Post-Closure Report for Closed Resource Conservation and Recovery Act Corrective Action Units, Nevada National Security Site, Nevada, For Fiscal Year 2010

This report serves as the combined annual report for post-closure activities for the following closed Corrective Action Units (CAUs): (1) CAU 90, Area 2 Bitcutter Containment; (2) CAU 91, Area 3 U-3fi Injection Well; (3) CAU 92, Area 6 Decon Pond Facility; (4) CAU 110, Area 3 WMD U-3ax/bl Crater; and (5) CAU 112, Area 23 Hazardous Waste Trenches. The locations of the sites are shown in Figure 1. This report covers fiscal year 2010 (October 2009-September 2010). The post-closure requirements for these sites are described in Resource Conservation and Recovery Act Permit Number NEV HW0021 and summarized in each CAU-specific section in Section 1.0 of this report. Site inspections are conducted semiannually at CAUs 90 and 91 and quarterly at CAUs 92, 110, and 112. Additional inspections are conducted at CAU 92 if precipitation occurs in excess of 0.50 inches in a 24-hour period. Inspections include an evaluation of the condition of the units and identification of any deficiencies that may compromise the integrity of the units. The condition of covers, fencing, signs, gates, and locks is documented. In addition, soil moisture monitoring and subsidence surveys are conducted at CAU 110. The results of the inspections, summary of maintenance activities, results of vegetations surveys, and analysis of monitoring data are presented in this report. Copies of the inspection checklists are included as Appendix A. Field notes completed during each inspection are included in Appendix B. Photographs taken during the site inspections are included in Appendix C