Abstract: Case studies of regional landfills show that electromagnetic geophysical methods can accurately and inexpensively define boundaries and thickness of waste. Degradation of putrescible solid waste generates conductive leachate that can be imaged with a frequency-domain terrain conductivity meter. Terrain conductivity measurements can be modified through a simple algorithm based upon native soil conductivity to produce plan maps showing a detailed three-dimensional image of the waste mass. Further, seismic records and borings confirm that a linear relationship exists between measured waste terrain conductance and thickness of waste. Consequently, waste volume can be estimated to within 15% of the true mass volume by employing terrain conductivity mapping.
Keywords: geophysical methods; terrain conductivity; waste boundaries; waste thickness; waste volume
Electromagnetic terrain conductivity surveys have been useful for landfill investigations for many years. These inexpensive surveys can delineate waste, conductive fluids, and buried metal; and provide a three-dimensional overview of the buried waste. Degradation of organic material in field-saturated conditions produces a terrain conductance signature that is elevated above background conditions. The elevated signature, through simple mathematical operations, can locate waste, delineate the waste boundary and provide a rough estimate of depth of waste. The footprint of the landfill can be used with the terrain conductivity estimation of the depth to waste to calculate an in-place waste volume.