Underground Flow Equalization System (UFES)

PA18-010 - Site Plan

Project Description

The City of San Mateo is implementing a series of capital projects, referred to collectively as the Clean Water Program (CWP), to replace aging wastewater infrastructure, build wet weather capacity, comply with regulatory requirements, and align with the City’s sustainability goals. In adopting the 2016 Final Program EIR for the CWP, the City Council selected the “In-System Storage Program” alternative. The Underground Flow Equalization System (UFES) project, consistent with the Council’s selected program alternative, will provide the wastewater system capacity to comply with regulations requiring prevention of sanitary system overflows.

  • This project consists of a concrete holding structure, pump station, diversion sewers and force main, and on odor control equipment room. These facilities would be located underground. Access hatches, an emergency backup generator, and an electrical building and vents for treated air would be located at ground level.
  • The proposed project will provide for short-term storage of wastewater to prevent sanitary sewer overflows during wet weather.
  • On July 17, 2017, the City Council selected the San Mateo County Event Center parking lot as the preferred location for the project.

Project Update

A Final Environmental Impact Report (Final EIR) has been prepared to specifically identify and analyze the anticipated environmental impacts of the Underground Flow Equalization System (UFES) project. The Final EIR includes responses to the comments received on the Draft EIR, as well as any amendments needed to the Draft EIR in response to comments.  The project will require a Special Use Permit for a public service use in the “A” Agricultural District and a Site Plan & Architectural Review (SPAR) for structures and walls over six feet in height.

  • On September 24, 2019, the City of San Mateo Planning Commission recommended City Council approval of the Special Use Permit, Site Plan and Architectural Review and certification of the Final EIR. This included the Mitigation Monitoring and Reporting Program and adoption of a Statement of Overriding Considerations regarding construction noise impacts.
  • On October 21, 2019, by vote of 5-0, the City Council held a Public Hearing and adopted the Resolution to approve the City of San Mateo Underground Flow Equalization System, certify the final Environmental Impact Report, and adopt California Environmental Quality Act Findings, Statement of Overriding Considerations, and Mitigation Monitoring and Reporting Program.

Related Documents


  • City Council (Public Hearing): Meeting Materials & Video – October 21, 2019
  • Planning Commission (Public Hearing): Meeting Materials & Video – September 24, 2019
  • Planning Commission (Study Session): Meeting Materials & Video – August 27, 2019
  • Planning Commission (Study Session): Meeting Materials – April 9, 2019
  • Planning Commission (Study Session): Meeting Video – April 9, 2019
  • Community Meeting: – May 21, 2019
    (The Clean Water Program hosted a community meeting about the project and the Draft Environmental Impact Report with time for questions and answers. The meeting was held at the San Mateo County Event Center.) 

Applicant Information

Clean Water Program
City of San Mateo
Public Works Department

City Contact Information

Julia Klein
Principal Planner
(650) 522-7216