BUTTE, Mont. (AP) — The long-awaited discharge of treated wastewater from a former open pit copper mine into Silver Bow Creek in Butte has started with little fanfare.
The discharge from Berkeley Pit is being done by Montana Resources and Atlantic Richfield Co. The work by the companies began Monday, four years ahead of the point when acidic, metal-laden water from the mine could reach the water table.
Berkeley Pit was allowed to fill with groundwater beginning in 1982 and listed as a Superfund cleanup site in 1983.
The water level has been rising while regulators and responsible parties developed a plan to treat the water.
U.S. Environmental Protection Agency regional director Greg Sopkin called the release of water a milestone.
"This reflects the significant progress being made toward a final remedy for the Berkeley Pit water and the Silver Bow Creek watershed," Sopkin said in a statement emailed to The Montana Standard .
Montana Resources is pumping water from the pit, and Atlantic Richfield is treating it, proving "that we can actually hold the water level steady in the pit," Ron Halsey, an operations manager with Atlantic Richfield, told Montana Public Radio .
The water is treated to remove metals and alter its acidity and used for mining operations before being sent to a tailings pond for settling.
Water from the pond is treated at a new plant and released — at a rate of about 6 million gallons (22.7 million liters) a day — into the once badly polluted creek.
"Discharge rates will vary based on Montana Resources' needs for water to operate their mining activities and on local stream activities," said Michael Abendhoff, the Chicago-based spokesman for BP, which owns Arco.
The EPA gave its approval for the companies to begin releasing water last week after tests showed the water quality met federal and state standards, Abdendhoff said.
Residents were glad to see the progress and hope someday another stretch of Silver Bow Creek can be reclaimed and the treated water released there.