The Past Butte’s Memory Book tells the story of Jim Ledford, a miner who lived in a log cabin below the famed Anaconda Mine. Alongside his cabin was an old dump containing scrap iron and tin cans. Mine water ran downhill through the dump, and Ledford noticed a heavy sludge formation. Out of curiosity, he had the sludge assayed and […]

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When ARCO suspended underground pumping operations in 1982, groundwater levels on the Butte Hill began to rise. Nineteen months later the water level in the underground workings and surrounding bedrock reached the bottom of the Pit, allowing bedrock groundwater to start filling the Pit void. Prior to that time alluvial groundwater seeped into the Pit from the east and south […]

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Two aquifers feed into the Pit

Aquifers are places where water is found in permeable rocks and soils underground. The area around the Berkeley Pit contains two main underground aquifers – the alluvial aquifer and the bedrock aquifer. The alluvial aquifer is closer to the surface. Water flows freely through the layer of ground called the alluvium, a porous mixture of sands, gravels, and clays. Near […]

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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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Berkeley Pit Myth Versus Fact

PitWatch Issue Volume 9, Number 2 The community has many common misconceptions about the Berkeley Pit. This section addresses a few of those most often heard false statements. Myth: Migratory waterfowl are instantly killed if they land on water in the Berkeley Pit. Fact: Hundreds of waterfowl land on the surface of the Berkeley Pit every month during the migration […]

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