Field Investigation at a Chlorinated Ethylene Contaminated Site

Abstract

Tetrachloroethylene (PCE) and trichloroethylene (TCE) are among the most ubiquitous chlorinated contaminants or compounds found in the subsurface environment. A recent site groundwater investigation focused on the underground storage tanks, that found elevated aqueous PCE, TCE, and their degradation byproducts. These chlorinated ethylenes are not commonly found at gas vender stations in Taiwan. The purpose of this monitoring work is to investigate and verify contamination sources in the vicinity of the gas vender station. Measurements of dissolved oxygen content, redox potential, and various cations as well as anions were conducted on the site. The results indicate that the underground environment remains in reducing conditions, but not strictly in anaerobic conditions. Since the sulfate concentration remains at around the background level and the dissolved iron stays below the detection limit, the sulfate and iron reduction are not prominent. Based on the cone penetration geological testing results, a less permeable silt and clay interbed locates at