Fire Department Chief Ronnie Villanueva said the workers had to make it through the most treacherous part themselves, climbing over more than 12 feet (3.6 meters) of loose dirt and debris to reach the boring machine before rescuers could drive them to the opening of the nearly $700 million project, which is designed to carry treated wastewater to the Pacific Ocean.
Aerial footage showed a crane hoisting workers out of the tunnel in a yellow cage. None had major injuries, authorities said.
The accident happened as workers were operating the boring machine, said Robert Ferrante, chief engineer and general manager for the sanitation districts. “A section that they have already built had squeezing ground and had a collapse, a partial collapse,” he told reporters.
Arally Orozco said she was at church when her phone started buzzing with calls and her son texted her the news of the tunnel where her three brothers worked.
“It was sad and scary,” she said in Spanish. “We feared the worst.”
After an hour, she managed to get through to one brother who told her they had to squeeze through a tight space to get out.
“My brother was crying,” she said. “He told me he thought he was going to die underground.”
The collapse in the tunnel, which is 18 feet (5.5 meters) wide and will be 7 miles (11.3 kilometers) long, happened under the Wilmington neighborhood, a heavily industrial area filled with oil refineries just north of the Port of Los Angeles.
Working so near the shoreline and at such a depth means crews could have been contending with very wet conditions that add challenges during design and digging, said Maria Mohammed, president of the Structural Engineers Association of Southern California.
“You would design not just for the pressure from the soil and the weight of the soil, you have to design for the pressure from the water,” said Mohammed, whose group is not involved in the Wilmington project.
The cause is under investigation, Chee said. Work will not resume until they can figure out what happened and determine that it’s safe to proceed, authorities said.
Mohammed said that investigation could take months, if not longer. It will take some time just to make the tunnel safe for investigators to enter. Once inside, they'll try to determine where the collapse originated, she said.
“It all comes down to, what’s the first element that broke?” Mohammed said Thursday. “Usually a collapse is a propagating thing. One thing fails and it takes other things with it. So you would try to figure out, of the broken elements, which one broke first.”
City Councilmember Tim McOsker praised the workers for keeping cool heads.
“This is a highly technical, difficult project. And they knew exactly what to do. They knew how to secure themselves,” he said. “Thank goodness for the good people that were down in the tunnel.”
Mayor Karen Bass said at a news conference that she met with some of the workers.
“I know when we raced down here I was so concerned that we were going to find tragedy. Instead, what we found was victory," Bass said. "All of the men that were in that tunnel, rescued, up, safe.”
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Associated Press writer Christopher Weber in Los Angeles contributed.
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