In October, 2007, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) presented the document Interim Measure Conceptual Design (Argonne 2007a) to the Kansas Department of Health and Environment, Bureau of Environmental Remediation (KDHE/BER), for a proposed non-emergency Interim Measure (IM) at the site of the former CCC/USDA grain storage facility in Centralia, Kansas (Figure 1.1). The IM was recommended to mitigate existing levels of carbon tetrachloride contamination identified in the vadose zone soils beneath the former facility and in the groundwater beneath and in the vicinity of the former facility, as well as to moderate or decrease the potential future concentrations of carbon tetrachloride in the groundwater. The Interim Measure Conceptual Design (Argonne 2007a) was developed in accordance with the KDHE/BER Policy No.BERRS-029, Policy and Scope of Work: Interim Measures (KDHE 1996). The hydrogeologic, geochemical, and contaminant distribution characteristics of the Centralia site, as identified by the CCC/USDA, factored into the development of the nonemergency IM proposal. These characteristics were summarized in the Interim Measure Conceptual Design (Argonne 2007a) and were discussed in detail in previous Argonne reports (Argonne 2002a, 2003, 2004, 2005a,b,c, 2006a,b, 2007b). The identified remedial goals of the proposed IM were as follows: (1) …

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 …