DATE: August 4, 2025
TO: Mayor and Members of the City Council
VIA: Stefan Chatwin, City Manager
Marlene Subhashini, Assistant City Manager
FROM: Andrew Brozyna, Public Works Director/City Engineer Laura Galli, Engineering Manager
Francine Magno, Senior Civil Engineer
DEPARTMENT: Public Works
SUBJECT: CONTRACT AMENDMENT NO. ONE (1) IN THE AMOUNT OF $139,570 WITH JDH CORROSION CONSULTANTS, INC. FOR
CORROSION ENGINEERING SERVICES FOR SEAWALL
CORROSION MONITORING
RECOMMENDATION
It is recommended that the City Council adopt the attached resolution authorizing:
The Mayor to execute Contract Amendment No. One (CA #1) to the Agreement with JDH Corrosion Consultants, Inc. (JDH) dated June 18, 2024 in the amount of $139,570 for ongoing corrosion engineering services for seawall corrosion monitoring for a three (3) year term; and
Establishing a contingency in the amount of $14,000, with authority given to the City Manager or his designee, to execute Contract Amendments up to the contingency amount.
EXECUTIVE SUMMARY
Corrosion monitoring services are necessary to provide corrosion monitoring and assessment of the seawall installed as part of the Levee Protection Planning and Improvements Project (Levee Project) (CIP 327-657). JDH provided corrosion monitoring
services of the levee sheet pile wall for the first-year post-construction (FY 24/25). In order to provide continual corrosion monitoring and maintain continuity, CA #1will extend the terms of the initial Agreement by three (3) additional years and add scope to replace the original steel coupons used as part of the weight loss monitoring of the steel wall. The proposed fees, for the not-to-exceed amount of $139,570, to be distributed over the next three (3) years, have been determined reasonable. Funding for the scope of work in FY25-26 is available in the approved Public Works Lagoon & Levee operating budget.
BACKGROUND
The Levee Project construction, completed in February 2024, includes approximately 6- miles of seawall (made from interlocking hybrid steel sheet piles) to protect the City from sea level rise. Given the conductive environment surrounding the seawall, it was established during design, that corrosion monitoring would be necessary to monitor the thickness of the steel panels and establish rates of corrosion trends. These trends will be continuously monitored over time and compared to baseline data to inform future actions and strategies to maintain the long-term protection of the structure.
Corrosion monitoring systems were installed at various points along the levee during construction to monitor the actual corrosion rate of the seawall. These systems include:
Electrical resistance monitoring probes - cylindrical probes that measure electrical resistance. Metal loss due to corrosion is quantified by a proportionate increase in an element’s electrical resistance.
Weight loss monitoring coupons - coupons of the same steel as the seawall set at varying elevations adjacent to the seawall; the coupons are extracted then weighed to track how much material has corroded based on weight. Ultrasonic thickness test sites – designated locations used for non-destructive testing using ultrasonic waves to measure the thickness of the seawall.
On June 18, 2024, the City Manager executed an Agreement with JDH for corrosion monitoring services for the first-year post-construction. JDH performed two surveys over the past year and provided a report summarizing their findings. The report concluded that based on the current calculated rate of corrosion, overall, the seawall is expected to exceed its 80-year design life without mitigation. However, one segment of above-ground seawall north of the San Mateo Bridge (approximately 3,300 feet in length) was identified for treatment. The bay facing portion of this particular section is subject to high levels of wind driven atmospheric corrosion. It is recommended that it receive treatment (protective coating) within the next 5 years to extend its useful life. Staff will program these coating improvements into the 5-year CIP during next year’s budget cycle.
JDH’s initial efforts have established baseline corrosion rates for various points along the levee. It is necessary to continue corrosion monitoring to observe how the corrosion rates will change over the next few years and the extent of any mitigation that will be required in the future.
ANALYSIS
The scope of work for the initial Agreement with JDH included:
Electrical resistance and weight loss monitoring (every 6 months) Atmospheric corrosion visual inspection and ultrasonic testing (thickness measurements) of the wall (annually)
Preparation of report documenting findings and providing recommendations (after each monitoring survey, every 6 months)
CA #1 extends the terms of the initial Agreement for three (3) years. The scope for each year will include:
The scope items identified above
Additional effort for report preparation based on the addition of extra monitoring data
Additional scope to replace select corrosion monitoring coupons that have been extracted at various time intervals since installation in 2021. To extend the useful life of the new corrosion monitoring coupons, the coupons will be thicker in dimension and coated to better simulate the corrosion experienced by the sea wall.
Staff has been satisfied with JDH’s performance to date. In addition, JDH was involved with the design of the corrosion monitoring elements that were installed as part of the Levee Project and is familiar with the system as constructed. With the City Council’s approval of the attached resolution, JDH will proceed with the monitoring services for year 2 identified in the scope. The first monitoring survey for FY 25/26 is expected to occur later this month.
CEQA
An Environmental Impact Report was prepared for the Levee Protection Planning and Improvements Project (State Clearinghouse No. 2016012012). The services that will be provided under this Amendment were contemplated as part of the Project that was considered in the EIR.
FISCAL IMPACT
Funding for corrosion monitoring for the current fiscal year (FY 25/26) is already available in the General Fund under Public Works Lagoon & Levee Division Operating Budget and was approved during the most recent budget process. Funding for work in subsequent years will be requested as part of the annual budget process.
CITY COUNCIL VISION, MISSION, AND VALUE/PRIORITY AREA
Facilities and Infrastructure
ATTACHMENTS:
Attachment 1 – Resolution
Attachment 2 – Contract Amendment No. One (1)