A Pilot Scale EZVI and ZVI Treatment of Unsaturated and Saturated Soil for TCE Reduction
ABSTRACT: Enhanced biological reductive dechlorination, micro-scale zero valent iron (ZVI), and emulsified zero valent iron (EZVI) injections were implemented to treat chlorinated volatile organic compounds (CVOCs) at a former manufacturing facility in western South Carolina. These remedial approaches – until recently typically implemented as standalone technologies –were combined to achieve synergistic reductions of tetrachloroethene (PCE), trichloroethene (TCE), and their reaction products. A total of 38 injections were made over the course of two days in both the unsaturated and saturated zones. The groundwater results from three shallow monitoring wells inside the injection area showed at least 50% reduction in dissolved concentration of PCE and TCE within a year of injection. There was a coincident increase in the appearance of daughter products such as cis-1,2-dichloroethene (cis-1,2-DCE), indicating that reductive dechlorination was occurring. Monitoring also shows reducing conditions persist in the injection area. Analytical results from unsaturated soil sampled after the injections showed all CVOC contaminants to be below USEPA industrial soil standards.