The Horseshoe Bend Water Treatment Plant can be seen on the northeast edge of the Pit. The plant was constructed in 2002-2003 to fulfill the EPA Record of Decision, which requires that surface water flowing into the Berkeley Pit be captured and either used in the mining process or treated.
The plant was designed to treat up to 7 million gallons of water per day using lime (calcium oxide) to raise the pH (reduce the acidity of the water) and remove metals. As pH rises, metals come out of the water and form sludge. The sludge is separated from the water and returned to the Pit at a current rate of about 491,000 gallons per day. Montana Resources incorporates the treated water into their mining process.download full movie The Discovery
In 2012 the plant treated about 5 million gallons of water per day. This water comes from the Horseshoe Bend drainage north of the Pit. The plant has been working continuously since it came online in November 2003. No water or waste leaves the Pit or mine site.