Corrective Action Decision Document for Corrective Action Unit 254: Area 25 R-MAD Decontamination Facility, Nevada Test Site, Nevada

This Corrective Action Decision Document identifies and rationalizes the US 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) 254, R-MAD Decontamination Facility, under the Federal Facility Agreement and Consent Order. Located in Area 25 at the Nevada Test Site in Nevada, CAU 254 is comprised of Corrective Action Site (CAS) 25-23-06, Decontamination Facility. A corrective action investigation for this CAS as conducted in January 2000 as set forth in the related Corrective Action Investigation Plan. Samples were collected from various media throughout the CAS and sent to an off-site laboratory for analysis. The laboratory results indicated the following: radiation dose rates inside the Decontamination Facility, Building 3126, and in the storage yard exceeded the average general dose rate; scanning and static total surface contamination surveys indicated that portions of the locker and shower room floor, decontamination bay floor, loft floor, east and west decon pads, north and south decontamination bay interior walls, exterior west and south walls, and loft walls were above preliminary action levels (PALs). The investigation-derived contaminants of concern (COCs) included: polychlorinated biphenyls, radionuclides (strontium-90, niobium-94, cesium-137, uranium-234 and -235), total volatile and semivolatile organic compounds, total petroleum hydrocarbons, and total Resource Conservation and Recovery Act (Metals). During the investigation, two corrective action objectives (CAOs) were identified to prevent or mitigate human exposure to COCs. Based on these CAOs, a review of existing data, future use, and current operations at the Nevada Test Site, three CAAs were developed for consideration: Alternative 1 - No Further Action; Alternative 2 - Unrestricted Release Decontamination and Verification Survey; and Alternative 3 - Unrestricted Release Decontamination and Verification Survey and Dismantling of Building 3126. These alternatives were evaluated based on four general corrective action standards and five remedy selection decision factors, and the preferred CAA chosen on technical merit was Alternative 2. This CAA was judged to meet all requirements for the technical components evaluated and applicable state and federal regulations for closure of the site, and reduce the potential for future exposure pathways