STANDING ON TOP of the largest groundwater well in eastern Alameda County, and flanked by twenty-foot cream-colored water vessels, five board members of the Zone 7 Water Agency, a water wholesaler for the tri-valley, have cut the ribbon on an advanced groundwater treatment facility in Pleasanton. 

Zone 7 Water Agency’s board members cut the ribbon during the unveiling of the new Ion Exchange PFAS Treatment Facility at the Stoneridge groundwater well in Pleasanton on Sept 13, 2023. (Ruth Dusseault/Bay City News)

The new technology is called Ion Exchange, which uses positive and negative particles to remove PFAS from ground water. 

PFAS, or polyfluoroalkyl substances, are widely used, long-lasting chemicals, the components of which break down very slowly over time. Thousands of different PFAS are found in many different consumer, commercial, and industrial products, like hiking gear and non-stick cookware.

According to Zone 7, the new system at the Stoneridge Well in Pleasanton is the first of its kind in Northern California, but it will not be the last.

The Stoneridge Well provides 25 percent of the total groundwater production for the Zone 7 district, which includes Pleasanton, Livermore and the Dublin and San Ramon region. About 15 percent of the water goes to agriculture, wine growers and olive orchards in Livermore Valley.  

In Pleasanton, they have three contaminated wells that are shut down right now, said the city’s Mayor, Karla Brown.   

There are also three other Zone 7 wells shut down for PFAs in an unincorporated county east of El Charro called the Chain of Lakes. Similar treatment facilities are planned for those wells, said Valerie Pryor, general manager for Zone 7, and a contract has been awarded.  

The price tag for the new Stoneridge facility was $16.3 million, with $16 million coming from the California Department of Water Resources through a grant Sustainable Groundwater Management Act

Hazards posed by ‘forever chemicals’

In 2022, the clean water watchdog organization Riverkeeper Alliance found PFAS present in most of the surface waters of the United States. Since 2021, the U.S. Environmental Protection Agency has enacted new strategies for addressing the chemicals, including measuring their presence and proposing new policies to safeguard the public.  

Exposure to some PFAS may be linked to harmful health effects, according to the EPA. Because of their widespread use and persistence, PFAS are found in the blood of people and animals all over the world.   

Troubles for the tri-valley region began October 31, 2022, when Zone 7 found high enough levels of PFAS in the area’s groundwater for the board of directors and the city of Pleasanton to voluntarily shut the wells. 

Mayor Mahoney said the well was shuttered during the drought and the city began thinking about treatment systems that could remove the harmful PFAS.   

“This is the culmination of that project,” she said. 

The new Ion Exchange PFAS Treatment Facility at the Stoneridge groundwater well in Pleasanton unveiled on Sept. 13, 2023. (Ruth Dusseault/Bay City News)

Zone 7 is contracting with a company that specializes in the disposal of PFAS once they are filtered out, which could happen every twelve to eighteen months.  

Zone 7 General Manager Pryor said her agency uses a mix of groundwater and surface water to supply clean water to the region. When it’s rainy, they distribute surface water, which has not tested positive for PFAS chemicals.    

“During a dry year, everybody can be getting water from the wells,” said Pryor.   

Zone 7 monitors have found no sole source of the pollution, they said. In addition to urban sprawl and nearby agricultural lands, the residential city of Pleasanton is wrapped around several quarries, and it lies eight miles from the Lawrence Livermore National Lab, which historically tested nuclear and chemical weapons.  

“There are some toxic sites around the lab, but we’ve been monitoring them, and they are contained,” said Pryor. “It’s just the forever chemical. It’s in your pizza box. It gets in the air. It’s in rainwater.”