CITY OF SAN MATEO
CITY OF SAN MATEO
Agenda Report
City Hall
330 W. 20th Avenue
San Mateo CA 94403
www.cityofsanmateo.org
Agenda Number: 10 Section Name: {{section.name}} Account Number: 72-4671 File ID: {{item.tracking_number}} TO: City Council
FROM: Alex Khojikian, City Manager
PREPARED BY: Public Works Department
MEETING DATE: May 19, 2025
SUBJECT:
Wastewater Treatment Plant, Digester 2 Coating Project – Agreement Approval RECOMMENDATION:
Approve an Agreement with Brand Safway to conduct Wastewater Treatment Plant Digester 2 Coatings in an amount not to exceed $406,881.35; approve a contingency of $82,000.00; and authorize the Public Works Director to execute the agreement in substantially the form presented and approve any necessary change orders within the approved contingency amount.
BACKGROUND:
The Clean Water Program (CWP) Annual Major Components (AMC) Projects includes several capital improvement projects that are currently under development or under construction and are intended to upgrade or rehabilitate aging infrastructure in the City’s sewer collection system and Wastewater Treatment Plant (WWTP). The AMC includes the WWTP Biogas and Biosolids Evaluation project which is being conducted by Brown and Caldwell (B&C). The scope includes the condition assessment and inspection of both digesters. An initial condition assessment of Digester 2 was recently completed and revealed that the coatings of the draft tube and interior of Digester 2 need repair. This will help prevent wear and tear related issues caused by the composition of digester sludge and gas.
Digester 2 is currently offline due to the mixer failure in 2022, which is being repaired off site and expected back in late May 2025. The WWTP is currently operating with only Digester 1, which is the older of the two Digesters, and there is concern about its current condition. It is in the City’s best interest to bring Digester 2 online as soon as possible. Operating the plant with only Digester 1 causes an increase in the liquid content in the off-haul material. This has increased the operational cost of hauling the material by $26,000 per month.
With Digester 2 offline, the City performed a cleaning and condition assessment of Digester 2 in the second week of March. To perform the condition assessment, an internal temporary scaffold was installed. Because the digester is egg shaped, the scaffold is complex and is costly to install. After the inspection and preliminary evaluation was performed, it was recommended to re-coat the digester and draft tube because the existing coating has worn off. Without the coating, the interior of the digester would be subject to corrosion which can cause issues with Digester 2 condition and performance. Given the results of this evaluation, the City deems it is most cost effective to re-coat the interior of the digester and draft tube while Digester 2 is currently offline, and the scaffolding is in place. This avoids the costs of dismantling and installing the scaffolding and recleaning the digester if the recoating is not performed while the digester is currently offline. In addition, taking a digester offline is not a simple process as it involves ensuring the gases are purged, which takes significant effort from the WWTP operations and maintenance staff.
In April 2025, the City obtained three proposals from three local coating vendors – JeffCo, Brand Safway (which owns National Coatings), and Redwood. City staff evaluated the proposals and determined Brand Safway as the lowest bidder to
CITY OF SAN MATEO
perform the work. They also demonstrated experience with this scope. The base amount for this project is $406,881.35, which includes labor, material, coating per manufacturer specifications, decontamination, dehumidification, and onsite power. In addition, staff recommends $82,000 be authorized as a contingency amount for any potential changes that may arise due to the nature of this work. The approximate duration of this work is 27 working days.
BUDGET IMPACT:
There are sufficient funds available in the CWP WWTP Annual Major Components Project (46T090) to fund this agreement and the proposed contingency reserve.
ENVIRONMENTAL DETERMINATION:
This project is categorically exempt from CEQA as an “existing facility,” because 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 use. (CEQA Guidelines Section 15301.)
NOTICE PROVIDED
All meeting noticing requirements were met.
ATTACHMENTS
Att 1 – Agreement
STAFF CONTACT
Thomas Ruark, Senior Project Manager
[email protected]
650-522-7280
Deryk Daquigan, Deputy Director of Public Works
[email protected]
(650)522-7287
Matthew Fabry, Director of Public Works
[email protected]
(650)522-7303