During wintry weather, sand and salt or other de-icers are often used around the home and on the roads. While they help prevent broken bones and save human lives, they can have a negative affect on the environment.
Of course, environmental impact is not the only consideration when choosing among the hundreds of traction and ice melting products on the market. Other factors include performance: i.e., effectiveness (the more effective it is and the longer the residual effect, the less you need to use) and adherence on different surfaces over a range of temperatures; cost of the product, purchase or retrofitting of application equipment, for labor for application and cleanup, and repairs associated with corrosion; scale (e.g., a home sidewalk vs. miles of highway); availability; use and storage considerations such as ease of application, training needed; residues (e.g., on concrete and carpets); and corrosivity, especially to reinforcement steel on bridges, and to concrete and vehicles.
Sand seems pretty innocuous at first blush. It is an inert, natural substance. But it has to be reapplied repeatedly during snowfall. It accumulates on roads and can clog up storm drains. When ground up by traffic, it creates dust. It runs off roadways and can choke water channels and smother fish spawning grounds. New stormwater controls require that sand be swept off roads and cleaned out of basins on a regular basis. As Woodstock Highway Foreman Dwight Ryniewicz noted, “three or four workers driving a sweeper followed by dump trucks for three months use a lot of fossil fuel.”
Urea is actually a fertilizer. It is not corrosive, so it is safe for concrete with steel in it. When applied in limited quantities, it does not have a negative impact on vegetation. However, it can cost about five times as much as rock salt.
Salt (Sodium Chloride): You may have noticed that Sugar Maples along a road tend to change color early in the fall. Some roadside vegetation like Sugar Maples and White Pines are very sensitive to road salt. Direct salt spray on vegetation damages tissues. Salt in the soil changes soil chemistry and plant metabolism, causing stress. Animals like moose and deer may be attracted to salt and cause car accidents. Salt (and some chemical de-icers) can injure an animal’s paws.
Rock Salt is cheap, but it doesn’t work well below 22°F. When snow mixed with salt melts, the sodium and chloride ions can flow into surrounding surface waters and through the soil into groundwater. High salt concentrations can impact the survival of Wood Frog and Spotted Salamander eggs and embryos. In addition to changing water chemistry, when salt additives like sodium ferrocyanide and chromates dissolve in water, they are toxic to aquatic life.
Liquid Brine (Calcium Chloride) works at temperatures as low as -25°F. But it is expensive and leaves an oily residue if applied too heavily. Some highway maintenance departments are switching to a program where the road is pre-wetted with liquid brine, which minimizes overspray and the amount of sand or salt that need to be applied by helping it stick to the road.
Calcium Magnesium Acetate (CMA), a liquid de-icer made from limestone and acetic acid, is considered more environmentally friendly. It is reportedly non-toxic and biodegradable. Because it is much less corrosive than salt, it is often used on bridges, etc. But the cost is 4-5 times higher than Calcium Chloride. Application requires special spray tanks. It must be stored at temperatures above freezing until use, and if a container is left unsealed, it will go bad.
Dwight Ryniewicz has been looking into a product called Ice B’ Gone, which contains Magnesium Chloride and Ice Ban, a distillery byproduct. Ice Ban was supposedly discovered when a Hungarian worker at a vodka distillery noticed that, no matter how cold it got, the river receiving discharge from the distillery never froze. Ice B’ Gone is noncorrosive, water soluble, and biodegradable. When falling snow hits it, it activates and heats up, which keeps the snow from accumulating. Ice B’ Gone is already used extensively in New York, Canada, and Washington, and in Connecticut towns like Ledyard, South Windsor and Hartford. These highway maintenance agencies are thinking about costs and effects that last longer than the snow does.
To help protect the environment around your home, you can shovel more often, use an ice-chipping tool, minimize the amount of any product you do use, avoid dumping snow containing de-icers onto sensitive vegetation or into water bodies, and look for products that do not contain salt or toxic chemicals.