You are the owner of this article.
editor's pick

Getting the Berkeley Pit under control: Pumping treated water could start as soon as March

  • 0
  • 5 min to read

Montana Resources and Atlantic Richfield Company won't have the Berkeley Pit pilot project in time for Christmas this year, but the project is not that far off the originally predicted mark.

Likely to be flowing by March, that puts it four years ahead of schedule instead of five. But that is still plenty of time to begin testing the treatment of the pit’s water, say mine officials.

A 900-foot hole beneath the water’s surface, the Berkeley Pit is one of the larger contaminated water bodies in the U.S. and is only one relatively small part of the largest Superfund complex in the nation. It began slowly filling up with metal-laden acidic water in 1982. That’s when Atlantic Richfield could no longer afford to mine copper in the Richest Hill on Earth and cut power to the pumps that held groundwater at bay. The water has been rising in the former copper mine since then.

The project is a complex web of pipes that will circulate the toxic water around the mining operation with pit stops at various treating facilities.

It is a project aimed to harness what many in Butte fear — 50 billion gallons of contaminated water.

But while the news of the pilot project brought smiles for many earlier this year, it may muddy the water when it comes to Restore Our Creek Coalition’s vision of a free-flowing, meandering creek to slice through the midst of the 120-acre park Atlantic Richfield Company is offering to build for Butte.

Mark Thompson, MR vice president for environmental affairs, has often said publicly that MR supports the concept of the treated waste water to be released at Texas Avenue. If that were to happen, the coalition’s dream of a man-made creek to replace what once flowed through that part of southwest Montana before miners arrived would be one more step toward realization.

The current plan is for the treated water to exit out of an underground pipe already built to deposit the water into Silver Bow Creek at George Street.

But one of the things the mine will consider as it treats and tests pit water is if the companies will need to discharge the treated water at all.

It’s possible all of it could be used for the mine’s workings.

“One of the answers we’re hoping to get from this project is what kind of volume of discharge would be anticipated in the future,” Thompson said.

But Northey Tretheway, spokesperson for the coalition, says that plan does not conflict with his group’s vision.

“The mine won’t be there forever,” Tretheway said. “We’d like it to be, but when it’s not there, where‘s it (the water) going? Instead of being short sighted, we’re looking down the road a ways. When it’s gone, we want this restored the correct way.”

MR’s permit is expected to keep it sailing up to 2031, but ore deposits indicate the company has the potential to glide right on through that designated stop sign.

A grand experiment

There are, at this point, still a lot of unknowns with the pit. The mine has talked about putting tailings — blasted rock exhausted of copper and molybdenum and mixed with water that’s been put through the mill (literally) — directly into the pit rather than the Yankee Doodle tailings pond, where it now goes.

But if that happens at all, it and the debate it would likely generate would be very far into the future, Thompson said. The companies have modeled for a lot of eventualities, but not for that one yet.

Next year, MR and Atlantic Richfield’s engineers will begin to find out what parts of their modeling they have done that will bear fruit.

One thing the companies don't know for sure is whether the water will wind up with too much calcium in it when it reaches the creek. Too much calcium in the water when it hits the waterway could form a coating in the creek bed.

If that happens, it would wash away, Thompson said.

Small-scale laboratory testing with actual creek water shows it won't occur. That fact gave Thompson enough confidence to say it wouldn't form the coating when asked about it last spring. But only real-world experimentation will tell the miners for sure that it won’t.

The Environmental Protection Agency, which has authority over the pit through Superfund, says the companies will have to demonstrate the project doesn’t harm the environment and meets water quality standards before any water is released to Silver Bow Creek.

Other lessons

You have free articles remaining.

Become a Member

You're out of free articles
Sign in or create a FREE account to keep reading.

Another unknown is exactly what will happen to Silver Lake water. MR has a contract with the county that allows for industrial use.

“There may be opportunity to replace some of our Silver Lake water usage with treated pit water, or not. That’s one of the reasons to run this pilot,” Thompson said.

But even if the mine doesn’t need to use as much Silver Lake water on a daily basis as it does now, MR would still need to maintain its contract with the county, Thompson said. MR has the right to put in a call for 18 million gallons a day if there is “an upset” the company didn’t plan for.

He said it’s likely the mine will continue to need some Silver Lake water on a regular basis because it's soft water. Treated water comes out hard.

“This whole thing is one giant test,” Thompson said.

Taming the beast

Another benefit of the pilot is to begin pumping and treating the water so it remains below the critical water level. The agencies set that water mark — 5,410 feet — as the no-turning-back point where the companies have to tame the beast that’s been slowly growing on the east side of town for decades.

Maintaining the water mark below 5,410 feet creates room within the pit. If the Horseshoe Bend Water Treatment Plant, where lime will be added to “drop” metals out of the metal-laden water, has to be turned off for maintenance or repair, the lake lying below will remain placidly calm and below where it needs to be to keep the residents of Butte from sweating with worry.

“We’re going to discover things,” Thompson said. “We don’t want to discover things we don’t know when it’s at the critical water level. We want to find out now.”

Also ramping up the project ahead of schedule means the companies can see how dry years versus wet years and other weather changes could affect their efforts at keeping the pit under control.

One thing the responsible parties will evaluate is flow. At some unknown point in the future, the responsible parties will test to see if the web of pipe and treatment checkpoints will be able to handle 10 million gallons of water a day — instead of approximately 7.5 million a day — as planned.

That would put 15.5 cubic feet per second (cfs) into Silver Bow Creek.

“We have to make sure we’re good at 3 (million gallons a day), good at 7 (million gallons a day),” Thompson said. “We have to make sure we can walk before we can run. We have to test the capability.”

Both EPA and Thompson say the water will be monitored every hour every day with samples shipping out to a laboratory on a daily basis.

Ultimately, the pilot project is testing the remedy the agencies and companies agreed to 16 years ago. Though unpopular with many residents, that remedy so far appears to be working.

Once the pumps were turned off, water needed to fill the underground tunnels that wend all around Uptown to protect the town, said Thompson. With the pit already collecting water, that was the primary reason to let it continue.

“Exposure to oxygen and water not only generates acid, it weakens the rock that is supporting the town (Uptown). By saturating the underground mine workings (below Uptown), it preserves the structural integrity that is holding up Butte,” Thompson said.

More water means less oxygen gets to the acid-generating rock. That makes the pit water less acidic.

According to Gary Icopini, geochemist for the Bureau of Mines and Geology, the pit water has a higher pH now — meaning it’s less acidic than it used to be. The Bureau regularly samples pit water.

The water’s balance is now 4.1.

Ten years ago it was in the low 3’s, Thompson said previously. Icopini said the normal pH of streams is anywhere from 6.5 to 8.5.

Atlantic Richfield declined to comment on the project other than to point to a news release the company issued in September which said the polishing plant would be complete in mid-2019. It is still under construction.

“Nothing to add — the project continues on schedule,” said Michael Abendhoff, spokesperson for Denver-based BP, the parent company of Atlantic Richfield. BP moved its headquarters from Houston to Denver recently.

Thompson said the mine doesn’t have to wait for the last brick to be placed on the polishing plant to get started. He thinks enough of it will be built by March that workers can push back their sleeves and, with wet spring mud on their boots, begin to figure out what it'll take to tame the beast.

Subscribe to Daily Headlines

* I understand and agree that registration on or use of this site constitutes agreement to its user agreement and privacy policy.

Load comments

Get up-to-the-minute news sent straight to your device.


News Alerts

Breaking News