Application of PFAS‐mobile lab to support adaptive characterization and flux‐based conceptual site models at AFFF releases

Abstract

AbstractThis article presents two aspects of an Environmental Security Technology Certification Program (ESTCP) demonstration conducted at Camp Grayling Army Airfield in Grayling, Michigan: verification of an accelerated per‐ and polyfluoroalkyl substances (PFAS) screening method using liquid chromatography and tandem mass spectroscopy and its application to develop a flux‐based conceptual model. The ESTCP project information can be found here: https://serdp‐estcp.org/Program‐Areas/Environmental‐Restoration/Contaminated‐Groundwater/Emerging‐Issues/ER19‐5203. The objective is to demonstrate the value of adaptive high‐resolution PFAS site characterization using a quantitative screening method that is selective for PFAS compounds and sensitive across the range of concentrations between screening levels at 40 nanograms per liter and source impacts within the milligram per liter range. The reliability of the method is demonstrated using three metrics: sample pair comparability statistics with an Environmental Laboratory Accreditation Program‐certified lab, visual interpretation of characterization and relative flux, and comparison of contaminant mass discharge calculated at flux transects. In addition, the study measured vadose zone source strength using three methods: soil to groundwater concentration ratios, lysimeter porewater sample analysis, and synthetic precipitation leaching procedure testing. The overall results demonstrate that application of the mobile lab and the stratigraphic flux approach can distinguish individual PFAS sources, visually map perfluorooctanoic acid and perfluorooctane sulfonate and migration pathways, and provide an efficient means of ranking source contributions to plumes.