Montana DOT Begins Using Salt Brine, Limits Use of Magnesium Chloride
December 7, 2011
Officials say salt brine is a less expensive and less corrosive alternative to magnesium chloride, and it's more effective than pure rock salt. It's already in use in the Kalispell and Whitefish areas as well as Missoula, Helena, and Butte.
The debate surrounding the use of corrosive chemicals to clear roads of slush, snow and ice is a long and loud one, but official in Montana say spraying liquid salt brine will provide the snow melting capability they need, without the corrosive effects of salt and magnesium chloride.
The only downside to the brine solution, they admit, is that it can't be used at temperatures below 18 degrees because it freezes.
The brine is a solution of 23% salt mixed with water with a corrosion inhibitor added. It is sprayed from trucks in liquid form onto road surfaces to melt snow and ice.
MDT officials say they will continue using sand, along with pure rock salt and magnesium chloride in limited instances, mostly in areas where the brine is not available or when temperatures are too low. Rock salt is often mixed with sand to prevent the sand from freezing. Salt and Magnesium chloride cannot be mixed together.
Sanding roads frequently causes dust, and forces the state to sweep the roads to pick up the sand.
The state had also experimented with a corn-based product but discontinued its use after receiving complaints about its bad smell.
Corrosion and Cost
While the brine solution is said to be less corrosive than magnesium chloride or salt, residents in the Great Falls area are concerned about the impact of the product on their cars.
The Great Falls Tribune quotes Mick Johnson, district administrator for Great Falls Division of the Montana Department of Transportation as saying the 23% brine solution is less corrosive the pure salt because the salt is at a lower concentration.
"First of all, we're not spreading salt, we're spreading salt brine," Johnson said. "It's 23 percent salt."
Raw salt is placed on roads in some states, but that's not what will happen in Great Falls, he said.
"Salt dissolves in nature," Johnson said. "It's a natural element."
Johnson also told the paper that magnesium chloride costs about 90 cents a gallon compared to the brine, which costs about 20 cents a gallon.
According to KFBB Television of Great Falls, last year MDT used around 240,000 gallons of magnesium chloride in Great Falls at a cost of $216,000. If MDT needed to use the same amount of salt brine this year as magnesium chloride last year, MDT would save about $120,000.