A new study by a McGill University professor shows Montreal is leaking greenhouse gases from some long-buried sites. Landfills — or garbage dumps — were covered up decades ago and, in some cases, turned into parks on the island of Montreal. One such place is Frederic Back Park in the city’s east end, where some 40 million metric tonnes of garbage continue to rot in a buried landfill. The landfill may be out of sight, but it continues to churn out methane, a byproduct of decomposing waste and a gas largely driving climate change. Frederic Back Park uses technology to capture the methane emissions, and the McGill researcher says more sites should do the same. “In an ideal world, we would have really great technology to capture all of this gas and burn it and use it for energy,” McGill assistant professor Peter Douglas told CTV News. “Or we do a really great job composting with much less organic waste in the landfills in the first place, so that material is being used to grow food instead of just sitting in a pit accumulating gas.” At Frederic Back Park, more than 200 underground capture wells, connected by a 17-kilometre network, pump the biogas to a power plant where it is used to produce electricity. The McGill study indicates there are some 3,000 sites on the island that are leaking methane. One of the worst offenders may surprise some: it’s the annual winter city snow dump used by snow-clearing crews.