Wacker Neuson E3000 Ground Heaters in Deep Thaw in Duluth

Kraus-Anderson Construction Company saved between $315,000 to $365,000 by using 3 Wacker Neuson E3000 Ground Heaters units rather than twice as many propane heaters for a ground thawing project in Duluth. In addition, the E3000 made it much easier for the crews continue the overhead structure work, since they didn’t have to work around large, bulky tents.  

Maintenance Facility
Extremely low temperatures, early fall freezes and late spring thaws are just a few of the challenges facing contractors working through the harsh winter months in northern Minnesota. These extremes can leave several feet of ground frost for contractors to thaw before continuing with construction projects.
Just ask Kraus-Anderson Construction Company how tough it can be to thaw the ground, even in the late spring. When the North Division of the Minneapolis-based firm was constructing a $26 million maintenance facility for Northwest Airlines in Duluth, the winter weather left Kraus-Anderson’s crews with 5 to 7 feet of frost to thaw in May.

The hangar, which covers 186,000 square feet of ground, services mid-size jets brought in from around the nation. While Project Superintendent Dave Stolts planned to pour the concrete slab for the building in the winter, the frozen ground shifted the crew to "plan B" - completing the overhead structure while working off the frozen ground rather than a concrete slab.

The overhead work complicated frost removal even more by blocking out the warmth of the sun and insulating the frozen ground. In addition, the prior wet fall created extreme frost conditions. "We weren’t fighting frost," Stolts said. "We were fighting ice." (According to Wacker Neuson Climate Technology this is true in all thawing applications. Ground doesn’t freeze. Water in the ground freezes and turns to ice, making it nearly impossible to excavate.)

In early March, Kraus-Anderson attempted to thaw the ground inside the facility by constructing tents of poly to contain the heat and using approximately six propane heaters in sizes up to 2 million BTU. Burning nearly $30,000 of fuel and removing only 4 feet of frost in two weeks in a 10,000 square foot area, Stolts said the propane heaters were slow and ineffective at penetrating the deep frost.
In May, Kraus-Anderson signed a contract to rent three Wacker Neuson E3000 Ground Heaters through early June. Each heater was able to remove 5 feet of frost from a 6,000 square foot area for a total of 18,000 square feet per week.

"We were able to cut our thawing time by 2 weeks," Stolts said. Kraus-Anderson estimated that it would have taken 3 months and $350,000 to $400,000 worth of propane fuel to accomplish what was done in 5 weeks with less than $35,000 worth of rental expense and fuel for 3 Wacker Neuson heaters.
Stolts said the E3000 heaters also provided greater accessibility by allowing the crew to work in the area without the cumbersome hassles of plastic tents. In addition, the units offered greater efficiency over propane heaters, as well as a better way to meet short deadlines. "Every bit of fuel we purchased was going straight into thawing the ground," Stolts said. "We didn’t heat the air around it and waste energy."

Stolts added that the E3000 heaters could impact the way a company such as Kraus-Anderson bids jobs by giving them a scheduling advantage. "A schedule is everything," he said. "On projects like this, if we didn’t make our schedule, we’d pay a $10,000 fine per day." In addition, the Wacker Neuson heaters would give them a bargaining tool in the actual bidding process. "If we tell an owner we can complete a job in 12 months and another contractor submits a bid for the same amount of money, saying they can finish in 14 months, which one do you think they will choose?"