Evaluation of geophysical methods for characterizing industrial and municipal waste dumps.

The main aim of this study was to assess the suitability of geophysical methods for investigating old waste dumps. Electrical Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT), Multichannel Analysis of Surface Waves (MASW) and Ground Penetrating Radar (GPR) were the techniques used to characterize a waste dump in the town of Dąbrowa Górnicza (S Poland). GPR and SRT were the most difficult methods to use because of the dense vegetation, which attenuated the passage of electromagnetic and seismic waves to the ground. However, GPR did turn out to be an appropriate tool for characterizing variations in the surface cover. ERT, SRT and MASW clearly highlighted the transition between the waste deposit and the host sediments, and determined the approximate thickness of the waste deposits. With MASW, however, the waste type and the boundary between the waste layer and surface cover could not be delineated. In some places, the surface cover was identified using SRT. With both these methods, the problem with identification may be due to the small contrast in the S- and P-wave velocities through two kinds of waste (municipal and industrial), the thinness of the waste layer, and the considerable differentiation of the surface cover. The most accurate results regarding the waste deposits were obtained using ERT and different electrode spacings. ERT pinpointed the exact location of the stored waste, distinguished between the types of waste, and identified the soil cover. Data from shallow boreholes confirmed the interpretations of the methods.