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.