The FSA through the EERB has been engaged in an ongoing program to address groundwater contamination at grain storage facilities that were formerly operated by the CCC. The CCC grain storage program was in operation between 1933 and 1972. CCC no longer owns any storage capacity.
During the conduct of CCC grain storage operations, fumigation and rodent control were routinely conducted using chemical compounds containing carbon tetrachloride (CT). In 1985, the U.S. Environmental Protection Agency determined CT to be a probable human carcinogen. At some former CCC grain storage locations, residual effects of fumigation have led to groundwater contamination due to unacceptable levels of CT. Since the first discovery of contaminated groundwater in 1988, CCC has been engaged in an active program to identify affected sites and respond with appropriate action to safeguard public health and protect the environment.
At sites where contamination has been identified in a drinking water source at levels above the MCL and a CCC presence has been confirmed, immediate action is initiated to ensure that any human exposure routes are eliminated. These immediate actions are normally limited to bottled water provisions and installation of household filtration systems. Additional and more permanent actions include connections to rural water systems, construction of a new private well in a non-contaminated water zone or installing water treatment systems on existing wells.
In coordination and cooperation with respective states or the U.S. Environmental Protection Agency (EPA), CCC conducts varying levels of site investigations. Any CCC recommendation or decision to proceed with remedial activity at a site is based on the results of a dynamic risk assessment conducted as part of the site characterization process. The objective of this risk assessment process is to evaluate potential human health risks associated with exposure to CT originating from the former CCC grain storage facility. Risk assessments are conducted in accordance with EPA guidelines described in Risk Assessment Guidance for Superfund
, EPA/540/1-89/002. The results of this assessment will show not only where exposure to contaminant may occur within the immediate vicinity of the site, but also whether there is any possibility that other exposures might occur as the contaminant moves off-site with the flow of the groundwater.
Cleanup activities have been conducted at sites where risk assessment results have indicated that the carbon tetrachloride contaminant presents an unacceptable human health threat. Remedial action has also been taken at sites where either state regulators or the U.S. EPA mandate a remedial action.
When conducting remedial activities, CCC is a strong advocate of innovative technologies and beneficial reuse of treated water whenever possible. Although CCC has pump-and-treat systems, this approach is no longer considered to be preferable unless absolutely necessary.