MINNEAPOLIS -- They played two World Series in the Hubert H. Humphrey Metrodome, and the same number of Final Fours. Baseball's All-Star Game, the Super Bowl, Pink Floyd and Paul McCartney all made appearances as well. And yet, from a national perspective, the dominant memory might well have originated on Dec. 12, 2010 -- when the roof collapsed a day before a Minnesota Vikings game.
The Teflon-coated roof was one of many engineering quirks that gave the Metrodome a retro-futuristic feel that was equal parts Jetsons and Lite-Brite. My personal favorite was the strict rule against opening any set of double doors at the same time, a fail-safe against altering the air pressure setting that maintained the roof's shape.
That rule was one of many improvised plans that stadium engineers developed and followed to maintain a building that will host its final event Sunday. And it's why Steve Maki and six colleagues found themselves on the roof with fire hoses and a steam connection in the hours before the 2010 collapse.
We'll get back to that incredible instance of homespun maintenance in a moment. First, it's important to know a few facts about the roof.
The original design called for 20 fans of 90 horsepower apiece to maintain inflation from their position at the top of the stadium. Because it was used in a region that receives about 50 inches of snow per year, a system was installed to melt snow accumulation on the roof by shooting hot air between two layers of fabric on the surface.
The roof, however, deflated or ripped three times between 1981 and 1983. According to Maki, who was hired as the Metrodome's top engineer in 1985, the holes providing ventilation were too small to allow in enough hot air to melt snow.
Through trial and error, engineers developed a do-it-yourself routine for removing snow accumulation from the roof. First, they would crank the temperature in the building above 80 degrees. Usually, the rising heat would penetrate the roof and initiate melting. But for more significant occasions, they came up with an emergency plan that seemed stolen from a Rube Goldberg diagram.
Water connections were installed where the concrete structure met the perimeter of the roof. Later, a steam line was added. Fire hoses also were purchased.
If 80 degree heat rising didn't melt the snow, stadium workers would clamber to the roof and connect the hoses to water and steam outputs. Standing on eight-inch cable lines, 150 feet above ground, they pointed hoses and manually melted snow with hot water.
Yes, that's how the Metrodome hosted 300 events a year for more than a quarter century. And it's how it came to be that Maki and six colleagues found themselves on the roof at 10 a.m. Dec. 11, 2010, amid what turned out to be the fifth-largest snowstorm in Minnesota history.
A total of 17.1 inches would fall over a 24-hour period, accompanied by 25 mph winds and sub-zero temperatures. Dressed in snowsuits and ski goggles, Maki and his crew spent nearly eight hours on the Metrodome roof spraying water trying to make a dent in the accumulation.
In 2010, American bioengineers created the first "self-replicating, synthetically designed life." British researchers developed an embryo using DNA from three parents. Astronomers discovered evidence that there could be water on the moon. But in Minnesota, there proved to be no way to prevent snow from collapsing the fabric roof on an NFL stadium.
"We just couldn't make any headway," Maki said. "That storm was a rare occasion of a lot of snow, winds that were really strong and falling temperatures. It was so cold that by the time the water reached the snow, it wasn't hot anymore. Nothing was melting."
Wind gusts were the biggest danger. Fearing his crew could be blown off the roof, Maki pulled them down at 5:30 p.m. The decision meant a catastrophic roof collapse, but Maki said: "The safety of our guys came first, obviously. We had to do it."
Smirk all you want about an NFL stadium kept online by such low-tech methods. (I'm not aware of any use of duct tape, spackle or bubble gum.) If you ask me, it was an engineering miracle that Maki and his group managed to keep the deficient roof inflated for 27 consecutive years.
This was a building erected for $55 million.
With design flaws that were immediately apparent.
Whose tenants began clamoring to get out less than 15 years after it opened.
The Metrodome's legacy? To me, it's that it has a legacy at all. How this building made it 32 years is, well, an engineering feat for the ages.