Cross Borehole Electromagnetic Imaging Of Chemical And Mixed Waste Landfills

The Mixed Waste Landfill integrated Demonstration (MWLID) is testing noninvasive<br>site characterization methods at several locations, including the Chemical Waste<br>Landfill (CWL) at Sandia National Laboratories. The CWL comprises shallow, unlined<br>pits that were used for the disposal of acids, oils, solvents, and inorganic compounds<br>from 1962 until the CWL was closed in 1985. The soils of the landfills are alluvial,<br>predominantly sand, gravels and cobbles with small quantities of silts and clays. The<br>focus of this study is an unlined chromic acid pit (LEAP). The UCAP pit is rectangular<br>(approximately 35 by 12 feet), which reported/y received unknown volumes of<br>chromium in the form of chromic acid (liquid) and other hazardous materials. At this<br>location, we have demonstrated a continuous waveform (CW) system for site charac-<br>terization. During this year, we will also utilize a crossborehole pulsed radar system.<br>Both methods are sensitive to variations in either electrical conductivity or dielectric<br>constant in the soils or host rock at a waste site. These earth properties are some of<br>the most responsive geophysical indicators of metallic, acidic and water-based subsurface<br>contaminants.