HomeMy WebLinkAboutItem 6l - Authorize Change Order for Wastewater Collections Infrastructure Renewal Strategy and Wastewater Flow Model Item 6l
Department: Utilities
Cost Center: 6101
For Agenda of: 10/6/2026
Placement: Consent
Estimated Time: N/A
FROM: Aaron Floyd, Public Works & Utilities Director
Prepared By: Shawna Scott, Assistant Director of Utilities
SUBJECT: AUTHORIZATION OF A CHANGE ORDER FOR THE WASTEWATER
COLLECTIONS INFRASTRUCTURE RENEWAL STRATEGY AND
WASTEWATER FLOW MODEL
RECOMMENDATION
Authorize a change order in the amount of $102,437 for the Wastewater Collections
Infrastructure Renewal Strategy and associated Wastewater Flow Model.
REPORT-IN-BRIEF
The original contract agreement for the Wastewater Collections Infrastructure Renewal
Strategy and associated Wastewater Flow Model was executed in 2023 in the amount of
$428,718. Since that time, subsequent budget augmentations and change orders have
been issued to address expansions in the scope of work, which has resulted in a superior
long-range capital plan for the wastewater collections system and associate d citywide
flow model. Subsequent change orders were subject to the City Manager ’s approval,
consistent with City purchasing thresholds for professional services. The project has been
completed, and the final change order, in the amount of $102,437, results in a cumulative
change order amount of $178,937.
Pursuant to the City’s Financial Management Manual, City Council approval is required
for cumulative change orders exceeding $150,000. The final resulting scope of work and
associated fiscal investment results in numerous community-wide benefits, as the level
of data collection and analysis is put to use to evaluate build -out of the General Plan,
accommodation of housing and increased infill density, strategic actions for spill
prevention, improved prioritization for sewer system capital projects and associated short
and long-range budgeting forecasts and rate analysis.
POLICY CONTEXT
The Wastewater Collections Infrastructure Renewal Strategy supports Major City Goals
including Economic Recovery, Resiliency, and Fiscal Sustainability and Climate Action,
Open Space, and Sustainable Transportation because it will provide the analysis, data,
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and recommendations supporting ongoing and future investments in critical infrastructure
(wastewater collection) capacity and resiliency.
The Project is consistent with the City’s adopted General Plan. Water and Wastewater
Element (WWE) Policy B.2.2.2 (Service Capacity) states that “the City's wastewater
collection system and Water Resource Recovery Facility shall s upport population and
related service demands consistent with the General Plan”, and Program B.2.3.1 calls for
the City to expand capacity in the collection system in support of projected wastewater
flows. The Project supports this policy and program, and consistent with the WWE will
provide the information and recommendations necessary to: 1) manage the collection
system and ensure that flow does not exceed design capacity (Policy B.4.2.1); 2)
continue, modify, and identify programs that will minimize stor mwater and groundwater
infiltration and inflow into the sewer system (Policy B.4.2.2); and 3) investigate and carry
out cost-effective methods for reducing infiltration and inflow (I/I) into the collection system
(Program B.4.3.1).
As noted above, pursuant to the City’s Financial Management Manual, City Council
approval is required for cumulative change orders exceeding $150,000.
DISCUSSION
Background
On August 16, 2022, the City Council authorized inviting bids for the Wastewater
Collection Infrastructure Renewal Strategy (IRS) and flow study update (Project)
(Specification No. 91736 [previous project number]) and an initial budget of $430,000.
The scope of the Project included analysis of existing conditions, future build-out including
infill development, and increased densities in the City pursuant to the City’s General Plan.
The scope also included evaluation of the success of the ongoing Wastewater Flow Offset
Program and refinement of the boundaries of the Capacity Constrained Area Map.
Following the standard bid process, West Yost was determined to be the most qualified
and lowest responsible bidder with a bid of $428,718 and was awarded the contract.
Subsequent to the award, three budget augmentations and two change orders associated
with additional work scope items were approved and processed for the project, which are
summarized below (also refer to Table 1, Approved and Requested Budget
Augmentations and Change Orders).
In October 2023, an expansion of work scope (and associated $59,500 change order,
“Change Order 1”) was approved to conduct additional wastewater flow monitoring
beyond what was identified in the base scope of work to capitalize on ra infall weather
forecasts and improve the data collection and modeling analysis. While the project was
underway, staff and the consultant were made aware of a far superior hydraulic modeling
software (Aquanuity’s AquaTwin Sewer) and requested the switch from the previously
originally identified SewerGems software. This change required a second change order
in the amount of $17,000 (“Change Order 2”). AquaTwin is a superior hydraulic modeling
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software that more efficiently fulfills the development of the Wast ewater Collection
Infrastructure Renewal Strategy. In particular, this new software more efficiently identifies
and prioritizes capital projects, improves future modeling of development projects and
General Plan updates, and more effectively evaluates the progress of the Wastewater
Flow Offset Program. Additionally, this software enabled the consultant to more
accurately update the Wastewater Capacity Constrained area map.
In March 2025, the consultant submitted a request for additional budget augmentation to
incorporate data from the previous model and rerun five modeling scenarios based on
updated invert elevation data.1 The project budget was augmented by $36,228 (“Change
Order 3”, resulting in a total budget of $541,446), but the City postponed execution of an
agreement change order, as there was a possibility that the consultant could complete
this work under the approved budget amount.
As the project continued to progress along a critical timeline for completion, additional
necessary scope changes were identified by staff in consultation with the consultant. This
additional work included recalibration of the wastewater model using operational run -time
data from several lift stations to better reflect actual system conditions, redistributing
inflow and infiltration within the wastewater collections system, updated system capacity
evaluation, utilization of the model to plan for more immediate City and private housing
development projects, refinement of recommended capacity improvement projects, and
corresponding updates to the final report.
This work improved the reliability of the model and strengthened the technical basis for
capital planning and private project analysis, and the value of the new software and
collaborative and deliberate approach to the analysis has far exceeded the additional
costs. The work has been completed, and a change order is requested to increase the
contract amount to compensate the consultant for these additional services which were
incorporated into the Infrastructure Renewal Strategy Project, updated Wastewater
Collections System Capacity Constrained area map, and flow model (City Council Item
6b 12/2/2025).
The final budget augmentation is in the amount of $66,209 (“Change Order 4”), which
was included in the 2025-27 Financial Plan Supplement adopted by the City Council in
June 2026. Therefore, including the postponed $36,228 change order identified above,
the total requested contractual change order is in the amount of $102,437. T his brings
the total contracted amount to $607,655, which is equal to the total budget identified in
the 2025-27 Financial Plan Supplement for this project.
1 Invert elevation is the vertical elevation of the bottom interior of a pipe and is a key parameter used to
determine flow direction and ensure wastewater can be conveyed by gravity through the collection
system.
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Table 1. Approved and Requested Budget Augmentations and Change Orders
Change Order Date Change Amount Running Contract Amount
Original Award Amount 03/27/2023 $0 $428,718
Change Order 1 10/19/2023 +$59,500 $488,218
Change Order 2 4/16/2024 +$17,000 $505,218
Change Order 3 Pending +$36,228 $541,446
Change Order 4 Pending +$66,209 $607,655
Total Change Amount $178,937
Staff recognize and are aware that this process and chain of events is not standard. Staff
do not typically authorize out-of-scope work prior to completion of a change order and
associated approvals; in this unique circumstance th ere was a need for the consultant to
proceed under a compressed timeline to meet the approval date for the Infrastructure
Renewal Strategy and the City Council’s consideration of an updated wastewater capacity
constrained area map, incorporate adequate time for public outreach prior to the Council
date, and to enable use of the updated model for private development projects
undergoing entitlement review.
Previous Council or Advisory Body Action
On August 16, 2022, the City Council authorized inviting bids for the Wastewater
Collection IRS and flow study update (Project) (Specification No. 91736 [previous project
number]).
On August 19, 2025, staff held a study session with the City Council to receive and file
the 2025 Wastewater Collection System Infrastructure Renewal Strategy, present the
updated capacity-constrained boundary map, and provide updates on the city's private
sewer lateral and rebate programs.
The 2025-27 Financial Plan Supplement adopted by the City Council in June 2026
identifies a budget line item in the amount of $66,209, which brings the total budget for
the project in the amount of $607,655,
Subsequent actions that utilized the completed 2025 Wastewater Collection System
Infrastructure Renewal Strategy and associated flow model included adoption of the
current Wastewater Collections System Capacity Constrained Area Map and Water and
Wastewater Element Amendment:
On October 22, 2025, the Planning Commission adopted Resolution No. PC-1112-
2025 recommending the City Council adopt amendments to the Water and
Wastewater Element of the General Plan (GENP-762-2025.
On December 2, 2025, the City Council adopted amendments to the Water and
Wastewater Element of the General Plan (GENP -762-2025, Resolution No.
11616), adopted amendments to the Sewer Lateral Rebate Program (Resolution
No. 11617).
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On April 21, 2026 (Introduction) and May 5, 2026 (Second Reading and Adoption),
the City Council adopted Ordinance Amendments related to the Sewer Later al
Inspection, Repair, and Replacement Program (Ordinance 1756).
Public Engagement
As summarized in the Council reports linked above, Utilities Department conducted
extensive public outreach and education related to the work efforts identified above, and
continue to engage with the public, developers, and realtor groups regarding the
wastewater flow study and model, Capacity Constrained Area Map, Ordinance
requirements, and rebate programs.
CONCURRENCE
The Finance Department concurs with the required purchasing authority procedure for
the requested change order.
ENVIRONMENTAL REVIEW
The City Council found the 2025 Wastewater Collections System Infrastructure Renewal
Strategy project statutorily exempt from the California Environmental Quality Act (CEQA)
pursuant to CEQA Guidelines Section 15262 (Feasibility and Planning Studies) and
categorically exempt from CEQA pursuant to CEQA Guidelines Section 15301 (Exi sting
Facilities). The City prepared and filed a Notice of Exemption for the project in accordance
with CEQA. The completed scope of work associated with the requested change order is
consistent with the CEQA determination.
FISCAL IMPACT
Budgeted: Yes Budget Year: 2026-27
Funding Identified: Yes
Fiscal Analysis:
Funding Sources
Total
Budget
Available
Current
Funding
Request
Remaining
Balance
Annual
Ongoing
Cost
2001023-Wastewater
Collections System
Infrastructure
Renewal Strategy
$102,437 $102,437 $0 $0
Total $102,437 $102,437 $0 $0
The 2025-27 Financial Plan Supplement adopted by the City Council in June 2026 added
funding in the amount of $66,209, which brings the total budget for the project in the
amount of $607,655. As described above, the requested chan ge order in the amount of
$102,437 is the sum of two pending change orders in the amounts of $36,228 (budget
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augmentation previously processed) and $66,209 (approved in the Financial Plan
Supplement).
ALTERNATIVES
1. Denial of the Change Order Request. The City Council may deny the change order.
While it is not typical for a consultant to proceed with out-of-scope work items outside
of a contract change order amendment, West Yost took on the financial risk based on
the scheduling needs of the City and for the benefit of our community. The expedited
work was necessary and justified to provide the most accurate data and modeling
results informing important decisions by the City Council (adoption of the capacity
constrained area map) in addition to fu ture modeling of wastewater flows associated
with private land development in the City in support of the General Plan. In addition,
the full cost of the project has been accounted for, as approved in the Financial Plan
Supplement.
ATTACHMENTS
A – West Yost Final Change Order Request
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1001 Galaxy Way
Suite 310
Concord CA 94520
925.949.5800 phone
530.756.5991 fax
westyost.com
September 26, 2025 Project No.: 1027-60-23-02
SENT VIA: EMAIL
Chris Lehman
Deputy Director - Wastewater
City of San Luis Obispo
879 Morro Street
San Luis Obispo, CA 93401
SUBJECT: Budget Augmentation Request for Project Completion
Dear Chris:
West Yost Associates (West Yost) appreciates the opportunity to serve the City of San Luis Obispo as the
engineer for the City’s Infrastructure Renewal Strategy. Following up on our discussion and understanding
from March of this year, this letter describes additional efforts required for items that were not
anticipated in our original scope of work. Accordingly, we are presenting West Yost’s costs associated with
the additional level of effort and request authorization to bill for the services provided. These include:
• Interim Use of Old Model: Patrick worked with the old sewer model to determine if it could
be used to provide analyses for development proposals and one sewer replacement project
that the City needed assistance with in advance of the updated model and analysis.
• Additional Data Updates: The updated invert elevation data provided on several recent
occasions triggered some unanticipated impacts. Once the model was up and running, each
iteration required a couple of days adjusting and checking four or five modeling scenarios
using the revised invert data.
• New Modeling Software: The conversion from SewerGems to Aquanuity’s AquaTwin Sewer
modeling software proved to be more time consuming than predicted. The City authorized a
budget augmentation (Amendment 2) of $17,000. The actual level of effort is difficult to
capture since during the course of conversion and troubleshooting, we were simultaneously
making progress updating the model.
In the interest of keeping the Project moving forward expeditiously, West Yost has completed these
out-of-scope items and billed them, as detailed on our monthly invoices. At the time the work was
performed, there was indeed a possibility that our contracted budget would have been adequate to
include these additional services. In March, we estimated that the budget impact of these additional
services was between $37,000 and $47,000. Some portions of our scope required less budget than
anticipated, so the net impact was expected to be less than $47,000.
Subsequently, additional work was requested as the project progressed. After completion of the hydraulic
analysis and identification of capacity improvement projects, the City requested that the model be
recalibrated using data provided from several of the City’s lift stations. This effort included analyzing lift
station run-time records and using that analysis to estimate flows, recalibrating the model by
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Chris Lehman
September 26, 2025
Page 2
N-C-1027-60-23-02-PM-B-l
redistributing the inflow and infiltration within the system, redoing the capacity analysis of the system
using the recalibrated hydraulic model, redoing the list of capacity improvement projects to address the
identified capacity deficiencies, and updating the final report to include the findings of the updated
analysis. We proceeded with the additional services in accordance with our mutual understanding that
the budget would be increased to accommodate the additional work.
This later effort required about 215 hours with a cost of $66,200. The net total for all the above added
services is $102,437, based on actual hours recorded plus a small allowance for producing the final report.
We request a budget increase in that amount. With this increase, the total contract amount would increase
from $505,218 to $607,655. The breakdown of the $102,437 by hours and staff member is as follows:
• 36 hours for Jeff Pelz, billed as Vice President
• 131 hours for Chris Malone, billed as Principal Engineer II
• 104 hours for Patrick Johnston, billed as Principal Engineer I
• 8 hours for Joe Bryant, billed as Technical Specialist II
• 17 hours for Manny Jimenez, billed as Technical Specialist I
• 18 hours for Mika Mar, billed as Engineer I
• 24 hours for Word Processing Support, billed as Administrative IV
Please review our request and call me at your earliest convenience if you would like to discuss in more
detail. Thank you for your consideration in this matter.
Sincerely,
WEST YOST
Patrick Johnston
Principal Engineer
RCE #59028
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