ELECTRICAL RESISTIVITY INVESTIGATION OF SOLID WASTE DISPOSAL SITE AT MAINTUMBI, MINNA, NIGER STATE

Abstract

Electrical resistivity survey was conducted at an old waste dumpsite in Maitunbi, Chanchaga Local Government Area of Niger State in Nigeria to determine leachate contamination to soils, and its possible contamination to subsurface groundwater. The study area is mostly characterised by three (3) layered geologic sections which includes topsoil, weathered basement and Fresh basement. Thirty-Six vertical electric sounding (VES) lines were measured in a grid format on six profiles with spacing of about 20m intervals. The equipment used was the Abem Terrameter “SAS 4000”, the data was analysed using computer processed methods with the following software; Winresist version 1.0 software, Surfer 10 software programmes. The analysis indicates that there was an ingress of leachate contaminant at the dumpsite with a very low resistivity of 20 Ωm to 60 Ωm as compared to that of control site of resistivities 200 Ωm to 850. The result shows that the leachate was localized at about 13m from the topsoil of the dumpsite and is spreading in the direction of the groundwater flow. However, considering the weathered/fractured layer thickness map, the aquifer is observed to be promising at the depth of 20 m. This suggests that the ground water is not contaminated. But if the migration continues at the current rate of 1.63 m/year, the ground water will be contaminated in 12.3 years from now if proper mitigation measures are not taken into consideration at the dumpsite.