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Underground Flow Equalization System

UFES Project Update – April 2, 2024

Initial Operations of Underground Flow Equalization System Successful

The Underground Flow Equalization System (UFES) Project is moving steadily towards completion. While some finishing touches are being completed, the main system has been operational since December 2023. Since then, we have experienced 4 major rain events, during which the system has temporarily held a total of approximately 8 million gallons of diluted wastewater. This is an early indication of the success of the system achieving the goal to significantly reduce the number of sewer system overflows in the San Mateo area.

The City’s contractor continues to demobilize from the site. Major traffic impacts related to the UFES project along S. Delaware Street have concluded, and are nearing completion on Saratoga Drive. Minor occasional traffic inconveniences will continue as the overall project progresses through the final site finishing activities.

The City has also discontinued dust and noise monitoring in the vicinity of the San Mateo County Event Center Site, another sign of significant progress towards project completion. Potential violations and resulting risks from construction-related dust and noise were a concern for many residents near the site at the start of construction; however, no significant construction-related concerns were observed during the monitoring timeframe.

The City anticipates that the UFES project in its entirety, including work at the San Mateo County Event Center, will conclude in early Summer 2024.

We thank you for your continued patience and cooperation as we make steady progress toward the completion of our sewer system improvements.

Approved work hours are as follows:
San Mateo County Event Center Site: 7 a.m. – 7 p.m.
Saratoga Drive: 7 a.m. – 5 p.m.
South Delaware Street: 7 a.m. – 5 p.m.

*Construction schedules and traffic patterns are subject to change.

Representation of Phase 6 Finished Site
Visualization of finished construction

Stay Connected with the UFES Project

The Clean Water Program’s UFES construction is well underway and we want to keep you informed. The team established multiple information channels for residents and business owners to stay connected.

  • Sign up for construction alerts (text the word UFES to 1-833-321-0231), email us at or call our hotline at 1-650-522-7250.
  • You can also visit our UFES project page to see project details and sign up for our e-newsletter. If you don’t want to opt in, but still want information, bookmark the link where we post our updates to the project website.