The increased focus on per- and polyfluoroalkyl substance (PFAS) impacts to groundwater and soil has led to closer scrutiny of potential impacts of historic PFAS-containing aqueous film-forming foam (AFFF) usage and/or from the intrusion and infiltration of impacted groundwater to stormwater systems. This project will research three inter-related hypotheses regarding the management of PFAS-impacted stormwater:

• Hypothesis 1: Detailed intra- and inter-storm stormwater sampling will identify key high-concentration “slivers” of PFAS-impacted stormwater loads such as first flush effects, PFAS on suspended solids, and/or PFAS at air and water interfaces that can be easily separated to reduce the cost and complexity of treatment.

• Hypothesis 2: Simple to mid-level stormwater nonpoint source models can extend sampling datasets and reduce the amount of sampling required to quantify PFAS loads in stormwater and select site-specific treatments.

• Hypothesis 3: The most useful PFAS stormwater management technologies will be adaptations of existing practices, methods, and technologies from the stormwater field for non-PFAS and/or groundwater PFAS treatment technologies, as opposed to new technologies specifically targeted at PFAS in stormwater.

By understanding the nature of the PFAS mass loadings both temporally and spatially, it may be possible to significantly reduce the magnitude of the PFAS stormwater problem and just focus treatment on a small subset of the most critical PFAS stormwater transport compartments. 

The experimental design of this research is modeled after the successful history of the nonpoint source pollution field, where a portfolio of intra- and inter-storm stormwater sampling data, selected on-site data, and simple runoff loading models have enabled the current design and use of stormwater treatment systems at industrial sites. For this project, the research team will design and then conduct detailed stormwater sampling at a AFFF-impacted site over one year and survey a single storm at other facilities. These data will be interpreted and extended by using simple to mid-level stormwater nonpoint source loading models.

To evaluate the three hypotheses, the project team will complete several tasks including composing a detailed literature review, undertaking detailed stormwater sampling at up to 5 DoD sites and up to 20 discrete storm events and applying stormwater runoff models to provide better estimates of key treatment design variables. The data will be used to synthesize existing knowledge regarding PFAS properties and industrial stormwater treatment to develop hybrid designs for PFAS-impacted stormwater, and performing small-scale testing of relatively simple treatment approaches at an actual field site.

With these resulting PFAS stormwater loading data, useful and cost-effective treatment alternatives can be identified from portfolios of existing stormwater treatment methodologies, groundwater treatment technologies, or integrated approaches. The project envisions that new knowledge about a wide range of PFAS stormwater strategies, such as isolating sub-basins, the viability of first flush treatment, sealing/capping PFAS-impacted materials, if and how to employ sedimentation basins, and approaches for active treatment of stormwater streams that require PFAS removal. (Anticipated Project Completion - 2026)