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Kristin Murphy, Deseret News
The area in the lower center of the frame is where Rio Tinto Kennecott is closely watching for slope movement at the Bingham Canyon Mine on Thursday, April 7, 2016. Workers regularly use geotechnical equipment to monitor movement in the walls.

BINGHAM CANYON — Kennecott Utah Copper has eyes all over its vast Bingham Canyon Mine looking for any potentially dangerous movement of the earth.

Some 400 workers on any given shift are trained to spot geotechnical hazards, whether driving massive dump trucks above ground or mining ore below. But the company deploys a wide array of high-tech instruments to cover the 2 3/4-mile wide, 3/4-mile deep pit in the southwest corner of the Salt Lake Valley.

Radars, GPS trackers, prisms, extensometers, reflectometers and piezometers work in concert to detect the slightest movement — down to hundredths of an inch — or trickle of groundwater. The strategically positioned devices generate round-the-clock data for engineers to analyze in an effort to protect lives.

Kennecott is also testing drones for taking a three-dimensional photo of the open-pit mine and dropping monitors in places where workers can't reach. The 113-year-old mine is the largest man-made excavation in the world.

"We're constantly doing monitoring with our plethora of systems," said David Meador, mine operations manager. "Really, the aim in most of our response plans are around ensuring there's no one in the area well in advance."

Ground movement rates, the size of a crack or rolling rock, triggers a response plan that might include a temporary area closure or reduced mining.

On Tuesday, the company evacuated employees and closed a haul road in the southwest portion of the mine because of what Kennecott spokesman Kyle Bennett described as "minor, localized" movement of debris from a previous landslide. Normal operations resumed after officials deemed the area safe.

"Areas of acceleration are infrequent but not uncommon," Meador said.

Geotechnical workers have now turned their attention to a western slope where spring precipitation, snowmelt and runoff makes it susceptible to shifting. Active mining doesn't take place in that section, but a haul road runs through it.

"We are getting data from all over the mine, but we are watching data from this area particularly close right now," Bennett said.

Kennecott doesn't anticipate any movement to disrupt production or impact workers, he said.

Ground shifting this week wasn't remotely close to the estimated 165 millions tons of rock and dirt that rumbled down the northeast section of the mine in 2013.

Three years ago April 10, a massive landslide buried buildings and trucks and covered about two-thirds of the pit, crippling operations for months. No workers were injured.

"It was monitored and it was predicted and we were able to keep everybody safe," said Joan Danninger, mine technical services manager.

Kennecott puts a lot of money into monitoring inside and outside the mine. But Danninger said it's all about making sure that people can go home to their families in the same condition that they came to work in.

Bennett said the company has returned to business as usual since the crippling slide cut production of mined and refined copper by half for a time. Workers were laid off and not rehired, and Kennecott was still digging out two years later.

"We're in our new normal. We have moved on from what took place in 2013," he said.

Part of the new normal now is dealing with falling prices for metals. Kennecott laid off 200 workers last month.

The company had already reduced costs dramatically through salary freezes, one-off asset sales, inventory reductions and increased production efficiencies. After the layoffs, Kennecott will have about 1,650 employees statewide.

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