Officials announced Friday, July 23, that firefighters completed their goal of cleaning debris from the collapsed Surfside condo building while police and forensic specialists continue to search through the debris pile for other bodies and personal effects. According to authorities, the oceanside tower collapsed on June 24, killing 97 people and leaving at least one more person missing and unidentified.

The fire department’s 24-hour operation at the oceanfront site of the Champlain Towers South condo in the Miami neighborhood of Surfside was demobilized four weeks and one day after the 40-year-old, 12-story complex collapsed while residents slept at approximately 1:30 a.m.

“At this step in the recovery process it has become increasingly challenging to identify victims, and we are relying heavily on the work of the medical examiner’s office and the scientific, technical process of identifying human remains,” Miami-Dade Mayor Daniella Levine Cava said in a statement.

She praised members of the search and recovery teams as “real superheroes.”

No one has been rescued alive from the pulverized concrete mounds, and authorities officially gave up hope of finding survivors on July 7. According to county officials, the verified death toll is 97, with 96 fatalities whose remains were found amid the debris and one victim who died while hospitalized.

“We believe there is one victim still unaccounted for,” the statement said.

Collins Avenue could collapse because a remaining perimeter wall near the road could fail, according to Structural Engineer Allyn Kilsheimer, who wrote a letter to Surfside and Miami-Dade officials on Thursday, July 22. The Miami Herald and WPLG reported the first development on Friday.

“We believe there is a potentially dangerous situation at the site, where the wall is in danger of collapse,” Kilsheimer wrote.

The walls of the underground parking garage, which surround a hollowed-out foundation, are all that remains of the Champlain structure, according to Kilsheimer. Without extra support for those walls, nearby traffic could cause them to collapse, with parts of the street falling into the gap.

“If the wall were to collapse or rotate substantially, the retained soil under the street and sidewalk could move with it,” wrote Kilsheimer of KCE Structural Engineers.

To reinforce the walls near the street and walkway, he suggests adding an earthen berm. Otherwise, he said, the movement “could cause portions of the street to collapse and could seriously compromise the utilities under the street,” he wrote.

According to Rachel Johnson, the county’s communications director, Miami-Dade County is putting in crews to help shore up the remaining underground walls.

“We are moving to procure a company to do shoring and bracing of the walls to assure there is no risk,” she said.