Berkeley Pit

This picture was taken off Continental Avenue in Butte, Montana.  The Berkeley Pit is a former open pit copper mine that got its name from one of several nearby underground mines.  In 1955 excavation on what would become the Berkeley Pit began the transition from underground to open pit mining.  Production peaked in 1962 when 320,000 tons of total ore per day were being mined.  In 1982, Atlantic Richfield Company, which bought the Anaconda Company in 1977, decided to halt production as mining copper had become significantly less profitable. Today the real concern is the water that is filling up the Pit, projected to reach the city's water table in the early 2020s time frame.  The water has high concentrations of copper, cadmium, cobalt, iron, manganese, and zinc, making it very acidic (pH of 2.5) similar to soda or vinegar.  The Pit measures 7,000 feet long, 5,600 feet wide, and 1,800 feet deep.