Throughout the country, there are hundreds of fire training areas where aqueous film-forming foam (AFFF) was applied, resulting in per- and polyfluoroalkyl substance (PFAS) impacts to surface water and groundwater. At many facilities, AFFF release has resulted in egress and diffusion into (and adsorption onto) concrete and asphalt surfaces rendering them potential sources for PFAS leaching. Effective tools are needed to stabilize and mitigate PFAS leaching from AFFF-impacted concrete. Work conducted in Australia on local sites in the last five years has demonstrated the potential for stabilizing agents such as surface and penetrating sealants to cost-effectively mitigate PFAS leaching risks in concrete. These data suggest variability in concrete, environmental conditions, and uses affect sealant performance. As such, standardized methods are needed to rapidly assess the potential for PFAS leaching based on site-specific attributes, such as concrete type, AFFF use, and future use/remedial goals. Studies are also needed to evaluate sealant types and applications to support the selection process and to ensure that methods are compatible with PFAS and resulting data are representative of the risk of PFAS leaching under waste disposal or reuse scenarios.

Accordingly, the overarching goal of this project is to identify and validate the performance of sealants and to develop a framework for evaluating their efficacy to mitigate or stabilize PFAS leaching from AFFF-impacted concrete.

A multi-staged approach will be undertaken using literature review, laboratory, modelling, and field approaches including:

• characterization of AFFF-impacted concrete as leaching sources of PFAS to screen sites for selection and sampling;
• identification and characterization of the physicochemical attributes of a range of sealants at bench-scale as barriers to leaching of PFAS from impacted concrete;
• use of existing or emerging leachate testing protocols to assess PFAS leaching from treated concrete using a range of intact media samples compared to untreated controls and development of a PFAS leaching kinetic predictive model to evaluate the performance of treated media;
• extended trials to determine longevity and efficacy of PFAS sealants; and
• generation of a protocol framework for field evaluation and demonstration of prioritized sealants.

This project will result in information that allows for more informed management of AFFF-impacted concrete, including a framework to use for selection of sealants/combinations. (Anticipated Project Completion - 2025)