Explosives bring down rest of collapsed Florida condo tower in controlled demolition

Demolition crews set off explosives late Sunday to bring down the damaged remaining portion of a collapsed South Florida condo building, a key step to resuming the search for victims as rescuers possibly gain access to new areas of the rubble.

A loud rat-at-tat of explosions echoed from the structure just before 10:30 p.m. Then the building began to fall, one floor after another, cascading into an explosion of dust. Plumes billowed into the air, as crowds watched the scene from afar.

Miami-Dade County Mayor Daniella Levine Cava told The Associated Press after the demolition that it went "exactly as planned." She said the rescue crews had already been given the all-clear to begin work on the mound again.

"It was picture perfect. Exactly what we were told would happen," she said.

Crews were to begin clearing some of the new debris so rescuers could start making their way into parts of the underground garage that is of particular interest. Once there, they were hoping to get a clearer picture of voids that may exist in the rubble and could possibly harbour survivors.

"At this precise moment I feel relief. I feel relief because this building was unstable. The building was hampering our search efforts," Levine Cava said.

No one has been rescued alive since the first hours after the June 24 collapse.

Building was at risk of falling

Rescuers are hoping the demolition will give them access for the first time to parts of the garage area that are a focus of interest. Once a new pathway into the initial rubble is secure, "we will go back to the debris pile, and we'll begin our search and rescue efforts," Miami-Dade Fire Chief Albert Cominsky said.

The decision to demolish the Surfside building came after concerns mounted that the damaged structure was at risk of falling, endangering the crews below and preventing them from operating in some areas. Parts of the remaining building shifted on Thursday, prompting a 15-hour suspension in the work. An approaching storm added urgency to the concerns.

"I truly believe ... that the family members recognize and appreciate that we are proceeding in the best possible fashion to allow us to do the search that we need to do," Levine Cava said.

The mayor said residents in the area were told to stay inside until two hours after the blast to avoid the dust raised by the implosion. Local authorities had gone door-to-door to advise them of the timing, and to ask them to keep windows closed.

The search at the Surfside building has been suspended since Saturday afternoon so workers could begin the drilling work and lay the explosives.

So far, rescuers have recovered the remains of 24 people, with 121 still missing. Many others barely escaped. The Miami-Dade Police Department on Saturday night added Graciela Cattarossi, 48, and Gonzalo Torre, 81, to the list of those confirmed dead.

Elsa adds urgency

Approaching Tropical Storm Elsa added urgency to the demolition plans with forecasts suggesting there could be strong winds in the area by Monday. President Joe Biden declared a state of emergency in Florida because of the storm, making federal aid possible.

The latest forecasts have moved the storm westward, mostly sparing South Florida, but National Hurricane Center meteorologist Robert Molleda said the area could still feel effects.

"We're expecting primarily tropical storm force gusts," Molleda said, referring to gusts above 64 kilometres per hour.

The method used for Sunday night's demolition is called "energetic felling," which uses small detonation devices and relies on the force of gravity. Levine Cava said that would bring the building down in place, containing the collapse to the immediate surroundings so as to minimally disturb the existing mound of debris — where scores of people are believed to be trapped.

Officials used tarps to visually mark the search area, in case new debris scattered unexpectedly.

State officials said they hired the BG Group, a general contractor based in Delray Beach, Florida, to lead the demolition. They did not immediately respond to an inquiry about how the firm was selected, but a contract for the projects calls for the state to pay the company $935,000 US.

A spokesperson for the state's Division of Emergency Management said the company is subcontracting with Maryland-based Controlled Demolition Inc., which experts say is among only a handful of companies in the U.S. that demolishes structures using explosives. The company was supposed to place explosives on the basement and lobby levels of the still-standing structure, according to the contract for the work.

CDI is "probably one of the best" in the industry, said Steve Schwartz, a member of the National Demolition Association's board of directors. He described the company's president and owner, Mark Loizeaux, as "cool, calm and collected."