“SERDP & ESTCP Strategic Research for Managing Chlorinated Solvents in Groundwater"  by Dr. Andrea Leeson

The Department of Defense (DoD) is responsible for remediating and protecting groundwater aquifers associated with military installations. Contaminated groundwater is the largest liability in the Defense Environmental Restoration Program. At many sites, groundwater resources have been contaminated with chlorinated ethenes and ethanes due to past usage and disposal practices. SERDP and ESTCP have funded numerous research and technology demonstrations to address chlorinated solvent sites since the early 1990s. Less complex sites have been cleaned up to some extent but may still require monitoring and management, and the remaining sites are more challenging. In July 2018, SERDP and ESTCP hosted a two-day chlorinated solvents expert workshop to review the current state of science, evaluate the adequacy of existing tools and technologies, and identify and prioritize research priorities to assist SERDP and ESTCP in developing a strategic plan for funding future research and demonstration projects related to chlorinated solvents. The discussion focused on identifying major challenges and opportunities in site management, promising technologies and advances, and key research and development needs over the next five years to improve site management. One pressing challenge is a framework for prioritizing the need for remedial actions among the large numbers of chloroethene contaminated sites. This presentation will focus on workshop outcomes that will guide future SERDP and ESTCP investments as well as findings from recent relevant projects. Example topics include remedy optimization, fine scale delineation, post remediation performance, long-term attenuation, mixed contamination, and abiotic attenuation.

“Effective Treatment of Chlorinated Solvents in Clay and Silt Using Electrokinetic Techniques”  by Mr. Evan Cox

Contaminants in clays and silts are long-term sources of pollutants to groundwater, requiring costly remediation and monitoring over many decades. Significant advances have been made in the past few years in the area of electrokinetically (EK) enhanced amendment delivery to treat contaminant source areas in low permeability and highly heterogeneous subsurface materials.  EK is an innovative approach that uses electrokinetic mechanisms to promote the migration of amendments through clays/silts through electromigration, electroosmosis and/or electrophoresis.  EK approaches are not dependent on hydraulic conductivity and can therefore achieve uniform and rapid distribution of amendments in clays and silts.  Amendments can include electron donors (e.g., lactate), electron acceptors (e.g., nitrate), and/or microorganisms (e.g., Dehalococcoides, Dehalobacter) for in situ bioremediation (EK-BIO), or oxidants such as permanganate or thermally-activated persulfate for in situ chemical oxidation (EK-ISCO and EK-TAP, respectively). This presentation will discuss how and where these EK remediation technologies work in addition to providing in-depth results from a recently completed successful ESTCP demonstration/validation project of the EK-BIO technology to treat a tetrachloroethene (PCE) source area in clay at Naval Air Station Jacksonville, Florida (NAS-JAX; ESTCP ER-201325).

Dr. Andrea Leeson is the Deputy Director of SERDP and ESTCP as well as the Program Manager for SERDP and ESTCP’s Environmental Restoration program area. Dr. Leeson has been with SERDP and ESTCP since 2001. Prior to that, she was a Research Leader at Battelle Memorial Institute where she conducted scientific research on in situ bioremediation and the design and implementation of innovative biological, chemical and physical treatment technologies for site remediation and industrial wastewater. She received her doctoral degree in Environmental Engineering from The John Hopkins University.

Mr. Evan Cox is a senior principal remediation scientist at Geosyntec Consultants with more than 25 years of demonstrated experience in the development and application of innovative in situ remediation technologies for chlorinated and energetic chemicals in subsurface environments.  Mr. Cox has been the Principal Investigator for 4 SERDP and 5 ESTCP projects since 2000.  Two of these projects won SERDP’s Cleanup Project-of-the-Year Award for Environmental Restoration (ER-1164 in 2001 and ER-1557 in 2010).  Mr. Cox has been actively involved in development, demonstration and validation of novel in situ electrokinetic techniques to treat chlorinated solvent source areas in low permeability and heterogeneous materials.  These techniques, referred to as Electrokinetic Bioremediation (EK-BIO) and Electrokinetically-delivered, Thermally-Activated Persulfate (EK-TAP) are the subjects of two of Mr. Cox’s ESTCP projects (ER-201325 and ER-201626 respectively).