Engineers evaluate demolition options to prevent 'mess of immense proportion' in Surfside

SURFSIDE, Fla. – Engineers were evaluating options Friday for demolishing the remaining portion of a condo building that partially collapsed outside Miami last week, leaving 22 people dead and 126 unaccounted for.

Miami-Dade County Mayor Daniella Levine Cava said she signed an emergency order to demolish the remaining portion of Champlain Towers South, once engineers have signed off on the project, given the structure's imminent threat to public health and safety.

There is no specific start date for the demolition, which would likely take "weeks," Levine Cava said in a Friday evening news briefing. Engineers are meeting regularly to determine what the demolition process would look like, and officials' top priority remains search and rescue, she said.

"We're very concerned to not compromise our search, but we also know that the building itself poses risks. So we have to balance those things," Levine Cava said, adding, "As to where the demolition would fall, that is part of the calculus. There are many, many factors. There are many choices to be made. And all of that is being reviewed by the engineers."

Concerns about the stability of the remaining structure pushed officials to suspend rescue efforts Thursday for about 14 hours. On-site engineers identified one column that had shifted 6 to 12 inches and three cracks that were expanding in the building, which looms over the search-and-rescue teams sifting through large heaps of rubble near its base.

With newly formed Hurricane Elsa speeding toward Florida, Surfside Mayor Charles Burkett said Friday he wanted to fast-track the possible demolition of the remaining section. Burkett said rescue teams searched the building "up and down, at least three times" and had drones flying in and around the structure.

"In most cases, setting up for a demolition is a time-consuming effort in testing and making that sure it doesn’t have asbestos. There’s a list of things that you do. But we’ve got a potential hurricane coming that’s going to demolish it for us," Burkett said, addressing reporters after the press conference.

"And if that happens – and it just happens to blow it the wrong direction – it could be a mess of immense proportion," he said.

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Burkett said he raised the topic Thursday morning with Florida Gov. Ron DeSantis. Burkett said if the U.S. can send men to the moon and launch missions to Mars, engineers should be able to demolish the damaged condominium structure within 24 hours if needed.

"I think it would be better if we demolished it and pushed it in the direction that we want – as opposed to the storm demolishing it and pushing it in the direction it wants," Burkett said.

Others feared the demolition could take longer.

"It cannot be before this storm," Levine Cava said Friday. "However, it is storm season. We know that the building is unstable. We are going to move forward with demolition, we just have to do it in the safest possible fashion."

Scott Nachman, structure specialist with FEMA’s search and rescue incident support team, said Thursday it would take weeks to establish a demolition timeline in the "best-case scenario."

Alpha Wrecking, a demolition-specific contractor based in Pompano Beach, Florida, was on site and did not immediately respond to USA TODAY request for comment.

Elsa is expected to emerge off the coast of Cuba by Sunday night or Monday morning – and South Florida could experience tropical-storm force winds on Sunday, Monday or Tuesday, Robert Molleda, the warning coordination meteorologist with the National Weather Service in Miami, said Friday.

Atlantic tropical storms pack maximum sustained surface winds of 39 to 73 mph.

"There is a lot of uncertainty in the forecast: how it will evolve, how the storm will interact with the land areas that are to our south," Molleda said. "And that could affect not only the intensity, or how strong the storm is, but also the track that it takes."

Nancy Pashkoff, 55, who has lived in Florida for 35 years, said it's been "heartbreaking" to watch the scene unfold in Surfside and that she can barely keep herself from crying at work.

She's closely watched the recent announcements of demolition considerations. "I'm concerned they might do it sooner than planned with storms approaching," Pashkoff said.

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Engineers and demolition companies not directly involved in the planning were divided on how best to take down the building. There are several common demolition methods, including a wrecking ball, implosion, or a high arm reach that deconstructs the building from the top down.

Mehrdad Sasani, a professor of civil and environmental engineering at Northeastern University in Boston, said he suspects officials would choose to demolish the building by implosion given its height and size – a process that involves the strategic placement of charges to direct the way the buildings falls.

"If they implode the building, they can control the way it’s going to fall and divert it away from where they’re searching," said Tony Stern, president of Riteway Demolition in Sunrise, Florida. "They could put people underneath the building and implode it without putting people on top of the pile where they’re searching."

John Wallace, a professor of structural engineering at the University of California, Los Angeles, said he suspected demolition would be unlikely until search and rescue is completed. Any vibrations associated with the collapse of the tower could impact the existing rubble pile, causing it to compact and tighten any voids, he said.

Earlier this week, Miami-Dade Fire Rescue Assistant Chief Ray Jadallah said crews had identified additional voids in the rubble where residents could be located, but there is no evidence anyone is inside.

Once officials move to the recovery phase, it would make sense to demolish the remaining portion of the building before finishing the recovery effort, Wallace said.

"This will, of course, not be an easy decision. But removing debris from the existing rubble pile does have the potential to destabilize the remaining, standing portion of the building, and, even with very close monitoring, it is a challenge and not without significant risk," he said.

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Joshua Galanter, project coordinator at Thunder Demolition Inc. in Miami, said it typically takes months of engineering, preparing and rigging explosives on the main support columns for a controlled implosion.

"They may circumvent the usual planning and approval these projects entail because this is a special emergency circumstance. But I would find it highly unlikely the remaining structure comes down within the next 30 to 60 days," Galanter said.

Abi Aghayere, a Drexel University engineering professor, said he suspects officials may choose to mechanically take down the building. Use of a wrecking ball would pose a great risk to surrounding buildings, and the vibration of an implosion could possibly disturb or crack other buildings, too, he said.

"The way that the structure came down on itself, that’s what implosion tends to do. That way, the debris field is confined, not scattered all over the place. But when you do that, you may have other buildings impacted," Aghayere said.

A vacation resort complex and a condominium tower border the Champlain Towers property to the north and south, respectively, and busy Collins Avenue lies just to the west. Pulling off an implosion demolition in time would require engineers to inspect nearby buildings to determine the potential impact of the explosion, he said.

The method could also come across as insensitive to those who have been bereaved and whose loved ones still haven’t been found, Aghayere said.

"We are left with, really, one method, where you have a long arm, high reach excavator that tends to take the structure down piece by piece," he said.

Even that method poses risks, he said, if the building then becomes unstable and falls.

"They must be careful in choosing which method will be used, taking into account the families who have lost loved ones in this building," Aghayere said.

Contributing: Katherine Lewin, Jacksonville.com. Hauck reported from Chicago.

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This article originally appeared on USA TODAY: Miami condo collapse: Engineers exploring demolition options