Long-term performance of geosynthetic barrier systems for groundwater protection

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Geosynthetic barrier systems are used in most landfills (taking 68% of Canadian solid waste), contaminated fluid lagoons, and many mining applications (eg. heap leach pads, tailings storage facilities; using 280,000,000 m2/yr of geomembrane) where loss of contaminated fluid to surface or ground water must be minimized. Historically, this system has often involved a single composite liner with welded panels of a 1.5mm thick (plastic) geomembrane liner over a 1 cm thick geosynthetic clay liner (to reduce leakage through holes in the geomembrane) and past research has focused on this case. It is now known that a single liner is only suitable for low risk projects and a double system with a geocomposite drain between two composite liners is routinely being used for large landfills or other higher risk applications. These systems are typically expected to limit contaminant escape (ie. have a service-life of) from many decades in some resource recovery applications, to centuries for large landfills, to millennia for some mine waste. At present, virtually nothing is known about the effect of chemical interaction or applied loads on leakage through composite liners or the service-life of double composite liner systems. This research represents a completely new area of investigation and will be the first to ever examine these issues. The research capitalizes on recent research breakthroughs and adopts a new research strategy for considering the interactions between all components of a double composite liner barrier system including the effects of aging on flow in a secondary drainage layer (geocomposite drain). It is unique, novel ">new techniques health and the environment by providing: (i) new fundamental scientific insights into the processes controlling long-term performance of single and double composite liner systems; (ii) science-based estimates of service-life; (iii) new guidelines for the design of barrier systems for landfills and mining applications, & (iv) a scientific basis for 21st Century regulations to provide environmental protection. The research will benefit Canadian design consultants, regulators, manufacturers, geosynthetics installers, facility owners/operators, First Nations, and the general public who will all be able to place greater reliance on these barrier systems and enhance Canada's international competitiveness and reputation for environmentally sustainable development. The research will educate 8 PhD, 2 MASc & 5 undergraduate students.