This image from the Montana Bureau of Mines & Geology illustrates the connections between historic underground mining tunnels and the Berkeley Pit. After groundwater pumping ceased in 1982, the tunnels, and eventually the Pit, began to fill with water.

This image from the Montana Bureau of Mines & Geology illustrates the connections between historic underground mining tunnels and the Berkeley Pit. After groundwater pumping ceased in 1982, the tunnels, and eventually the Pit, began to fill with water. Click on the image to view a larger version.

Since the last issue of PITWATCH, Montana Resources has decided to resume operations. With the mine going again and with the water treatment plant coming on line, there have been many questions from the community. Here are some answers to reader questions.

Q: How much total water went into the Berkeley Pit since the suspension of mining at Montana Resources?
A: About 7.5 billion gallons of water or an average of 6 mgd has gone into the Pit since MR suspended operations. An average of 3.4 mgd of this total was from the underground workings and storm water flow. An average of 2.6 mgd of this total was from the Horseshoe Bend discharge.

Q: How much water will go into the Pit once mining operations resume completely and the water treatment facility is operating?
A: The Horseshoe Bend drainage flow will be treated in the new treatment plant, and presently, this water will be entirely consumed in the mining operations. The remaining 3.4 mgd of flow from the underground workings and storm water flow will still flow into the Pit contributing to the rising level there. Eventually, when the water level approaches 5,410′ above sea level (expected about 2018), water will have to be pumped from the Berkeley Pit and treated at the Horseshoe Bend facility. Having the plant in place provides assurance that the capability is there when it becomes necessary to treat Pit water.

Q: Where will the treated water go?
A: Current plans are to treat the entire Horseshoe Bend drainage flow at the treatment plant, and then route all of the treated water to the concentrator for use in mine operations. As a result, and for as long as the treated water is used in the mining circuit, there will be no discharge off-site. In the event the mine was to suspend operations again, Horseshoe Bend drainage water would be treated to discharge standards at the plant. Then it would be transported by a pipeline, being constructed along the historic Silver Bow Creek channel (Metro Storm Drain), to its confluence with Blacktail Creek, just west of the Visitor’s Center on George Street in Butte, Montana.

Leave a Reply


*