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Presentation Slides

This SERDP and ESTCP webinar focuses on DoD-funded research to quantify PFAS leaching at AFFF-impacted sites. Specifically, investigators will present efforts to develop a standard PFAS leaching assessment methodology by optimizing three standard leaching methods, as well as research into the relationship between PFAS concentrations measured in soil and those measured in porewater with the ultimate goal of facilitating site management. 

Abstracts

 “Development and Validation of Novel Techniques to Assess Leaching and Mobility of PFAS in Impacted Media” by Dr. Jennifer Guelfo (SERDP Project ER20-1126) 

To effectively prioritize sites impacted by PFAS for further investigation and/or remediation, standardized tools are needed to rapidly assess PFAS retention, leaching and transport from the source zone to downgradient regions. Standard leaching methods in EPA SW-846, known as the Leaching Environmental Assessment Framework (LEAF; EPA Methods 1313–1316), were originally developed for inorganic constituents and need to be optimized and validated for PFAS. To meet these needs, a primary objective of ER20-1126 is to develop a standard leaching assessment methodology for aqueous film forming foam (AFFF)-impacted media. Methods 1313, 1314 and 1316 have been optimized and demonstrated using four AFFF-impacted soils. This presentation will compare these three methods, discuss approaches to optimizing them for PFAS, and compare the method results and replicability. Consistency between the LEAF methods implemented on AFFF-impacted soils were similar to what has been observed in prior studies for inorganic constituents. Future work will evaluate LEAF estimates of PFAS leaching and mobility to PFAS releases (i.e., leaching source terms) observed in the field. 

“PFAS Leaching at AFFF-Impacted Sites: Insight into Soil-to-Groundwater Ratios” by Dr. Charles Schaefer (ESTCP Project ER20-5088) 

This ongoing ESTCP project supports the DoD’s efforts to understand the risks associated with the leaching of PFAS from soils that have been impacted with AFFF. Specifically, this research explores the relationship between PFAS concentrations measured in unsaturated soils and PFAS concentrations in mobile porewater that could potentially migrate to underlying groundwater, with the ultimate goal of facilitating site management. The roles of both kinetics and phase equilibria are examined using a field-based approach that uses porous cup suction lysimeters coupled with bench-scale testing on AFFF-impacted soils. This research focuses on assessing the practical limits of lysimetry at AFFF source areas with varying characteristics and developing approaches for selecting appropriate soil cleanup criteria. This presentation investigates the nature of the PFAS in porewater and discusses potential impacts to conceptual site models. 

Speaker Biographies

Dr. Jennifer Guelfo is an Assistant Professor and an Edward and Linda Faculty Fellow in the Civil, Environmental and Construction Engineering Department at Texas Tech University. She joined Texas Tech University in 2018 following a postdoctoral appointment in the Brown University School of Engineering. For the past 13 years, her research has focused primarily on PFAS occurrence, fate and transport. In addition to academia, she also has a combination of consulting and industry experience, and she uses this background to inform policy and bridge gaps between research and practice. Dr. Guelfo has a bachelor’s degree in geology from the College of Charleston, a master’s degree in environmental science and engineering from the Colorado School of Mines (CSM), and a doctoral degree in hydrologic science and engineering from CSM. 

Dr. Charles Schaefer is the Director of CDM Smith’s Research and Testing Laboratory in Bellevue, Washington. He has over 25 years of experience in evaluating the fate, transport and treatment of organic contaminants in water, soil and fractured rock. Dr. Schaefer has served as a principal or co-principal investigator for research projects funded by SERDP, ESTCP, the Air Force Civil Engineering Center, the Navy Environmental Sustainability Development to Integration Program and the Water Research Foundation. He has authored over 90 peer-reviewed publications and has been awarded the SERDP/ESTCP Project of the Year three times as either a principal investigator or co-principal investigator. In addition, Dr. Schaefer has served as the technical lead on several site investigation and remedial efforts supporting state, municipal, industrial and federal clients. He received his undergraduate and doctoral degrees in chemical and biochemical engineering from Rutgers University.