Investigation of groundwater quality around municipal waste disposal site in Malete southwestern Nigeria

The study employed an integrated application of electrical resistivity tomography (ERT), soil classifications, and physicochemical parameters of water samples to map the extent and dynamics of leachate migration from the municipal waste dump and its potential impact on groundwater in a crystalline basement complex area, Malete, Nigeria. The ERT model revealed leachate dispersion beneath poorly graded inorganic silt-sand topsoil to about 2 m, hoisting low resistive moisturized soil within the range 1.8×10^-3 to 6.4×10^-1 Ωm and underlain by an impervious thin silty-clay layer (about 0.5-m thick) and weathered basement downward. The imprint of induced near-surface leachate percolation is revealed with increased (but acceptable) turbidity, conductivity, DO, and BOD within the shallow wells but prevented by the impervious silt–clay liner from vertical migration to the deeper water source. The concentrations of As, Cd, Cr, Fe, Pb, Zn, and Cu in the water samples and the acceptable TDS and TSS parameters; with low nitrate, sulfate and phosphate concentration are within the recommended range approved by WHO permissible limit for potable water and could have no adverse effects on the public’s health.