Evaluation of sealants to mitigate the release of per- and polyfluoroalkyl substances (PFAS) from AFFF-impacted concrete: Characterization and forecasting

• Published in: Water research X 2023-09, Vol.20, p.100195-100195, Article 100195
• Main Authors: Vo, Phong H.N., Key, Trent A., Le, Tu Hoang, McDonough, Jeffrey T., Porman, Scott, Fiorenza, Stephanie, Nguyen, Hong T.M., Dao, Vinh T.N., Mueller, Jochen F., Thai, Phong K.
• Format: Article
• Language: English
• Subjects: AFFF; Concrete; PFAS; Runoff modeling; Surface sealant
• ISSN: 2589-9147; 2589-9147
• DOI: 10.1016/j.wroa.2023.100195

•Product B (organic-based sealant) is more effective than product A (inorganic-based sealant).•PFOS cumulative mass loss of unsealed pad reaches to steady state after 15 years (∼400 mg/m2).•85% of PFOS mass has been leached from the product A-sealed pad after 20 years (340 mg/m2).•PFOS cumulative mass loss from the product B-sealed concrete pad is negligible (5 × 10−9 mg/m2). Per- and polyfluoroalkyl substances (PFAS) within concrete pads impacted by historical firefighting training using aqueous film-forming foam (AFFF) may be potential secondary sources of PFAS due to surficial leaching. This study aimed to (i) characterize the effectiveness of two commercially available sealants (Product A and Product B) in mitigating leaching of five PFAS (e.g., PFOS, PFOA, PFHxS, PFHxA, 6:2 FTS) from concrete surfaces at the laboratory-scale, and (ii) develop a model to forecast cumulative leaching of the same five PFAS over 20 years from sealed and unsealed concrete surfaces. Laboratory trials demonstrated that both sealants reduced the surficial leaching of the five PFAS studied, and Product B demonstrated a comparatively greater reduction in surface leaching than Product A as measured against unsealed controls. The cumulative PFOS leaching from an unsealed concrete surface is estimated by the model to be about 400 mg/m2 over 20 years and reached asymptotic conditions after 15 years. In contrast, the model output suggests asymptotic conditions were not achieved within the modeled time of 20 years after sealing with Product A and 85% of PFOS was predicted to have leached (∼340 mg/m2). Negligible leaching of PFOS after sealing with Product B was observed ( < 5 × 10−9 mg/m2). Results from modeled rainfall scenarios suggest PFAS leachability is reduced from sealed versus unsealed AFFF-impacted concrete surfaces. [Display omitted]