Toxic chemicals have been leaking into the groundwater under and around the San Luis Obispo County Regional Airport for about five decades. It’s not the only airport in the state dealing with this contamination, but it is the first to address the problem with a formal plan. That’s because the contamination impacted dozens of private wells for homes and businesses. Many affected residents feel like the process is moving too slowly. … But the foam is full of harmful chemicals called per- and polyfluoroalkyl substances, or PFAS. They’re often called “forever chemicals” because they don’t break down in the environment. … Beginning in 2019, the State Water Board ordered 30 airports in California to investigate PFAS contamination. According to the board, all of them showed some level of impact. As for the SLO airport, a vast majority of the more than 70 wells in the area were contaminated.