The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) formerly operated a grain storage facility at Milford, Nebraska. In May 2008, the CCC/USDA directed the Environmental Science Division of Argonne National Laboratory, as its technical consultant, to develop a work plan for a targeted investigation at the Milford site. The purpose of the targeted investigation is to assess the current extent and configuration of the carbon tetrachloride plume downgradient from the former CCC/USDA facility and proximal to the banks of the Big Blue River, which borders the area of concern to the east, southeast, and northeast. In 1995, carbon tetrachloride contamination was detected by the Nebraska Department of Health and Human Services in a private drinking water well and a livestock well 1.25 mi south of Milford (Figure 1.1). The Trojan drinking water well is located directly downgradient (approximately 300 ft east) of the former CCC/USDA facility. Low levels of carbon tetrachloride contamination were also found in the Troyer livestock well, approximately 1,200 ft north of the former CCC/USDA facility.

On March 9, 2001, representatives of the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) and Argonne National Laboratory met with representatives from a number of federal and Nebraska state agencies (the wetlands agencies; see Table 1.1) to discuss the CCC/USDA's proposed aquifer remediation and wetlands restoration project at Utica, Nebraska. As part of those discussions, Argonne outlined preliminary recommendations for a long-term monitoring program to verify and document (1) the performance of the spray irrigation treatment process for the removal of carbon tetrachloride from extracted groundwater, (2) the geochemical quality of the extracted and treated groundwater delivered to the wetlands, and (3) the hydrogeologic and inorganic geochemical impacts of the groundwater delivery. General activities recommended included the following: (1) Periodic sampling and analysis for volatile organic compounds (VOCs) in groundwater extracted at each pumping well and in water discharged from the spray irrigation treatment units. (2) Periodic sampling of groundwater from each pumping well and directly from the sprinkler discharge, for analysis for selected inorganic water quality parameters. The CCC/USDA and Argonne also requested at the March 2001 meeting that the wetlands agencies accept responsibility for developing the ecological and biological monitoring programs needed to meet environmental …