This kind of traffic has been missing from the mine since April 10, when the northeast wall of the open-pit mine gave way, spilling 165 million tons of rock and dirt, eventually piling up 300 feet deep in the pit.
A University of Utah scientist calculated it may be the largest landslide in North American history, other than earth movements triggered by volcanoes.
"The slide was a defining moment in the history of the mine," Lengerich said, calling this week's opening of the access road a "major milestone" in Kennecott's plan to restore Bingham Canyon to full production by 2016.
While it's taken almost seven months to build the access road, that was six months less than projected, he noted, praising employees for coming up with innovative ways to do the job better and faster.
"They never backed down from a challenge," Lengerich said, and did so without a singlework-time injury.
Much of the early recovery work involved the use of 20 pieces of remote control-operated equipment that pushed at the slide zone from the top and sides, producing an angle of repose that engineers are confident is stable, Lengerich said.
About one-third of the way down the scar, the access road cuts through the slide zone like a cat-track traversing a ski run. The road's broad surface was reinforced in this stretch with 2.2 million tons of rock from the slide, he noted, with roughly 200 workers taking part in various aspects of the around-the-clock operation.
One result of this effort is that Kennecott's parent company, Rio Tinto, projected that copper production from the Bingham Canyon Mine will bounce back to 200,000 tons in the year's third quarter.
After the slide, company officials said the damage would cut production in half, well below that revised goal.
Having the mine access road in place will accelerate company efforts to get back to higher production levels. Right now, Lengerich said, 30 pieces of equipment are poised to begin excavating the next targeted ore segment, work that could begin in two to three weeks as crews plug away at removing the 100 million tons of waste rock that remain in the pit bottom.
Along with restoring production, Kennecott spokesman Justin Jones said the recovery effort has reached 10 of the 13 haul trucks and shovels buried by the slide.
Four are back at work, he noted, but a couple of the $5.5 million trucks were battered so badly by the flowing boulder field that they will have to be salvaged as scrap metal.