .. ......--• . 37" .... ••---.........•--•- .....--•• .......... ................ ... ---.•---• ....... 7Y-t•6 f 11.. .......... ........................... .......... ...................A ........ ....... .................... .... ..... --••......................... .......... ... .......... _........... I ................ ....... ........can CLAY (CL): stiff, olive brown, wet, with organic 12 9 (18) pockets ................. COMPLETION DEPTH: 12.3 in DEPTH TO WATER: 4.4 m BACKFILLED WITH: Cuttings DRILLING DATE: October 25, 1999 DH LOG (9"20411.GPJ/DK01) 1114M (9:22:5e AM) DRILLING METHOD: 203 mm diameter Hollow Stem Auger DRILLED BY: S/G Testing, Inc. LOGGED BY: CLLovato CHECKED BY: GSDenlinger TM lop and dam pi m ad we a W pmatioe dadaal eendtione mcouaemd at We time of trig at"treed lea"L sd"W ee m w*Jms my dWW at e1Mr ballone and Wkh tlr pu nge IOm. LOG OF DRILL HOLE NO. DH-1 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant Pag(FEATFY AG09 B-4 of 97 November 1999 Project No. 99-42-0411 - `V OZ E !_- W o S p Lum � Z J < fJ7 W -J < N W p aU yo m LOCATION: Station 2+90, Right 5 meters SURFACE EL: 39 m +/- 0.2 (rel. assumed datum) MATERIAL DESCRIPTION w Z 3" �= j 3 ^E Y O� z2 ,D T D �w �z ? w NN (L eR p iR °� J — �'�_ 0. Z Y zz • Artificial Fill (Af) ...................................................................... r • 76 mm Asphalt Concret Pavement (AC): r — . - .......... ....................• -•-•------ --------•- .......... 1 1 A 2 ::: `> :;: > (14) (15) ------- 19-3._ ---------- .AU....26 -•------- ................................ -------•-- ---------- ---------- .PP 86 406 mm Aggregate Base: Alluvium (Qal) Fat CLAY with gravel (CH): stiff, black, moist, with angular red chart to 25 mm .................... 18 9..._14 ti_ ...................................... ...27............ ......0 . .......... . ...40 -with shale clast at 1.5 meters .............:...... --------- .................... ...•----•• .......... ........... 37 2 3 (19) PP JA Fat CLAY with gravel (CH): stiff, dark brown and -•• .......................... .......... .......... ....... - - •--••-•-- mottled tight gray, moist 4 _ (12) - medium stiff at 2.7 meters .......... 19 2 - ......... ................._.. --15 3...25 ............. .......... .......... .......... ...........ee -• •---- 57 36 3 5 _.... 10 - with subrounded shale lasts to 6 mm at 3 meters ....... .......... ......... .......... .......... ... ...... ----- •--••••••• ....................................... -••------• --.••.............. .......... ............................. .......... ......... 35 4 •.................. -•.................. .................... ................................................... .......... .......... ..................................................................... ..................................................................... -34 5— ..................................................................... .......... ......... .. ........ ........... ..:....... ...... .... .......... . . ........ .......... ---•............................................. ................... ........................................ ........... 33 6 -_... ---••............................................ .......... ....-........................................... ............•----... •-------•• ........................... ------•.. ......... ....................................... .......... .......... ................... 32 7 .......... •................... •--...... .......... .......... ...... ... .............................. ............. ...... ..... .. .. .............................. ........ . .... . . . ................. .. ...... . .... .. 31 8 ..... •........ ................ ..................................... .. .......... .......... .......... ................... ...................... ............. .......... ..............._..........••- .......... ...... ._. 30 8 ......••.. ................... ............................. ......•. ................... .......... ....... •. ......... ..................... .............................. .......... .......... . ........ ........... 29 10 -•........ ---•................ .................... .•-...... ........... .............................. .......... .......... .......... --------- ........................_.... .......... ...................... .......... .......... .......... .......... .......... .......... ... .------ ••-•----•- 28 11 ......-.. .......... .......... .......... .......... .......... .......... ---•-•........... ....... .......... ......... .. .............................. ......... ......... 27 12 .................... ....................... ...... ........................... .............................. ... .......•-- ......... ....... COMPLETION DEPTH: 3.4 m DEPTH TO WATER: Not encountered BACKFILLED WITH: Cuttings DRILLING DATE: October 25, 1999 DRILLING METHOD: 203 mm diameter Hollow Stem Auger DRILLED BY: S/G Testing, Inc. LOGGED BY: CLLovato CHECKED BY: GSDenlinger Thi Mq and data pteta ted are a UMM6cation of actual eondtiom encountered at Ste tine of big at the &bed to - . Stbstafaee condllom my darer at other locstfom and with the pasppe of tine. LOG OF DRILL HOLE NO. DH-2 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant DH LOG (99420411.GPJ/DK02) t IRM (0:54:56 AM) Pag(PBUFY AG59 B-5 of 97 November 1999 Project No. 99-42-0411 GRD LOCATION: Station 5+00 E E p : a a W J 0: O g 2N d u a N to w a rn a Z J'O a3 O tnm SURFACE EL: 40 m +/- 0.2 (rel. assumed datum) MATERIAL DESCRIPTION �E w x 3� = �W E K �s zp =W CK UJZ ar"'- z 30 Cluj z w aW ag iR p ya a~ _I-J J eR Qw CL o Y z LLr, ZW Artificial Fill (Af)........... .......... .......... .......... .......... .......... Sandy Lean CLAY with gravel (CL): very stiff, brown, ....•............................................................... .......... 39 1 1 ::: (26)dry - moist below 0.6 meters ••................. ]9-5....1fi fi....JB..- .......... .......... .......... ................ PP 215 . •......• .......... .......... .......... ... ....... . .......... ..... ........... PP= 2 :::>`::: (13)fi...15......... - medium stiff at 1.2 meters -38 s 3 Alluvium (Qal) (37) Fat CLAY with gravel (CH): very stiff to hard, blait- ................................ . .............................. ...•-••. . ••••-- moist...................................................---•- 3 4 5 (21) - grades to dark brown with tight gray mottling below 2.4 meters 12..................................................... 9.7_ ...............................................................37 _.i5.5• ..25................................ ••••...... •--••.......-•-••••. --•••-••- Fe.1stif€ •............... .......... ................•••• .......... •-•--... 36 4 ... ......... ........... .......... ............................. .............. --•.......• -... ............................................................I- ........................................................... .35 5 .._....................................................... ..... .... ..... ..... ...... .. --•. ......................... ........... ..... ...... .......... .......... 34 8 --•-•----- ... -.... ---- -..._................._.........._................... --------- --------------- •---- ----- •---- -------- _ 33 7 -----•...... ..........-....._._...................... ---------- --------- _..••••- -------- ..... -...................................... ..... ................. 32 8 .......... • .......... ......••.. •--• .......... ................................................. ................................................ ........... .......... .......... .......... ....... . .......... ......- •---- .......... .......................... _..................................•• ......... 31 9 .......... _ .... .......... ...............•. ......... ....................................... .......... .......... .......... .......... .......... .......... ...... .......... -- --•. ..................... ....................................... 30 10 _..................... ..... .......... ......._ .......... .......... .................... .......... .......... .......... .......... ---------- .......... .......... --------- ... ....... .. ......... ............................. ......... 29 11 .................... •- .............................. ................. ......... ......... .............................. .............-..............• .......... .......... ........ ....... .. ....... ............. ................. ........• 28 12 .............................. ---------- --------- ......... .......... .............................. .............................. ......... ........... .......... ......... ......... .-•---•----------- - I ...... * ... ....... * COMPLETION DEPTH: 3.4 m DRILLING METHOD: 203 mm diameter Hollow Stem Auger DEPTH TO WATER: Not encountered DRILLED BY: S/G Testing, Inc. BACKFILLED WITH: Cuttings LOGGED BY: CLLovato DRILLING DATE: October 25, 1999 CHECKED BY: GSDenlinger TM 4 and daa pnaanlad an a tlmpYllcaOpn of actual eondliona aneaaaarad at the tew M arip at tha dtr.d taeaEca, SWwfa:. nn**" may drr at aiMr lotalions and Wh iM taawW dtlme LOG OF DRILL HOLE NO. DH-3 Laguna Lift Station San Luis Obispo Wastewater Treatment Plant PaoF�59 ON LOG (owzon t.tiPJrl%t 113) 11MAY (8:55:07 AM) B-6.of 97 November 1999 Project No. 9942-0411 �O W H uVIE m a M bI- 7t QQ � ( i3S)UUu nU 1N31b`=03 c o ci3t'» GNUS _ 3mwn-a y - in N �2ri n_ I �.� U ��viytx. OuaOui _ > .......... ............... ............... ._............. ............... 21--w LLM. 0 = a �p ...........................----_.......-- ............... ................ ... ...--------- ......_........ ............... ............... ....... ............... (� u E E W � �mY � o n �5 a N �tn U ti Uy Cy o n=° O U¢ aUN V¢~ as Wa, Y.I W _--------- _ --•-..... ..... ............... ....................._... •........... ....... .......... _... ...... _...................... ...._.... ................ V? ri N a a a 0 0 c c� z O 00. U~ Y � _ — ( •---Q--- -------------- --••-------- ---------•----- ---------------- ` ti ° C O U O U OON 2 CL— OD d M N z V M uJ m i fn W i g EE g ci LU U 2' ' I U n J J N O to to 20 A$ c _ J U IL d C7 81 J :aJ J mo YU Q' n^E L t t u� IM Ln } } } } } g L _ E U U U 00 M b y J J J U-C VI C to to (� lQ MlQ fQ L y O L r o .o wM J uJ E �Eo mo N� r)ih : ivifh :w iN>` i(oif� Er-;ao :mEv,�33�g Y Z m = fV : In : t0 : h : tG ; O o 3 t+ y E = O Q? a o.�°9a�L Y cc w MC U d �� 1 r-, _. r: r: _• _• j ems: N 11 O II 11 O! Oi Di Oi OE O( O _ �; _• p _: pi U U C J > > f iL b lA0 SUMAMRY(11(3tQB1t08:22 M) GRO I CL it C Q_ C H E J Ca W L in in 3 j O Q = .00 v � � J I U. � CD C a 2 u Cu I U J Cu C CD CO PLATteWtof 1059 November 1999 IaR0 rn Project No. 9942-0411`o 00 — -- -- -- ------ m C7 z w F �>� y F _ �� e o }- v 2 c t M'. R A p o H H H H H H H n m c O U D i an .6611 Mir (3S} 1N3lvAl 03 I, Z 11 Ito D n u n aovUv�xw QNVS N J � 3 nivA-8 �0.,$< E O OTC LO pt? v} .._......... -----• ui -------------•+ea _. ........... 0 U H(A } F- yt2<U uuuunuu ......... Cn Cr n O.......... ............... ............... .............................................................................. ............... ............... ................ a U � Y I z s£ o a c o� I W ixU) N _.._Q-_-_ -____---.-._-. _._.-___----- ________________ ----------- -_ __ ___•____________ _______________ _______________ x m ' L fL Vl OIL lY 1nU it nxnp �c 2 a U E 0 m UQF ILA F p V} U gc poi n'�` F r a y y� a € C z O aa' HF 0$ vl........` v c > C.LU F � ...._...•••............................. U Y u n tea}- u V Os'ni°�a1�E C i 'a 0 e e Z 8 0 1 s V ID a o c i a U) W M= _ N= _ _ = N= _ N= N= Co 6 LLY '- h o t 0 0$„ �a�a .I d U U w U v U U U t t V E� t > > > a� > d > m v > —y > ° u 2 820 Ua can aZ� �°° �°° �� �C, U)Sm =Y } S C C S pp Ell: C N 0 � tJ U � U 0) U a U � N v (D� U N .S c J LL LL lL lL IL lL c N c !!} [L Q a o 3 v J Ul G W; � �; (0 Ni N (o: Cos c Z Q.� _ F N N Li �r3 Z•t�_ E c 2 n� O W Z a. ram. me t O i p Q U ❑ �; _• Nj _: Ni _. _ _: _• j R J a ii / ❑; 1 ❑: ❑: ❑: ❑ 0: _: O: _: ❑: is ❑: _' O: U O U L 11 o 2 if J a fQ FL n E J Cu n 1. CD W LI Cu M 0 i y J i cQ Cn O U) 1 � 1 � iQ 0} Cu PUATge BSfbof 1059 November 1999 ORD Project No. 99-42-0411 C? _ z LU x CO �_ e �af!as- p 1N3JyAinD3 Qovc�v�tzw QNVS 31ni YyA-G �} .J h ippJ7 i. � C .tl r 0 �QCGO Q� .......... ... _ ....._......__. .................. < E io$�� E A ��o�tr_x<a .......... ............... ............................................... Cu onx G 4..L 0 ... 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O�� U a _...- .............._..... ................. ........... _............................._......_.. 0 a$ C O Q' -y oL of £pp£ `w i M z _ O U $ O O LU s ""na~" LL Cu a � C Q O 2r cc Z Q U v o y J U w i° B� $< a ee Cu C :3 _z Cu E a LL ID J V � = N= c 0 0 r C.- _ JCL > va Q 12 FEs �g z U C1 �Y LL U sn _ W Q; Q d ul fV 33 c� x O L :ICI: Ci z O Wz W i ��o7R�„ Up =i Si Sz U�CL iiln,a -LAB SLIF~RY(, i x"1I07:.I8 PM) 1059 P LfA+TrSUA November 1999 Project No. 99-42-0411 z 20 3 LEGEND (location) (depth,m) 0 DH-1 2.7 0 DH-1 4.3 . ..................................... ..... .................... ........... ...... ----------------- .................... . ............ z ........................... -------------------- ........................................... ..................... ............................... 7 ................................. ------------------------------ .................. CH or OH ........................................... ............. .................................. ................. ...................... 0 .... ...... ................ .............. ..... /CLor OL or OL LIQUID LIMIT (LL) CLASSIFICATION Fat CLAY with gravel (CH) Sandy Lean CLAY (CL) MH or OH ATTERSERG LMTS TEST RESULTS LIQUID PLASTIC PLASTICITY LIMIT(LL) UPAIT(PL) INDEX (PI) 62 28 34 49 21 28 PLASTICITY CHART Laguna Lift Station San Luis Obispo Wastewater Treatment Plant PLASM -MY CKART (N420411.GPJfD"1) 11rJ199(9:18:19 PM) • b November 1999 Project No. 99-42-0411 GRD 2 1 16 14 12 ai w• 10 y lot y 80 vV 40 20 0 00 80 ...........}........... ........ ...........:........... ......... ......... ...................t.............;........... ......... ......... : 0 f c ; . i E .....«.. ..................................... ......... ......... ......... ......... ........................ ... .......... �.............�............. .......................................... ........ «.... ..«..... ......... ...................... ........ ..... ............}........... ............. ........... n 9R AN _ __ "" •`"' �� Vtv I IOU zoo 220 240 260 280 300 NORMAL STRESS, kPa . EFFECTIVE COHESION, kPa EFFECTIVE ANGLE OF INTERNAL FRICTION, deg LOCATION DEPTH, m MOISTURE CONTENT, % UNIT DRY WEIGHT, kN/m3 MATERIAL DESCRIPTION SAMPLE CONDITION 30 13 DH-1 4.3 30 14.7 Sandy Lean CLAY (CL) Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station DIRECT SHEAR (99420411.GPJlawt) San Luis Obispo Wastewater Treatment Plant 11/3tfl2 (8:20:51 PM) Pdya48W Of- 3659 a r�1i GIRO November 1999 Project No. 99-42-0411 20C 18G 160 140 m Y 120 h W 100 N N 80 80 40 20 0 6 zu qu ou au 100 120 140 160 180 200 220 240 260 280 300 NORMAL STRESS, kPa EFFECTIVE COHESION, kPa 21 EFFECTIVE ANGLE OF INTERNAL FRICTION, deg 14 LOCATION DH-1 DEPTH, m 6.7 MOISTURE CONTENT, % 33 UNIT DRY WEIGHT, kN/m' 13.7 MATERIAL DESCRIPTION Sandy Lean CLAY (CL) SAMPLE CONDITION Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station DIRECT SHEAR (9W20111.GPJ/OiL01) San Luis Obispo Wastewater Treatment Plant .. I IrM9 (&20:53 PM) November 1999 Project No. 9942-0411 2114 C L 12 � to2 1060 toa so 60 40 200 ................................................................. . ................. ................................ .................. .......... . . ............. ..... 0 .................................... ............. ....................... ............. ........................................ ........ ......................... ------------- 0 0 ......... .............. ............. ............. . ............. . ............. ............. .............. ..... . ....... .............. .............. .......... .............. .............. ............. . ............. ............. ........... ........... . ............. . .......... .............. L ............. ........................................................... L .............. i .............. L .............. .............. ......... ............. ............ ............. . ............. . .......... .............. ............................. ................................ .............. ............... ............. ............. ............. . ............. ------------------ - ----------------------- ............. ............ ............ ............. .............. .............. ............. . .............. L ..... .............. .............. .......................... -------------- .... ......... - - ---------- ....... . .................... .............. .............. ----------- -------------- ............. . .............................. ...... ....... .............. L .............................................. .............. ............ ........... . . ............... .............. ... . .. ...... ------------- ............. . .............. L .............. L ........ MRD 120 140 160 180 200 220 240 260 280 300 NORMAL STRESS, kPa EFFECTIVE COHESION, kPa EFFECTIVE ANGLE OF INTERNAL FRICTION, deg LOCATION DEPTH, m MOISTURE CONTENT, % UNIT DRY WEIGHT, kN/M3 MATERIAL DESCRIPTION SAMPLE CONDITION 30 14 DH-2 2.4 11 15.3 Fat CLAY with gravel (CH) Driven Ring DIRECT SHEAR TEST RESULTS Laguna Lift Station DIRECT SHEAR (9W2041 I.GPJ/DK02) San Luis Obispo Wastewater Treatment Plant 1 Iriffig (B:20:50 PIA) ............. November 1999 ORD Project No. 99-42-0411. .............. .............. ....... ...... ... . ...... ...... ..................... j . . ...... ........... ... .......--.........-.-... . . .... ... ........ ....S :Test Mefhod: AStM d1557 .. ......................... ...... ............. ... :.. .... .- .. ......... 21 .. ...... .-......-.... .......- ..... . ......... .. .................. .... .R . .. .. *........ ........ .... ... ....... . . ........ .. ................. .......... . .........-..-.-.. .. ..-.. ... ... . .. ............................. . ...........................I . .. .. ............................ . . .... ...... . ... . ...... . ....... .. ...... ....... ....... ...... .- .. ..... ...... .. . ........J................... . .......... .. .................................. ..............C...................... 20...... .... .............................................. .... ........ ...... ....... ..... .. .--.. .K ..Z...............E........... ......- .-.. ...... ......-. ...... .... .... ......2..........f....,.. ....... ...... .. ..... ........ .... . .... .. ......... . -. ........... .. ............................ ....... ..... - ........... ..............................a... ...............V .. -........-...... ......................... . ..... . 19 ...................................................... .I. .-...-..-..-..-..- .. .. .-.....-.....-. .. ........ .r ... .. . . ........: .....S. .........V.......................E................ . ....... ........ ......................... ...... .. .. I. . . .'t.... ..D. ...: . . ...... - - - ...... ........... ...... ... .. ... .... .......-... .. .... ..................... ....... .... .... ...\ .... ......... ...... ... -- - ... ... .....-.-....... ..- ..-- .-......-.-. ... ... . ..... ..... ........... .. ...... .... .................... ....................L......z............................. ................... ...... ...... ......... ... .. .. .... ............... .............:.............. ....................r........................................................ -------.. ............................................... ............................. . ... ................ ...... ................. ------------- ...... ....... ... ............... .. ...... 17 ....................----------------------------------------------------------------...... . ... ... ........ ...... ........................ ........................... . .. ------- ...... ..... ........ L ............... ............. .................. . ...... .... . ..... ......................... .............. ....................................................... ....... . ...... ...... ...... ....... ...... ...... ........ ..... . ....................... . ............ ............ ...... ....... ....... .............. .......... .............. ...... ....... .. .................... ... .. ..................... . .............. . . . ...... ...... . .............. . .. ...... . ...... .............. ...... ...... ........................ .............. ...... ...... ........... . . . . ------ ------- ............... ...... ...... ...... ...... ....... ............ ...... ...... . ..... 7 ------ ------- ...... .............................. ------ ............... ...... ........ . ..................... ...... .... ....... ....... .............. ...... ........ ...... ...................... ...... .... .............. ...... ....................... ............... ...... ...... .............. ........ ...... ....... lu 15 20 25 MOISTURE CONTENT, % LEGEND CLASSIFICATION MAXIMUM UNIT OPTIMUM WATER (location) (depth,m) DRY WEIGHT. kN/M3 CONTENT. % 0 DH-1 0.6 Lean CLAY with gravel (CL) 17.2 15 COMPACTION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant T Tvuoa(estasAM) n' COMPA"ON(MEMIC) (M2W11.GPJ1D"1) PLAdIA T of 1059 November 1999 Project No. 99-42-0411 z 0 ................... . .......... ....... . ....... .. . ....... .. . . . ............................................... ... ...... ..... . ..... ............. ........... ....... . ............... 2 .................... .......... ........ ..... .... . ........ ........................ I ........... . ........... . ........................... ........... ....... 7 ............................. 3 .................... ........... t ....... ........... J J ... ................... 4. .......... ........ ........ . ... ... . -------------------- ........... ....... 4 .................... :L ...... --i- ........ ........ .......................................... ...... I . ............ ........... ........ ............. ................... ........... .......... . .......... . . . .............. . ........................ ...... .................. .. ...... ....... .......... ....... ..... ........ .......... 6 ................... . .......... . .................... * ................... :7 .............. . ......... ......................... . ........... ........ ............ .............. 7 .................... ........... ....... ...... ........ ------ ....... ....... . ..... 8 .................... .......... ...... ............... .. ................... ..................... ...... ........ .......................... ........ .. 9 ------------------- --------- ......... ........... ............ --------- ........................ ........... . ..... . ..... I . ............. 0 .................... ................... ----------- ........... ........ ...... :� ----- .................. ----------- .... ......... ............... ........... ....... 2 10 100 1000 VERTICAL EFFECTIVE PRESSURE, kPa LOCATION DH-2 DEPTH, m 1.2 INITIAL MOISTURE CONTENT, % 27 UNIT DRY WEIGHT, kN/M3 15 MATERIAL DESCRIPTION Fat CLAY with gravel (CH) SAMPLE CONDITION Driven Ring CONSOLIDATION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant &ppMMLIDAMN (9W2UI I.GPJIDK02) PL�Je �Eof 1059 11r1W(9:17:1QPM) ------- - B-1 5 of-�97 November 1999 URD Project No. 99-42-0411 7 01 ................... .......... ....... ..........• - - - --------------- ...... .... . ..... ........ . . .......................... ........... -------- - -- ......... 2 ................... ........... 1 ....... ..... .... . . ................... . .......... ....... ..... . : ....................... ; ............ .... . ..... ..... .............. ................... ........... ------ ------ ................. ------- . .......... ..................... 3 i ....... ...... r: ---- i ---- i ....... ..... ............... 7 4 -------------------- ---------- ..... . .......... ................... ...... ............... ........ ...... .................. ........ ............ ..... ------------------- - ---------- - - - < --------------.......... ....... .......... - - ------------ ...... . ....... - - - ---------------- ........... ............ i, ---------- ...... 7 .............. 4: ...... i 4 ........ . ......... ......................... �--4-4 ................... ....... ....... ................. ........... ......... ........... :.-! ................................ .............. ......... ............................... ....... ...... 9 -------------------- ........... r.. .................... ......... .... ... . .... . ..................... . ...... . ..... . ... . ... . .. . ..... 10 ------------------- - ---------- ........ ------------------- ......................... . .................... ----------- ................ 77 ............... ........... ............................... ........ ..... . .... ................... ........... ........ 121 1 10 100 1000 VERTICAL EFFECTIVE PRESSURE, kPa LOCATION DH-2 DEPTH, m 2.4 INITIAL MOISTURE CONTENT, % UNIT DRY WEIGHT, kN/M3 25 15 MATERIAL DESCRIPTION Fat CLAY with gravel (CH) SAMPLE CONDITION Driven Ring CONSOLIDATION TEST RESULTS Laguna Lift Station San Luis Obispo Wastewater Treatment Plant CONSOUGAMN (9W2041 I GPJIDW02) WNW 16:17.24 PM) . .......... PLATkj9-§§3 of 1059 ealth pence ssociate'5 Report Number : 100338 Purchase Order Job No. 99-42-0411 Sample Description : 1- Bulk Soil Project . LABORATORY REPORT CHRIS LAVATO FUGRO WEST INC. 1012 PACIFIC ST. SUITE A SAN LUIS OBISPO, CA 94301 California Test Methods : 532,643 Auto Submitter Resistivity pH No. Sample Number ohms/cm Units _204524 DH-1-2 @ 6' 3,449 7.28 Chloride Sulfate PPE PPE Date Received : 29-OCT-99 Date Completed 05-NOV-99 Date Sent : 05-NOV-99 Page f i of 1 'Milliliters Water Added 50 100 150 200 250 300 350 400 ----------------------- Resistivity Obi -cm --------- ------- ---- ------------- Sample No. DH-1-2 @ 6' 3630 3812 3630 3521 3630 3449 3812 3739 �t _,Remarks : Sample(s) and sampling data as provided : Analyst(s) : ED Ref by : C. Wockner California ELAP No.: 1406 Reviewed b�dS � - rAIHA Accreditation No.: 172 Thomas Shultz NVLAP Accreditation No.: 101384 AIHA ELLAP Accreditation No.: 10985 Technical Approval: LACSD Lab No.: 10125 Laboratory Dir tor, Jamie Steedman-Lyde 10771 Noel St., Los Alamitos, CA 90720 714/220-3922 FAX 714/220-2081 e-mail hsa@eaftWink.net Attachment This report pertains only to the samples investigated and does not necessarily apply to other apparently identical or similar materials. Thai a 19(4 0559 for the exclusive use of the client to whom it is addreswd. Any reproduction of this report or use of this Laboratory's name for advertising or ppyybLL' ' y purposes without written authorization is prohibited. t'li' Of 97 m N W H Z m a l/ g { a u o Zpm oav J�o i Z � J o- c / m U) N C U 0. to S. O O Go pC L J m a E c2 Page 865 of 1059 O co m I I , 1 I ' N N L r�g E C�jC o I m 7 U o b Z ma 1 m N w z `° a a O�U _a a) U :3 .S O�� � O CD "— Z>16J O 7 C c0 [a CO m U C C C7 N m m� �• VA � m r c � a am a U u < y� c u Q _ Page 866 of 1059 Standard Penetration Test (SPT) split spoon sampler having a 2-inch (50 mm) O.D., 1 3/8-inch (35 mm) sI.D. and without liners. Sampler is driven in three 6-inch (305 mm) increments by dropping a 140-lb (63 kg) weight 30 inches (760 mm). The reported blow count is the sum of the blows for the last two increments. CAM California split spoon sampler having a 3-inch (76 mm) O.D., 2 3/8-inch (60 mm) I.D. with liners. CAL Sampler is driven in three 6-inch (305 mm) increments by dropping a 140-lb (63 kg) weight 30 inches (760 mm). Thick-walled modified California split spoon sampler driven 12 inches (305 mm) using the rig's kelley Is I Thin -walled Shelby Tube sampler that is pushed into the ground using the rig's hydraulics. FSand Cone Sampler MM JHANq Hand driven modified California sampler with liners. LIW XBulk sample obtained from drill auger flights, backhoe cuttings or hand excavation. NR No recovery Consistency of Cohesive Soil: Cal N-Value SPT N-Value Undrained Shear Strength (Su) psf k a Consistency 0-2 0-1 < 250 < 12 very soft 3-6 2-4 250-500 13-25 soft 7-12 5-8 500 - 1,000 26 - 50 firm 13 - 22 9 - 15 1.000 - 2.000 51 - 100 stiff 23 - 45 16 - 30 2,000 - 4,000 101 - 200 very stiff > 45 > 30 > 4,000 > 200 hard Relative Densitv of Granular Soil: Cal N-Value SPT N-Value Consistency 0-6 0-4 very loose 7 -15 5 - 10 loose 16 - 45 11 -30 medium dense 46 - 75 31 -50 dense > 75 > 50 very dense S,,,� PP n Undrained strength (t = torvane, uu=uu triaxial, pp = pocket penetrometer, h = hand vane) Initial depth to groundwater Groundwater level after drilling Notes: Soil classification and descriptions are performed in general accordance with ASTM D-2487 and ASTM D-2488 based on the Unified Soil Classification System. The logs represent the interpretation of field classifications and testing, interpolation between sample intervals, results of laboratory tests, and the conditions observed at the time of exploration. The transitions between soil types and strata are approximate and can be gradual. Soil and rock materials vary in type and other geotechnical properties between points of observation and exploration. Groundwater and soil moisture conditions vary seasonally and for other reasons. Explorations and services have not been requested nor performed to assess the presence of absence of hazardous or toxic materials. San Luis Obispo Water Reuse Project San Luis Obispo, California LEGEND FOR TRENCH LOGS Project No. 01-52-0721 _ Figure A-1 Page 867 of 1059 B-20 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 12, 2002 Driller: S/G Testing Completion Depth: 3.4m (11.0') Ground Elevation: 36.5m (119.7) Groundwater: Initial depth: After drilling: Logged by: G. Fiegel Comments: Groundwater was not encountered Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cuttings Depth m a' a c ^ o a) '� c M E -• c cY ^ �v ` m E ° 3 3 a E `-' a DESCRIPTION AND CLASSIFICATION a = c `� Other O Y O O OL O Tests OCOU Af Artificial Fill: - sPT 4 1 3" (75 mm) Asphalt Concrete over 15" (375 mm) 29 Qal Base Material sand and ravel Alluvium: 1 Fat CLAY (CH): soft, dark green, moist, orange 5 CAL 12 2 staining, with trace amounts of gravel (18 6) 32 - medium stiff, dark gray, brown and gray mottles, 2 sPT 7 3 blocky structure 29.4 - orange staining 3 1 j ` 18 4 -stiff 119 (18.8) 30.2 Pp=2.5 ksf Total Depth = 11.0 feet (3.4 meters) 4 - 1 5 6 2 7 2 8 9 3 San Luis Obispo Water Reuse Project BORING NO. B-305 San Luis Obispo, Califomia SLO WWTP Property Project No. 01-52-0721 Figure A-16 Sta. 0+860, CL of Pipe Page 868 of 1059 B-21 of 97 Drilling Method: 6 in (150 mm) Hand Auger Date: March 19. 2002 Driller: Fugro Completion Depth: 4.9m (16.0') Ground Elevation: 36.6m (120.0') Groundwater: Initial depth: 4.6m (15.0') After drilling: 4.4m (14.5') Logged by: G. Fiegel Comments: Hammer Type: 5 lb Hand Hammer Backfill Material: Cuttings Depth N a� .. " c E .. _0 ° _ C �� _ cn cn 0 3 E o DESCRIPTION AND CLASSIFICATION a N a Other Tests �, `` Y 2! 0 2 m� U) o o ��M0 o � Qal Alluvium: Fat CLAY (CH): stiff, dark brown, moist, occasional roots, orange staining 1 HAND 40 1 - dark gray I 5 - black, occasional gravels and sands, subrounded, H ND 80+ 2 gray silt partings 2 - gray, orange staining, manganese specs 3 1 I - yellow brown, orange staining, manganese specs HAND 32 3 - medium stiff, occasional gravel 4 - black, occasional sand and gravel particles, orange stains 1 - soft, brown, increasing gravel and sand 5 HND A 1 d - medium brown, wet, with sand No Recovery ` Total Depth = 16.0 feet (4.9 meters) I 6 2 7 2 N r g o c� I 0 w V7 U 9 3 San Reuse ®mom BORING NO. B-306 SanuisOispo Luis Ob spoeWatfCal fo n aroject m SLO WWTP Property Project No. 01-52-0721 oReclaimed Water Tank Figure A-17 J rage 669 of 1059 B-22 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 5, 2002 Driller: SIG Testing Completion Depth: 4.1m (13.5') Ground Elevation: 40.5m (132.8') Groundwater: Initial depth: After drilling: Logged by: G. Fiegel Comments: Groundwater was not encountered Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cuttings Depth C. a j o a) c D c c Y a a� v u, M w 3 m o DESCRIPTION AND CLASSIFICATION m aC Other N N: Y 75 3 o U) O 0L O Tests CD Af Artificial Fill: 10" (250 mm) Asphalt Concrete over 8" (200 mm) SPT 8 1 Base Material sand and ravel 19.3 Lean CLAY CL : medium stiff, dark brown moist 1 j K A Oal Alluvium: Compaction 5 c1 17 2 Fat CLAY (CH): stiff, dark brown, most, some 119 18.5 orange staining (18.6) sPT 2 8 3 - dark gray 3 1 4 CAL 19 4 - stiff, occasional decaying roots (122 ) 22.6 Total Depth = 13.5 feet (4.1 meters) 1 5 6 2 7 2 8 9 3 San Luis Obispo Water Reuse Project ©� BORING NO. B-401 San Luis Obispo, California Prado Road, Sta. 0+525 Project No. 01-52-0721 CL of Pipe Figure A-18 Page 870 of 1059 B-23 of 97 Drilling Method: 8-V4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: SIG Testing Completion Depth:15.3m (50.3') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.5m (245) After drilling: 7.5m (24.5') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth a� a a o c _ _ cY �8 Cn E E in o� 3 3 a E o DESCRIPTION AND CLASSIFICATION a Ln a Other Y o 0 07 0 o Y a Tests �CO 'm Af Artificial Fill: 7" (175 mm) Asphalt Concrete over 4" (100 mm) Co=1, VOC=0.8, sPT 13 1 Base Material (sand and ravel 12.6 H,S=O, 1 Fat CLAY (CH): stiff, light to dark brown, moist, with _J LEL=O, PP>4.5 ksf few pieces of subrounded gravel to 3/4" (75 mm) diameter Grain Size 5 CA CA ]L 17 17 2 22 - with pieces of plastic 114 15 1 VOCo=0 5, (18.0) LEL=O, pp>4.5 ksf Qal Alluvium: Lean CLAY (CL): stiff, dark brown, moist 3--JC C0=1, VOC=0.5, sar 10 3 H,S=O, LEL=O, pp>4.5 ksf 4 Atterberg - 1 - with medium grained sand layer Limits, UU cA� 17 4 (18 6) 1119 8.2 C0=0, vo S- �2, 5 z- LEL=O, pp>4.5 ksf 6 2 C0=0, VOC=0.5, sar 15 5 - with 3" (75 mm) thick sand layers H,s=O, LEL=O, pp=1.0 ksf 7 Well graded GRAVEL with clay and sand (GW-GC): _ medium dense, light brown, moist 2 8 CAL 32 6 123 (19.3 ) 22 9 X co=o, Lean CLAY with sand (CL): stiff, orange brown, wet VOC=0.5, sPT 12 7 H,S=O. LEL=O, San Luis Obispo Water Reuse Project ®� BORING NO. B-402 San Luis Obispo, California Prado Road Project No. 01-52-0721 Sta. 0+760, CL of Pipe Figure A-19 rage u t i or i uoy B-24 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.3m (50.3') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.5m (24.5') After drilling: 7.5m (24.5') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth _� a d �_ C O a)GY Irl _ E -- �o U O 3 3 DESCRIPTION AND CLASSIFICATION a `� a O O cn O Y O O U) _o O �v O L O Tests m m C7 � m 0 Lean CLAY with sand (CL): stiff, orange brown, wet Pp s (Continued) 1 3 CAL 41 8 138) (21.6 19.4 Poorly graded SAND with clay and gravel (SP-SC): medium dense, orange brown, wet 2 q CO=1, SPT : 20 9 VOC=0.8, H2S=0, LEL=O 3 Fat CLAY (CH): very stiff, moderate light gray brown, moist, with pieces of gravel to 3/4" (75 mm) diameter 4128 4 CAL 35 10 (20.2) 22.7 pp'4.5 ksf KJfm Franciscan Formation: 5 CLAYSTONE - "Fat CLAY (CH)": moderately hard V000.5, 5 sP , rock moderate) weathered, light gray brown H2s=o, Total Depth = 50.3 feet (15.3 meters) LEL=O 16 5 7 8 6 9 San Luis Obispo Water Reuse Project ©� BORING NO. B-402 San Luis Obispo, California Prado Road Project No. 01-52-0721 Figure A-19 Sta. 0+760, CL of Pipe Page 872 of 1059 B-25 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.7m (51.5') Ground Elevation: 41.5m (136.V) Groundwater: Initial depth: 7.6m (25.0') After drilling: 7.6m (25.0') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth `. CL n E co =3 O ? .�c cY �o CA in 3 3 E o DESCRIPTION AND CLASSIFICATION n. N Other � ) H �U Tests CO co-0 rn Af Artificial Fill: 9" 225 mm Asphalt Concrete CO-2 I VOC=5.0, Lean CLAY with sand (CL): stiff, dark brown, moist, SPT 9 1 9.9 112s=o, 1 with pieces of brick, concrete, and asphalt up to 3" (75 LEL=O, pp=" ksf mm) diameter I 5 7 21 2 118 (18 6) 13.3 Direct Sheai 2 I 3 1 I SPT : 2 3 - piece of gravel stuck in sampler shoe I Qal Alluvium: 4 Fat CLAY (CH): very stiff, light brown, moist, with BUIK A trace amounts of subrounded to rounded sand and -Jr gravel uu, Co=�, CAL 28 4 131 19.3 VOC=0.2, 5 (20.6) LEL=O, - pp>4.5 ksf I 6 2 Co=1, I SPT : 8 5 - orange brown, with few black specs VOC=0.5, 112S=01 LEL=O, pp=2.0 ksf 7 Sandy lean CLAY (CL): stiff, light brown, moist 2E i I $ 8-- CAL 11 6 Z - wet (� 9 5) 28.1 Atterberg Limits, UU pp=2.0 ksf o c� I o - - Fat CLAY with sand (CH): stiff, light brown, wet w N LL " 9- 3 CO=2, I VOC=0.5, 12 7 H,S=o, LEL=O. 0 San atf Reuse uis �bis BORING NO. B-403 Obispoeispo San Cal fom aroject m w Prado Road Project No. 01-52-0721 o Sta. 0+820, CL of Pipe Figure A-20 rage i3 t J oT I UbU B-26 of 97 Drilling Method: 8-1/4 in (210mm) Hollow -Stem Auger Date: February 8, 2002 Driller: S/G Testing Completion Depth:15.7m (51.5') Ground Elevation: 41.5m (136.1') Groundwater: Initial depth: 7.6m (25.0') After drilling: 7.6m (25.0') Logged by: N. Derbidge Comments: Hammer Type: 140 lb Autotrip CME with 30-in drop Backfill Material: Cement bentonite grout Depth E o a a E jo w EY a�a `. � in 3 3 o DESCRIPTION AND CLASSIFICATION a —D a)Other Tests u- Y o o m n cEo o o- ~ rn o c O m Cg � U 0 Fat CLAY with sand (CH): stiff, light brown, wet pp=2.0 kSi (Continued) 3 CAL 12 8 - without sand 120 31.1 uu, pp=1.0 1 (18 9) ksf 2 4 Co=O, v sPT 8 9 - medium stiff H2S, =O,S= LEL=O, pp=1.0 ksf 3 4 4 cu 14 10 -stiff 131 (20 5) 20.5 PP=2.0 ksf -5C Co=1, voC=0.5, sPr 35 11 - very stiff, with frequent charcoal inclusions H2S=O. LEL=O, Total Depth = 51.5 feet (15.7 meters) 6 pP>4.5 ksf 5 7 8 6 9 San Luis Obispo Water Reuse Project �© _ BORING NO. B-403 San Luis Obispo, California Prado Road Project No. 01-52-0721 Sta. 0+820, CL of Pipe Figure A-20 Page 874 of 1059 B-27 of 97 Brown and Caldwell Project No. 01-52-0721 70 60 0 50 k 40 c 30 a 20 10 Atterberg Limits V��e . .e 01 2 106-2 f,,• CH or a 304-3; 704-2 O 0 2-2 303- 5 MH or OH ICL oe-20120103-4 03 402-4 602-2 8X or OL CL 10 20 30 40 50 60 70 80 90 100 Liquid Limit - Sample Depth (ft) Description and Classification Liquid Limit Plastic Limit Plasticity Index 101-2 4.5 Fat CLAY (CH) 70 21 49 104-2 4.5 Lean CLAY (CL) 49 22 27 106-2 4.0 Fat CLAY (CH) 74 25 49 201-3 6.5 Lean CLAY (CL) 42 21 21 203-4 14.5 Lean CLAY (CL) 37 19 18 204-3 9.0 Lean CLAY with sand (CL) 42 20 22 303-5 19.0 Fat CLAY (CH) 56 25 31 304-3 9.0 Fat CLAY (CH) 70 27 43 4024 15.0 Lean CLAY (CL) 39 20 19 403-6 25.0 Sandy Lean CLAY (CL) 32 18 14 502-2 4.0 Sandy Lean CLAY (CL) 31 18 13 702-2 4.0 Lean CLAY (CL) 44 20 24 704-2 1 4.0 1 Fat CLAY with sand (CH) 54 19 35 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D4318 ATTERBERG LIMITS TEST RESULTS Water Reuse Project San Luis Obispo, California P L ,a5e`i -A of 1059 13-28 O 97-_. Brown and Caldwell Project No. 01-52-0721 100 r*J to 60 o, c C 40 c as as a 20 Mechanical Sieve Analysis Results 10 1 Grain Size - mm roxi roxilil GRAVEL SAND SILT or CLAY coarse Tine coarse medium fine Symbol Sample Depth Description and Classification C, C (ft) 402-6 25.0 Well Graded GRAVEL with 2.8 124 Clay and Sand (GW-GC) Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D422 MECHANICAL SIEVE ANALYSIS RESULTS Water Reuse Project San Luis Obispo, California PLATE B-2d Page 876 of 1059 B-29 of 97 Brown and Caldwell Project No. 01-52-0721 M Compaction Test Results 116 114 fffl-1 `C+Il 10 12 14 16 18 20 Water Content - % Symbol Sample Depth Description and Maximum Dry Optimum Water (ft) Classification Unit Weight Content ( co (%) ♦ 401A 3 to 6 Fat CLAY (CH) 113.5 15.0 Projcct: City, of San Luis Obispo Water Reuse Project Test Method: ASTM D 1557 COMPACTION TEST RESULTS Water Reuse Project San Luis Obispo, California P ATAE &-73(9f 1059 B-3Q O- 97 Brown and Caldwell Project No. 01-52-0721 10, Or 2 8 10 12 Consolidation Test Results Consolidation Stress - psf 10, 10, 10, Total Unit Water Symbol Sample Depth Description and Weight Content (ft) Classification (pcf) • 404-2 4.5 Fat CLAY (CH) 127.4 23.6 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D2435 CONSOLIDATION TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-4d Page 878 of 1059 B-31 of 97 Brown and Caldwell Project No. 01-52-0721 Direct Shear Test Results E"I 3 1 01 1 1 I 0 1 2 3 4 5 Normal Stress - ksf Symbols Sample Depth Description and Friction Angle, Cohesion, (ft) Classification (degrees) c (ksf) ♦ 403-2 5.0 Lean CLAY with sand 37 0.1 (CL) Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D3080 DIRECT SHEAR TEST RESULTS Water Reuse Project San Luis Obispo, California P L Pag e6�9 of 1059 B-32 of 97 Brown and Caldwell Project No. 01-52-0721 L02 5 4 1 0 UU Test Results 4 8 Axial Strain - 12 Sample 203- Sample 204-6 Sample 203-4 16 Sample Depth Description and Cell or Undrained (ft) Classification Confining Shear Stress Strength (ksf) (ksf) 203-4 14.5 Lean CLAY (CL) 1.9 0.8 203-6 24 Lean CLAY (CL) 2.4 2.0 204-6 24 Fat CLAY (CH) 2.4 1.2 Project: City of San Luis Obispo Water Reuse Project Test Method: ASTM D2850 UU TRIAXIAL TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-6a Page 880 of 1059 B-33 of 97 Brown and Caldwell Project No. 01-52-0721 3.0 Sample 2.5 0.5 pc' UU Test Results 4 8 Axial Strain - 12 16 Sample Depth Description and Cell or Confining Undrained Shear (ft) Classification Stress Strength (ksf) (ksf) 402-4 15 Lean CLAY (CL) 1.9 3.7 403-4 15 Fat CLAY (CH) 1.9 5.1 403-6 25 Sandy Lean CLAY 3.0 0.8 (CL) 403-8 35 Fat CLAY (CH) 3.6 0.9 Project: City of San Luis Obispo Water Reuse Project Test Method ASTM D2850 UU TRIAXIAL TEST RESULTS Water Reuse Project San Luis Obispo, California PLATE B-6c Page 881 of 1059 B-34 of 97 +. Y i � .w. of Y ••••••• :�fI��JNIBl9�0"-0P79d1 -�TY1 (SJOlaw) NOIJVA313 U., ry ry N I I " < g = N N $ ag2a9a§�? 91 s �c Cc°b u& u�a Yas. dash I I I I$xE L ar' raT �a all is a3 n ail $ E on �I 8 IL 0 a >_ Gall^d 8 advN) do,p ww Z91 o up- wwu,ou 6m Sf9 v Rlq—,tv ,awwDH wwgZ . 00 :ww" . 01 .,>Idu,os oryml!IDJ Pa1ppDI1 wu,OS - To •."f - '(Ir aj O O I (s)alaw) NOILVA313 b an....'.'i,i�r'Q wro_ Oliana.'ut•a* "•i' wir �' LII,Yw^ I�w.� mn�f �' .wm • I��,OJ7yw�,�i n 0 M1w • w,n' W.w waiN ��YY �.3 nw.d ':B® b•a0 uve _DwI ..Y•t r..y Y,n s�nn +n. onYY wgla,(] .tiw n,e —wn lwf imn�x.R b,r,. gprta 31 „IAYo m n - L'WWf19-ASTY( (57SNS7+b31afA{A7'D-lND7 wSh ■; w1,1 ,H D +Fh f11t Pat —9R1. , t.,, A^�wYd Ye15 A 9 �we*+r m m w m m = = m m = = m m m 059 (0) W S C 5.0 Results and Findings Figure 5-3 Cross Section Transect Lines Map B-6 B.7 B 10 B-8 B-9 B-14 8-11R B-13 B� B B-T5 B-16 B-12 B-17 C ,_.,B-19 B-20 B-21 San Luis Ranch Well No. 2� B-25 B-18R B-22 B-23 B-24 8-29 C' B-32 B-31 0 8-33 B-34 A' Remedial Investigation Report City of San Luis Obispo Legend Cross Section Transect Maximum Tetrachloroethylene (PCE) Concentration MCL > 5.0 ug/L a Non -Detect :5 2.5 pg/L 2.5-5.0pg/L 5.0 - 10.0 pg/L 10.0 - 20.0 pg/L >_ 20.0 pg/L Note: MCL - Maximum Contaminant Level ug/L - microgram per liter 5-12 Page 883 of 1059 B-36 of 97 a a C O N N O V IT Ln d T LL reoi�I oa S Z �1 � � � 2 F S 2 Ti H 'J wR y 1 uW AGG r` rn 0 r` M c � m O CL 1r 0 c 0- 0 y) 0) O (1) 0 > J C C ca ui -0 N O E> Q� U Page 884 of 1059 U) D7 C C LL w m c ca O 1, JIIV— 1MIN I. ' { Uzzz { 1. f { r S 1� { 1 I eo. 4t�8 — o r:9 O �YWJOQ�7;1 {1111 U1'G ^ m ARMOM lot Sfi — m r� C CD tA U " V { W co� W _� Ilswo ul ua{ena{3 J LL oB 375 d' a 1� W 6 N Cr n byy c' KK q G i7 Oa O i OEM W }} G N G C7 IM®© m �Q§ aZ EINEIM l M y� e � W V _7 z oao L 0 Q ^ N/W� I..L C O o a (CS � O)o � .� ti a) 0 E ti rn 4- 0 OD m Page 885 of 1059 � D E � LL 'a m / :3 Cl) cr � 0 U) 3 � B z � 0 ■ . _,mom u Q § ■ G § � f � � � ! ! a ■ . B 2 OWN r__ LL. ¥ 3 0 c ¢ ® m � § ) \ ;|| ! !§ ) � G 2 �\ } 2 \ ��■ ) aBiG ( �B1S a co $d■k L- 0 _ ; CL IQ a)_ � Jf3 DEE �0 CL m 'L� ) { imO ! \: � uj ]/E km ® � � @ 0 E $ � IxU Page 886 0 1059 w Lip � N N J } 1 0 O N co 0 (9 ca Q v M � V o u° J M � W M U. L Q L 76 O H Q u O a V) u ou m -' J Z O J V) i ►�1 06 J a Z cw t a W m V) O O J Q u Z O V) J U. O O W �1-4 Q u > H W _ H V) J u O T io i0 10 IU N N n = Z Z j� d.oZ L b m N Ny 12i N O '> z$ Vl C"S fS CS LS C.J CS u fn VI (n ZS in tJJ > > + �J a1 s v 0 ! co cl V) N V) O O V� O vl O N O .f'1 O J1 O O ul O N O M d d l/1 1!1 10 10 n n 00 O 0 Z H a O 6 c O M u L U. c O v w v v v y (:U) 44dad 0 0 GO O M VI Ln O ID �a O in O It d Ln n n 00 (a)) 41da4 Y. O u1 O O (11) 4adad N 0 w d N o +� O C 0 ,o u ti d ry 0 J Ln O vl O 0 0 0 O 0 O O V1 O 10 O - IT IT Ln Yl 10 10 n n m (ad) 4ada4 O V1 O vl O O V1 O Vl O V1 O Ln O U1 O N M M d d V1 IA 10 ID - n Q, (:U) 4adao O O ^ H 0 0/ c V c O o U -C T � � y vO v. zz m v a, fh 06 6 ❑ ❑ ❑ T = 72 U j c N 5 0 O O 0 a C c U V u v C r v u c V V N C C O N t U 0 C r r H y wif I� u u 059 Page 887 of ' N LF)94 N N N 0M Z V m p 3� a m" u m� m C 0 U L, Ln in L a W a 0) p J D W LL Q U 0 a V) � u m J Z J J � J � J CC W of a V) a V) t� �? W m V) 0 3 0 J Q U 0 0 0 W U > HLu " J CJ O 0 Z H a O IO C O U L LL a 0 o 1, o In o u o In o ; o . o � O I o M V Q In Ln l0 l0 N N m (1j) 44dad 0 O O u'i O Vl O 0 O In O to O ul O In O � O ti N N M M C R In In 10 10 N N x (13) 47dao 0 x ID w cz +1 N O J V1 O V1 O V1 O In O In O In O Ill O l!1 O •+ --� N N M M a V V1 In %D lD N N co (11) 41da4 w v N o Y x c 0 lD u 3 N O .. In O Vi O In O 0 O Vl O to O In O 0 lV M M tf 7 0 Ln l0 0 N N ?J (14) 41dad oL N a ON i JA C In O m O ul O In O 1n O m O Ul O 0 O — -+ N N en M tl V Ln y1 10 ID N N 00 (1)) 41daa Page 888 of 1 .. a 059 M OqI-4 N Z M o N " (V Z U 3.0 N rn a ca li m m C N OU m L a a W J W LL Q U O a o 1-4 V u m �Z O V7 Z D J � J o a ow a V) cc la 0 Z (D O Q D J U 0 U. O O W � 1"1 Q V > F: Z Lu F�1 J U O 0 z H a IO C O v LL c O u r`. v v v U Q a O In O In O U1 a In O In a In a In O In O rn R IT In Ill 10 10 n n co (1j) 41dad 0 O O In O In O In O In o In o Vl O In o In O M IT P In In IO 1C n N co (13) 41daQ O 00 0 w v O J ✓� G to O Vl O ul O Vi O ul O In O In O (11) 41daQ P N o � � c 0 N 0 Q Ifl O 4'1 O In O 0 O In 0 In O In O N 1 m R P 4'1 In 10 10 ()}) 41dao ID v In o In O In o In o In o In O In o In c 'Ni m P P In In ID 1p n n cc (1j) 41dao Page 889 of 1 P rn O N .. a In M rn rn N N O z n C 0 a W w 0 C n v El F- a 059 1 m Z 30 M Ou m a o V m m O m N iO � L a W a ti (� J F W N tL Q u O a p uu m �z O � J Z � H J p J c w 0.. kn a V1 M W m V) ce O 3 O J a u Z O tJ LL O O W 1 a u 9 H ui Lai J u TN l0 N 10 N N R N N t0 N t0 N O ►- oc b i a z a °O °pO a"� i a° i z a°p° a °° 13" r4 L �n 'A el iA N 'Vi 1n C Cy N w S Nd �ry'y O p v 0 Nb°� bb o "' Z v m b �o b Z z' ro N bb b -6 z �o a w_ 4 z P 7 > A zg 0 C"3 C�i�. <3 05 fn 0 O a to in > C3 Co t5 , c'3 to U �> u� � m L y -0 2 - D m 0 m N O V1 O 1n O 1n O U'1 O Vl 0 In O In O Vl O O 0 to 1D l0 n I, O O ID Z F- a 0 N 19 C 0 u U. C 0 v w v v v l (U) 41daQ 0 0 0 1n o 1n o 1n o 1n o 1n o u 0 ul o v o O tr In V1 1D 1D n n 00 (1d) 41dad O CO w 7 V7-W V V.. r., u N 1-TT 1TT� O u'. O ul O VI O ✓1 P 1 O ill O u1 O In O v ul ul 1D 1D n n m (11) 41dad w a N �C, 0 a 1D u LL N 0 0 LA O Vl O 0 O 0 O Jl O 0 O \n O 0 0 M v Ln In lD t0 n n `b (14) 41daa O In 0 vl O N O In O Vl O ul O 1n O V1 O - K In N 10 1D n n 0:1 (1W) 4adaQ 0 Em i a rn f`l M ry 0 N n, C v W u u 059 Page 890 of ' Page 1 \ CLP'ATII - ItARRIS C,HG > GEOLOGISTS 3AN Itit% OBISPO, C.% EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/23/22 BOREHOLE ID: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY- Gregg Drilling LOGGED BY: C. Springer (WSC) Q 5 4 40 e Lithologic Description (depth interval in feet) X x N (0-1) Artifical FBI (1-2) Clay (from CPT). ` X (2-4) Clayey Silt (from CPT). 5 (4-6) Sandy Silt (from CPT). (6-8) Silty Sand (from CPT). (8-12) Gravelly Sand with Clay; brownish yellow; fine to coarse sand; angular to subrounded, poorly sorted gravel to 1.5-inch diameter. 1 ) 10 YR 6i6 GM D (12-13) Clayey Sand with Gravel; brownish yellow; fine to coarse sand; gravel to 0.7-; 10 YR 6/6 SC A? inch diameter. (13-16) Sandy Clay trace gravel; dark yellowish brown: hard clay; mostly fine to medial l i - sand; trace coarse sand and fine gravel. l i p �-' R 4!4 C L' (16-19.5) Sandy Silt and Clayey Silt (from CPT, no sample rccovcry). X (19.5-20) Clayey Sand with Gravel; yellowish brown; coarse, subangular and angular ill ii ;; sand; fine gravel, soft clay. 10 1'R -5/8 SC, (20-24.5) Sandy Silt and Clayey Silt (from CPT; no sample recovery). Page 891 of 1059 10 YR 5/6 CL B-44 of 97 Page 2 / 3 C'.LEATH-IIARRIS C'HG GEOLOGISTS :AN LUIS OBISPO, C.% EXPLORATORY BORING LOG PROJECT: SL.O PCE DATE: 3/23/22 BOREHOLE 1D: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC) y a A a ? p a, rn 3 c U a, o L C7 Lithologic Description (depth inteval in feet) ' (24.5-28) Sandy Clay with Gravel; yellowish brown; soft to very soft clay, tine to coarse. subangular to subrounded, poorly sorted sand; fine, angular to subrounded gravel to . 10 YR 5/6 CL 0.9 (28-31.5) Sand (from CPT; no sample recovery). 30 N x 1.2 (31.5-32) Clayey Sand trace Gravel, brownish yellow; very soft clay; coarse, rounded to subrounded quartz, metavolcanic sand; fine, subrounded to rounded quartz, metavolcanic gravel clasts. 10 YR 6/6 SC /e, (32-36) Clay trace Sand; brownish yellow; very hard clay; trace fine sand. Ill YR 6/6 CL 35 0.2 (36-37) Sandy Silt and Clayey Silt (from CPT; no sample recovery). Y X (37-38) Clayey Sand trace Gravel, yellowish brown; very soft clay; coarse sand: trace 10 YR 6/6 SC subangular to subrounded gravel. (38-39) Sandy Clay; yellowish brown. soft clay; fine to medium, very well sorted sand. 10 YR 5/6 CL (39-40) Sandy Clay trace gravel; brownish yellow; soft to very soft clay, fine to coarse, 10 YR 6/6 CL 40 0.5 very poorly sorted, angular to subangular sand. 10 YR 5/6 CL (4041) Sandy Clay with Gravel, yellowish brown; soft to very soft clay; fine to coarse sand, angular to subangular gravel. 10 YR 6!6 CL (41-44) Clay trace sand: brownish yellow; firm clay; trace fine sand. 45 (44-45.5) Sand with Clay trace gravel; yellowish brown; mostly coarse, subrounded to subangular, moderately well sorted sand; trace tine gravel to 0.5-inch diameter. 10 YR 5!4 SP-SC (45.547) Clay trace Sand: brownish yellow; soft clay; trace mostly tine sand. 10 YR 6/6 CL (4748) Clayey Sand trace Gravel, brownish yellow; mostly coarse, rounded to 10 YR 6/8 SC 0.5 subangular, sand; hard clay, trace subrounded to rounded gravel to 0.75-inch diameter. x x (48-51.5) Sand (from CPT: no sample recovery). 50 Page 892 of 1059 B-45 of 97 Page 3 i 3 /fCnH4\rG.CLEATIf-IfARRIS > GEOLOGISTS i4.r L.UI[ 0815P0, C-,,k EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/23/22 BOREHOLE ID: B-21 SAMPLER TYPE: Macrocore MC5 LOCATION: El Mercado BOREHOLE DIAMETER: 2 25-inch DRILLING RIG: MARL 30-tan CPT push ring TOTAL DEPTH OF HOLE: 52 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC ) Lithologic Description a Ca r -a (depth inteval in feet) 3 X x \ (51,5-521 Clayey Sand trace Gravel; brownish yellow: mostly coarse. rounded to 10 YR 616 subangular, sand: hard clay; trace subrounded to rounded gravel to 0.75-inch diameter. (52-57) Mostly Sand (from CPT). 55 C e 1 went to S I beet. Witter Sample was collected at >b teet. Direct Push refusal at 52 feet Page 893 of 1059 B-46 of 97 Page I ; �t'.L.F:ATH-f1ARftIS GEOLOGISTS FAN tuts OBISPO. CA EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/31/22 BOREHOLE ID: B-24 SAMPLER TYPE: Macrocore MC5 LOCATION: Prado Road BOREHOLE DIAMETER: 2.25-inch DRILLING RIG: MARL 30-ton CPT push rig. TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WS0 Lithologic Description (depth interval in feet) 3 X X \ (0-I) Artifiieal Fill (asphalt/road base) (1-2) Clayey Silt (from CPT). ` (2-4) Sandy Silt (from CPT). (4-6) Silty Clay (from CPT). (6-8) Clay (from CPT). lil (8-16) Clay trace sand; yellowish brown; hard clay; trace fine to coarse, subr� undrd >and / 10 YR 5/6 CL I� (16-17) Clay and Silty Clay (from CPT; no sample recovery). h X (17-17.5) Clay trace Sand; yellowish brown; soft to fine clay: trace fine to coarse sand. 10 YR 5/6 CL 10 YR 5/6 CL (17.5-20) Sandy Clay trace Gravel; yellowish brown, very hard clay; fine to coarse, poorly sorted sand; trace subangular to subrounded gravel to 0.5-inch diameter. 2l) (20-23) Clay trace Sand; yellowish brown; hard clay; trace subrounded and subangular, very well sorted coarse sand. i u 1'R 5/6 CL (23-23.5) Sandy Clay trace gravel; brownish yellow; firm clay; fine to coarse sand; truer fine subrounded to subangular shale and metavolcanic gravel. (23.5-24) Gravelly Clay with Sand: brownish yellow; soft to firm clay; fine to coarse 10 YR 6/8 CL sand: fine subrounded gravel. X x X (24-26) Sandy Silt and Clayey Silt (from CPT: no sampler - �. e v Y% � �94 of 1059 B-47 of 97 Page 2 / 3 <CHG CL EATIf- IfAItRIS 7= GEOLOGISTS AN tUls OBISPO. CA EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/31/22 BOREHOLE ID: B-24 SAMPLER TYPE: Macrocore MC'5 LOCATION: Prado Road BOREHOLE DIAMETER: 225-inch DRILLING RIG: MARL 30-ton CPT hush rig. TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. springer (WSC) Lithologic Description (depth interval in feet) (26-27) Sandy Clay trace gravel; yellowish brown; firm clay; fine to coarse sand; fine X subrounded gravel. l0 YR 5/8 CL ,.'� (27-28) Gravelly Clay with Sand, brownish yellow; very hard clay; fine to coarse 10 YR 6/6 CI_ sand; subangular to rounded gravel to 0.75-inch diamater. (28-31) Clay and Silty Clay (from CPT; no sample recovery). X ail - (31-32) Clayey Gravel with Sand; dark yellowish brown, firm clay; fine to coarse 10 YR 4/6 GC o �r sand; subangular to subrounded. mostly volanic gravel clasts to 0.75-inch diameter. \ \ (32-34) Clay and Silty Clay (from CPT; no sample recovery). (34-39) Clayey Gravel with Sand; yellowish brown; soft clay; fine to coarse sand. • fine, subrounded to subangular volcanic, shale, metavolcanic gravel to 0.5-inch diameter. 10 YR 5/8 GC �' • ` • • (3940) Clayey Sand with Gravel; brownish yellow; soft clay, fine to coarse sand: 10 YR 6/8 SC tine, subrounded to subangular volcanic, shale, quartz gravel to 0.5-inch diameter. 4) (4042) Sandy Silt (from CPT; no sample recovery). X X X (4243) Clayey Sand with Gravel; brownish yellow, soft clay; fine to coarse sand. 10 YR 6/8 SC fine, subrounded to rounded volcanic and quartz gravel to 0.5-inch diameter. (4345) Clayey Sand with Gravel; yellowish brown; soft to very soft clay; fine to I 0 YR 5/8 SC coarse, poorly sorted sand: subrounded to angular volcanic, shale, and chen gravel to 0.5 inch diameter. -1 (4547) Sandy Clay trace gravel; yellowish brown; firm clay; fine to coarse sand; tract 10 YR 5/8 Cl- subangular to subrounded fine gravel. (4748) Sandy Clay; brownish yellow: very hard clay; mostly fine to medium sand, iracc 10 YR 6/8 CL coarse sand. (48-50) Sandy Silt and Clayey Silt (from CPT; no sample recovery). x a ,(I Page 895 of 1059 10 YR 5/8 Page 3 / 3 / \CLEATII-IIAKRIN CHG `> GEOLOGISTS SAN tuts O813PO, CA EXPLORATORY BORING LOG PROJECT: SLO PCE DATE: 3/31/22 BOREHOLEID: B-24 SAMPLER TYPE: Macrocore MC5 LOCATION: Prado Road BOREHOLE DIAMETER: 225-inch DRILLING RIG: MARL 30-ton CPT push rig TOTAL DEPTH OF HOLE: 60 feet DRILLING COMPANY: Gregg Drilling LOGGED BY: C. Springer (WSC) Lithologic Description (depth interval in feet) 55 60 65 0.0 0.0 10 YR 5/8 C (50-50.5) Clayey Sand with Gravel; yellowish brown; soft clay; fine to coarse. subangular to subrounded, poorly sorted sand; gravel to 0.6-inch diameter. (50.5-52) Sandy Clay; brownish yellow; very hard clay; mostly tine to medium sand. (52-56) Clayey Sand with Gravel; brownish yellow; soft clay; tine to coarse, subrounded to rounded, poorly sorted sand; subrounded to subangular, sliale and volcanic gravel clasts to 0.8-inch diameter. (56-60) Clay trace sand; brownish yellow; soft clay; trace mostly fine sand. (60-66) Sandy Silt (from CPT). CPT went to 66 feet. Water Sample was collected at 63 feet. Direct Push refusal at 60 feet 10 YR 6/8 CL 10 YR 6/8 SC A 10 YR 6/8 CL Page 896 of 1059 B-49 of 97 <� NEFR tr 3�—w„ N Wd —Z — 03LLOld 3WLL 5ZOZ 5Z LL G— 03LLOld ava SN3A rG— 3WtlNtl n ,, � S $ °V ¢ w 'O w OLLJ J b J = LLJ 'o o a g< a i w as mum k N J w m Om 60 gF �L a` H'c J < - O O W to M �' UJ a5� et O n Q N m Z N N ¢ i O o C1.4 O I W W o N 2 O tlso ] N 133diS V83nolH Hinos i J 59 a� �N I eH°Lx EER � Wd —Z - O3l101d 3WLL SZOZ SZ LL G- —Old ava SN3AMKM'G- 3W—sn I a X I LLJ a6 o � LLJ W �b3 C O U O ''p� SL 83 W fn Z s ELEVATION (FEET) Woc a o h o o S < Ng s� M 0 o a M a w Eko o W 91 g ° Q H - E O - x if - p 0o O J LLl II p o A- _j d' Ni IL m O W E E n E as N >O U JE 2 0 Z _ > a g Y n Q O m u '- - o m Y crag o m E of ECz'o d UPEz�gE Ly O o. •m m _oS o u " o .vaa £'69+ZII '-IS 11 ,9.6l ° d O m H m O O C U 7 o.°- K( % 00 J w N 3 O TY O O Z " Q W O � a _ _ _ i• _ W vi Lo � ro V _ E - Z e E E -- N E c o N N E EU N m ; E 9 Ed a �m _ - c 3 v A E v�i a Su E- _ alT L gE o f aUo'N n _� 9 0. tOn tO m 'Lrn C a m m m M y o - - c°5 E E o X L O 2v V C OL L .Nn rad 5 ; v' C Z'69+i 1 I '^IS 'Ia .9'01 e N a 6\° E N OR rc - N % M O •_ _ Viao°+ V •- � c 0.... c ooao m N 3 ° o a x ° c 3 a rave B 3wv " av no, r E "6z 433J) NOI1VA313 d g E M ° w o to m:-a a v o d T �a+t; a N n c v 0 0 i cv N L E 1 E N C N r N Nn�M D_ M E. Y U(^00�0 �1Q N U 0 t0 n< Z Mt2 r�OZ W V M o c Y W pp NNE �'t Z o a° Mi`41ZW>= Page )59 b ELEVATION (FEET) to � 8 a q0 in o_ LJ II II - VRn EU d' IV F E E d O > iEE E E E o E E E LME E � cYg+ E c/1Yg+ eJ�Jz - E iJ`n J= /IE /15 /Iz /1z /4I =I N O. Mnmm pMp Y M > Q M M Z00 Z W p p N N t m Mi`41z W>2 E _ Ei w E _ ¢z E E E I I /Ir I I I I I I I (1333) N011YA313 o a p L1J p o .o L L� °c U O a@p o d U LJJ (� °s a .� Li Z o`c . J O M o E V m V D m I o o O a v q a ` N L, O P a c p C 0 o , CD o q U Q 0 E o m J � L a a N p w = N U zq m ? o ] m O Q p c ai O o o o m a x e ¢ o o p c V c ° E � 3 Q O N c rn a o a_ ¢ a <a a a w a a N _ O O U o J O N p _ O O U - C Mo€W U U 7 o 0 o O J a c o N J.+ ° W Z y ¢n ¢ (n a w o z 0 E q y v_ 0 '3 � 3 � O L V c U N U N m E p U q C V O N O p O p m M � -og % q N q p 5 W 9 n •- 9 q C E V N N O I � m M I - q � m O qM p O •- _ 0 O c L c Q 0 O O E q I N O ; rc 9 x oa a p � t o A 0. M rn I'd c y v Z m ; O N a E N E m m O E N p mL 0 U q q O. c O a p cv O S rn« Q p a t y 5 H O Z o d Page 059 �N I eH°Lx EER � Wd —Z - ml101d 3WLL SZOZ SZ LL G- —Old 3Ltl0 SN3AMK11'G- 3mNtl35N o X I tl s g ir p o z W x o c ° !E0 LJJ �o V' c o ° J ag� O � zire o x i Q a ELEVATION (FEET) oo' 'o Ld U g% rl Lu g o Q C ° `o 0 o c - O i O O m U 0 Q (' U O C O a N ✓ Q 0 - L� O y v m 3 d IL a o W O =O U JE 2 0 Z _ > Tn E 30 9 O g x c o- E o a c o o {c e E Q - c Lm c 3 f ti.E iL y a O m � c w :E V } �aE �E E_��a�-.r-.r O 3 _o d 2 laJ Q ry cL m_ _ 61� ad a om „vaa. 6'o9NI I ^IS '18 ,0'O3 E� c d .. N - - m eO 0 &B r o- y _ E 3— cc—Eccc - EPNY .E ° U tin .z, N O E aE.- z, c E � Eo N a di N E % E c� E V E c 3N 0CEU O O r` -- u a 3=- - Lm PP 0 U m x ME mQ y 5 Ef c ,c. vwiuc c ,•' c .- v z��'- o LO ._ O0 /Ywg)m of Ic I7' I I I I I IE I( ;i'� I' ;o�� d c I ao E� N � � c a as d o � eufl Vad 6'99+911 'o1S 'la ,6£91 ------------ c I v' o OMaO d N N p O m B ,-Fp v rn 3 m � a n v y 0 0 0- 3 O ° KO �U c j - (1331) NOIIVA313 ? rnv`r a mcv 6 V v m 0 p 3 0 a c '�v o m N N Nn�M a m p 1H.0 7 - C c r k D _ M m 6>< <L� p e C! e o Y U(00t0 m m 0 n< Z W V M o Y L.j t2cO oZ N N i[ c o W O p �'t m MZW>= Z Page 91 )59 �N I eH°Lx EER � Wd —Z - O3l101d 3WLL SZOZ SZ LL G- —Old 3Ltl0 SN3AMK11'G- 31WNtl35N o X I o�tl s c a C Z ^ XI o °I c w W O U do z= a c W � s k X 8 tl S g z o J C� G_ I i3 o e N p ¢ J o O m �Im ry o o a Ally ° ,Q E�'g � ELEVATION (FEET) w g O o Q H ✓a - o a v m a c to m O�� W' a o `o O c - °m O in in o° U m O J - L� � d rn d L •3 O a o N IL F d O o ° w = V O _ 2 O Z _ ° O -° o o a a 0 + N a 0 O_ O m d E Z m O c d c m 4 o a a m x d O n m d V q ro° `o O Bull 91H c j o o m ~ w cn O 0'££+SS 'RIS 'Itl ,S'lZ _ c o U o o :w w N 0 - - = o = 3 O N O yl w c Z O N d Fa Q N Q N wC> o, o, w ui ro r ao a� a (1333) NOliVA313 ELEVATION (FEET) o y m oo m �5 y m °m m a n` �� c .I y o o `m •; � N m oa m o o �o < m E m u m R oL'y m m C M Q 0' w O t°i1 FpF E Z O N3 C d a m C c O C da w � ° C m N m V1 �•_ ° N O W a U o _ rn u •3 � rn E o m I N ; o � x y C p •N H .N.. o zo q t N ., m m B m N m m N E W E m N o (133J) NOliVA313 a o g N a c - ' o m Ll U m y o 0 E o m a N'o a a :6 6 •_ ° c g m (7 �_ Mnp�p OMp 'oa a V L Y U(^°a�D >Q Z Z (n m o e e t 8 9 M M OOOO N M Y W O NNE �'t co M�wzw>= Z Page o oi< i n csi cgi H E - i O I - soli tlNd N�x 0'S9+LII '^IS 'll ,9'IZ _ - E 59 GROUP SYMBOLS AND NAMES Graphic / Symbol Group Names Graphic / Symbol Group Names Well -graded GRAVEL Lean CLAY GIN Lean CLAY with SAND Well -graded GRAVEL with SAND Lean CLAY with GRAVEL CL SANDY lean CLAY SANDY lean CLAY with GRAVEL co 00 Poorly graded GRAVEL O o GP GRAVELLY lean CLAY O o e 0 0 Poorly graded GRAVEL with SAND GRAVELLY lean CLAY with SAND Well -graded GRAVEL with SILT SILTY CLAY GW-GM SILTY CLAY with SAND WeGRAVEL with SILT and SAND SILTY CLAY with GRAVEL CL-MIL SANDY SILTY CLAY • Well -graded GRAVEL with CLAY (or SILTY CLAY) SANDY SILTY CLAY with GRAVEL . GW-GC Well -graded GRAVEL with CLAY and SAND GRAVELLY SILTY CLAY (or SILTY CLAY and SAND) GRAVELLY SILTY CLAY with SAND o� Poorly graded GRAVEL with SILT SILT O GP -GM SILT with SAND O Poorly graded GRAVEL with SILT and SAND SILT with GRAVEL ° MIL SANDY SILT SANDY SILT with GRAVEL �o O Poorly g GRAVEL with CLAY SILTY graded O O GP -GC (or Poorly graded GRAVEL with CLAY and SAND GRAVELLY SILT o (or SILTY CLAY and SAND) GRAVELLY SILT with SAND SILTY GRAVEL ORGANIC lean CLAY GM ORGANIC lean CLAY with SAND O SILTY GRAVEL with SAND ORGANIC lean CLAY with GRAVEL OL SANDY ORGANIC lean CLAY SANDY ORGANIC lean CLAY with GRAVEL CLAYEY GRAVEL GC GRAVELLY ORGANIC lean CLAY p a CLAYEY GRAVEL with SAND GRAVELLY ORGANIC lean CLAY with SAND O SILTY, CLAYEY GRAVEL ORGANIC SILT GC -GM ORGANIC SILT with SAND O SILTY, CLAYEY GRAVEL with SAND ORGANIC SILT with GRAVEL OL SANDY ORGANIC SILT SANDY ORGANIC SILT with GRAVEL Well -graded SAND SW GRAVELLY ORGANIC SILT Well -graded SAND with GRAVEL GRAVELLY ORGANIC SILT with SAND Poorly graded SAND Fat CLAY Sp Fat CLAY with SAND Poorly graded SAND with GRAVEL Fat CLAY with GRAVEL CH SANDY fat CLAY Well -graded SAND with SILT SANDY fat CLAY with GRAVEL SWSM GRAVELLY fat CLAY Well -graded SAND with SILT and GRAVEL GRAVELLY fat CLAY with SAND Well -graded SAND with CLAY (or SILTY CLAY) Elastic SILT SW -SC Elastic SILT with SAND Well -graded SAND with CLAY and GRAVEL Elastic SILT with GRAVEL (or SILTY CLAY and GRAVEL) MH SANDY elastic SILT Poorly graded SAND with SILT SANDY elastic SILT with GRAVEL SPSM GRAVELLY elastic SILT Poorly graded SAND with SILT and GRAVEL GRAVELLY elastic SILT with SAND Poorly graded SAND with CLAY (or SILTY CLAY) ORGANIC fat CLAY SPSC ORGANIC fat CLAY with SAND Poorly graded SAND with CLAY and GRAVEL ORGANIC fat CLAY with GRAVEL (or SILTY CLAY and GRAVEL) OH SANDY ORGANIC fat CLAY SILTY SAND SANDY ORGANIC fat CLAY with GRAVEL SM GRAVELLY ORGANIC fat CLAY SILTY SAND with GRAVEL GRAVELLY ORGANIC fat CLAY with SAND CLAYEY SAND ORGANIC elastic SILT SC ORGANIC elastic SILT with SAND CLAYEY SAND with GRAVEL ORGANIC elastic SILT with GRAVEL OH SANDY elastic ELASTIC SILT SILTY, CLAYEY SAND SANDY ORGANIC elastic SILT with GRAVEL SCSM GRAVELLY ORGANIC elastic SILT SILTY, CLAYEY SAND with GRAVEL GRAVELLY ORGANIC elastic SILT with SAND ORGANICSOIL PT PEAT ORGANIC SOIL with SAND — ORGANIC SOIL with GRAVEL OUGH SANDY ORGANIC SOIL SANDY ORGANIC SOIL with GRAVEL COBBLES COBBLES and BOULDERS GRAVELLY ORGANIC SOIL BOULDERS GRAVELLY ORGANIC SOIL with SAND DRILLING METHOD SYMBOLS Auger Drilling H ® Dynamic Cone Rotary Drilling a or Hand Driven ® Diamond Core FIELD AND LABORATORY TESTS C Consolidation (ASTM D2435) CL Collapse Potential (ASTM D5333) CP Compaction Curve (ASTM D1557) CR Corrosion, Sulfates, Chlorides (CTM 643; ASTM D4972, ASTM G187, ASTM D4327) CU Consolidated Undrained Tiiaxial (ASTM D4767) DS Direct Shear (ASTM D3080) El Expansion Index (ASTM D4829) M Moisture Content (ASTM D2216) OC Organic Content (ASTM D2974) P Permeability (ASTM 5084) PA Particle Size Analysis (ASTM D422-63 [2007]) PI Liquid Limit, Plastic Limit, Plasticity Index (ASTM D4318) PL Point Load Index (ASTM D5731) PM Pressure Meter PP Pocket Penetrometer R R-Value (CTM 301) RS Torsional Ring Shear (ASTM D6467) SE Sand Equivalent (CTM 217) SG Specific Gravity (AASHTO T 100) SL Shrinkage Limit (ASTM D427) SW Swell Potential (ASTM D4546) TV Pocket Torvane UC Unconfined Compression - Soil (ASTM D2166) Unconfined Compression - Rock (ASTM D7012) UU Unconsolidated Undrained Triaxial (ASTM D2850) UW Unit Weight (ASTM D4767, ASTM D7263) VS Vane Shear (AASHTO T 223-96 [20041) -200 200 Wash (ASTM D1140) SAMPLER GRAPHIC SYMBOLS ® Standard Penetration Test (SPT) (2" O.D.) mStandard California Sampler (2.5 O.D.) eModified California Sampler (Y O.D.) TShelby Tube M Piston Sampler Rock Core Grab Sample Bulk Sample Other (see remarks) WATER LEVEL SYMBOLS a First Water Level Reading (during drilling) Y Static Water Level Reading (short-term) 1 Static Water Level Reading (long-term) NYeh and Associates, Inc. Geotechnical to Geological • Construction Services REPORT TITLE LEGEND FOR SOIL CLASSIFICATION PROJECT NAME Prado Road Bridge Widening DATE 10/1 SHEET B-55 of 97 ROCK GRAPHIC SYMBOLS ® IGNEOUS ROCK ® SEDIMENTARY ROCK METAMORPHIC ROCK BEDDING SPACING Descriptor Thickness or Spacing Massive > 10 ft Very thickly bedded 3 to 10 ft Thickly bedded 1 to 3 ft Moderately bedded 3-5/8 inches to 1 ft Thinly bedded 1-1/4 to 3-5/8 inches Very thinly bedded 3/8 inch to 1-1/4 inches Laminated < 3/8 inch WEATHERING DESCRIPTORS FOR INTACT ROCK Diagnostic Features Chemical Weathering -Discoloration -Oxidation Mechanical Weathering Texture and Solutioning and Grain Boundary Body of Rock Fracture Surfaces Texture Solutioning Descriptor Conditions General Characteristics Fresh No discoloration, not oxidized No discoloration No separation, intact No change No solutioning Hammer rings when crystalline or oxidation (tight) rocks are struck. Slightly Discoloration or oxidation is Minor to complete No visible separation, Preserved Minor leaching of Hammer rings when crystalline Weathered limited to surface of, or short discoloration or intact (tight) some soluble rocks are struck. Body of rock distance from, fractures- some feldspar crystals are dull oxidation of most surfaces minerals may be noted not weakened. Moderately Discoloration or oxidation All fracture Partial separation of Generally Soluble minerals Hammer does not ring when Weathered extends from fractures usually surfaces are boundaries visible preserved may be mostly i rock is struck. Body of rock s throughout; Fe -Mg minerals discolored or leached slightly weakened. are "rusty' ; feldspar crystals oxidized are "cloudy" Intensely Discoloration or oxidation All fracture Partial separation, rock is Altered by Leaching of Dull sound when struck with Weathered throughout; all feldspars and surfaces are friable; in semi -arid chemical soluble minerals hammer; usually can be broken Fe -Mg minerals are altered to discolored or conditions, granitics are disintegration may be complete with moderate to heavy manual clay to some extent; or oxidized- surfaces disaggregated such as via pressure or by light hammer chemical alteration produces in situ disaggregation (refer to are friable hydration or argillation blow without reference to planes of weakness such as incipient or grain boundary conditions) hairline fractures or veinlets. Rock is significantly weakened. Decomposed Discolored of oxidized Complete separation of Resembles a soil; partial or Can be granulated by hand. throughout, but resistant rain boundaries ?disaggregated) complete remnant rock structure Resistant minerals such as minerals such as quartz may may be preserved; leaching of quartz may be present as "dikes". be unaltered; all feldspars and soluble minerals usually stringers' or Fe-Mq minerals are complete completely altered to clay Note: Combination descriptors (such as "slightly weathered to fresh") are used where equal distribution of both weathering characteristics is present over significant intervals or where characteristics present are "in between" the diagnostic feature. However, combination descriptors should not be used where significant identifiable zones can be delineated. Only two adjacent descriptors shall be combined. "Very intensely weathered" is the combination descriptor for "decomposed to intensely weathered". CORE RECOVERY CALCULATION (%) E Length of the recovered core pieces (in.) x 100 Total length of core run (in.) ROD CALCULATION (%) E Length of intact core pieces > 4 in. x 100 Total length of core run (in.) 1A ROCK HARDNESS Descriptor Criteria Extremely Hard Specimen cannot be scratched with pocket knife or sharp pick; can only be chipped with repeated heavy hammer blows Very hard Specimen cannot be scratched with pocket knife or sharp pick; breaks with repeated heavy hammer blows Hard Specimen can be scratched with pocket knife or sharp pick with heavy pressure; heavy hammer blows required to break specimen Moderately Specimen can be scratched with pocket knife or sharp pick with light or moderate Hard pressure; breaks with moderate hammer blows Moderately Soft Specimen can be grooved 1/6 in. with pocket knife or sharp pick with moderate or heavy pressure; breaks with light hammer blow or heavy hand pressure Soft Specimen can be grooved or you ed with pocket knife or sharp pick with light pressure, breaks with light to moderate hand pressure Very Soft Specimen can be readily indented, ggrooved, or gouged with fingernail, or carved with pocket knife; breaks wtf light hand pressure FRACTURE DENSITY Descriptor Criteria Unfractured No fractures Very Slightly Fractured Lengths greater 3 ft Slightly Fractured Lengths from 1 to 3 ft, few lengths outside that range Moderately Fractured Lengths mostly in range of 4 in. to 1 ft, with most lengths about 8 in. Intensely Fractured Lengths average from 1 in. to 4 in. with scattered fragmented intervals with lengths less than 4 in. Very Intensely Fractured I Mostly chips and fragments with few scattered short core lengths REPORT TITLE LEGEND FOR ROCK CLASSIFICATION Yeh and Associates, Inc. PR aJECT NAME do Road Bridge Widening Geotechnical • Geological • Construction Services DATE SHEET 10/10/2024 r-1--- n -A -M B-56 of 97 'a c'4 N N N N m J Z Q 0 N N LOGGED BY BEGIN DATE COMPLETION DATE HAMMER TYPE BORING NUMBER R. Hooke 1/18/22 1/19/22 140-lb Autotrip 22RC-01 FINAL BY BOREHOLE LOCATION (Lat/Long or North/East and Datum) SURFACE ELEVATION J. King --/-- 139.0 ft DRILLING METHOD BOREHOLE LOCATION (Offset, Station, Line) WEATHER NOTES 4" SSA/Mud Rotary/3.75" HQ Core 10.50' Rt. Sta. 112+69.2, "PRA" Line Cool, partly cloudy DRILLER LOCATION DESCRIPTION BACKFILLED WITH Geo-Ex Subsurface Exploration West side of bridge,10' west of fence Monitoring Well DRILL RIG GROUNDWATER DURING DRILLING AFTER DRILLING (DATE) TOTAL DEPTH OF BORING CME 55 Track -Mounted Rig READINGS 20.5 ft See Report I 1 100.0 ft C L t C ° Z m C0 co 0 o m c -0 L E ° DESCRIPTION 8 E a T o �,` Remarks w a a)n o�aZ 3 3 0 0 "o ❑ W W (p 20 N O N j O O N ('� •p p �` U Lin = N >N T' ASPHALT CONCRETE. Grouted Solinst Level Logger installed on 1 to top 1/20/2022 6" AGGREGATE BASE. SANDY lean CLAY (CL); brown; moist; A few to little GRAVEL; (ALLUVIUM). 137 2 3 135 4 5 Hard. -200 (13% G, 37% S, 50% F) 1 5 17 100 17 98 ;;4 _5PP 6 133 6 11 7 131 8 CLAYEY GRAVEL with SAND (GC) brown; moist. 9 00 0 129 10 Loose; fine to medium, subrounded to -200 (29% G, 27% S, 44% F) 2 8 13 78 12 2.75PP o subangular GRAVEL. 5 PI (42 LL, 19 PL, 23 PI) 11 ° 8 127 12 ° 13 O ° 0 0 125 14 15 0 — ---- CLAYEY GRAVEL (GC); medium CR �H = 6.93, r = 722 ohm -cm, 3 9 21 100 25 98 dense; brown; moist; fine to medium, 8 SO4 = 40 mg/kg, Cl- = 15 mg/kg) 123 16 a , o subangular GRAVEL. 13 Bentonit Chips 17 0 121 18 ° 19 90A 119 20 CLAYEY SAND with GRAVEL (SC); Switched to mud rotary 4 2 13 100 medium dense; brown; moist; fine to 5 21 :: medium, subangular to subrounded 8 GRAVEL. 117 22 Sand around 23 slotted screen 115 24 25 (continued) PROJECT NAME T Yeh Associates, Inc. Prado Road Bridge Widening UMBER and 216 323 BORING NUMBER Geotechnical • Geological • Construction Services 22RC-01 REVISION DATE SHEET 9/12/2022 B-57 of 97 ZO Lu J 113 111 109 107 105 103 101 99 97 95 93 91 89 87 85 W 2b 2g 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 F L f6� i0 DESCRIPTION CLAYEY SAND with GRAVEL (SC) (continued). _ _ _ _ SANDY lean CLAY (CL); medium stiff; brown. Stiff. Very stiff; trace fine to medium, subrounded GRAVEL. 3 Of fl= N VO (nJ a`> iZ CC 7 X 5 C (0 a N CO 3 10 15 O w o. N coca 25 p O N W 100 o C� W a,' O a) 00 2Uo8 32 L a) C �' 90 L c 8 aS L V) (n 0.75PP O r 2, 0)0 = o E m a1 C O °- a)W Remarks CU -200 (0% G, 44% S, 56% F) PI (39 LL, 20 PL, 19 PI) CR (pH = 7.00, r = 1,444 ohm -cm) 6 5 8 9 17 94 29 1.75PP 7 11 18 38 56 100 26 99 3.5PP METASEDIMENTARY ROCK (CLAYSTONE); brown; decomposed; very soft; black and tan chips; (FRANCISCAN MELANGE). Intensely weathered; soft. (continued) 8 7 12 13 25 61 REF/4 10 40 5 0/5" 50/5, 100 Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22R - 1 REVISION DATE 9/12/2022 SHEET B-58 of 97 ZO i J W ~ W O L co P (7 DESCRIPTION 3 Of 0 d O N U0 cn J a`> 0 F= i Z CC 7 X C (0 a N O CO O w o N O m p O N of o C� a,' O N 0 0 C) L a) ., C o a L c aS L V) U) O r C = E m CJ a1 C O °- N Remarks 83 81 79 77 75 73 71 69 67 65 63 61 59 57 55 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 Black; moderately weathered; moderately soft. METASEDIMENTARY ROCK (Claystone) (continued). Intensely weathered; intenselyy fractured; clay seams up to 1/4". Fracture plane at 65 degrees. METASEDIMENTARY ROCK (GRAYWACKE); gray; intensely weathered; modderately soft; intensely to moderately fractured; clay infill fractures. Weathers to sandy lean CLAY (CL), vertical trace fractures with iron stains and calcite. Highly sheared zone, closed fractures. METASEDIMENTARY ROCK (CLAYSTONE); black; very soft; very intensely fractured; very sheared, clay matrix - hard. Block of GRAYWACKE SANDSTONE from 73 to 73.5. Clay matrix - hard. Intensely weathered; very sheared. (continued) 150/4" REF/4" 26 102 ' .:_'... ' Sand to bottom of hole Switched to Wireline Coring CU UU UC UC 25 19 9 12 114 127 124 4.5PP >4.5PP 4.5PP Q Q Q Q Q Q Q Q Q Q Q Q Q 2 88 62 3 100 78 4 100 68 5 100 24 6 100 56 7 92 30 Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22R - 1 REVISION DATE 9/12/2022rlr)r SHEET B-59 of 97 N ZO i J W 53 51 49 47 45 43 41 ~ W ❑ 85 86 87 88 89 90 91 g2 93 94 95 96 97 98 99 m L coP 2 U DESCRIPTION METASEDIMENTARY ROCK (Claystone) (continued). Block of GRAYWACKE SANDSTONE from 86.5 - 88.5. METASEDIMENTARY ROCK (GRAYWACKE); some 2 - 4" blocks, very intensely sheared zones. Gray; intensely to moderately weathered; moderately fractured. 1/2" clay seam, closed fractures. 3 Of C d O E�� fn J a`> i Z 7 X 7 ❑ (0 a N O CO O w o N O c0 p O N W 92 o C7 30 a,' ON 00 U❑ L a) �'U a L c aS L N (n O r C = ❑ 0 0 0 E m ❑ a1 . .':. '.. . ' C O °- ❑ N Remarks UC 8 94 38 9 94 35 10 31 31 39 37 35 33 31 29 27 25 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 11 Bottom of borehole at 100.0 ft bgs This Boring Record was developed in accordance with the Caltrans Soil & Rock Logging, Classification, and Presentation Manual (2010) except as noted on the Soil or Rock Legend or below. T Yeh and Associates, Inc. Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening 216 323 UMBER BORING NUMBER 22RC-01 REVISION DATE 9/12/2022 SHEET B-60 of 97 LOGGED BY BEGIN DATE COMPLETION DATE HAMMER TYPE BORING NUMBER R. Hooke 1-19-22 1-20-22 140-IbAutotrip 22RC-02 FINAL BY BOREHOLE LOCATION (Lat/Long or North/East and Datum) SURFACE ELEVATION J. King --/-- 139.0 ft DRILLING METHOD BOREHOLE LOCATION (Offset, Station, Line) WEATHER NOTES 4" SSA/Mud Rotary/3.75" HQ Core 16.30' Rt. Sta. 114+56.9, "PRA' Line Sunny, warm DRILLER LOCATION DESCRIPTION BACKFILLED WITH Geo-Ex Subsurface Exploration East side of bridge, 10' south of ETW Grout DRILL RIG GROUNDWATER DURING DRILLING AFTER DRILLING (DATE) TOTAL DEPTH OF BORING CME 55 Track -Mounted Rig I READINGS Not measured 91.0 ft z0 o a5 _ L 0 E CD o o L (D w rn w Q = DESCRIPTION j CD a a o o �,. > _ t N g N o Remarks w H a L m 0. E E 3 3 0 .�. N c D w 2 0 in in m m tY 2 U in �- U :YN 0 U) 0 0 8" ASPHALT CONCRETE. 1 6" AGGREGATE BASE. CLAYEY SAND with GRAVEL (SC); brown and red; B 137 2 moist; fine to medium, subangular GRAVEL; red color possibly decomposed bricks; (ARTIFICIAL FILL). 3 135 4 5 CR (pH = 6.69, r = 1,257 ohm -cm) CLAYEY SAND with GRAVEL SC); medium dense; 12 8 26 100 9 110 dark brown; moist; (ALLUVIUM. 12 133 6 14 7 131 8 9 129 10 :•; Very loose. 13 P 2 83 P 11 2 127 12 13 125 14 15 Lean CLAY with SAND (CL); very stiff; brown; moist; CR �H = 7.30, r = 602 ohm -cm, 14 7 36 100 22 102 4.OPP trace fine GRAVEL. 15 SO4 = 81 mg/kg, Cl- = 7 mg/kg) 123 16 21 17 121 18 19 119 20 200 (1 % G, 23% S, 76% F) 15 4 15 100 2.5PP 7 PI (45 LL, 17 PL, 28 PI) 21 8 117 22 23 115 24 25 (continued) PROJECT NAME Yeh Associates,Inc.216 I Prado Road Bridge Widening UMBER and 323 BORING NUMBER Geotechnical • Geological • Construction Services 22RC-02 REVISION DATE SHEET 9/12/2022 B-61 of 97 Z o `m _ {�pp U E C p c i 0) L 0 o _ �+ DESCRIPTION Z CO a w n L, o � ._ ` °' °' o Remarks > H L p• to N 0 3 N D f6 C C LI 20 ui (A o0 00 W W 2 U C, n cn Y o L) 2b CLAYEY SAND (SC); loose; brown. 16 5 15 100 28 94 7 113 26 8 27 111 28 29 109 30 Lean CLAY with SAND (CL); very stiff; red brown -200 (0% G, 20% S, 80% F) 17 4 19 100 2.75PP 8 31 11 107 32 33 105 34 35 CLAYEY SAND (SC); medium dense; brown; fine to 18 8 27 100 28 96 coarse SAND. 12 103 36 15 37 101 38 1 39 99 40 Lean CLAY (CL); medium stiff; red brown. -200 (0% G, 9% S, 91% F) 19 3 10 100 1.OPP 5 PI (45 LL, 22 PL, 23 PI) 41 5 97 42 43 95 44 45 Stiff. CU 20 8 26 100 24 102 1.5PP 12 93 46 14 47 91 48 49 89 50 Hard; brown. 21 12 49 100 >4.5PP 21 51 28 87 52 53 85 54 55 (continued) PROJECT NAME Yeh Associates, Inc. Prado Road Bridge Widening PROJECT UMBER and 216-323 BORING NUMBER Geotechnical • Geological • Construction Services 22Rc-02 REVISION DATE SHEET 9/12/2022 B-62 of 97 Z W _ H o �+ L g 0 DESCRIPTION o `5 _ {�pp U E Z p. co (A C CO a N m p -0 n 03 m c Z' 0 W o o � N -55 L) i 0) ._ C o n L 0 ` - CU to Y o °' CM 0 °' o Remarks C c) 83 81 79 77 75 73 71 69 67 65 63 61 59 57 55 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 SANDY lean CLAY with GRAVEL (CL); hard; brown; fine to medium, subangular GRAVEL. ---------------- SANDY lean CLAY (CL); hard; brown. 22 24 31 50/1" 81/7" 100 21 103 4.5PP UC CU 23 29 90/12"100 40 50/6" >4.5PP METASEDIMENTARY ROCK (CLAYSTONE); black/brown; intensely weathered; soft; very intensely fractured; with 4 to 6 inch blocks of GRAYWACKE; (FRANCISCAN MELANGE). Black/gray; 35 to 65 degree fractures, 1" seam of soft clay. 45 degree fracture. GRAYWACKE block from 67' to 68'. METASEDIMENTARY ROCK (GRAYWACKE); gray; intensely weathered; moderately soft; intensely to very intensely fractured; intermittent 6 inch layers of shale. Medium stiff clay seam from 77.2 to 77.5. (continued) 1 22 9 18 25 120 107 Q Q Q Q Q Q Q Q Q Q >< Q Q Q Q Q Q Q Q Q Q Q 2 90 43 3 4 100 24 68 20 5 28 0 6 28 16 7 16 16 Yeh and Associates, Inc• IN Geotechnical • Geological • Construction Services PROJECT NAME Prado Road Bridge Widening PROJECT 216-323 UMBER BORING NUMBER 22Rc-02 REVISION DATE 9/12/2022 SHEET 04 B-63 of 97 N z > W _ O 85 �+ g (7 DESCRIPTION METASEDIMENTARY ROCK (Graywacke) o 5 ` ._ {�pp U E -i Z a p. Cn (A 7 CO a to m 0 -0'�\.. a N ca c Z' 0 a_ 16 o a_ 16 � 3 N 2 U O1 N ._ D 0 fl- C ` f6 07 4 '0 = °) C r °' 0 Remarks C U 53 86 (continued). 0 pulling out rod to confirm depth, 51 87 88 METASEDIMENTARY ROCK CLAYSTONE ; black; intenselyweathered; very soft; intensely sheared. rY Y > 0 plug/table leg Run 8 stuck in sample, extreme disturbance of sample multiple plugs and challenges with fractured rock 8 84 18 89 0 49 90 0 91 Bottom of borehole at 91.0 ft bgs 47 92 93 This Boring Record was developed in accordance with the Caltrans Sod & Rock Logging, Classification, and Presentation Manual (2010) except as noted on the Soil 45 94 or Rock Legend or below. 95 43 96 97 41 98 99 39 100 101 37 102 103 35 104 105 33 106 107 31 108 109 29 110 111 27 112 113 25 114 11 PROJECT NAME Yeh Associates, Inc. Prado Road Bridge Widening PROJECT UMBER and 216-323 Geotechnical • Geological • Construction Services BORING NUMBER 22Rc-02 REVISION DATE 9/12/2022 SHEET B-64 of 97 Rock Core Photos Prado Road Bridge Widening 22RC-01 Run 1 55.3-56.5' 22RC-01 Run 2 56.5-61.5' Project No. 216-323 April 4, 2022 44 ,- N , f 1y 22RC-01 Run 3 61.5-66.5' 22RC-01 Run 4 66.5-71.5' 22RC-01 Run 5 71.5-76.5' /A Page 912 of 1059 B-65 of 97 Rock Core Photos Prado Road Bridge Widening Project No. 216-323 April 4, 2022 22RC-01 Run 6 76.5-81.5' ���``„t4 a �. v^ - -,h .'�:•.r � ,,;t- -� ', 22RC-01 Run 7 81.5-86.5' 22RC-01 Run 8 86.5-91.5' 22RC-01 Run 9 91.5-96.5' 22RC-01 Run 10 96.5-100' Page 913 of 1059 B-66 of 97 Rock Core Photos Prado Road Bridge Widening 22RC-02 Run 1 61.5-66.5' Project No. 216-323 April 4, 2022 COUP.9 ' �} 1 :.3y.� ..yl.- '� �0��. '.� 'Y �('1$r. ' °sue ♦ '( _ _ _-i Ze 44 A,7 22RC-02 Run 2 66.5-71.5' lilt a- iq t t 22RC-02 Run 3 71.5-76.5' 22RC-02 Run 4 76.5-79.0' IN Page 914 of 1059 B-67 of 97 Rock Core Photos Prado Road Bridge Widening 22RC-02 Run 5 79.0-81.5' 22RC-02 Run 6 81.5-84.0' Project No. 216-323 April 4, 2022 VA Page 915 of 1059 B-68 of 97 Rock Core Photos Prado Road Bridge Widening 22RC-02 Run 7 84.0-86.5' 22RC-02 Run 8 86.5-91.0' Project No. 216-323 April 4, 2022 IN Page 916 of 1059 B-69 of 97 1 LU H Q00 O Y C,O N O 7 a2 w p ] w w o[GC w 2r1 oc a Ln H J CL LLI ~ bA - w LLIH wm O �-o f4 Z z o Z M m O w0 w_M UO YM Q -0 O O,1 W.� OY O wW �a ccN a-4 =-4 m J LL ; U O ~ Q C U C Gr V/� w ►+ v C O y as U y bZ/bZ/OL 9IO'�bZOZ l.2ivnNVf bn H3A) J.21V2191I H31. 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VINHOjIIVO fdO'bZOZ-ZZOZ 9VI aNV SOOI £Z£-9 Z 1 A S H3.1 J U v l7 vl C a+ j U U U U J U = U J U j z Q j U � U s t t t � y t � ¢ s 3 3 z � > > > 3 3 3 3 v N 3 z W z Q Y u C g a a > > > > > 3 'a C } w > ¢ � J � � � a a a a o a o v 'a a N � N J U U U U z Q U C � V z Q J J U U -O � N � � � z a _ _ N Sul;salleuol;!ppd � U " � � U U � xapul uolsuedx3 , amen -a � �' o (%);ua;uo� aan;slow uanwl;dp o u ;lug �aa •XeW I$�I/qua) _IJ 0 L L O Ilui -� Ill) ;luau pinbll � � M � � � a (ld) xaPul �3!�!35e1d � � N m ti M N � � I%) Saulj I� n lD W � V�1 � � � `-I N N cN-I C 0 � 0\ Ii) pUeS V ul N c-I M � c-I Q1 ci Ql M ' N Ln I� N m Ln N V V1 ul M W f0 L IiI IaneJ �J LI'1 I� N N n , N m V ul V N aan;slolM N N N N M ' ,n� '�4�!aM;lull dad o o N o � o o, � o, o, � I;7d) .�� '�4�!aM;lull le3ol lD N Lf1 N c-I V m m i l0 N c-I N , N M N N N V Q Q W W J � Q Q � d Q Q � d Q Q d d O N � � m cUc G cUc G � cUc G cUc G N cUc G cUc G � 'a.. � r o 0 0 0 0 �n o o �n o o �n o o � o 0 0 0 L � � ^ O N ll) � N L.f) � N l.f) � � O O O O C G1 G � I= � Z O N N 7 M 7 a •••� N M Lf1 lD I� Ol � ry cN-I N m N � � H � N m coN m m � C .L O N O U N O U N O U N O U O w O w O w O w N O w N O w N O w M O w M O w M O w M O w v� vi In ✓� O Z m °c N m N m N � N � N 7 N 7 N V N � N � N � N � N � N � N � N m m m CO INYeh and Associates, Inc. Geotechnical • Geological • Construction Services Mechnical Sieve Analysis Test Methods: ASTM D6913, D2487, D4718 illProject Name I Prado Road Bridge Project No. 1 216-323 1 Project Manager I J. King Tested By 1 I. Blackburn/R. Atliano Checked By I J. King ITesting Date 1 9/12/2017 SUMMARY OF RESULTS USCS WaterGravel Sample Depth Sand Fines Classification AASHTO Boring No. Content Dio (mm( Dao Imm� Dso Imm( Deo (mm1 Cu Cc No. (ft) (Y.)(%) &Soil Classification NO(%0) Description Well Graded Sand BS-A Creek 0-2 0.0% 46% 53% 1% 0.76 1.96 4.29 6.61 8.70 0.80 with Gravel (SW) brown, moist, subrounded gravel Well -Graded GRAVEL with Sand BS-B Creek 0-2 0.0% 56% 42% 2% 0.74 2.66 5.93 7.90 10.80 1.20 (GW) brown, moist, subrounded gravel Well -Graded SAND BS-C Creek 0 0.0% 43% 55% 2% 0.63 2.11 4.08 5.40 8.60 1.30 with Gravel (SW) brown, moist, subrounded gravel BS-D Creek 0-2 0.0% 2% 83% 15% 0.17 0.30 0.37 - Silty SAND (SM) bank brown, moist Page 919 of 1059 B-72 of 97 ill GRADATION CHARTS Boring No.: BS-A Sample No.: Creek USCS Classification: Well Graded Sand with Gravel (SW) <-------------- Gravel -------------- > 1 <------------------------- Sand ---------------------- > 1 <--------- Fines --------- > 1 3" 2" 1" 3/4" 1/2" 3/8" No.4 No. 10 No.20 No.40 No. 60 No. 100 No. 200 100 90% 80% 70% 60% N a 50 40% 30% 20% 10% 0°/ ��IIIIII■�I�IIIIIq�11�1111■� II�IIl1 ��IIIIII■�I�IIIII��II�IIII■� II�IIII���IIIIII■�I�IIIII��I IIIII■� II�If11����11111■�I�II111��11�1111■� II�IIII���III��1■�I�IIIII��II�IIII■� II�IIIIq��lll11►■�I�IIIIIq�11�1111■� II�IIII���IIIIII� �I�IIIII��II�IIII■� II�I111���111111■ \I�II111��11�1111■� II�IIII���IIIIII■ �1�1��11�1111■� II�II11���111111■ �,Iq_q_II�I111■� 100 10 1 0.1 0.01 Particle Diameter (mm) Boring No.: BS-B Sample No.: Creek USCS Classification: Well -Graded GRAVEL with Sand (GW) 100% 90 80% 70% 60% .S a 50% e 40% 30 20% 10% no/ <-------------- Gravel ---------- > 1 <------------------------ Sand -------------------- > I <--------- Fines --------- > 1 3" 2" 1" 3/4" 1/2" 3/8" No. 4 No. 10 No. 20 No. 40 No. 60 No. 100 No. 200 IIIt11��111111■■I�IIIIIgH11�1111■� II�IIII����IIIIII■■IIIIIII��II�IIII■� II�II11�� �III111■■I�II111��11�1111■� II�IIl1��a111111■■IIII111��11�1111■� II�I111���111111■�IIII111��11�1111■� II�IIIIq��llll�l■�IIIIIIIgH11�1111■� II�I111���11111►�■IIII111��11�1111■� II�IIII���IIIIIIti1�11111��1 l IIIII■� I111111���111111■\��lI111��1I IIIII■� IIIIIII���IIIIII■�Illli�:p�!!!p1111■� o„ 100 IN 10 Particle Diameter0.1 0.01 (mm) Page 920 of 1059 B-73 of 97 ill GRADATION CHARTS Boring No.: BS-C Sample No.: Creek USCS Classification: Well -Graded SAND with Gravel (SW) ��No. 200 00% .0, 80 % 70% rn 60% 0 a 50o/c a 40% 30% 20% 10% 0% 100 1111111 Ism 1 111111NE11111 MM6,10M.".1111M 10 1 Particle Diameter (mm) Boring No.: BS-D Sample No.: Creek bank USCS Classification: Silty SAND IA 0.1 0.01 <-- ----Gravel >I < and >I < Fines >� o 3 12' /8" No.4 No.10 No.20 No.40 No.60 No. 10 No.200 100 /o 90% 80% 70% m 60% c .N a 50% a 40% 30% 20% 10% no/ IIIIq■�IIII�A71 IgHIlIl111■■ IIII■■IIIIIII■■i 111■■IIIIIII■■ IIII■■IIIIIII■■I�I►11■■IIIIIII■■ IIII■■IIIIIII■■Illll�i■■IIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIIIq■�111111■■IIII111l�HIIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIII■■11111■■■111111■■11111■■■ IIII■■IIIIIII■■IIIIIIIHHIiN1111■■ 111■■■IIII IIIIIII■■IIIIIII■■ o 100 10 1 0.1 0.01 Particle Diameter (mm) Page 921 of 1059 B-74 of 97 ill GRADATION CHARTS Boring No.: BS-C Sample No.: Creek USCS Classification: Well -Graded SAND with Gravel (SW) ��No. 200 00% .0, 80 % 70% rn 60% 0 a 50o/c a 40% 30% 20% 10% 0% 100 1111111 Ism 1 111111NE11111 MM6,10M.".1111M 10 1 Particle Diameter (mm) Boring No.: BS-D Sample No.: Creek bank USCS Classification: Silty SAND IA 0.1 0.01 <-- ----Gravel >I < and >I < Fines >� o 3 12' /8" No.4 No.10 No.20 No.40 No.60 No. 10 No.200 100 /o 90% 80% 70% m 60% c .N a 50% a 40% 30% 20% 10% no/ IIIIq■�IIII�A71 IgHIlIl111■■ IIII■■IIIIIII■■i 111■■IIIIIII■■ IIII■■IIIIIII■■I�I►11■■IIIIIII■■ IIII■■IIIIIII■■Illll�i■■IIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIIIq■�111111■■IIII111l�HIIIIIII■■ IIII■■IIIIIII■■IIIIIII■■IIIIIII■■ IIII■■11111■■■111111■■11111■■■ IIII■■IIIIIII■■IIIIIIIHHIiN1111■■ 111■■■IIII IIIIIII■■IIIIIII■■ o 100 10 1 0.1 0.01 Particle Diameter (mm) Page 922 of 1059 B-75 of 97 8C 7C 6C 2C 1C CH or OH 00, CL or OL 4 • it oF O MH or OH ML or OL CL- L 0 0 10 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT, LL Boring Number Sample ID Depth (ft22RC-01 Symbol Test M) Fines LL PL PI Classification 2 10.0 • 12 44 42 19 23 CLAYEY GRAVEL with SAND (GC) 22RC-01 6 30.0 m 29 56 39 20 19 SANDY lean CLAY (CL) 22RC-02 15 20.0 A 76 45 17 28 Lean CLAY with SAND (CL) 22RC-02 19 40.0 * 91 45 22 23 Lean CLAY (CL) 24E-01 1 2.5 O 22 72 44 21 23 Lean CLAY with SAND (CL) 24E-01 3 10.0 0 75 49 17 32 Lean CLAY with SAND (CL) 24E-02 5 2.5 O 14 62 33 16 17 SANDY lean CLAY (CL) 24E-02 7 10.0 A 79 51 20 31 Fat CLAY with SAND (CH) 24E-03 9 2.5 ® 21 54 45 21 24 SANDY lean CLAY (CL) 24E-03 12 15.0 (D 70 40 20 20 Lean CLAY with SAND (CL) Y r ■II Veh and Associates, Inc. L I=A= Geotechnical • Geological • Construction Services ATTERBERG LIMITS PROJECT NAME PROJECT NO. Prado Road Bridge Widening 216-323 REVISION DATE PROJECT MANAGER 10124124 1 J. Kin PREPARED BY CHECKED BY SHEET R. Hooke J. Ross 1 1 of B-76 of 97 � § - \ / 21 �\ of \\ ) 0 �® 2 | } ) 3 / ID J/ ƒ)\} 4 U / { ) } a.0 — §J q &} m ` E E @ � cntun w ,E2 2 � kIDo § § _0 « 4 ! g � .> 2ƒ\ e < § _ / f / § k ± o ~ < U w { » / 2\ # � \Q In T<. , } 0 ) a 2 = \ p � 2 \ n f Q E /)fA e ) °L)( ) ) = 2 q q Page 924 0 1059 reeri•a ..e••.r •• CTM , Yeh • Associates • Brown Lean CLAY w/Sand Expansion _ Pressur Specimen Designation Compactor •• - (psi) •, I �� -- Exudation - (psi) ® •• I • Exudation • . • • I • I • • ®-- Height After Compaction ® • 1 ®-- Expansion Pressure (psf) Stabilometer • 2000 ®® • -- Turns Displacement ��-- Content (%) Wet Density (pcf) DensityMoisture Dry • 1 • ®�� - MMMMMMMMMM MMM 1 11 11 11 �11 11 .11 11 :11 Page 925 of 1059 B-78 of 97 5 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 33.4°, c'= 0.12 ksf - -Total Stress 4 - - Eff. Stress at User Defined Strain / a - Consolidation Stress: 2.1 ksf / Consolidation Stress: 3.6 ksf Consolidation Stress: 5.0 ksf 7 8 9 10 Boring Number 22RC-01 Trial ID A B C Sample Number 5 zO Liquid Limit --- --- --- o Specimen Depth 26.0 ft a Plastic Limit --- --- --- w USCS Classification Sandy lean CLAY (CL): Plastic Index --- --- --- a red brown, moist y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 31.6% 28.1% 26.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 90.4 95.8 98.0 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 99% 100% 100% Cell Pressure, ksf 10.8 12.2 13.7 Z Void Ratio 0.86 0.76 0.72 Back Pressure, ksf 8.6 8.7 8.7 Diameter, in 2.42 2.40 2.40 Consolidation Stress, ksf 2.1 3.6 5.0 Height, in 5.00 4.80 4.68 } a Deviator Stress @ Failure, ksf 2.2 4.0 5.8 2 Axial Strain @ Failure, % o'1F, ksf 3.1 3.0 3.1 5.5 5.1 8.0 Water Content, % 28.1% 26.6% 25.4% w Dry Unit Weight, pcf 95.8 98.0 99.9 rn o'3F, ksf 0.7 1.5 2.2 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.76 0.72 0.69 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) fn � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked by: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 926 of 1059 B-79 of 97 7.0 N Y 6.0 Cl) b 5.0 T b II 4.0 N N .. 3.0 to 0 2.0 M R 1.0 G 00 ri 4.5 b 4.0 T b II 3.5 0 @ 3.0 N 2.5 L N 2.0 c tL 1.5 W 1.0 w 3.0 N Y j 2.5 Q II 2.0 N L 3 H 1.5 d L tl 1.0 d L 0 c 0.5 a� 0.0 c -0 5 0 0 Consolidation Stress: 2.1 ksf Consolidation Stress: 3.6 ksf Consolidation Stress: 5.0 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 A 22RC-01 B 22RC-01 C 22RC-01 4 6 8 10 12 14 Vertical Strain (%) #5 25.0 ft Sandy lean CLAY (CL): red brown, moist #5 25.0 ft #5 25.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 927 of 1059 B-80 of 97 8 7 6 5 N Y c 4 M b 3 i a 2 1 0 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 15.3', c'= 0.52 ksf - -Total Stress - - Eff. Stress at User Defined Strain - Consolidation Stress: 4.3 ksf Consolidation Stress: 5.8 ksf Consolidation Stress: 7.3 ksf 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 p' = (61+a'a)/2, ksf Boring Number 22RC-01 Trial ID A B C Sample Number Run 2 z Liquid Limit --- --- --- o Specimen Depth 57.5 ft a Plastic Limit --- --- --- w USCS Classification CLAYSTONE: brown v Plastic Index --- --- --- a U. Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 19.2% 20.3% 19.9% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 113.6 108.9 109.7 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 107% 100% 100% Cell Pressure, ksf 11.5 13.0 14.4 Z Void Ratio 0.48 0.55 0.54 Back Pressure, ksf 7.2 7.2 7.2 Diameter, in 2.36 2.46 2.49 Consolidation Stress, ksf 4.3 5.8 7.3 Height, in 5.12 4.90 4.75 } a Deviator Stress @ Failure, ksf 3.0 4.3 5.0 2 Axial Strain @ Failure, % 6'1F, ksf 2.0 5.4 3.2 8.1 1.5 10.1 Water Content, % 20.3% 19.9% 19.6% w Dry Unit Weight, pcf 108.9 109.7 110.2 CO) G'3F, ksf 2.3 3.8 5.1 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.55 0.54 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) fn � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 928 of 1059 B-81 of 97 6.0 w N Y 5.0 M b 4.0 b II y 3.0 d L In 2.0 L 0 lE a> 1.0 00 0 2.4 M b 2.2 b II 2.0 0 @ 1.8 N 1.6 L to 1.4 c IL 1.2 ti W 10 Consolidation Stress: 4.3 ksf Consolidation Stress: 5.8 ksf Consolidation Stress: 7.3 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) w 2.5 N Y G 2.0 II 1.5 3 N N ;u 1.0 IL d L ro 0.5 a� j 0.0 C -0.5 0 2 4 6 8 10 12 14 Vertical Strain (%) A 22RC-01 #Run 2 57.5 ft CLAYSTONE: brown B 22RC-01 #Run 2 57.5 ft C 22RC-01 #Run 2 57.5 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 929 of 1059 B-82 of 97 8 7 6 5 N ci Y 4 b 3 i a 2 1 0 - - Effective Stress - - Eff. Stress at Max. Obliquity: W= 33.7', c'= 0.07 ksf - -Total Stress - - Eff. Stress at User Defined Strain / Consolidation Stress: 4.3 ksf 0000 Consolidation Stress: 5.7 ksf / Consolidation Stress: 7.2 ksf 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 P' = (6 t+(T'3)/2, ksf Boring Number 22RC-02 Trial ID A B C Sample Number 20 zO Liquid Limit --- --- --- o Specimen Depth 45.0 ft a Plastic Limit --- --- --- w USCS Classification Lean CLAY (CL): red Plastic Index --- --- --- a brown, moist y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 23.8% 21.5% 20.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 102.0 106.5 108.2 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 98% 100% 100% Cell Pressure, ksf 11.5 13.0 14.4 Z Void Ratio 0.65 0.58 0.56 Back Pressure, ksf 7.2 7.2 7.2 Diameter, in 2.42 2.42 2.44 Consolidation Stress, ksf 4.3 5.7 7.2 Height, in 5.00 4.78 4.65 } a Deviator Stress @ Failure, ksf 3.7 6.2 9.0 2 Axial Strain @ Failure, % o'tF, ksf 3.0 5.0 3.0 8.6 3.3 12.5 Water Content, % 21.5% 20.6% 19.8% w Dry Unit Weight, pcf 106.5 108.2 109.8 rn o'3F, ksf 1.4 2.4 3.5 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.58 0.56 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) fn � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab w Checked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 930 of 1059 B-83 of 97 10.0 Y 9.0 M 8.0 0 7.0 b 6.0 y 5.0 L .. 4.0 to 0 3.0 1° 2.0 N 0 1.0 00 0 ri 4.0 b 3.5 0 II 3.0 0 2.5 N N N L to 2.0 c a 1.5 ti W 10 Consolidation Stress: 4.3 ksf Consolidation Stress: 5.7 ksf Consolidation Stress: 7.2 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) w 4.0 N Y 3.5 3 G 3.0 II 2.5 3 N 2.0 d L a 1.5 d L ro 1.0 a� 0.5 3 0.0 -0.5 ' 0 2 A 22RC-02 B 22RC-02 C 22RC-02 4 6 8 10 12 14 Vertical Strain (%) #20 45.0 ft Lean CLAY (CL): red brown, moist #20 45.0 ft #20 45.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 931 of 1059 B-84 of 97 16 / / - - Effective Stress Consolidation Stress: 5.7 ksf 14 - A Eff. Stress at Max. Obliquity: W= 37°, c'= 0.02 ksf / ._. _ ......... ........ Consolidation Stress: 7.2 ksf - - Total Stress / Consolidation Stress: 8.6 ksf 12 - } - Eff. Stress at User Defined Strain ...................... 10 - ............................... .......................... ..... w Y / N8 ................... .................. ................... ................... ................. ................... ................... ................... ................... 0 b bg ................................................................ u / a / 4 ................................................................................................... / 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 p' _ (6 f+a'3)/2, ksf Boring Number 22RC-02 Trial ID A B C Sample Number Run 3 zO Liquid Limit --- --- --- o Specimen Depth 73.0 ft a Plastic Limit --- --- --- w USCS Classification GRAYWACKE: olive, Plastic Index --- --- --- a highly fractured y Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- co v Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 25.1% 20.7% 20.1% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 106.5 108.0 109.3 Strain Rate, %/min 0.02 0.02 0.02 a Saturation, % 116% 100% 100% Cell Pressure, ksf 12.1 13.7 15.1 Z Void Ratio 0.58 0.56 0.54 Back Pressure, ksf 6.5 6.5 6.5 Diameter, in 2.46 2.50 2.51 Consolidation Stress, ksf 5.7 7.2 8.6 Height, in 5.01 4.79 4.68 } a Deviator Stress @ Failure, ksf 6.2 10.5 18.5 2 D Axial Strain @ Failure, % O'fF, ksf 3.1 8.2 3.1 14.1 6.8 24.6 Water Content, % 20.7% 20.1% 19.6% w Dry Unit Weight, pcf 108.0 109.3 110.2 rn G'3F, ksf 2.1 3.6 6.1 N Saturation, % 100% 100% 100% w Tested By: ND ND ND LLJ Void Ratio 0.56 0.54 0.53 Date Tested: 2/21/22 2/24/22 2/25/22 a Test Method: ASTM 4767 (modified for staged testing) w � Project: Prado Road Bridge Expansion a Tested By: N. Derbidge, Cal Poly Geo-E Lab wChecked By: J. Cravens, Yeh and Associates CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 932 of 1059 B-85 of 97 25.0 N Y M 20.0 0 b 15.0 N N 10.0 N 0 0.0 0 ri 4.5 b 4.0 T 0 II 3.5 0 @ 3.0 N 2.5 L to 2.0 c a 1.5 W 10 w 4.0 N Y 3.5 3 G 3.0 II 2.5 3 N 2.0 d L a 1.5 d L ro 1.0 a� 0.5 3 0.0 Consolidation Stress: 5.7 ksf Consolidation Stress: 7.2 ksf Consolidation Stress: 8.6 ksf 2 4 6 8 10 12 14 Vertical Strain (%) 0 2 4 6 8 10 12 14 Vertical Strain (%) -0.5 ' 0 2 A 22RC-02 B 22RC-02 C 22RC-02 4 6 8 10 12 14 Vertical Strain (%) #Run 3 73.0 ft GRAYWACKE: olive, highly fractured #Run 3 73.0 ft #Run 3 73.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 933 of 1059 B-86 of 97 4 3 0 1 0 - *- - Effective Stress A- - Eff. Stress at Max. Obliquity: V= 16.4', c'= 0.34 ksf - Ar- -Total Stress - *- - Eff. Stress at User Defined Strain / - Consolidation Stress: 0.7 ksf Consolidation Stress: 1.4 ksf Consolidation Stress: 2.8 ksf / 1 2 3 4 5 6 7 8 P' = (a'1+(3 3)/2, ksf Boring Number 24E-01 Trial ID A B C Liquid Limit --- --- --- Sample Number 2 z o Specimen Depth 5.0 ft a Plastic Limit --- --- --- w USCS Classification Lean CLAY w/Sand 2 Plastic Index --- --- --- a (CL): brown, moist (0 Passing #4 (4.75 mm) aa Passing #200 (0.075 mm) --- --- --- L) Estimated Gs 2.70 2.70 2.70 Trial ID A B C Trial ID A B C B-Parameter 0.98 0.98 0.98 Water Content, % 28.1% 30.2% 29.6% t50, minutes N/A N/A N/A Dry Unit Weight, pcf 94.8 92.7 93.7 Strain Rate, %/min 0.02 0.02 0.02 g Saturation, % 97% 100% 100% Cell Pressure, ksf 10.8 11.5 13.0 Z Void Ratio 0.78 0.82 0.80 Back Pressure, ksf 10.1 10.1 10.1 Diameter, in 2.42 2.47 2.49 Consolidation Stress, ksf 0.7 1.4 2.8 Height, in 5.00 4.89 4.77 } a Deviator Stress @ Failure, ksf 1.1 1.6 2.2 2 :D Axial Strain @ Failure, % Cf'1F, ksf 0.8 1.4 1.9 2.4 4.1 4.0 Water Content, % 30.2% 29.6% 28.5% w Dry Unit Weight, pcf 92.7 93.7 95.2 G'3F, ksf 0.3 0.9 1.7 Saturation, % 100% 100% 100% w Tested By: ND ND ND w w Void Ratio 0.82 0.80 0.77 Date Tested: 9/21/24 9/22/24 9/23/24 a Test Method: ASTM 4767 (modified for staged testing) Cn � Prado Road a Tested By: N. Derbidge LuChecked by: R. Hooke CONSOLIDATED UNDRAINED TRIAXIAL TEST Page 934 of 1059 B-87 of 97 ►w. N Y cn 2.0 b b 1.5 u N N L 1.0 in L 0.5 N 0 00 M 5.0 b 4.5 b 4.0 u 3.5 m N 3.0 N 2.5 co 4 2.0 �L a. w 1.5 W 10 y 1.2 Y G 1.0 n L 0.8 U) N N a 0.6 co 0.4 v d 7 0.2 C 00 Consolidation Stress: 0.7 ksf Consolidation Stress: 1.4 ksf Consolidation Stress: 2.8 ksf 0 2 4 6 8 Vertical Strain (%) 0 2 4 6 8 Vertical Strain (%) 0 2 A 24E-01 B 24E-01 C 24E-01 10 12 14 10 12 14 �u 4 6 8 10 12 14 Vertical Strain (%) #2 5.0 ft Lean CLAY (CL): brown, moist #2 5.0 ft #2 5.0 ft CONSOLIDATED UNDRAINED TRIAXIAL TEST Page 935 of 1059 B-88 of 97 40 35 30 w Y 25 M b b 20 N N N i .+ y 15 O R y 10 G 0 61 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 22RC-01 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 3 ZO a Sample Depth: 64.0 ft a 44 (4.75mm) --- Plastic Limit --- USCS Classification: GRAYWACKE: bluish gray v 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.75 S. from T,, ksf --- Water Content, % 9.2% N W Dry Unit Weight, pcf 127.3 v 4200 (0.075mm) --- S. from PP, ksf --- wSaturation, % 73% 0 Void Ratio 0.35 Maximum Deviator Stress, ksf 35.2 a Diameter, in 2.41 Undrained Shear Strength, ksf 17.6 Height, in 3.89 } Axial Strain at Failure, % 9.9 Strain Rate, %/min 1.0 2 Cell Pressure, ksf 7.9 p Tested By: ND Date Tested: 3/4/22 N U) W ~ W Q W a- Test Method: ASTM 2850 aProject: Prado Road Bridge Expansion co The specimen's length to diameter ratio was less than 2 Tested By: N. Derbidge, Cal Poly Geo-E Lab W Checked By: J. Cravens, Yeh and Associates UNCONSOLIDATED UNDRAINED TRIAXIAL TEST REPORT Page 936 of 1059 B-89 of 97 2.5 2.0 0.0 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 24E-03 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- W Sample Number: 10 Oz a Sample Depth: 5.0 ft a 44 (4.75mm) --- Plastic Limit --- a USCS Classification: Lean CLAY (CL): dark brown, moist 0 416 (1.18mm) --- Plasticity Index --- LL a 430 (0.6mm) --- *100 (0.150mm) --- Estimated Gs 2.75 S. from T, ksf --- Water Content, % 30.9% w Dry Unit Weight, pcf 87.3 v *200 (0.075mm) --- S from PP, ksf --- wSaturation, % 88% 0- Void Ratio 0.97 Maximum Deviator Stress, ksf 2.2 a Diameter, in 2.42 Undrained Shear Strength, ksf 1.1 Height, in 5.00 Axial Strain at Failure, % Strain Rate, %/min 15.0 1.0 Q Cell Pressure, ksf 0.7 Tested By: ND co Date Tested: 9/18/24 w w C9 W a Test Method: ASTM 2850 Prado Road Tested By: N. Derbidge Checked By: R. Hooke w UNCONSOLIDATED UNDRAINED TRIAXIAL TEST Page 937 of 1059 B-90 of 97 60.0 50.0 w 40.0 y Y b b 30.0 N N N i J o 20.0 5 N 10.0 0.0 Axial Strain, % Confining Stress: 0.0 ksf • Interpreted Point of Failure 10 12 14 16 o Boring Number: 22RC-01 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 5 ZO a Sample Depth: 73.5 ft a 44 (4.75mm) --- Plastic Limit --- USCS Classification: GRAYWACKE: olive 0 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.90 S from T,, ksf --- Water Content, % 12.3% N w Dry Unit Weight, pcf 124.0 v 4200 (0.075mm) --- S from PP, ksf --- Saturation, % 78% w 0 Void Ratio 0.46 Maximum Deviator Stress, ksf 54.1 W Diameter, in 2.33 Undrained Shear Strength, ksf 27.0 Height, in 2.87 } IY Axial Strain at Failure, % Strain Rate, %/min 0.9 0.1 2 Cell Pressure, ksf 0.0 m Tested By: ND ' Date Tested: 3/11/22 Cn w =� n� Q w ,• , ar: Test Method: ASTM 2850 Cn Project: Prado Road Bridge Expansion < Y Tested By: N. Derbidge, Cal Poly Geo-E Lab �>r Checked By: J. Cravens, Yeh and Associates �t W UNCONFINED COMPRESSION TEST REPORT Page 938 of 1059 B-91 of 97 3.5 3.0 2.5 w y Y n 2.0 b b N N 1.5 N i r+ O 1.0 N G 0.5 0.0 0 2 4 6 8 10 12 14 16 Axial Strain, % o Boring Number: 22RC-02 Sieve Size % Passing Other Parameters 3/8-in. (9.5mm) --- Liquid Limit --- w Sample Number: Run 2 ZO a Sample Depth: 67.0 ft a 44 (4.75mm) --- Plastic Limit --- a USCS Classification: GRAYWACKE: olive 0 416 (1.18mm) --- Plasticity Index --- w N Q 430 (0.6mm) --- #100 (0.150mm) --- Estimated Gs 2.90 S. from Tv, ksf --- Water Content, % 17.5% N w Dry Unit Weight, pcf 120.2 v 4200 (0.075mm) --- S. from PP, ksf --- wSaturation, % 100% 0 Void Ratio 0.51 Maximum Deviator Stress, ksf 3.1 a Diameter, in 2.30 Undrained Shear Strength, ksf 1.6 Height, in 5.02 } 0: Axial Strain at Failure, % Strain Rate, %/min 1.5 1.0 2 Cell Pressure, ksf 0.0 p Tested By: ND Date Tested: 3/4/22 Cn U) W W a w Test Method: ASTM 2850 aProject: Prado Road Bridge Expansion U Tested By: N. Derbidge, Cal Poly Geo-E Lab Checked By: J. Cravens, Yeh and Associates W d' UNCONFINED COMPRESSION TEST REPORT Page 939 of 1059 B-92 of 97 Unconfined Uniaxial Compressive Strength Test of Intact Rock Cores ASTM D7012 - 1.5.1 Method C: Uniaxial Compressive Strength of Intact Rock Cores Job No.: 216-323 Project: Prado Road Bridge Expansion F— V W Client: Yeh and Assoc., Inc. _ O Date: 3/6/2022 a Test Method: ASTM D7012 (1.5.3 Method C: Uniaxial Compressive Strength of Intact Rock Core Specimens) 0 Boring Number: 22RC-01 Sample ID: Run 4 I CL Sample Depth: 70.5-71.0 ft N Classification: I GRAYWACKE Moisture Condition: As Received two E A H Moisture Content: N/A Unit Weight (pcf): 145.1 CL 0 Dry Unit Weight (pcf): N/A a Length/Diameter : 2.22 Comp. Strength (psi): 390 Specimen Length:Diameter within 'desireable' range of 2.0:1 to 2.5:1 per ASTM D7012 section 8.1.1 Moisture contents not measured Boring Number: 22RC-01 Sample ID: Run 9 CL Sample Depth: 93.0-94.0 ft M N Classification: I GRAYWACKE C Moisture Condition: As Received two N Moisture Content: N/A Unit Weight (pcf): 164.5 CL I Dry Unit Weight (pcf): N/A Length/Diameter : 2.42 Z n R f� IC _�! 22. f, C 4 Comp. Strength (psi): 6,130 s t�' !-� y.—1>�'-- Specimen Length:Diameter within 'desireable' range of 2.0:1 to 2.5:1 per ASTM D7012 section 8.1.1 Moisture contents not measured Page 940 of 1059 B-93 of 97 4 . u Z ---i � J p p O W U U 'E W 00 co i �o)U U 3 CD E OO� p D a) W U (n 0 , c m p J rn�p ii Q p O U N N e p O fn J m a) U� i O p m L fB Q O ir f6 a) (� O a> -p N L 1059 t 3 (38S/4) *a _« now 3mA@ mBW! m _ a� }) «t \� } z \ w a e § q w _ 2 < ' c ))§ \§ r )\7 CD > , ) §)§ /$§ , 02/ \LL/ . a) \� ` k _0co $ ° @E « k co m m § \ G m / ° 0 \\ co LL k ` / / \ \j \ e $ U§ t io @ 0 m ® § 22 c \ coco () k co \ N ^ o (I \ d r-f & \ ƒ // / R % ^ \\ 2 4 .= 2 $\ � )s-0 0 #{. a)¢c Q° ■` �) - /t /col, k ko E \ . E\ ' $ \\ § (@ wR G) b{ _ § 2/ Co»$ §Q » S\ co�\/ § Ip «® §± I) to U- �/ \\ / a)\ , s ' \\\ \� �\ m a) £Q» 2 )k) j\ \co 2 0 o§ k7 e ° ° ° ` c)M k7 «g}pae +ƒ* 12_ §a Page 942 0 1 059 Line 1 Station 165 ft 1 D Shear -Wave Velocity Profile Velocity (ft./sec) N N w w a A ca ai 0/ Of U O U O U O U O U p (71 Q (JI O O C. O O 8 O O 08 CO S 00 N U O 1,800 ft/sc Velocity Layer at 25.4 ft Interpreted as Bedrock Surface o`a b � o t� to b i— a T m x ii O d^ • C .o j 's �- i �;Yj C N 3 `0 - O a I I ZA A � =Z W O fh ti N U 8 O N - O Based on SurfSeis MASW Processing and Modeling using 4-Layer Vs Model Figure 3 ADVANCEB E�CVWC. Line 1 Station 415 ft 1 D Shear -Wave Velocity Profile Velocity (ft./sec) N N fJ tJ A A VI (.71 Ol Ol VI O (T O (T O V1 O VI O 0 C (JI O C. O O O O O O O C. O O C. O O O O C. O O O O O O O C. rn �i f^ 3 L'+ N '[I C R N w �fl T 7 � m V m y �sr 4 1,780 ft/sc Velocity Layer at 34"3 ft Interpreted as Bedrock Surface M o E " n a y O N Based on SurfSeis MASW Processing and Modeling using 4-Layer Vs Model Figure 4 ADVANCE®d E G` QW. 05 - SLO - 101 — PM 26.5/27.3 05-1H640 — 0516000105 PPNO-2831 20.XX.075.600 STIP RIP 20.XX.400.100 Local Funds August 2026 Draft Supplemental Project Report For Project Approval On Route US 101 Between 0.3 mile south of Prado Road And 0.2 mile south of Madonna Road Overcrossi I have reviewed the right-of-way information contained in this report and the right-of- way data sheet attached hereto, and find the data to be complete, current and accurate: David Adams, Deputy District Director, Right of Way APPROVAL RECOMMENDED: Genaro Diaz, Project Manager PROJECT APPROVED: Scott Eades, District Director Date Page 945 of 1059 05-SLO-101-PM 26.5/27.3 Vicinity Map Page 946 of 1059 05-SLO-101-PM 26.5/27.3 This project report has been prepared under the direction of the following registered civil engineer. The registered civil engineer attests to the technical information contained herein and the engineering data upon which recommendations, conclusions, and decisions are based. REGISTERED CIVIL ENGINEER DATE PFtOFESSIpNq,\ �O F P ti iz Dace Morgan 9 12/31/2027 sT r CIVIL \F OF C Page 947 of 1059 05-SLO-101-PM 26.5/27.3 Table of Contents 1. INTRODUCTION 1 2. RECOMMENDATION l 3. BACKGROUND 1 4. PURPOSE AND NEED 3 5. ALTERNATIVES 3 6. CONSIDERATIONS REQUIRING DISCUSSION 4 7. OTHER CONSIDERATIONS AS APPROPRIATE 4 8. FUNDING, PROGRAMMING AND ESTIMATE 5 9. DELIVERY SCHEDULE 6 10. RISKS 7 11. EXTERNAL AGENCY COORDINATION 7 12. PROJECT REVIEWS 7 13. PROJECT PERSONNEL 7 14. ATTACHMENTS (Number of Pages) Error! Bookmark not defined. Page 948 of 1059 Page 949 of 1059 05-SLO-101-PM 26.5/27.3 1. INTRODUCTION Project Description The US101 and Prado Road Interchange Project Report (PR) and Environmental Document were approved in October 2024. The purpose of this Supplemental Project Report is to document changes to the preferred alternative, approved in October 2024. The scope changes include reducing the number of through lanes of the overcrossing from 4-lanes to 2-lanes, replacing the sidewalk and Class IV bike path on both sides of Prado Road with a Class I mixed -use path on the south side of Prado Road and a sidewalk on the north side of Prado Road, reducing the overall length of bridge structures from approximately 2,550 feet to approximately 1,250 feet, the addition of retaining walls at the beginning and end of the bridges, and the addition of a eight sided retaining wall structure at the northbound ramp terminal intersection. Project Limits 05-SLO-101, PM 26.5/27.3 Current Cost Estimate FY 2026: Escalated Cost Estimate FY 2029: Capital Outlay Support $9,248,000 $10,705,000 Capital Outlay Construction $103,700,000 $124,210,000 Capital Outlay Right -of -Way $4,996,251 $5,783,785 Funding Source State Transportation Improvement Program (STIP), Regional Improvement Program (RIP) and Local Funds Funding Year 2027/2028 Type of Facility Local Interchange Number of Structures 4 bridges, 9 retaining walls Environmental Determination or Document NEPA CE/CEQA IS-MND Legal Description In San Luis Obispo County, on Route 101 between 0.3 mile south of Prado Road and 0.2 mile south of Madonna Road Overcrossing Project Development Category 3 2. RECOMMENDATION It is recommended approval of this Supplemental Project Report and the project proceed to the PS&E phase. 3. BACKGROUND The US 101/Prado Road Interchange Project Report (PR) and Environmental Document were approved in October of 2024. A Value Analysis (VA) for the project Page 950 of 1059 05-SLO-101-PM 26.5/27.3 was completed in Spring of 2023. The VA identified the following items to be considered: 1. Reduce the maximum speed on Prado Road to 35 mph (this was implemented as part of the PA&ED and Caltrans approved the Design Standard Decision Document (DSDD) for this revision) 2. Reduce lane and shoulder widths where practical 3. Use CIDH columns in lieu of driven piles and pile caps 4. Use longer spans and fewer columns with precast I -girders in lieu of CIP griders 5. Leave existing sewer main on current Elks Lane alignment in lieu of relocation (this was rejected by project stakeholders and was not implemented) 6. Utilize recycled and/or reclaimed materials in project The decision was made to implement the appropriate and applicable recommendations during the PS&E phase of the project and not incorporate them into the PA&ED phase. As a result of the VA and follow up traffic counts and analysis, preliminary geotechnical analysis, and more detailed hydraulic analysis, the following revisions have been incorporated into the project: 1. Prado Road Overcrossing width is reduced from 4-lanes to 2-lanes 2. Bridge span lengths have been increased from 100 feet to 150 feet 3. Overall length of bridges has been reduced from approximately 2,550 feet to approximately 1,250 feet 4. Retaining walls have been added at the beginning and ends of the overcrossing structures and northbound ramp structures 5. The northbound ramp terminal intersection is encompassed by an eight -sided retaining wall 6. A Class I multi -use path has been incorporated along the south side of Prado Road within the project limits 7. A 6 foot wide sidewalk is maintained along the north side of Prado Road within the project limits 8. Prado Road has 12 foot travel lanes and 4 foot shoulders within Caltrans right of way. At the ramp intersection the eastbound Prado left turn lane to the northbound US 101 on -ramp is proposed to be 11 feet. 2 Page 951 of 1059 05-SLO-101-PM 26.5/27.3 4. PURPOSE AND NEED No change (See approved PR) 5. ALTERNATIVES The approved 2024 Project Report selected Alternative A3 as the preferred alternative. The alternative consists of a Type L-1 tight diamond interchange. The alternative is a partial interchange with north bound ramps and an auxiliary lane from the north bound on -ramp to Madonna Road off -ramp. The interchange type will remain as proposed in the Project Report. The revisions focus on the span configuration of the bridge structures, the implementation of retaining walls where feasible, and the reconfiguration of the Prado Road cross section. Design Charrettes were conducted with the City of San Luis Obispo and Caltrans staff to explore alternatives to Alternative A3 that would result in a lower overall construction cost. A performance based design approach was incorporated with a focus on not impacting US 101 mainline operations, reducing crash severity on Prado Road, Mainline Ramp merge and diverge, pedestrian level of stress, emergency vehicle response, and safety queueing issues. With the performance criteria defined, a traffic sensitivity analysis was conducted with traffic counts obtained in May 2025. The traffic sensitivity analysis compared a four -lane corridor with a two-lane corridor and roundabout and signal intersection controls. Reducing the entire Prado corridor to two lanes resulted in unacceptable delays and congestion that spilled back to Higuera (PM peak) to the east and the Froom Ranch roundabout (AM peak) to the west. Through iterations, it was determined that a four - lane section from the Higuera/Prado intersection to the NB ramp terminal intersection and then a two-lane section from the NB ramp terminal to the Froom Ranch/Dalidio Drive roundabout would result in acceptable operations during peak and non -peak hours. The Prado corridor would experience some delays and congestion in the peak hours starting in 2045, assuming full land use build out of the City's current general plan. As part of the design charrette process, the PDT proposed replacing the combination sidewalk and Class IV protected bike paths on both sides of the corridor with a multi- use bidirectional pathway on the south side of Prado and a 6-foot-wide sidewalk on the north side of Prado Road. This cross section for bikes and pedestrians closely matches the facilities throughout the San Luis Ranch development. On Nov 4, 2025, the City Council approved the reconfiguration of the Prado Road corridor from Higuera Street to Froom Ranch/Dalidio Drive roundabout. These changes implemented during the PS&E phase results in an interchange configuration that substantially meets the configuration of Alternative A3 from the 2024 PR. Page 952 of 1059 05-SLO-101-PM 26.5/27.3 6. CONSIDERATIONS REQUIRING DISCUSSION 6A. Hazardous Waste No change (See approved PR) 6B. Value Analysis A Value Analysis was completed in Spring of 2023. The recommendations from the VA have all been incorporated into the updated project, with the exception of not relocating the City owned sewer main. The sewer main will be relocated within the new alignment of Elks Lane. 6C. Resource Conservation No change (See approved PR) 6D. Right -of -Way Issues Consistent with the approved PR, new right of way will be required for the project (See approved PR). This project will be undergrounding overhead electric and communication utilities, relocating City owned water and sewer facilities and relocating two Phillips 66 oil lines. Potholing has been performed for utility location verification. 6E. Environmental Compliance In 2023, an Initial Study with Mitigated Negative Declaration (IS/MND) was prepared and approved for the US 101/Prado Road Interchange Project. An environmental revalidation is currently being processed and will be completed by March 2027. The CEQA IS/MND was approved August 30, 2023 and the NEPA CE was approved December 12, 2023. 6F. Air Quality Conformity No change (See approved PR) 6G. Title VI Considerations The proposed change to Class IV facility is now provided through the implementation of a Class I multi -use path located on the south side of Prado Road. 7. OTHER CONSIDERATIONS AS APPROPRIATE Traffic A Traffic Operations Analysis Report (TOAR) was completed in 2019 using the Page 953 of 1059 05-SLO-101-PM 26.5/27.3 City's Land Use and Circulation Element (LUCE) model and traffic counts from 2014. The 2019 TOAR had opening day of 2025 and the design year as 2045. An amended TOAR was produced in 2022. This version had a design year of 2050. The traffic demand model was not updated for the 2022 TOAR. The updated traffic forecasting was determined by applying a straight 1 % growth rate per year for a total of 5% grow. No new or updated City land uses were incorporated. New traffic counts in 2025 at 26 intersections (the same intersections as were used in the original 2019 TOAR) were obtained. A comparison of the original TOAR 2025 counts and the actual counts completed in 2025 showed that the actual counts were generally lower than those forecasted in the original and amended TOAR document. An updated City traffic demand model update was developed in 2025/2026. The updated model utilized updated traffic counts and land uses. The traffic sensitivity analysis and the supplemental traffic operations memorandum utilized the City updated traffic demand model from 2025/2026. A review and comparison of the forecast volumes at all 26 counted intersections, which included the adjacent LOVR and Madonna interchanges, from the amended 2022 TOAR and the updated City model for the no -build, 4-lane and 2-lane Prado overcrossing. Based on this review and comparison, the updated traffic demand model results in lower traffic volumes for all scenarios, except at the LOVR Southbound off ramp, Madonna Northbound on ramp, and Madonna Road overcrossing. These three locations were discussed at a PDT meeting on XX and was concluded that the increase in volumes would not degrade operations at those locations. Complete Streets The project will enhance bicycle and pedestrian facilities along the Prado Road corridor from Higuera to Froom Ranch/Dalidio Drive roundabout. Alternative A3 included sidewalks and Class IV bicycle facilities on both sides of Prado Road. The reconfigured alternative includes a separated Class I mixed use path on the south side and a sidewalk on the north side within the interchange area. The proposed design was shared with the City of San Luis Obispo Active Transportation Committee (ATC) on May 20, 2026 and at community meeting on March 11, 2026. The proposed improvements and reconfiguration were presented to the San Luis Obispo City Council on November 4, 2025 and they approved the reconfiguration of the Prado Road corridor. 8. FUNDING, PROGRAMMING AND ESTIMATE Funding No Change (See approved PR). It has been determined that this project is eligible for Federal -aid funding. Page 954 of 1059 05-SLO-101-PM 26.5/27.3 Programming Fund Source Fiscal Year Estimate Local/RIP Prior 25/26 26/27 27/28 1 28/29 1 29/30 30/31 1 Future Total Component IF In Thousands ($1,000) PA&ED Support 1,500 1,500 PS&E Support 3,000 2,000 2,500 1,500 9,000 Right -of -Way 300 80 80 460 Support Construction 1,000 2,200 2,200 5,400 Support Right -of -Way 2,000 3,400 1 5,400 Construction 7,700 50,000 46,000 103,700 Total 1,500 3,300 2,080 4,580 13,600 52,200 48,200 125,460 Cost Item Current (25/26) In Thousands Escalated (28/29) In Thousands Construction $82,960 $99,400 Supplemental Work $0 $0 Contingencies (25%) $20,740 $24,800 Total $103,700 $124,200 9. DELIVERY SCHEDULE Project Milestones Milestone Date (Month/Day/Year) Milestone Designation (Target/Actual) PROGRAM PROJECT M015 04/27/2018 Actual BEGIN ENVIRONMENTAL M020 05/11/2018 Actual PA & ED M200 10/04/2024 Actual PROJECT PS&E M380 10/24/2028 Target RIGHT OF WAY CERTIFICATION M410 09/24/2028 Target READY TO LIST M460 02/19/2029 Target AWARD M495 04/15/2029 Target APPROVE CONTRACT M500 05/15/2029 Target CONTRACT ACCEPTANCE M600 12/31/2031 Target END PROJECT EXPENDITURES M800 6/l/2032 Target FINAL PROJECT CLOSEOUT M900 12/1/2032 Target Page 955 of 1059 05-SLO-101-PM 26.5/27.3 10. RISKS No Change (See approved PR). 11. EXTERNAL AGENCY COORDINATION No Change (See approved PR). 12. PROJECT REVIEWS District Maintenance Berkeley Lindt Date Headquarters Project Delivery Coordinator Robert Navarro Date Project Manager Genaro Diaz Date 13. PROJECT PERSONNEL Name Functional Unit Organization Phone Genaro Diaz PPM Caltrans (805) 721-2365 Bing Yu Traffic Safety Caltrans (805) 903-3596 Saygunn Low OSFP&SLA Caltrans (916) 639-5902 Tony Nedwick SHH Caltrans (916) 227-8852 David Smotherman RW Engineering Caltrans (805) 549-3117 Robert Davis RW Engineering Caltrans (805) 556-2240 Colton Christensen RW Engineering Caltrans (805) 779-0636 Kevin Thorne RW Engineering Caltrans (805)779-0647 Dylan Robertson Design Oversight Caltrans (805) 503-3754 Adrian Foster RW Engineering Caltrans (805)305-7876 Dianna Beck Environmental Caltrans (805) 459-9406 Daniel Johnson Environmental Caltrans (805) 903-3521 David Karp RW Engineering Caltrans (805) 305-7932 Nikki Bloom Landscape Engineering Caltrans (805) 748-9800 Scott Dowlan Landscape Engineering Caltrans (805) 540-4407 Corby Kilmer Landscape Engineering Caltrans (805) 721-2805 Berkeley Lindt Maintenance Engineering Caltrans (805) 549-3315 Tyler Laing Maintenance Engineering Caltrans (805) 858-8191 Ryan Blanc Stormwater Engineering Caltrans (805) 458-5838 Dario Moreno Transportation Engineering Caltrans (805) 835-6570 Kamal Humagain Transportation Engineering Caltrans (805) 872-5658 Jerrod Lessel Travel Forecast Caltrans (805) 393-5805 Page 956 of 1059 05-SLO-101-PM 26.5/27.3 Abraham Almaw DES Engineering Caltrans (916) 227-8699 Amy Norris Design Liaison Caltrans (805) 503-3619 Robert Navarro Project Delivery Caltrans (530) 949-8730 David Gallego Traffic Engineering Caltrans (805) 903-3457 Chirag Akbari Traffic Engineering Caltrans (805) 903-3612 Juan Moreno Drainage Engineering Caltrans (805) 478-9939 Matt Horn Project Manager City of San Luis Obispo (805) 423-0200 Brian Nelson City Engineer City of San Luis Obispo (805) 781-7113 Luke Schwartz Traffic Signal Manager City of San Luis Obispo (805) 781-7190 Mark Reno Principal -in -Charge Consor (916) 368-9181 Brent Lemon Project Manager Consor (916) 799-4910 Dace Morgan Deputy Project Manager Consor (805) 503-8524 Brent Harrison Roadway PE Consor (925) 430-1666 Scott McCauley Bridge PE Consor (916) 368-9181 Jim Damkowitch Traffic DKS (916) 368-2000 Brian Ray Quality Control Sunrise Transportation (503) 539-1808 Lincoln James Grant Funding AECOM (858) 866-6095 Maxim D Nasab Bridge Architecture Apexx (707) 688-0246 Chris Sewell Hydraulics, Stormwater, Drainage HDR (925) 465-2743 Colby Boggs Environmental/Permitting Rincon (805) 547-0900 Mary Verdin Public Involvement Verdin Marketing (805) 235-0507 Clayton Bradshaw Survey Wallace Group (805) 544-4011 Judd King Geotechnical Yeh & Associates (805) 481-9590 Page 957 of 1059 Page 958 of 1059 <<[L W Cl Z _4-0 V0) u W F CQ U Zv i 0. — O� Q •—i P 0 co .N N O Q � � N J co 1..` a (n � i Z .O W *' � Z O V m c� a E 0 LL u m 0 Q c O L CD a s Z 06 M 0 ui D c O ►3 a c� a E 0 LL V m 0 Q O O (1) �I fa ix a c� a E 0 LL V m 0 Q Q 41 CL _ O U a a w a cai =o U CL I LU ZO Q J a (n 41 Q 4) Z u O U O F a O W a cai W U C �� H 0 ZO Q J a W (n z O F— a O W Q t In 41 CL 0 _ 0 U a i a w a cai =o U CL I LU Z_0 03 Q J a (n z O z Q �c w 0 w m z O F— a O W Q 1 L 41 CL 0 _ 0 U a i i a w a cai =o U CL I LU Zo o Q J a (n Z O Z Q W 0 W m 0 z O F— a O W Q 41 Q 4) u _ O U a i a w a cai =o U CL I LU Zo o Q J a (n m W'} n o Q 1 rn L(L) �c cu V C Odyf qH O Z O 'sAn m LI It nT Q' rn L(L) Oc cu V C Odyf 41 CL a) u r_ 0 U a i i a w a cai =o U CL I LU Zo o Q J a (n W J H 41 CL 0 _ 0 U a a w a cai = o U IX_� H � ZO m O '3 Q J a (n Z O F- a O w J F- 41 CL _ 0 U a a w U a cai = o U IX_� H � Z_O O 3 Q J a (n O�3 oast o4��E�o SAl� 41 CL _ 0 U a a w U a cai = o U IX_� H � Z_O O 3 Q J a (n Z O Z W 0 W m 0 Z O F- a O w J F- oast o4��E�o SAl� 41 CL _ 0 U a a w U a cai = o U IX_� H � Z_O O 3 Q J a (n Tq O 2 D Z O z O F— a O w J F- 41 CL _ 0 U a a w U a cai = o U IX_� H � Z_O O 3 Q J a (n z O F— a O w J F- 'sAn 41 CL _ 0 U a E a w U a cai = o U IX_� H � Z_O O 3 Q J a (n Z O F— a O W J F- m LL 4- n o Q `t rn L(L) �c cu V C Odyf 41 CL _ 0 U a a w U a cai = o U IX_� H � Z_O O 3 Q J a (n oasf SAl� z O O LU VI r' L O Q (� r / u 0 U � 5 a Zw a cai W UQ LLI o Q J a (n a Z c/ LU 0 O 'sAn 41 CL 0 _ 0 U a i a w Z Q QU = O U IX_� H � Z_O O 3 Q J a (n 11w Z O Z F- W 0 W a Z O CL O Z LU 0 O Rw 41 Q 4) u r_ O U a i i a w Z Q QU = O U IX_� H � Z_O O 3 Q J a (n 41 Q 4) u r_ O U a i i a w Z Q QU = O U IX_� H � Z_O O 3 Q J a (n ► , jp i IIII��� ' NIII� � IIIN IIIN I i 2 0 Z vq 0 ,2 V I D Z 0 z 0 0 Z GC w O 'sAn ate+ Q O u r_ O U a a w U a cai =o U IX_� H � Z_O O 3 Q J a (n z 0 F— CL 0 Z GC W 0 G m X- I nT Q'bo rn L(L) O0) c10 V C Odyf 41 Q 4) V i O U a a w Z Q QU =o U IX_� H � OO Q J a (n Page 982 of 1059 Preliminary Value Analysis Study Report Prado Creek Bridge VMS No. 3530-001 July 2026 Prepared by Value Management Strategies, Inc. WALLACE GROUP VMS Page 983 of 1059 VMS Value Management Strategies, Inc. Date: July 1, 2026 To: Jorge Aguilar, Wallace Group Project Manager Subject: Preliminary VA Study Report Prado Creek Bridge Dear Mr. Aguilar, Value Management Strategies, Inc. is pleased to submit this Preliminary VA Study Report for the referenced project. This report summarizes the results and events of the hybrid in -person and virtual study conducted March 30-31 and April 2, 2026, facilitated via the Microsoft Teams virtual meeting platform. DECISION -MAKERS PLEASE NOTE: An Implementation Meeting will be scheduled at a future date. You will be asked to accept or reject each VA alternative included in this report. In addition, you will be asked to agree or disagree with the cost savings and performance attribute ratings the VA team applied to each accepted VA alternative. Acceptance of alternatives denotes intent to implement, based on current information, in the given project development phase. It is recognized that future conditions may change this disposition. The validation of disposition, the cost changes, and performance changes for the alternative is required by the Caltrans VA methodology (at the City's discretion) to ensure that the project decision -makers agree with the study results. Furthermore, these validated results become the basis for the VA Program reportables. The VA process is complete when the implementation decisions for every VA alternative have been received from the City Project Manager and documented in the Final VA Study Report. The Assess Alternatives and Resolve Alternatives activities provide the VA team, the PM, and the City of San Luis Obispo assurance that the alternatives are properly evaluated and the implementation decisions are based on the merit of each concept. This process helps to eliminate inaccurate alternatives and legitimizes the results of the study and the VA Program. Please complete your review of the VA alternatives and provide your written comments on the VA Alternative Project Stakeholder Implementation Action Recommendation forms. We will target one week prior to the Implementation Meeting to receive these forms; please send them to eric.trimble@vms-inc.com. CORPORATE OFFICE: 350 W. Fifth Avenue, Suite 330 1 Escondido, CA 92025 Tel: 760 7415518 1 Fax: 760 7415617 1 www.vms-inc.com MAILING ADDRESS: PMB #263 15309 McPherson Blvd, Suite 105 Fort Worth, TX 76123 OFFICE LOCATIONS: AZ I CA I KY I MI I NC I ND I NE I NH I NJ I OR I TX I VA I WA Page 984 of 1059 V M S T, During the Implementation Meeting, we will review the individual Implementation Action Recommendation Form responses, develop a consensus for each VA alternative, document the responses to each alternative, and conclude decisions related to implementation. After that meeting, we will integrate the results into the Final VA Study Report. It was a pleasure working with the Wallace Group team and the City of San Luis Obispo on this project, and I look forward to the next one. If you have any questions or comments concerning this preliminary report, please do not hesitate to contact me at (206) 679-8029 or email eric.trimble@vms-inc.com. Sincerely, Value Management Strategies, Inc. Eric Trimble, CVS, MBA, PMP VP (Value Engineering) VA Study Team Leader Page 1 2 Page 985 of 1059 TABLE OF CONTENTS VA STUDY SUMMARY REPORT..................1 Project Summary Project Purpose and Need VA Study Timing VA Study Objectives Key Project Issues Evaluation of Baseline Concept • Performance Attributes VA Alternatives VA Study Results VA Team VA ALTERNATIVES....................................9 VA Strategies VA Alternative Summary Tables • VA Alternatives • Recommended VA Strategies Other Considerations Summary of Performance Improvements VA Alternative Documentation PROJECT INFORMATION .........................37 Background Project Description Project Design Exceptions Information Provided to the VA Team Project Drawings Project Cost Information PROJECT ANALYSIS.................................39 Summary of Analysis Key Project Factors • Project Issues • Site Visit Observations Cost Model Function Analysis PRELIMINARY PROJECT ANALYSIS (continued) Value Metrics • Define Performance Requirements • Define Performance Attributes and Scales • Prioritize Performance Attributes • Measure Performance of Baseline Concept • Measure Performance of VA Alternatives • Define VA Strategies • Compare Performance — Baseline Design and Recommended VA Strategies • Rating Rationale for Recommended VA Strategies • Compare Value • Value Matrix — Baseline Concept and VA Recommended Strategies IDEA EVALUATION..................................52 Performance Attributes Evaluation Process Idea Summary Idea Summary List Detailed Idea Evaluation VA PROCESS............................................56 Pre -Study VA Study VA Report Caltrans VA Study Activity Chart VA Study Agenda VA Study Meeting Attendees Prado Creek Bridge Table of Contents Page 986 of 1059 VA STUDY SUMMARY REPORT PRELIMINARY FINDINGS Page 987 of 1059 VA Study Summary Report - Preliminary Findings Prado Creek Bridge eN`^� - — — F ' A Value Analysis (VA) study, sponsored by the City of San Luis Obispo in general conformance to California Department of Transportation (Caltrans) VA study methodology and facilitated by Value Management Strategies, Inc. (VMS), was conducted for the Prado Creek Bridge project located in the City of San Luis Obispo, California. The workshop was facilitated as a hybrid in -person and virtual study March 30-31 and April 2, 2026, using Microsoft Teams. This VA Study Summary Report — Preliminary Findings provides an overview of the project, key findings, and the alternatives developed by the VA team. PROJECT SUMMARY The City of San Luis Obispo (City), through the Federal Highway Administration (FHWA) and the Highway Bridge Program (HBP) as administered by the California Department of Transportation (Caltrans), is proposing to replace Bridge No. 49C-0107 on Prado Road over San Luis Obispo Creek, located approximately 190 feet west of the intersection of Prado Road and South Higuera Street in the City of San Luis Obispo. This project would replace the existing narrow and substandard bridge with a wider, four through - lane bridge with shoulders, additional turn lanes, protected bike lanes, and sidewalks. The existing two-lane Prado Road Bridge over San Luis Obispo Creek is currently structurally deficient and has no bicycle or pedestrian facilities. Traffic studies also indicate that the bridge is not wide enough to accommodate existing and projected future traffic demands. This project is intended to provide a safer, more accessible route for local businesses, residents, commuters, and visitors into the future. This project will be primarily funded through both local City and FHWA's HBP funds. The current escalated total project cost is estimated to be $45,500,000. Prado Creek Bridge 1 VA Study Summary Report Page 988 of 1059 PROJECT PURPOSE AND NEED The City of San Luis Obispo (SLO) is replacing the bridge with a wider structure that will add improvements to provide safe access to drivers, bicyclists, and pedestrians, better accommodate creek flow, and accommodate anticipated traffic for years to come. The project will include multi - modal improvements to South Higuera at Prado Road. Planned for construction starting in 2027, the Prado Road Bridge Widening Project improvements will pave the way for a brighter, bustling southern district of SLO. This project provides the opportunity to plan for the future using state-of-the-art infrastructure and forward -thinking design. It sets the stage for an even larger future endeavor, which is the long -planned Prado Road Interchange Project, a critical infrastructure project that will provide a new crossing over US 101 between Madonna Road and Los Osos Valley Road. VA STUDY TIMING The VA study was conducted during the late stages of the design phase of the project, which is currently to be completed later this year (2026). The project is scheduled for Ready to List (RTL) in summer 2027. The project construction duration is anticipated for 3 seasons, running from Construction Start in late 2027 to Construction Completion by fall of 2029. VA STUDY OBJECTIVES The objectives of the VA study were to: 1. Analyze the current project design, estimate, and schedule 2. Provide possible cost and/or schedule saving recommendations 3. Provide performance improvement recommendations KEY PROJECT ISSUES The items listed below are the key drivers, constraints, or issues being addressed by the project and considered during this VA study to identify possible improvements. Project Budget — The total project cost is currently estimated at $45.5M and will tap funding from several sources — including the federal government through Caltrans. A significant amount of the project will be funded by the City of San Luis Obispo. Present Need vs Potential Need —The present design is a full build approach that is scaled to accommodate the upcoming improved interchange with Highway 101 and is expected to provide capacity for the anticipated development and growth to the east of the Higuera Street - Prado Road intersection including a long-term planning connection of Prado to Broad St. The project must balance the present need and the potential need when determining what to include in the current project design, especially regarding which facility elements to fund with this project. It should be noted that coordination with the upcoming Prado Road/Highway 101 interchange project is a priority Prado Creek Bridge 2 VA Study Summary Report Page 989 of 1059 for the success of this project. Utility Improvement and Relocation — The current design will require maintaining nearly all the existing utilities that run through the intersection and across the current bridge until they can be relocated to their permanent new locations. Overhead utilities will be undergrounded in a joint trench. Additionally, the project will take the opportunity to improve stormwater management along S. Higuera Street. The utility work requires significant coordination with the utility companies and will encompass the majority of the first stage of the project with traffic handling and construction impacts anticipated. EVALUATION OF BASELINE CONCEPT During the VA study, a number of analytical tools and techniques were applied to develop a better understanding of the baseline concept. A Performance Attributes major component of this analysis was Value Metrics, which seeks to Traffic Operations assess the elements of cost, performance, time, and risk as they related to project value. These elements require a deeper level of analysis, the Multi -Modal Operations results of which are detailed in the Project Analysis section of this Maintainability report. The key performance attributes identified for the project are listed in the table, "Performance Attributes." A summary of the major Long -Term Impacts observations and conclusions identified during the evaluation of the baseline concept, which led the VA team to develop the alternatives Construction Impacts and recommendations presented in this report follows. The stakeholders rated the five performance attributes as each having a major contribution to the success of the project. Through a paired comparison process, study participants determined that Traffic Operations was weighted the highest at 29% as the project is primarily about establishing a significant useful life for the bridge and improving the traffic operations along Prado Road and its connection with Higuera Street. Multi -Modal Operations is the next highest rated attribute at 26% due to the importance of integrating effective bicycle and pedestrian facilities within the project. Both Maintainability and Long -Term Impacts were rated on the next tier of importance at 16% each. Construction Impacts was relatively weighted the lowest at 13% but was still viewed as being important to the overall success of the project. The initial evaluation of the current basis, or baseline concept, for the project by the stakeholders determined that it represents an effective and responsible approach to replace the aging bridge structure while fulfilling the project's purpose and need to provide safe access for drivers, bicyclists and pedestrians, and accommodate anticipated traffic for years to come. Although there are still some details that need to be further developed, the five performance attributes scored higher than typical projects of this nature and prove that a great deal of work and effort have been applied to the current design. The baseline concept should address current and future traffic volume needs and provide a bridge with the useful life needed by the project. The completed bridge, roadway, bike path, utility, and intersection design will improve the future operation of the mainline facility by bringing the facilities up to current standards. Most of the short-term Construction Impacts, such as traffic disruption and temporary access loss, are unavoidable for a project of this nature. The short- Prado Creek Bridge 3 VA Study Summary Report Page 990 of 1059 term environmental impacts will be mitigated and addressed through careful planning and avoidance measures. The project's long-term impacts were environmentally cleared and mitigated while the project will improve the overall hydraulics of the crossing. Overall, the stakeholders concluded that this baseline concept for the project was good and addressed many of the key concerns admirably; however, there is still room for potential project value improvement, especially regarding how to provide the right balance of current effective transportation facilities for the community while responsibly utilizing the limited funding sources available. VA ALTERNATIVES The VA team developed 7 VA alternatives for improvement of the project. The following are the alternatives identified, along with their associated potential initial cost savings, potential change in schedule, performance change, and a brief discussion of each. Alternative No. and Description Initial Cost Change in Change in Savings Schedule Performance 1.0 Reduce overall width of Prado Creek Bridge $3,000,000 2-week - 3.5 reduction The alternative concept proposes reducing the overall width of the new Prado Creek Bridge by 23' (from 114' to 91'). This reduction would be accomplished by eliminating an eastbound through lane, reducing travel lane widths from 12' to 11', reducing the median width, and simplifying the bicycle and pedestrian facility design. 2.0 Remove undergrounding of overhead utilities from $500,000 No change - 0.7 project The alternative concept proposes to remove the undergrounding of the electrical and communication lines from the project. This will require the utilities to be relocated from their existing lines to new overhead alignments in the public R/W at the utility owners' expense. The project will still require the construction of a joint trench and ducting for the other fiber communication lines. 3.0 Reduce minimum depth of cover of joint trench $100,000 No change + 0.2 from 7' to 3' The alternative concept proposes to reduce the minimum amount of cover over the joint trench from 7' to 3' in specific locations. The joint trench locations that can be reduced are limited to the S. Higuera Street and the western Prado Road segments and only when the joint trench is running parallel to road centerline and not crossing transverse (in other words, can be done when not in conflict with other underground utilities). Prado Creek Bridge 4 VA Study Summary Report Page 991 of 1059 4.0 Limit sewer, recycled water, and potable water utility relocation $300,000 No change - 0.3 The alternative concept proposes to address the wet utility relocation (the sewer line, recycled water line, and potable water) for the bridge segment only and extending westerly to the Higuera/Prado intersection only (sewer). The Higuera Street water utility relocation would be removed from this project and deferred to a later project. 5.0 Use RSP to eliminate the retaining wall $2,000,000 No change + 0.9 underneath the bridge The alternative concept proposes to use rock slope protection (RSP) underneath the new bridge in lieu of soldier pile wall sections which will need to be studied for hydraulic viability. The RSP would tie into the remaining soldier pile wall sections that are constructed away from the bridge along each slope. 6.0 Reduce raised Prado Road median length on $20,000 No change + 0.4 bridge The baseline concept includes a raised median that extends for the full length of the bridge, widening as it moves from east to west. The alternative concept proposes to shorten and narrow the raised median. 7.0 Remove and do not replace the Bob Jones Trail $150,000 No change + 0.9 Bridge The baseline concept is to remove the Bob Jones Trail Bridge (BJTB) during the demo and reconstruction of the new Prado Creek Bridge, store the BJTB onsite, improve the BJTB abutments, and then return the BJTB to its original location (the western abutment will remain as is. The eastern abutment will be relocated, so the BJTB will be in a slightly rotated position compared to existing). The alternative concept proposes to remove the Bob Jones Trail Bridge permanently from the project location. VA STUDY RESULTS The VA team identified 2 VA strategies (combinations of VA alternatives) for consideration by the PDT and City of San Luis Obispo decision -makers. The 2 VA strategies take a layered approach to improving upon the value of the project's baseline design and include a "minimum build" strategy (VA Strategy 1) and a "maximum savings" strategy (VA Strategy 2). VA Strategy 1 uses VA Alternative 1 to narrow the bridge structure to only what is expected to be required to meet current traffic volume expectations in support of the upcoming Prado Interchange project. This strategy is not anticipated to affect the amount of funding that the project will receive from the HBP program but will instead reduce the funding portion needed directly from the City of Prado Creek Bridge S VA Study Summary Report Page 992 of 1059 San Luis Obispo. Under this strategy, it is anticipated that any additional widening of the bridge needed for the bridge and intersection can be accomplished at a later date when the need becomes more evident (such as the through -connection to Broad Street). VA Strategy 2 uses all the developed VA alternatives to reduce the total initial project cost in a reasonable and practical manner. The alternatives collected in this strategy include the bridge narrowing alternative (VA Alternative 1) but would also include the following modifications: defer or eliminate some of the utility work in the baseline design (VA Alternatives 2.0, 3.0, & 4.0), simplify the retaining wall design under the bridge in favor of RSP (VA alternative 5.0 - which will need to be studied for hydraulic viability), and remove a few additional design elements from both the roadway (VA Alternative 6.0) and the Bob Jones Trail (VA Alternative 7.0). This strategy would be expected to reduce the amount of funding required by the City and the HBP program. Despite each strategy reducing construction -related impacts to the project area, the strategies result in a net reduction in performance when compared to the baseline (a -3.5% for VA Strategy 1 and - 2.1% for VA Strategy 2). This is primarily due to the removal of some of the vehicular and multi -modal elements from the highly rated, full -build baseline design. Overall value, however, is improved over the baseline design by the VA strategies (1.4% and 8.0%, respectively) when the cost savings and schedule savings are included in the value calculation. Summary of Recommended VA Strategies Strategy Description Initial Cost Savings Change in Schedule Change in Performance Value Change VA Strategy 1— Narrow Bridge 2-week Only/Minimum Build $3,000,000 - 3.5 % + 1.3 % reduction Alternative 1.0 VA Strategy 2 — Maximum Savings 2-week Alternatives 1.0, 2.0, 3.0, 4.0, 5.0, $6,070,000 - 2.1 % + 8.0 % reduction 6.0, & 7.0 A summary of the two VA strategies is provided in the following table and chart. The chart illustrates the relative trade-offs between performance (shown by the blue columns) versus cost and schedule (shown by the yellow and green columns, respectively). The red value line indicates the net % change in total value relative to the baseline concept. Please refer to the Project Analysis section of the report for additional details on this analysis. Prado Creek Bridge 6 VA Study Summary Report Page 993 of 1059 Comparison of Value Baseline Concept & Recommended VA Strategies 10 100 % 9 90 % 8 80 % 7 70 % 6 60 % 5 50 % 4 40 % 3 30 % 2 20 % 0 0 0.0% 1.3 % • o 0 0 • 0% Baseline Concept VA Strategy #1 VA Strategy #2 Perf. Cost � Time —•—Value % A VA TEAM VA Study Team Name Organization Title Eric Trimble VMS, Inc. VA Study Facilitator Jorge Aguilar Wallace Group Project Manager Sarah Huffman Wallace Group Project Engineer, Roadway Design Ethan Pence Wallace Group Roadway Design Steven Tanaka Wallace Group Project Engineer, Sewer/Water Design Travis Vasquez Wallace Group Sewer/Water/Recycled Water Design Scott McCauley Consor Structures Lead Matt Vaggione Consor Project Engineer, Structures Thomas Truchement Consor Structures Design Brent Lemon Consor Transportation Design Specialist Judd King Yeh & Assoc. Geotechnical Engineer Lyle Nemeth Filippin Engin. Constructability Joe Fernandez CCTC CCTC - Traffic Analysis Lead/Electrical Design Prado Creek Bridge 7 VA Study Summary Report Page 994 of 1059 Name Organization Title Michelle Matson CCTC CCTC -Traffic Analysis/Electrical Design Key Project Contacts Name Organization Title Matt Horn City of SLO Project Manager Brian Nelson City of SLO Dep. Director of Public Works - City Engineer Luke Schwartz City of SLO Traffic & Active Transportation - Peds & Bikes Miguel Barcenas City of SLO Utilities Prado Creek Bridge 8 VA Study Summary Report Page 995 of 1059 VA ALTERNATIVES Page 996 of 1059 VA ALTERNATIVES PRELIMINARY The results of this study are presented as individual alternatives to the baseline concept. Each alternative consists of a summary of the baseline concept, a description of the suggested change, a listing of its advantages and disadvantages, a cost comparison, change in performance and value, discussion of schedule and risk impacts (if applicable), and a brief narrative comparing the baseline design with the alternative. (Please refer to the Project Analysis section of this report for an explanation of how the performance attributes and value are calculated.) Sketches, calculations, and performance attribute ratings are also presented where applicable. The cost comparisons reflect a similar level of detail as in the baseline estimate. VA STRATEGIES VA studies result in the development of a number of alternatives. While it is possible for all alternatives to be implemented, typically there are combinations of some alternatives that may provide the best solution for the project. This is due to the fact that some alternatives may be competing ideas or different ways to address the same issue. Some alternatives are developed to answer a question raised by a decision -maker or to resolve an open issue and are found not to be beneficial to the ultimate project. As a result of these factors, the VA team developed two VA strategies that represent their opinion of the best combination of alternatives for the project to assist the decision -makers in their evaluation of the VA alternatives. The VA strategies are based on factors that include improved performance, likelihood of implementation, least community impact, cost savings, or any combination of the project's performance attributes. This information is a guide and is not intended to reject the other alternatives from project stakeholder consideration. VA ALTERNATIVE SUMMARY TABLES Summary of VA Alternatives Initial Cost Change in Performance Value Alternative No. &Description Savings Schedule Change Change 2-week 1.0 Reduce overall width of Prado Creek Bridge $3,000,000 - 3.5 % + 1.3 % reduction 2.0 Remove undergrounding of overhead utilities No $500,000 - 0.7 % + 0.1 from project change 3.0 Reduce minimum depth of cover of joint No $100,000 + 0.2 % + 0.3 trench from 7' to 3' change Prado Creek Bridge 9 VA Alternatives Page 997 of 1059 4.0 Limit sewer, recycled water, and potable No $300,000 - 0.3 % + 0.2 water utility relocation change 5.0 Use RSP to eliminate the retaining wall No $2,000,000 + 0.9 % + 3.8 underneath the bridge change 6.0 Reduce raised Prado Road median length on No $20,000 + 0.4 % + 0.5 bridge change 7.0 Remove and do not replace the Bob Jones No $150,000 + 0.9 % + 1.2 Trail Bridge change Summary of VA Strategies Initial Cost Change in Performance Value Strategy Description Savings Schedule Change Change VA Strategy 1— Narrow Bridge Only/Minimum 2-week Build $3,000,000 - 3.5 % + 1.4 % reduction Alternative 1.0 VA Strategy 2 — Maximum Savings 2-week Alternatives 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 & 7.0 reduction OTHER CONSIDERATIONS The VA team identified the following observations and design suggestions, relatively general in nature, for consideration by the Project Development Team (PDT). More detailed descriptions can be found in the Ideal Evaluation portion of this report. OC-1: Introduce contracting language to allow for alternative methods of temporary utility support (MU-10) This concept would seek to allow the contractor more flexibility in proposing a method to eliminate the temporary utility bridge across the Creek during the construction of the new Prado Creek Bridge by adding it into the contracting language. Prado Creek Bridge 10 VA Alternatives Page 998 of 1059 OC-2: Modify wall type and reduce length of retaining wall outside of bridge (RE-1) This concept would explore the use of a tangent pile wall design in lieu of the soldier pile design for the retaining wall beyond the bridge. The use of the tangent pile retaining wall system might reduce the amount of excavation required down to scour depth and eliminate the horizontal lagging; it would also allow for the wall to be shortened in either direction away from the bridge. OC-3: Modify wall type for the retaining wall underneath the bridge (RE-2) This concept would explore the use of a tangent pile wall design in lieu of the soldier pile design for the retaining wall immediately under the bridge. As mentioned prior, the use of the tangent pile retaining wall system might reduce the amount of excavation required down to scour depth and eliminate the horizontal lagging. OC-4: Reduce/remove green pavement markings (AB-4) This concept would simply reduce or remove the green pavement markings from the project to reduce the initial cost of the project. The markings are not a requirement for the operation of the bikeways. OC-5: Remove colored concrete and reduce thickness from Class IV bikeways (AB-9) This concept would reduce the concrete thickness of the Class IV bikeways and eliminate the colored concrete to reduce the initial cost of the project. These items are not a requirement for the operation of the bikeways. OC-6: Delay schedule to align construction with interchange project (CP-1) This concept would explore the benefits of more closely aligning the Prado Creek Bridge project and the Prado Interchange project so that more construction efficiencies could be attained and overall, less public impact duration might be experienced by the two projects construction periods being overlapped with each other. The two projects being closer in time may also make them more appealing to a single contractor as they may be able to mobilize for both projects consecutively. The Prado Creek Bridge project must be completed prior to the interchange project, but to more closely align, it would need to be delayed a year, which may present funding or approval issues. OC-7: Reduce architectural treatments on bridge (EA-1) This concept would seek to reduce the initial expense of the project by simplifying the architectural treatments on the bridge. A straightforward bridge design would have less curb appeal for the local community but would help to reduce the project cost. Prado Creek Bridge 11 VA Alternatives Page 999 of 1059 SUMMARY OF PERFORMANCE IMPROVEMENTS The Caltrans HQ VA Program requires the following information to enable reporting of performance to the FHWA. Only the six standard Caltrans performance attributes, shown in the table below, are to be documented. Caltrans does not require reporting of the performance of any other attributes utilized in this study. Summary of Proposed VA Alternative Performance Improvements Multi -Modal Long-Term ConstructionTraffic Project Alt. No. Environmental Maintainability Connectivity Impacts Operations Schedule Impacts 1.0 Improved Improved Improved Improved 2.0 Improved 3.0 4.0 Improved Improved 5.0 Improved Improved Improved 6.0 Improved 7.0 Improved Improved Improved Prado Creek Bridge 12 VA Alternatives Page 1000 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge Initial Cost Savings: $3,000,000 Change in Schedule: 2-week reduction Performance Change Value Change + 1.3 % Description of Baseline Concept: The baseline concept replaces the existing Prado Creek Bridge with a new single -span precast girder bridge that is 142' long and 114' wide. The new bridge will accommodate 6 lanes of vehicular traffic for Prado Road with sidewalks and sidewalk level Class IV and on -street shoulder Class II bike lanes on either side. The current width of this new bridge will require the relocation of the Bob Jones Trail Bridge during and after construction. Description of Alternative Concept: The alternative concept proposes to reduce the overall width of the new Prado Creek Bridge through the following concepts: • The elimination of the eastbound through -lane • The use of sidewalk and shoulder in lieu of Class IV on the north side • The use of a Class I bike lane in lieu of a protected bikeway (Class IV) and sidewalk on south side • Reduction of all travel lanes on the bridge from 12' to 11' The resulting total width of the bridge would be 91', whereas the length of the new bridge would be maintained at 142'. The new bridge width would be comprised of the following design elements: • A 4' median • Five 11' travel lanes • Two 5' outside shoulders • A 6' sidewalk on the north side • A 14' combined path on the south side • Two 1' bridge rails Additionally, this concept would result in the following indirect impacts to the overall project design: • Elimination of the second eastbound lane on Prado Road east of Higuera Street • Maintained roadway width but elimination of one of the Southbound S. Higuera left -turn lane to eastbound Prado Road • Elimination of the Class IV bike facilities on Prado Road east of Higuera Street Prado Creek Bridge 13 VA Alternatives Page 1001 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge This 23' bridge reduction (and partial shift northward in its alignment) may allow for the Bob Jones Trail Bridge to remain in place during construction — which would avoid the need to remove, upgrade, and relocate the bridge as part of the project. Advantages: • Traffic Operations — Improved by reduced wait times at intersection • Multi -modal Operations — Improved by reduced distance/wait times for pedestrian crossings at intersection • Construction Impacts — Improved by reduction in bridge structure and roadway construction. Eliminates need to relocate Bob Jones Trail Bridge. Assume schedule reduction of 2 weeks (3.8 — 5.0) • Long -Term Impacts — Improved aesthetic by reducing overall scale of bridge (6.6 — 7.0) • Maintainability — Improved by reducing size and number of assets to maintain in future. Less stormwater volume (6.4 — 7.0) Disadvantages: • Traffic Operations — Degraded by reduction in capacity and flexibility for future traffic volume growth (7.7 — 6.5) • Multi -Modal Operations — Degraded by reduction in capacity and losing buffer from traffic (7.8 — 7.0) • Construction Impacts — Degraded by keeping the Bob Jones Trail Bridge constraining structure work • Long -Term Impacts — Degraded by constraining future growth in the near term • Maintainability — Degraded by reducing roadway space for performing future roadway maintenance Discussion: The main benefit of this proposed alternative concept is to significantly reduce the initial project cost and to simplify the overall construction of the project. Discussions during the VE study determined that many of the features of the full build design concept are not required by near term traffic volumes and would not likely be needed until a Prado Rd. connection to Broad Street is constructed. These improvements are not anticipated in the next 10-15 years (and may not occur at all). This discussion led to the development of this concept, which more properly matched the design to the traffic volume that is more immediately needed with the connection to the upcoming US-101 interchange project. Discussion of Schedule Impacts: This alternative concept represents a small impact to the project schedule's critical path as the bridge construction effort and in -water work is still a controlling and integral part of the work being performed. By reducing the overall width of the bridge, a schedule reduction of 2 weeks was Prado Creek Bridge 14 VA Alternatives Page 1002 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge conservatively estimated. Discussion of Risk Impacts: The alternative concept represents a reduction to the construction -related project risk as the in - water work and bridge work will be reduced, along with the project duration being shortened by two weeks. The alternative concept represents an increase in future operational facility risk by reducing the overall capacity to handle vehicular traffic in the future should growth and a future regional connection of Prado to Broad Street on the east materialize. Additionally, the reduction in facility widths — both on and off the bridge — will reduce the amount of space available for future maintenance efforts and traffic handling flexibility. Prado Creek Bridge 15 VA Alternatives Page 1003 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge Ic "A.D,.'HT UcRN ON Baseline Concept Image I A Image showing portions of the current full build bridge and intersection design for the project Prado Road Brwge l wening Current Design Right -of -Way 114 of 114 feet Length 1 0 mi Wallace Group ♦streetplan.,e Image showing baseline design cross-section Prado Creek Bridge 16 VA Alternatives Page 1004 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge Alternative Concept Image Image showing those bridge and roadway design elements (in red/yellow) that could be eliminated or modified by the proposed bridge width reduction. White text boxes denote proposed bicycle path modifications Prado Road a,agewiaenng Bridge Widening Reduction Right -of -Way 91 of 91 feet Length: 10 mi Wallace Group j i5,,�r; ,AWL. Image showing proposed cross-section Prado Creek Bridge 17 VA Alternatives Page 1005 of 1059 VA ALTERNATIVE 1.0 (SD-1) Reduce overall width of Prado Creek Bridge Assumptions and Calculations: The initial cost assumption of the alternative concept: • Reduction of the overall bridge width by 23' (includes reduction of in -creek work, falsework, concrete and concrete curing, roadway materials, and removal of falsework, striping, and paint) • Reduction of Prado Road width east and west of bridge (roadway excavation & roadway structural section) • Reduction in traffic handling • Reduction in project duration and time -related overhead of 2 weeks A total cost reduction of between $2-3M was discussed. An aggressive $3M cost savings was applied for the Value Metrics calculation. The funding for this portion of the bridge is separate from the federal funding received for the project as the federal funding provides for 5 lanes of bridge width. Prado Creek Bridge 18 VA Alternatives Page 1006 of 1059 VA ALTERNATIVE 2.0 (MU-2) Remove undergrounding of overhead utilities from project Initial Cost Savings: $500,000 Change in Schedule: No change Performance Change - 0.7 Value Change + 0.1 Description of Baseline Concept: The baseline concept includes the temporary and permanent relocation of local utilities in the project area, including a sewer line, a recycled water line, a potable water line, electrical service lines, and several fiber communication lines. The sewer, recycled water, and potable water lines will be routed under the new bridge structure. The electrical lines will be undergrounded and gathered together with the communication lines, placed in separate conduits, and routed through the bridge structure. The electrical and fiber lines will be placed in a shared trench on either side of the bridge with a top depth of 7'. Description of Alternative Concept: The alternative concept proposes to remove the undergrounding of the electrical and communication lines from the project. This will require that the existing utility lines be relocated to new overhead alignments in the public R/W (right-of-way) at the utility owners' expense. The project will still require the construction of a joint trench and ducting of some of the other fiber communication lines. Advantages: • Construction Impacts — Improved by removing the undergrounding component of the electrical and some of the fiber utility work from the project. The size of the joint trench can be reduced, and this reduces utility coordination (3.8 — 3.9) Disadvantages: • Multi -modal Operations — Degraded by maintaining poles, which will impede the pedestrian and bicycle travel area (7.8 — 7.7) • Construction Impacts — Degraded by impeding the use of cranes during construction • Long -Term Impacts — Degrades the local aesthetics by maintaining poles and overhead lines (6.6 — 6.5) • Maintainability — Degraded by maintaining maintenance of overhead utilities into the future and additional potential for damage to these overhead utilities (6.4 — 6.3) Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project by removing the utility undergrounding component. It was discussed during the VE study that, although the undergrounding of electrical and telecom utilities is a desired aspect and the project provides an Prado Creek Bridge 19 VA Alternatives Page 1007 of 1059 VA ALTERNATIVE 2.0 (MU-2) Remove undergrounding of overhead utilities from project opportunity to address this condition, it does not represent a requirement or an essential element of the project. Discussion of Schedule Impacts: Although the removal of the undergrounding work would provide additional flexibility for the contractor in completing the utility work for the project, it does not represent a critical path element for the project schedule. Discussion of Risk Impacts: The alternative concept represents a minor reduction to the construction -related project risk as the utility work will be reduced. The alternative concept represents a minor increase in future operational facility risk by increasing the potential for overhead utility lines to be damaged by weather or accident, which would require otherwise avoidable repair work and/or possible facility operational downtime. Assumptions and Calculations: The initial cost assumption of the alternative concept: • Eliminate undergrounding of all overhead utilities • Assumes no impact to the overall project duration A total cost reduction of $500K was applied for the Value Metrics calculation. The funding for this project element is separate from the federal funding received for the project. Prado Creek Bridge 20 VA Alternatives Page 1008 of 1059 VA ALTERNATIVE 3.0 (MU-3) Reduce minimum depth of cover of joint trench from 7' to 3' Initial Cost Savings: $100,000 Change in Schedule: No change Performance Change + 0.2 Value Change + 0.3 Description of Baseline Concept: The baseline concept includes the temporary and permanent relocation of local utilities in the project area including a sewer line, a recycled water line, a potable water line, electrical service lines, and several fiber communication lines. The sewer, recycled water, and potable water lines will be routed under the new bridge structure. The electrical lines will be undergrounded and gathered together with the communication lines, placed in separate conduits, and routed through the bridge structure. The electrical and fiber lines will be placed in a shared trench on both sides of the bridge with a top depth of 7' minimum. There is currently 2,800 LF of joint trenching for utilities. Description of Alternative Concept: The alternative concept proposes to reduce the minimum amount of cover over the joint trench from 7' to 3' in specific locations. The joint trench locations that can be reduced are limited to the S. Higuera Street and the western Prado Road segments and only when the joint trench is running parallel to road centerline and not crossing transverse (in other words, can be done when not in conflict with other underground utilities). Advantages: • Construction Impacts — Improved by reducing trenching and shoring required by the contractor (3.8 — 3.9) • Maintainability— Improved by shallower depth of repairs if needed (minor improvement) Disadvantages: • None noted Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project. The trench depth can be decreased along Higuera Street south and Prado Road west of the intersection as the amount of other buried utilities in the area is limited and the potential for utility conflicts should be greatly diminished. Prado Creek Bridge 21 VA Alternatives Page 1009 of 1059 VA ALTERNATIVE 3.0 (MU-3) Reduce minimum depth of cover of joint trench from 7' to 3' Discussion of Schedule Impacts: Although the removal of the undergrounding work would provide additional flexibility for the contractor in completing the utility work for the project, it does not represent a critical path element for the project schedule. Discussion of Risk Impacts: The alternative concept represents a minor reduction to the construction -related project risk as the utility trenching work will be reduced. The alternative concept represents a minor increase in future operational facility risk by increasing the potential for accidental damage by near -surface roadway or utility work, which would require otherwise avoidable repair work and possible facility operational downtime. Prado Creek Bridge 22 VA Alternatives Page 1010 of 1059 VA ALTERNATIVE 3.0 (MU-3) Reduce minimum depth of cover of joint trench from T to 3' Baseline/Alternative Concept Image i '71f LE E: I� f I -iE 1r-TI 'TN TE: . IT[LIT, fl T E LETS ,M TEFL L-TE . I . ,II TMI-, - JCEPTUAL STAGING PLANS 3NTRACTOR TO DEVELOP ACTUAL STAGING PLAN Image showing the affected trenching area - Higuera Street south of intersection and Prado Road west Prado Creek Bridge 23 VA Alternatives Page 1011 of 1059 VA ALTERNATIVE 3.0 (MU-3) Reduce minimum depth of cover of joint trench from 7' to 3' Assumptions and Calculations: The initial cost assumption of the alternative concept: • Reduce depth of trenching and protective shoring by 4' • Assumes no impact to the overall project duration A total cost reduction of $100K was applied for the Value Metrics calculation. The funding for this project element may be considered as part of the federal funding package received for the project. Prado Creek Bridge 24 VA Alternatives Page 1012 of 1059 VA ALTERNATIVE 4.0 (MU-5) Limit sewer, recycled water, and potable water utility relocation Initial Cost Savings: $300,000 Change in Schedule: No change Performance Change - 0.3 Value Change + 0.2 Description of Baseline Concept: The baseline concept includes the temporary and permanent relocation of local utilities in the project area, including a sewer line, a recycled water line, a potable water line, electrical service lines, and several fiber communication lines. The sewer, recycled water, and potable water lines will be routed under the new bridge structure. Description of Alternative Concept: The alternative concept proposes to address the wet utility relocation (the sewer line, recycled water line, and potable water) for the bridge segment only and extending westerly to the Higuera/Prado intersection only (sewer). The Higuera Street water utility relocation would be removed from this project and deferred to a later project. Advantages: • Construction Impacts — Improved by reducing the amount of trenching and shoring required and providing additional utility work flexibility for the contractor in Stage 1 (3.8 — 3.9) Disadvantages: Maintainability — Degraded by increasing the amount of maintenance work on existing (older) utilities, as well as disruptions in future years to traffic and community for deferred utility work (6.4 — 6.2) Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project. The wet utility work east of the Prado Creek Bridge would be deferred to a later time. Discussion of Schedule Impacts: The removal of the wet utility work east of the new bridge would greatly impact the project schedule but would not ultimately equate to a reduction in the project schedule's critical path as the bridge and roadway work is already scheduled for Spring of 2028 through Summer 2029. Discussion of Risk Impacts: The alternative concept represents a significant reduction to the construction -related project risk as Prado Creek Bridge 25 VA Alternatives Page 1013 of 1059 VA ALTERNATIVE 4.0 (MU-5) Limit sewer, recycled water, and potable water utility relocation the utility work will be greatly reduced, which will decrease the amount of traffic handling and the potential for traffic conflicts between the public and the contractor. The alternative concept represents an increase in future operational facility risk by deferring the utility work and its required traffic handling and potential traffic conflicts to a later period. Baseline/Alternative Concept Image STAGE 1 - UTILITIES CONCEPTUAL STAGING PLANS CONTRACTOR TO DEVELOP ACTUAL STAGING PLAN Image showing the utility work locations at the intersection, along Higuera Street north and south, as well as Prado Road west and east of the bridge Prado Creek Bridge 26 VA Alternatives Page 1014 of 1059 VA ALTERNATIVE 4.0 (MU-5) Limit sewer, recycled water, and potable water utility relocation Assumptions and Calculations: The initial cost assumption of the alternative concept: • Elimination of the wet utility work not being relocated under the new bridge, which will carry the sewer line, recycled water line, and potable water line • Sewer line work extending westerly to existing MH J15-11 would still be required • Assumes no impact to the overall project duration A total cost reduction of $300K was applied for the Value Metrics calculation. The funding for this project element may be considered as part of the federal funding package received for the project. Prado Creek Bridge 27 VA Alternatives Page 1015 of 1059 VA ALTERNATIVE 5.0 (RE-3) Use RSP to eliminate the retaining wall underneath the bridge Initial Cost Savings: $2,000,000 Change in Schedule: No change Performance Change + 0.9 Value Change + 3.8 Description of Baseline Concept: The baseline concept uses a soldier pile retaining wall with precast concrete lagging to support the slope under each side of the new bridge. Description of Alternative Concept: The alternative concept proposes to use rock slope protection (RSP) underneath the new bridge in lieu of soldier pile wall sections which will need to be studied for hydraulic viability. The RSP would tie into the remaining soldier pile wall sections that are constructed away from the bridge along each slope. Advantages: • Construction Impacts — Improved by simplifying the construction process of the retaining wall, reducing steps, removing some of the horizontal lagging, and being less overall work for contractor (3.8 — 4.0) • Long -Term Impacts — Improved by potentially improving or maintaining hydraulic flow under the bridge, reducing environmental disturbance impacts, and enhancing aesthetics (6.6 — 6.7) • Maintainability — Easier to maintain the RSP than the retaining wall (6.4 — 6.5) Disadvantages: • Maintainability — Degraded by more frequent maintenance effort Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project while simplifying the construction process. This alternative would allow for the retaining wall in front of the abutment to be eliminated. It is important to note that this alternative may have an impact on the hydraulic characteristics of the creek flow under the bridge. This should be investigated with a hydraulics analysis by the team to ensure that the impact of this design change does not increase the chance of erosion of the creek slopes or the scour of the bridge supports. The potential impacts to the hydraulics presented by this concept can be mitigated (or improved) as needed by modifying the location and configuration of the abutment on the west side. Prado Creek Bridge 28 VA Alternatives Page 1016 of 1059 VA ALTERNATIVE 5.0 (RE-3) Use RSP to eliminate the retaining wall underneath the bridge Discussion of Schedule Impacts: Although the removal of the soldier pile retaining wall under the bridge would provide additional flexibility for the contractor in completing the in -water work for the project, it does not represent a critical path element for the project schedule. Discussion of Risk Impacts: The alternative concept represents a minor reduction to the construction -related project risk as the in -water work will be reduced. The alternative concept represents no significant future operational work. The RSP may need to be adjusted or added to in the future, but this is anticipated to be equivalent to ongoing maintenance work with the retaining wall. Alternative Concept Images The use of RSP in lieu of soldier pile retaining wall under the bridge The use of RSP in lieu of soldier pile retaining wall under the bridge Prado Creek Bridge 29 VA Alternatives Page 1017 of 1059 VA ALTERNATIVE 5.0 (RE-3) Use RSP to eliminate the retaining wall underneath the bridge Assumptions and Calculations: The initial cost assumption of the alternative concept: • Reduce the amount of soldier pile wall (excavation, pile driving, piles, lagging, and backfill) • Increase the amount of rock slope protection and placement • Assumes no impact to the overall project duration A total cost reduction of $2M was applied for the Value Metrics calculation. The funding for this project element may be considered as part of the federal funding package received for the project. Prado Creek Bridge 30 VA Alternatives Page 1018 of 1059 VA ALTERNATIVE 6.0 (CT-1) Reduce raised Prado Road median length on bridge Initial Cost Savings: $20,000 Change in Schedule: No change Performance Change + 0.4 Value Change + 0.5 Description of Baseline Concept: The baseline concept includes a raised median that extends for the full length of the bridge — widening as it moves from east to west. Description of Alternative Concept: The alternative concept proposes to shorten and narrow the raised median. Advantages: • Traffic Operations— Improved by providing additional movement flexibility (7.7 — 7.8) • Construction Impacts — Improved by reduction in raised median construction (3.8 — Push) • Maintainability— Improved by reduced raised median to maintain (6.4— Push) Disadvantages: • None noted Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project while simplifying the construction effort. The new alignment of the raised median will still need to serve to negate the left -turn out movement from the affected property at 3380 S Higuera St. Discussion of Schedule Impacts: Although the reduction of the median would provide additional flexibility for the contractor in completing the roadway work west of the bridge, it does not represent a critical path element for the project schedule. Discussion of Risk Impacts: The alternative concept represents a negligible reduction to the construction -related project risk as the pavement work will be reduced. The alternative concept represents a negligible reduction of the future operational risk related to future maintenance efforts. Prado Creek Bridge 31 VA Alternatives Page 1019 of 1059 VA ALTERNATIVE 6.0 (CT-1) Reduce raised Prado Road median length on bridge Baseline Concept Image Image showing current full build design, including the full center median design Alternative Concept Image .,.,a111111'j ON 4�. � Illllrl�l Bill �� � � ail;• ii1 , ��`,O TYPE Y YYIp TYPE YI YMO. T-�•__.. Ml- P6YEY[Nl OELINE6TION T.0' L• �rLf. , _ , � -I OETYL PEA ST-- PLYYs. 6• rELLOE TxEracn,.snc rNYrl< sMIPE (EA06EM s-6) C .•e� T , .I 1 OIE-NT CADSS.IEE (SEE OEf61l Txls slEEll f+ - 39.2' LY 1 6 6 1p.61 tlYsS)ISE ISEE pET61L THIS LE[il lI • 6 I _ _ _ T' I s'aI.s' 611ELN )ILE.6Y YWtIMO Y6CEU EYEM 6.5' 2T..' Lt En'EEAED EIxE LYE ISEE KT61L THIS SHEET) 6- YE- TEPWPL65TIC -IC SMIPE I20' O.C.. 65.1 6- MITE TEAIgPl Ic MYEIC sMIPE 16' O.C. 6r xE0 P61N1 CURB 13-[0611 �-'- I � 2r Image showing a reduction of the center median Prado Creek Bridge 32 VA Alternatives Page 1020 of 1059 VA ALTERNATIVE 6.0 (CT-1) Reduce raised Prado Road median length on bridge Assumptions and Calculations: The initial cost assumption of the alternative concept: • Reduce center median on Prado Road on the new bridge and west of the bridge • Assumes no impact to the overall project duration A total cost reduction of $20K was applied for the Value Metrics calculation. The funding for this project element is not included in the federal funding package received for the project. Prado Creek Bridge 33 VA Alternatives Page 1021 of 1059 VA ALTERNATIVE 7.0 (AP-1) Remove and do not replace the Bob Jones Trail Bridge Initial Cost Savings: $150,000 Change in Schedule: No change Performance Change + 0.9 % Value Change + 1.2 % Description of Baseline Concept: The baseline concept is to remove the Bob Jones Trail Bridge (BJTB) during the demo and reconstruction of the new Prado Creek Bridge, store the BJTB onsite, improve the BJTB abutments, and then return the BJTB to its original location (the western abutment will remain as is. The eastern abutment will be relocated, so the BJTB will be in a slightly rotated position compared to existing). Description of Alternative Concept: The alternative concept proposes to remove the Bob Jones Trail Bridge permanently from the project location. This concept would only be considered if the Bob Jones Trail Bridge is required to be removed for the construction of the new bridge. If any of the other concepts under consideration would help to avoid contact with the bridge during the project, then the Bob Jones Trail Bridge can be left in place without impact. Advantages: • Construction Impacts — Improved by simplifying the construction effort and eliminating the bridge storage, foundation improvement, and reinstallation work from the project scope. Additionally removes the bridge from the in -water bridge construction area (3.8 — 4.2) • Long -Term Impacts — Improved by eliminating the bridge from the creek area and enhancing the natural aesthetic (6.6 — 6.8) • Maintainability — Improved by eliminating the bridge from further future maintenance efforts (6.4 — 6.6) Disadvantages: Multi -Modal Operations — Degraded by removing an access point for the Bob Jones Trail (7.8 — 7.6) Discussion: The main benefit of this proposed alternative concept is to reduce the initial cost of the project while simplifying the construction effort. Discussions during the VE study determined that the existing Bob Jones Trail Bridge would be redundant once the new Prado Creek Bridge bicycle facilities are in place. Additionally, it is understood that the future plan for the trail is for it to be routed toward Elks Lane to the northwest Prado Creek Bridge 34 VA Alternatives Page 1022 of 1059 VA ALTERNATIVE 7.0 (AP-1) Remove and do not replace the Bob Jones Trail Bridge of the Prado Creek Bridge, which makes the connection of the trail to the Prado/Higuera intersection via the Bob Jones Trail Bridge less important. The permanent removal of the Bob Jones Trail Bridge is somewhat dependent on the potential impact to the creek flow hydraulics in relation to the new bridge support structure, the RSP, and the soldier pile retaining wall along the slopes. Discussion of Schedule Impacts: Although the permanent removal of the Bob Jones Trail Bridge would provide additional flexibility for the contractor in completing the in -water work for the project, it does not represent a critical path element for the project schedule. Discussion of Risk Impacts: The alternative concept represents a minor reduction to the construction -related project risk as the in -water work will be reduced. The alternative concept represents a reduction of the future operational risk as the bridge will be removed from future maintenance efforts. Baseline Concept Images Image showing the location of the Bob Jones Trail Bridge in relation to the new bridge Prado Creek Bridge 35 VA Alternatives Page 1023 of 1059 VA ALTERNATIVE 7.0 (AP-1) Remove and do not replace the Bob Jones Trail Bridge Baseline Concept Images (cont.) is Image showing the Bob Jones Trail Bridge (looking north from trail toward Prado Road) Assumptions and Calculations: The initial cost assumption of the alternative concept: • Eliminate Bob Jones Trail Bridge relocation from project (bridge storage, abutment upgrade, and reinstallation) • Assumes no impact to the overall project duration A total cost reduction of $150K was applied for the Value Metrics calculation. The funding for this project element is not included in the federal funding package received for the project. Prado Creek Bridge 36 VA Alternatives Page 1024 of 1059 PROJECT INFORMATION Page 1025 of 1059 PROJECT INFORMATION BACKGROUND The City of San Luis Obispo (City), in cooperation with the Federal Highway Administration (FHWA) and the California Department of Transportation (Caltrans), is proposing to replace Bridge No. 49C-0107 on Prado Road over San Luis Obispo Creek, located approximately 190 feet west of the intersection of Prado Road and South Higuera Street in the City of San Luis Obispo. The City of San Luis Obispo is replacing the bridge with a wider structure that will add improvements to provide safe access to drivers, bicyclists, and pedestrians, better accommodate creek flow, and accommodate anticipated traffic for years to come. The project will include multi -modal improvements to South Higuera at both Prado Road and at Elks Lane, which will be installed ahead of this project beginning construction. Planned for construction in 2027, the Prado Road Bridge Widening Project improvements will pave the way for a brighter, bustling southern district of SLO. This project provides the opportunity to plan for using state-of-the-art infrastructure and forward -thinking design. It sets the stage for an even larger future endeavor: the long -planned Prado Road Interchange Project, a critical infrastructure project that will provide a new crossing over US 101 between Madonna Road and Los Osos Valley Road. This project will be primarily funded through both local City and Caltrans' Highway Bridge Program (HBP) funds. PROJECT DESCRIPTION This project would replace the existing bridge with a wider, four -lane bridge with shoulders, additional turn lanes, protected bike lanes, and sidewalks. The existing two-lane Prado Road Bridge over San Luis Obispo Creek is currently structurally deficient and has no bicycle or pedestrian facilities. Traffic studies also indicate that the bridge is not wide enough to accommodate existing and projected future traffic demands. This means that the project will provide a safer, more accessible route for local businesses, residents, commuters, and visitors into the future. During the bridge removal and construction phase, this project will require closure of the bridge and detours will be created. The project will temporarily move and then relocate the existing adjacent Bob Jones Bike Trail Bridge and trailhead statue to a slightly different onsite location. A temporary trail connection will allow continued trail use during the project. The scope of the project design includes the following elements: • Construction of a wider bridge designed to meet vehicular and multi -modal needs into the future • Safety improvements, including shoulders and protected pedestrian/bicycle paths for travel over the bridge and at the S. Higuera intersection Prado Creek Bridge 37 Project Information Page 1026 of 1059 • Increased channel opening under the bridge, which will improve creek flow capacity • Undergrounding of overhead utilities in the project area for safety and aesthetics • Realignment of the Bob Jones Trail Bridge and the existing trailhead statue, "Oh Great Spirit", to accommodate the bridge widening while preserving access to the trail throughout construction • A noise barrier or "sound wall" will also be constructed to reduce noise levels from vehicle traffic, as heard by the adjacent mobile home residential units PROJECT DESIGN EXCEPTIONS At the time of the study, no mandatory or advisory design exceptions were noted. INFORMATION PROVIDED TO THE VA TEAM The following project documents were provided to the VA team for their use during the study: • Initial Study Environmental Checklist Form — City of San Luis Obispo, 2020 • Type Selection Report for Prado Road Bridge over San Luis Obispo Creek— Quincy Engineering, May 2022 • Foundation Report — Caltrans Bridge No. 49CO107 — Yeh and Associates, November 2025 • Technical Specifications for City of San Luis Obispo Prado Road Bridge Widening —Wallace Group, March 2026 PROJECT DRAWINGS The project team provided preliminary project layouts, cross -sections, and renderings for the VA team during the VA study. The project location and the typical cross-section drawings are included in the project report when applicable and are available from the PDT upon request. PROJECT COST ESTIMATE The VA study used the most current cost estimate for the project dated March 25, 2026. This estimate reflects the preferred design option at the time of the study and details the fully supported and escalated project cost at $45,500,000. Prado Creek Bridge 38 Project Information Page 1027 of 1059 PROTECT ANALYSIS Page 1028 of 1059 PROJECT ANALYSIS SUMMARY OF ANALYSIS The following analysis tools were used to study the project: • Key Project Factors • Cost Model • Function Analysis • Value Metrics KEY PROJECT FACTORS The first day of the VA study included meetings with the project stakeholders. The following summarizes key project issues and site visit observations identified during these sessions. Project Issues The following are some of the issues and concerns associated with the project: Project Budget — The total project cost is currently estimated at $45.5M and will tap funding from several sources — including the federal government through Caltrans. A significant amount of the project will be funded by the City of San Luis Obispo. Present Need vs Potential Need —The present design is a full build approach that is scaled to accommodate the upcoming improved interchange with Highway 101 and is expected to provide capacity for the anticipated development and growth to the east of the Higuera Street - Prado Road intersection including a long-term planning connection of Prado to Broad St. The project must balance the present need and the potential need when determining what to include in the current project design, especially regarding which facility elements to fund with this project. It should be noted that coordination with the upcoming Prado Road/Highway 101 interchange project is a priority for the success of this project. Utility Improvement and Relocation — The current design will require maintaining nearly all the existing utilities that run through the intersection and across the current bridge until they can be relocated to their permanent new locations. Overhead utilities will be undergrounded in a joint trench. Additionally, the project will take the opportunity to improve stormwater management along S. Higuera Street. The utility work requires significant coordination with the utility companies and will encompass the majority of the first stage of the project with traffic handling and construction impacts anticipated. Prado Creek Bridge 39 Project Analysis Page 1029 of 1059 Site Visit Observations A virtual site visit was conducted by the VA study team using google maps, etc. in order to visually assess the project's site conditions and to provide context to all project design components. Through this effort and through the use of several project plan sheets, the VA team was able to more fully understand the constraints, challenges, and issues relating to the project. COST MODEL The VA team leader prepared a cost model from the cost estimate presented in the Project Information section of this report. The model is based on the updated project cost estimate, dated March 25, 2026, which was made available during the VA study and is organized to identify major construction element or trade categories, the original estimated costs, and the percent of total project cost for the significant cost items. The cost model and Pareto chart that follows provide a concise perspective of where major cost items reside within the project cost estimate. Cost Model Item Cost % of Total Cumulative % Bridge Structure $14,791,069 45.8 % 45.8 % Pavement Structural Section $9,874,673 30.6 % 76.3 % Utilities - Sewer $1,506,098 4.7 % 81.0 % Utilities - Stormwater $1,504,608 4.7 % 85.7 % Utilities — Water & Recycled Water $1,355,735 4.2 % 89.8 % Utilities - Dry $1,341,276 4.2 % 94.0 % Landscaping $1,061,922 3.3 % 97.3 % Bike TOTAL $877,289 $32,312,670 2.7 % 100.0 % Prado Creek Bridge 40 Project Analysis Page 1030 of 1059 Pareto Chart $16,000,000 100.0% $14,000,000 / 90.0% /♦/ 80.0% $12,000,000 70.0% $10,000,000 60.0% $8,000,000 50.0% $6,000,000 40.0% 30.0% $4,000,000 20.0% $2,000,000 10.0 $0 0.0% v a) v ao v ++ U a, V) f6 3 f0 Q U m LO LO �n v E a v a, w �CLO U N ? J CO Ln Z) N Y a: C a: ro OCost — —Cumulative Percent The cost items included in the estimate include a 10% markup for Mobilization and a 15% markup for Contingency. The $45.5M total project cost estimate used during the VA study for the project baseline includes additional support costs and markups not detailed in the cost estimate provided to the team. Prado Creek Bridge 41 Project Analysis Page 1031 of 1059 FUNCTION ANALYSIS Function analysis was performed, and a Function Analysis System Technique (FAST) diagram was produced, which revealed the key functional relationships for the project. This analysis provided a greater understanding of the total project and how the project's performance, cost, time, and risk characteristics are related to the various functions identified. The FAST diagram arranges the functions in logical order so that when read from left to right, the functions answer the question "How?" If the diagram is read from right to left, the functions answer the questions "Why?" Functions connected with a vertical line are those that happen at the same time as, or are caused by, the function at the top of the column (a "When?" relationship). Function Accomm. Pedestrians Accomm. Vehicles Acquire R/W Connect Roadway Control Access Control Traffic Convey Water Coordinate Projects Coordinate Stakeholders Collect Water Enhance Aesthetics Establish Vegetation Improve Maintenance Improve Mobility Improve Safety Improve Service (LOS) Increase Lifespan Random Function Identification Function Inform Public Investigate Conditions Maintain Budget Maintain Habitat Maintain Operations Maintain Recreation Maintain Schedule Maintain Services Maintain Standards Maintain Utilities Manage Risk Mitigate Impacts Obtain Funding Obtain Permits Protect Bridge Protect Environment Protect Foundations Function Protect Wildlife Provide Access Relocate Utilities Remove Existing Remove Water Resist Erosion Resist Fire Resist Scour Resist Weather Retain Earth Separate Traffic Span Distance Stage Construction Store Equipment Store Materials Support Load The study team concluded that the higher -order function of the project is to Improve Mobility through the basic functions of Span Distance, Improve Maintenance, Match Existing, and Improve Safety. Key secondary functions include Connect Roadway, Accommodate Vehicles, Accommodate Pedestrians, Accommodate Bicycles, and Support Load. Essential requirements include Maintain Operations, Maintain Access, Protect Environment, Meet Budget, Meet Schedule, Meet Standards, and Reduce Risk. Prado Creek Bridge 42 Project Analysis Page 1032 of 1059 VALUE METRICS Value Metrics provides a systematic and structured means of considering the relationship of a project's performance, cost, time (schedule), and risk as they relate to value. Project performance must be properly defined and agreed upon by the stakeholders at the beginning of the VA study. The basic equation for value is: Value = Perforiiiance Cost + Tirrze The performance attributes and requirements developed are then used throughout the study to identify, evaluate, and document changes to performance and value. OptionLab° was used to facilitate the Value Metrics portions of the VA Study. The following pages describe the steps in the Value Metrics process. Define Performance Requirements Performance requirements represent essential, non -discretionary aspects of project performance. Any concept that fails to meet the project's performance requirements, regardless of whether it was developed during the project's design process or during the VA study, cannot be considered as a viable solution. Concepts that do not meet a performance requirement cannot be considered further unless such shortcomings are addressed through the VA study process in the form of VA alternatives. It should be noted that in some cases, a performance requirement may also represent the minimum acceptable level of a performance attribute. The following performance requirements were selected for this project. Performance Requirement Definition Highway Design Any deviation from the Caltrans' Highway Design Manual must be Standards approvable by the District's Design Reviewer. Structural Design Any structure on the project must comply with current seismic design Standards standards and meet the Load Resistance Design Factor. Environmental Review Any concept or design modification considered must comply with state Process and federal environmental law and be compatible with the environmental review process. Several critical schedule milestones must be met in order to meet legislative and/or funding requirements, these include R/W Project Milestones Certification September 2026; RTL — Early 2027; Award —Spring 2027; Begin Construction — September 2027; End Construction —July 2029. Prado Creek Bridge 43 Project Analysis Page 1033 of 1059 Define Performance Attributes and Scales The Project Development Team (PDT) identified several performance attributes that represent those aspects of a project's scope that possess a range of potential acceptable values. A standard numeric scale is used for each attribute ranging from 1 to 10 where (Minimum Acceptable = 1) to an ideal level of performance (Ideal = 10). The following performance attributes were selected for this project. Rating Label Description 8-10 Ideal 6-8 High 4-6 Medium 2-4 Low Minimum 0 2 Acceptable Multi -Modal Operations The highest reasonable level of performance is achieved. A high level of performance is achieved. A medium level of performance is achieved. A low level of performance is achieved. The minimum acceptable level of performance is achieved. The degree to which the project is contributing to the overall connectivity of the transportation network and access to modal options. Enhancements in multi -modal connectivity should correlate to reductions in greenhouse gases (GHGs) and vehicle miles traveled (VMTs). Possible sub -attributes that may be considered include bicycles, pedestrians, and transit. Long -Term Impacts These are impacts to the environment that extends beyond the completion of construction. This category includes multiple different types of environmental considerations such as ecological (both air and water quality); biological (both animals and plants); cultural (such as parks, historical buildings, and other resources related to the built environment); archaeological (sites and resources that could be disturbed); visual; noise; equity; and economic impacts. Construction Impacts These are impacts to the environment that encompasses the construction time up through the completion of construction. This category includes multiple different types of short-term environmental and construction impacts such as ecological (both air and water quality); biological (both animal and plant); cultural (such as parks, historical buildings and other resources related to the built environment), archaeological (sites and resources that could be disturbed); visual, noise (including vibration and dust); equity, economic, and interim traffic operations. Prado Creek Bridge 44 Project Analysis Page 1034 of 1059 Maintainability The impact to long-term maintenance and operations of the infrastructure. This attribute is focused on life -cycle costs and maintenance access considerations. Maintainability may also consider the resiliency of the infrastructure which includes design and service life in the face of uncertainty. This category encompasses items such as long-term maintenance costs; energy costs related to lighting and technology; maintenance access; service and design life; preservation of critical lifelines; and resiliency of the infrastructure to climate change, seismic events, forest fires, drought, sea -level rise, and surface drainage. Traffic Operations This category considers the degree to which the project improves or degrades traffic operations and conforms to design standards on the transportation system. Included are items such as mainline operations (traffic movement on mainline facilities and/or specific ramp or weaving movement) and local operations (traffic movement on specific local arterials and streets). Prioritize Performance Attributes Once the performance attributes were defined and their scales developed, the PDT and stakeholders prioritized them based on their relative importance to the project using OptionLab°. The performance attributes were systematically compared to each other using the software. Participants were then asked to indicate their priorities and the relative intensities of their preferences. The chart below provides the results of this analysis and includes the complete breakdown of the priorities, expressed as a percentage of the whole. Maintainability Long -Term Impacts Construction Impacts Multi -Modal Operations Traffic Operations Performance Attributes Prioritization 16% 16% 13% 0% 5% 10% 15% 26% 29% 20% 25% 30% 35% Prado Creek Bridge 45 Project Analysis Page 1035 of 1059 Measure Performance of Baseline Concept The PDT and stakeholders evaluated the performance of the baseline concept relative to the performance attribute definitions and scales previously identified. The information below reflects the performance ratings and associated rationale for each attribute. Multi -Modal Operations Rating: 7.8 Rating Rationale: Very Good —The completed facility offers considerable improvements to bicycle and pedestrian connectivity on Prado Road and Higuera Street. All facilities have excellent space and buffers provided with extensive pavement markings along the route, as well as at the Prado/ Higuera intersection. The project will maintain and improve access to the Bob Jones Trail while also enhancing connections to other San Luis Obispo areas, both current and future. Long -Term Environmental Impacts Rating: 6.6 Rating Rationale: Good —The project will replace the existing bridge with a larger structure while seeking to minimize the impacts to the Prado Creek waterway. Additional mitigation efforts are planned to return the creek habitat to its natural state after the in -water work has been completed. Construction Impacts Rating: 3.8 Rating Rationale: Fair —The project is anticipated to have a 3-season construction duration going from September 2027 to July 2029. The project has been broken into 5 logical construction stages. The first stage will focus on utility relocation and stages 3-4 will concentrate on the bridge structure, with stage 3 accomplishing the in -water work. Stages 3-4 will require the closure of Prado Road, and the other stages will maintain operations with traffic handling required. The impacts of the construction effort on the local community and local traffic is expected to be include significant noise, dust, and traffic disruption, but these issues are nearly impossible to avoid. Traffic Operations Rating: 7.7 Rating Rationale: Very Good —The project is expected to provide a high level of future traffic capacity for the Prado Creek Bridge, as well as Higuera Street and the intersection of the two roadway facilities. Several features will be included to provide for all anticipated traffic movements and excellent space has been included for safe interaction with pedestrian and bicycle traffic flows. Maintainability Rating: 6.4 Rating Rationale: Good — The project should provide high quality facility elements with good access for future maintenance needs. The project design is expected to responsibly reduce future LCC demands for the city regarding the bridge, utilities, and the two roadway facilities. Prado Creek Bridge 46 Project Analysis Page 1036 of 1059 Measure Performance of VA Alternatives The VA team prepared performance assessments of each of the VA alternatives during the Development Phase of the VA study. For each VA alternative, the VA team rated its performance using the previously defined scale for each performance attribute. The rationale for any change in performance as compared to the baseline concept was recorded. Please refer to the individual performance assessments for each VA alternative as presented in the VA Alternatives section of this report. Define VA Strategies The VA team identified two VA strategies for consideration. The developed VA Strategies reflect the combination of complimentary VA alternatives recommended by the team and are summarized in the table below. Summary of VA Strategies Strategy Description Initial Cost Savings Change in Schedule Performance Change Value Change VA Strategy 1— Narrow Bridge Only/ 2-week Minimum Build $3,000,000 - 3.5 % + 1.3 reduction Alternative 1.0 VA Strategy 2 — Maximum Savings 2-week Alternatives 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 & $6,070,000 - 2.1 % + 8.0 reduction 7.0 Compare Performance — Baseline Concept and VA Strategies The VA team considered the combined effect of all VA alternatives for the Recommended VA Strategy. The total performance scores reflect the performance rating for each attribute multiplied by its overall priority (weight) expressed using a ration scale. A total performance score of "1" would indicate the highest level of desired performance (i.e., "ideal" performance). The chart below compares the total performance scores for the baseline concept and the VA strategy. Comparison of Performance VA Strategy #2 M VA Strategy #1 Baseline Concept - 0 1 2 3 4 5 6 7 8 9 10 ■ Traffic Operations ■ Multi -Modal Operations ■ Construction Impacts Long -Term Impacts ■ Maintainability Prado Creek Bridge 47 Project Analysis Page 1037 of 1059 Rating Rationale for VA Strategy 1 (Alternative 1.0) The rating rationale for the performance of the baseline concept was presented previously in this section. The rating rationale for the First VA strategy developed by the VA team is provided below. Multi -Modal Operations Rating: 7.0 Rating Rationale: Good to Very Good 1.0 — Improved by reduced distance/wait times for pedestrian crossings at intersection. Degraded by reduction in capacity and losing buffer from traffic. (7.8 — 7.0) Long -Term Environmental Impacts Rating: 7.0 Rating Rationale: Good to Very Good 1.0 — Degraded by constraining future growth in the near term. Improved aesthetic by reducing overall scale of bridge. (6.6 — 7.0) Construction Impacts Rating: 5.0 Rating Rationale: Average 1.0 — Degraded by keeping the Bob Jones Trail Bridge constraining structure work. Improved by reduction in bridge structure and roadway construction. Eliminates need to relocate Bob Jones Trail Bridge. Assume schedule reduction of 2 weeks. (3.8 — 5.0) Traffic Operations Rating: 6.5 Rating Rationale: Good 1.0 — Improved by reduced wait times at intersection. Degraded by reduction in capacity and flexibility for future traffic volume growth. (7.7 — 6.5) Maintainability Rating: 7.0 Rating Rationale: Good to Very Good 1.0 — Degraded by reducing space for performing future maintenance. Improved by reducing size and number of assets to maintain in future. Less stormwater volume. (6.4 — 7.0) Prado Creek Bridge 48 Project Analysis Page 1038 of 1059 Rating Rationale for VA Strategy 2 (Alternatives 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 & 7.0) The rating rationale for the Second VA strategy developed by the VA team is provided below. Multi -Modal Operations Rating: 6.7 Rating Rationale: Good 1.0 - Improved by reduced distance/wait times for pedestrian crossings at intersection. Degraded by reduction in capacity and losing buffer from traffic. (7.8 - 7.0) 2.0 - Degraded by maintaining poles, which will impede the pedestrian and bicycle travel area. (7.8 - 7.7) 7.0 - Degraded by removing an access point for the Bob Jones Trail. (7.8 - 7.6) Long -Term Environmental Impacts Rating: 7.2 Rating Rationale: Good to Very Good 1.0 - Degraded by constraining future growth in the near term. Improved aesthetic by reducing overall scale of bridge. (6.6 - 7.0) 2.0 - Degrades the local aesthetics by maintaining poles and overhead lines. (6.6 - 6.5) 5.0 - Improved by potentially improve or maintain hydraulic flow under the bridge and environmental disturbance impacts and enhanced aesthetics. (6.6 - 6.7) 7.0 - Improved by eliminating the bridge from the creek area and enhancing the natural aesthetic. (6.6 - 6.8) Construction Impacts Rating: 5.9 Rating Rationale: Good 1.0 - Degraded by keeping the Bob Jones Trail Bridge constraining structure work. Improved by reduction in bridge structure and roadway construction. Eliminates need to relocate Bob Jones Trail Bridge. Assume schedule reduction of 2 weeks. (3.8 - 5.0) 2.0 - Degraded by impeding the use of cranes during construction. Improved by removing the undergrounding component of the electrical and some of the fiber utility work from the project. The size of the joint trench can be reduced, and this reduces utility coordination. (3.8 - 3.9) 3.0 - Improved by reducing trenching and shoring required by the contractor. (3.8 - 3.9) 4.0 - Improved by reducing the amount of trenching and shoring required and providing additional utility work flexibility for the contractor in Stage 1. (3.8 - 3.9) 5.0 - Improved by simplifying the construction process of the retaining wall. There would be fewer steps. This removes some of the horizontal lagging and results in less overall work for contractor. (3.8 -4.0) 6.0 - Improved by reduction in raised median construction. (3.8 - Push) Prado Creek Bridge 49 Project Analysis Page 1039 of 1059 7.0 - Improved by simplifying the construction effort by eliminating the bridge storage, foundation improvement, and reinstallation work from the project scope. Additionally removes the bridge from the in -water bridge construction area. (3.8 - 4.2) Traffic Operations Rating: 6.6 Rating Rationale: Good 1.0 - Improved by reduced wait times at intersection. Degraded by reduction in capacity and flexibility for future traffic volume growth. (7.7 - 6.5) 6.0 - Improved by providing additional movement flexibility. (7.7 - 7.8) Maintainability Rating: 7.0 Rating Rationale: Good to Very good 1.0 - Degraded by reducing space for performing future maintenance. Improved by reducing size and number of assets to maintain in future. Less stormwater volume. (6.4 - 7.0) 2.0 - Degraded by maintaining maintenance of overhead utilities into the future and additional potential for damage to these overhead utilities. (6.4 - 6.3) 3.0 - Improved by shallower depth if repairs needed. (6.4 - 6.4 push) 4.0 - Degraded by increasing the amount of maintenance work on existing (older) utilities, as well as disruptions in future years to traffic and community for deferred utility work (6.4 - 6.2) 5.0 - Degraded by more frequent maintenance effort. Improved by being easier to maintain the RSP than the retaining wall. (6.4 - 6.5) 6.0 - Improved by reduced raised median to maintain. (6.4 - push) 7.0 - Improved by eliminating the bridge from further future maintenance efforts. (6.4 - 6.6) Compare Value The cost and time (i.e., schedule) elements were compared and prioritized by the project decision makers. The relative importance of cost and time is shown on the following table. These factors were applied to the cost and time scores and incorporated into the value calculations. Relative Importance COST 65 % TIME 35 % Once relative scores for performance, cost, and time have been derived, the next step is to synthesize a value index for the baseline concept and each VA strategy. This is achieved by applying the following algorithm for value: Prado Creek Bridge 50 Project Analysis Page 1040 of 1059 • V = Value • P = Performance • t = Time • f = Function • C = Cost • a = Risk En 1Pn - a Vf (P, C, t)total _ — En l[(Cn - a) + (tn - a)] A Value Matrix was prepared which facilitated the comparison of competing strategies by organizing and summarizing this data into a tabular format. The performance scores for each strategy were divided by the total cost/time scores for each strategy to derive a value index. The value indices for the VA strategy are then compared against the value index of the baseline concept and the difference is expressed as a percent (±%) deviation. 10 9 8 7 6 5 4 3 2 1 0 Comparison of Value Baseline Concept and VA Strategies C 8.1 Baseline Concept VA Strategy #1 VA Strategy #2 Perf. Cost � Time —•—Value % A 100 % 90% 80 % 70% 60 % 50% 40% 30% 20% 10% 0% Prado Creek Bridge 51 Project Analysis Page 1041 of 1059 IDEA EVALUATION Page 1042 of 1059 IDEA EVALUATION The ideas generated by the VA team were carefully evaluated, and project -specific attributes were applied to each idea to assure an objective evaluation. PERFORMANCE ATTRIBUTES The following are key performance attributes identified for this project and used to assist the VA team in evaluating the ideas: • Multi -Modal Connectivity • Traffic Operations • Long -Term Impacts • Maintainability • Construction Impacts The VA team enlisted the assistance of the stakeholders and project team (when available) to develop these attributes so that the evaluation would reflect their specific requirements. EVALUATION PROCESS The VA team generated and evaluated ideas on how to perform the various project functions using other approaches. The idea list was grouped by function or major project element. Each idea was evaluated with respect to the functional requirements of the project. Performance, cost, time, and risk may also have been considered during this evaluation. Once each idea was fully evaluated, it was rated to determine which ideas had the greatest potential for value improvement. Ideas identified for development as VA alternatives or as other considerations are documented in the VA Alternatives section of this report. IDEA SUMMARY All the ideas generated during the Creativity Phase using brainstorming techniques are recorded on the following pages. The team created and evaluated these ideas together using Miro. Each idea received an idea code based on the function statement under which it was brainstormed. The following table indicates the functions related to each idea code. Idea Code Related Function AB AP Accomm. Bicycles Accomm. Pedestrians CR Connect Roadway CT Control Traffic CP Coordinate Projects EA Enhance Aesthetics Idea Code Related Function MU MS Maintain Utilities Manage Schedule RE Retain Earth SD Span Distance SL Support Load Prado Creek Bridge 52 Idea Evaluation Page 1043 of 1059 IDEA SUMMARY LIST Code Function/Idea Description Rating Accommodate Bicycles AB-1 Use Class I in lieu of protected bike lane (Class IV) on south side of Prado COM AB-2 Use sidewalk and shoulder in lieu of Class IV in north side of Prado COM AB-3 Eliminate bike facilities on Prado east of Higuera COM AB-4 Reduce/remove green pavement markings (possibly include in min build) OC AB-5 Eliminate the protected corner on NW corner of Prado/Higuera DIS AB-6 Reduce size of protected corners at Prado/Higuera ABD AB-7 Provide transition from shoulder to Class I on Prado at Elks (com w/AB-1) COM AB-8 Eliminate western Bob Jones Trail connection DIS AB-9 Remove colored concrete and reduce thickness from Class IV bikeways OC Accommodate Pedestrians AP-1 Do not replace the Bob Jones Bridge DEV Provide temporary fenced corridor through water treatment area to maintain AP-2 DIS Bob Jones Trail access Connect Roadway CR-1 Eliminate second eastbound lane on Prado east of Higuera COM Maintain roadway width but eliminate Southbound Higuera left -turn lane to CR-2 COM eastbound Prado (must go with CR-1) Control Traffic CT-1 Reduce raised median length on west Prado (still need to negate left -turn out DEV movement) Coordinate Projects CP-1 Delay schedule to align construction with interchange project OC CP-2 Remove Higuera pavement portion from project (shift to future South Higuera DIS project) Prado Creek Bridge 53 Idea Evaluation Page 1044 of 1059 Enhance Aesthetics EA-1 Reduce architectural treatments on bridge OC Maintain Utilities MU-1 Use the Bob Jones Bridge for relocation of utilities (sewer & recycled water) DIS MU-2 Remove undergrounding of overhead utilities from project DEV MU-3 Reduce depth of cover of joint trench from 7' to 3' DEV Maintain temporary utilities on the stream diversion in lieu of temporary bridge - MU-4 combine with removal of retaining wall COM Reduce utilities to be replaced to just on bridge (do not address utilities on MU-5 Higuera — defer to later project) DEV MU-6 Use a wider joint trench in lieu of a deeper joint trench DIS MU-7 Bury sewer line under creek in lieu of routing along bridge DIS Eliminate temporary utility bridge by supporting existing sewer at R/W lines in MU-8 place DEV MU-9 Eliminate reconnecting potable water main post -construction DIS Manage Schedule MS-1 Extend in -water work window (earlier and later) ABD Retain Earth RE-1 Reduce length of retaining wall — outside of bridge (hydraulics question) DEV RE-2 Reduce retaining wall — underneath the bridge (hydraulics question) DEV Use rock -slope protection in lieu of retaining wall under bridge — combine with RE-3 COM RE-2 Use tangent pile wall in lieu of soldier pile wall outside of bridge — combine with RE-4 DEV RE-1 Span Distance SD-1 Reduce width of bridge by eliminating one lane (eastbound through) DEV Reduce width of bridge by consolidating pedestrian and bicycle lanes on south SD-2 COM side SD-3 Reduce width of ridge on north side by eliminating protected bike lane COI SD-4 Reduce width of bridge by minimizing width of median DIS Prado Creek Bridge 54 Idea Evaluation Page 1045 of 1059 Enhance Aesthetics SD-S Reduce width of bridge by reducing lanes from 12' to 11' COM Support Load SL-1 Reduce depth of all girders DIS SL-2 Reduce depth of some of the girders DIS SL-3 Eliminate all girders DIS Leave existing buried PCC section at Prado/Higuera intersection and pave with SL-4 DIS HMA SL-S Construct a cast -in -place bridge in lieu of precast bridge DIS SL-6 Use sub -grade stabilization in lieu of full depth reclamation cement (FDRC) DEV DEV: Combine with other VA Alternative idea OC: Other Consideration ABD: Already Being Done (in the Baseline Concept) DIS: Dismissed COM: Combine Prado Creek Bridge 55 Idea Evaluation Page 1046 of 1059 VA PROCESS Page 1047 of 1059 LTIA a ' el"I0 The Value Analysis (VA) process used for this study borrows heavily from the VA process developed in partnership with the California Department of Transportation (Caltrans) over the last 30+ years. The process involves 16 activities needed to accomplish a VE study, and is organized into three parts: Pre - Study, VA Study, and Report. Integral to Caltrans' VA process is the Value Metrics. Value Metrics provides a systematic and structured means of considering the relationship of a project's performance, cost, time (schedule), and risk as they relate to value. Project performance must be properly defined and agreed upon by the stakeholders at the beginning of the VA study. The performance attributes and requirements developed are then used throughout the study to identify, evaluate, and document changes to performance and value. OptionLab° was used to facilitate the Value Metrics portions of the VA Study. The following provides an overview of the Caltrans approach to VA. The Caltrans VA Study Activity Chart at the end of this narrative identifies the steps in each activity, which are detailed as follows. PRE -STUDY Meaningful and measurable results are directly related to the pre -study work performed. Depending on the type of study, all or part of the following information needs to be determined during the pre - study phase: • Clear definition of the current situation and study objectives • Identification of study team members • Identification of project stakeholders • Definition of how stakeholders are impacted by the project • Identification of key issues and concerns • Identification of project's performance requirements and attributes • Status of project cost estimate • Project data gathered to be distributed to VA team In preparation for the VA study, the team leader confers with owners and stakeholders to outline the VA process; initiate data gathering; refine project scope and objectives; structure the scope, team members, and technical specialists; and finalize study plans. Specific deliverables are provided. Following the initial planning meeting, the team leader reviews the data collected for the project and develops a cost model. The team leader also consults with the technical specialists to prepare them for the VA study. Prodo Creek Bridge 56 VA Process Page 1048 of 1059 VA STUDY This VA study was conducted in a virtual environment using MS Teams. MS Teams is a virtual meeting platform that supports audiovisual communications and facilitates the use of breakout sessions to allow for multiple, parallel meetings. The VA Job Plan guides the VA team in their search to enhance value in the project or process. Caltrans follows a seven -phase VA Job Plan: 1. Information Phase 2. Function Analysis Phase 3. Creativity Phase 4. Evaluation Phase 5. Development Phase 6. Presentation Phase 7. Implementation Phase Information Phase At the beginning of the VA study, the design team presents a more detailed review of the design and the various systems. This includes an overview of the project and its various requirements, which further enhances the VA team's knowledge and understanding of the project. The project team also responds to questions posed by the VA team. The project's performance requirements and attributes are discussed, and the performance of the baseline concept is evaluated. Function Analysis Phase Key to the VA process are the function analysis techniques used during the Function Analysis Phase. These techniques may include but are not limited to: • Random Function Identification • Function -Resource Allocation • Function Analysis System Technique (FAST Diagrams) • Graphic Function Identification Analyzing the functions of a project is essential to assuring an owner that the project has been designed to meet the stated criteria and its need and purpose. The analysis of these functions in terms of cost, performance, time, and risk is a primary focus in a VA study and is used to identify areas within a project for value improvement. This procedure is beneficial to the VA team, as it forces the participants to think in terms of functions and their relative value in meeting the project's need and purpose. This facilitates a deeper understanding of the project. Creativity Phase The Creativity Phase involves identifying and listing creative ideas. During this phase, the VA team participates in a brainstorming session to identify as many means as possible to provide the necessary project functions. The judgement of the ideas is not permitted in order to generate a broad Prodo Creek Bridge 57 VA Process Page 1049 of 1059 range of ideas. The idea list includes all of the ideas suggested during the study. These ideas should be reviewed further by the project team since they may contain ideas worthy of further evaluation and may be used as the design develops. These ideas could also help stimulate additional ideas by others. Evaluation Phase The purpose of the Evaluation Phase is to systematically assess the potential impacts of ideas generated during the Creativity Phase relative to their potential for value improvement. Each idea is evaluated in terms of its potential impact to performance, cost, time, and risk. Once each idea is fully evaluated, it is classified as an idea to either "Develop" or "Dismiss." Some ideas can also be "Combined" with other promising ideas or ideas which are "Already Being Done." The rationale for why ideas were rated highly but not developed as alternatives is documented in the Idea Evaluation section of the report. Development Phase During the Development Phase, the highly rated ideas are expanded and developed into VA alternatives. The development process considers the impact to performance, cost, time, and risk of the alternative concepts relative to the baseline concept. This analysis is prepared as appropriate for each alternative, and the information may include a performance assessment, initial cost and life - cycle cost comparisons, schedule analysis, and an assessment of risk. Each alternative describes the baseline concept and proposed changes and includes a technical discussion. Sketches and calculations are also prepared for each alternative as appropriate. Presentation Phase The VA study concludes with a preliminary presentation of the VA team's assessment of the project and VA alternatives. The presentation provides an opportunity for the owner, project team, and stakeholders to preview the alternatives and develop an understanding of the rationale behind them. Implementation Phase After the stakeholders have had an opportunity to review the alternatives identified by the VA team, the team leader conducts an implementation meeting to discuss the alternatives and resolve appropriate action for each VA alternative. If necessary, any other VA report edits requested by the representatives are also made by the VA team leader and a final report is issued. This implementation meeting helps to ensure that savings or process improvements are not lost due to a lack of communication, and that those VA alternatives that are accepted are properly integrated into the project design. VA REPORT Preliminary Report: Following the completion of the VA study, the team leader compiles the information developed during the VA study into the Preliminary Value Analysis Study Report. This Prado Creek Bridge 58 VA Process Page 1050 of 1059 report, documenting viable alternatives, is provided to the customer within the timeframe requested (usually within two weeks of study completion). The preliminary report also contains a VA Study Summary Report — Preliminary Findings, designed to highlight critical elements of the VA study, including detailed documentation of VA alternatives, in a concise manner for the use of parties without the opportunity to review the report in its entirety. More details can be found in the complete preliminary report, which consists of the following documentation: Executive Summary, VA Alternatives, Project Information, Project Analysis, Idea Evaluation, and VA Process. Final Report: once all VA alternatives have been either accepted or rejected, the team leader updates the Preliminary Value Analysis Study Report to show the final results of the study in a Final Value Analysis Study Report. In addition, a Value Analysis Study Summary Report (VASSR) is sent to Caltrans HQ to permit easy documentation into the Caltrans Annual Report to FHWA. The following Caltrans VA Study Activity Chart describes each activity. Prado Creek Bridge 59 VA Process Page 1051 of 1059 CALTRANS VA STUDY ACTIVITY CHART INITIATE STUDY ORGANIZE STUDY PREPARE DATA ➢ Identify study project ➢ Conduct Pre -Study Meeting ➢ Collect and distribute data ➢ Identify study roles and ➢ Select team members ➢ Develop construction cost responsibilities ➢ Identify stakeholders, models ➢ Define study goals decision -makers, and ➢ Develop highway user ➢ Select team leader technical reviewers benefit/life-cycle cost (LCC) ➢ Prepare draft Study Charter ➢ Identify data collection model (if required) ➢ Select study dates ➢ Determine study logistics ➢ Update VA Study Charter ➢ Identify and define performance requirements 1 2 3 INFORM TEAM ANALYZE FUNCTIONS CREATE IDEAS EVALUATE IDEAS ➢ Review study activities and ➢ Analyze project data ➢ Focus on functions ➢ Apply key confirm reviewers ➢ Expand project functions ➢ List all ideas performance ➢ Present design concept ➢ Prepare FAST diagram ➢ Apply creativity and attributes to rate idea ➢ Present stakeholders' ➢ Determine functional cost innovation techniques ➢ List advantages and interests drivers and performance (group and individual) disadvantages ➢ Review project issues and ➢ Consider cost impacts objectives ➢ Rank all ideas ➢ Rate performance of ➢ Assign alternatives for baseline concept development ➢ Visit project site 4 5 6 7 DEVELOP ALTERANTIVES CRITIQUE ALTERNATIVES I PRESENT ALTERNATIVES I ➢ Develop alternative ➢ VA alternatives technical ➢ Present findings concepts review ➢ Document feedback ➢ Prepare sketches and ➢ VA alternatives team ➢ Confirm pending reviews calculations consensus review i ➢ Prepare preliminary report ➢ Measure performance ➢ Identify mutually exclusive ➢ Estimate costs, LCC groups of alternatives *Interim presentation of study benefits/costs ➢ Identify VA strategies i findings 8 ➢ Validate performance 10 9 ASSESS ALTERNATIVES** RESOLVE ALTERNATIVES I PRESENT RESULTS* ➢ Review Preliminary Report ➢ Review implementation ➢ Present results ➢ Assess alternatives for dispositions ➢ Obtain management project acceptance ➢ Resolve implementation approval on implemented ➢ Prepare draft actions with decision- alternatives implementation makers and stakeholders ➢ Summarize performance, dispositions ➢ Edit alternatives cost, and value **Activities performed by PDT, ➢ Revisit rejected i improvements Technical Reviewers, and alternatives, if needed *Final presentation of study Stakeholders 11 12 results 13 DOCUMENT STUDY ➢ Document process and study findings ➢ Distribute Preliminary VA Report ➢ Distribute electronic report to HQ VA Branch ➢ Conduct Implementation Meeting 14 ------------- VA IMPLEMENTATION ACTION MEMO (If Conditionally Accepted Alternatives exist) ➢ Publish memo to document action plan to complete study ➢ Resolve Conditionally Accepted Alternatives 15 ------------ PUBLISH RESULTS ➢ Document process and study results ➢ Incorporate all comments and implementation actions ➢ Distribute Final VA Report ➢ Distribute electronic report to HQ VA Branch ➢ Update VA Study Summary Report (VASSR) ➢ Provide HQ the Final VA Report in PDF format 16 r-------- Note: The dashed I I I boxes indicate steps that may not be I I I required in some VA studies Prado Creek Bridge 60 VA Process Page 1052 of 1059 Prado Creek Bridge Project VA Study Agenda Day 1 — Monday, March 30`h — 612 Clarion Ct., San Luis Obispo (and virtual via Microsoft Teams) 7:45 8:00 8:15 9:30 11:30 11:45 12:00 1:00 2:00 2:30 4:00 Facilitator Set-up Introductions & Agenda Review Sponsor (PM, Design Team & VA Facilitator) In -Brief • Need & Purpose • Overview of Current Project Status • Study Process • Study Deliverables Discussion on Focused Project Items Discussion of Performance Measures Additional Q/A Lunch Team Review and Discussion of Design Documentation & Estimate Review FAST Analysis Discussion Initial Team Brainstorming Adjourn Day 2 — Tuesday, March 315t — 612 Clarion Ct., San Luis Obispo (and virtual via Microsoft Teams 8:00 Team Set-up & Agenda Review 8:15 Team Brainstorming (cont.) 9:30 Team Evaluation of VA Ideas 10:30 Team Development of VA Alternatives Value = 11:30 Lunch 12:30 Team Development of VA Alternatives (cont.) 4:00 Adjourn Day 3 — Thursday, April 2"d — virtual Via Microsoft Teams 8:00 Team Set-up & Agenda Review 8:15 Team Development of VA Alternatives (cont.) 10:30 Finalization of VA Alternatives 11:00 Determine and Score Team Recommended VA Strategy 11:30 Lunch 12:30 Design Suggestion Finalization & VA Study Presentation Preparation 1:00 Presentation of Initial VA Study Results (Team Recommended VA Strategy) 3:00 Adjourn Performance Cost + Time WALLACE GROUP 61 VMS+ Value Management Strategies, Inc. Page 1053 of 1059 V) W W 0 W z N W G1 O Q � N V m CL z te a 06 LLI L W V M O o M � � L 0 L U F E W v ru i _. X x x cu L - L c .� c 0A Q bA W w u u a w m a n a 0 0 /n rrL^^ //Ln� V V V U U U >3 N 2 I C O N C U oc C H O H C U C CO C J c Al m C 0 E U C O Y E c t O O Q N O O M L Ep O O `O L E a, C L Y � � m � C o2S a) pq � W a1 u m U c L N + \ O n3 J wu O � \ pA m m O v L U U m U EF E C O a U ' m m U -6 C U N C U F- L m h L O (0 C7 U U U a 0 H c JI W c 0 0 0 0 a to V) In N o2S C Q- O O O O> L U U �+ >- LL U U U U U U C 0 O N (6 C N aJ L O = 0 N z i u c N L m 7 U- N t Y c .cA N y CCv G CC� G m J ccCiD G c > x x X ao U � X x x i o .v a i O � o a > x x x x i O � O_ x � � m Lo 0 v� U o O � C�- Ln j O Q) 0) /gym LL Qi RESOLUTION NO. (2026 SERIES) A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF SAN LUIS OBISPO, CALIFORNIA, AUTHORIZING BUDGET ADJUSTMENTS FOR THE PRADO CREEK BRIDGE REPLACEMENT PROJECT WHEREAS, the Prado Creek Bridge Replacement Project (Bridge Project) will replace the structurally deficient Prado Road bridge over San Luis Obispo Creek and improve the Prado Road and South Higuera Street intersection, multimodal access, safety, and utility reliability; and WHEREAS, the Bridge Project budget currently includes $4,130,000 in Federal Earmark Funds, although the maximum authorized reimbursement is $2,065,000; and WHEREAS, the Bridge Project budget currently includes $6,000,000 in Highway Bridge Program Funds that are not yet authorized for expenditure; and WHEREAS, the estimated Highway Bridge Program funding for the Bridge Project is currently $13,861,673, and the correct amount will be appropriated when those grant funds are authorized for expenditure; and WHEREAS, these budget adjustments will align the projects' funding sources and grant appropriations with current reimbursement authorizations without increasing the total approved project budgets; and NOW, THEREFORE, BE IT RESOLVED by the Council of the City of San Luis Obispo as follows: SECTION 1: Environmental Review. The funding actions authorized by this resolution are not subject to environmental review under the California Environmental Quality Act because they are not a project, as defined by State CEQA Guidelines Section 15378, and do not commit the City to any change in the previously approved projects. SECTION 2: Grant Budget Adjustments. The City Council authorizes the Finance Director, or designee, to: 1. Decrease the Federal Earmark Fund appropriation for the Prado Creek Bridge Replacement Project from $4,130,000 to $2,065,000 to correct a duplicated appropriation and align the project budget with the maximum authorized grant reimbursement. 2. Decrease the Highway Bridge Program Fund appropriation for the Prado Creek Bridge Replacement Project from $6,000,000 to $0 because the funds are not currently authorized for expenditure. The correct grant amount will be appropriated when the funds are authorized for expenditure. R Page 1055 of 1059 Resolution No. (2026 Series) Page 2 SECTION 3: Administrative Authority. The Finance Director, or designee, is authorized to make the accounting entries and other administrative adjustments necessary to implement this resolution. Upon motion of seconded by , and on the following roll call vote: AYES: NOES: ABSENT: The foregoing resolution was adopted this day of Mayor Erica A. Stewart ATTEST: Teresa Purrington City Clerk APPROVED AS TO FORM: KIWI*] J. Christine Dietrick City Attorney IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the City of San Luis Obispo, California, on Teresa Purrington City Clerk 0 Page 1056 of 1059 RESOLUTION NO. (2026 SERIES) A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF SAN LUIS OBISPO, CALIFORNIA, AUTHORIZING SUBMITTAL OF GRANT APPLICATIONS FOR THE PRADO ROAD INTERCHANGE PROJECT AND PRADO CREEK BRIDGE REPLACEMENT PROJECT, AND REQUIRING COUNCIL APPROPRIATION UPON GRANT AWARD WHEREAS, the Prado Road Interchange Project will construct a new Prado Road overcrossing of US 101, reconstruct the northbound interchange ramps, add a northbound auxiliary lane between Prado Road and Madonna Road, realign Elks Lane, and widen Prado Road; and WHEREAS, the Prado Creek Bridge Replacement Project will replace the structurally deficient Prado Road bridge over San Luis Obispo Creek and improve the Prado Road and South Higuera Street intersection, multimodal access, safety, and utility reliability; and WHEREAS, the Prado Road Interchange Project and Prado Creek Bridge Replacement Project are significant transportation capital improvement projects that advance City mobility, safety, infrastructure resilience, and long-term community development objectives; and WHEREAS, the City Financial Management Manual Grant Management Policy provides that the City will actively pursue federal, state, and other grant funding consistent with identified City goals and objectives, particularly for capital improvements; and WHEREAS, the Grant Management Policy requires City Council approval of grant applications in excess of $5,000 and allows the Council to delegate receipt of grant funds and execution of related grant documents to the City Manager when permitted by the granting agency; and WHEREAS, grant opportunities may become available that could provide funding for either or both the Prado Road Interchange Project and Prado Creek Bridge Replacement Project; and WHEREAS, the City Council desires to authorize staff to pursue and submit eligible grant applications while retaining Council authority to appropriate awarded grant revenues, approve any required local match, and authorize expenditures before grant - funded work proceeds. NOW, THEREFORE, BE IT RESOLVED by the Council of the City of San Luis Obispo as follows: SECTION 1: Environmental Review. The authorization to prepare and submit grant applications is an administrative and fiscal action that does not authorize construction, commit the City to a physical change in the environment, or alter the scope of either R Page 1057 of 1059 Resolution No. (2026 Series) Page 2 project. Accordingly, this resolution is not a project subject to environmental review under the California Environmental Quality Act, pursuant to State CEQA Guidelines Section 15378. SECTION 2: Authorization to Submit Grant Applications. The City Council authorizes the City Manager, or designee, to identify eligible local, state, federal, and other grant opportunities and to prepare and submit grant applications for the Prado Road Interchange Project, the Prado Creek Bridge Replacement Project, or both projects, provided that each application is consistent with the applicable project scope, City plans and policies, and grant program requirements. SECTION 3: Application Documents and Certifications. The City Manager, or designee, is authorized to execute grant application forms, certifications, and other documents required to submit an application, provided that doing so does not accept a grant award, appropriate funds, commit the City to an unbudgeted expenditure, or obligate the City to provide a local match that has not been approved by the City Council. SECTION 4: Grant Award and Appropriation. If grant funding is awarded for either project, staff shall return to the City Council, as applicable, with a recommendation to accept the grant award, appropriate grant revenues and any required local matching funds, authorize any necessary budget amendments, and request authority to execute grant agreements or other award documents. No grant funds may be expended and no required local match may be committed unless and until the City Council takes the necessary appropriation and authorization actions. SECTION 5: Administrative Authority. The Finance Director, or designee, is authorized to make the accounting entries and other administrative adjustments necessary to implement this resolution after the City Council has approved the applicable grant acceptance and appropriation actions. Upon motion of , and on the following roll call vote: AYES: NOES: ABSENT- The foregoing resolution was adopted this day of ATTEST: seconded by Mayor Erica A. Stewart fl 2026. Page 1058 of 1059 Resolution No. (2026 Series) Page 3 Teresa Purrington City Clerk APPROVED AS TO FORM: J. Christine Dietrick City Attorney IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the City of San Luis Obispo, California, on Teresa Purrington City Clerk 0 Page 1059 of 1059 Prado Road Interchange and Prado Creek Bridge Projects August 4, 2026 Agenda Prado Road Interchange Recommendations Introduce a draft Ordinance to establish a New Underground Utility District Receive and file various technical reports Provide direction an Aesthetic Theme for the Interchange Project Provide direction on a future Class I shared-use path along Elks Lane Prado Creek Bridge Recommendations Provide direction on a Value Analysis Authorize budget revisions Prado Creek Bridge & Prado Road Interchange Projects Recommendation Authorize Submittal of future Grant Applications 2 Related Corridor Projects Prado Interchange Prado Bridge Prado Extension Results Multimodal Corridor Address key growth areas such as San Luis Ranch, Margarita, Tank Farm) Improves congestion, safety, and emergency response 3 4 Elks Lane RTA 40 Prado Prado Road US 1 0 1 Corp Yard Project Background - Interchange WRRF, Project Background - Bridge 5 Project Milestones Long-term Prado Road corridor investment Environmental, engineering, funding, and agency c Interchange Project advancing through final design Value Analysis completed for both projects Council direction needed to advance design 6 Underground Utility District 17 7 Requires overhead utilities to be placed underground District No. 16 - Bridge Project Proposed District No. 17 - Interchange Project Provides a framework for utility design, notice, and property coordination Removes conflicts with transportation and landscape improvements Improves safety, reliability, resilience, and gateway appearance Interchange Value Analysis 8 Interchange Cost Update 9 Interchange Aesthetic Themes Three concepts have been developed: the Base, Mission, and Modern Mission themes. All three appear capable of advancing for Caltrans approval, subject to refinement and final review. Components such as wall textures, railings, fencing, landscaping, and lighting may be combined among themes. Council is being asked to identify the preferred overall character and desired architectural components. General direction will allow the project team to refine a coordinated aesthetic design with Caltrans. 10 Interchange Aesthetic Theme - Base 11 Interchange Aesthetic Theme - Mission 12 Interchange Aesthetic Theme – Modern Mission 13 Gateway Identification 14 Bridge Value Analysis Recommendations 15 Coordinated Construction Schedule 16 Elks Lane Class I Shared-Use Path 17 Funding Strategy 18 Grant Strategy 19 Grant program Level Potential Project amount *Solutions for Congested Corridors Program State Approximately $70 million to $85 million *Local Partnership Competitive Program State Up to $25 million *Local Highway Safety Improvement Program Federal $100,000 to $10 million BUILD Federal Approximately $25 million planning target Rural Surface Transportation Grant Federal Approximately $40 million planning target INFRA Federal Approximately $60 million potential award Trade Corridor Enhancement Program State/federal Approximately $16 million realistic Central Coast target Next Steps Implement Council direction Update Bridge plans based on approved Value Analysis recommendations Continue pursuing grant funding Return September 1, 2026, for the ordinance’s second reading Community Meeting & Right of Way considerations in Summer 2027 20 Requested Council Actions - Interchange 1.Introduce a draft Ordinance amending Section 13.12.040 of the San Luis Obispo Municipal Code to Establish a New Underground Utility District 17”; and 2.Receive and file the Final Value Analysis, Draft Bridge Type Selection and Wall Type Selection Reports which provides the technical basis for the Supplemental Project Report and final design development; and 3.Authorize the Assistant City Manager to approve and execute the final Caltrans Supplemental Project Report (SPR) upon completion of the remaining technical appendices, provided no substantive changes are made to the project scope, purpose, or core recommendations; and 4.Select an Aesthetic Theme for the Interchange Project: a) “Figure 4 – Base Theme”; or b) “Figure 5 – Mission Theme”; or c) “Figure 6 – Modern Mission Theme”; and 5.Provide direction on gateway branding by either: a) Including; or b) advancing a more heavily landscaped area instead of City branding; and 6.Direct staff to evaluate a future Class I shared-use path along Elks Lane during the next update to the City's Active Transportation Plan and, where feasible, acquire the necessary right-of-way in conjunction with the Prado Road Interchange Project; and 21 Requested Council Actions - Bridge 7.Receive and file the Preliminary Value Analysis Study (Attachment I) and approve Value Analysis implementing design alternatives 1.0, 3.0, 4.0, 5.0, and 6.0 and not implementing design alternatives 2.0 and 7.0; and 8.Authorize the Finance Director to make the following budget revisions: a.Decrease the project’s appropriation of Federal Earmark grant funds from $4.130 million to $2.065 million to resolve an accounting duplication; and b.Decrease the projects appropriation of Federal Highway Bridge funds from $6.0 million to $0 to more appropriately align the funds with the anticipated reception timeframe; and 9.Adopt a Draft Resolution entitled, “A Resolution of the City Council of the City of San Luis Obispo, California, Authorizing Budget Adjustments for the Prado Creek Bridge Replacement Project.” (Attachment J) 22 Requested Council Actions – Both Projects Prado Creek Bridge & Prado Road Interchange Projects Recommendation 10. Adopt a Draft Resolution entitled, “A Resolution of the City Council of the City of San Luis Obispo, California, Authorizing Submittal of Grant Applications for the Prado Road Interchange Project and Prado Creek Bridge Replacement Project, and requiring Council Appropriation upon Grant Award.” (Attachment K) 23 24Council Questions Segment 1 2 – Travel Lanes 1 – Turn Lane 25 1 – Sidewalk 1 – Shared Use Path 2 – Shoulders Segment 2 4 – Travel Lanes 1 – Turn Lane 26 1 – Sidewalk 1 – Shared Use Path 2 – Shoulders Segment 3 4 – Travel Lanes 1 – Turn Lane 27 1 – Sidewalk 1 – Shared Use Path 2 – Shoulders Bridge Project 28 Bridge Project 29 Value Analysis 30 Cost-saving design alternatives: Reducing overall bridge width Replacing retaining walls with rock slope protection Limiting utility relocations Reducing median width and utility trench depth Removing undergrounding of utilities Eliminating both the removal and replacement of the existing Bob Jones Trail bridge These alternatives could result in up to $6 million in cost savings if implemented collectively. Bridge Width 31 Flyovers 32 Question #1 – Creek Bridge Width Tradeoffs Does the reduced-width bridge concept presented still meet the ATC’s expectation for a safe, continuous, and comfortable east–west bicycle and pedestrian connection through the corridor? 33 Question #2 – Bob Jones Bridge If the existing Bob Jones Trail bridge must be removed to construct the Prado Creek Bridge, does the ATC prefer: A.Reinstalling the bridge in a modified alignment following construction, B.Permanently removing the bridge and relying on the Prado corridor shared-use path and signalized crossings for connectivity 34 Question #3 – Bob Jones Alignment A.Should the project assume that a future Bob Jones Trail alignment north of Prado Road (creek-adjacent alignment consistent with prior ATP concepts) ultimately be pursued? B.Should the project instead assume that a creek-adjacent alignment is unlikely to be implemented in the foreseeable future and prioritize near- term, implementable multimodal connections within the Prado Road corridor and adjacent roadway network? 35 Bridge Project - Aesthetics 36 Bridge Project 37 Grant Appropriation Adjustments Federal Earmark Appropriation The same $2.065 million grant was appropriated in both the 2023-25 and 2025-27 Financial Plans. The recommended action reduces the budgeted amount from $4.130 million to the correct grant maximum of $2.065 million. Highway Bridge Program The second adjustment reduces the current Highway Bridge Program appropriation from $6 million to zero. Approximately $13.861 million remains anticipated for the project and will be appropriated when Caltrans authorizes the applicable funding phase. 38 Technical Reports Technical reports formalize the revised Interchange design Bridge and Wall Type Reports evaluate structural options, constructability, maintenance, and cost Visible structural treatments will match the Council-selected aesthetic theme Supplemental Project Report documents design changes, costs, and schedules Caltrans will revalidate the existing CEQA and NEPA approvals 39