A plumbing contractor in Oakland, California, survived being trapped up to his waist in sand and dirt in a 15-foot-deep hole for nearly 13 hours Jan. 13.

Rogelio Esparza, 41, was attaching a lateral to a mainline about 12:30 p.m. when the walls of the trench he was working in collapsed. Officials say plywood used to shore up the walls gave way, trapping the plumber’s feet in sand and debris in a 2- by 3-foot area.

“There was shoring, but I cannot speak to how adequate it was because it was destroyed by the time we got there,” says Mark Hoffmann, deputy chief, Oakland Fire Department. “I got there a couple hours after the initial crew so I’m just going with what the statements were, but apparently they were doing something reasonably routine.”

Hoffmann says while Esparza was in the trench it collapsed into a lower void, along with the shoring.

“He had debris atop his lower legs, which pinned him down. Then all the dirt and sand fell in on that,” Hoffmann says. “The other interesting thing was whatever fill they put in years ago – a boatload of sand. As we would try to move stuff out, other stuff would sluff in from the edges of our shoring. At one point we pulled back and redid all our shoring, laying in more plywood and wire, cutting it precisely to fit the voids. It was a little challenging in that regard.”

Oakland firefighters, with assistance from the Alameda County Fire Department, brought in a large vacuum truck from the city’s sewer division to try and remove some of the sand. A heater also was lowered into the hole to prevent hypothermia.

Esparza, who was working for Star Rooter & Plumbing of Hayward, California, was pulled to safety about 2 a.m. Though cold and shaken, Esparza was alert and talkative and didn’t appear to be injured.

“He was taken to a hospital, but all his vital signs were normal and he didn’t have any outwardly visible injuries,” Oakland Fire Battalion Chief Lisa Baker told the San Francisco Chronicle.

"I don't have the words to thank them for saving me," Esparza told NBC Bay Area. "Thanks to them and thanks to God."

Star Rooter was cited by the State of California Division of Occupational Safety and Health (Cal/OSHA) for a similar incident on Aug. 8, 2013, when it failed to ensure a 10-foot-deep trench was protected from cave-ins by an adequate protective device and failed to provide a stairway, ladder, ramp or other safe means of egress from a trench more than 4 feet in depth. The company was fined $3,640.

The latest incident is under investigation.

According to OSHA, excavation and trenching are among the most hazardous construction operations. OSHA defines a trench as a narrow underground excavation that is deeper than it is wide and no wider than 15 feet. Trenches 5 feet deep or greater require a protective system, unless the excavation is made entirely in stable rock. Trenches 20 feet deep or greater require that the protective system be designed by a registered professional engineer or be based on tabulated data prepared and/or approved by a professional engineer.

Worker trapped in 13 ft hole that collapsed while attaching sewer lateral to main line in @CityofOakland. pic.twitter.com/EreEnA9J1b

— alan wang (@AlanWangABC7) January 13, 2016