How rethinking design could reduce the need for road salt

Parking lot sloped toward accessible parking
A parking lot during a recent winter shows water from a melting snowpack running across a parking lot, creating potentially slippery areas around handicapped parking stalls. Moving the snow storage area to a low spot and relocating the storm drain could help redirect the water and reduce the need for deicing salt. It's an example of the low-salt design strategy some Minnesota cities are testing to prevent chloride pollution.
Courtesy of Bolton & Menk

Lori Haak doesn’t need to go far to see how a building’s design can create messy winter problems. Her own Eden Prairie neighborhood is a case in point.

During more typical winters, melting snow from the massive roofs of the mid-1980s multifamily development drains into gutters that overflow in front of the buildings’ entrances, leaving slick spots that can be treacherous for its residents.

“I’ve watched so many of my elderly neighbors have trouble navigating this, because the water — it just doesn’t have a place to go,” she said. “So all of us are using a ton of salt all the time to try and stay ahead of that.”

That bugs Haak, Eden Prairie’s water resources coordinator. Stormwater from the development drains into nearby Purgatory Creek, which flows into the Minnesota River.

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Lori Haak points out flaws
Eden Prairie Water Resources Coordinator Lori Haak points out flaws in the design of her own neighborhood, where roads and gutters could be improved with significant impacts on a nearby creek that flows into the river.
Judy Griesedieck for MPR News

“We have a direct connection here,” she said.

Chloride is a permanent pollutant, and 67 Minnesota water bodies now have chloride levels higher than state standards set to protect fish and aquatic life. 

The biggest source of chloride pollution is road salt used to melt ice on streets, sidewalks and parking lots. There’s a movement to rethink how those places are built to reduce the need for so much salt.

Eden Prairie is one of several Minnesota cities testing low-salt design. The concept is to plan streets and buildings so ice and melted snow don’t accumulate in places where people walk and drive. Other pilot cities are Bloomington, Minnetonka, Hopkins and Richfield.

Low-salt design is the brainchild of Connie Fortin, a salt reduction expert who's trained more than 20,000 snowplow drivers and property maintenance workers over more than two decades.

"The chloride problem is pretty severe,” Fortin said. “A small amount of chloride, about one teaspoon, pollutes five gallons of water forever. So we’re in trouble."

Person in winter clothing stands in snow and smiles
Connie Fortin, low-salt strategist with Bolton & Menk.
Submitted photo

Two years ago, Bolton & Menk, a Mankato-based architect and engineering firm with offices around the state, acquired Fortin's consulting company. They’ve combined their expertise to develop low-salt design strategies for streets, buildings, parking lots and other places.

Reducing the need for salt makes sense not only to protect the environment, Fortin said. Road salt damages vehicles, pavement and bridges, and it costs state and local governments.

“We spend over $100 million each winter just in Minnesota for our city streets, county roads and state highways, just for the salt purchase,” she said. That doesn’t include deicers used on private parking lots and driveways.

Tim Olson, a water resources engineer with Bolton & Menk, said working with Fortin helped him realize that once salt is in the environment, it’s nearly impossible to remove.

“We need to reduce chloride at the source,” he said. “If we don’t put it on the land, if we don’t put it on the parking lot in the first place, then we’ve removed 100 percent of it from the environment.”

Olson said that required a shift to focusing more on designing for winter — including thinking about where snow gets piled after it's plowed and where it goes after it melts.

Fortin also encourages designers to harness natural elements, such as sun and wind, to speed up “pavement recovery.”

“Basically, whenever anything’s in the shade in the winter, it is slower to recover,” she said. “And it requires more salt, because it’s less safe.”

Two graphics
A graphic shows how planting deciduous instead of coniferous trees along a sidewalk can help reduce shadows and speed up “pavement recovery,” or the melting of snow and ice.
Courtesy of Bolton & Menk

Simple design changes don’t cost a lot, but can make a big difference, Fortin said. Planting deciduous trees instead of coniferous along the south side of a sidewalk can reduce shadows. Designing a building so its parking lot gets full sun helps melt snow and ice quicker.

Another goal is to reduce what Fortin calls “repeat offenders” — those places where snow continually blows across the road or water flows over a sidewalk, requiring frequent salting.

Sidewalk with salt
This sidewalk in Hamel is an example of what low-salt strategist Connie Fortin calls a "repeat offender." Water from melting snow flows over the sidewalk, creating a safety hazard and a need for frequent salting.
Courtesy of Bolton & Menk
Melting snow next to sidewalk
A storm drain in Hamel is placed to catch water from melting snow, preventing it from running onto a nearby sidewalk and reducing the need for deicing salt.
Courtesy of Bolton & Menk

One example is the Eden Prairie Center, built nearly a half century ago — long before low-salt design.

In a normal winter, plows push the snow to the edge of the mall’s parking lot, where the ground slopes steeply down to a city trail and a street below. When the snow melts, the water flows downhill over the trail and street, creating a public safety problem.

A complete redesign of the mall isn’t likely. But Bolton & Menk staff see opportunities for minor fixes that could help — such as creating a depression to store the snow, and a swale or low area to drain the water away from the trail, said landscape architect Joel Odens.

Haak hopes once planners, engineers and landscape architects learn these concepts, designing for less salt will become second nature, both when building new projects and making changes to existing ones.

Spreading a message of smart design might be the best hope to tackle Minnesota’s salty pollution problem, she said.

“We can’t go back,” Haak said. “We need to start as soon as we’re aware of it and really protect our water resources, instead of kicking the can down the road. We know that it’s a problem. We know that there are viable solutions out there.”

Three people posing for a portrait
Eden Prairie Water Resources Coordinator Lori Haak, left, joins landscape architect Joel Odens, center, and limnologist Carolyn Dindorf, both of the firm Bolton & Menk, on a bridge overlooking Purgatory Creek, which eventually flows into the Minnesota River, carrying pollutants from de-icing chemicals.
Judy Griesedieck for MPR News

While the design principles are voluntary right now, there’s a possibility they could become future requirements, as cities struggle to meet limits on the amount of chloride in the stormwater they are permitted to discharge into lakes and rivers.

“I can definitely see in the future that it’s going to be difficult for us to meet chloride standards if we haven't already started thinking about this,” Haak said.

Minnesota might be a logical place for low-salt design to catch hold first. But there's growing interest across the globe, Fortin said. In May, she’s taking her message to an international engineering conference of cold-climate engineers in Anchorage, Alaska.

“This is a problem way beyond Minnesota,” Fortin said.

A few remnants of salt remain on the ground
A few remnants of salt remain on the ground at the Eden Prairie Community Center. Eden Prairie is a pilot city testing and teaching design strategies to reduce the need for road salt.
Judy Griesedieck for MPR News