The Horseshoe Bend Water Treatment Plant, completed in 2003, captures surface water to slow the rate of fill of the Berkeley Pit lake. In the future, the plant will capture and treat water to prevent Pit water from rising further.
Water from the Horseshoe Bend drainage is diverted before reaching the Pit and treated in the Horseshoe Bend Water Treatment Plant for use in mining operations. In 2012, the plant treated about 5 million gallons of water per day. Sludge from the treatment process was returned to the Pit at a rate of 491,000 gallons per day. No water or waste leaves the Pit or mine site.
Water levels in the Pit, wells and mine shafts are monitored monthly. An evaluation of the rate of fill is performed each year to determine dates for future reviews and plant upgrades.
Berkeley Pit groundwater monitoring locations and water levels, including wells and abandoned mine shafts, June 2013. Click on the image to view a larger version.
Monitoring compliance points in the Berkeley Pit groundwater system. The water level a each point is monitored monthly by the Montana Bureau of Mines & Geology. When the water at any compliance point reaches the Critical Level (5,410 feet above sea level), pumping and treating of Berkeley Pit water will begin to prevent contaminated water in the Pit and groundwater system from spreading outward. Click on the image to view a larger version.