Monday, February 6, 2012

State explains salt brine use

From the Burlington Free Press

Like our neighboring states, Vermont adheres to a "Safe Roads at Safe Speeds" policy during storm events. Delivering "bare roads" during a storm is simply not possible. However, we are constantly working to deploy new technologies and methods to improve safety for the traveling public and efficiency in the expenditure of their tax dollars. One new initiative that has been garnering attention lately is the use of salt brine. It's important to understand what salt brine is and how it differs -- or doesn't -- from conventional road salt.
Road salt is the same as the salt on the dinner table, NaCl, just bigger particles and not as clean. Salt brine is nothing more than salt and water. You can drop dry salt particles in a pile of snow, or mix salt particles with water to make salt brine -- you end up with the same thing, NaCl and H2O. In fact, our salt brine is made with the same salt that we are already spreading on the highways.
At times VTrans will mix additives into dry salt or salt brine to make the salt work better at lower temperatures. We mostly use a product called Ice B' Gone that is essentially water, molasses and magnesium chloride (another kind of salt). Ice B' Gone also makes the salt or brine sticky so it stays on the road better and has been documented by our own field testing, as well as other organizations such as the Pacific Northwest Snowfighters Association, to be less corrosive than salt. In fact, Ice B' Gone is rated by the EPA as being "Designed for the Environment."
Using sand and chlorides has a cumulative, detrimental effect on the environment. When we allow them into our water ecosystems it doesn't break down; it stays there until it's removed. Since large-scale removal is not technologically or economically feasible, it behooves us to limit the amount of sand and salt entering the environment.
That is precisely the aim of the salt brine effort -- it allows us to use less sand and salt while still providing a safe road for travelers. For example, in 2000-2001, total snowfall in Burlington was 122 inches. 16,540 tons of salt and 9,180 cubic yards of sand were required to maintain the state highways in the district. During 2010-2011, Burlington saw 128 inches of snow and that same district, using salt-brine, used about 11,000 tons of salt and 7 cubic yards of sand. The savings of 5,540 tons of salt and 9,170 cubic yards of sand is due -- at least in part -- to the use of salt brine. VTrans is confident that continued research, training and experience, will assist in the achievement of even greater savings without sacrificing safety. 
Some have expressed concern that salt brine is harder on cars than conventional road salt. Salt brine is the same chemical composition as dry salt mixed with ice, snow or rain. Less salt used translates into less corrosion potential whether it is dry salt or wet salt. Studies have shown that the blends we use actually lower the corrosive properties of salt. According to the Margaret Chase Smith Policy Center at the University of Maine, the total number of chlorides in the environment has a much stronger influence on metal corrosion than the type of chloride-based deicer or the method of application. While some may speculate that salt brine is more corrosive to vehicles, the science and studies to date have not shown this to be true.
Our goal is to perform winter maintenance in the safest, most cost effective and environmentally friendly manner possible, and we believe salt brine is one of the tools which will allow us to do just that. But no matter what combination of tools and methods we employ in our effort to manage road conditions, public safety on our highways still depends largely on the behavior of individual drivers and the collective willingness to slow down when conditions warrant it. In the end, the safety of everyone on the road depends on the choices you make.
Scott Rogers of Waterbury is director of operations at the Vermont Agency of Transportation.

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