Integrated Geophysical, Geochemical, and Geospatial Investigation of Leachate Migration at Otofure Dumpsite, Benin City, Nigeria

Abstract

Dumpsites situated in groundwater recharge zones pose serious threats to nearby shallow aquifers. In this study, the potential for groundwater contamination around the Otofure Dumpsite in Benin City, Edo State, was assessed to guide sustainable waste management practices. A geoelectrical survey using an ABEM SAS 300C Terrameter with a dipole-dipole configuration and Vertical Electrical Sounding (VES) was conducted to evaluate subsurface resistivity and delineate geological formations. Soil samples were analyzed using X-Ray Fluorescence (XRF) spectrometry to determine elemental composition, and spatial distribution maps were created using Inverse Distance Weighting (IDW) interpolation. Results showed that leachate migration was primarily limited to the top 10 meters of soil, restricted by an underlying impermeable clay layer. The XRF analysis revealed that heavy metal concentrations were below permissible limits, indicating limited soil contamination and minimal risk to deeper groundwater. These findings support informed decision-making for dumpsite siting and environmental monitoring in vulnerable recharge areas.