Looking up at the roof of Key Arena in Seattle on Tuesday as construction continues below to build a new sports and entertainment venue. (GeekWire Photo / Kevin Lisota)

Before a puck ever drops for professional hockey in Seattle, the ground had to drop out from below Key Arena in order to preserve the historic building’s roofline. That stipulation presented engineering and construction workers with a 44-million-pound renovation challenge, and Tuesday they showed off their progress in taking on the task.

The existing roof, originally designed by architect Paul Thiry for the 1962 Seattle World’s Fair, has been detached from 20 original concrete Y-columns and four gigantic buttresses that previously supported it. It’s now “floating” above the construction site, supported by 72 temporary steel columns, cross-beams and a steel reinforcement structure called a “kickstand.”

Workers need to remove 600,000 cubic yards of dirt during the excavation of the arena bowl, which will put the new bowl 53 feet below ground and make the venue almost double the size of the Key.

Ken Johnsen, executive vice president of construction for Oak View Group, the firm leading the project, said they were three quarters of the way through excavation, which should be completed in February.

“2019 was [about] going down, 2020 is going up,” Johnsen said. “The really good news is we have bottomed out on the north part of the project and have started to pour foundations and come back up.”

The work of concrete footings at Key Arena has been temporarily replaced by steel supports. (GeekWire Photo / Kevin Lisota)

Johnsen said the roof is practically hovering like a “hovercraft from Star Wars,” waiting for the new building — “the best arena in the country” — to rise up below it and reconnect.

The suspended roof has sensors on it, and is has been designed to withhold wind and seismic activity. Johnsen said there are challenges every day on the unique project.

“The roof … I would be exaggerating if I didn’t say there were a few times people tilted their heads and said, ‘How’d we do that?'” Johnsen said.

(GeekWire Photo / Kevin Lisota)
(GeekWire Photo / Kevin Lisota)

Key Arena was the onetime home of the city’s departed NBA franchise, the Seattle SuperSonics, as well as the home court for the WNBA’s Seattle Storm.

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The location in the lower Queen Anne neighborhood is just blocks from Seattle’s major South Lake Union tech hub — home to offices for thousands of workers at Amazon, Google, Facebook, Apple and more

Sports industry veteran Tim Leiweke leads Oak View Group, which won approval from the Seattle City Council in 2017 to build the revamped arena. An original price tag of $660 million has pushed past $900 million, according to The Seattle Times.

The privately financed project is scheduled to be completed in summer 2021 in time for the inaugural season of NHL hockey in Seattle.

A rendering of the new arena at Seattle Center. (Oak View Group Image)
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