Site Characterization and Optimization of Corrective Actions at a Chlorinated-Solvent Spill Site

Abstract

The industrial solvent, trichloroethene (TCE), is among the most ubiquitous chlorinated compounds found in subsurface contamination. Operation of an avionics repair shop at a military base has resulted in past release of solvent chemicals including TCE and other chlorinated aliphatic hydrocarbons. The objectives of this study were to investigate the occurrence of natural remediation process and the feasibility of using natural remediation as the remedial option at this site. The following tasks have been performed: (1) site characterization to delineate the lateral and vertical extent of contaminants in the subsurface; (2) field investigation of natural remediation; and (3) efficiency of TCE removal through natural remediation in the field. Results indicate that TCE biodegradation occurred at this site, and natural remediation is a possible remedial alternative for TCE plume containment. Evidences for the TCE natural remediation included: (1) decreased TCE and other chlorinated compounds concentrations along the transport path; (2) production of the TCE degradation byproducts (including ethane); (3) decreased total organic carbon along the transport path, (4) deceased pH in the spill source area; (5) production of chloride ion and carbon dioxide. Experiences obtained from this study would be helpful in developing a site remedial protocol for other DNAPL sites.