DETERMINING AREAL EXTENT, COVER, AND VOLUME OF WASTE FILLS USING GEOPHYSICS FOR LAND USE PLANNING

Induced polarization has been used in concert with electrical resistivity imaging for several years to quantify physical and some environmental parameters in buried waste fills. The physical properties these methods measure are very different but often complementary. Three case histories from the eastern U.S. show how the methods have been used in land use planning. Each of the projects illustrates different aspects of how the information can be used. Whereas cheaper electromagnetic method may help define the perimeter of the fill, induced polarization has the ability to determine thickness and cover accurately. Conversely, resistivity data was useful in these cases to help define the underlying geologic conditions and the location of downward migrating leachate at the sites, which was not as readily identified in the electromagnetic or induced polarization data. The thickness and geologic information were used to help: estimate differential settlement, determine what kinds of structures could be constructed over the fills, the most effective location for structures near the fills, and to develop environmental action plans for regulatory review. Also of interest is that these fills have slightly different manifestations in the geophysical data than many in the more arid portions of the U.S.