Investigating Groundwater Quality around Olusosun Dumpsite, Lagos State, Nigeria

Olusosun dumpsite, established in 1992 and reputed to be one of Africa's largest open dumps covering an area of 42 hectares, is situated at Ojota in Kosofe Local Government Area (LGA) of Lagos State, Nigeria. Originally, the dumpsite was located on the outskirts of the Lagos metropolis, but due to rapid urban development, the site is now surrounded by residential, commercial and industrial suburbs. Established literature has indicated that water borne diseases such as typhoid, dysentery, fatigue and cholera are amongst the ailments mostly suffered by inhabitants within the vicinity of the dumpsite. Groundwater quality was investigated around Olusosun dumpsite, Lagos State, Nigeria, by collecting nineteen representative water samples from sixteen wells and three boreholes, and a leachate sample from the landfill. The samples were examined in the laboratory for physical, chemical and bacteriological analyses using standard laboratory procedures. The obtained values of concentration of key parameters in all sampled wells were plotted against distances from the Olusosun dumpsite, in scatter diagrams. Unexpectedly, the concentration did not follow any attenuation pattern, with increasing distance up to the farthest sampled well. It is implied from the outcome of the exercise that there are other contributory sources to the pollution of groundwater in the area, which must be discovered. An immediate solution to the groundwater pollution in the area is thus complex, and may require a more drastic and holistic approach. It is therefore recommended that in the interim, the Lagos State Government of Nigeria should urgently provide an alternative source of water supply towards meeting the immediate water needs of inhabitants of the area, while adopting a pragmatic approach to remediate the problem. This will go a long way in reducing the prevalence of waterborne diseases around Olusosun dumpsite.