Soils and water in Ilokun area prune to contamination via the leachate emanating from a nearby waste dump. Hence, assessment of Ilokun waste dump in Ado-Ekiti, was carried out using vertical electrical sounding (VES) and 2-D electrical resistivity methods with a view to delineate various subsurface lithologies, obtain imagery of the subsurface and the leachate contaminant plumes. A total of seven VES stations were occupied while the dipole-dipole technique was carried out along three different traverses across the waste dump site. Both partial curve matching and computer iteration were used in the interpretation of the data obtained from the soundings. Results of the interpreted data revealed KQH, KH, QHA, H, KHK, QKHA, HKH curve types respectively. The VES interpretation indicated three to five geo-electric layers comprising of topsoil, lateritic soil, weathered layer and fractured/fresh basement. The weathered layer had the lowest resistivity (26 – 89Ωm) signifying evidence of leachate from the dumpsite percolating into the subsurface. The 2-D resistivity structure showed that the topsoil and the weathered layer virtually merged and characterized by relatively low resistivity of <40Ωm. The relatively low resistivity values in the weathered layer were as a result of high degree of leachate saturation. Traverse 1 showed the lateral flow of leachate plume from about 25m to 100m while traverses 2 and 3 revealed a hollow with more dumpsite weathered layer of low resistivity oriented along North – South direction of the study area. The groundwater within the vicinity of the investigated dumpsite has been contaminated to an estimated depth of about 25m thick with leachate flowing in the east to western direction of the waste dumpsite. This study has determined the extent of groundwater contamination indicating the northern part of the study area to be uncontaminated and suitable for hand dug well and borehole drilling.
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