On a chilly morning in November, globe-trotting commercial diver James L. Cross was part of an eight-man crew dangling several hundred feet over the Colorado River near the Hoover Dam.

Their mission: To clean up several hundred thousand pounds of steel cable and debris strewn across the construction site of the new $234 million Hoover Dam Bypass. The mishap occurred on Sept. 15 when a pair of 280-foot-tall steel tower cranes book-ending the Black Canyon bridge portion of the bypass south of the dam collapsed during high winds.

No injuries were reported and the dam wasn't damaged.

But the Hoover Dam Bypass -- which includes 3.5 miles of four-lane highway and a 1,900-foot-long bridge across the Colorado River that ties into U.S. 93 on the east and west -- sustained $50 million in estimated damages and its completion was set back two years to 2010.

Before the cable support structure could be rebuilt, project contractors Obayashi Corp. and PSM Construction USA Inc. had to figure out how to remove up to 300,000 pounds of wreckage lying at the bottom of the Colorado River near the dam.

That task fell to Cross Marine Projects LLC, a commercial diving venture specializing in harbor construction or dam and underwater pipeline repairs. Founded in 1985, the American Fork company has participated in more than 2,000 projects ranging from search and rescue missions to dredging up treasure ships off the Florida Keys.

Cross's environmental projects have even caught the attention of the History Channel, which is developing a documentary series this summer on his efforts to clean up Lake Powell of as many as 250 boats and other sunken aircraft.

But the Hoover Dam Bypass cleanup, which was competed in mid-January, proved to be one of the more challenging projects Cross has ever undertaken in his 30-year diving career.

"It's kind of like taking 30 to 40 cars and trucks, and dumping 30,000 feet of cable over the wreckage, entangling everything like spaghetti, and putting that at the bottom of a fast-moving river. We had to figure out how to unravel all of that, and do it without anyone getting injured," Cross said. "We had to make thousands of cuts to get the cables away from the wreckage and then pick it up piece by piece. The smallest piece of wreckage weighed 33,000 pounds."

That was just the beginning of many challenges he and his divers would face over the three-month cleanup period.

Not only were Cross's divers working daily in icy cold waters averaging 6 feet to 40 feet deep, but the currents were averaging 10 miles to 15 miles per hour. Every day, the dam's gates would randomly release massive amounts of water to generate hydropower. That would raise the river by 8 to 10 feet in a matter of minutes and create huge whirlpools that could endanger unsuspecting divers underwater, he said.

"The diver is like a kite on a string. It's like having an astronaut who is tethered to a space shuttle trying to do a job on a space station, and the shuttle is moving around," Cross said. "Ten miles to 15 miles per hour may not sound like much. But when you're working under water, it's different. You can't anchor the boat with standard anchoring equipment because the bedrock is too smooth and the current too powerful. We had to build a steel mooring cable across the canyon to hold the boat in position, or it'll be swept away."

And the divers, who were underwater for as long as three to four hours at a stretch, constantly faced the danger of losing their lifeline.

"When they open the dam, you can feel the vibration as the turbines start to roll, and you can hear the roar of the water. Even though the water is going downstream, you can get sucked upstream by the whirlpool, and since the boat is swinging about in the turbulence, your air hose is being tugged along and can get cut by the wreckage or even propellers," said Allen Cody, Cross Marine's lead commercial diver.

For Cody, the hairiest situation he faced was when he slipped and was swept 40 feet downstream by the current after the dam gates opened unexpectedly.

"I was wearing 40 pounds to 60 pounds of lead to help weigh me down during the dive. After I was swept downstream, I had to pull myself back to where the project was, with all the weight I had on," Cody said. "When you're diving you have to have safety measure backed up by safety measure. I have an air supply fed to me by the compressor chamber on the boat. If the compressor dies, I have a high pressure volume tank to get me enough air to get out of the water. If I lost the volume tank, I have a Scuba tank on my back."

It was also challenging navigating the Charity Eden, a 42-foot long aluminum catamaran research vessel 11 miles upstream along the Colorado River's shallows and rapids, to get it to the wreckage site, Cross said.

Named after his three-and-a half year old daughter, the Charity Eden was on an expedition to hunt Spanish treasure ships off Marquesas Rock 40 miles off Key West when Obayashi commissioned the company to do the cleanup work at Hoover Dam. The vessel had also been used this summer to recover the three executives who had died in the plane crash in Utah Lake.

Cross declined to reveal the costs of the cleanup project. Typically, Cross's projects bring in revenues ranging between several thousand dollars and up to $4 million per project.

"The costs are still being worked out between the owner and the insurance companies. All the debris has been taken to a storage yard outside of Boulder City where insurers, engineers, and subcontractors are trying to determine what caused the collapse," he said.

The cable system is a critical part of the contractors' operations because it allows materials to be delivered out over the canyon while work is underway on the 1,900-foot-long Colorado River Bridge. An investigation is underway to determine what led the tower cranes to collapse during high winds last September. Wind speeds of up to 55 mph were recorded at the site prior to the tower failure.

When completed, the arch bridge will carry traffic 890 feet over the Colorado River and help reduce congestion, improve highway safety and security to dam operations and visitors.

Cross said his company was recommended by the government because of its 30-year experience in recovery work.

"We had also done work for Obayashi in the past. About 20 years ago, we helped seal ruptured water tunnels under the Strawberry Reservoir basin in Wasatch County," he said.

This story appeared in The Daily Herald on page A1.