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ROAD SALT: WHAT IMPACT CAN IT HAVE ON OUR WATER SYSTEMS?
FluksAqua Community, Water and wastewater community, Tagged
drinking water quality,
As the temperatures rise and spring arrives, winter may seem far away but its long-term effects are lingering. North Americans may have adapted to winter by bundling up as the temperature drops however, when it comes to roadways and parking lots, they expect winter to be kept at bay.
Spreading large amounts of road salt in the area has long-term environmental impacts including on the water supply. According to a recent study of 371 lakes in eastern North America by the Global Lake Ecological Observatory Network, melting snow from roads and parking lots is a threat to thousands of lakes.
CULPRITS: HOMEOWNERS AND PRIVATE BUSINESSES
Whether road salt is applied to roads, sidewalks or parking lots, it becomes part of the environment. It will either end up in the soil or runoff to nearby streams, rivers or lakes. It is estimated that 23 million tonnes of salt based de-icer is applied to North American roads every year.
While it would be easy to point the blame at municipalities, most of them are actively working to reduce their road salt use. In Canada, there has been a voluntary code of best practices in place since 2001 to help municipalities and cities to cut down their use and approximately three-quarters have adopted it. And it is working. For example, Toronto has reduced its road salt use by 25 per cent.
In fact, the biggest offenders are usually homeowners and private businesses. Research has found that many private businesses and shopping malls contribute to the problem by applying salt and chemical de-icers to get rid of snow instead of plowing it. It may mean customers can easily find a parking spot but it is having negative impacts on our water supply.
The problem is salt cannot be easily removed from water. While it will be some time before salt overwhelms our water supply, techniques such as reverse osmosis and desalination require a large investment to create and operate and still have a negative environmental impact. So as the salt level rises in freshwater sources, the drinking water supply may begin to taste or smell differently. It can even become an issue for individuals on a restricted low-sodium diet.
THE IMPACT OF ROAD SALT ON WATER SYSTEM OPERATIONS
Salt can become toxic to the water distribution network. Water operators face challenges with corrosion caused by salt in service connection pipes and plumbing fixtures that may reduce the life of the infrastructure and change the chemistry of the water. These changes mean operators have to monitor the water supply to ensure they continue to comply with the lead and copper rule. Ultimately, water operators need to ensure they meet the appropriate safe drinking water regulations and have salt levels at below 250 mg/L.
But it is more than just a drinking water issue. Increased chloride levels affect the entire water ecosystem from the fish to the invertebrates they eat to tiny plankton. It also makes lakes more vulnerable to invasive species and harmful forms of algae. In extreme cases, excess salt can prevent lakes from mixing, causing low oxygen conditions that smother aquatic life and reduce water quality. Researchers say it takes a lot of salt to kill a lake but only a small amount to make it sick.
There is a pressing need to solve the road salt problem sooner rather than later. The study of 371 North American lakes concluded that if current practices don’t change, many lakes in eastern North America will surpass the scientifically recommended safe salt level within 50 years. Water operators, conservationists, municipalities, states and provinces are using public awareness campaigns to try and reduce the amount of salt spread on the road. For example, the Minnesota Department of Transportation has been reducing their road salt with new technology that helps determine the right amount of salt to apply and communicating best practices with local communities and snow clearing businesses.
EDUCATING THE PUBLIC
More people need to understand the negative implications of using road salt and start choosing alternatives. The most efficient and effective way to remove snow is to physically remove it by shoveling, plowing or snow blowing. If you keep up with snow clearing even during a storm, there is less chance for the snow to pack or get too deep. The sun can also be of assistance even in the winter. Dark pavement exposed to sunlight will absorb heat and help with the snow. Ice breakers can help remove snow that is packed to the pavement. The flat metal blade will loosen and then scrape the snow away.
Road salt is usually sodium chloride but could also include calcium chloride, potassium chloride and magnesium chloride. For a road salt alternative that is better for the environment, calcium magnesium acetate (CMA) is a non-chloride based product. Acetate quickly breaks down in soils and calcium and magnesium are less harmful to the environment than sodium and chloride. CMA products are more expensive than traditional road salt and aren’t quite as effective at extremely low temperatures, but your local water supply will benefit.
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