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This SERDP and ESTCP webinar focuses on DoD-funded research efforts to better understand and remediate DoD sites impacted by per- and polyfluoroalkyl substances (PFAS). Specifically, investigators will cover experiments to improve understanding the persistence of PFAS source zones in areas of historical aqueous film forming foams (AFFF) usage, as well as the results of a recent pilot test to reduce PFAS mass in source zones using In-Situ Foam Fractionation (ISFF).
“A Mechanistic Understanding of PFAS in Source Zones: Characterization and Control” by Dr. Jennifer Field ( SERDP Project ER18-1259)
This presentation will discuss how data collected during this project aids in understanding the development and persistence of PFAS source zones in and around areas of historical AFFF usage. The main objectives of this SERDP effort are to ascertain PFAS interactions with soils and sediments under saturated conditions using AFFF at application strength, determine the number of thermodynamically stable phases that form when AFFF at application strength mixes with fuels such as jet fuel (specifically, Jet Fuel A), and quantify PFAS at the air-water interface and its impact on transport under unsaturated conditions. Column experiments revealed that soil horizons with little organic matter retained greater amounts of PFAS than predicted by existing organic carbon-water partition coefficients. Laboratory batch and column experiments indicate that when AFFF and Jet Fuel A mix, a viscous microemulsion forms and retains a significant fraction of PFAS and becomes immobile. PFAS transport under unsaturated conditions in the laboratory is described by concentration-dependent Freundlich model and is a function of PFAS hydrophobicity with retention even for short-chain PFAS.
“In-Situ Foam Fractionation: Harnessing the Power of Bubbles to Remove PFAS from Plumes and Source Zones” by Dr. David Reynolds (ESTCP Project ER19-5075)
ISFF is a promising remediation technology that effectively removes PFAS mass by introducing bubbles to the source zone or plume through treatment wells that concentrate PFAS in a foam at the water table for subsequent vacuum extraction. The project’s objectives focus on demonstration of the technology with a particular emphasis on its ability to concentrate PFAS, the required maintenance levels of the system, and the radius of influence of each treatment well. This presentation will cover a recent pilot test of In-Situ Foam Fractionation (ISFF) removal of PFAS mass from the core of a high-concentration plume. The pilot ISFF system was operated for a period of 15 weeks (using two treatment wells) and removed a total of 40 g of PFAS. The pilot test achieved PFAS concentration reductions of up to 96% in groundwater and 94% in soil with no chemical additives, heating, or groundwater extraction for treatment. A sample of the recovered high concentration fluid was successfully treated to non-detect (for PFAS) via hydrothermal treatment at the Colorado School of Mines. ISFF offers the DoD an alternative to pump and treat approaches that reduces operational costs and minimizes the generation of a secondary waste stream.
Dr. Jennifer Field is a professor in the department of environmental and molecular toxicology at Oregon State University in Corvallis, Oregon. Her current research focuses on the analytical chemistry, fate, and transport of PFAS. She serves as the principal investigator of several SERDP and U.S Environmental Protection Agency research grants evaluating the fate and transport of PFAS in groundwater impacted by AFFF and municipal landfills. She has authored 130 peer-reviewed research papers. Dr. Field received a bachelor's degree in environmental science from Northland College in Ashland, Wisconsin, and a doctoral degree in geochemistry from the Colorado School of Mines in Golden, Colorado.
Dr. David Reynolds is a senior principal engineer with Geosyntec Consultants based in Australia. As a contaminated sites auditor in Western Australia and Queensland, his work focuses on transitioning remediation concepts to practice, as well as the value of information in site assessment and remediation design. He is the co-inventor of electrokinetic oxidation approaches for remediation of heterogeneous and low permeability source zones, as well as the use of electromigration for in-situ desalination. Dr. Reynolds has previously served as a research director at the Centre for Groundwater Research, a senior technical advisor at two international consulting companies, and as a senior lecturer at the University of Western Australia. He received a bachelor’s degree in geological engineering from the University of Waterloo in Canada and his master’s and doctoral degrees in geological engineering from Queen’s University, also in Canada.