Smarter Living: Getting About
Why Communities are Trying New Ways to Clear Snowy Roads
For ten years Seattle's eco-friendly sand-based strategy to control snow was more than adequate to manage the average 13 inches of snowfall the city received each winter. But in December of 2008, when over a foot fell--and stuck--on Seattle roads for nearly two weeks, the virtually undrivable sandy snow pack led to accidents and abandoned vehicles on highways, nearly incapacitated the public transit system, forced police officers to respond to calls on foot, and kept garbage trucks from picking up trash and recycling. Seattle is now committed to dumping 200 pounds of granular salt per mile on hills, bus routes and arterials in the event of another snow or ice storm.
In U.S. regions where heavy snowfall makes regular winter appearances, salt has been a longtime, and increasingly utilized, method for melting ice and snow to keep city rhythms in motion and driving conditions relatively safe. A 2005 study published in the Proceedings of the National Academy of Sciences showed that, on a national level, the use of rock salt to melt street ice has increased a hundredfold since 1940. The state of New York, which sees an average of 40 inches each winter and more than 70 inches in roughly 60 percent of the state, meets its snow and ice control policy with 225 pounds of salt per lane per mile for temperatures between 23 and 32F and 275 pounds for temperatures between 15 and 23F.
All that salt doesn't stay on wet winter roads but seeps into nearby soil--causing soil erosion and killing vegetation--and into rivers and streams where it harms freshwater organisms. In 2005 a survey of freshwater sources in the Northeast conducted by the University of Maryland found that certain streams were 25 percent as salty as seawater, and that the extra salt was killing animals and fish. Chloride salt de-icing treatments can also corrode concrete and metal, and can be hazardous to pets and wildlife that ingest it. In Quebec and Ontario, road salt is associated with higher incidences of moose/vehicle accidents because excessive salt toxicosis causes the animals to lose their fear of vehicles and humans. In some regions where salt has been used in large quantities for many years, the buildup in drinking water supplies presents public health concerns including hypertension, high blood pressure and cardiovascular, kidney and liver disease.
Growing awareness of the many hazards that come with road salt has some municipalities making tough decisions. Salt is an affordable and highly effective method to prevent traffic accidents and keep the local economy from coming to a grinding halt in the event of a snowstorm. But its costs also include wildlife loss, soil erosion, road damage and contaminated freshwater supplies. Sand may seem a reasonable alternative to salt, but many communities have stopped using it because it clogs sewers, muddies waterways and is costly to clean up. There are safer, albeit pricier, alternatives that communities are trying out. On certain roads and bridges in West Virginia, calcium magnesium acetate (CMA) is used instead of salt because it is noncorrosive to metals and nondestructive to concrete and other highway materials. Another salt alternative is potassium acetate (KA), which is gentler on the environment and on road and highway materials.
Vermont and Syracuse, New York, are trying a low-salt alternative consisting of rock salt and briny water, which is applied to roads before the storm to prevent ice from bonding to surfaces; and in Maryland, brine is mixed with sugar beet molasses to help the salt adhere to the road, reducing runoff and the need for repeated applications.
In Seattle, where snowy conditions are so infrequent that the roads only need attention once, maybe twice, a year, salt doesn't pose a serious environmental threat. But in areas where snowplows and salty roads are regular winter characters, alternative de-icers are becoming increasingly urgent. Check with your department of transportation for the snow maintenance plan in your city, and urge your mayor to consider a safer way to keep the roads safe.
- Spread sand or gravel over icy paths and driveways, and sweep up afterward both for reuse and to keep them out of streams.
- Cover key areas with heavy plastic before storms, and pull up the sheeting immediately after the storm to avoid it freezing into place.
- Only use de-icer on the most dangerous spots, and use small amounts. Apply before the ice is too built up.
last revised 2/3/2012