Geoenvironmental Assessment of Two Tropical Clayey Soils for use as Engineered Liner Materials

Despite the global focus on waste reduction, re-use and recycling, the use of engineered landfills with either single or composite lining systems is, and will continue to be a major waste disposal method. The use of composite lining systems in landfills to effectively minimize the discharge of contaminants to groundwater is not common in most tropical, developing countries. In addition, there is also a lack of data on the performance of tropical clayey soils as liners. Adopting liner technology developed in temperate regions for application in the tropics may not be practical and cost-effective, as there are significant differences in geological, environmental and material properties in the two regions. In order to develop or reliably adopt a practical and cost-effective liner technology for tropical environments, geoenvironmental assessment of tropical soils during their interactions with the intended leachate must be undertaken. A study was undertaken to determine the suitability of two clayey soils from Ghana (West Africa) as engineered landfill liner materials. The hydraulic conductivity, before and after permeation with municipal solid waste (MSW) landfill leachate, was evaluated in a constant-flow fixed wall permeameter. The impact of the permeant on the hydraulic conductivity, mineralogy, chemical composition and some geotechnical properties of the clayey soils are presented. The results of the study suggest that the tropical soils may be used effectively as liners to minimize the discharge of contaminants into groundwater.