MOISTURE FLOW IN MINERAL LANDFILL LINERS UNDER TEMPERATURE-GRADIENTS

In order to assess the risk of desiccation and cracking of the mineral bottom liner (without plastic liner) of a seven years old warm landfi ll, water contents were measured and soil hydraulic parameters determi ned in the lab. No cracks were visible, and a desiccation could not be proven due to the high spatial heterogeneity of the liner. Studies wi th a newly developed numerical model of coupled moisture and heat tran sport show that mineral liners might only crack if a plastic liner or very dry waste obstruct the temperature induced vapor transport from t he waste to the mineral liner. Whether desiccation occurs under these conditions depends on the distance to groundwater and on the unsaturat ed hydraulic conductivity functions of the mineral liner and the subsu rface. Simulations with unsaturated hydraulic conductivity functions t hat have been determined by different methods indicate that a new stan dard method to determine the unsaturated hydraulic conductivity of den se clayey substrates is necessary.