Corrective Action Investigation Plan for Corrective Action Unit 261: Test Cell A Leachfield System, Nevada Test Site, Nevada UPDATED WITH TECHNICAL CHANGE No.1

This Corrective Action Investigation Plan (CAIP) has been developed in accordance with the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the US Department of Energy, Nevada Operations Office (DOE/NV); the State of Nevada Division of Environmental Protection (NDEP); and the US Department of Defense (FFACO, 1996). The CAIP is a document that provides or references all of the specific information for investigation activities associated with Corrective Action Units (CAUs) or Corrective Action Sites (CASs). According to the FFACO (FFACO, 1996), CASs are sites potentially requiring corrective action(s) and may include solid waste management units or individual disposal or release sites. Corrective Action Units consist of one or more CASs grouped together based on geography, technical similarity, or agency responsibility for the purpose of determining corrective actions. This CAIP contains the environmental sample collection objectives and the criteria for conducting site investigation activities at CAU 261, the Area 25 Test Cell A Leachfield System, which is located in Area 25 at the Nevada Test Site (NTS). The NTS is approximately 88 kilometers (km) (55 miles [mi]) northwest of Las Vegas, Nevada. As presented, CAU 261 is comprised of CASs 25-05-01 and 25-05-07, respectively known as the Leachfield and the Acid Waste Leach Pit (AWLP) (FFACO, 1996). The leachfield is an area with dimensions of approximately 23 by 17 meters (m) (75 by 55 feet [ft]) and is located south of Building 3124, which is southwest and adjacent to Test Cell A. Test Cell A was operational during the 1960s to test nuclear rocket reactors in support of the Nuclear Rocket Development Station (NRDS) (SNPO, 1970). Various operations within Building 3124, from 1962 through 1972, have resulted in liquid waste releases to the leachfield and the AWLP (DOE, 1988a). The surface and subsurface soils in the vicinity of the collection system and leachfield have potentially been impacted by radioactive and other contaminants of potential concern (COPCs) associated with decontamination activities of equipment from Test Cell A