Salt of the Earth
Keeping roads safe doesn’t have to mean poisoning wildlife.
By Nancy Payne
When snow and freezing rain descend, Canadians’ weapon of choice is rock salt. Trucks spray it on the roads, businesses toss it on the sidewalk, and homeowners sprinkle it on their driveways. You’d never know that eight years ago, Environment Canada declared salt an environmental toxin.
Meltwater carries salt contamination into wells, streams, wetlands and small lakes, threatening fish and frogs. “If you look at water quality, you’d find sodium chloride levels are higher today than they were 50 years ago,” says Bill Freedman, a professor of biology at Halifax’s Dalhousie University. Ontario’s environmental commissioner estimates that 30 to 45 per cent of all chlorides present in the Great Lakes are a direct result of salt on our highways and streets.
Plants as far as 50 metres from a road can succumb to the salty spray kicked up by cars and trucks. More salt-tolerant species move in, changing the ecosystem and often allowing invasive plants to take over.
Larger animals, especially deer, moose and other mammals desperate for sodium, are attracted to roads, where they are too often hit and killed as they lick up salt. Birds, thinking the grains are seeds, swoop down and face a similar fate. It doesn’t make sense, says Freedman. “The last thing you want to do is use something that will attract more animals to roadways.”
When Environment Canada sounded the alarm, it followed up with a code of practice in 2001, urging municipalities to reduce their use of salt on winter roads without compromising drivers’ safety. Emerging options cost two to 20 times more than salt, and each tends to have its own environmental drawbacks. Many only work at -10 C or higher.Until a reasonably priced alternative appears, municipalities across the country are working hard to cut their use of road salt. Ken Lauppé is manager of road operations for the city of Brampton, west of Toronto. Staff there determined how much salt was needed for every bit of municipal road, so that now “contractors on every route get the designated amount of salt, and not a pinch more,” says Lauppé. Electronic controls regulate the flow of salt. Sometimes it’s as basic as plowing more, instead of dropping more salt.
Spraying a salty liquid brine onto roads when a storm is expected prevents snow and ice from bonding to the pavement, says Lauppé, who also sits on the Ontario Road Salt Management Group. Brine is also used to wet the salt being spread so it stays on the road. “When salt hits a dry surface, it bounces all over the place like marbles. Wet it, and it stays in place.” The technique has helped Brampton reduce its salt use by 30 per cent.
Other municipalities are installing sensors that tell crews when and where to apply salt based on weather conditions. The city of Vaughn, north of Toronto, is experimenting with a derivative of beet juice.
But what about your driveway and front walk? Well, as with so many household environmental choices, the first line of defence is elbow grease — shovel early, shovel often. Of course, that doesn’t help when there’s freezing rain, or after a thaw-freeze cycle.
Sand will help keep you from slipping, and on a sunny day, can melt down into the ice and snow, helping to break it up. Too much of it can wash into waterways or blow around come spring, contributing to air pollution, so use it judiciously.
Crushed rock or gravel and wood shavings will also help you get a grip. Sweep up the shavings in the warmer weather to use as mulch; rake the gravel into a pile and put it away for next year.
And if you must use salt, use it sensibly. Freedman finds it strange that although the federal government has declared salt toxic, “there aren’t significant instructions for the average person on its use. It should be a controlled substance, in my view.”
Do Your Part
One of the reasons municipal salt use has climbed is that we’ve come to expect bare roads to drive on, no matter what the weather, something Brampton road operations manager Ken Lauppé has observed in his 20 years on the job. “Over the last few years, I’ve noticed heightened expectations of our local roads. Commuters see the major arterial roads are bare and then they turn onto their local road and expect it to be the same.”
Be realistic about the conditions you’re driving in. And for safety’s sake, invest in snow tires.
The Verdict
Best choice for household use: wood shavings or gravel
Okay choice: sand
Worst choice: rock salt
Look after your own front yard, and lobby your municipality to cut down on its use of salt and investigate more environmentally sound options such as calcium magnesium acetate and magnesium chloride.