Geotechnical assessment of Malaysian residual soils for utilization as clay liners in engineered landfills

Compacted natural soils are often used as liner materials in engineered landfills to minimize the environmental impacts attributed to landfills by preventing the migration of leachate and landfill gases into the environment and groundwater. Numerous researchers have assessed the suitability of typical Malaysian residual soils as clay liners in an engineered landfill. However, previous studies evaluated their suitability for liner application using just tap water as the saturating and permeating fluids, which is far from being representative of the field conditions. Hence, this study aimed at evaluating the suitability of two residual soil deposits of Kenny Hill rock formation as liner materials in engineered landfills by conducting a series of geotechnical tests using both tap water and municipal solid wastes leachate as saturating and permeating fluids. Results of the study indicated that soil A complied with all the requirements for liner utilization in terms of fines content, plasticity index, hydraulic conductivity, and unconfined compressive strength (UCS). On the other hand, soil B failed to meet the requirements in terms of fines content and UCS. When leachate was used as permeating fluid, there was a reduction in the hydraulic conductivity of both soil samples. Nonetheless, increased UCS and reduced Atterberg limit were observed for both soil samples when saturated with leachate. Based on the results, it is fair to conclude that soil A is more suitable for liner utilization relative to soil B.