As part of a JV, Weston conducted a time-sensitive response to install, operate, and maintain an Interim Storm Water Treatment System (ISWTS) to treat storm water contaminated with PFOS/PFOA from prior Aqueous film forming foam AFFF usage. Weston developed and implemented the interim mitigation system to create storm water capacity and to treat surface water that previously connected to a potable water supply, which served 10,000 people. Weston was prepared to respond to weather events around the clock to shut down the system if the water level topped the weir. The mitigation system is comprised of a floating pump, solids pretreatment system, and four treatment trains. Water is pumped from a pond through the pretreatment system and then distributed to four PFOA/PFOS treatment trains before discharge. Treated water can either be recycled to the pond or discharged to an outfall structure. Weston performed initial site reconnaissance; analyzed runoff; developed, procured, and installed an approved mitigation system; developed/implemented ancillary infrastructure required for operation; conducted startup and O&M; performed PFAS analytical monitoring; and supported community outreach. Weekly effluent sampling for PFOS/PFOA have met project goals of being below the discharge criteria and the EPA drinking water lifetime Health Advisory standard of 70 parts per trillion. Weston’s responsiveness and flexibility for being on-call 24/7, 365 days/year to respond to alarms and shut down the system when the water level topped the weir has been recognized by the client.