Hydrogeochemical Assessment of Dumpsite Leachate Impact on Groundwater Quality in Igbatoro, Akure, Southwestern Nigeria

This research examines the hydrogeochemical effects of leachate contamination on groundwater and surface water quality in the vicinity of the Igbatoro dumpsite in Akure, southwestern Nigeria. The study’s primary purpose was to assess the extent of physicochemical and bacteriological pollution resulting from improper waste disposal in a rapidly urbanising area. A grid sampling approach was employed to collect five water samples, consisting of four hand-dug wells and one surface water stream, at radial distances ranging from 197 m to 975 m from the landfill. These samples were analysed for various parameters using standard APHA methods and compared against the WHO and Nigerian Standard for Drinking Water Quality (NSDWQ) guidelines. Main findings revealed that groundwater is slightly acidic, with pH values (5.65–6.80) often falling below the permissible limit of 6.5–8.5. Elevated concentrations of Total Dissolved Solids (TDS) and Electrical Conductivity (EC) were observed, particularly in sample A5, which reached 901 mg/L and 1801 µs/cm, respectively. Most significantly, bacteriological analysis identified harmful pathogens, including faecal coliforms and Staphylococcus species, in multiple samples. Specifically, faecal coliform counts reached as high as 68 cfu/100mL, far exceeding the mandatory limit of 0 cfu/100mL. Statistical evaluations, including Principal Component Analysis (PCA), confirmed that leachate infiltration is the primary driver of ionic enrichment in the local aquifer. The study concludes that the Igbatoro dumpsite poses a significant threat to public health and the environment. It is recommended that the open dumpsite be replaced with an engineered sanitary landfill and that a minimum protective radius of 500 meters be maintained for future borehole development.