Geohydrological Characteristics of Landfills to Groundwater Sensitivity: A Case of Oti Landfill Site, Kumasi.

Abstract

Soil plays a crucial role in preservation of groundwater resources from contamination and pollution. In view of this, the study focused on the geophysical and chemical condition of the Oti landfill soil and also assessed the physicochemical characteristics of local groundwater and leachate. The groundwater quality assessment tool was used to assess the impact of the Oti landfill site on the local groundwater. Systematic, grab and quartering sampling techniques were used to sample the soil, leachate and groundwater. On the leachate and groundwater samples, in-situ measurements were made to record the pH, EC and TDS concentration. Three different pits with depth 150 cm each were dug at the landfill site and three different samples were taken from each pit at varying depths. Samples were taken to the laboratory under a temperature below 4OC. Parameters that were analysed included K+, Ca2+, Mg2+, Na+, Al3+, BOD, COD, DO and some selected heavy metals including Fe3+, Zn, Cu, Mn, As, Cd, and Pb. Results obtained from the groundwater samples showed that the water was still in a good condition for usage. Hydrogeophysical data of the study area was also collected and the DRASTIC model was used to generate a DRASTIC vulnerability index in assessing how vulnerable the local groundwater was to pollution and also to validate the laboratory results. Both the vulnerability and sensitivity analysis results validated the laboratory results showing that the landfill has had no negative effect on the local groundwater system.