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University of Minnesota

LEEDing the way

September 1, 2009

The rate control pond across from TCF Bank Stadium.

In the rate control pond, or turlough, across the street from the stadium, storm water flows in and collects, then flows out at a desired rate to ease the pressure on the sewer system.

Photo: Patrick O'Leary

TCF Bank Stadium receives LEED certification for sustainable design

By Rick Moore

When it comes to opinions on the new TCF Bank Stadium, the superlatives already are flying, from the biggest and best locker room in collegiate sports to the biggest and best scoreboard north of Texas.

But the University recently received another nod of approval. On September 17 it was announced that TCF Bank Stadium has gained LEED (Leadership in Energy and Environmental Design) Silver certification from the U.S. Green Building Council, the standard for sustainable, or "green," design.

The stadium becomes the first LEED-certified collegiate or professional football facility in the nation.

From brown to green

Before the University could choose features to make the new stadium green, it had to worry about cleaning up a polluted "brownfield," a task it knew lay ahead when the stadium was approved. An old railroad yard operated by the Chicago Great Western Railway Co. had been at the site, and there had been a creosote operation on the grounds.

"In the late 1800s and early 1900s there had been a wood treatment facility that used creosote to make railroad ties and telephone poles," says Brian Swanson, budget officer in the U's Office of Budget and Finance and a project manager for the stadium. "And there was a lot of remnant material in the ground. We dug it up and properly disposed of it all, which will have a lasting impact on groundwater."

That was a big task, but it could have been worse. "There weren't really any other environmental surprises," he says. "For a former railroad yard, it was actually pretty clean."

A river runs near it

Some of the most impressive—and decidedly green—features of the new stadium center on storm water management.

Previously, when the Huron Boulevard Parking Complex occupied the stadium site, rain washed sand and grit from the asphalt lot through storm sewers and down to the Mississippi River.

With construction of the stadium, the U has built a comprehensive storm water management system for the full 75 acres of the East Gateway District, which encompasses both the stadium and the surrounding biomedical buildings.

The system can handle a 100-year storm event, Swanson says, and it meets the city of Minneapolis requirement that the water leaves the area as clean as it would have been before people settled in the region.

"The U is moving this way in general, so this project fit in to the overall construction programs that the U has," says Swanson. "It's the right thing to do from a stewardship role."

A number of features control both water quality and flow. For starters, a series of bioswales, which are landscaped planting beds with special soil, will remove the suspended solids from the water, Swanson says. "Then some of the water is absorbed right on site for plant use, and the rest of it drains, eventually, to the rate control pond."

There is also the EPIC System by Rehbein Environmental Solutions, comprising three giant troughs that hold three inches of water in sand pans. Above the pans is grass, which is irrigated by the standing water in the pans. (Watch video below.)

The rate control pond (known as a turlough) across the street from the stadium is another intriguing feature. Two 42-inch pipes bring water from the stadium area into the pond, and one 18-inch pipe takes it out. After a rainfall, water will flow into the pond faster than it can flow out and will collect there, then gradually flow out at a desired rate to ease the pressure on the sewer system.

"The pond is the last point of exit before [the water] leaves and goes into the Oak Street tunnel," Swanson says. "By the time the water gets to the pond, it's gone through the quality function, so the pond is strictly for rate control."

Speaking of water, if you were hoping to watch a game in pouring rain and see players sliding all over the field on standing water, you're out of luck. The stadium's FieldTurf is spread atop 24 inches of gravel in three sizes, progressively finer the closer it gets to field level. The net effect of the two feet of gravel is incredible water absorption.

"The idea is that if it just rained and rained and rained and rained, you wouldn't want your field floating," says Swanson. "This [system] can hold two back-to-back 100-year rain events, which would be an awful lot of water. ... There's really good field drainage."

Other shades of green

TCF Bank Stadium has a host of other green features that fall into three broad categories: design, construction, and operation.  They include:

The use of regional materials, defined by LEED as within 500 miles. The steel for the stadium is 90 percent recycled and was fabricated primarily in Minneapolis by LeJeune Steel Co. The concrete seating bowl was produced in Maple Grove by Hanson Structural Precast. Brick came from Gage Brothers in South Dakota. And the concrete portals above the entrances and the cast stone county markers were made by American Artstone in New Ulm.

Green building materials. The University chose paint, carpet, sealants, and adhesives that are low in volatile organic compounds, which can aggravate health problems.

Efficient fixtures. Swanson says that plumbing fixtures are the most efficient the University could get under the Minnesota building code. The stadium also has energy-efficient lighting and elevators.

Recycling construction waste. Mortensen Construction, the general contractor for the stadium, was a big proponent of properly handling construction waste, Swanson says, and during the construction there were separate dumpsters on site for wood, cardboard, and glass. "They achieved incredible recycling rates on their construction waste," he says.

Proximity to mass transit. While the vast majority of fans will likely arrive via car, they will have many alternatives. The stadium has bicycle racks; fans can choose buses (the Transitway will be in use on game days); and eventually, a light rail station may be right across the street.

While the stadium has a good number of green features, some ideas were deemed not to have a cost benefit for a stadium that isn't in constant use—for instance, solar panels, wind generators, and even waterless urinals.

"Certain things about the way the building is used preclude certain kinds of green technology," says Swanson. "We did things on this project that made sense from an institutional perspective and that had a payback." 

Of course, gaining LEED certification is further payback, but that's not what motivated the University, Swanson says.

"The U is moving this way in general, so this project fit in to the overall construction programs that the U has," says Swanson. "It's the right thing to do from a stewardship role."

Plus, he adds, "The building is going to be here for a long time, so we might as well make it as inexpensive to operate as possible." 



Read the release about the stadium's LEED certification.


Watch "TCF Bank: A Green Water Solution" on YouTube

Related Links

TCF Bank Stadium