Electrical Resistivity Tomography Investigation of Groundwater Contamination Pathway at Ahmadu Bello University Sewage Treatment Site.

Abstract

The Two-dimensional electrical resistivity survey using Schlumberger array at 5m electrode spacing was carried out along three profiles at the Ahmadu Bello University sewage treatment site. The study aims to investigate the possible fracture and permeable zones that serve as the pathways for groundwater contamination. The ABEM SAS4000 terrameter was used in data collection. The field data obtained has been analyzed using RES2DIV inversion software which gives an automatic interpretation of apparent resistivity. The geologic sequence beneath the study area is composed of topsoil, weathered basement and fracture basement layers. The resistivity value of the first layers ranges from 15Ωm to 58Ωm, 12Ωm to 40Ωm and 9Ωm to 14Ωm. The low resistivity variations in the topsoil identify the presence of contaminated plume zones in the layer. However, the fracture basement underlying the weathered basement shows lateral variation in the basement resistivity. The result shows that the contaminated plume zones has the tendency to contaminate the groundwater