Not a lot of people care to think about what goes on at the bottom of a landfill, 25 to 50 metres down under all that garbage. But Dr. Kerry Rowe, of Queen’s University, thinks about it a lot. In fact, he even builds simulators to recreate that dank, soupy environment.

Dr. Rowe and his team are investigating the effectiveness of geosynthetic liners for containing contamination in landfill sites. The term “geosynthetic” refers to the use of a range of synthetic materials—usually some form of heavy plastic sheeting or fabric, sometimes combined with clay—to solve problems in soil engineering.

These kinds of liners have been incorporated in landfills for several decades (See Layers of Protection on the back), and the approach seems to be working well—so far. “The big question,” explains Dr. Rowe, “is how long they’re going to continue to perform. Landfills typically have a service life of many, many decades to hundreds of years.”

To find some answers, his team has built about 50 cylindrical simulators, with the help of an investment from the Ontario Innovation Trust. Each canister is lined on the bottom with a typical geosynthetic liner system. Liquid is injected to simulate the soupy “leachate” that accumulates at the bottom of a landfill, and adjustable bladders at the top apply pressure to reproduce the effect of varying depths of trash. Researchers can also control temperature to accelerate wear. By running a simulator at 85°C, for example, they can subject the liner to the equivalent of hundreds of years of stress in three years.

Each canister is set at its own combination of temperature and pressure to reproduce a variety of landfill scenarios. In some, the liner has also been wrinkled or otherwise deformed to test the effect this added factor has on performance. While scientists can monitor some effects in real time, the most valuable data emerges when the simulators are taken apart at the end of their runs.

The research is important for obvious environmental reasons. But there’s also an economic factor. “An Ontario company is one of only two producers of geosynthetic clay liners in North America,” explains Dr. Rowe. “They already sell all over North and South America. If we can demonstrate the particular suitability of these kinds of liners, that helps them market their product.”