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Public Radio's Environmental News Magazine (follow us on Google News)

A Road Salt Saga

Air Date: Week of

A century ago, workers cleared snow from the roads by dousing it with flaming gasoline. Today we clear with salt, by pouring about 10 million tons of it on our roads every winter. But all this salt is taking a toll on the environment. A handful of states have stopped using the corrosive cleaner and they're trying a vinegar like alternative. Living on Earth's Liz Lempert reports.


CURWOOD: A century ago New Yorkers cleared city streets of snow and ice by dousing them with flaming petroleum. Today, spreading salt is the way most road crews handle the problem. We dump an estimated 10 million tons of salt onto our roads in an average winter. But all this salt takes a toll on the environment, and as a result a half-dozen states have stopped using it altogether. Many other states are beginning to experiment with snow-melting methods that promise to clear the streets without hurting roadside ecosystems. Living on Earth's Liz Lempert has been exploring some of the alternatives.

(Trucks, plows)

LEMPERT: It's 3 in the morning and snowing at the Massachusetts Highway Truck Depot just south of the New Hampshire border.

(Man: "That's good!" Trucks, plows roll.)

LEMPERT: Highway operations engineer Gordon Brose is heading across the parking lot to meet an incoming fleet of 5 large snow plows.

BROSE: Long as you're dressed for it, it's not too bad.

LEMPERT: Brose consults with the foreman on what the plows should spread on the roads tonight.

BROSE: They're saying that it's going to turn to rain at daybreak, which is usually when it starts to warm up a little bit. The sun is our friend when it comes to snow fighting, and the sun is worth multiple loads of salt, that's for sure.

LEMPERT: But the road crews aren't waiting for daylight. In the darkness, a forklift dumps a salt mixture into the truck's loaders. Road salt makes it easier for plows to scrape streets clean, but it's hard on the environment, says Zev Ross of the River Alliance of Wisconsin.

ROSS: Trucks will go through the street and they'll dump salt, and salt will mix with the snow and melt the snow, and the runoff will go into the gutters and go straight to lakes or streams. Or it will go through the soil. Salt is very mobile in soil and it goes straight down to the groundwater and ends up in our water supply.

LEMPERT: Salty well water poses a health threat to people with hypertension. Salt runoff into rivers and streams can kill fish, and salted roads attract wild animals. The state of Maine had to begin lining its highways with moose repellent to cut down on the number of collisions. But it's corrosion that's causing states and cities to rethink their use of salt. Salt causes an estimated $750 million worth of damage to roads and bridges each year, and causes $2 billion worth of damage to cars. In hopes of curbing these costs, Washington State has stopped using salt altogether. Department of Transportation maintenance engineer Dale Keep says the move was prompted in part by public concern.

KEEP: And most of our customers, you know, they want their roads open but their first question is, when talking about using chemicals, de-icers, is what will it do to my car and what will it do to my environment?

LEMPERT: To clear the roads in areas of Washington where there's sensitive fish habitat and many bridges, crews now use a vinegar-like substance called calcium magnesium acetate, or CMA. CMA is non-corrosive. It doesn't hurt plants or contaminate drinking water. And because it smells like vinegar, it doesn't attract animals. The problem with CMA is that it costs around $900 per ton, far more than a ton of salt, which costs just $30. But Oregon transportation consultant Dick Parker says that when you factor in the costs associated with salt corrosion, CMA isn't such a bad deal.

PARKER: Obviously we would love to see it significantly cheaper than what we're now paying for it. But even at prices we're paying we're still able to show savings.

LEMPERT: And there's promising research that could bring down the high cost of CMA. Scientists at Ohio State University have discovered that CMA's most expensive component can be made out of fermented cheese whey. The new process could make CMA 4 times cheaper, but that's still not as cheap as salt. And for this reason, advocates of salt say it's still the most practical de-icer around. Salt Institute president Richard Hannemann says salt won't cause serious environmental problems if it's used properly. For instance, he says, road crews can be taught that more is not always better.

HANNEMANN: Obviously a truck driver who was told that 300 pounds per lane mile will be good to keep the roads safe might conclude that 600 pounds per lane mile would keep it twice as safe. And so we have some education to do.

LEMPERT: Many cities have reduced their salt use by mixing it with sand. But sand has its own environmental problems. As sand dries it's blown up into the air, adding to particulate levels. Denver had to stop applying sand because it was exacerbating the city's air pollution problems. The bottom line, says Washington State's Dale Keep, is there's no perfect solution.

KEEP: There are prices to be paid for whatever we choose to do or not do. For example, if we choose to do nothing and the city shuts down, there's some prices to be paid for that. If we go out and just simply plow, well we're burning fossil fuels.

(A horn beeps. Snow is shoveled.)

LEMPERT: It's the morning after a winter snowstorm in Boston. Residents are busy shoveling their driveways and brushing snow off their cars. But thanks to road crews, the streets are as bare as on a summer' day. And that, say some environmentalists, is the problem. While they're heartened by advances in technology and the use of more benign chemicals like CMA, they caution that dumping millions of pounds of any chemical into the environment will take a toll. The real issue may be our unwillingness to change our driving habits. As long as motorists expect summer-like driving conditions in the middle of winter, there's likely to be a trade-off. For Living on Earth, this is Liz Lempert reporting.



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