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Open pit mining is also much less hazardous for the miners themselves. Best guesses put the number of deaths in Butte’s underground mines, which operated for about a century from the 1860’s through 1976, at around 2,500, an average of about 25 deaths per year. Only six fatalities occurred over the life of the Berkeley, which was operated for 27 years from 1955 through 1982. The Continental Pit, which has been mined intermittently since 1980, has seen only one death. But steep, continuous declines in copper prices following the 1974 spike led to the eventual shut down of Berkeley operations in 1982.

The Berkeley Pit in 1979-80, several years before the closure of the mine. Photo from the Library of Congress, Aug 79 Jan 80 Historic American Engineering Record (HAER) shoot.
The Berkeley Pit in 1979-80, several years before the closure of the mine.

Throughout the history of mining in Butte, pumps were used to dewater the underground mines and, later, the Berkeley Pit. On April 23, 1982, the Atlantic Richfield Corporation (ARCO, today owned by British Petroleum), the owners of the former Anaconda Company holdings, announced that they were suspending their Butte operations. Along with the announcement, the underground pumps in the Kelley Mine were shut down. The result: the underground mines and the Berkeley Pit began to fill with acidic water.

The great advantage of the Berkeley is that it acts as a terminal sink: all contaminated ground and surface waters from Butte’s East Camp flow to it and are captured in it. Since 1982, ARCO, Montana Resources, the EPA, the Montana Department of Environmental Quality and the local community have risen to the unique challenges of managing the Pit.

Elevations above sea level for Berkeley Pit water and surrouding Butte, Montana landmarks. Map image from Google Earth, graphic by Justin Ringsak.
Elevations above sea level for Berkeley Pit water and surrounding Butte, Montana landmarks. Click on the image to view a larger version.

Historically, Butte’s resourcefulness made it a successful mining town that has far outlived the boom-and-bust cycle of many similar communities. That resourcefulness is today being applied in new ways in the many environmental restoration projects underway in the area, and in the management of the Berkeley Pit, all while mining continues successfully, and in ways that alleviate the impacts on the environment, just next door to the Berkeley at the Continental Pit. In fact, it can be said that mining continues today in the Berkeley Pit as Montana Resources is recovering the dissolved copper that exists in the water contained within the walls of the Pit.

Just as Butte transitioned from underground to open pit mining in 1955, today the community is in the midst of an exciting transition from a landscape scarred by mining to a landscape that is restored where possible and managed responsibly.


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