Clean Water Program LogoCity of San Mateo LogoCity of Foster City LogoCity of San Mateo Public Works Logo


Underground Flow Equalization System

UFES Schedule Update – May 1, 2023

UFES Project Schedule for May 1, 2023 – June 5, 2023

We’re making great construction progress toward pollution prevention in San Mateo. The current rainy season reminds all of us why our 10-year, $1 billion Clean Water Program is so essential to the future of our City.

One of the most important projects in the program is our Underground Flow Equalization System (UFES).

As a follower to this newsletter, you already know that construction is underway on our UFES at the County Event Center. Once completed, our UFES will eventually be the underground 5.3-million-gallon structure that will temporarily hold excess wastewater during storms.

The following construction work is planned for the UFES project from May 1, 2023 through June 5, 2023. (Please note, schedules can change. We will issue this update in the first full week of every month throughout 2023):

  • Inside the Event Center Site: The large concrete pours are complete; however, some of the smaller planned concrete pours may require after-hours approval.
  • S. Delaware Street: Equipment installation and removal related to pipeline work will continue. Motorists should be alert for traffic changes at the intersection of S. Delaware Street and Saratoga Drive due to pipeline work in the vicinity of the Diversion Structure.
  • Saratoga Drive: Lane closures for Saratoga Drive in the vicinity of the San Mateo County Event are in place. Please watch for signs indicating traffic pattern changes.

Alerts will be sent via newsletter and text message ahead of work requiring traffic updates, work hour changes, or expected to generate excess noise at the Event Center site.

Don’t miss an alert. Sign up today for FREE text alerts here or text the word UFES to 1-833-321-0231.

The majority of UFES-related pipeline work and resulting traffic impacts along South Delaware Street and Saratoga Drive are expected to be complete in Spring 2023; however, minor traffic inconveniences in this vicinity may continue through Summer 2023. The City anticipates that the UFES project in its entirety, including work at the San Mateo County Event Center, will conclude by the end of 2023. Once the project is complete, it will be able to reduce the sanitary sewer overflows that result from excessive rainfall, which the community may have witnessed during the recent storms.

For questions or concerns, please contact the UFES hotline at 1-650-522-7250 or email us at

We thank you for your continued patience and cooperation. Visit our UFES page for complete project details.