Limiting local tensions in landfill geomembranes

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Around 30 million tonnes of solid waste is generated each year in Canada (StatsCan 2005). Despite tangible results from efforts to reduce, reuse and recycle waste, Canadians will continue to require landfills for the safe disposal of municipal and industrial solid waste for the foreseeable future. Barrier systems comprised of a geomembrane (a thin plastic sheet) overlying low permeability clay are used to line the bottom of landfills. The purpose of the barrier system is to prevent groundwater contamination by minimizing the escape of toxic chemicals (like heavy metals and hydrocarbons) into the surrounding environment. A long-lasting geomembrane is key to ensuring adequate long-term environmental protection. The physical response of the geomembrane when buried beneath large amounts of waste directly impacts how long it will last, especially the local tensions that can develop in the geomembrane from overlying gravel particles. Physical experiments will be devised and conducted, and numerical analyses will be developed and applied to prevent geomembrane rupture from local tensions in landfill geomembranes. As local tensions depend on the plastic membrane, the surrounding soil, the amount of waste, temperature and time, the proposed studies combine necessary elements from geotechnical engineering, geosynthetics engineering and engineering mechanics. This research builds on the applicant's strong track record of solving problems involving buried polymer structures for use in environmental applications. Four Doctoral and five Masters students will receive advanced training over five years. As premature failure of landfill barrier systems may result in substantial long-term social, environmental and possible health impacts as a result of groundwater contamination, the proposed research will improve the long-term physical performance of geomembrane liners, and will benefit Canadians with landfills that provide greater long-term environmental protection.