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This 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.

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Some of the same unique physical and chemical properties that make per‐ and polyfluoroalkyl substances (PFAS) desirable for a wide range of commercial applications render them recalcitrant to many liquid treatment technologies. As developments in PFAS‐related toxicological studies increasingly suggest potential adverse human health effects, our industry has made great progress in the past several years on concentrating PFAS into small volume waste streams via adsorption and separation mechanisms. Coupled with residual PFAS‐containing commercial products that are being phased out, management of these concentrated waste streams presents an urgent need for the development and validation of destructive treatment technologies. Here, we field‐validate supercritical water oxidation to treat a concentrated waste stream of 12 perfluoroalkyl acids (PFAAs) with liquid and gaseous analysis, adhering to the recent Other Test Method 45 for stack emission sampling from the United States Environmental Protection Agency (USEPA) and USEPA Method 537.1, with quality control and quality assurance protocols from the Department of Defense/Department of Energy Quality Systems Manual 5.3. Results generated suggest greater than 99.999% destruction and removal efficiency of these 12 PFAAs after two ∼120‐min continuous flow trials, with an overall defluorination percentage of approximately 62.6%.

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