Posted by Angie Hong | Posted in Keeping water clean, Local Achievements | Posted on 07-12-2010
For the first 23 years of my life, I didn’t just hate running. I detested it. You wouldn’t see me trotting so much as a mile unless a bear was chasing me, and even then I might just choose the lesser of two evils and let the bear eat me. When a girl I knew in college slipped on an icy trail a broke her knee while out on a winter night’s jog, I thought, “Who are these people that are crazy enough to run at any time of year, let alone in the winter?” Yes. All these thoughts flashed through my mind at 5am Wednesday morning as I headed out for a morning run, slipped on a small patch of ice and barely caught myself before doing the splits in the middle of the sidewalk.
Most people who live in the upper Midwest have a love–hate relationship with winter. We love snow and ice when it’s the weekend and we are sledding down a hill or drilling a hole in a frozen lake to fish. We hate snow and ice when we are shoveling our driveways or driving white-knuckled to work. Unfortunately, there is no magic solution to snowy, icy roads. Our city, county and state road departments have traditionally relied on an army of snowplows and a whole lot of salt to keep the roads safe for travel. In recent years, however, the state and many local communities have begun to take a more scientific approach to winter road management.
While good, old-fashioned salt (sodium chloride) is still the deicer of choice for many municipalities and private parking lot contractors, it has a number of limitations. To begin with, dry rock salt is completely ineffective at melting ice when temperatures are less than 10º and only minimally effective at temperatures less than 15º. This is a major problem when you live in the nation’s ice box and 15º is a balmy winter’s day.
More frightening is the fact that as salt dissolves in water, the chloride ions remain intact and can move through the environment without breaking down. Almost all of the salt spread on our roads and parking lots eventually migrates to surface or ground waters and like sugar in your morning coffee, once it’s there, it’s almost impossible to remove. There is a real danger that some of our drinking water resources will become unusable in the future as chloride gradually accumulates in the environment. Already there are some streams in the metro area with chloride levels high enough to kill off fish and benthic organisms (the base of the food chain). Furthermore, when salt finds its way into streams and lakes, it prevents oxygen and nutrients from cycling normally and can also release toxic metals from the sediment.
In light of these concerns, the Minnesota Pollution Control Agency, Fortin Consulting and the University of Minnesota Local Technical Assistance Program (LTAP) have been organizing trainings for the past five years to help public works and private contractors employ a more scientific approach to keeping roads and parking lots safe in the winter. During the workshops, attendees learn how to pre-treat roads when storms are forecasted, precisely measure the rate of salt and chemical application, use salt alternatives when necessary, and target deicers to the areas that need it the most – intersections, hills and curves.
Locally, several east metro communities, including Stillwater, Woodbury and Cottage Grove, have made substantial changes in their winter roads maintenance as a result of these trainings. Last year, the South Washington Watershed District provided Cottage Grove with a $50,000 cost-share grant to help the city retrofit its fleet of deicing trucks with GPS and pavement temperature sensors. The upgrades will help road crews to target their deicing efforts on the trouble spots that need the most help, and will also reduce Cottage Grove’s winter salt use by 15-20% (780 to 1040 tons of salt), which will translate into big cost savings for the city. In addition to the winter fleet upgrades, the South Washington Watershed is working with the Washington Conservation District to monitor chloride levels in snowmelt at two locations in Cottage Grove over the next six years.
Although most winter salt is used for parking lots and roads, we can all help to protect our surface and drinking water resources by limiting the amount of salt we use on sidewalks and driveways and cleaning up any remaining salt after the ice thaws. Keep in mind that only one teaspoon of salt is enough to pollute five gallons of water, which means that a single 50-pound bag of salt can contaminate over 10,000 gallons of water. No one wants to hear it, but early shoveling really is the best weapon against slippery sidewalks and driveways. Then again, if you spend enough time shoveling the driveway, you can probably skip your morning run.