Photos courtesy Washington County
Washington County in Minnesota recently shared that its snowplows use a derivative of sugar beets to help manage ice on the county’s roads.
The county points to benefits such as a 79 percent reduction in corrosion compared to other materials, long-lasting de-icing effects which slows down the refreeze rate, and environmental benefits due to the fact it is “99% biodegradable in 28 days.”
“Did you know that our plows are environmentally friendly? They have been spreading a beet derivative on county roads since 2018,” the county recently said on social media. “It’s an organic based, corrosion inhibited, liquid deicer and is made locally in St. Paul. It’s not beet juice, but is made up of processed beet molasses and a lot of sugar.”
The material is an alternative to salt, which has been found in recent years to pollute nearby lakes and rivers when it runs off roads. Beet molasses is also less corrosive, meaning it can extend the life of road surfaces and cause less rust on vehicles that drive on the roads.
The beet material is usually mixed with a liquid salt brine, making the salt last longer and reducing the amount needed. The sticky sugars not only break down ice, but the substance clings to road surfaces, allowing less salt to be applied.
Salt water worries
The Minnesota Pollution Control Agency has raised concerns about road salt and its effects on the state’s water for the past several years. Chloride can leach into both underground aquifers that supply drinking water, as well as nearby lakes and streams. In surface water, it can kill or otherwise harm plants and animals, disrupt lake chemistry, and make soil and sediment less absorbent.
The MPCA says it takes only one teaspoon of road salt to permanently pollute five gallons of water.
“An estimated 365,000 tons of road salt is applied in just the Twin Cities metro area each year,” the agency says. “A study by the University of Minnesota found that about 78 percent of salt applied in the Twin Cities for winter maintenance is either transported to groundwater or remains in the local lakes and wetlands.”
It’s estimated that every ton of road salt causes $803 to $3,341 worth of damage to roads and bridges. Based on the Twin Cities average use, that’s $293 million to $1.2 billion in damages — each year.
One concern about beet-based substances it that they are full of sugar and other organic material. This can consume more oxygen in water and cause increased levels of nutrients and heavy metals. There has been no evidence of that being a significant problem yet.
Creeping contamination
The MPCA lists about 50 lakes and streams across Minnesota that are currently “impaired” by salt, with many more headed that way. The problem is concentrated in the Twin Cities metro area, where the greatest number of people, cars, and roads exist. Almost a third of wells in the metro area have chloride levels about drinking water guidelines.
In the St. Croix River watershed, there’s just a two-mile stretch of a creek in Forest Lake that is impaired for chloride.
In the decades ahead, as the Twin Cities area, with its high number of residents and commuters, expands, preventing salt pollution will be important.
Washington County currently plows nearly 270 miles of highways. It is also home to several St. Croix River tributaries, including trout streams Valley Creek and Brown’s Creek. Neither has been found to be impaired by salt yet.
With efforts like the beet-based brine, they could stay that way.
Resources
- Chloride 101 – MPCA
- Environmental impacts of road salt and other de-icing chemicals – Minnesota Stormwater Manual
- Other impacts of road salt use – Minnesota Stormwater Manual
- Road salt, smart salting and winter maintenance – Minnesota Stormwater Manual
- Smart Salting training – MPCA
- Chloride Free Snow and Ice Control Material (PDF) – MnDOT