Low-salt diet has some roads getting greener
Old-fashioned brine lets municipalities save money, help safeguard environment
The science of making streets safe during winter storms is potholed with problems.
Tons of sand dumped on roadways can pick up contaminants and clog storm drains and must be swept up each spring.
Anyone who has driven behind a truck dispensing rock salt knows that a lot of it often bounces off the roadway, wasted.
And a growing body of research shows that salt used to combat ice and snow can corrode vehicles and bridges, kill vegetation, and contaminate drinking water supplies.
While the hunt is on for more environmentally friendly road treatments, salt still reigns supreme because of its low cost and effectiveness. Now, however, a small but growing number of Massachusetts communities are rediscovering an age-old solution: brine.
The mixture, also called liquid salt, simply combines rock salt with water, making a mixture that is between 23 percent and 26 percent salt. The liquid can be applied to roads before a storm. It settles into crevices on roadways, creating a layer that prevents ice and snow from creating a bond with the pavement.
Its application dramatically cuts down on the amount of salt that enters the environment, compared to using pure rock salt.
Money is also saved by using less salt and applying it during regular working hours, not during overtime shifts when labor costs amplify.
“We are always trying to find cheaper ways of doing things and better ways,’’ said Kevin Cafferty, engineering supervisor for Scituate, who used brine for the first time during the Christmas weekend nor’easter.
It worked so well the need for sanding was reduced, he said, although that will not always be the case. Each storm brings its own conditions. And each municipality will decide when to apply brine depending on conditions — too early could mean it is worn away by traffic, too late could make conditions slick. In Scituate, Cafferty tries to time it about 48 hours before a storm.
Several other municipalities have turned to brine in recent years, including Boston, Fall River, and Bedford. Of course a forecast can be wildly wrong, but public works directors say they apply brine when confidence in the forecast is high — and road treatments are often needed even when less snow falls than forecast.
Cities, towns, and the state spared no amount of salt and sand over the decades in efforts to keep the roads safe. But eventually, the chemicals and volume of sand were shown to injure birds and other wildlife and even sometimes to seep into drinking water, potentially causing problems with people who have hypertension. Today, many municipalities do not allow salt near watersheds or aquifers.
“If you think about a glass of water and table salt, it dissolves,’’ said Tom Maguire, regional planner for wetlands for the state Department of Environmental Protection. “It can get into the groundwater.’’
A growing suite of green deicing products have entered the market, but their cost can be dramatically higher than traditional methods.
Rock salt, or sodium chloride, which lowers the freezing temperature of water, is used in most places. Other salts, such as calcium chloride and magnesium chloride, are used in colder temperatures because rock salt works only in relatively mild ones.
Brine is hardly new. It’s long been a remedy for homeowners to protect sidewalks and driveways because it’s inexpensive, easy to make — in pails or kiddie pools — and works well.
Brine makers were not practical for many public works departments because of the difficulties in testing salinity; if the salt-to-water ratio was off, it would be ineffective or, worse, freeze on the road. But in recent years, companies have improved automatic brine makers’ abilities to get the percentages right.
Scituate and other communities have bought brine makers from Cargill Deicing Technology, a division of Cargill, an international company that manufactures a wide range of food, financial, agricultural, and industrial projects.
“We looked at the headaches with brine production and we created solutions for that into our machine,’’ said Sean Riley, marketing manager for Cargill Deicing Technology, which makes other green products for roadways.
Riley said most communities recoup the cost of the brine maker in four to eight years, depending in part on the weather.
Bedford’s Public Works director, Rich Warrington, said to do a first application for town roadways will cost about $500, as opposed to $4,500 if the town uses rock salt. This is the first winter the municipality is using brine.
“It’s working extremely well,’’ Warrington said. “It prevents the snow from caking and bonding to the road, and when we do plow, with the brine we will get more a squeegee effect.’’
Fall River began using brine two years ago; Kenneth Pacheco, director of community maintenance, said it is proving effective.
“Fall River is a city of hills; we have 10 or 15 that are treacherous. The slightest bit of snow makes it into a ski slope,’’ Pacheco said. “This helps.’’
“The whole goal,’’ Warrington said, “is to have safe roads but don’t kill the environment in the process.’’
Beth Daley can be reached at firstname.lastname@example.org.