CITY OF SAN MATEO
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CITY OF SAN MATEO
Agenda Report
City Hall
330 W. 20th Avenue
San Mateo CA 94403
www.cityofsanmateo.org
Agenda Number: 6 Section Name: CONSENT CALENDAR Account Number: 72-4671 File ID: 26-10979 TO: City Council
FROM: Alex Khojikian, City Manager
PREPARED BY: Public Works Department
MEETING DATE: April 06, 2026
SUBJECT:
Clean Water Program Annual Major Components Dissolved Air Flotation Tank Replacement — Agreement RECOMMENDATION:
Adopt a Resolution to authorize an alternative purchasing procedure to enter into an agreement with Carollo Engineers, Inc. to provide design professional services for the Wastewater Treatment Plant Dissolved Air Flotation Tank Replacement Project, in an amount not to exceed $964,300; establish a contingency reserve of $145,000; and authorize the Public Works Director to execute this agreement and task amendments within the contingency amount in substantially the form presented.
BACKGROUND:
The City is currently under a Regional Water Quality Control Board Cease and Desist Order requiring improvements to its sewer collection system and Wastewater Treatment Plant (WWTP) to eliminate sanitary sewer overflows and unauthorized discharges of untreated or partially treated wastewater to San Francisco Bay. The Clean Water Program (CWP) includes several capital improvements that are currently under construction and intended to comply with the Cease-and-Desist Order.
As part of the CWP, the City has identified essential capital improvements required to sustain and enhance the reliability, performance, and safety of the WWTP. These improvements are categorized as Annual Major Components (AMC) Projects.
In August 2022, following a Request for Proposals process, City Council approved agreements with Carollo Engineers, Inc. (Carollo) and Brown and Caldwell LLC (Brown and Caldwell) to provide on-call professional consulting services in support of the City’s planned rehabilitation of the existing WWTP, including AMC Projects. The on-call professional consulting services include but are not limited to; alternatives analyses and engineering studies; design services; bid period services; engineering services during construction; and operational support. Each agreement authorized a total of up to $400,000 for services performed on an on-call basis. The contract terms are three years, with the option for two additional one-year extensions and an additional budget of up to $100,000 per year.
One of the AMC projects identified was an Evaluation of the Dissolved Air Flotation Tank (DAFT) system, a critical component of the WWTP’s solids handling process. The aging DAFT system is deteriorating with significant corrosion, necessitating an urgent upgrade to maintain compliance with performance targets and ensure reliable operations.
Furthermore, the current configuration lacks redundancy, exposing the system to elevated operational risk.
In October 2024, the City solicited proposals from the two on-call consultants for the Waste Activated Sludge (WAS) Thickening Analysis Study, aimed at evaluating the DAFT system’s condition and identifying whether structural rehabilitation or a complete replacement presents the most viable path forward for the treatment plant. Proposals from Brown and Caldwell and Carollo were evaluated and Carollo was selected to conduct the study. Carollo facilitated multiple workshops with City staff to review findings and align the preferred solution. The study’s final recommendation is to
CITY OF SAN MATEO
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replace the existing DAFT technology with a new rotary drum thickener (RDT) facility. Through this process, Carollo developed a deep understanding of the City’s solids handling system, operational challenges, and long-term operations and maintenance requirements of the DAFT system.
San Mateo Municipal Code Section 3.60.070(h)(3) authorizes the City Council to approve an alternative purchasing procedure when it finds doing so is in the best interest of the City. It is in the City’s best interest to award Carollo the next phase of this project, the detailed design phase, because Carollo’s preceding work provides continuity of expertise, ensuring technical consistency between the study’s recommendations and the detailed design. This minimizes redundancy in effort and ensures that the design reflects the operational needs already identified by City staff. The scope of this phase includes development of the basis of design, preparation of preliminary design, and completion of detailed design through 100% bid-ready construction documents.
City staff recommends awarding the DAFT Replacement Project to Carollo for the reasons outlined above, as this approach is the most beneficial and effective for both the City and the WWTP. The project was envisioned to be issued under the existing On-Call Professional Consulting Services Agreement with Carollo; however, due to the level of effort required for a new DAFT technology design, a separate agreement is recommended.
Staff negotiated a fee of $964,300 to complete the Project’s scope of services. Staff also recommends a contingency reserve of $145,000 (15% of fee) to address potential unforeseen conditions, site-specific challenges, or scope refinements that may arise during project execution.
BUDGET IMPACT:
There are sufficient funds available in the CWP WWTP Annual Major Components (46t090) project budget to fund this agreement and contingency reserve.
ENVIRONMENTAL DETERMINATION:
Approval of this agreement for design professional services to support the DAFT Replacement Project is categorically exempt from CEQA review as an “existing facility,” in that it consists of the operation, repair, maintenance, permitting, leasing, licensing, or minor alteration of existing public or private structures, facilities, mechanical equipment, or topographical features, involving negligible or no expansion of existing or former use. (CEQA Guidelines Section 15301.)
NOTICE PROVIDED
All meeting noticing requirements were met.
ATTACHMENTS
Att 1 – Proposed Resolution
Att 2 – Agreement
STAFF CONTACT
Thomas Ruark, Senior Project Manager
[email protected]
(650) 522-7280
Thomas W. Williams, Engineering Manager
[email protected]
(650) 522-7307
James O'Connell, Deputy Director of Public Works
[email protected]
(650)522-7304