Circular defect as potential pathway in polyethylene forming part of a geo-composite lining system

Abstract: Geo-composite barriers under leachate leakage through circular defects in a geomembrane were tested in a small-scale laboratory model. A soil barrier-24 mm thick, polyethylene plastic-2mm thick with centered 5 mm hole simulated the circular defected geomembrane and a 225 mm thick buffering profile (BP) completed the experimental setup. A Modular Consolidometer-Percolation Column Hybrid model of 160 mm diameter is coupled to a hydraulic pressure frame capable of applying up to 1000 kPa pressure to the liner. Leakages through barrier-BP system were evaluated for tests under pressure of up to 150 kPa. Measured leakage rates for good geomembrane/soil interface contact conditions were found to be valid whereas that of a perfect contact condition was unachievable in this study. However, outcomes show notable reduction in leakage rates with increased pressure, p, on the geomembrane. This is plausibly due to reduced barrier system transmissivity, θ, and densification of the barrier. Concentrations of dreaded Organic matter in the BP after percolation tests confirmed leakage through the defected polyethylene-soil liner and showed poor buffering abilities of three natural soils investigated in this study to migrating organics