The Zone 7 Water Agency recently unveiled its new state-of-the-art water treatment facility, which will use an ion exchange treatment process to remove PFAS chemicals from the Stoneridge groundwater well in Pleasanton. … Nearly 30 Tri-Valley officials, residents and Zone 7 staff members gathered for the event to celebrate the first-of-its-kind facility in Northern California. Located on Stoneridge Drive just west of Mohr Elementary School, the Ion Exchange PFAS Treatment Facility uses tanks that are filled with small ion-exchange polymers, which are designed to attract PFAS chemicals, otherwise known as forever chemicals, in the water.