Distribution and Evolution of Groundwater Contamination at the RCA Taoyuan Plant
Date Issued
2015
Date
2015
Author(s)
Yao, I-Hsin
Abstract
Soil and groundwater at the Radio Corporation of America (RCA) Taoyuan Plant in Taiwan were found contaminated by chlorinated volatile organic compounds (VOCs) in 1987. The pollution may be attributed to improper dumping or leakage of chlorinated solvents. The major pollutants are tetrachloroethylene (PCE), trichloroethylene (TCE), 1, 1, 1- trichloroethane (1, 1, 1-TCA) and their degradation byproducts. These VOCs are dense non-aqueous phase liquids (DNAPLs) which can hardly be dissolved in groundwater. The residual DNAPLs along the migration pathway usually dissolve very slowly in groundwater, and thus become long-term contamination sources. Site characterization indicated that the uppermost aquifer is a thick gravel layer. The deep aquifer is composed of sand interbedded with mud layers. Groundwater flows northward horizontally and downward vertically. Contamination was found primarily in the northwest and north sides of the plant. The pump and treat method had been implemented, but failed to remediate groundwater contamination. Enhanced reductive dechlorination method has been adopted to clean up contaminants since 2005. By injecting reducing agents, the aquifer condition became favorable to anaerobic biodegradation. The concentration of PCE and TCE in the groundwater reduced significantly at most wells seven years later. However, the concentration of vinyl chloride (VC), a highly toxic chemical produced through biodegradation processes, exceeded the regulatory standard at many wells. Besides, the contaminants have migrated off-site for years. Therefore, an effective solution for the cleanup of VC contamination and off-site contamination should be considered in the future.
Subjects
RCA Taoyuan Plant
groundwater
contamination remediation
tetrachloroethylene
trichloroethylene
vinyl chloride
SDGs
Type
thesis
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