Carey, G.R., A.L.-T. Pham, S.G. Hakimabadi, R. McGregor, and B. Sleep.
CRC Care International Cleanup Conference, 8-12 September, Adelaide, Australia, 37 slides, 2019

A remediation model using similar chemical and hydrogeologic conditions at a former fire training area (FTA) simulated the longevity range of an in situ colloidal activated carbon (CAC) remedy in a hypothetical site scenario. The real FTA site was contaminated with ≤ 313 µg/L PFHxS, ≤ 152 µg/L PFOA, and ≤ 74 µg/L PFOS. Two source zones were simulated: a smaller, high-concentration 15 m x 15 m source zone and a larger, lower-concentration 100 m x 100 m source zone surrounding the high concentration zone. The study evaluated the remedy's sensitivity to various PFAS constituent properties, mass discharge rates, length of the CAC barrier, and the in situ CAC concentration. Laboratory-derived isotherms indicated that 1) PFAS sorption affinity to CAC is directly proportional to molecular chain length, with sulfonates having a higher affinity than carboxylates of the same chain length and 2) affinity to CAC is reduced for mixtures of PFAS compounds with high total organic carbon. The presentation also reviews studies on granular activated carbon (GAC) performance with PFAS mixtures relative to CAC implementation. Strategies for incorporating CAC-based mass flux reduction alternatives for managing PFAS sites are discussed, including the benefits and limitations of this remedial approach. Research needs for evaluating factors influencing CAC performance at lab and field scale are presented. http://adelaide2019.cleanupconference.com/wp-content/uploads/2019/09/M22a.pdf