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APPROVE MOTION TO AUTHORIZE CONTRACT AMENDMENT NO. 2 WITH BROWN AND CALDWELL FOR THE PRESSURE-BASED DIGESTER GAS CONTROL SYSTEM FOR THE RWCF COGENERATION PLANT PROJECT
recommended action
RECOMMENDATION
It is recommended that the City Council approve a motion authorizing Standard Agreement Amendment No. 2 with Brown and Caldwell of Rancho Cordova, CA, for the Pressure-Based Digester Gas Control System for the Regional Wastewater Control Facility Cogeneration Plant Project. If approved, Amendment No. 2 will reinstate the contract, add $70,257 in funding, and extend the term to December 31, 2027, bringing the total contract amount to $268,304.
It is further recommended that the City Manager be authorized to take appropriate and necessary actions to carry out the purpose and intent of this Motion.
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Summary
The Municipal Utilities Department (MUD) operates the City’s Wastewater Utility, which includes a sanitary sewer collection system of approximately 900 miles of gravity sewer main, 554 miles of lower lateral pipe, 27 pump stations, and 30 miles of pressurized force main that convey sewage to the Regional Wastewater Control Facility (RWCF) for treatment.
The RWCF’s anaerobic digestion process generates biogas that powers cogeneration engines. A failed relief valve took the gas holding tank offline. As part of the repairs, the City is completing the design of a pressure-based fuel control system that will allow digester gas to bypass the tank and feed directly into the engines.
If approved by City Council, Amendment No. 2 (Attachment A) will reinstate the contract with Brown & Caldwell, add $70,257 in funding, and extend the term to December 31, 2027, bringing the total contract amount to $268,304.
DISCUSSION
Background
On September 30, 2024, MUD issued a Request for Proposals to design a pressure-based cogeneration engine fuel control system that would bypass the gas holding tank and deliver digester gas directly to the cogeneration engines. Brown & Caldwell (B&C) was the only firm to submit a proposal that met project requirements and was accepted by the selection committee.
On March 3, 2025, the City Manager approved a Professional Services Contract with B&C for $77,474 to review the existing volume-based digester gas controls and develop an approach for implementing the desired pressure-based system using existing equipment.
During their review, B&C identified additional system performance improvements, including mechanical modifications to the blowers and emergency flares. Additional engineering services were needed to design these improvements and support startup and commissioning of the new pressure-based control system.
On January 13, 2026, the City Council approved Motion 2026 01 13 1207, authorizing Amendment No. 1 for $120,573 to complete these additional design efforts and provide commissioning support.
On May 1, 2026, the contract with B&C expired before all engineering tasks could be completed. Engineering assistance is still required to finalize the pressure-based fuel control system and support startup and commissioning activities. B&C continued providing these critical services during the lapse period.
Present Situation
B&C completed the 60% design package for the pressure-based digester gas control system; however, work paused when Digester 4 failed and was taken offline. Because the control system depends on both Digesters 4 and 5 being operational to verify design assumptions and support commissioning, engineering progress cannot continue until Digester 4 is restored. As a result, B&C needs additional time and scope to finalize the design and resume startup and commissioning support once the digester returns to service.
Amendment No. 2 adds the final design phase, including 100% design drawings, specifications, and bid documents, and extends project management services. These tasks were not included in the original contract or Amendment No. 1, which only funded preliminary evaluation and partial design. Final design, listed as Task 4, was identified in Amendment No. 1 as a future phase to be completed after the 60% design was finished.
If approved, Amendment No. 2 will reinstate and extend the contract through December 31, 2027, and add $70,257, bringing the total contract amount to $268,304. The amendment will allow B&C to complete the project once Digester 4 is back online.
FINANCIAL SUMMARY
There are sufficient funds available in account number 6518-000-800007-610-612-00-65-000-000, CIP Pressure-Based Digester Gas Control System for the Regional Wastewater Control Facility Cogeneration Plant, Project No. UW24013, for the proposed Reinstatement of Contract No. 425000463 and addition of $70,257.
This action has no impact on the General Fund or any other unrestricted funds.
Attachment A - Standard Agreement Amendment No. 2