Green scene:
Fighting the white stuff

by Michele Regenold

Despite snow and ice, Americans like to keep moving. They expect their roads and streets to be passable and their planes to keep flying.

On the roads

Plowing snow is the most familiar way of keeping streets and roads clear, but it’s just one tool. The government agencies responsible for roads usually use sand and chemicals too. But what effect do they have on the environment?

The City of Des Moines, Iowa uses four different materials to handle snow and ice:

1. Sand
2. Salt (sodium chloride) in solid form and in a liquid, 23% solution called brine
3. GeoMelt, a product made from beets
4. Liquid calcium chloride

William Stowe, assistant city manager of public works/engineering in Des Moines, says that the main environmental concerns about using these materials are air and water quality.

Sand causes dust when it’s put down and as traffic rolls over it. The city picks it up with street sweeping equipment when it’s warmer than 32 degrees Fahrenheit.

In Iowa the bigger concern is water quality. If sand gets into streams, it can make the water cloudy. It also adds to the sediment.

Sodium chloride and calcium chloride aren’t too great for water quality either. If they get into a stream, they have a negative impact on organic organisms.

Cost of the materials is an issue. Brine costs about five cents per gallon. GeoMelt, which has much less negative impact, costs about 50 cents per gallon.

Stowe says, “We’re very conscious about using materials sparingly and only if there’s a public safety issue.”

Chemicals and planes

The deicing fluids used on aircraft are toxic to aquatic life in high concentrations (see this issue’s feature story “Winter weather flying: How do they do that?”). When the deicer is sprayed on planes, some of it falls onto the ground, where it mingles with melting ice and snow.

At the Des Moines International Airport, this untreated runoff used to end up in Yeader Creek, where much of the fish and insects disappeared. Since 2000, the airport has had a special underground system (it holds four million gallons) that collects the contaminated runoff from areas where planes are deiced. This gets fed through a special pipe and carried to the city’s wastewater treatment plant.

John Wheeler, the Des Moines International Airport’s environmental manager, says there were no signs of aquatic life in winter of 1997, but “there’s pretty good aquatic life now.”

Protecting the environment isn’t cheap. The airport spent over $10 million to build and operate its runoff containment system.

It’s a tricky balancing act between public safety and the negative environmental impacts of snow fighting materials. Stowe says, “We’ll always weigh on the side of public safety.”