WATCH: Like 'butter on your pan': City crews mastering the science of salt brine treatment for roads
FARGO — It may seem counterintuitive to spray any kind of liquid outdoors during frigid North Dakota and Minnesota winters, but city crews here do it in the name of safer roads.
The cities of Fargo, Moorhead and West Fargo use salt brine as one weapon in their winter weather arsenals.
Fargo Public Works Director Ben Dow said the liquid keeps snow from bonding to pavement and can help fight frost on bridge decks and underpasses.
“It’s like putting butter on your pan when making eggs so the eggs won’t stick,” Dow said.
To cut back on use of concentrated rock salt, the city has been applying some form of salt brine for more than 15 years and making its own for the last 10 years.
The practice of spraying it on the roads before a plowable snowfall is known as “pretreating.” But the conditions under which it can be used are specific — spray it in the wrong kind of weather and it could make roads more slippery.
The Fargo crews have come to know the science well enough that employees have been asked to help educate other cities.
“We have a lot of smart people,” Dow said.
Prevent ice, not make it
The brine Fargo makes is 23 percent salt, about 10 percent carbohydrate product, and the remainder is water, Dow said. The carbohydrate is a corn-syrup variety — a proprietary mix called AMP, made by EnviroTech Services.
The city of Moorhead buys and uses Fargo’s salt brine on its roads, Dow said, while West Fargo uses a brine that employs beet juice as the carbohydrate.
Both salt and carbohydrate allow the brine to be used at lower temperatures, he said.
Fargo Public Works Supervisor Lee Anderson said they monitor weather conditions carefully to apply the brine at the right time. Pavement temperature is most important in ensuring the liquid doesn’t freeze.
“We have to guard against that. We don’t want to go make ice, we try to prevent ice,” Anderson said.
When a plowable snow is in the forecast, the brine-spraying trucks are deployed, usually the night before.
Anderson said snow will always make roads slippery, but the brine keeps it from sticking to them. After plows come through, crews are able to put down much less salt.
The city’s three trucks spray 54 gallons of brine per lane mile. Dow said it takes about 10 hours to hit all of Fargo’s main arterial roads, with a total of 25,000 gallons sprayed before a big snowfall.
The brine is used more often for frost prevention on smaller areas, such as bridge decks and the 12th Avenue North viaduct, he said.
'Apples and oranges'
The city has come a long way from the early days of using salt brine to reclaim pavement after a snowstorm. “It’s apples and oranges,” Anderson said.
Former Fargo mayor, the late Dennis Walaker, was skeptical of the product at first, Anderson said, but became a supporter over time.
Walaker led fights against the two largest floods in Fargo’s history, as public works director in 1997 and as mayor in 2009. The winter that preceded the 1997 flood was the snowiest in the recorded history of Fargo-Moorhead, with a total of 117 inches.
Dow recalled that without any sort of pretreatment, residents drove on slick, snow-compacted roads for most of that winter.
Now, following a pretreatment and about one or two days after streets have been plowed, any compacted snow “kind of breaks up” and moves to the side, he said.
Environmental, corrosion concerns
Using 23 percent salt in the brine versus 100 percent rock salt is cheaper and reduces impacts on waterways, Dow said.
The U.S. Environmental Protection Agency monitors amounts of salt and sand that cities put down. " We’re trying to be proactive and be ahead of the game, so we don’t have to come into restrictions," Dow said.
Then, there’s the matter of the impact on vehicles.
A 2017 AAA survey found U.S. drivers paid about $3 billion annually for rust repairs caused by chemicals used to deal with ice on roads. The average cost of a repair was $490, according to the survey.
"There can be a significant cost if people aren't taking good care of their vehicles and washing them frequently," AAA spokesman Gene LaDoucer said.
Despite these costs, LaDoucer said it's better for a road crew to use anti-icing chemicals to prevent ice than for a driver to crash because of the ice. "I'd much rather wash my car more frequently than have to take it into a body shop," he said.
Because anti-icing chemicals can collect in the undercarriage of a car and damage auto parts, LaDoucer said, it's best to try to avoid the chemicals when they're still wet on the road.
AAA recommends that drivers regularly wash their vehicles, apply wax to protect the finish and give the undercarriage a spring cleaning so any residual chemicals don't continue to cause corrosion.