Geophysical Evaluation of a Landfill Site in Ikpoba Okhia Local Government Area, Edo State, Nigeria

Abstract

Electrical resistivity tomography (ERT) technique has been used in this research to evaluate the contamination zones at a dumpsite in Benin City. Three electrical resistivity profiles were established for the purpose of the research. The pseudosection maps and the apparent resistivity values helped in identifying the nature and depth of the conductive sources in the study area. The field survey was carried out using Dipole-dipole array with a spread of 164 m at Ikpoba Okhia local government approved dumpsite in Benin City, Edo State. The ERT method revealed highly conductive zones of less than 20 Ωm of leachate to the depth of 39.4 m. The area shows subsurface resistivity distribution at the Eastern part of the study area trending East with prominence at the center and distributed North - East which has been interpreted as fractured or migration zones of leachate. The depth estimate revealed the apparent depth to the causative body from the surface with depth range from 0.34 m to 39.4 m which agrees with other literatures. The study has revealed that the area is generally highly conductive due to the presences of toxic elements while the fractured zones are prospective locations for infiltration of contaminant plums (leachate).