Release of perfluoroalkyl substances from AFFF-impacted concrete in a firefighting training ground (FTG) under repeated rainfall simulations

Historical use of per- and polyfluoroalkyl substances (PFAS) at firefighting training grounds (FTGs) has prompted questions regarding possible PFAS retention within concrete and subsequent releases to the environment. This investigation seeks to better understand the release of five PFAS from concrete cores collected from a legacy FTG. The vertical profile of cores were assessed, then surface ponding and rainfall simulations were conducted on the cores. Perfluorooctane sulfonate (PFOS) had the highest concentrations in both the core (up to 10,000 μg kg−1) and in ponded water on their surface (up to 100 μg L−1), followed by 6:2 fluorotelomer sulfonate (6:2 FTS) and perfluorohexane sulfonate (PFHxS). The maximum concentrations of PFAS in runoff water of five rainfall simulations were similar, suggesting recurring release of PFAS from AFFF impacted concrete, which could be sustained by upward transport of PFAS in the concrete subsurface layers through a potential “wicking” effect. The estimated mass of PFAS released during a simulated rainfall of 60 mm was approximately 1% of the total PFAS mass estimated within the top 1 cm of the concrete core. The results of the study suggest that concrete at FTGs may present an ongoing secondary source of PFAS in runoff water events.