Effect of time and temperature on critical geosystems

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Landfill barrier systems typically involve a leachate collection system (to collect contaminated water) and a composite liner. The composite liner often includes a 1.5-2.5mm thick polymer (geomembrane, GM) liner over a geosynthetic clay liner (GCL) which includes a thin layer of bentonite clay which swells on contact with water and substantially reduces leakage through holes in the geomembrane. These geo-systems are typically expected to function for many decades to centuries. However, unless we change our designs and/or operations, some of these systems are unlikely to have the desired long-term performance (for example, a leachate collection system can block-up due to biologically induced clogging). This research will result in a unique calibrated computer model that can be used in design of leachate collection systems that will provide the required long-term performance. Following modelling, lab and field studies to discover and explain the underlying mechanisms, a simple design procedure will be developed for use by engineers. My research into GMs will provide the first clear quantification of the effect of GM thickness on their long-term performance while research relating to different GM formulations is expected to result in more sophisticated specification requirements than are currently required. It will also provide the first ever projections of long-term GM performance under realistic exposure conditions for both single and double liner systems. It has recently been recognised that some modes of landfill operations result in liner temperatures that may reduce their life to a few decades or even less. Techniques for controlling liner temperatures for these situations will be investigated. Finally, the effectiveness of modern barriers for controlling the escape of perfluorinated chemicals will be investigated. This research will benefit Canadian and international design consultants and regulators, landfill operators and the public who will all be able to place greater reliance on these geo-systems. The research will provide training to 9 PhD students.