Corrective Action Decision Document/Closure Report for Corrective Action 405: Area 3 Septic Systems, Tonopah Test Range, Nevada Rev. No.: 0, April 2002

This Corrective Action Decision Document/Closure Report (CADD/CR) has been prepared for Corrective Action Unit (CAU) 405, Area 3 Septic Systems, in accordance with the Federal Facility Agreement and Consent Order. Located on the Tonopah Test Range (TTR) approximately 235 miles north of Las Vegas, Nevada, CAU 405 consists of three Corrective Action Sites (CASs): 03-05-002-SW03, Septic Waste System (aka: Septic Waste System [SWS] 3); 03-05-002-SW04, Septic Waste System (aka: SWS 4); 03-05-002-SW07, Septic Waste System (aka: SWS 7). The CADD and CR have been combined into one report because no further action is recommended for this CAU, and this report provides specific information necessary to support this recommendation. The CAU consists of three leachfields and associated collection systems that were installed in or near Area 3 for wastewater disposal. These systems were used until a consolidated sewer system was installed in 1990. Historically, operations within various buildin gs in and near Area 3 of the TTR generated sanitary and industrial wastewaters. There is a potential that contaminants of concern (COCs) were present in the wastewaters and were disposed of in septic tanks and leachfields. The justification for closure of this CAU without further action is based on process knowledge and the results of the investigative activities. Closure activities were performed at these CASs between January 14 and February 2, 2002, and included the removal and proper disposal of media containing regulated constituents and proper closure of septic tanks. No further action is appropriate because all necessary activities have been completed. No use restrictions are required to be imposed for these sites since the investigation showed no evidence of COCs identified in the soil for CAU 405