Waste thickness estimation at a large landfill in Brazil from a comparison of simultaneous inversion of different electrode arrays data set

Abstract Electrical resistivity tomography (ERT) is particularly suitable for stratigraphic characterization of landfills given its sensitivity to the conductive response of leachate from solid waste. In this context, the simultaneous inversion of data from more than one electrode array can be more reliable than the single inversion of a single set of this data. In this way, resistivity lines were acquired in four electrode arrays at the Jockey Clube landfill in Brazil. We carried out the simultaneous inversion of all possible combinations of the Dipole-dipole (DD), Pole-dipole (PD), Wenner (WN) and Wenner-Shlumberger (WS) arrays and compared the results with direct information from 5 drill holes. The participation of the WN and WS electrode array data obtained similar results when grouped, and the WN and DD matrices, when inverted together, favored the horizontal resolution and the depth of investigation when compared with the inversion of the array separately. To estimate the depth of the waste layer, all available information was used to produce a geoelectric model based on the interpolation of approximate resistivity isovalues at the top and bottom of the waste landfill. The model points to a layer of waste that can vary from 30 to 65 meters in depth, and a total volume of 23,340,429 m³. Finally, the simultaneous inversion of arrays can be a useful tool for landfill investigation, especially if the geoelectric models of the matrices are quite different from each other, in which the subsurface structure is complicated with little a priori information.