Geoelectrical Imaging and Physicochemical Assessment of Waste Dumpsite: Implications on Groundwater Quality

The most unregarded cause of water pollution is the inappropriate dumping of wastes and improper treatment of solid wastes. The current research examined the impacts of a solid waste disposal site on water quality of the residential areas bounded by the site by integrating 2-D resistivity imaging, physical, chemical and bacteriological analyses of water samples from twelve hand-dug wells (HdW) and two boreholes (BH) using standard field and laboratory procedures. The results of the 2-D resistivity imaging of the subsurface along four traverses around the refuse dumpsite showed anomalously low resistivity zones, intermediate resistivity zones and high resistivity zones interpreted to be soil or sand saturated with contaminant leachate, rock materials having varying moisture content and composition and rock materials contaminated with dumpsite gases, respectively. The study observed that these contaminants have migrated to the depth of 25 m below the aquifer and over 20 m distance away from the edge of the dumpsite. Apart from nitrate, phosphate and turbidity, all the other physicochemical parameters tested were within the WHO recommended limits. However, the trace metals (Fe, Mn, Cr, Pb and Zn) and the total bacteria count were generally above the recommended limit. Consequent upon the associated health implications due to elevated levels of some of the contaminants, which were attributed mainly to leachate from the dumpsite, the study suggested adequate corrective measures and a programme enlightenment campaign to all end users.