Description: In 1985, carbon tetrachloride was discovered in the groundwater at Agra, Kansas, during routine sampling of public water supply wells. Two of Agra's four public water supply wells contained low but detectable levels of carbon tetrachloride; the concentrations in wells PWS-3 and PWS-4 exceeded the maximum contaminant level. These wells were removed from service in 1986, although they remain available for uses other than drinking water. Other public wells, outside the area of contamination, supply drinking water for the city of Agra. In 1987-2005, the Kansas Department of Health and Environment (KDHE) and the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) conducted investigations to delineate the contaminant plume and to identify source areas for the contamination - which results from the past use of grain fumigants containing carbon tetrachloride. Source areas were identified on the former CCC/USDA grain storage facility property and on the Producers Agricultural Marketing Association, Inc., property located to the south (Argonne 2006). The contaminant plume extends to the southeast, toward well PWS-3, from the identified source areas. Both the CCC/USDA and Pro-Ag Marketing are currently implementing KDHE-approved interim measures (IMs). To address the contamination identified on its former property, the CCC/USDA is implementing a source control IM consisting of large-diameter boreholes (LDBs) coupled with soil vapor extraction (SVE) and air sparging (AS). Pro-Ag Marketing plans to use groundwater extraction to address the downgradient plume. The CCC/USDA and Pro-Ag completed installation of the two interim measures in May 2009 and August 2009, respectively. The performance and assessments of the effectiveness of the IMs are being reported separately by the responsible entities. As part of the IM process, the KDHE (2008) requested the development of a joint sitewide groundwater monitoring plan to allow periodic assessment of the effectiveness of the separate IMs being implemented by ...
Date: January 14, 2010
Creator: LaFreniere, L. M.
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