Worker killed in tunnel accident at Lake Mead

June 12--An industrial accident in a tunnel being drilled in solid rock beneath Lake Mead killed one worker and injured another Monday afternoon, the latest and most serious incident at the bedeviled, $800 million construction project.

The workers were erecting large, concrete tunnel support rings 600 feet underground when one ring came loose around 4:30 p.m., releasing a burst of highly pressurized grout that struck the two workers, killing one and leaving the other with minor injuries, said Southern Nevada Water Authority spokesman Bronson Mack.

The two were part of a 12-person team working in the tunnel, which is approximately 20 feet in diameter. The tunnel is still intact and no flooding has occurred, Mack said. At no point were workers trapped inside or exposed to toxic gases, he said.

"Our minds and our hearts and our prayers are with the family of the individual who was fatally struck," Mack said. "Safety has been an utmost concern (for SNWA). There are a lot of safety protocols (in place)."

This is the first fatality on the troubled construction project to build a third intake "straw" at Lake Mead, which has been beset by delays and increased costs since construction began in 2009. The project will be shut down while the Occupational Safety and Health Administration and the Southern Nevada Water Authority investigate, Mack said.

The project was started while Southern Nevada struggled through a decade of drought, and plunging lake levels threatened to drop below the existing two intakes at the lake drilled at shallower depths.

Las Vegas depends on the Colorado River reservoir for about 90 percent of its drinking water.

The third intake would allow the region to continue drawing water from the lake, even if water levels continue to drop.

In July 2010, work on a tunnel that would carry water from the straw into the valley's water system was slowed when crews struck a geographical fault, releasing water and muck into the construction area. Attempts were made to stabilize the fault with grout, but after two more leaks, that tunnel was abandoned and crews began excavating a different direction.

A separate access tunnel also being built as part of the project encountered problems last month when unexpected amounts of water began seeping into the tunnel.

The third intake project was initially scheduled to be finished in 2013, but its completion date has been pushed back until 2014. Mack said Monday's accident should not affect the timeline for completion.

The Associated Press contributed to this report.

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