The URL can be used to link to this page

Home My WebLink About_2025-04-25-Doc_Enclave Lot 24_SWCP_v1 (1)Stormwater Control Plan for Post Construction Requirements Exhibit 4 Application Submittal Where directions state “Done” that means no additional information or forms below that point needs to be filled out or furnished. See Exhibits for Watershed Management Zones, Basins, & Urban Sustainability Areas Use “n/a” where information requested is not applicable. If you are unsure regarding how to fill out any of the information, please come in and request assistance from a staff person. Project Information Step 1 Applicant Name: Application No: Project Name: Location Address: Location APN: Site Zoning: Project Type:  Commercial Detached Single Family Residential Industrial Multi-unit Residential Mixed Use Public Project Phase: Project Description: Total Project Site Area = (a) Total New Impervious Surface Area = (b) Total Replaced Impervious Surface Area = (c) Total Existing Impervious Area = (d) Total Impervious Area of Completed Project = (e) Net Impervious Area: (a+b) – (c-d) = OR where (c-d) is a negative number: (a+b) = Your project is NOT subject to Post Construction Requirements if… Step 2  Area (a+b) of project is < 2,500 square feet – Done OR  Area (a+b) of project is > 2,500 square feet, and is a project type listed below ( type) – Done  Road & parking surface repair – slurry & fog & crack seal, pothole & spot patching, overlay & resurfacing & other damage repair with no expansion  Road & parking shoulder grading  Road & parking cleaning, repairing, maintaining, reshaping, regarding drainage systems  Sidewalk & bike path / lane project – no other impervious surface created and runoff is directed to vegetated area  Curb & gutter improvement or replacement – no other impervious created  Underground utility project – surface replaced in kind  Utility vaults – Ex: lift stations, backflows  Fuel storage – above ground with spill containment  Photovoltaic systems – on existing impervious surface, over pervious surface with vegetated cover, buffer strip at the most down gradient row of panels  Second story – no increase in building footprint  Decks & stairs & walkways – raised with space below for drainage  Temporary structures – in place less than 6 months  Trails and pathways, where no other impervious surfaces are replaced or created, and built to direct stormwater runoff to adjacent vegetated areas. Form revised: July 12, 2016 Vellum Design & Build BLDG-0438-2025 Enclave Lot 24 Lot 24 Hansen Lane, San Luis Obispo, CA 93401 004-719-024 SFR 4 N/A Construction of new residence on a existing lot. 10,737 SF 5,100 SF 0 0 5,038 SF 5,100 SF Stormwater Control Plan for Post Construction Requirements Otherwise, your project is subject to the Post Construction Requirements Project Site Details Step 3 Watershed Management Zone: Urban Sustainability Area Name: Meet USA Conditions See Area calculations in Step 1 to compare to thresholds in each Step below Where directions state “Go To”, fill out and attach the referenced Form and any supporting documents Step 4 Project is > 2,500 square feet Yes ‐ Go To Requirement 1 – Site Design & Runoff Reduction ‐ Form 1 AND THEN Go To Step 5 Step 5 Detached single family residential project where Area (e) is > 15,000 square feet OR Project where Area (e) > 5,000 square feet Yes ‐ Go To Requirement 2 – Water Quality Treatment ‐ Form 2 AND THEN Go To Step 6 No ‐ Done Step 6 Detached single family residential project where Area (e) > 15,000 square feet OR Project where Area (a+b) > 15,000 square feet AND is in Watershed Management Zone 4,7,10 over a ground water basin OR in Zone 1,2,5,6,8,9 Yes ‐ Go To Requirement 3 – Runoff Retention ‐ Form 3 AND THEN Go To Step 7 No ‐ Done Step 7 Project where Area (a+b) > 22,000 square feet AND is in Watershed Management Zone 1,2,3,6,9 Yes ‐ Go To Requirement 4 – Peak Management ‐ Form 4 No ‐ Done Exhibits 1.Watershed Management Zones 2.Groundwater Basin Location 3.Watershed Management Zone Revision Request 4.Urban Sustainability Conditions and Maps of Approved Areas Performance Requirement 3 Does Not Apply. Go to Step 7. 9 4 4 Stormwater Control Plan for Post Construction Requirements Form 1 Requirement 1 – Site Design and Runoff Reduction: Identify the strategies used to reduce runoff through site design. Strategies 1-5 required. Describe or attach simple plan details for 1. – 5. 1.Limit disturbance of creeks and natural drainage features and setback development from these features. 2.Minimize compaction of highly permeable soils 3.Minimize clearing of native vegetation and grading, conserving natural areas and maximizing undisturbed areas, and developing along natural landforms. 4.Minimize impervious surfaces including roadways and parking lots 5.Do one of the following:  Direct roof run off into cistern, rain barrel, or vegetated area Direct driveway, walkways, patios, and/or parking area into vegetated area Construct surfaces (bike lanes, walks, driveways, parking areas,patios) with permeable surfaces 6.Other (Optional): Identify strategy(s) and describe or show how it will be done in the project. No creeks or natural drainage features on lot. N/A, lot already rough graded. N/A, lot already rough graded House and flatwork limited to what is needed for this type of development. 4 Stormwater Control Plan for Post Construction Requirements Form 2 Requirement 2 – Water Quality Treatment: (Reference Post Construction Stormwater Management Requirements for Development Projects in the Central Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region – for details regarding requirements – Section B.3 and Section C. Alternative Compliance.) Treatment Location   On Site  Off Site - Alternative Compliance Measure Used   1. Harvesting, infiltration, evapotranspiration  2. Bio-filtration Treatment (Document inability to use 1.)  3. Non-Retention Based Treatment (Document inability to use 1. or 2.) Description of structural controls: Alternative compliance measures: Attachments  Attach treatment/sizing calculations, including any volume treated with off-site compliance.  Attach construction and planting details and specifications for bio-filtration options  Attach documentation regarding Treatment Measure selection  Attach infeasibility analysis where alternative compliance is proposed. Certification I certify that the systems selected and sized, as demonstrated in the attached calculations, meet the Water Quality Treatment required for this project per the Post Construction Requirements adopted by the Central Coast Regional Water Quality Control Board. Where identified in the attached documentation, Water Quality Treatment will be met through alternative compliance. Signature Date Stormwater Control Plan for Post Construction Requirements Form 3 Requirement 3 – Runoff Retention: (Reference Post Construction Stormwater Management Requirements for Development Projects in the Central Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region – for details regarding requirements – Section B.4 and Section C. Alternative Compliance.)  If a revision to the site’s Watershed Management Zone is being requested, attach Watershed Management Revision Request Form (Exhibit) and supporting documentation.  Rainfall maps are available from the Regional Water Quality Control Board Site Assessment Measures Summary  Attach documentation of the following information:  Site topography  Development envelope  Hydrologic features including natural areas, wetlands, watercourses, seeps, springs, and required setbacks  Vegetative cover including trees  Open space requirements  Location of groundwater wells used for drinking water  Depth to seasonal high groundwater  Soil types and hydrologic soil groups  Depth to impervious layer such as bedrock  Presence of unique geology (e.g. karst)  Geotechnical hazards  Existing structures, utilities, and drainage infrastructure including municipal storm drain system components  Existing easements and covenants  Documented soil or groundwater contamination  Source and estimated stormwater run-on from offsite, coming to project area  Drainage Management Areas (B.4.d.iii)  Drainage management strategies by Drainage Management Area  Runoff reduction measures and any structural control measures by Drainage Management Area (or full site as appropriate)  Technical infeasibility limits on-site compliance  10% of equivalent impervious surface area is dedicated to retention based stormwater control measures – No alternative compliance for retention Runoff volume - compliance not achieved on-site:  Alternative compliance for retention proposed Runoff volume – compliance not achieved onsite: Runoff volume – alternative compliance used: Analysis and Sizing  Attach calculated Tributary Areas and Design Volumes per the Post Construction Stormwater Management Requirements – Attachment D  Adjustment made for redevelopment  Adjustment made for being in, and meeting requirements of, an Urban Sustainability Area Stormwater Control Plan for Post Construction Requirements Form 3 Control Mechanism Site in Zone 1, 4, 7, and/or 10 and over groundwater basin  95th percentile event retained via infiltration  Finding of technical infeasibility – Structural Stormwater Measure proposed Site in Zone 2  95th percentile event retained via storage, harvesting, infiltration, and/or evapotranspiration  Finding of technical infeasibility – Structural Stormwater Measure proposed Site in Zone 5 and/or 8  85th percentile event retained via infiltration  Finding of technical infeasibility – Structural Stormwater Measure proposed Site in Zone 6 and/or 9  85th percentile event retained via storage, harvesting, infiltration, and/or evapotranspiration  Finding of technical infeasibility – Structural Stormwater Measure proposed Attachments  Attach Attachment D calculations for hydrologic analysis and stormwater control measure sizing  Attach discussion of technical infeasibility for structural stormwater measure, where proposed in lieu of preferred storage, harvesting, infiltration, and/or evapotranspiration, include justification for any non- retention based controls  Attach documentation of technical infeasibility for on-site compliance, including a site specific hydrologic and/or design analysis supporting findings  Attach description of alternative compliance project including a summary description of pollutant and flow reduction comparing the expected aggregate results of the alternate project to the results that would otherwise have been achieved by meeting the numeric performance requirements onsite.  Attach Attachment E calculations for retention requirement adjustment for technical infeasibility  Attach Attachment F calculations for off-site retention requirements  Attach agreement for alternative compliance site use, for purposes of achieving compliance  Attach Operations and Maintenance Plan for all stormwater control measures (include any Peak Management facilities) Post-Construction Owner Identification At the time of completion of the construction work, and the shift to post-construction stormwater controls, the below listed owner is responsible for Operations and Maintenance of stormwater control measures: (If responsibilities are divided, list all responsible owners and associated measures.) Certification I certify that the systems selected, sized, and designed as demonstrated in the attached calculations, meet the Runoff Retention Performance Requirement for this project per the Post Construction Requirements adopted by the Central Coast Regional Water Quality Control Board. Where identified in the attached documentation, Runoff Retention will be met through alternative compliance. Signature Date Stormwater Control Plan for Post Construction Requirements Form 4 Requirement 4 – Peak Management (Reference Post Construction Stormwater Management Requirements for Development Projects in the Central Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region – for details regarding requirements – Section B.5) Show any stormwater control measures used to meet the requirements of this section, in the documentation and attachments required for Retention (Form 3), including in all mapping and Operations and Maintenance materials. Peak Management Compliance  Post-development peak flows, discharged from the site, do not exceed pre-project peak flows for the 2 through 10 years storm events.  Technical infeasibility limits on-site compliance  Alternative compliance for retention proposed Runoff volume – compliance not achieved onsite: Runoff volume – alternative compliance used: Attachments  Attach calculations showing pre-project discharge and post-project discharge for the 2 through 10 year storm events  Attach documentation of technical infeasibility for on-site compliance, including a site specific hydrologic and/or design analysis supporting findings  Attach description of alternative compliance project including a summary description of pollutant and flow reduction comparing the expected aggregate results of the alternate project to the results that would otherwise have been achieved by meeting the numeric performance requirements onsite.  Attach agreement for alternative compliance site use, for purposes of achieving compliance Post-Construction Owner Identification At the time of completion of the construction work, and the shift to post-construction stormwater controls, the below listed owner is responsible for Operations and Maintenance of the peak management control measures: (If responsibilities are divided, list all responsible owners and associated measures.) Certification I certify that the systems selected, sized, and designed as demonstrated in the attached calculations, meet the Peak Management requirements for this project per the Post Construction Requirements adopted by the Central Coast Regional Water Quality Control Board. Where identified in the attached documentation, Peak Management will be met through alternative compliance. Signature Date Stormwater Control Plan for Post Construction Requirements Exhibit 1 Watershed Management Zones Stormwater Control Plan for Post Construction Requirements Exhibit 2 Ground Water Basin Stormwater Control Plan for Post Construction Requirements Exhibit 3 Watershed Management Zone Revision Request It is understood that Watershed Management Zones were developed through the Central Coast Regional Water Quality Control Board Joint Effort with available data, at varying degrees of detail and accuracy. Zones may vary across properties, or be off from verifiable, on the ground data. Applicants may propose revisions to the designate Watershed Management Zone for the project. Applicants should carefully review the Post-Construction Stormwater Management Requirements For Development Projects in the Central Coast Region, California – Technical Support Document for a clear understanding of the basis of the Watershed Management Zone designations before proceeding with this application. Site Information Project Address: Current Watershed Management Zone(s): Proposed Watershed Management Zone(s): Watershed Management Zone Summary Copy table for multiple zones in the Project area  Mark the characteristics supported by geotechnical observation in the column marked ”(P)”  Identify the page number in any geotechnical report reference in the column marked “Pg” Watershed Management Zone 1 2 3 4 5 6 7 8 9 10 (P) Pg Drains to: Stream   Wetland   Stream or Wetland     Lake  River  Lake or River   Underlain by: 0-10% All types  > 40% All types  4 0-40% Quaternary & Late Tertiary  10-40% Quaternary & Late Tertiary  0-10% Early to Mid-Tertiary  10-40% Early to Mid-Tertiary  10-40% Franciscan melange, Pre-Quaternary crystalline, Early to Mid-Tertiary 5 > 40% Quaternary, Late Tertiary, Early to Mid- Tertiary   0-10% Franciscan melange, Pre-Quaternary crystalline  > 10% Franciscan melange, Pre-Quaternary crystalline 2 10-40% Franciscan melange, Pre-Quaternary crystalline 3 > 40% Franciscan melange, Pre-Quaternary crystalline  Stormwater Control Plan for Post Construction Requirements Exhibit 3 Watershed Management Zone 1 2 3 4 5 6 7 8 9 10 (P) Pg Slope: Steep     Moderate     Low   Watershed Process: Infiltration dominant  1   Infiltration less dominant     Chemical & biological remediation   Overland flow minimal      Notes: 1 – Over groundwater basin 2 – Zone 9 Wetland Draining 3 – Zone 9 Stream or Wetland Draining 4 – Zone 10 Lake Draining 5 – Zone 10 Lake or River Draining Watershed Management Zone Revision Supporting Summary Provide written summary of geotechnical/geological information supporting revised Watershed Management Zone designation. Attachment  Attach geotechnical or geological information which supports revision (include page references in table above) Stormwater Control Plan for Post Construction Requirements Exhibit 4 Urban Sustainability Areas Urban Sustainability Areas (USA) encompass high density urban centers where the documented objective is to preserve or enhance and existing pedestrian-oriented and/or public transit-oriented type of urban design through the promotion of high density redevelopment and infill. Requirements for USAs The City has received approval for certain sub-areas within three land use zoning areas for USAs designation, superimposed with minimum requirements. The Zones are Retail Commercial, Downtown Commercial, and High Density Residential. Maps are provided at the end of this document. Site specific requirements relating to floor areas or dwelling units, surface parking allowance, and alternative transportation meet or exceed the current Zoning Regulation requirements. To be eligible for reductions of Post-Construction Requirements, development and redevelopment projects must meet all the USA requirements listed below for the Zone. A. Retail Commercial (C-R) USA Requirements  Ratio of gross building floor area to site area minimum = 3:1  Site area building coverage minimum = 90%  Project uses < 10% of area for surface parking  Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with connections to regional transit routes and train station  Provision of bike parking spaces = minimum 15% of auto parking requirement  Sidewalks provided on both sides of the street B. Downtown Commercial (C-D) USA Requirements  Ratio of gross building floor area to site area minimum = 3:1  Site area building coverage maximum = 100%  Project provides no surface parking, beyond incidental uses for emergency and ADA. Exception is municipal multi-story structures provided as park-in-lieu facilities for intense site developments  Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with connections to regional transit routes and train station  Provision of bike parking spaces = minimum 15% of auto parking requirement  Sidewalks provided on both sides of the street C. High-Density Residential (R-4) USA Requirements  Dwelling units per net acre (net acre - excludes right-of-way, creeks, endangered & threatened species habitat) minimum = 24 + a low or moderate income density bonus  Site area building coverage minimum = 60%  Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with connections to regional transit routes and train station  Provision of bike parking spaces = minimum 10% of auto parking requirement  Sidewalks provided on both sides of the street or approved alternative connection pathways Stormwater Control Plan for Post Construction Requirements Exhibit 4 Application of Post Construction Requirements within a USA Post Construction Requirements will be applied in USAs as follows: A. Performance Requirement No. 1: Site Design and Runoff Reduction  The City will apply those aspects of Site Design and Runoff Reduction that are applicable.  Site design activities may be limited by the pre-project condition and density goals.  Where complete, or nearly complete lot coverage is proposed, shifting of rainwater to vegetated areas, or for reuse may not be applicable. B. Performance Requirement No. 2: Water Quality Treatment  The City will apply Water Quality Treatment  Where Water Quality Treatment is demonstrated as infeasible, it will be handled per C.3.b  Site specific analysis completed and endorsed to show infeasibility per sections C.1.a & c  Off-site Project description, location within the same watershed, and scheduled completion date identified C. Performance Requirement No. 3: Runoff Retention  The City will apply Runoff Retention  Per B.4.b.ii, the total runoff volume to be retained from replaced impervious surfaces shall be less than, or equivalent to, the pre-project runoff volume retained  New impervious surfaces will comply with requirements of section B.4, calculated per Attachment D, where the tributary area is a function of new impervious only D. Performance Requirement No. 4 – Peak Management  The City will apply Peak Management Requirements  Post-development peak flows will generally not exceed pre-project peak flows for the 2 through 10 year storm events for redevelopment sites  Technical infeasibility will apply where density goals result in space constraints as provided for in C.1.c.v. Per C.1.a, and no site specific hydrologic or geotechnical analysis will be required. E. Off-Site Compliance  Where an off-site compliance proposal is included in the project submittal  Location, analysis for performance requirement compliance, and project mitigation completion schedule for off-site compliance will be required as part of the submittal.  Off-site compliance site will be within the same watershed, unless otherwise approved by the Central Coast Water Board EO. Stormwater Control Plan for Post Construction Requirements Exhibit 4 Maps of Approved USAs A. Retail Commercial (C-R) Stormwater Control Plan for Post Construction Requirements Exhibit 4 Stormwater Control Plan for Post Construction Requirements Exhibit 4 B. Downtown Commercial (C-D) Stormwater Control Plan for Post Construction Requirements Exhibit 4 C. High-Density Residential (R-4) Stormwater Control Plan for Post Construction Requirements Exhibit 4