2-D Electrical Resistivity Survey and Physiochemical/ Microbial Analysis of Groundwater around the Central Septic Tank within Female Hostels, University of Benin, Ugbowo Campus, Benin City, Nigeria

Abstract

Two dimensional (2-D) Electrical Resistivity survey was employed to investigate the presence of contaminants plume around central septic tank within Female Hostels in University of Benin, Ugbowo Campus, Benin City. The investigation was carried out by using the Wenner alpha configuration using the PASI resistivity meter. RES2D Inversion software was used for interpretation of the three traverses that were covered so as to delineate the plume and probable trend of migration of leachate in the study area. Both physiochemical and microbial analyses were carried out on borehole-water collected within the study area. The 2-D inversion model for traverse 1 revealed that the zone with low resistivity of 90Ωm was indicated in the topsoil at the lateral distance of 95m to 100m at a depth of 6m to the subsurface. In the second and third layers of traverses 2 and 3 with lateral distance of 40 to 95m is suspected to be leachate saturation that leaked from the septic tank. The study also revealed that other physiochemical analysis of the heavy metals lie within standard value except pH value of 5.55 which is below WHO standard indicating that the site is acidic, but the result of microbial analysis gave a value 2.8 × 106ml which is above the standard specification for drinking water. Therefore, the study showed that leachate exists and pose a threat to groundwater in the study location.