Twelve dry cleaning sites were evaluated in the Houston area. At the dry cleaning sites studied, the contamination may be attributed to deficiencies in the separation equipment of the dry cleaning equipment, allowing free phase PCE to enter the sanitary sewer lines and escape by permeating through the pipe, or through defects in the pipe. Three sites with different geologic characteristics were chosen for intensive study to examine if there exists a pattern of transformation of PCE to TCE in the sites. Transformation is compared by calculating the ratio of PCE to TCE for each well for a single sampling event, and by modeling at one of the sites.
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