An experiential perspective of leachate seepage through defected geomembrane of geo-composite barrier

Abstract: Laboratory tests using a small-scale model device were carried out on leachate seepage in geo-composite barriers due to circular geomembrane defects. Various pressures simulating actual landfill waste loads were applied to the barrier systems. Seepage rate, anion migration and the attenuation tendency of a natural mineral layer were investigated. Seepage through the geo-composite barrier-attenuation strata (AS) system was determined under waste loads of up to 150 kPa impacting the defected geomembrane liner. The findings revealed appreciable reduction in seepage rate with increased pressure on the system. The reduction is ascribed to the reduced barrier transmissivity, θ and compressed soil layer. Data for seepage rates were compared with predicted values from Forchheimer’s (1930) and Giroud’s et al (1986) equations. The comparisons displayed inapplicability to this study and to real practice, if conditions of perfect contact at the geomembrane/soil interface are assumed. Nonetheless, Giraud’s (1997) equation for good contact condition gave reasonable prediction of seepage rate through geo-composite liners with defected geomembrane