The Site is situated in Bexar County, in the City of Leon Valley, in the northwest section of the City of San Antonio, Texas. The current plume size is estimated to be approximately one mile long by one-half mile wide. The plume is centered in a business area, and extends to a residential area. The Site is bounded by Poss Road and Grissom Road, southwest of Bandera Road. Ongoing sampling and investigation may alter the estimated plume extent.
The Site currently includes six private drinking water wells that draw water from the Edwards aquifer. The wells are approximately 350 to 400 feet deep. The maximum observed concentration in the wells is 111.6 ppb of PCE and 5.76 ppb of TCE. The MCL for both is 5 ppb. PCE and TCE cannot be detected by taste or smell in water until it reaches concentrations well above the MCL. There are two City of Leon Valley public water supply wells within one mile of the center of the plume.
Releases or threatened release into the environment of a hazardous substance, pollutant or contaminant PCE has been detected above the MCL in six wells within the Site boundaries. PCE is a hazardous substance listed in Section 101(14) of CERCLA, 42 U.S.C. '9601(14) and 40 CFR '302.4. The Texas Department of Health and Human Services (DHHS) has determined that PCE may reasonably be anticipated to be a carcinogen.
The Site was added to the National Priorities List (NPL) on March 7, 2007.
The 2004 investigation by TCEQ led to the identification of the contaminated wells. Approximately thirty-three wells have been routinely sampled since that time. The United States Geological Survey (USCG) was recently tasked by EPA to conduct a well survey to identify all wells in the area that could possibly be affected by the plume. Additional wells located by that survey are being screened and prioritized for initial sampling. The EPA has also conducted searches for potential sources of the contamination. The specific source(s) has not been identified.
Additional investigations are continuing to attempt to identify the source(s) and to define the extent of the plume. Requests for access to conduct sampling of the wells are being sent to property owners identified in the USGS well survey.
The removal action involves the installation of a water line and connection to public water systems. Currently, seven properties will be connected to an existing water supply line from a Municipal Utility District (MUD) or other water supply authority. Other properties may be identified with contaminated wells as the investigation continues. The property owners will be responsible for paying for their water use. If the existing water wells are to remain in service, they will be isolated from the public system. Trenches and any disturbance of sidewalks, driveways, or other structures will be restored.
There are no key issues associated with this site.
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