Out of sight isn’t always out of mind, much like contamination from decades of mining in the Coeur D’Alene Mountains at Jack Waite Mine on the Montana-Idaho border.
Despite its remote location, toxic heavy metals from the mine’s past operations traveled downstream over time, creating sustainability problems for those living in the path. Hunters, small-business miners and recreation seekers also visited the site, potentially encountering contamination.
The mine tailings, or toxic remains when miners extracted valuable minerals and metals, included zinc, mercury, arsenic and lead. And since miners used the river system between 1911 and the 1960s to flush them out, it left nearby Tributary Creek sterile while affecting other water bodies.
The project’s goals mirrored the USACE sustainability mission to create and maintain conditions where humans and nature can exist in productive harmony.
"Once metals such as zinc enter the water, it can potentially decimate aquatic life," said Rod Zion, U.S. Army Corps of Engineers, Seattle District, project engineer. "A major goal for the project was to restore the stream in hopes the aquatic life will move back into the area."
From 2007 to 2012, Seattle District officials worked to complete the multi-contract three-phase project to collect and contain onsite tailings and materials that contributed to the spreading contamination, said Zion.
Most people now understand the environmental consequences of these former practices and dangers sometimes present in abandoned mine sites.
However, some people are attracted to them for gold mining prospects while others used them as a "playground" for off-road vehicles, according to Zion. "People would stir up the tailings where they became more susceptible to transportation by wind and water."
Despite the need to clean up the remote location, Zion said there were numerous challenges, such as working with multiple agencies. The Corps worked closely with multiple contractors and stakeholders, the U.S. Forest Service and the Environmental Protection Agency.
Another challenge was the limited access and remoteness of the site. The Forest Service played a crucial role in helping the team develop access to the site, said Zion.
"The 15 miles of unimproved Forest Route roads leading to the site was overgrown with vegetation," said Zion, who said they worked closely with the USFS to fix the roads. "We needed a lot of heavy equipment on site and weren’t sure what road improvements were necessary for the multi-year project."
In addition, the mine is high in the mountains with a short construction season due to snow and ice accumulations. The Phase 3 contractor took full advantage of the available construction season by spending three weeks clearing nearly 15-foot deep snow from 15 miles of road along steep hills that bordered the road system.
They also faced challenges during contract execution.
At one point, an excavator sank into a slime-like material that had not been previously identified beneath the tailings when the contract was written.
"It’s a byproduct of the milling operation—it looked like blue clay in an undisturbed state, but as the excavator got to it, the vibration turned it to liquid, like a cornstarch slurry." said Zion "We realized we had a significant issue that wasn’t part of the contract. You couldn’t just pick it up and move it because it would liquefy and spill on the roads."
The necessary modifications delayed progress, adding to complications to an already short construction season.
Coordinating with the public was another challenge.
"The high volumes of massive articulated haul trucks are an enormous safety concern for people in the area," said Zion. "We coordinated with the USFS and installed an elaborate system of signage, gates, and vehicle escorts with prescribed times for the contractor’s safety officer to escort them through job site using mile markers while communicating via radio."
The out-of-sight project gained visibility when district leadership made the long trek to see how the finished product, despite all the obstacles, turned into an extreme success story for the Corps sustainability mission and for those affected by the mine’s toxins, Zion said.
"The excellent team work among stakeholders, contractors, and USACE enabled us to solve issues at the lowest levels. We appreciated their visit because it gave us a chance to showcase how we successfully managed a large, logistically complex project," he said. "On a project like this, I measure our success in two ways: if we achieve what our customer wanted and if we can meet the clean-up goals established for the project from an environmental perspective. This project did both."