Geotechnical assessment of lateritic soils from a dumpsite in Ilorin (southwestern Nigeria) as liners in sanitary landfills

Abstract

This study was carried out to evaluate the impact of leachate from open landfill in the Ita-Amo area of Ilorin, southwestern Nigeria, on the immediate soil. It is also aimed at assessing the suitability of the soil as liners/barrier to prevent pollution of undergroundwater. Specific parameters, such as grain size distribution, Atterberg consistency limit, density and coefficient of permeability, to assess soil as liner in landfill were tested using the BSI 1377 (1990) standard. The results show that the soils have average acceptable values of 0.75% gravel, 32% sand, 48% clay and 19% silt in a compactable sandyclay soil. The result of the Atterberg limits tests showed that the soils are absolutely inorganic clay of low plasticity with average clay activity value of 0.39 which is suggesting non-reactive kaolinitic clay. The dry density of the soils are 1.80Mg/m3 and 2.1Mg/m3 when compacted at standard and modified Proctor energies
respectively while the coefficient of permeability of the soils are in the order of 1x10-9m/s and 1x10-11m/s respectively. These results compared reasonably with recommendations of several researchers. Thus, the soils satisfied the requirements for use as mineral seals in sanitary landfills. The higher energy of compaction (Modified Proctor) offered lower values of coefficient of permeability and thus recommended.