ABSTRACT
The research was carried out to characterize the lithostratigraphic units and evaluate the physiochemical parameters of selected borehole water samples around open dumpsites in Oluku, Edo State. The average pH of water samples in the study area is 5.3, which is below the permissible limit of 6.5–8.5 (WHO, 2007), which implies that the water is slightly acidic. The EC and TDS values in the study were below the permissible limit of 900 uS/cm but were also below the maximum permissible TDS limit of 1000 mg/l (WHO, 2007). The study also revealed that the sulphate concentrations (20.12–25.6) in the area were within the recommended standard of 120 mg/l (WHO 2007). The results from VES revealed that VES 1 has 8 geo-electric sections, with the first layer interpreted as top soil with a resistivity of 396 ꭥm and thickness of 0.99 m. the second layer was lateritic soil, while layers 3,4,5,6,7, and 8 were interpreted as sandy clay, fine sand, clay, fine to medium sand, medium to coarse sand and fine to medium sand with resistivities of 394.69, 571.35, 221.65, 649.74, 1379.9 and 650.12 ohms/meter. Findings show that the thickness of clay overburdened is higher than other geo-electric layers and can serve as a natural treatment system against infiltrating contaminants that threaten groundwater in the area. The study has presented the results of a physico-chemical and lithological unit at the Oluku dumpsite in Ovia, North East, and Benin City. It can be concluded that ground water in the study area has not been significantly impacted by the dumpsite. The study area was probably due to the attenuation effect of the geologic units.
