by Allan Britnell
We all know that we should reduce the amount of salt in our diet. But we also need to limit the amount that gets into the environment. Unfortunately, Canadian winters lead to more than five million tonnes of rock salt being dumped on roads, sidewalks and parking lots each year. And while the salt is great at melting snow and ice, the saline slurry that results can damage or kill adjacent vegetation, or wash into nearby waterways and cause potentially devastating consequences for the wildlife there.
GO Transit may have found an alternative to salt, and not just for environmental reasons. Salt is corrosive to concrete and metal, causing extensive damage across the province every year. That’s bad news for the train and bus system operator, which needs to keep everything from parking lots to train platforms ice free, lest customers slip into the path of oncoming vehicles. GO uses about 2,000 tonnes of rock salt a year, equivalent to 200,000 10-kilogram bags. (By comparison, the Ministry of Transportation, the province’s largest user of salt, sprinkles between 500,000 and 600,000 tonnes of salt on Ontario’s highways each year.)
GO Transit estimates that corrosion due to salt shortens the lifespan of its train platforms by five to eight years. Worse still, many GO stations are located in or near environmentally sensitive sites. Clarkson Station in Mississauga, for example, straddles Sheridan Creek, just upstream from where it flows through Rattray Marsh on the way to Lake Ontario.
So, last winter, the provincial commuter agency teamed up with Credit Valley Conservation, the University of Waterloo and Environment Canada to test the effectiveness and environmental impact of a potassium chloride-based de-icer, Mountain Organic Natural Icemelter. (Whereas salt is a well-known plant killer, potassium chloride is a key ingredient in fertilizers.)
The team installed monitoring equipment at Clarkson Station to test for sodium, nutrients, metals, oil and other contaminants in storm drains leading from two isolated parking lots. The potassium product was used exclusively on one lot, while regular rock salt was used as a control on the other. Preliminary results will be released this fall, and the study will continue again this winter.