GEOELECTRICAL INVESTIGATION FOR LEACHATE PLUME MIGRATION ON MAITUMBI DUMP SITE, MINNA, NIGER STATE, NIGERIA Authors

Abstract

Leachate contamination due to poor solid waste management causes serious negative effects on the environment and human health. In this work, resistivity method was employed at an old dumpsite in Maitumbi, Minna, Niger State, Nigeria to study the ingress of leachate contamination into groundwater. The study area is mostly characterized by three (3) layered geologic sections, which include topsoil, weathered basement and Fresh basement. The Results indicate the ingress of leachate into the subsurface up to the depth of about 13 m. It was observed that the subsurface is contaminated by leachate migration. At the surface of the dump site, the resistivity value ranges from 20 Ωm to 40 Ωm as compared to that of the control site which ranges from 380 Ωm to 820 Ωm at the same depth. This indicates that the topsoil has been contaminated by leachate from the dump site. At 10 m depth, the resistivity value ranges from 20 Ωm to 60 Ωm at the dumpsite and that of the control site ranges from 260 Ωm to 580 Ωm. The low resistivity at this depth on the dumpsite compared to the control site further indicates the presence of leachate. At the depth of 13 m, the resistivity value at the dump site ranges from 100 Ωm to 850 Ωm and that of the control site ranges from 200 Ωm to 850Ωm. The similarity in resistivity value at this depth is indicative that the migration of leachate ends at the depth of 13 m. However, considering the weathered/fractured layer thickness map, the aquiferis observed to be promising at the depth of 20 m. This suggests that the groundwater is currently not affected by the leachate contamination. Nonetheless, the continuous migration of the leachate at the current rate of 1.63m/year, is estimated to result in the eventual contamination of the groundwater in 12.3 years. Keywords: Leachate contaminant, resistivity, landfill, aquifer, solid waste.