Groundwater Quality Assessment near an Open Dump Municipal Solid Waste Disposal Site in Ekiti State, Southwestern Nigeria

Abstract

This study assessed groundwater quality around an open dump municipal solid waste (MSW) disposal site at Ilokun, a village on the outskirts of Ado-Ekiti, Ekiti State, Nigeria. Three geotechnical boreholes and three water boreholes (tube wells) were drilled at intervals of 15m, 30m and 45m away from the disposal site. Soil samples were obtained near the top and at the bottom of the geotechnical boreholes. Tests carried out on these samples included the sieve analysis, specific gravity, bulk density, natural moisture contents, Atterberg limits, linear shrinkage, and hydraulic conductivity tests, and these were used to index and classify the soils at the landfill dumpsite. It was discovered that the soils belonged to the clay and clayey-sand USCS groups (CL and SC mainly). Groundwater samples were taken from the three water boreholes (tube wells), and physical, chemical and microbiological investigations carried out on the water samples and on water obtained from an existing hand-dug well in the neighbourhood of the dumpsite. The parameters obtained from the tests on the samples were compared with the Guidelines for Drinking Water Quality of the World Health Organisation (WHO) and the Nigerian Standard for Drinking Water Quality of the Standards Organisation of Nigeria. The water quality parameters determined included: the acidity (pH), temperature, electrical conductivity (EC), colour and odour, turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), total dissolved solids (TDS), total hardness (TH), and contents of the constituents such as total iron, chloride, sulphate, nitrate, etc. The microbiological characteristics determined are the Total Bacterial Count (Total coliform count), and the presence of Faecal streptococci, Staphylococcus aeurus and Escherichia coli. It was discovered that the groundwater at the dumpsite has been heavily contaminated and unfit for human consumption or usage without appropriate treatment to render them potable and fit for domestic use.