Determination of Subsurface Sewage Contamination of Rocks and Water using 2-D Resistivity Imaging: A Niger delta University Teaching Hospital Case Study, Bayelsa state Southern Nigeria.

Abstract

Septic tanks as used in the management of sewage systems may result to both surface and/or subsurface (groundwater) pollution. While remediation and repairs of surface sewage spillage in septic tanks is feasible, the reverse is the case with subsurface pollution of porous media through sewage seepages. 2 D Electrical Resistivity Imaging (ERT) was used to determine the nature of sewage contamination of subsurface rocks in the premises of the Niger Delta University Teaching Hospital (NDUTH) Okolobiri in Bayelsa State, Southern Nigeria. It was observed that in the presence of contaminant fluids, geoelectrical resistivity signatures behave anomalously in most cases being more conductive than the clean rock/fluid system. Also, that contaminant fluid, in the course of time, finds its way into groundwater to alter the electrical and chemical properties of pristine rock/fluid as seen in this investigation. The observed subsurface contaminant (leachate) migrate in the direction of groundwater flow and decreases in concentration away from the source (septic tank) which in the current study is in the North South direction as represented in the 2 D resistivity contouring of the three (3) geoelectrical profiles in this report.