Assessment of the Impact of Open Waste Dumpsites on Groundwater Quality: A Case Study of the Onibu-Eja Dumpsite, Southwestern Nigeria

This research study assessed the impact of an open dumpsite on the quality of surface and shallow groundwater within its vicinity. Twenty water samples were collected and analyzed for physicochemical parameters, major ions, and trace metals. All major ions revealed concentrations within the acceptable limits of both standards, except chloride and sodium in some of the wells, probably due to addition of a disinfectant (“water guard”) and weathering of feldspars that characterize the basement rocks. For most of the trace metals, the concentrations were below detectable limits, except for zinc, iron, and manganese. However, iron and zinc concentrations fall well within the acceptable limit of both WHO and NSDWQ standards, while manganese concentrations were above the limit in most of the surface and shallow groundwaters downslope of the dumpsite. This could be attributed to leachates from the waste.