Influence of Leachate on Groundwater Quality in Sagamu Ne, Southwestern Nigeria

Leachate from landfills and waste deposit sites contain high amount of toxic elements leading to the pollution groundwater in the study area. The study examines the impact of leachate from landfill sites on the quality of groundwater. Twelve groundwater samples, consisting of seven hand-dug wells and five boreholes, were analyzed for their major ionic components. Mean concentration of pH 5.89 was found to be lower than the WHO 2006 and USEPA 1986 permissible limits. Total dissolved solid(TDS), electrical conductivity(EC) and alkalinity were found to be within the permissible limits. The mean concentrations of major cations, Na, Ca, K, Mg, Fe, anions, HCO₃, Cl^-, NO₃^-, SO₄^2- and heavy metals were found to be within the permissible limits with the exception of Mn. The high concentration of Mn was due to the influx of leachate in the landfill into groundwater. Furthermore, the moderately high values ofCl^- and NO₃^-could be attributed to the impact of leachate from the abattoir found around the dumpsite area. Therefore, there is need for drinking water quality assessment to determine the suitability of groundwater for domestic and industrial consumption.