Corrective Action Decision Document for Corrective Action Unit 322: Areas 1 and 3 Release Sites and Injection Wells Nevada Test Site, Nevada, Revision 0 with ROTC 1

Abstract

This Corrective Action Decision Document has been prepared for Corrective Action Unit (CAU) 322, Areas 1 and 3 Release Sites and Injection Wells, Nevada Test Site, Nevada, in accordance with the ''Federal Facility Agreement and Consent Order'' (1996). Corrective Action Unit 322 is comprised of the following corrective action sites (CASs): (1) 01-25-01 - AST Release Site; (2) 03-25-03 - Mud Plant and AST Diesel Release; and (3) 03-20-05 - Injection Wells and BOP Shop. The purpose of this Corrective Action Decision Document is to identify and provide the rationale for the recommendation of a corrective action alternative for each CAS within CAU 322. Corrective action investigation activities were performed from April 2004 through September 2004, as set forth in the Corrective Action Investigation Plan. The purposes of the activities as defined during the data quality objectives process were: (1) Determine if contaminants of concern (COCs) are present; (2) If COCs are present, determine their nature and extent; and (3) Provide sufficient information and data to recommend appropriate corrective actions for the CASs. Analytes detected during the corrective action investigation were evaluated against appropriate preliminary action levels to identify contaminants of concern for each corrective action site. Radiological field measurements were compared to unrestricted release criteria. Assessment of the data generated from investigation activities revealed the following: (1) CAS 01-25-01 contains an AST berm contaminated with total petroleum hydrocarbons (TPH) diesel-range organics (DRO). (2) CAS 03-25-03 includes two distinct areas: Area A where no contamination remains from a potential spill associated with an AST, and Area B where TPH-DRO contamination associated with various activities at the mud plant was identified. The Area B contamination was found at various locations and depths. (3) CAS 03-25-03 Area B contains TPH-DRO contamination at various locations and depths in the area associated with the Mud Plant. (4) CAS 03-20-05 contains TPH-DRO, metals, and radiological contamination within the injection well casing soil and TPH-DRO contamination at the depth coincidental with the bottom of the injection well sump. Based on the evaluation of analytical data from the corrective action investigation, review of future and current operations in Areas 1 and 3 of the Nevada Test Site, and the detailed and comparative analysis of the potential corrective action alternatives, the following corrective actions are recommended for the Corrective Action Unit 322 CASs. Closure in Place with Administrative Controls is the preferred corrective action for the following CASs: (1) CAS 01-25-01, removal of TPH-DRO contamination would pose a significant safety hazard due to the site location. (2) CAS 03-25-03 No contamination remains at Area A (AST Berm); and thus, no further action is the preferred alternative at this part of the CAS. However at Area B, TPH-DRO contamination is varied in concentration and location and the footprint of the CAS is large, removal of contaminated ''pockets'' would be laborious and cost prohibitive. The plutonium-239 surface contamination identified at CAS 03-25-03 Area B has been removed and drummed as a best management practice. (3) CAS 03-20-05, TPH-DRO, metals, and radiological contamination are present in the injection well casing soils. Recommend corrective action includes removal of the liquid in the injection well sump (approximately 3 feet (ft) of liquid at 60 ft below ground surface), grouting the sump, and the area within the injection well casing. The plutonium-239 surface contamination identified at CAS 03-20-05 has been removed and drummed as a best management practice and will be disposed of as low-level radioactive waste. It is recommended that the liquids be removed from the holding tank wells and the sumps of the two outer holding tanks within the BOP Shop, and the sumps be grouted, and the holding tanks filled in to the BOP Shop floor surface. The preferred corrective action alternatives were evaluated on technical merit focusing on performance, reliability, feasibility, and safety. The alternatives were judged to meet all requirements for the technical components evaluated. The alternatives meet all applicable state and federal regulations for closure of the site and will reduce potential future exposure pathways to the contaminated media at Corrective Action Unit 322.