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Water Today Title April 14, 2021

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Advisory of the Day



This story is brought to you in part by Dagua

Canadian winters are increasingly unpredictable. Roads need to be cleared from ice and snow to be safe for driving. The use of abrasives and ice melters is routine business. Let's take a look at the common practices in the province of Québec.

Icy roads are a major issue for drivers. Even with the best winter tires, a patch of black ice can mean accidents, injuries or death. The use of abrasives like sand, gravel and stones are good when used on top of the ice, but as soon as snow, rain or ice storms hit, it's time for more. The solution is to get rid of the ice. Two options are then available: mechanical removal, which is time consuming and very hard on machinery, more prone to breakage and costly repairs; or, simply melt the ice away using de-icing products.

With many roads to maintain and sub contractors usually doing the work, the Ministère des Transports du Québec issues a publication with all the rules and guidelines to follow in order to do business with the provincial body. The last version of the Cahier des Charges et Devis Généraux - Déneigement et Déglaçage was published in 2014. It mentions Calcium Chloride as the authorized de-icing product along with finely crushed rock, gravel, and sand the size of which must be no larger than 1.75 mm to 8-10 mm.

Calcium Chloride is basically table salt, the kind you put on your food. Calcium chloride is composed of 40% Calcium and 60% chlorine. It is a refined salt. Contrary to popular belief, it is not the same as sodium found in organic nutrients such as vegetables as it has been chemically modified. Technically, Calcium Chloride gets into the soil on the side of the road and surrounding snow disposal sites in the spring season.

We spoke to Mr. Marc St-Arnaud, Associate Professor of Microbial Soil Ecology. We asked him if Calcium Chloride accumulation once the snow is melted could have an impact on microbial levels in the soil: "Theoretically, Calcium Chloride is a stressing agent on the microbial level. To sum it up simply, the weakest taxons (conceptual summary of similar biologic entities) would tend to move away from the stressing agent and the stronger taxons would take their place and could cause some sort of unbalance. It depends on a multitude of factors of which I can't comment on further as this is not my specific field of research."

We found extensive research on the matter on a Health Canada webpage which was archived in 2013. The research concludes somewhat vaguely:

Based on the available data, it is considered that road salts that contain inorganic chloride salts with or without ferrocyanide salts are entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity."

The webpage contains a chart entitled 'Total loading of sodium chloride road salt, winter 1997-98 (from Morin and Perchanok, 2000)', the total amount for the province of Quebec is a staggering 1 544 512 tons across its territory, which is still second to Ontario's with 1 845 329 tons.

Municipalities are among the biggest users of de-icing products. The biggest city of the province is undoubtedly Montreal. Cities have to remove the snow fallen and dispose of it somehow. The snow to be disposed of is filled with Calcium Chloride residues and subsequently these residues are brought along for the ride. For a long time until recently, the city of Montreal disposed some of the snow directly into the St-Lawrence River near the Jacques-Cartier Bridge. As of now, Montreal disposes of the snow on the surface or thru the sewage system as shown on this mapfound on the city's website.

No scientific data clearly stating immediate or long-term damage due to Calcium Chloride use on the province's roads. Unless the public and environmental organizations put pressure for a full assessment, nothing points to any changes in the near future.

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