Understanding per- and polyfluoroalkyl substance (PFAS) sources and their potential impacts to groundwater and surface water is of critical importance. There are numerous areas where aqueous film-forming foam (AFFF) has been in contact with construction materials such as concrete and asphalt, including fire training pads, hangars, crash sites on runways and taxiways, stormwater drainage systems, and other sites. The objective of this project is to: (1) assess the leaching potential of PFAS, (2) determine the magnitude of PFAS loading that exists within concrete and asphalt, (3) develop methods for in-place management, and (4) understand if PFAS-impacted construction materials can be reused. The overall goal is to increase the understanding of the processes that control the fate and transport of PFAS contained in construction materials, both by collecting a rich array of empirical data and by developing modeling approaches that eventually can be used by remedial project managers to manage their PFAS sites.

First, the project team will conduct a detailed field sampling program to obtain dozens of vertical PFAS concentration profiles in construction materials at 4 to 6 sites. Second, the project team will perform diffusion, leaching, and transformation experiments using the specialized laboratory analytical, diffusion, and testing equipment at Colorado State University. The synthesis of these two activities will generate a unique dataset that will allow the project team to develop simple predictive models of how PFAS invades construction materials and the rate at which PFAS are released into the environment (Figure 1). With these models, site managers will be able to transform readily collected data from their site and then simulate/understand the PFAS transport life cycle into and out of AFFF-impacted construction materials. This analysis, in turn, will allow site managers to evaluate a broad array of management strategies, such as leaving the PFAS in place, applying sealants, or re-using the materials.

The project team anticipates that by developing useful empirical datasets and models of the transport mechanisms of PFAS in construction materials, the most successful and cost-effective management approaches can be effectively developed for any specific AFFF site. This research will provide a clearer roadmap for determining when PFAS-impacted construction materials are a problem, and if so, how to reduce the environmental impact of these materials. (Anticipated Project Completion - 2025)