Salting the Earth

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Salting the Earth

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Toronto uses over 135,000 tonnes of road salt each year. Photo by BruceK from the Torontoist Flickr Pool.


After an extended fall, Toronto is finally in the grips of the cold season. And like every winter before, the city’s streets are beginning to look like chalk boards as they become blanketed with road salt. Can anything be done to prevent those dreaded salt stains at the bottom of our pants, and protect our dogs from months of paw pain? Or are we doomed to live in a city saltier than a bag of Miss Vicky’s?


The drawbacks of salt have been well documented. In 2001, Environment Canada released a statement that said road salt was entering the environment via groundwater in large amounts and was posing a risk to plants, animals, soil, drinking water, and lake and stream ecosystems. Not to mention the number it does on our infrastructure each year, causing more potholes and cracks in the sidewalk every winter season. Environment Canada even concluded it should be labelled a toxic substance.
The Transportation Services Division of Works and Emergency Services—the body that manages road salt storage and distribution—states in its Salt Management Plan [PDF] that salt is the most effective de-icing agent for keeping Toronto’s drivers and pedestrians safe, despite the environmental damage it can do. Since there are no mandatory regulations for managing road salt storage or distribution, Transportation Services is under no obligation to cut down.
So, for now, the city uses 135,000 tonnes of the stuff each year, despite cries from the community to reduce our dependency on sodium chloride. Riversides, a non-profit organization dedicated to preventing water pollution, began its municipal Low Salt Diet campaign in 2000 to promote the reduction of road salts, the elimination of unregulated snow disposal, and use of road salt alternatives. They are particularly concerned with Ontario Regulation 339, which exempts road authorities’ use of materials that are classified as environmentally harmful under the provincial Environmental Protection Act. They have since disbanded the official campaign, but continue to create awareness about road salt.

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Photo by Michael Chrisman/Torontoist.


Riversides suggests many possible alternatives, and calcium magnesium acetate is the most explored substitute. It doesn’t de-ice on its own, but if it’s applied ahead of a snowstorm, it breaks the bond between snow particles and the road surface, making plowing much easier. It also doesn’t contain any chlorides, and it is biodegradable.
Liquid potassium acetate is the most environmentally friendly de-icer, as it’s chloride-free, biodegradable, non-corrosive, and has a low toxicity. It’s best used in areas where corrosion or environmental damage is of greater concern. Sodium acetate, currently used on many airport runways, is also much less damaging.
Even sand, kitty litter, gravel, and ash can be used for traction, but they don’t actually melt ice.
Why not abandon salt in favour of these more environmentally favourable alternatives? It comes down to cost: non-saline alternatives can be up to ten times as expensive. Councillor Joe Mihevc (Ward 21, St. Paul’s), who has been tweeting about road salt, told us that “this is where I think we need to do some exploring, do some cost benefit analysis.” When it comes to alternatives, “Maybe at first you just do the sidewalks, and then you slowly build it into the budget. That way we don’t get wacked all at once.”
Mihevc points to a method the city is already using as a good start—a liquid brine. Although it doesn’t eliminate the use of salt altogether, combining salt with water can increase its efficiency and reduce the need for such copious amounts. Salt doesn’t work without water, so that’s why you see all those little chunks bouncing to the side of the road where they go wasted. A brine would help prevent that wastefulness, because the substance would stick to the road, and it would make salt work better in sub-zero temperatures when moisture is lacking. “We do this on the highways and some of the roads,” Mihevic says, “and it uses less than half the salt we would have otherwise. That’s what we should be doing everywhere.”
So for now, it looks like the brine is our best solution. When it comes to spending tax dollars, the city has higher priorities, and unless the community really mobilizes against salt, don’t expect to see kitty litter on your streets any time soon.
Thanks to reader Mark Jull for getting us thinking about salt.

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