Snow is no joke in Minnesota, especially when it’s thick and heavy. That will be especially true for the new Vikings stadium and the massive roof that will cover its 1.75 million square feet of seating and playing space.
Uponor North America, with an Apple Valley factory, has come up with a solution that involves a snow melt system that captures snow in huge basins and melts it.
“This is a unique project, the first of its kind at least in North America, as far as we know,” said Joe Grubesic, Uponor’s director of sales for the Midwest.
Vikings fans and others likely remember how snow buildup caused the former Metrodome to collapse in December 2010. The skies dropped 17 inches of snow the day before the Vikings were scheduled to play the New York Giants. Three huge fabric panels tore in the middle of the night under the stress of weight and high winds, and the Metrodome was out of commission for months.
The new stadium roof is pitched to allow snow to slide off, Grubesic said. It will slide into huge catch basins built along the outside perimeter of the roof to keep snow or ice from falling on pedestrians just outside the stadium.
The catch basins — with a total area of about 58,000 square feet — are designed to blend into the stadium’s exterior, he said, and range from 5 feet wide to 40 feet wide, depending on their location.
“Functionally, it’s not a gutter, but the catch basins go all along the perimeter of the roof like a gutter does, even though it doesn’t look like one,” Grubesic said.
The catch basins will contain mats of embedded ¾-inch diameter plastic pipe — 70,000 feet in all — that contain a mix of water that can be heated to melt the snow, as well as glycol to prevent freezing.
The Helsinki, Finland-based Uponor makes the cross-linked polyethylene pipe at its Apple Valley factory, where most of the company’s 500 North American employees work. It uses the tubing in radiant floor heating, snow and ice melting, and other piping and plumbing applications in commercial and residential buildings.
Grubesic said the design for the new stadium — officially called the Minnesota Multi-Purpose Stadium — took into account that snow can accumulate at different depths and melt at different rates, depending on what side of the roof it falls on, wind conditions, the angle of the sun and other factors.
Because of that, he said, the system has six different zones that operate independently and can run for longer or shorter periods of time as needed.
Each zone has its own closed loop of pipe. A boiler heats the water and circulates it through each system, Grubesic said.
“Instead of allowing the snow to accumulate and then melting it, snow melt systems are typically turned on ahead of projected snowfalls, so that as the snow is falling, it’s not necessarily accumulating at all on the roof of the stadium,” he said.
The resulting water is collected by multiple drains located within each basin, he said.
Besides manufacturing the pipe, Uponor’s design services department collaborated on the snow melt system with St. Paul-based Harris Mechanical, the stadium project’s mechanical contractor. Harris will install the system.
Uponor has also contributed snow melting products to NFL open-air stadiums in Chicago and, most recently, at Lambeau Field in Green Bay, Wis.
However, in those cases, pipes were installed under the playing fields as part of turf conditioning projects.
“It’s the same concept — running hot water through pipes — in those cases to keep the playing surface dry and free of snow and moisture,” Grubesic said.
The Vikings project is unusual because the system is elevated, he said, with catch basins 100 to 125 feet above ground.
He said the snow melt system components will be delivered to the stadium site at the end of this month and installation will begin shortly thereafter.