Closure Report for Corrective Action Unit 539: Areas 25 and 26 Railroad Tracks Nevada National Security Site, Nevada with ROTC-1, Revision 0

Abstract

This Closure Report (CR) presents information supporting the closure of Corrective Action Unit (CAU) 539: Areas 25 and 26 Railroad Tracks, Nevada National Security Site, Nevada. This CR complies with the requirements of the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the State of Nevada; U.S. Department of Energy (DOE), Environmental Management; U.S. Department of Defense; and DOE, Legacy Management. The corrective action sites (CASs) within CAU 539 are located within Areas 25 and 26 of the Nevada National Security Site. Corrective Action Unit 539 comprises the following CASs: • 25-99-21, Area 25 Railroad Tracks • 26-99-05, Area 26 Railroad Tracks The purpose of this CR is to provide documentation supporting the completed corrective actions and provide data confirming that the closure objectives for CASs within CAU 539 were met. To achieve this, the following actions were performed: • Reviewed documentation on historical and current site conditions, including the concentration and extent of contamination. • Conducted radiological walkover surveys of railroad tracks in both Areas 25 and 26. • Collected ballast and soil samples and calculated internal dose estimates for radiological releases. • Collected in situ thermoluminescent dosimeter measurements and calculated external dose estimates for radiological releases. • Removed lead bricks as potential source material (PSM) and collected verification samples. • Implemented corrective actions as necessary to protect human health and the environment. • Properly disposed of corrective action and investigation wastes. • Implemented an FFACO use restriction (UR) for radiological contamination at CAS 25-99-21. The approved UR form and map are provided in Appendix F and will be filed in the DOE, National Nuclear Security Administration Nevada Site Office (NNSA/NSO), Facility Information Management System; the FFACO database; and the NNSA/NSO CAU/CAS files. From November 29, 2010, through May 2, 2011, closure activities were performed as set forth in the Streamlined Approach for Environmental Restoration (SAFER) Plan for Corrective Action Unit 539: Areas 25 and 26 Railroad Tracks, Nevada Test Site, Nevada. The purposes of the activities as defined during the data quality objectives process were as follows: • Determine whether contaminants of concern (COCs) are present. • If COCs are present, determine their nature and extent, implement appropriate corrective actions, and properly dispose of wastes. Analytes detected during the closure activities were evaluated against final action levels (FALs) to determine COCs for CAU 539. Assessment of the data generated from closure activities revealed the following: • At CAS 26-99-05, the total effective dose for radiological releases did not exceed the FAL of 25 millirem per Industrial Area year. Potential source material in the form of lead bricks was found at three locations. A corrective action of clean closure was implemented at these locations, and verification samples indicated that no further action is necessary. • At CAS 25-99-21, the total effective dose for radiological releases exceeds the FAL of 25 millirem per Industrial Area year. Potential source material in the form of lead bricks was found at eight locations. A corrective action was implemented by removing the lead bricks and soil above FALs at these locations, and verification samples indicated that no further action is necessary. Pieces of debris with high radioactivity were identified as PSM and remain within the CAS boundary. A corrective action of closure in place with a UR was implemented at this CAS because closure activities showed evidence of remaining soil contamination and radioactive PSM. Future land use will be restricted from surface and intrusive activities. Closure activities generated waste streams consisting of industrial solid waste, recyclable materials, low-level radioactive waste, and mixed low-level radioactive waste. Wastes were disposed of in the appropriate onsite landfills. The NNSA/NSO provides the following recommendations: • Clean closure is required at CAS 26-99-05. • Closure in place is required at CAS 25-99-21. • A UR is required at CAS 25-99-21. • A Notice of Completion to the NNSA/NSO is requested from the Nevada Division of Environmental Protection for closure of CAU 539. • Corrective Action Unit 539 should be moved from Appendix III to Appendix IV of the FFACO.