Boston, Mass. -- EPA has approved an amendment to the comprehensive cleanup plan to address contamination at the Kearsarge Metallurgical Corporation Superfund Site in Conway, N.H.
The 2012 Record of Decision Amendment will provide a comprehensive approach for the site that addresses all current and potential future risks. The remaining remedial measures will prevent the migration of contaminants from the Site in groundwater and restore groundwater to concentrations at or below the drinking water standards through natural processes.
EPA’s amended plan includes the following major components:
- The remaining groundwater contamination will be destroyed by Monitored Natural Attenuation. A groundwater pump-and-treat system operated for more than 10 years removing more than 99 percent of the contaminants in the subsurface. Modeling demonstrated that the remaining contaminants, less than 3 pounds in the groundwater, will be reduced to drinking water standards by natural processes within 18 years. Groundwater monitoring will ensure that the contaminants do not migrate. If necessary, a contingent remedy will be performed to halt any contaminant migration that does occur;
- The cleanup level for 1,1-Dichloroethane was changed from 3,650 parts per billion (established in the Explanation of Significant Differences issued in Sept. 2003), to 81 parts per billion based on recently established Standards by the State of New Hampshire;
- A cleanup level for 1,4-Dioxane of 3 parts per billion is established based on the recently established Standards by the State of New Hampshire;
- Institutional controls, primarily in the form of Activity and Use Restrictions (AUR) were modified. The existing AUR will be changed to allow non-industrial and non-commercial structures on the property provided that adequate engineering controls are installed on those structures to prevent any real or potential unacceptable exposure to vapors originating from the groundwater contaminants. The existing AUR prevents the use of groundwater at the Site.
Five-year reviews will occur to ensure that the remedy continues to be protective of human health and the environment.
More information: Background documents and history of EPA’s work to cleanup contamination at the site are available at: (www.epa.gov/ne/superfund/sites/kearsarge) .
The entire Administrative Record is also available for review at the Conway Public Library, 15 E. Main Street in Conway, N.H.