Characterizing natural attenuation in groundwater at a chlorinated solvent contaminated industrial site in Virginia

Abstract

Abstract Maas, John R. Master of Environmental Assessment Program. Characterizing Natural Attenuation in Groundwater at a Chlorinated Solvent Contaminated Industrial Site in Virginia This case study focuses on the monitored natural attenuation (MNA) of historical chlorinated solvent releases at an industrial manufacturing facility in Virginia, referred to as the site. The primary constituent of concern for this study is Trichloroethylene (TCE). The United States Environmental Protection Agency has classified TCE as carcinogenic to humans. The areas of impacted groundwater are examined and categorized according to occurrence of the source product TCE, light and dense non-aqueous phase liquids, TCE breakdown or daughter products, and geochemical properties. The United States Environmental Protection Agency’s Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Ground Water (EPA/600/R-98/128, 1998) is used as guidance in this study. This document details the EPA's approach for applying and assessing MNA as a cleanup tool for chlorinated solvents in groundwater. Monitoring of TCE biodegradation can be a suitable, cost-effective course of remedial action for a contaminated site. MNA can work as the sole remedial option or with other more active remedial tools at some sites where biogeochemical conditions favor natural processes that degrade or immobilize harmful contaminants. The high concentrations and occurrence of TCE as a dense non-aqueous phase liquid prohibit the feasibility of MNA as a sole remedial option for the site. However, data collected indicates that areas of the site are amenable to MNA, and that MNA may be able to play a larger role when applied in combination with more aggressive clean up action at source areas. This paper demonstrates that while MNA is an enticing and cost effective remedial alternative, exclusive reliance on natural attenuation for contaminant degradation is not practical for all sites.