When winter storms hit and snow covers the roadways, runways and sidewalks, the salt comes out. While sodium chloride works wonders for de-icing, concern is growing over its harmful environmental effects. Once the job is done road salt has to go somewhere and most of it ends up in our waterways. A 2009 University of Minnesota study found that about 70 percent of the 350,000 tons of road salt used annually in the Minneapolis metro area is retained in the watershed of area lakes, rivers, wells and tributaries, which could affect drinking water and aquatic life.
That's why this year, many public works officials in Minnesota are changing their de-icing formulas. The trick is to make the salt stick to roads better so less salt can be used overall, maintaining the same level of safety. Pre-wetting the salt with brine before applying it to the road has helped many crews go from using 500 pounds of salt per mile to 200 pounds per mile. One city, Prior Lake, created a road salt "supermix" of brine, magnesium chloride and a sugar beet byproduct, which has reduced salt use there by about 60 percent. Even food-grade molasses can help salt stick to roads--but it doesn't work so well in frigid temperatures!
Airports are beginning to look for eco-friendly salt alternatives, too. Frankfurt's airport in Germany uses a biodegradable antacid to battle snow and ice, which is non-toxic and doesn't affect groundwater. It's good to see more cities taking the initiative to find alternatives that are safe for travel and safe for drinking water.
Photo by bradjward via flickr under a Creative Commons license.
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