Presented on August 13 2026 | Download Presentation Slides

Abstract

“Side-by-Side Evaluation of Field-Scale Treatment of PFAS-Impacted Sediments” by Dr. Christopher Higgins, Ms. Elisabeth Hawley, Dr. Conrad Pritchard, and Dr. Hannah McIntyre (ER23-8372) 

 This presentation will spotlight a comprehensive evaluation of multiple treatment technologies through side-by-side field demonstrations designed to remove and destroy PFAS in impacted sediments and ponded stormwater. Sediment treatment technologies included smoldering combustion, thermal desorption, and sediment washing using high-shear mixing with an ethanol co-solvent. Liquid generated during sediment washing was combined with ponded stormwater and treated using surface active foam fractionation (SAFF). Concentrated PFAS foam fractionate was subsequently treated using hydrothermal alkaline treatment (HALT), supercritical water oxidation (SCWO), and ultraviolet-activated photocatalytic silica-based granular media (UV/SGM). This presentation will discuss treatment performance, PFAS removal and destruction, residual PFAS leachability, potential air emissions, field implementation considerations, and costs. Results provide DoW decision-makers with data needed to evaluate treatment options and support more informed, scalable, and cost-effective remediation of PFAS-impacted sediments at military installations.  

Speaker Biographies

Dr. Christopher Higgins is the AMAX Chair in the Civil and Environmental Engineering Department at the Colorado School of Mines in Golden, Colorado. Since joining Mines in 2009, Chris has conducted research on the movement of contaminants in natural and engineered systems, with a particular focus on the fate and transport of PFAS. He  has led research projects supported by the Department of War, National Science Foundation, National Institutes of Health, U.S. Environmental Protection Agency, and U.S. Department of Agriculture. Chris received the American Society of Civil Engineers’ 2019 Huber Prize in Civil Engineering Research and was named a University Distinguished Professor in 2022. He has authored more than 175 peer-reviewed publications. Chris received a bachelor’s degree in chemistry from Harvard University and master’s and doctoral degrees in civil and environmental engineering from Stanford University.

Ms. Elisabeth Hawley is a principal and registered professional engineer at Geosyntec Consultants, Inc. in Oakland, California. Elisabeth has 20 years of experience advancing environmental investigation and remediation projects, with a primary focus on PFAS and other chemicals of emerging concern. She has led PFAS site investigations, background studies, conceptual site model evaluations, and assessments of contaminant sources and fate and transport processes. Elisabeth has also evaluated and implemented PFAS treatment technologies and helped clients navigate technical and regulatory challenges. Through applied research funded by SERDP and ESTCP, Elisabeth recently developed guidance on multiple lines of evidence to assess PFAS treatment effectiveness and evaluate potential sampling bias. She received a bachelor’s degree in environmental engineering and a master’s degree in civil and environmental engineering from the University of California, Berkeley.

Dr. Conrad Pritchard is an Assistant Professor in the O’Neill School of Public and Environmental Affairs at Indiana University in Bloomington, Indiana. Conrad leads a research program that uses advanced analytical chemistry techniques, including high-resolution mass spectrometry, to detect and quantify trace organic contaminants in a variety of environmental media. He also studies the presence and movement of contaminants in the environment, with a focus on the occurrence, fate, and transport of contaminants of emerging concern in natural and engineered systems. His research combines environmental chemistry and engineering approaches to investigate contaminant behavior and identify strategies for improving water quality. Conrad received a bachelor’s degree in environmental engineering from Johns Hopkins University and a doctoral degree in civil and environmental engineering from Stanford University.

Dr. Hannah McIntyre is an engineer at Geosyntec Consultants, Inc. in Kansas City, Missouri. Hannah supports clients in addressing PFAS and other chemicals of emerging concern through site investigations, remedial investigations, litigation support, and compliance with evolving regulations and standards. She applies knowledge gained through research and field experience to evaluate and implement innovative PFAS treatment technologies. Hannah has contributed to the development of guidance documents, presentations, and fact sheets on a lines of evidence approach to assess PFAS remedial technologies for the U.S. Department of War and the United Kingdom Environment Agency. She has supported multiple SERDP and ESTCP projects focused on PFAS treatment and destruction technologies. Hannah received bachelor’s and master’s degrees in civil engineering and a doctoral degree in civil engineering and chemistry from the University of Missouri, Kansas City.