Corrective Action Investigation Plan for Corrective Action Unit 567: Miscellaneous Soil Sites, Nevada National Security Site, Nevada, with ROTC 1 Revision 0

Corrective Action Unit (CAU) 567 is located in Areas 1, 3, 5, 20, and 25 of the Nevada National Security Site, which is approximately 65 miles northwest of Las Vegas, Nevada. CAU 567 is a grouping of sites where there has been a suspected release of contamination associated with nuclear testing. This document describes the planned investigation of CAU 567, which comprises the following corrective action sites (CASs): • 01-23-03, Atmospheric Test Site T-1 • 03-23-25, Seaweed E Contamination Area • 05-23-07, A5b RMA • 20-23-08, Colby Mud Spill • 25-23-23, J-11 Soil RMA These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the investigation report. The sites will be investigated based on the data quality objectives (DQOs) developed on May 6, 2013, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Field Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 567. The site investigation process will also be conducted in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices to be applied to this activity. The potential contamination sources associated with CAU 567 releases are nuclear test operations and other NNSS operations. The DQO process resulted in an assumption that total effective dose (TED) within a default contamination boundary at Atmospheric Test Site T-1 exceeds the final action level (FAL) and requires corrective action. The presence and nature of contamination outside the default contamination boundary at Atmospheric Test Site T-1 and all other CAU 567 CASs will be evaluated based on information collected from a field investigation. Radiological contamination will be evaluated based on a comparison of the TED at sample locations to the dose-based FAL. The TED will be calculated as the total of separate estimates of internal and external dose. Results from the analysis of soil samples will be used to calculate internal radiological dose. Thermoluminescent dosimeters placed at the center of each sample location will be used to measure external radiological dose. Appendix A provides a detailed discussion of the DQO methodology and the DQOs specific to each CAS