Pool deck likely cause of Surfside condo collapse: investigators

Federal investigators examining the deadly collapse of the Champlain Towers South condominium building in Surfside, Florida, are leaning toward the conclusion that the building’s pool deck was the likely cause of the building giving way. 

Investigators for the National Institute of Standards and Technology (NIST) on Thursday issued an update on the agency’s near three-year probe into the shocking and sudden collapse of the 12-story, L-shaped Champlain Towers South building that killed 98 people in June 2021.

NIST said a team of engineering, geotechnical, social science, material science and other experts have been gathering and analyzing evidence to understand what caused the collapse. The investigation, which has already cost $30 million, includes speaking with eyewitnesses, testing materials from the collapse site, creating complex computer models and analyzing video footage.

Gini Gonte visits the Surfside Wall of Hope Memorial on July 7, 2021 as she honors her friends Nancy Kress Levin and Jay Kleiman, who lost their lives after the collapse of the Champlain Towers South in Surfside, Florida. (Al Diaz/Miami Herald via AP)

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A widely shared video of the incident shows the center of the building giving way and collapsing before another section of the building quickly follows suit, all in a matter of seconds. 

Another video taken by a tourist on the night of the collapse showed water gushing into the garage and chunks of concrete covering the floor on the north side of the building. Investigators said that video is evidence that the pool deck – located at ground level above an underground parking garage – collapsed into the parking garage before the east portion of the tower collapsed, the Miami Herald reported.

The building partially collapsed on June 24, 2021. About 10 days later, what remained was demolished. 

Thursday's meeting focused on design defects in construction and a lack of meeting safety standards that were in place at the time, as well as those in effect back in 1979 when Champlain Towers was first being built, according to CBS News.

An aerial image shows the building having partially collapsed. An ongoing probe into the deadly collapse of the Champlain Towers South condominium building in Surfside, Florida, is leaning toward the building’s pool deck as being the cause. (AP Photo/Gerald Herbert)

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Investigators said the design of the pool deck and tower did not meet strength and other requirements of that time.

"We have very, we think, conclusive evidence now that the pool deck collapsed before the tower did in a gross manner," said Glenn Bell, a team associate lead with Champlain Towers South NCST NIST.

Fahim Sadek, project leader, Champlain Towers South NCST NIST, said that several columns may have had strength deficiencies that did not comply with the original codes and standards, CBS News reported.

Sadek said to determine what caused the collapse, investigators have been examining columns, concrete mixtures, corrosion, the building's foundation and the effects of vibrations from construction from neighboring buildings.

Investigators said it has been narrowed down to about two dozen failure hypotheses, with one of the most likely scenarios being the pool deck slab-column connections.

They are examining signs that the concrete that provides protection to the rebar was compromised by cracking, resulting in corrosion, noting that there was a history of water leaking into the garage and around the pool.

This aerial photo shows part of the 12-story oceanfront Champlain Towers South Condo that collapsed on June 24, 2021, in Surfside, Florida. (Amy Beth Bennett/South Florida Sun-Sentinel via AP)

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"The whole goal from this investigation is to learn from it and bring about improvement in codes and changes in practice to minimize the chance that a disaster like this terrible tragedy could happen again," said Bell, according to CBS. 

CBS also reported that the pool deck collapsed more than four minutes before the building, but that does not necessarily mean the collapse started there. 

Investigators are considering about two dozen failure hypotheses and are seeking to rule out less likely causes such as a sinkhole in the limestone underneath the tower or uneven settlement of the building’s foundation.

The probe has found no evidence of an explosion or other extraordinary event that could have triggered the incident, according to the Miami Herald. Several flashes could be seen as the building collapsed.

Nonetheless, investigators said that they had not ruled out the possibility that something in the towers had initiated the collapse.  

Fox News’ Greg Norman contributed to this report.