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Will scrapping Convention Center domes hurt Minneapolis’ Vikings plan?

Replacement of the copper domes could cost $15 million — and affect plans for a downtown Vikings stadium.

The 1.6 million-square-foot Convention Center has four domes; three were built between 1989 and 1991, with a fourth added in 2001.

It’s not a snowy collapse, but the city of Minneapolis faces another dome problem.

An unfortunate design in the Minneapolis Convention Center’s copper domes has blown what could be a $15 million hole in the building’s capital budget. And that could affect plans for another edifice, a downtown Vikings stadium.

Mayor R.T. Rybak’s latest Vikings stadium plan relies on “excess” revenues from taxes meant for the Convention Center. A mayoral spokesman insists the roof problem won’t affect the stadium plan, even though it may claim some of those taxes. City Council skeptics aren’t as confident, and the building manager calls still-unclear demands on the taxes a “concern.”

If nothing else, the costly replacement — potentially costing more than the city charter’s $10 million stadium-subsidy limit — shows how aging buildings could trip up new ones.

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The ‘ice cube tray’
The 1.6 million-square-foot Convention Center has four domes; three were built between 1989 and 1991, with a fourth added in 2001.

The swirling ridges and diamond-shaped panels are undeniably artistic. However, if you’d hoped to live long enough to see the copper turn as green as the Statue of Liberty’s skin, it is not meant to be.

Convention Center executive director Jeff Johnson likens the ridged design to an “ice cube tray” that holds water. Twenty winters’ worth of expanding and contraction has opened many leaks, predominantly between the older domes’ copper plates.

Each dome has a sealant underlayment. The sealant is like tarpaper, and after 20 summers, has melted down the curved surfaces. Result: the Convention Center spends $250,000 a year chasing leaks, Johnson says.

The tarpaper is the real problem, but once you tear the copper off to get at it “you can really cannot put the old copper back on,” he notes. “It’s like a jigsaw puzzle.”

Johnson is currently readying bid specifications and expects to present a package to the Council this spring. Without firm numbers, Johnson estimates replacement at “$5 million to $15 million; probably the higher end of the range” if a more modern copper system replaces it.

To offset some of that cost, Johnson told Gary Schiff in November that the city could sell the old copper, though it likely wouldn’t come close to paying the bill.

Bad planning?
Despite the design flaws, Johnson says the copper roof lasted 22 years, past its 10-year warranty. It shouldn’t be surprising that that the system is nearing the end of its useful life, he adds: “Call the Mall of America and see if they get roof leaks. Roofs deteriorate.”

Still, dome replacement is not in the building’s current 15-year capital plan. “A functional roof is super-important, so we’ll be looking at repurposing money, bonding, looking at all sorts of ways to pay for it,” Johnson notes.

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Bonding — another word for borrowing — might sap money from the most recent Vikings stadium plan, if paid off with the same taxes that fund Convention Center improvements.

Unfortunately for both the Convention Center and the stadium plan, there are no excess taxes until 2021. The latest Vikings plan calls for the state to front Minneapolis the cash; when the excess materializes, the city will pay $300 million-plus through 2045.

According to finance projections released last week, the Convention Center’s capital account is slated to get $7.1 million this year, and between $9 million and $18 million per year from 2014 to 2045, totalling $365 million.

If a $15 million expenditure is accounted for somewhere in that $365 million plan, stadium financing might not be hurt. But during last week’s stadium hearing, Schiff pointedly contrasted a new Vikings stadium with needing to sell copper for scrap.

Mayor’s office: no effect on stadium plan
Rybak spokesman John Stiles pegs the dome-replacement cost at $5 million to $10 million, well below Johnson’s top-end estimate. He acknowledges that Minneapolis “will most likely bond for a significant share of the project, with borrowing paid back over time through Convention Center/hospitality taxes.”

Still, Stiles argues the spending “won’t be a material factor at all in the existing stadium plan. With or without a stadium, we will annually revist all expenditure needs of the Convention Center and Target Center, and develop plans to accommodate them, including whether to finance capital improvements or use existing cash.”

That’s what worries another Council opponent, Elizabeth Glidden. Despite Stiles’ confidence, Glidden says that because the same taxes would fund a Vikings stadium, Target Center and Convention Center, the city buildings could come last.

“Do you think the state will let Target Center and Convention Center obligations come before the Vikings stadium?” asks Glidden, who has long chaired the council committee that lobbies the legislature. “They’re all money holes — we’ve seen that. What happens if there’s a year when the sales tax revenue doesn’t come through?”

Although Rybak touts the property-tax savings from moving Target Center onto the Convention Center sales tax, Glidden says surprises like a bad copper roof or a bad downtown economy anytime in the next 30 years could put taxpayers right back on the hook, with the sales tax significantly obligated to Wilf Field through 2045.

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A plastic cap?
Copper isn’t the only option for the domes. Johnson thinks there’s a cheaper one: “Recycled plastic. PVC, actually.”

That’s right: the Convention Center could soon sport plastic bubbles. The plastic — which would essentially be a sealed cap with no need for an underlayment — might be had at the $5 million end of the range. That price, amid grand plans elsewhere, might be hard to turn down.

Still, wouldn’t protruding PVC look a little … cheesy?

Johnson says he intends to replace the domes with “the same look and same functionality we currently have. My expectation is that a normal person would not know the difference between today and whatever we do.”

The proof may already be visible. “There’s a test section up there right now,” Johnson notes. “I don’t think anybody could ever tell.”

Let’s hope that’s still true 20 years from now.