USING REAL-TIME VADOSE ZONE MONITORING FOR LONG-TERM PERFORMANCE ASSESSMENT OF A CORRECTIVE ACTION MANAGEMENT UNIT CONTAINMENT CELL SANDIA NATIONAL LABORATORIES, NEW MEXICO

摘要

Sandia National Laboratories in Albuquerque, New Mexico (SNL/NM), operates a Corrective Action Management Unit (CAMU) for the United States Department of Energy (DOE). In 1997 SNL/NM was granted a permit modification that allowed construction and operation of a CAMU. The CAMU follows regulatory guidance that facilitates expedient and cost-effective cleanup and management of hazardous remediation wastes. Treatment operations were completed in January 2003 in conjunction with containment of 845,000 cubic feet (23,930 cubic meters) of treated soil. The containment cell is situated approximately 485 feet (148 meters) above groundwater in a semiarid region marked by low rainfall and high evapotransporation. These site conditions required a unique approach to monitoring the containment cell performance and ultimately protecting groundwater. To satisfy Resource Conservation and Recovery Act groundwater monitoring requirements, a Vadose Zone Monitoring System (VZMS) for rapidly detecting leaks was incorporated into the containment cell design. One component of the VZMS, the Primary Subliner (PSL) monitoring system, utilizes the containment cell subliner to focus potential leakage into five longitudinal trenches. Each trench contains a wicking material and a vitrified clay pipe used to provide access for a neutron probe to measure soil moisture content directly under the containment cell. The other component of the VZMS, the Vertical Sensor Array (VSA), consists of 22 time-domain reflectometers that provide a backup to the PSL.