In September 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) initiated periodic sampling of groundwater in the vicinity of a grain storage facility formerly operated by the CCC/USDA at Morrill, Kansas. On the basis of available information, the CCC/USDA believes that one or more third parties operated this facility after termination of the CCC/USDA's lease in 1971. The sampling at Morrill is being performed on behalf of the CCC/USDA by Argonne National Laboratory, in accord with a monitoring program approved by the Kansas Department of Health and Environment (KDHE), to monitor levels of carbon tetrachloride contamination identified in the groundwater at this site (Argonne 2004, 2005a). Under the KDHE-approved monitoring plan (Argonne 2005b), the groundwater has been sampled twice yearly for a recommended period of two years. The samples are analyzed for volatile organic compounds (VOCs), as well as for selected geochemical parameters to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. The sampling is presently conducted in a network of 12 monitoring wells and 3 private wells (Figure 1.1), at locations approved by the KDHE. The scope of the originally approved monitoring has been expanded to include …