written by Jamie Fisher, Wisconsin Department of Natural Resources
In 2008, the Polk County Highway Department was thinking of ways to cut down on costs. One particular cost came to mind – the salt brine used as a pre-wetter on icy winter roads before applying dry salt.
“We were looking at ways to save on winter maintenance and did not have our own salt brine maker,” said Emil “Moe” Norby, technical support manager with the Polk County Highway Department. “We know the dairy used salt water in the making of their cheese.”
F&A Dairy in Dresser, Wis., uses salt brine, a clear solution of water and around 25 perrcent salt, in the cheese making process and produces 3,000 to 5,000 gallons of the liquid per week. The two groups formed a partnership for the highway department to use the dairy’s salt brine, making for creative reuse of what would otherwise be a waste product – the dairy’s leftover brine is normally sent through a wastewater treatment plant. With this new partnership in place, F&A Dairy simply filters the brine to remove any whey solids and sends it on to the highway department.
During the 2008-09 winter season, Polk County ran test routes using salt brine samples from the dairy as a pre-wetter on county roads. It found that applying the brine before applying dry salt cleared the roads more quickly and allowed the department to use less salt overall.
“Once the material is wet, you can then begin to turn down the material rate because the salt is working faster with pre-wetting,” Norby said. “Pre-wetting also helps the material stick to the roadway.”
Using salt brine offers other advantages as well. As an environmental benefit, reducing the amount of dry salt that bounces off the road also keeps it from entering area watersheds. The dairy’s brine also works to a colder road temperature than traditional brine. The highway department has seen significant cost savings from using less salt, and the only cost to using the dairy’s brine is trucking the liquid to the highway department’s storage tanks.
Since that first test year, Polk County has received salt brine from F&A Dairy every winter. Norby reported that the highway department used almost 40,000 gallons of brine provided by the dairy in the 2011-2012 season, even with a light winter that required minimal road maintenance.
Three other municipalities reuse salt brine from F&A Dairy in their winter road work, and Burnett Dairy Cooperative in Burnett County has formed similar partnerships. Distribution by these two dairies in 2011-2012 resulted in the reuse of more than 119,000 gallons of salt brine.