Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7h2. PFAS Fate and Transport in Surface Water

Formatted Title:

Characterization of Per- and Polyfluoroalkyl Substances in Stormwater and Evaluation of Fate and Transport of PFAS in Stormwater Management Systems

Background/Objectives:

As point source treatment and management has improved, non-point source stormwater is increasingly a concern for contamination of waterways and sediments. The rapid expansion of urban areas and increased impervious surfaces lead to higher stormwater volumes and contaminant loads. However, treating stormwater presents challenges due to variable contaminant loads, event-driven factors, and cumulative effects over time. Moreover, the sediment impacts of stormwater are a strong function not only of the total contaminant load but also of how it is distributed onto particles of different sizes and settling rates. In this study, we seek to better understand the characterization of per- and polyfluoroalkyl substances (PFAS) compounds in stormwater. Additionally, we evaluate the performance of existing stormwater management systems at various DoD sites for the removal of PFAS.

Approach/Activities:

Stormwater was collected from several DoD sites employing stormwater management systems, including retention pond, bioswale, bio & media filter, and hydrodynamic separator and cartridge filter. Stormwater samples were collected from three outfalls (for retention pond), and inlet and outlet of stormwater management systems for multiple storm events for each DoD site. For retention pond, water samples were collected from the north and south sides of the pond for prestorm, poststorm, and monthly for long-term monitoring. The collected stormwater samples were size fractioned to determine the concentration associated with different particle fractions (broadly classified as clay, silt, and sand) and dissolved fractions. The samples were analyzed for PFAS via high-performance liquid chromatography (HPLC) coupled with a Sciex X500R quadrupole time of flight mass spectrometer (QToF) following EPA Method 1633.

Results/Lessons Learned:

The results indicate that stormwater was responsible for the mobilization of PFAS from the source area. The size-based characterization of stormwater reveals that most of the measured PFAS is associated with the dissolved fraction of stormwater except for relatively stronger sorbing PFAS (e.g., PFOS, PFOSA), which had a considerable association with stormwater solids. The long-term sampling of the retention pond indicated that PFAS compounds associated with the dissolved phase can be modeled by changes in volume due to accumulation in the retention pond. In contrast, particle-associated PFAS compounds suggested additional losses due to settling or partitioning behavior. All of the BMPs were effective in removing coarse solids but performed poorly in the removal of PFAS. The results emphasize the need for improved stormwater management strategies to address PFAS contamination.

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David Sackey