Orange County, California, had long relied on groundwater for most of its drinking water, drawing on a 270-square-mile basin to supply a major West Coast population center. But that changed dramatically in 2019 when state officials mandated testing for PFAS chemicals and set strict new limits for the contaminants.
The action forced the county to shut down about 60 wells and replace lost supply from other state sources and beyond, a move that cost one of its largest communities, the city of Anaheim of more than 350,000, up to $2 million a month and forced a 10 percent annual rate hike on all county users. With that unsustainable response, the district took a different approach: first it launched a record-sized pilot program to test different PFAS treatment processes.
The resulting projects in Anaheim and nearby Yorba Linda are considered the two largest efforts in the US, and Chris Olsen, the district’s executive director of engineering and water resources, is instrumental in their multi-team execution. The district is funding all treatment infrastructure design and construction and is splitting operation and maintenance costs with 19 cities and agencies, he says. “Water is essential to life and I fully support our mission, which is to provide a reliable, high-quality water supply in a cost-effective and environmentally responsible manner,” says Olsen.
Anaheim is completing two key phases of its construction effort, which includes ion exchange with resin technology for 35 separate treatment systems, which necessitated the hiring of CDM Smith as the design and construction lead on the city’s first use of this alternative delivery approach. Four completed plants have a combined capacity to treat 39.2 million gallons per day.
Once fully built in 2027, Anaheim will treat up to 73.2 million gallons per day. “Some locations did not have enough space for new treatment systems, which prompted the DB team to use 3D modeling to minimize plant footprints,” says Jacob Hester, Anaheim’s manager of water engineering. “The program increased the cost of operation by 40 percent, but it is almost half the cost of imported water.”
Olsen says the roughly $28 million, 25-million-gallon-per-day Yorba Linda PFAS plant, on which he was project manager, also uses ion-exchange technology. “It has exceeded expectations” in operation since 2021,” he says. “The life of the resin in the plant is longer than expected, resulting in significant cost savings.”
Tetra Tech led its design and construction management team, with Pacific Hydrotech as the contractor. Olsen says a 3D virtual tour from Tetra Tech allowed Yorba Linda operators to virtually walk through the treatment plant and suggest key design changes, such as the location and access points of piping, fittings and equipment.
According to Olsen, PFAS-related costs will reach $1.8 billion in Orange County over the next 30 years for capital and operations and maintenance costs, involving multiple treatment plants in 10 cities and more than 50 wells. The current federal limits for PFAS in drinking water, set in April 2024, are 4 parts per billion for the chemicals PFOA and PFOS individually. But the Trump administration could change them and also push back the current 2029 compliance deadline for water systems.
The district has allocated $85.2 million for construction of PFAS treatment facilities in the 2025-26 fiscal year budget. To raise the needed investment, the water district has secured $94.4 million in low-interest federal WIFIA loans and more than $120 million in state and federal grants.
The district has also won $78 million in legal settlements so far with PFAS manufacturers that include 3M and Dupont, Olsen says, “with additional payments expected.”
