This Corrective Action Decision Document identifies and rationalizes the U.S. Department of Energy, Nevada Operations Office's selection of a recommended corrective action alternative (CAA) appropriate to facilitate the closure of Corrective Action Unit (CAU) 230, Area 22 Sewage Lagoons, and CAU 320, Area 22 Desert Rock Airport Strainer Box, under the Federal Facility Agreement and Consent Order. Referred to as CAU 230/320, both CAUs are located at the Nevada Test Site (NTS) and comprise two Corrective Action Sites (CASs), 22-03-01 (Sewage Lagoons) and 22-99-01 (Strainer Box). The Area 22 Sewage Lagoons site also includes a buried Imhoff Tank, sludge bed, and associated sewer piping. A September 1999 corrective action investigation identified the only contaminant of concern above preliminary action levels at this CAU (i.e., total petroleum hydrocarbons as diesel-range organics). During this same investigation, three Corrective Action Objectives (CAOs) were identified to prevent or mitigate exposure to subsurface debris and contaminated soil. Based on these CAOs, a review of existing data, future use, and current operations in Area 22 of the NTS, three CAAs were developed for consideration: Alternative 1 - No Further Action, Alternative 2 - Closure in Place with Administrative Controls, and Alternative 3 - Excavation and Removal. These alternatives were evaluated based on four general corrective action standards and five remedy selection decision factors. Alternative 3 was chosen on technical merit as the preferred alternative for CAU 230/320. This alternative was judged to meet all applicable state and federal regulations for closure of the site and will eliminate potential future exposure pathways to the buried debris and contaminated soils at both of the CASs within Area 22.
