Hydro-geochemical characterization and water quality appraisal of groundwater in areas adjoining primordial landfills in the Maastrichtian Lafia Formation, Middle Benue Trough

This study assessed the groundwater quality in areas adjoining primordial landfills in Lafia town and its suitability for drinking purposes. Physico-chemical properties of twenty groundwater samples collected from boreholes, unlined and lined hand-dug wells at twenty different locations around three dumpsites were analysed for the appraisal of the water quality. Results of measured physical parameters show pH values in the range of 5.13–7.30, electrical conductivity (EC) values as between 89 and 7754 µS/cm and total dissolved solids (TDS) values that ranges from 59.63 to 5195 mg/L. The major cation and anions have mean concentrations in the order Ca2+  > Na+  > K+  > Mg2+ and SO42− > HCO3− > Cl− > CO3−. The Piper plot reveals three dominant water types (Ca–Cl–SO4, Ca–Na–HCO3−, and Na–Cl–SO4). Heavy metal pollution assessment reveals relatively higher modified heavy metal index (m-HMI) values for wells of close proximity to the landfills. The water quality index (WQI) classification reveals 35% of the groundwater sampled locations have water categorized as unsuitable for drinking purposes, 30% of the groundwater samples categorized as very poor and 25% of the groundwater samples classified as poor. While groundwater categorized as good to excellent constituted only 10% of the total groundwater samples analysed.