Peace and Environment News* February 2002
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Peace and Environment News * February 2002 |
by Sharon Boddy
In August 2000 Environment Canada completed a five-year study of the effects of road salt on the environment. They concluded that road salt (sodium chloride, calcium chloride, potassium chloride, magnesium chloride, and ferrocyanide salts) is toxic to the environment, particularly in large concentrations, but does not harm human health.
Every year, almost 5,000 kilotonnes of road salt are used on Canadian roads in winter and as a dust suppressor in summer. Salt can leach into lakes, streams, and groundwater through runoff and through inadequate storage facilities, posing a lethal threat to some aquatic species.
Some municipalities, however, are concerned that the public may confuse "toxic to the environment" with "toxic to human health." Robert Chénier, Section Head of Environment Canada's Chemical Evaluation, reports that, of the 30-odd submissions Environment Canada received from municipalities, many cited public confusion as an issue. "I sympathize with those points," he says, "but the public knows what road salt is, and I don't think municipalities should be unduly concerned."
One alternative to road salt is to use Road Weather Information Systems (RWIS). RWIS use a combination of roadside weather stations and sensors embedded in the roads to forecast weather conditions so that municipalities can apply a liquid anti-icer to roads before ice and snow bond to the pavement.
Unlike road salt, liquid anti-icers contain only magnesium and calcium chloride. Magnesium and calcium, minerals essential for plant growth, are found naturally in soil and water and are tolerated in high levels by most plants. The Insurance Corporation of British Columbia has found that magnesium chloride is 70 percent less corrosive than road salt, and its use in Kamloops has prevented about 300 collisions over a three-year period.
Ten RWIS sites have been in operation in Ottawa since 1996. Mohamed Alkoka, Operations Engineer with the Transportation and Public Works Department, reports that, although it is difficult to measure exactly how much salt usage has been reduced, "We've maintained salt consumption and increased coverage on the roads."
Since Ottawa receives an average of 230 cm of snow every winter, Alkoka believes that the proactive approach is the way to go. "The RWIS allows us do more precise forecasting and pre-treat roads before not after." Alkoka also participated in developing the Transportation Association of Canada's Road Salt Usage Guide, a code of practices that address the design of road maintenance yards, drainage and storm water management, good housekeeping practices, pavement, road and bridge design, vegetation management and winter maintenance equipment.
Road salt can be costly to municipalities, in lost salt due to inadequate storage facilities, in its corrosive effects on vehicles and equipment, and in loss of vegetation. In the early 1970's in New Hampshire, for example, 14,000 trees were lost along 3,700 miles of salt-treated highways, and in the whole of the United States chloride salt damage to vehicles, roadways and infrastructures is estimated at over $15 billion annually.
This article originally appeared, in part, in the May-June issue of Forum Magazine, a publication of the Federation of Canadian Municipalities.
Converted February 17, 2002 - Lg
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