Collaboration Award

2015 Environmental Leadership Award Recipients
14th Annual Road Salt Symposium
February 5, 2015

Collaboration Award: City of Mankato, City of North Mankato and MnDOT District 7

City of Mankato:  Mary Fralish, Joe Grabianowski, Jim Braunshausen, Dan Fischer, Nick Stevensen, Les Lotton, Andy Ahlman, Dan Baker, Perry Braam, Nate Brand, Ben Brooks, Steve Morrison, Gary Otto, Tom Stier, Charles Thomas, Ryan Thormodson

City of North Mankato:  Brad Swanson, Rhett Morse, Kevin Ling, Craig Shea, Kurt Balbach,  Mark Kopischke, Jim Goebel, John Beaty, Nate Nimps, Dale Seath, Jerry Olson , Cory Kanstrup

MN DOT Dist. 7:  Randy Glaser and District 7 Highway Maintenance Personnel

Collaboration between organizations sharing neighboring areas can help move progressive ideas ahead more efficiently than “going it alone.” The public works crews of City of Mankato and City of North Mankato have been working with and alongside MnDOT’s District 7 to reduce the amount of salt necessary to keep the roads passable in winter. They have partnered with ideas and technology to aid them in using the best practices for saving money and reducing salt. Collaborative efforts include the use of brine and calibration, as well as sharing tips and information on what is being seen during storm events.

The City of Mankato’s Public Works Department plows 432 centerline miles and uses an average of 2,400 tons of salt annually. They have two 1400-gallon brine tanks for pre-treating. The city implemented temperature compensation systems in 2003, to take the guesswork out of knowing how much salt to use. It computes the minimal amount of salt needed to melt the maximum amount of snow and ice by calculating the road temperature and the air temperature along with the speed of the truck.

Annually, the City of Mankato’s snow fighting crew prepares for the season by calibrating all equipment to be confident of how many lbs. /lane mile of salt and gallons/ton of salt brine are being applied. They use 7 – 10 gallons of brine per ton, depending upon the storm event, pavement surface temperatures and other factors. Their equipment allows for application rates down to 90 tons per lane mile.

Prior to each snow event, if surface temps allow, the City of Mankato will pre-treat many of the hills, concrete surfaces, sharp corners, bridges and other areas to decrease the likelihood of the snow and ice bonding to pavement surfaces. This reduces the amount of granular salt required to treat after plowing. They apply their brine when anti-icing at about 40 gallons/lane mile. The City of Mankato averages approximately 41,000 gals. per year in anti-icing. They feel, despite variations in winter severity and additional lane miles, their salt use has dropped at least 50%.
The City of North Mankato also utilizes brine application before a winter storm by anti-icing problem areas. This allows snowplows to remove the majority of the material and reduced reliance of having to melt through it with salt or other chemicals. Consistent planned plowing during events reduces packed snow on surfaces, which in turn reduces the amount of salt needed. The City of North Mankato attributes their reductions in salt to this use of salt brine, the growing use of road speed sensors to adjust application rates, and employee education. Each event is assessed individually for the appropriate techniques to use. (cont.)

The City of Mankato currently obtains brine from MnDOT District 7 and the City of North Mankato intends to implement that approach with the next winter season, to improve efficiency. District 7 first started making and using brine in the mid-1990s. The brine was made in old metal cattle tanks and the truck was constructed with round fiberglass tanks that another district had discarded. Once the operators saw how well brine worked, a bigger system to make brine was needed along with more tanks for the trucks. Every year more tanks were added to trucks. More liquid and less salt was the driving objective.

The Mankato subarea experimented with mixing on-the-fly using herbicide spraying technology, and anti-corrosive additives were tested, along with many other deicing chemicals. The goal was for the most cost-effective method. In 2004-05 Mankato purchased a more automated system capable of fine-tuning brine production and the Windom area built a bigger system to supply the southwest corner of MN in 2006-07.

In 2010, when the Mankato District Headquarters was going to be replaced, the decision was made to invest in a state of the art brine production building capable of supplying not only Mankato’s needs but all of the truck stations, as well as cities and counties in the Mankato area. District 7 has several trucks that they use for anti-icing. The first tanks were smaller, 1000 gallons, and were able to spray three lanes at a time at slow speeds. The next project was MnDOT’s first semi-tanker capable of multi-lane, high speed applications. This tanker holds 6000 gallons.

Thanks to some inventive and determined staff, Mankato District 7 has always been on the cutting edge of brine use, production and dispensing. As with the City of Mankato and the City of North Mankato, District 7 has identified some key techniques to reduce salt use and operate in a cost-effective manner: anti-icing prior to events, using brine to reduce salt loss, using smart application systems, doing proper calibration, and educating operators. Together these three organizations have improved service in the region and continue to support each other in progressive winter maintenance.

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