The Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), operated a grain storage facility in Hilton, Kansas, in 1954-1965. In 1992, carbon tetrachloride was first identified, at a concentration of 910 {micro}g/L, in groundwater from well GW01 at Hilton. This discovery occurred in association with the sale of the private grain storage facility on which well GW01 is located to the current owner, the Mid-Kansas Cooperative Association. The Kansas Department of Health and Environment conducted investigations at Hilton in 1992-1994. In 1996-1997, Argonne National Laboratory conducted Phase I and Phase II investigations on behalf of the CCC/USDA to characterize the distribution of the carbon tetrachloride contamination identified in well GW01, the stratigraphic units potentially hosting contaminant migration, and local hydrogeology in the Hilton area. The 2007 targeted investigation reported here focused specifically on the former CCC/USDA property at Hilton, west of the railroad tracks. (Until a property record search in 2005, the location of the CCC/USDA's former facility at Hilton was not known with certainty.) The objectives of the investigation, as implemented, were to (1) investigate for carbon tetrachloride contamination in the shallower soil and shallow aquifer units below the former CCC/USDA property and (2) …