| 1,1,1-Trichloroethane (1,1,1-TCA) is one of the most commonly identified pollutants in contaminated soil and groundwater at hazardous waste sites. Hydraulic injection of granular zero valent iron (ZVI) stabilized with guar gum was performed at an active field site contaminated with chlorinated volatile organic compounds (cVOCs) including 1,1,1-TCA, 1,1-dichloroethane (1,1-DCA) and chloroethane (CA). Approximately 17,000 kg and 20,000 kg ZVI was injected and backfilled into the source zone. cVOC concentrations were monitored at the site before and after injection. Microcosm batch studies prepared using site groundwater indicated biodegradation occurs in the presence of ZVI and indigenous microbial communities were capable of biodegrading 1,1,1-TCA to CA. Reducing conditions were present nine months after injection. Concentrations were reduced from 37 to 94 percent. Quantification of groundwater samples for microbiological analyses demonstrated abiotic and biodegradation occurred following injection. This study demonstrates potential for application of guar gum-stabilized ZVI injection in the removal of 1,1,1-TCA. |
