This Corrective Action Investigation Plan contains the U.S. Department of Energy, Nevada Operations Office's (DOE/NV's) approach to collect the data necessary to evaluate corrective action alternatives (CAAs) appropriate for the closure of Corrective Action Unit (CAU) 487, Thunderwell Site, Tonopah Test Range (TTR), Nevada, under the Federal Facility Agreement and Consent Order. Corrective Action Unit 487 consists of a single Corrective Action Site (CAS), RG 26-001-RGRV, Thunderwell Site. The site is located in the northwest portion of the TTR, Nevada, approximately five miles northwest of the Area 3 Control Point and closest to the Cactus Flats broad basin. Historically, Sandia National Laboratories in New Mexico used CAU 487 in the early to mid-1960s for a series of high explosive tests detonated at the bottom of large cylindrical steel tubes. Historical photographs indicate that debris from these tests and subsequent operations may have been scattered and buried throughout the site. A March 2000 walk-over survey and a July 2000 geophysical survey indicated evidence of buried and surface debris in dirt mounds and areas throughout the site; however, a radiological drive-over survey also performed in July 2000 indicated that no radiological hazards were identified at this site. Based on site history, the scope of this plan is to resolve the problem statement identified during the Data Quality Objectives process that detonation activities at this CAU site may have resulted in the release of contaminants of concern into the surface/subsurface soil including total volatile and total semivolatile organic compounds, total Resource Conservation and Recovery Act metals, radionuclides, total petroleum hydrocarbons, and high explosives. Therefore, the scope of corrective action field investigation will involve excavation, drilling, and extensive soil sampling and analysis activities to determine the extent (if any) of both the lateral and vertical contamination and whether or not any such contamination extends beyond the historical boundaries of the site. The results of this field investigation will support a defensible evaluation of CAAs in the subsequent corrective action decision document.
