CORRECTIVE ACTION DECISION DOCUMENT FOR CORRECTIVE ACTION UNIT 423: BUILDING 03-60 UNDERGROUND DISCHARGE POINT, TONOPAH TEST RANGE, NEVADA, REVISION 0, JUNE 1998

This Corrective Action Decision Document has been prepared for the Area 3 Building 03-60 Underground Discharge Point (Corrective Action Unit 423) in accordance with the Federal Facility Agreement and Consent Order of 1996 (FFACO, 1996). Corrective Action Unit 423 is located at the Tonopah Test Range and is comprised of Corrective Action Site 03-02-002-0308. The purpose of this Corrective Action Decision Document is to identify and provide a rationale for the selection of a recommended corrective action alternative for Corrective Action Unit 423. The scope of this Correction Action Decision Document consists of the following: � Develop corrective action objectives. � Identify corrective action alternative screening criteria. � Develop corrective action alternatives. � Perform detailed and comparative evaluations of the corrective action alternatives in relation to the corrective action objectives and screening criteria. � Recommend and justify a preferred corrective action alternative for the Corrective Action Unit. In January 1998, a corrective action investigation was performed as set forth in the Corrective Action Investigation Plan for Corrective Action Unit No. 423: Building 03-60 Underground Discharge Point, Tonopah Test Range, Nevada (DOE/NV, 1997). A hydrocarbon plume was found to emanate from near the bottom of the Underground Discharge Point to the west. The plume encompasses approximately 65 square meters (700 square feet). The highest total petroleum hydrocarbon level detected was 2,400 milligrams per kilogram. No other contaminants were detected above preliminary action levels. Details of the investigation can be found in Appendix A of this document. Based on the potential exposure pathways identified during the Data Quality Objectives process, the following corrective action objectives have been identified for Corrective Action Unit 423: � Prevent or mitigate human exposure to subsurface soil containing contaminants of concern. � Prevent adverse impacts to groundwater quality. Based on the review of existing data, future land use assumption, and current operations at the Tonopah Test Range, the following alternatives were developed for consideration at the Building 03-60 Underground Discharge Point: � Alternative 1 - No Action � Alternative 2 - Closure in Place with Administrative Controls � Alternative 3 - Partial Excavation, Disposal, and Administrative Controls � Alternative 4 - In Situ Bioremediation The corrective action alternatives were evaluated based on four general corrective action standards and five remedy selection decision factors. Based on the results of this evaluation, the preferred alternative for Corrective Action Unit 423 is Alternative 2, Closure in Place with Administrative Controls. The preferred corrective action alternative was evaluated on technical merit, focusing on performance, reliability, feasibility, and safety. The alternative was judged to meet all requirements for the technical components evaluated. The alternative also meets all applicable state and federal regulations for closure of the site and will reduce potential future exposure pathways to the contaminated soils