With a $19 million price tag attached, Atlantic Richfield Company prepares to discharge mine waste water from its brand new polishing plant into Silver Bow Creek, said Ron Halsey, operations manager.
But that won’t get started until sometime in September, he said.
This means another delay, but the two companies are still four years ahead of the schedule originally laid out by the Environmental Protection Agency years ago.
Mark Thompson, Montana Resources vice president for environmental affairs, declined to say how much MR has spent on its part of the Berkeley Pit pilot project. He did say “it’s in the millions.” He said it’s less than Atlantic Richfield’s expenditure.
Halsey led a tour for the local press Tuesday of the new plant. He said the company is proud of it.
The plant, located off Shields Avenue just east of the Berkeley Pit viewing stand, will not see pit water flow through its shiny new metal pipes. Instead, the water that comes into the polishing plant will, technically speaking, come from the mine's waste repository, Yankee Doodle Tailings Impoundment.
The corrosive pit water will first go through MR’s copper recovery cells, then route through a network of 24-inch black pipe creating a spaghetti junction around the mine, with stops at Horseshoe Bend Water Treatment Plant and the mill circuit before landing on the “beach,” at the impoundment. The beach looks like about a mile of brown mud several hundred feet above the town.
At the tailings impoundment, the water separates from the brown muck and drains to the relatively clear water pond to the north.
Pipes will then carry water from the mostly clear pond on the north end of the impoundment to the polishing plant.
The plant will then run the water through filters of sand, gravel and coal to capture the solid stuff still lurking in the flow. Some water could go through a reverse osmosis system. Automatic monitoring can shut valves and divert water into a pipe, sending it back to MR’s mining operation, if the water is not at the correct level of compliance when it enters the final pit stop.
Halsey said the plant will start with five or six full-time employees and will be manned 24-7. But in time, that work schedule will be reduced to a more normal business operation structure.
Halsey said the workers will be equipped with a pager system and an alarm will alert workers if something goes wrong at the plant.
Today the pit holds close to 50 billion gallons of toxic water that's been collecting since Atlantic Richfield turned off the groundwater pumps in 1982. The Anaconda Mining Company established the pit to mine copper starting in 1955. Atlantic Richfield bought the mining company in 1977.
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The “brains” of the plant, a monitor box, shows the pH and the turbidity of the water. Halsey said that the water is currently coming into the plant at a pH of 10. Before it can leave the plant, the water has to drop to a pH of 7.
Water enters the plant from the tailings impoundment while Atlantic Richfield gets ready for its impending four-week EPA review. But because the plant is not yet ready to discharge, the flow coming in is sent back out into the mine after polishing, rather than heading to the creek.
The plant has room to grow, said Tim Hilmo, Atlantic Richfield project manager. He said the reverse osmosis system will be used if there is a need for more aggressive polishing. He said that could be "years" out. He also said it could be a need dictated by the seasons. He said the company could install more reverse osmosis systems down the road.
"There could be new technology," Hilmo said. "It's a large facility for the unknowns."
Halsey said the biggest challenges for the plant, once it’s fully up and running, will be the changing water chemistry.
“That and the volume,” Halsey said.
The pilot project is to run for two to four years and the amount discharged can change. Sending 3 million gallons a day will keep the pit at its current level. But the system can handle up to 10 million gallons a day, Halsey said.
The EPA established 2023 as the date when the surrounding mine shafts would reach the critical water level. When that moment happened, the companies were supposed to be ready to start pumping and treating pit water forever.
But MR announced the pilot project in early 2018, with the initial plan that it could be fully functioning by the end of last year. It will enable the two companies, who are responsible for the pit's "dirty water," to show that they can control the pit and can maintain the water level so it does not rise.
The news of the pilot project was heralded as resoundingly positive. Many have long feared the pit and the potential for it to grow above the critical water level and enter into the groundwater system despite oft-repeated assurances from officials that such a scenario would never happen.
The pilot project does not preclude Atlantic Richfield's proposed new water treatment plant, which the former oil company is offering as a way to draw down the pit to possibly as much as 150 feet. Hilmo said there are still a lot of unknowns on that and the parties and agencies are still discussing it.
Atlantic Richfield wants to draw down the pit in the event the earthen dam holding the impoundment should ever breach. The pit could "catch" tailings if it is not full of water.
Halsey said the underground pipe that will be the conduit for the pit water at the confluence on George Street is ready. But, he said, there is some construction left to do at the discharge point.