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Initial private drinking water well sampling at Navarre, Kansas in 1990 and 1991 indicated carbon tetrachloride in excess of 500 micrograms per liter (µg/L) and nitrate in excess of 300 milligrams per liter (mg/L) above the regulatory limits of 5 µg/L and 10 mg/L respectively. In 1992 KDHE conducted a Preliminary Assessment (PA) of the Navarre Site. The PA concluded that source areas for the carbon tetrachloride and nitrate contamination appeared to be the former Commodity Credit Corporation/United States Department of Agriculture (CCC/USDA) grain storage facility location and the North Central Kansas Cooperative (NCKC), respectively.

From 1992 to 1995, CCC/USDA funded a site characterization and feasibility study of the Site, both of which focused primarily on the carbon tetrachloride contamination. A carbon tetrachloride soil source was detected in the northern portion of the former CCC/USDA facility. CCC/USDA funded the installation of point-of-entry (POE) filter systems for treatment of carbon tetrachloride for Navarre residents with domestic wells within the contaminant plume. In late 1997, the KDHE State Water Plan program directed an investigation of the Site to locate and sample all wells to identify impact from nitrate and carbon tetrachloride, identify the source area(s) for nitrate and delineate the extent of nitrate contamination, and document all residents using domestic drinking water wells. A number of the private wells which were identified with carbon tetrachloride values above the MCL had disconnected or failed POE filter systems. One soil sample collected near the NCKC fertilizer storage area in 1997 indicated nitrate in excess of 3,500 mg/kg, identifying a nitrate contamination source area.

Following an additional site investigation, Papadopolous and Associates in 2000 reported the NCKC might be a source for some of the carbon tetrachloride contamination and all of the nitrate contamination. In 2001, CCC/USDA funded a connection with the Dickinson County Rural Water District #2 to households in Navarre.

NCKC entered into a Consent Order with KDHE in 2004 (Navarre Co-op Site C5-021-71239), which obligates the facility to perform additional investigation of the nitrate and carbon tetrachloride contamination at the Site.

In 2006 CCC/USDA began an additional investigation that involved soil and groundwater sampling on the USDA and NCKC site and installation of monitoring wells in the area just north of the former CCC/USDA property. Results of this study showed low concentrations of carbon tetrachloride in the soils in the southern part of the CCC/USDA site and that the distribution of groundwater contamination at the Site is predominately limited to the upper part of the aquifer.

In May 2014, CCC/USDA submitted a limited investigation work plan to determine the extent of carbon tetrachloride contamination in groundwater at the Site. KDHE approved the work plan with comments in May 2014, and field activities under the work plan began in August of 2014. The final version of the Limited Investigation Report was approved by KDHE in December 2015. KDHE has requested USDA/CCC consider conducting a groundwater monitoring event to evaluate the current site conditions regarding carbon tetrachloride contamination.