Track: Environmental Engineering

Abstract

In has long been established that the escape and consequent permeation of landfill leachate through a barrier medium is one of the contributing factors to environmental contamination, especially where vital regions with consequential impacts are concerned as in the case of soil, surface, subsurface and groundwater pollution. Although the contamination process of environmental resources from leachate permeation may be slow, it poses a significant threat to human and environmental health in the long run. These challenges paved way for the study to evaluate via laboratory tests the permeation rates of a landfill mineral lining system as compacted clay liner (CCL) overlain an unsaturated/ vadose and saturated zone of known thicknesses respectively. The laboratory permeation tests were conducted to simulate the moisture flow regime and steady/ quasi steady-state permeation rates for typical conditions of a landfill. The results of the tests revealed the hydraulic conductivity of the fine textured vadose zone to be 1-2 magnitude in order lesser than the saturated zone hydraulic conductivity. Nonetheless, the hydraulic conductivity of the mineral barrier and the permeation rate to underlying groundwater was found to dependent on the nature of the zone as the last line of defense to contaminant permeation in the event of leachate breakthrough. Thickness values of up to 225 mm for the fine textured zones were reached which appeared to be functional parts of the tested landfill mineral liner. Consequently, the vadose zone was found to behave better than the saturated zone in the permeability of the overall lining system as such, upshots of the tests showed permeability coefficient of the CCL of 24 mm natural clay mineral liner to be the key regulator of the steady/ quasi steady-state permeation rates in the overall system lining setup.