Remediation of 1,1,1-Trichloroethane via Sequential Thermally Enhanced Hydrolysis and In Situ Chemical Oxidation

摘要

Multiple areas of 1,1,1-trichloroethane (TCA) contamination were encountered during investigations at a former aerospace manufacturing plant. In one area, leaks from a former degreaser pit resulted in TCA concentrations exceeding 1% of its aqueous solubility (13,300 micrograms per liter [μg/L]). Dense nonaqueous-phase liquid (DNAPL) also was present in the source zone. The objective of the remedial effort was to reduce contaminant concentrations in the source zone to below the 1% TCA solubility value. After extensive laboratory treatability testing, the selected remedy for the site included heating of the saturated zone in the source area to enhance TCA removal via hydrolysis, followed by the injection of sodium persulfate to oxidize remaining dissolved-phase TCA and hydrolysis byproducts. Remedial investigations were conducted to develop the remedial design basis for the project necessary to achieve the site's remedial objectives. A greater understanding of the hydrolysis reaction rates and byproduct formation; oxidation rates at varying temperatures; and remedial time frame estimates also were explored.