by Lindsey Hodel
Homeowners and street crews use salt and sand on icy sidewalks and roads to make them safer to navigate, mostly because salt and sand are cheap and abundant. But they aren't good for the environment or for buildings, roads and cars.
Even when used in small amounts, salt will leach into surrounding soil, changing the soil's composition and making it hard for plants to survive. Salt potentially can contaminate groundwater, too, and it's highly corrosive to paved surfaces, buildings and cars.
Even though sand is not corrosive, it's still not a great choice for the environment. If sand is not swept up from roads every spring, it can clog storm drains and cause flooding. When it reaches rivers and lakes, sand buries aquatic floor life, fills in natural habitats and clouds water. Sand also absorbs and carries contaminants like oil and grease into bodies of water.
Fortunately, salt and sand aren't the only weapons with which to battle icy weather. But, the first step for any homeowner developing a more environmentally friendly snow removal routine is decreasing your use of chemicals, says Malama Chock, a member of the Salt Use Improvement Team at the University of Michigan. The more you use physical methods instead of chemicals, the better.
But in some climates or areas with heavy traffic, chemical de-icers may be necessary to keep roads and sidewalks safe. If you need a chemical de-icer, liquid sprays are more efficient than granular products because they cover a larger surface area, Chock says. Most importantly, she recommends using chemical de-icers before a storm hits rather than after, a concept called anti-icing. The key is timing the application of de-icers to minimize the possibility of wash-off by rain. You don't have to use nearly as much of a chemical to prevent ice from forming as you do to remove it after it has hardened.
Chemical alternatives to salt and sand are becoming more commercially available, but their availability in small quantities for homeowners remains limited. After testing various de-icing chemicals, the Michigan Salt Team now uses a magnesium chloride solution called Caliber M1000. Rob Doletzky, Salt Team member, says Caliber products are not as harmful as salt. Caliber de-icers reduce corrosion and have an added "stickerspreader" similar to corn syrup so they bind to concrete and won't track inside as much. M1000 comes in liquid form and costs about $9 a gallon from Glacial Technologies [ www.anti-icers.com; (330) 863-9531].
Besides magnesium chloride, other alternatives to salt and sand are calcium magnesium acetate (CMA), calcium chloride and potassium acetate. For a complete list of deicers and their pros and cons, see the chart on Page 57. Some can be combined to increase effectiveness, but check the label of the products before mixing.
Organically based substances like CMA and potassium acetate are definite improvements over salt or sand in terms of corrosiveness and environmental safety, but they do remove oxygen from bodies of water into which they are sometimes washed. They also are more expensive, although the cost will vary significantly by region. "Generally, the more environmentally friendly and less corrosive a product is, the more it costs," Doletzky says. "In a sense, you get what you pay for."
Before choosing a de-icer, consider your geographic conditions and your yard size. For most homeowners, the main concern is having to replant vegetation that salt or oth er chemicals can kill, says Russ Alger, director of the Institute for Snow Research at Michigan Technological University. He says different plants respond differently according to their salt sensitivity. Signs of salt damage to vegetation include browning of needles or foliage, branch dieback and /or lack of flowering. The overuse of de-icers will kill plants along roads or sidewalks.
A few factors to consider before choosing a chemical de-icer are its impact on plant life, concrete, vehicles, shoes, pets and carpet, and associated health hazards.
A new method Alger is researching involves applying an epoxy overlay system to pavement to make de-icing chemicals more effective. He has conducted trials in New Jersey and in Michigan and will be testing further during the coming winter months.
The trials involved applying the epoxy and a hard, spongelike material to pavement during the summer and then using a light coating of a de-icing chemical in November. "In some conditions, one coating will last all winter," Alger says. The method could be useful where the environment is especially fragile, like on a bridge over a river.
Ultimately, it's almost impossible to determine which de-icing chemical is the best for homeowners because it depends on the specific conditions of an area, Alger says. "Out of all the products I've looked at, there's no one magical chemical," he says. "There are positives and negatives to each. Any time you put something into the environment, you face detrimental effects."
For this reason, homeowners should be mindful of how much of a chemical they use. "Street departments have figured out using too much of a chemical is a waste of money," Alger says. "But for homeowners, the cost difference isn't as great so they tend to use too much."
Alternative de-icers may not be practical if they are not available in your area, or if the area you need to treat is small. If you do opt to use salt, follow advice from Wilfrid Nixon, professor of civil, environ mental and mechanical engineering at the University of Iowa. "You should only use 0.08 of an ounce of salt per square foot," he says. So, multiply your square footage by 0.08 and use only that amount.
Safer de-icing chemicals cost about three to four times more than salt or sand, but instead of dwelling on spending more money focus on what you're saving.
Works to: Minus 25 degrees
Advantages: Produces heat as it melts; less harmful to vegetation Disadvantages: Corrosive to metal; leaves residue harmful to carpet, tile, shoes; attracts moisture from the air
Cost: Three times more than salt
Works to: Minus 13 degrees
Advantages: Attracts moisture from the air; corrosive Disadvantages: Keeps pavement wet if it attracts too much moisture from air; corrosive to metal
Cost: Two times more than salt
Works to: Minus 75 degrees
Advantages: Safer than salt for steel structures; performs very well; noncorrosive, biodegradable Disadvantages: Could cause slickness on pavement; lowers oxygen levels in bodies of water
Cost: Eight times more than salt
Calcium Magnesium Acetate
Works to: 25 degrees
Advantages: Won't harm environment if used sparingly; biodegradable Disadvantages: Subject to dilution and refreezing; could cause slickness on pavement
Cost: Twenty times more than salt
Mother Earth News