Montana testing new deicer to save money, prevent winter accidents

Rock salt is corrosive to the unprotected undercarriages of automobiles and other iron based structures. It is also toxic to most plant life surrounding roads and highways. Consequently, magnesium chloride has been used more often in recent years because it is less toxic to plant life than rock salt and can be applied before or after winter storms. It is also said to be less corrosive to concrete steel and other iron alloys.

However, a white paper published by Peter G. Snow, FACI of Burns Concrete, Inc. states, “At the end of this report a literature review list from a worldwide search will reference a body of scientific literature and studies that indicate that salts containing magnesium are the most destructive deicing chemical commercially available.”

There are a variety of other compounds used for the purpose, but they all seem to have their own drawbacks. Departments of transportation have to weigh the impacts of the materials and methods used in the real world application to traffic safety and the impact on not only the environment, but the vehicles they use to keep our roads safe.

So the Great Falls Division of the Montana Department of Transportation has opened a brine mixing facility west of the city, said Mick Johnson, district administrator, according to an article in the Great Falls Tribune by Richard Ecke. The city is making this move only after its confirmed efficiency in Kalispell, Missoula and Helena where it has worked well in dealing with the state’s extreme winter conditions.

They have not used it in Great Falls yet, but will use the mixture containing less than 25 percent sodium chloride when it is necessary to speed up melting after storms. When it gets below 10 degrees, sand is used instead as deicers won’t work in extreme cold.

Critics of all such chemicals say that sand and snow removal should be used universally, but snowplows leave berms of snow at the roadside, which melt on warm days leaving slippery, icy roads when the sun sets. Sand adds to air pollution and has to be cleaned up again, eventually adding to the transportation department’s expenditures.

The Montana Department of Transportation has used magnesium chloride on state highways within Great Falls in recent years. Johnson told the Tribune. The chemical will continue to be used in outlying areas, where there's no brine-mixing facility.

“Magnesium chloride works, but it's hard to get off of vehicles with a hose — it needs to be wiped off — and it costs about 70 cents a gallon,” Johnson said.
Salt brine dissolves when traffic crosses it and uses the same rust inhibitor in magnesium chloride agents, but brine only costs 20 cents a gallon. He doesn’t expect the brine solution to cause more damage to vehicles this winter. "It won't at all," he said. "It's less corrosive than the mags (magnesium chloride)."

You should draw your own conclusions about the deicers used in your area – deicing agents have to meet the demands of local safety and weather patterns. Corrosion from deicing agents to your second largest investment are not good, but traffic accidents are expensive and dangerous for everyone.
"Our total goal in this whole thing is to provide the safest driving surface that we can," Johnson said.

In Great Falls, the city only uses salt in its sand piles — about 5 percent salt to 95 percent sand — to keep the sand piles from freezing. "We're not doing anything different than we have," said Jim Rearden, director of Public Works.