Berkeley Pit

Berkeley Pit

Owner: Atlantic Richfield Company

Type of Mine: Copper, Silver, Gold

Location: Montana, United States

Built: 1955

The Berkely Pit closed 30 years ago in 1982.  Since then, without water pumps running to keep shafts open, rainwater has filled much of the 540 meter deep pit.  Despite looking crystal clear from above, the pit is now a soup of dangerous heavy metals and hazardous chemicals such as arsenic, sulfuric acid and cadmium.  In fact, the water is so saturated with minerals that Montana Resources is able to pump the water into holding ponds and harvest up to 180 tonnes of copper a month.

The mine, which opened in 1955 produced 1 billion tons of material and grew so large that the original mine owner, Anaconda, bought the neighboring community so that it could continue expansion.

Image courtesy of NASA, Earth Observatory; Berkely Pit, 2 August 2006

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