Study details slope stability

The rate of rise of water levels in the Berkeley Pit and connected monitoring points is affected by many factors, including rain and snowfall and occasional ‘sloughs’ or ‘slumps’ of material from the Pit’s sidewall slopes. The most recent slough occurred on February 8, 2013. An estimated 820,000 tons of material from the southeast wall collapsed into the Pit. Montana […]

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Berkeley Pit slough

On February 8, 2013 material from the southeast wall of the Berkeley Pit collapsed into the Pit water in what is known as a rotational slump or slough. Such sloughs are relatively common in open pit mines. For example, a similar slough occurred at the Berkeley Pit in 1998. The recent slough was about 550 feet wide and caused an […]

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What if an earthquake were to strike?

There are several reasons why we don’t need to be overly concerned about the Pit in the event of an earthquake, including the fact that there has been no significant seismic activity in nearby faults during the 28 years that the Earthquake Studies Office has been monitoring the area. In the mining region, the recorded seismic activity is mainly caused […]

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Yes. Wet weather may have also played a role in the 1998 Pit wall slough that sent about 3 million tons of rock and dirt into the water. Rising groundwater saturated and gradually weakened that section of the southeast wall, eventually causing it to break away. Montana Resources, Inc. (MR) is taking steps to stabilize the piles of waste rock […]

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A 5.6 magnitude earthquake centered near Dillon on July 25, 2005 did not affect the Berkeley Pit. There was no Pit wall sloughing or change in the water levels in the Berkeley Pit, the underground mine shafts, the alluvial aquifer wells, or the majority of the bedrock monitoring wells. However, two bedrock monitoring wells (A&B) showed changes. Well A showed […]

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