Publication Summary

Tetrachloroethylene (PCE) contamination of shallow groundwater was discovered in 1997 during an environmental site assessment of property in Shelton, Washington. PCE was detected at a concentration of 130 µg/L in groundwater from a temporary shallow boring. The likely source of the contamination was identified as the dry cleaning facility located adjacent to where the site assessment was being conducted. Ground water samples will be collected quarterly over a one-year period to determine if PCE and its breakdown products (trichloroethylene, dichloroethylene, and vinyl chloride) are present at deeper depths of the aquifer, and if concentrations are below the MTCA clean-up levels.

Tetrachloroethylene (PCE) contamination of shallow groundwater was discovered in 1997 during an environmental site assessment of a property in Shelton, Washington. PCE was detected at a concentration of 130 µg/L in groundwater from a temporary shallow boring. The most likely source of the contamination was identified as the dry cleaning facility located adjacent to the property where the site assessment was being conducted. In 1993, a new dry cleaning machine was installed. As the old cleaning machine was being removed, an unknown quantity of dry cleaning solvent, assumed to be PCE, was reportedly spilled and infiltrated through the broken asphalt in the alley behind the building. The spill event is assumed to be the source of groundwater contamination. In July 1998, four shallow (15 feet deep) monitoring wells were installed to sample the groundwater. PCE contamination has primarily been detected in the well located where the spill was reported, with concentrations ranging from 280 ug/L (July 1998) to 25 ug/L (September 2000). Groundwater data indicate that contaminant concentrations are decreasing. For this project, four additional wells have been installed to gain a better understanding of contaminant concentrations at deeper depths. Three of the wells were installed adjacent to the dry cleaners to a depth of 45 feet. The fourth well, which is assumed to be downgradient of the site, was installed to a depth of 60 feet. Ground water samples will be collected from the eight monitoring wells quarterly over a one-year period to determine if PCE and its breakdown products (trichloroethylene, dichloroethylene, and vinyl chloride) are present at deeper depths of the aquifer, and if concentrations are below the Model Toxic Control Act clean-up levels. This information will assist in determining if the site should be considered for no further action or will require additional investigation or possible remedial action.

Link to EIM data for User Study ID PMAR0001