The overall goals of this project are to evaluate the leaching of per- and polyfluoroalkyl substances (PFAS) from construction materials impacted by the discharge of aqueous film-forming foam (AFFF) onto impervious surfaces and to investigate the potential benefits of using amendments in re-used concrete and asphalt materials to reduce PFAS leaching to surface and ground waters. This project will significantly advance the understanding of the relative PFAS leaching potential from concrete and asphalt as well as the impact of construction material degradation on PFAS leaching. The project team posits that the extent of construction material degradation due to historical climatic conditions and/or excessive loading will significantly impact the release of PFAS from concrete and asphalt materials. Further, the project team hypothesizes that adding amendments to re-used concrete and/or asphalt will significantly reduce PFAS leaching from these materials, thereby increasing the fraction of AFFF-impacted concrete and/or asphalt that could be re-used for a given site. The project team also posits that stormwater pollutant wash off modeling can be calibrated to support accurate estimation of runoff concentrations, mass loading, and longevity of export from impacted and amended construction materials.
Using field-collected and AFFF-impacted intact cores of concrete and asphalt from at least three distinct sites representing a range of material degradation, the project team will evaluate the role of material degradation on the extent of PFAS releases. After initial characterization of the PFAS concentration profiles within the collected cores, laboratory leaching experiments (using standardized protocols) will enable the development of PFAS-specific release concentration profiles and subsequent calculations of the fractional mass released of each PFAS per storm event. Using the same or similar materials that are subsequently crushed or crushed and re-formed into new materials, the project team will evaluate the role of the physical state and pore connectivity of the AFFF-impacted construction materials on PFAS release. A subset of concrete samples will also be pre-treated with surface or penetrable sealants being evaluated under a separate project to assess the impact of sealants on the leachability of PFAS from concrete upon re-use. The project team will also evaluate the extent to which different amendments added to re-formed materials can reduce PFAS leachability. Finally, the project team will evaluate the potential loadings of PFAS from intact versus crushed versus reformed materials to receiving surface water bodies.
Successful completion of this research will information on the leaching potential of AFFF-impacted concrete and asphalt. At a minimum, this information could inform decisions related to disposal of impacted construction materials. An evaluation of PFAS leaching from intact versus crushed versus reformed materials will also enable scientifically defensible decisions about beneficial re-use of PFAS-impacted construction materials. Such information, when coupled with modeling of PFAS concentrations, mass loading, and longevity of export from impacted materials, will be critical to future discharge compliance assessments as well as quantifying receiving water impacts and risks to human and aquatic ecological receptors. Coupling these data and modeling approaches with site-specific information will ultimately ensure that robust management decisions are made with respect to identifying remediation, re-use, and/or disposal options for PFAS-impacted concrete and asphalt at DoD facilities. (Anticipated Project Completion - 2026)