U considers environmental impact in de-icing

Ice-melting chlorides damage waterways and cause erosion.

University sophomore Christian Boomgaarden and senior Troy Marschall spread ice melt Monday, March 11, 2013, on the University's East Bank.

Bridget Bennett

University sophomore Christian Boomgaarden and senior Troy Marschall spread ice melt Monday, March 11, 2013, on the University's East Bank.

Hailey Colwell

Winter ice is a constant threat to students’ balance on campus, but minimizing slips can also threaten the environment.

For years, the University of Minnesota has turned to anti-icing products like sodium chloride — common table salt — to prevent students from skidding, but these products come with negative environmental effects.

When ice melts, chlorides run into the sewer system and waterways like the Mississippi River, posing a hazard to wildlife. Chlorides also destroy plant material, usually grass on the side of walkways, said University Landcare supervisor Doug Lauer.

He said de-icing chemicals also seep into cracks in the pavement and break it down when the water refreezes, creating larger cracks and potholes.

Over the past four years, the University has spent an average of $139,130 on de-icing, said Facilities Management spokesman Brad Hoff.

Chloride is a permanent pollutant because it doesn’t break down or change form over time, said Brooke Asleson, watershed specialist for the Minnesota Pollution Control Agency. Because of this, the best way to remove it is just to use less, she said.

Chlorides can run into groundwater and build up over time, which could affect drinking water in the future, she said. High salt concentrations are beginning to affect native fish and insect populations, especially in landlocked lakes.

Asleson said large institutions like the University can play a significant role in protecting water resources.

The University works with MPCA to educate workers on how to apply the proper amounts of salt for safety while trying to make the least environmental impact, she said.

“People’s safety is very important but so are our water resources,” Asleson said.

A number of alternative anti-icing methods like beet juice and cheese brine have been tested, Asleson said, but both of these also have a negative environmental impact. Cheese brine, which is being developed in Wisconsin, has chloride in it, and beet juice is an organic material that can deplete oxygen in water.

Another alternative is porous pavement, which allows water to drain into parking lots instead of refreezing on top, she said.

Asleson said fixing areas that create icy conditions and removing ice and snow manually are other substitutes to anti-icing products.

“There’s really not a product out there that is completely safe for the environment,” she said.

Lauer said though these chemicals produce a variety of negative effects, their role in campus safety makes them necessary.

“It’s a balancing thing. Safety’s probably No. 1,” Lauer said. “Without treating walkways [and] roadways, we’d have many, many more injuries on campus.”

Balancing safety and pollution

Lauer said Landcare has taken steps every year to reduce its chloride use on campus.

Dyeing the ice melt blue makes it more visible on icy ground and helps prevent using more than necessary, Lauer said.

“You’re able to better see what you put down and not over-apply,” he said.

Pre-treating walkways with a salty brine before a snowstorm can also help reduce the amount of ice melt needed, he said, because it keeps snow from bonding to the concrete and creates a slushy layer rather than an icy one.

“You keep a good traction on your surface longer,” he said.

Lauer said Landcare performs salt-related repairs every year, like reseeding the turf along the sidewalk where the salt killed the grass, for example. University Parking and Transportation Services replaces concrete deteriorated by ice and salt, he said.

To prevent having to repair equipment, he said Landcare workers wash vehicles and equipment every time they work with chlorides.

Lauer said Landcare used to use sand to prevent slips, but sand can clog storm sewers and kill grass if it builds up. Road traffic can break up sand particles into dust, which can be harmful to breathe in, he said.

Though Landcare uses sand on extremely cold days when chlorides lose their effectiveness, Lauer said it has significantly reduced its sand use.

Though anti-icing makes campus safer, its environmental effects should always be considered, said biomedical engineering freshman Julia Karpas.

“Safety is important, but there should be a balance between the two,” Karpas said.

Though she said she dislikes having salt on her shoes, she prefers it to glare ice.

“It’s annoying, but I think I would rather have that than falling all over the place.”