The Mitchell Park Domes remained closed after an engineering study Monday concluded refurbishing them could cost between $65 million and $75 million. Credit: Rick Wood

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An engineering study of the Mitchell Park Domes has concluded the cost of refurbishing the deteriorating south side landmark could range between $65 million and $75 million, County Executive Chris Abele said Monday.

The beehive-shaped structure at 524 S. Layton Blvd. would have to be entirely reconstructed if officials decided to move ahead with repairs of the conservatory, which has attracted millions of visitors over the years.

The Domes were closed over the weekend to protect the public and employees from potentially falling debris after officials closed one of the three glass structures that houses desert plants on Jan. 28.

All three will remain closed until temporary repairs can be made. The county has already started notifying wedding parties and representatives for other scheduled events that the venue, for now, won't be open, and is trying to find alternate accommodations.

At a news conference at his office, Abele said a short-term, labor-intensive fix would begin soon — perhaps in two weeks — to wrap thousands of spots to prevent more concrete from falling.

He estimated the cost as "in the big six figures," but he could not say when those repairs would be finished. The county will have a better idea in the next few weeks, he said.

The wrapped areas could last as long as "double digits," referring to years, Abele said, but the repairs would not be a long-term solution.

The decision to completely refurbish the venerable structure isn't his alone but will require the input of Milwaukee County Supervisors and the public.

He declined to say what his personal preference would be.

The cost estimates to replace the Domes were provided by Graef USA, an engineering consulting firm.

"That's a lot of money for the county," Abele said. "It's not my money. It's your money.

"We will do everything we can in the short term to get, as fast as we can, to the safe usability of the Domes.

"And I think it's important, though, going forward that we give ourself the opportunity — 50 years after the creation of these domes — to as a community ask ourselves, 'is this what we want to do going forward, replicate the domes again?'"

Political overtones

The Domes are sure to take on a political context in the election for county executive.

Sen. Chris Larson (D-Milwaukee), who is challenging Abele for the county's top elective post, held a news conference in front of the shuttered Domes two hours before Abele met with the media. Larson said he wanted to make sure it would remain open for future generations.

The problems have been known for years and he said Abele has done little to address deferred maintenance at the Domes and throughout the county parks system.

"I want more transparency," Larson said. "We have been putting off decisions too long and we can't do that anymore."

In response, Abele said the Domes' maintenance issues have been known for years and that since 2013 he supported $500,000 in interim repairs and assessment.

Last week, frustrated supervisors who had not immediately learned that one of the dome structures had been closed, called in Parks Director John Dargle Jr. to the Finance, Personnel and Audit Committee to seek more details on the state of the landmark.

In a meeting with reporters and editors of the Milwaukee Journal Sentinel, Mayor Tom Barrett also weighed in.

"The Domes are very special to anybody who's been in Milwaukee for any period of time," Barrett said. "I wouldn't want to be the one to tear down the Domes."

Abele said engineers and county staff had considered using netting to catch falling debris.

More recently, the idea of wrapping potential problem areas has gained support, he said.

It would require meticulous work with crews using a nylon-type product to wrap concrete at thousands of individual nodes, said Greg High, the county's director of architecture, engineering and environmental services.

He said each of the three domes is constructed with triangles of glass, steel and concrete. Workers would wrap the concrete at each point where the triangles meet.

The culprit: Moisture, humidity, changes in temperature — and age.

The Domes were constructed in stages between 1959 and 1967. At the ribbon cutting in 1965, Lady Bird Johnson, wife of President Lyndon Johnson, was in attendance.

The architect, Donald Grieb, took inspiration from Buckminster Fuller, popularizer of the geodesic dome, by creating what was then considered an adventurous design for a botanical garden.

But maintenance has plagued the Domes for decades and the structure has been closed before when public safety was threatened.

In 2000, a master plan for renovation and upgrades recommended spending $32 million, but county officials never moved forward with the proposal.

Mary Spicuzza of the Journal Sentinel staff contributed to this report.