The Department of Defense (DoD) must maintain a continuous effort to characterize, treat, monitor and manage any contaminated groundwater sites under its purview. While many sites have been cleaned up, more complex locations remain. In situ particulate/colloidal amendments are designed to adsorb contaminants in groundwater, which reduce their dissolved phase concentration. Before these amendments can be applied as a common approach at sites, more research is needed to understand the processes influencing the effectiveness and fate of particulate amendments for in situ treatment of chemicals of concern (COCs) in groundwater.

The following new SERDP projects aim to improve site management, specifically for groundwater sites impacted by chlorinated volatile organic compounds (CVOCs) and per- and polyfluoroalkyl substances (PFAS), by improving tools and guidance for applying commercially available amendments at DoD sites.

• Dr. Albert Juhasz at the University of South Australia and his team will use a combination of methods to examine claims regarding sorption/biodegradation of COCs on particulate amendments for in situ treatment of groundwater. This limited scope project will address COC bioavailability, biodegradability, and sorption concepts using model polycyclic aromatic hydrocarbons (phenanthrene) and PFAS. Research outcomes will provide a methodology for continual monitoring of model aquifers providing high sample density and permitting a robust and rapid analytical approach for particulate amendment assessment. (Project Overview)

• At Virginia Tech, Dr. Cheng Chen and his team will improve the understanding of particulate amendment transport, compaction, and remedial efficacy in artificially created hydraulic fractures of low-permeability clay formations contaminated by CVOCs. They will use laboratory experiments and scalable numerical modeling tools to help DoD site managers and remediation practitioners better predict granular activated carbon (GAC) amendment transport and distribution in fractures across multiple spatial scales. Such insights will be extremely valuable in optimizing designs of field injection strategies for in situ environmental remediation at DoD sites. (Project Overview)

• Dr. Neil Thomson at the University of Waterloo and his team will investigate the factors that affect the adsorption and desorption of PFAS on activated carbon (AC) in the presence of co-occurring chemicals, the transport and attachment of colloidal activated carbon (CAC) in porous media, and the long-term adsorption capacity and potential for PFAS re-release. The project team will evaluate the in situ immobilization of groundwater plumes containing PFAS by AC barriers that are created by injecting powdered activated carbon (PAC) or CAC into the subsurface. (Project Overview)

• At the University of Texas at Austin, Dr. Charles Werth and his team will determine the efficacy of particulate carbon amendment (PCA) in arresting down-gradient plume migration, and the operating parameters that maximize PCA performance. Project results will provide insight regarding injection of PCA in heterogeneous CVOC and PFAS groundwater aquifers and the technology’s ability to mitigate down-gradient plume migration. (Project Overview)

• Dr. Dimin Fan from Geosyntec Consultants and his team will study the mechanisms and processes involved in AC-based treatment technology, characterizing and quantifying the dynamic interactions between adsorption and biodegradation. With a better understanding of these core processes, project results will help predict the long-term performance of this technology in applications at DoD sites. (Project Overview)

• At the Oregon Health & Science University, Dr. Paul Tratnyek and his team will develop and validate a novel method for evaluating synergistic sorption/degradation effects in AC-amendments. This limited scope project will use laboratory experiments and numerical modeling to build a new electroanalytical tool for characterizing AC-amended systems and provide an improved quantitative conceptual understanding of AC-based sorption and degradation. (Project Overview)

• Dr. Amanda Barker from the U.S. Army Engineer Research and Development Center’s Cold Regions Research and Engineering Laboratory will analyze the effectiveness of two mineral-based soil amendments to immobilize PFAS in groundwater systems. This limited scope project will conduct laboratory-based column flow through experiments and batch adsorption reactors to provide a better understanding of PFAS sorption and immobilization using these amendments. (Project Overview)

• At George Washington University, Dr. Xitong Liu and his team will evaluate the long-term performance of CAC for in situ treatment of PFAS-impacted coastal groundwater. The team will establish models for predicting CAC barrier to help DoD site managers select the appropriate CAC products for PFAS treatment. (Project Overview)