IMPACT OF SOLID WASTE DUMP-SITES ON GROUNDWATER QUALITY IN BENIN CITY, NIGERIA

*Sam-Uroupa, R. E. | Edo State Ministry of Environment and Sustainability, Benin City, Nigeria

Abstract

Municipal waste dumpsites contain pollutants which are either water-solution or are capable of being moved along the path of water during percolation through the soil to groundwater. This study was therefore carried out to investigate the impact of solid waste dump-sites in Benin City on the receiving groundwater quality. Four stations were chosen for this study, with each station located within one Local Government Area. These stations were dump-sites at Ikhueniro (station 1), Costain (station 2) and Ugbioyoko (station 3). Omaghe (station 4) was used as the control station without waste dumpsite. Soil samples were collected at three distances from the dump-sites of 0-50m, 50-100m, >100m at 0-30cm depth of top soil and analyzed while the boreholes used were within 120m radius from the dump-sites. This investigation spanned from July 2011 to December 2011. Results showed that water samples were found to be enriched with heavy metals (Fe, Mn, Zn, Cu, Cr, Pb, Ni and V) more than the control water sample; these were however within WHO and FMEnv. regulatory limits for drinking water. The mean pH values of the sampled water fluctuated between 4.50 and 5.57 and were not within the WHO and FMEnv. regulatory limits of 6.5 to 8.5 set for drinking water. ANOVA revealed a highly significant difference (p < 0.01) between the means of the following water parameters; Ca, Na, K, Mg, electric conductivity, Salinity, HCO₃, and total soluble solids. The Kruskal-Wallis Test revealed that aerobic bacterial count was significant (p < 0.05) with the highest mean value in station 1 (17.17 x10² cfu/ml) and lowest mean value in station 4 (6.00x10² cfu/ml). Seasonal pattern of variations was observed for water samples examined.