National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List: Partial Deletion of the Rocky Mountain Arsenal Federal Facility

The Environmental Protection Agency (EPA) Region 8 announces the deletion of portions of the On-Post Operable Unit (OU3), specifically the Central and Eastern Surface Areas including surface media and structures (CES), and the surface media of the Off-Post Operable Unit (OU4) (OPS) of the Rocky Mountain Arsenal Federal Facility (RMA) located in Commerce City, Colorado from the National Priorities List (NPL). The NPL, promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, is an appendix of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This partial deletion pertains to the surface media (soil, surface water, sediment) and structures (both former structures that have been demolished and structures retained for future use) within the CES and the surface media of the entire OPS. The rest of the On-Post OU, including groundwater below RMA that is west of E Street, and the groundwater that comprises the Off-Post OU will remain on the NPL and is not being considered for deletion as part of this action. Response activities will continue at those OUs. The EPA and the State of Colorado, through the Colorado Department of Public Health and Environment (CDPHE), have determined that all appropriate response actions under CERCLA, other than operation, maintenance, and five-year reviews, have been completed. However, the deletion of these parcels does not preclude future actions under Superfund.