Annual Report RCRA Post-Closure Monitoring and Inspections for CAU 112: Area 23 Hazardous Waste Trenches, Nevada Test Site, Nevada, for the period October 2000-July 2001

摘要

This annual Neutron Soil Moisture Monitoring report provides an analysis and summary for site inspections, meteorological information, and neutron soil moisture monitoring data obtained at the Area 23 Hazardous Waste Trenches Resource Conservation and Recovery Act (RCRA) unit, located in Area 23 of the Nevada Test Site, Nye County, Nevada, during the October 2000--July 2001 monitoring period. Inspections of the Area 23 Hazardous Waste Trenches RCRA unit are conducted to determine and document the physical condition of the covers, facilities, and any unusual conditions that could impact the proper operation of the waste unit closure. Physical inspections of the closure were completed quarterly and indicated that the site is in good condition with no significant findings noted. An annual subsidence survey of the elevation markers was conducted in July 2001. There has been no subsidence at any of the markers since monitoring began eight years ago. Precipitation for the period October 2000 through July 2001 was 9.42 centimeters (cm) (3.71 inches (in)) (U.S. National Weather Service, 2001). The prior year annual rainfall (January 2000 through December 2000) was 10.44 cm (4.1 1 in.). The recorded average annual rainfall for this site from 1972 to January 2000 is 14.91 cm (5.87 in.). The objective of the neutron logging program is to monitor the soil moisture conditions along 30 neutron access tubes and detect changes that may be indicative of moisture movement at a point located directly beneath each trench. All monitored access tubes are within the compliance criteria of less than 5 percent residual volumetric moisture content at the compliance point directly beneath each respective trench. Soil conditions remain dry and stable underneath the trenches.