For those involved in choices about snow- and ice-removal products and their application, the answer is a balancing act, one that's based first and foremost on concern for public safety, that uses chemicals least harmful to the environment but most responsive to varying temperatures and forms of precipitation.

When it comes to managing Columbia's roads and walkways in a winter storm, Richard Bussert, Manager, Landscaping/Grounds, Columbia University Facilities, says "safety to the campus is the top priority, and products are applied that are safe for pedestrians." He says that his department tries "to use salt at the right place and rate" in order to minimize damage – on the campus perimeter, for example, and less within proximity to plants and shrubs. But, he says, salt usage is "based on effectiveness and price, which are both good – and there's a limited arsenal of snow-removal products to choose from."

Besides rock salt, Bussert says the Morningside campus deicing inventory contains calcium chloride, and LESCOMelt II.

Although calcium chloride is less harmful to vegetation than rock salt, it is corrosive to concrete and metal. Calcium chloride is effective in very cold temperatures when rock salt does not work and is three times more expensive than rock salt.

"When I have a storm with temperatures between 25 and 30 degrees, LESCOMelt II is my product of choice," Bussert says. The compound contains potassium and magnesium chloride, and "is much more environmentally friendly," he says. It's twice the price of rock salt.

Bussert points out that "each storm has its own character." He cites the recent Valentine's Day storm as an example: "What made this storm difficult to manage was not the snow, but the mixed precipitation, which changed from snow to sleet to freezing rain several over a period of at least eight to 10 hours. Compounding this was the fact that the ground and surfaces were frozen."

When there's "fluffy snow," Bussert says, it's removed as quickly as possible, followed by application of a deicer as needed. On Valentine's Day, however, he says "we had to remove the snow and ice every hour or two, often in one-inch layers, then apply the product, let another inch or so accumulate, remove, reapply ice melt – over and over."

Because the temperatures were relatively low that day, the ground was very cold, and the next day's forecast was for cold temperatures, Bussert says "we had to use more calcium chloride" than rock salt or LESCOMelt II.

Last Nov. 6 Bussert presented a "Snow Season Kickoff" for his staff – part of the ongoing training he oversees on deicing products and their application. "Correct application is every bit as important as the products we use," he says.

Bussert, who came to Columbia in January 2006, says he hasn't wanted to buy new ice-melt products until the existing inventory has been lowered. He continually researches new products and says he "will order items for next winter that can offer the best combination of effectiveness, safety to plants, people and the environment, and price."

High on the Palisades in Rockland County, N.Y., Lamont-Doherty Earth Observatory treats its roadways with rock salt from a dump truck with a spreader, says Patrick O'Reilly, Assistant Director, Facilities and Engineering.

Sidewalks are treated with proprietary mixes of calcium magnesium acetate and rock salt. O'Reilly says LDEO "hasn't had an adverse environmental impact from the salt."

He says it flows into the Hudson River, whose salt line goes as far north as Poughkeepsie. "We haven't seen foliage browning," he says, "although the salt does eat concrete."

O'Reilly, who's been at LDEO for two years, says LDEO is eager to incorporate some new best practices surrounding environmentally sound deicing materials and applications for winter 2008. The plan is to buy a new salt spreader with a brine tank for the dump truck.

The new equipment will allow for more environmentally sound application. With the brine tank containing a mix of dissolved salt, roads will be wet down before a storm with the brine solution. Because the roads will have been pre-moistened, when the storm arrives and salt is applied, it will stick to the roadway rather than bounce – thereby lessening the amount used.

"This is basically state of the art now for the municipality, and how they're doing their salt program," O'Reilly says. LDEO is in Orangetown, where O'Reilly attended a best practices seminar sponsored by the highway superintendent

O'Reilly says LDEO also "needs a new home for salt." He says LDEO normally keeps 65 tons on campus at all times, and "the main thing to accomplish is to keep it protected because we don't want brine run-off."

Among colleges and universities grappling with environmentally sound snow- and ice-removal, the University of Michigan stands out. Environmental stewardship "goes way back here," says Diane Brown, UM Senior Information Officer, Facilities and Operations.

When Brown arrived at Michigan in 1999, she says, they had made a commitment to reduce salt and sand usage by 50 percent in five years – and have achieved it. She describes their process as "lots of trial and error, and modifying as needed."

"Different materials work at different temperatures, and there weren't many on the market," she says. "There were lots of problems with applications – you can't hand-spray on sidewalks. They tried to adapt applications to lawn mowers – but they're only designed to run in the summer!"

The effort was directed by a cross-university team whose work included an analysis not only of short-term costs of new materials and applicators, but also the long-term impact of continued salt usage. "Factoring all this mitigated the price differential," Brown says.

According to the Grounds and Waste Management Services section of Michigan's Plant Operations website, magnesium chloride is the "primary granular deicer for walks, steps, plazas, entryways, etc." Like LESCOMelt II, magnesium chloride is environmentally safer than rock salt and calcium chloride. It melts at lower temperatures than LESCOMelt II, and is thus more effective in a Michigan climate. Magnesium chloride also costs slightly more than LESCOMelt II.

Michigan's goal to reduce salt use by 50 percent has hinged in large part on the use of liquid deicers on parking lots and roads. According to the website, the product of choice is CALIBER M – 1000, a corn derivative. Its application as a pre-wetting and deicing agent is consistent with the process that Patrick O'Reilly at LDEO envisions for winter 2008.

The bottom line in the effort to balance environmental sensitivity with the multi-faceted questions about on-campus deicing and public safety seems to be that walks and roadways are outdoor laboratories where answers are often difficult to come by and rarely absolute. All, however, in the University of Michigan model – one of trial, error and trade-off.

(Photos taken by Gene Roman)