Lost jobs, robotic mining, halved production, and lower tax revenues are some of the consequences of what experts say may be the most successful landslide event ever at Bingham Canyon.
RENO (MINEWEB) – On April 10th this year, one of the world’s largest landslides tumbled 150 million tons of rock and dirt down the northeastern pit wall of Kennecott Utah’s Bingham Canyon copper-gold-molybdenum mine, likely becoming one the more expensive landslides in modern history.
The U.S. Geological Survey estimated that the landslide unleashed 128 million cubic yards of rock and dirt into a pit nearly a mile deep, equal to about two-thirds of the material removed for the construction of the Panama Canal. Put another way, however, the largest landslide in modern history, the 1980 Mount St. Helens eruption, loosened 3.7 billion cubic yards.
Perhaps the biggest victory of this event was the ability to forecast and plan for it. Pit wall movement for the 24-hour/7-days-a-week operation was first detected in early February. A combination of radar, prisms and geotechnical sensors was employed to gather data used in mine planning. Mine employees were trained to observe and make slope stability determinations in areas that impacted their work.
By April 10th the accelerated trend of the slide had reached a velocity value of 2 inches per day, all mine personnel were evacuated from the area surrounding and below the slope. The slide occurred at 9:30 p.m. that evening.
Despite the extensive monitoring and data gathering, the size and travel distance of the landslide was not anticipated. The first slide was anticipated; however it generated a second event which traveled further into the pit than anticipated—both events unfolded over a 20-30 minute time period.
Jobs, buildings and heavy equipment were lost; however, the 350 employees who normally work the night shift had been previously evacuated and were safe. “Nobody was hurt. That was a very big deal for us,” said Kennecott spokesman Kyle Bennett
However, three shovels out of a 13-shovel contingent, 14 trucks out of a 100-truck fleet, and ancillary equipment including drills, bulldozers and graders were damaged or buried by the slide.
Limited operations resumed the next day on the southeast portion of the mine that was not impacted by the fleet. The in-pit crusher and conveyers were not damaged but the primary access road to the operation was destroyed. A hair-pin corner of a secondary road had to be fixed before safe access to the pit was viable.
In what was probably the first use of a corporate Facebook page by a global mining company for emergency communications, Kennecott launched in-house, daily news coverage on Facebook of the landslide fron April 11th. Numerous photos of the slide and its impacts were posted by Kennecott on the website flickr.com to ensure unfettered media access. Videos have been posted by the company on the website vimeo.com
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