Mocho PFAS Treatment Plant

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Mocho Wellfield PFAS Treatment Facility

In a continuing effort to supply the Tri-Valley with safe, reliable water that meets state and federal drinking water standards, Zone 7 is planning the Mocho PFAS Treatment Plant to address Per- and Polyfluoroalkyl substances (PFAS) found in the local groundwater at its Mocho wellfield. 

ABOUT THE PROJECT

  • The Mocho PFAS Treatment Plant will enable Zone 7 Water Agency to:
    • Remove PFAS from the Mocho wellfield
    • Restore the Mocho wellfield production capacity and operational reliability to meet current and future water supply needs
    • Increase Mocho Groundwater Demineralization Plant’s ability to remove salt in the groundwater basin
  • The plant will be the third of Zone 7’s infrastructure projects focused specifically on removing PFAS from its groundwater supplies, joining the Stoneridge PFAS Treatment Plant that became operational in September 2023 and the Chain of Lakes PFAS Treatment Plant that became operational in April 2025.
  • Like the Stoneridge and Chain of Lakes PFAS Treatment Plants, the Mocho plant will use ion exchange, identified by the U.S. Environmental Protection Agency as a best available treatment for PFAS removal.
  • The anticipated cost of this project is $35-$51 million. 
    • Zone 7 was awarded a grant for $1.2 million from the California Department of Water Resources and is actively working to secure additional state funding as well as federal funding for this project.
  • The plant will be constructed at Zone 7’s existing Mocho Well 3 facility near Santa Rita Road and Stoneridge Drive within the City of Pleasanton, just south of the existing Mocho Groundwater Demineralization Plant. 
  • Mechanical and electrical improvements will also occur at the Mocho well sites and Mocho Groundwater Demineralization Plant, near Santa Rita Road and Stoneridge Drive. 
  • Additional public engagement and outreach will take place prior to construction.
  • Download our general one-sheet to get an overview of the new facility. Mocho PFAS General One-Sheet

Proposed Mocho PFAS Treatment Plant

Proposed Mocho PFAS Treatment Plant

PROJECT NEED

  • In 2018, while state and federal agencies were still developing guidance and regulations, Zone 7 voluntarily initiated proactive monitoring for PFAS and reduced production in select wells with elevated PFAS levels. 
  • The operational capacity and reliability of the Mocho wellfield has been significantly reduced, and this project will restore that capacity and reliability. 
  • The Livermore Valley Groundwater Basin, where this project is located, plays a critical role in providing reliable water for the Tri-Valley, especially during droughts. 
  • PFAS treatment infrastructure investments are an integral element of our safe and sustainable long-term water supply strategy for the Tri-Valley.

PROJECT SCHEDULE & UPDATES

  • In order to restore the production capacity and reliability of the Mocho wellfield as quickly as possible, a schedule-saving alternative project delivery combining both design and construction, known as progressive design-build, will be used. 
  • The project is in the planning and preliminary environmental review phase.
  • Award of the contract to design the facility is anticipated for early 2026.
  • Construction is anticipated to begin in late 2026.

CONTACT OUR PROJECT TEAM

We appreciate your patience throughout the project as we make these important improvements to your water treatment system. Questions? Concerns?

Please email mtp@zone7water.com 

LEARN MORE ABOUT PFAS

  • All water supplied to our customers meets the regulatory standards set by the state and federal governments. 
  • In almost all cases, the quality was significantly better than required. 
  • Zone 7 continues to deliver all water below the California Division of Drinking Water’s response levels for PFAS.
  • For more information about how we keep your water safe from PFAS click here.