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Title: Annual Report RCRA Post-Closure Monitoring and Inspections for CAU 112: Area 23 Hazardous Waste Trenches, Nevada Test Site, Nevada, for the Period October 1999-October 2000

Technical Report ·
DOI:https://doi.org/10.2172/788700· OSTI ID:788700

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 1999-October 2000 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 August 2000. There has been no subsidence at any of the markers since monitoring began seven years ago. The objective of the neutron logging program is to monitor the soil moisture conditions along 30 neutron access tubes and detect changes that maybe indicative of moisture movement at a point located directly beneath each trench. Precipitation for the period October 1999 through October 2000 was 10.44 centimeters (cm) (4.11 inches [in.]) (U.S. National Weather Service, 2000). The prior year annual rainfall (January 1999 through December 1999) was 10.13cm (3.99 in.). The highest 30-day cumulative rainfall occurred on March 8, 2000, with a total of 6.63 cm (2.61 in.). The heaviest daily precipitation occurred on February 23,2000, with a total of 1.70 cm (0.67 in.) falling in that 24-hour period. The recorded average annual rainfall for this site, from 1972 to January 1999, is 15.06 cm (5.93 in.). 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.

Research Organization:
Bechtel Nevada Corporation (US)
Sponsoring Organization:
US Department of Energy (US)
DOE Contract Number:
AC08-96NV11718
OSTI ID:
788700
Report Number(s):
DOE/NV-693-Rev 1; TRN: AH200136%%129
Resource Relation:
Other Information: PBD: 1 Mar 2001
Country of Publication:
United States
Language:
English