Mining contaminated waters to increase copper supplies

The massive Berkeley Pit in Butte, Montana, is one of the world’s largest superfund sites and has been described as a giant sink filling with metal-laden, acidic water from over 10,000 miles of underground mine workings.

It has been a ticking time bomb since 1982 when the mine owner turned off the pumps which kept the subsurface tunnels dry for miners. The pit has collected 50 billion gallons of toxic water.

While the rising pit water is a looming environmental threat if it seeps into the area’s groundwater, it may be a new source of copper if a pilot plant pans out. However, if left unattende...