Potential of Lateritic Soils as a Liner in Landfill: A Case Study of a Dumpsite in Ado-Ekiti, Southwestern Nigeria

Abstract

The permeability characteristics of the lateritic soil from Ilokun dumpsite were studied with a view of investigating its suitability or otherwise as liners in sanitary landfills. The soil samples were collected from trial pits at different depths within the lateritic soil zone. The samples were subjected to specific gravity test, grain size distribution analysis, consistency limits, compaction tests and permeability test. All the soil samples are well graded. The study also showed that the plasticity of the soils ranges from medium to low plasticity and hence low compressibility. The Maximum Dry Density (MDD) values for all the studied soil samples range from1.72t/m3 to 2.02t/m3 for Standard Proctol and the Maximum Dry Density (MDD) values of the studied soil range from1.78t/m3 to 2.08t/m3 for Modified Proctol while the Optimum Moisture Content (OMC) values of the studied soil range from 9.0% to 14.0% for Standard Proctol and the Optimum Moisture Content (OMC) values of the soil range from 7.0% to 13.0% for Modified Proctol. It was revealed that the higher dry density values were obtained when the soil samples were compacted with higher energy of compaction. The coefficient of permeability obtained for the samples range from 1.5 x 10-3mm/s to 2.5 x 10-2mm/s and this is considerably higher than the maximum value of 10-6 mm/s recommended for the soil that should be useful as a liner in landfills. It is therefore recommended that in-situ compaction and lining be done if the soils at the location will be used as liners in landfill. This will hinder the migration of liquid phase of the wastes.