Study of FEM Method Sensitivity to Detect Leachate Infiltration

Study of FEM Method Sensitivity to Detect Leachate Infiltration

A Frequential Electromagnetic (FEM) survey was carried out in a dumpsite of waste. The dumpsite lies on a lateritic layer above an unconfined sand aquifer with water table at 14–19m depth. This study is focused on the evaluation of 1D Electromagnetic (EM) method sensitivity to detect the leachate infiltration. Synthetic models have been built to test various medium. The PCLOOP software has been used for direct calculation and FreqEM software for reverse calculation of the models. The obtained 1D calculated model has showed that EM method detects perfectly all the layers of distinct conductivities. Nevertheless, the method under-estimates of 8% the values of conductivities and over-estimates of 6% those of thicknesses of the layers. A field test of this sensitivity to detect layers has been done on a dumpsite. The models of ground on the dumpsite showed that in the unpolluted zones the leachate did not reach the water table and in the polluted zones, the water table is polluted by the leachate. EM method is sensitive to the detection of the leachate infiltration in the point of survey. However, this sensitivity decreases with the increase of the computing heterogeneous volume.