The Nuclear Metals, Inc. (NMI) Site, also known as the Starmet Corporation Site, is located on a 46.4-acre parcel located at 2229 Main Street in Concord, Middlesex County, Massachusetts. The property is bordered to the north by Main Street, commercial and residential properties, and the Assabet River; to the east by woodland and residential properties; to the west by woodland and commercial/industrial properties; and to the south by woodland and residential properties. The topography of the property slopes down to the north.

From 1958 to the present, the Site has been used by various operators at various times as a specialized research and metal manufacturing facility, which was licensed to possess and process low-level radioactive substances. At various times, site operators used depleted uranium, beryllium, titanium, zirconium, copper, acids, solvents, and other substances at the Site. From 1958 to 1985, site operators disposed of manufacturing by-products, including waste solutions containing depleted uranium mixed with copper, spent acid, and lime, into an unlined holding basin located on-site. Other areas of the Site, including but not limited to a bog, a cooling water recharge pond, septic leaching fields, a sweepings pile, and a small landfill, are also believed to have been used for the disposal of manufacturing wastes.

From approximately the late 1980s to 2000, the current site owner/operator, Starmet Corporation (Starmet), performed certain site investigations and a partial cleanup of the Site under the oversight of the Massachusetts Department of Environmental Protection (MADEP). In 1997, Starmet, with the financial support of the United States Army, excavated approximately 8,000 cubic yards of contaminated soils from the on-site holding basin and disposed of these soils at an off-site disposal facility licensed to accept low-level radioactive wastes.

During previous investigations starting in the 1980s through the present, by others, soils and groundwater beneath the Site were found to contain elevated levels of depleted uranium and elevated levels of beryllium. Past sampling of sediments at the Site has revealed elevated levels of depleted uranium, copper, and volatile organic compounds.

Pursuant to Section 105(8)(b) of CERCLA, 42 U.S.C. 9605(8)(b), the Site was proposed for inclusion on the National Priorities List (NPL) published by the Administrator of EPA in the Federal Register on July 27, 2000 (65 Fed. Reg. 46131, 46137). The Site was listed on the NPL on June 14, 2001 (66 Fed. Reg. 32235, 32241).