Grant: Discovery Grants Program - Individual

Municipal solid waste (MSW) landfill leachate and sewage water typically contain per- and polyfluoroalkyl substances [PFAS]. PFAS have significant health effects (e.g., cancer). They are "forever chemicals" that bioaccumulate in the food chain, ultimately reaching the human body. PFAS must be contained for many decades to many centuries. Ontario requires plastic liners (geomembranes) for MSW landfills to last 150 to 350 years for smaller and larger landfills, respectively. However, there are no generally accepted means of selecting liners that will meet these or the less stringent requirements for sewage and mining lagoons. Thus, there are failures. In 2021, I investigated 5 liner failures, including a 3-year old mining lagoon liner that discharged 11 million litres of contaminated water and another 15-year old liner that discharged 800 million litres of contaminated fluid. This research program will address the root causes of liner failures by developing: a fundamental understanding of the factors affecting the efficacy of liner systems, a method of reliably estimating their service life (how long they will effectively contain fluids), design guidelines for future facilities, and a means of assessing when a failure is likely for existing facilities so action can be taken to prevent contamination. The research funded by this grant will establish the efficacy and service life of the three main components of a liner system for containing PFAS. This will require considerations of both the applications and the materials, as illustrated below. Relatively new sewage lagoons in northern communities leak excessively because of liner failures due to the liners' inability to tolerate the effects of climate change, such as thawing permafrost. This research will evaluate current and alternative liner systems and develop guidelines for the selection of appropriate liners. Multicomponent geosynthetic clay liners combine both a plastic liner and a layer of clay in a single product that can minimize leakage to a negligible level for the (unknown) service life of the plastic components of the liner. This research will provide the first study of their service life. If the service life is adequate, they represent cost-effective liners for lagoons in remote communities, and part of the liner system for many mining lagoons and MSW landfills. The research will use unique facilities, including a full-scale liner test site and lab equipment that will enable the testing of the entire liner system under simulated field conditions. The research will reduce water contamination, and benefit Canadian design consultants, regulators, manufacturers, facility owners/operators, First Nations, and the general public who will all be able to place greater reliance on these liner systems and enhance Canada's international competitiveness and reputation for environmentally sustainable development. The research will train 7 PhD, 6 MASc and 5 undergraduate students.