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Water Today Title October 23, 2020

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Update 2020/3/17
Geosynthetics



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WORKING WITH NATURE IN LANDFILL MANAGEMENT: A QUEEN’S RESEARCH PROJECT




By Suzanne Forcese

Garbage. The hundreds of millions of tonnes of it produced annually including dangerous waste coming from energy generation and mining of resources eventually finds its way to a landfill site where it could contaminate surface and ground water. Preventing an environmental disaster requires study of topographical and hydrogeological features of a surrounding landscape and the interactions that can occur on site as we face climate change concerns. We only have to look at legacy sites to remind us that waste management is a complex issue that requires innovative solutions that will stand the test of time.

It was 1978 when a young Australian geotechnical engineer landed at Western University in London, Ontario. That same year, Love Canal, located near Niagara Falls in upstate New York, became a shocking example of ground water pollution. The small working-class enclave was capturing world attention. Hundreds of houses and a school were sitting on 21,000 tonnes of buried toxic industrial waste chemicals, including at least 12 that are known carcinogens. The toxic soup had seeped into groundwater and to the surface, oozing into yards and basements. As the news of the town’s evacuation and relocation of 900 families was unfolding, R. Kerry Rowe thought to himself, “Surely we can do better than that.”

WaterToday had the pleasure of speaking with Queen’s University Distinguished Professor R. Kerry Rowe, FREng; FRS; Canada Research Chair in Geotechnical and Geoenvironmental Engineering. Research and consulting topics in Dr. Rowe’s area of expertise include containment of contaminated sites and infrastructure systems for landfill management.

Dr. Rowe is also one of the pioneers of geosynthetics – a method of working in harmony with nature to protect the environment from contamination waste. The research passion that has been recognized by over 120 awards began in 1978.

The Love Canal Catastrophe changed the way governments looked at cleaning up the worst of the hazardous chemical waste sites in the U.S. It also changed the course of Rowe’s career.

“I was contacted by a colleague who was studying a landfill near Sarnia, Ontario, that had been built in much the same way as the Love Canal. The Canadian site was different though because the soil surrounding the landfill consisted of a natural clay.” As a result, the Sarnia site had not experienced the same fate as the Love Canal. “But if we think of a bathtub and we leave the water running – eventually it will overflow.”

Although the Sarnia landfill site actually had a natural lining there was no leachate collection system. The system had worked but there was still the potential for failure if that bathtub overflowed.

“In cases like this, it is a matter of trying to avoid any leachate escaping and permeating the ground water.”

Leachate is the liquid that arises partly from the degradation of organic matter and partly from rain or snow melt percolating through the waste. This was the case in Love Canal where consecutive wet winters raised the water table and caused the toxic chemicals to leach via underground swales and a sewer system that drained into nearby creeks. The need for safe ways to dispose of a wide range of wastes, including municipal, industrial, hazardous, nuclear, and mine waste must also recognize “that some measures can and will fail at some time.”

The Sarnia landfill site became Rowe's inspiration. Knowing that it had worked while other systems had failed, and also that it could still fail like that overflowing bathtub, he set out to duplicate the natural infrastructure in other areas of the world that did not have the natural protections. It has been a 40-year labor of love for which he has been awarded the Order of Canada, one of our country’s highest honours. (The motto of the Order DESIDERANTES MELIOREM PATRIUM means “They desire a better country”).

A particular line of Rowe’s research is assessing the effectiveness of plastic (geomembrane) liners and geosynthetic clay liners (a composite material incorporating clay) that limit contamination from mining operations and waste disposal facilities.

“A plastic geomembrane is essentially impermeable to leachates – as long as there are no holes.” Rowe’s solution – bentonite clay. “The same stuff that kitty litter is made of. When it is wet it swells and clumps. What we have created in our lab is two textiles with a bentonite liner in between. It is a composite that can stop up a hole. It’s much like putting your finger over a hole to stop the leak. The clay swells into and around the hole.”

“Civil engineering research is about thinking of potential risks and effects. What could go wrong and what would be the consequences of going wrong and how can we mitigate them? Part of what we’ve been doing is developing techniques that work with nature and trying to make nature they work for us instead of against us.”

In the North, for example, a freeze cover would protect the surrounding environment. However, if those freeze covers thaw there will be an issue. “With climate change, we can see it is an issue that could arise.”

Rowe admits that the research is a long process that requires patience. “Our longest running experiment has been ongoing for 25 years.” Rowe’s colleagues and students work at a 100 square metre field site. The university’s landfill field station just north of Kingston provides them with real life exposure to weather conditions that could affect the performance of the geomembranes. Rowe acknowledges that conditions vary in different areas. A mining tailings pond for example would definitely create a different set of variables.

Newer designs that Rowe is working on with his research team are looking at the longevity of systems as changes occur. “In Ontario we have a high water table, making it possible to take advantage of hydraulic containment.” The external pressure of water from outside the landfill prevents contaminants from escaping.

It is however necessary to anticipate what might happen with the pace of climate change with seasonal temperatures and water flow patterns becoming significantly different over the next 50-100 years.

“I expect I will still be involved in research over the next 10 years.” Rowe is however quick to point out that the research successes are due to the hardworking team of colleagues and students whose passion for environmental protections equals his.

Dr.Kerry Rowe
Dr. R. Kerry Rowe at Queen’s University Landfill Field Station
Photo courtesy Dr. Rowe


suzanne.f@watertoday.ca



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