March 2023Vol. 31, No. 1

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Reducing road salt pollution using winter-smart design

Vehicles driving on road during snowstorm

Photo: Adobe Stock

Efforts to reduce the impact of road salt on Minnesota’s environment, infrastructure, and public health have historically focused on low-salt maintenance practices. Connie Fortin, a presenter at the 2022 CTS Research Conference, proposed an even more proactive measure: Design low-salt strategies directly into the infrastructure itself.

“Basically, we use a lot of salt/chloride,” said Fortin, senior project manager at Bolton & Menk. “We put it on our roads and we put it in our water softeners, we put it in our farm fields, but [the chlorides] still end up in our water.”

EPA standards put the safe threshold for chloride in water at 230 mg/L, above which the water becomes toxic to aquatic life and undrinkable for humans. According to the MPCA, salt is permanent once in the environment—therefore a cumulative problem—and it can cause significant damage to infrastructure and vehicles.

“We are not going to have good water to drink unless we design the future for low salt,” Fortin said.

Fortin’s approach to the problem draws from her background as an environmental consultant. She spent 25 years designing and implementing low-salt maintenance programs for snowplow drivers and other maintenance personnel. From this experience, she learned how infrastructure design and maintenance needs sometimes conflict.

“When I teach people that are out there dealing with the snow and ice, they inevitably complain about the design of the road—the bridge, the ramp, the parking lot,” Fortin said. “Engineering, research, and permits on the city, county, and state levels tend to be very stormwater-oriented, rather than winter, snow, and ice-oriented. And the problem is winter performs differently than summer. If we don’t design for winter, then we find ourselves at a disadvantage.”

When Fortin’s company was acquired by Bolton & Menk in early 2022, she decided to start pushing for infrastructure designs that were more salt-conscious.

By collaborating with the company’s engineers, she produced a list of broad “basic winter design principles” for low-salt design that could be considered when working on an infrastructure project:

  • Keep angle of the sun in mind to ensure it reaches and melts critical icy patches.
  • Consider direction of prevailing winter wind to prevent drifting snow and “blow ice” (ice formed when light snow is blown back on otherwise clear roads).
  • Consider directional flow of meltwater and mitigate refreezing across roads, parking lots, etc.
  • Ensure proper salt storage to prevent runoff.
  • Consider pavement alternatives such as permeable pavements, which drain meltwater more efficiently and require less salt.

“These considerations are intended to be low-cost measures that don’t take much extra effort to include into designs,” Fortin said, “and they have the potential to save money on salt maintenance, usage, and salt remediation.”

Moving forward, Bolton & Menk will continue integrating low-salt solutions into its design and planning work. The firm helped design a transportation plan for a Greater Minnesota county, with special emphasis placed on identifying winter performance issues.

“We’re hoping to start a movement,” Fortin said. “Not just in Minnesota, but across all cold climates. Because it’s a problem everywhere.”

—Sophie Koch, LTAP freelancer

Minnesota Statewide Chloride Management Plan

Minnesota is the first state in the country to develop a statewide chloride management plan. The plan lays out state salt reduction goals and provides resources and strategies that different stakeholders (such as municipalities, watershed districts, and winter maintenance professionals) can reference.

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