LAKE MEAD, NEVADA (BNO NEWS) -- A tunnel under construction at Lake Mead in southern Nevada collapsed on late Monday afternoon, killing one construction worker and injuring another, officials said on Tuesday. Other workers managed to escape safely.
The accident happened at approximately 4:30 p.m. local time when a small group of workers were setting concrete segments about 600 feet (182 meters) below ground at a project area near the Lake Mead National Recreation Area. It is part of a project to drill a third drinking water supply line to the Lake Mead reservoir, which supplies 90 percent of drinking water in Las Vegas.
"During this process, one of the tunnel segments was jarred loose, and pressurized grout was discharged, striking two of the workers," the Southern Nevada Water Authority (SNWA) and its contractor Vegas Tunnel Constructors said in a joint statement on Tuesday. "We have confirmed that one of the workers was fatally struck; the other suffered minor injuries."
The name of the victim was not immediately released.
Initial media reports suggested more than a dozen workers were trapped and exposed to toxic gasses by the collapse, but the water authority rejected these reports. "All other workers have been accounted for and are safe above ground," the statement said. "Furthermore, there was no flooding of the tunnel."
A team of investigators descended into the tunnel on Tuesday morning to examine the site of the accident and determined it was safe for entry. Vegas Tunnel Constructors (VTC) workers are cleaning the space and are preparing to seal the approximate four-inch (10 cm) by two-foot (60 cm) gap where the tunnel ring segment slipped forward, allowing pressurized grout to force through. The company says the concrete segment did not fall into the tunnel.
"The amount of material that forced through the opening was about one-half of a cubic yard (0.3 cubic meter) with some 2-inch to 4-inch (5 to 10 cm) size rock mixed with grout and mud," the companies said in a statement. "No further material has come into the tunnel. One hundred thirty-three of these concrete rings have been successfully put in place by the tunnel boring machine and crews, with a total of nearly 2,500 expected to complete the tunnel. All of the installed segments are stable."
The SNWA Intake No. 3 project was launched to relieve drought conditions in the state.
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