The Berkeley Pit is a former open pit copper mine located in Butte, Montana, United States. It is 1 mi (1,600 m) long by 1⁄2 mi (800 m) wide with an approximate depth of 1,780 feet (540 m). It is filled to a depth of about 900 feet (270 m) with water that is heavily acidic (2.5 pH level), about the acidity of Coca-Cola, lemon juice, or gastric acid. As a result, the pit is laden with heavy metals...
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