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Designing Per-and Polyfluoroalkyl Substances (PFAS) Treatment Facilities

Aerial view of the partially below grade 4.0 MGD Serrano Water District PFAS Plant showing the exterior screen walls
Tetra Tech worked with the Orange County Water District (OCWD) to develop treatment systems to remove PFAS from groundwater wells to provide clean, safe drinking water.

In February 2020 California established advisory response levels for two PFAS compounds, and as a result, more than 40 wells were taken out of service due to PFAS contamination. Tetra Tech provided design, permit assistance, and construction management services for three OCWD water agencies: City of Fullerton, Serrano Water District, and Yorba Linda Water District (YLWD), helping to restore critical drinking water sources for thousands of California residents.


  • Designed the largest ion exchange plant treating PFAS in the United States
  • Designed PFAS treatment systems that enabled 10 PFAS contaminated wells to resume service
  • Completed design and construction of Orange County’s first PFAS plant in only 13 months

Our work included designing the largest ion exchange plant treating PFAS in the United States—a first-of-its-kind treatment facility consisting of 11 ion exchange systems, a 25-million gallon-per-day (MGD) booster pump station, and an upgraded onsite chlorine generation system. The YLWD headquarters plant now runs as the largest ion exchange plant treating PFAS in the United States.

Tetra Tech designed extensive new facilities, which were required to be constructed on an existing operating site. Additionally, our experts provided new electrical and gas services to meet county requirements. Tetra Tech initiated the design in May 2020 and the plant began producing water on December 21, 2021.

Environmental Business Journal recognized Tetra Tech with a Project Merit Award for supporting OCWD in developing PFAS treatment systems to purify groundwater that meets California advisory levels for drinking water.

Tetra Tech has done a great job of providing high-quality PFAS treatment designs in a short period of time and has proven to be flexible and responsive in dealing with requested changes throughout the process.  It has and continues to be a successful partnership.

Chris Olsen, Director of Engineering for OCWD
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