Geoscience Investigation of selected sites in Minna for siting a Sanitary Landfill

Abstract

An integrated geoscience investigation was carried out on 3 selected sites in Minna, North-Central Nigeria in order to determine their suitability for use as sanitary landfill. Geological and hydrogeological mapping of the area was executed to determine the rock type and aquifer properties of the area. Subsurface geophysical investigations of the area employing the 1-D and 2-D subsurface resistivity imaging techniques were undertaken. Four lithological layers: lateritic top soil, mottled zone, clayey soil and the weathered to fresh basement rock were delineated from the geo-electric sections. The clay layer thickness varies between 2.8m to 8.0m with resistivity range of 18 ?m to 86 ?m and the depth of about 3.8m to 9.3m. The 2-D resistivity images using Wenner-Schlumberger and Wenner-Alpha arrays revealed the presence of an overwhelmingly dominant clay interval in the subsurface. The grain size distribution curve showed that the soil is dominated by fines (clay and silt. The soils liquid limit, plastic limit and plasticity index values ranged between 20 % to 90 %, 13.2 % to 26.8 % and 11.3 % to 24.7 % respectively. This implies that the soil is of low hydraulic conductivity. Permeability coefficient of the soils ranged from 3.4 x 10-6 cm/s to 5.68 x 10-8 cm/s, which is within the 10-8 to 10-6 range required for attenuation of leachate by natural geological materials with no potential of lateral migration of leachate. The analysis of results from geological, hydrogeological, geophysical, geotechnical and structural investigations revealed that two out of the three sites are suitable for siting a sanitary landfill.