Sowing Our Roads with Salt Is No Way to Grow Stronger Towns

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Even though road salt decreases the life expectancy of our infrastructure, in the Northern U.S. and Canada, it’s become a necessity to making our roads safe for driving in snowy winters. Typically, we cover our roads with halite, or rock salt (the same form of salt we sometimes use for french fries) once it’s been through a lengthy purification process. 

Salt works by lowering the freezing point of water through a process called freezing point depression. Water needs to be at a temperature of 32 degrees Fahrenheit (0 degrees Celsius) to begin forming into ice. Essentially, once salt is added into the mix, water has to get a lot colder than it normally would to freeze. That’s how we get the ice-melting-effect when we sprinkle salt on our front porches. 

Of course, inexpensive rock salt isn’t the perfect solution to de-icing. When temperatures drop below 20 degrees Fahrenheit, it can be too cold for sodium chloride to be effective on its own. That’s when you may see local public works and transportation departments adding other chemicals (salts) such as magnesium chloride or calcium chloride to their salt (sodium chloride) mixes. 

Not only does sodium chloride contribute to the erosion of pavement and metal, once it washes away from the road, it leaches into the ground and can pollute our freshwater systems, causing a rise in sodium levels. And as of right now, we have no way to remove it. In 2018, a study of wells in Dutchess County, New York, found that the sodium concentration was much higher than the federal and state recommendations. They discovered levels as high as 860 milligrams per liter in some wells, while the general recommendation sits at 270 milligrams per liter. 

Joseph Stromberg from the Smithsonian Magazine wrote, “As more and more of the U.S. becomes urbanized and suburbanized, and as a greater number of roads crisscross the landscape, the mounting piles of salt we dump on them may be getting to be a bigger problem than ever.” 

Canada declared road salts as an environmental toxin in 2004, and they placed new guidelines on its use. Many local U.S. governments have searched for ways to at least reduce the use of road salts. Finding an alternative that eliminates the use of salt entirely is not so simple, though, as many of these alternatives have higher upfront costs. Other potential de-icing options that are at the same or lower price point of salt tend to not be as effective in breaking down icy roads. 

Removing salt from our roads entirely may seem a daunting feat while we rely on cars for transportation, but perhaps we can reduce its use. Organizations and some local governments are focusing on spreading the right amount of salt for different conditions. 

The Minnesota Pollution Control Agency, for instance, offers “Smart Salting” training to individuals and organizations. Their goal is to “provide the latest technologies, best practices and tools, and available resources to assist your organization to be effective and efficient in managing snow and ice.”

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