VULNERABILITY ASSESSMENT OF BOREHOLES LOCATED CLOSE TO LEMNA LANDFILL IN CALABAR METROPOLIS, NIGERIA (Published)
Solid waste mostly garbage, agriculture and industrial waste are disposed in landfills where it decomposes and produces a leachate that can contaminate underlying groundwater. Waste management has remained an undisputable environmental problem in Nigeria. This has manifested in the form of indiscriminate disposal of wastes and illegal landfills and dumps along main roads and streets, and the problem is compounded by the generation of enormous quantities of waste. In the developing world such as Nigeria, borehole water users hardly treat water before usage and this poses a serious threat to their health since the utilized this untreated water for consumption, domestic uses, agriculture and industrial purposes. Groundwater studies have ascertained that leachates from landfill migrate in the direction of groundwater flow to contaminate the underlying aquifer. The study assessed the vulnerability of borehole located close to Lemna dumpsite in Calabar Municipality. Borehole water samples were collected from ten designated boreholes and their physicochemical parameters were analysed. The length, breadth and depth of the landfill were measured with a tape and meter rule. The length of the landfill was 960m, the width 430m and the depth 180m. Geographical positioning system (GPS) was used to obtain the static water level from where the groundwater flow map was deduced. Parameters such as BOD, DO, Fe2+, Ni2+, Zn2+, faecal and total coliform count values when compared with world health organization standard (WHO) were seen to exceed the recommended value. The research revealed that groundwater flow from the North to South, carrying along with it dissolved waste materials and leachates which infiltrates into the borehole water and contaminates it, thereby rendering it unsuitable for drinking and domestic use. The researchers therefore suggested that the base of landfills should be properly coated with concrete or cellophanematerials to avoid leachates infiltrating into the groundwater. Recycling of municipal waste, proper education and awareness on solid waste management should be encouraged in the study area.