Want to Reduce Road Salt Impacts on Ecosystems and Infrastructure? Just Add Water.

The above picture shows CFL assistant professor Hilary Dugan and a giant pile of rock salt. It is so much salt. How much? Well, this particular pile belongs to the Jefferson County Highway Department and it’s not uncommon for them to dump literal tons of salt onto county roads and Interstate 94 during an extended winter storm.

While all of this salt helps keep roads clear and safe, it comes with a big cost. It rusts out our cars and corrodes concrete bridges and, as Hilary’s research has shown, it is salting our freshwater ecosystems.

On Tuesday, Hilary and I got to take a tour of the Jefferson County Highway Department’s winter operations. Hilary was invited to give a talk about her research but, while they had us, the folks at Jefferson County wanted to show us something cool – there is a far better way to salt roads.

The secret? Just add water. 

Here’s a cool slideshow of our tour to help explain.

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One of the problems with traditional road salt is a lot of it ends up anywhere other than the road. As it falls from the back of a truck, it bounces away or is pushed to the side by plows or blows into the median. 

Another issue is that rock salt takes a while to work. It does little good in solid form to melt ice or keep a road from freezing. In fact, it can take it two hours to mix with moisture on the road and “melt” into a brine solution, which is when it really gets to work. 

By mixing the rock salt with water at the front end of the process, road crews create the salt brine they’re after in the first place and can spray it directly on the road in an even coat, eliminating both the waste of all that rock salt bouncing away and the wait time for the stuff to start working.

It also eliminates tons and tons of salt from a road crew’s winter budget.

Not too long ago, it wasn’t unusual for a truck like this to dump more than a half-ton of salt per mile. 

As one snow plow driver told me, when he first started driving, it was common practice for him to put down 800 pounds of rock salt per lane mile (in other words, a two-lane county road received 1,600 pounds of salt per mile). There were times, he said, when they would put down 100 tons of salt for one storm. Now, thanks to best practices in salting and the switch to brine, that number is one-fifth of what it once was.

The Jefferson County Highway Department says their switch to brine has already reduced salt use by 30 to 40% and estimates that, this winter, salt brine alone has been enough to deal with more than 60% of storms. Of course icy events like our current wintry mix mean that all ice-melting tools in the toolbox get deployed (even rock salt) but, over the course of a season, that is a lot less salt they have to buy, a lot less salt damaging cars and bridges and other transportation infrastructure and (for the issue closest to this particular blog’s heart) a lot less salt ending up in our lakes, rivers, streams and wetlands.

What’s more, Wisconsin’s Department of Transportation recently purchased 15 more salt brine making units to spread around to other counties. 

As road maintenance evolves, this move to brine is good news. Salt in our freshwater is an issue we just might be able to tackle, Hilary says.

“We know the sources and it’s not a chemical that stays in the landscape, it flushes out. It’s gratifying to be working on an environmental issue that we can solve in our lifetime.”

For more on how you can be a “salt smart” citizen, check out the resources over at the Wisconsin Salt Wise website.

4 thoughts on “Want to Reduce Road Salt Impacts on Ecosystems and Infrastructure? Just Add Water.”

  1. I was sorry to not be able to attend your science on tap presentation yesterday evening. I did find reading your brine deicing information very interesting and wanted to share that in addition to brine being a more effective deicer there is potential for other environmental benefits. I work for the Dept of natural resources’ waste management program and we issue exemptions to several cheese processors, a vegetable cannery and a soy sauce manufacturer allowing them the provide their waste brine for road deicer rather then disposing of it as a waste water. This lessens impacts both on water treatment and on buying and creating brine materials. If you are interested in the communities using waste brine for road deicer please feel free to contact me.

    1. Thanks, Casey and sorry we missed you. That’s really interesting, I’ll take a look and reach out it we want to do a follow up blog. In the meantime, you can find the video of the talk on our Science on Tap-Madison Facebook page!

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