Work is shut down for the foreseeable future at the troubled third intake tunnel at Lake Mead, as investigators and engineers try to sort out the cause of an accident Monday that killed a worker 600 feet underground.
Officials are fairly certain how 44-year-old Thomas Albert Turner was killed, but construction will not resume until they know how to keep it from happening again, said Scott Huntley, spokesman for the Southern Nevada Water Authority.
A team from the Nevada Occupational Safety and Health Administration descended into the tunnel roughly 55 stories beneath Lake Mead’s Saddle Island on Tuesday morning to inspect and photograph the accident site.
In a statement, Steve Coffield, chief administrative officer for Nevada OSHA, said construction activities are suspended until the cause has been identified and corrected and the safety of the tunnel has been verified. He could not say how long the probe might take.
The accident is bringing new scrutiny to the roughly $800 million project, which has suffered several major setbacks over the past two years.
Federal OSHA records document eight inspections at the site since August 2008, including three inspections that were triggered by complaints to safety officials.
Two of the eight inspections identified multiple safety violations by general contractor Vegas Tunnel Constructors, records show.
A complaint led to an inspection of the site on Oct. 1, 2009, that found five safety violations, including two that were deemed serious. Three of the violations, including the two serious ones, were later disputed and overturned, but records show Vegas Tunnel Constructors was fined $500.
Then on July 2, 2010, one day after the underground work site flooded with water and debris, inspectors logged nine more safety violations, four of them serious. Six of those violations, including all of the serious ones, were overturned, but the contractor was fined another $2,500.
Records also show that Turner was not the first worker to die at the third intake site.
On Feb. 22, 2010, a hoist operator fell ill and later died as co-workers tried to get him medical help.
The Clark County coroner’s office ruled that 63-year-old Jose Chavez died of natural causes associated with heart and kidney disease and diabetes, but the OSHA inspection report notes several problems with the way the on-site safety personnel responded during the incident.
According to the report, Chavez was the only one on the site at the time qualified to operate the hoist that lowers workers down the 600-foot access shaft and brings them back up.
The report said Chavez wasn’t feeling well and contacted the site’s safety manager, who came to check him out. The man’s vital signs were stable, and he was downplaying his illness, so the decision was made for him to keep working long enough to hoist the current shift of workers up from the tunnel.
That took about 20 minutes, after which a co-worker walked Chavez to the first aid trailer. But his condition continued to quickly deteriorate.
The report said the safety manager called the National Park Service – the closest emergency response agency – but “could not remember the address of the construction site,” so he put Chavez into the safety truck and drove him out to the main park road.
During the trip, Chavez became unresponsive, and attempts to revive him failed. He was pronounced dead three hours after he first reported that he wasn’t feeling well.
Monday’s accident occurred as a crew was assembling one of 2,500 rings of concrete pipe that will line the finished three-mile tunnel.
Huntley said the preliminary investigation indicates a section of pipe ring “slipped,” creating a 2-foot-by-4-inch gap that allowed a pressurized grout mixture to shoot through.
Turner was struck by the mixture and killed. Another worker suffered minor injuries.
The grout is made from a combination of cement, sand, water and ash, but Huntley said the stream of material that hit the workers also contained mud and rocks as big as a fist.
The mixture is used to fill the space between the rock walls of the 23-foot-tall tunnel and the 20-foot-diameter pipe that will line it. For the grout to work, it has to be pressurized to about 200 pounds per square inch, roughly five times the force produced by a garden hose running full blast, Huntley said.
The accident came less than a week after another worker down in the tunnel stepped off a platform the wrong way and had his foot struck by a pipe segment.
The man broke a toe and another bone in his foot and needed stitches, but he was back on the job in short order, Huntley said.
“This isn’t like sitting in your living room knitting,” he said. “It’s a difficult and dangerous job down there.”
By all accounts, the third intake is the most complicated and expensive construction job in the history of the water authority.
When finished, it is expected to keep water flowing to Las Vegas even if the lake shrinks enough to force one of the two existing straws to shut down.
The Las Vegas Valley depends on the Colorado River’s largest reservoir for about 90 percent of its drinking water.
The water authority board approved a rate increase earlier this year to help cover the last $360 million of the intake project, which already was running about 20 months behind schedule prior to Monday’s accident.
The delay was caused by a series of floods in the work area in 2010 and 2011 that forced the contractor to abandon its first tunnel and excavate a new one in a different direction.
Review-Journal writer Kyle Potter contributed to this report. Contact reporter Henry Brean at firstname.lastname@example.org or 702-383-0350.