An industrial tunnel being excavated for Los Angeles County’s wastewater system partially collapsed Wednesday evening in the Wilmington neighborhood, trapping 31 construction workers about 400 feet underground. The Los Angeles Fire Department said all of the workers were freed without visible injuries approximately an hour after the incident. The 18-foot-wide tunnel, part of a $630.5 million project awarded to Dragados USA, runs roughly seven miles beneath the city and is the only access route to the work site. The failure occurred five to six miles south of the entry shaft, between the tunnel-boring machine and the crew. According to interim Fire Chief Ronnie Villanueva, the workers climbed over a 12- to 15-foot mound of loose soil created by the collapse and were shuttled by tunnel vehicle to the surface, where they were hoisted out eight at a time in a rescue cage. More than 100 firefighters, including Urban Search and Rescue specialists, responded, while Mayor Karen Bass thanked first responders on site, noting “no one injured, everyone safe.” Robert Ferrante, chief engineer for the Los Angeles County Sanitation Districts, said the collapse appears linked to “squeezing ground,” a condition in which soil deforms around an excavation. All tunnelling work has been halted pending a detailed structural assessment and safety review.