This decision document presents the U.S. Army's Selected Remedy for Operable Unit 1 (OU-1), the T-25 Area ground water at the Natick Laboratory Army Research, Development, and Engineering Center National Priorities List Site, at the U.S. Army Soldier Systems Center (SSC) in Natick, Massachusetts (Site). It was developed in accordance with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA) and to the extent practicable, the National Oil and Hazardous Substances Contingency Plan (NCP), 40 CFR Part 300 et seq., as amended; as well as in accordance with the Department of the Army policy. The Assistant Chief of Staff for Installation Management or the Deputy Assistant Secretary of Army for Environmental, Safety and Occupational Health, and the Director of the U.S. Environmental Protection Agency (EPA) New England Region have been delegated the authority to approve this Record of Decision (ROD). This decision is based on the Administrative Record that has been developed in accordance with Section 113(k) of CERCLA. The Administrative Record Index identifies each of the items considered during the selection of the remedial action. The Commonwealth of Massachusetts concurs with the selected remedy.