A proposed expansion of the Stillwater Mine looks to extend the facility's life by up to 42 years by expanding the space for mining waste.
The amendment would build out tailings storage and allow for the disturbance of 28.6 acres within the Custer Gallatin National Forest and 109 acres of private land about seven miles northeast of the facility near Nye in the Stillwater River drainage.
For every 100 tons of ore like the palladium and platinum processed at the underground mine, there are about 99 tons of waste like rock, sand and silt produced. That waste often contains ammonia and nitrate from the use of explosives. The mine currently produces about 3,200 to 3,900 tons of minerals per day.
The current waste rock facility for the Stillwater Mine is expected to reach capacity by 2030. Depending upon approval, construction of the new storage area is expected to begin in 2029. Over 20 potential sites were analyzed for the expansion before Sibanye-Stillwater put forth an application in 2023. The Montana Department of Environmental Quality and the Custer Gallatin National Forest initiated a 30-day public comment period on Monday for a draft environmental impact statement associated with the expansion.
"This permitting effort is necessary for continued operation at the Stillwater Mine as it will enable the next planned phase of tailings and waste rock storage,” Heather McDowell, Sibanye-Stillwater legal and external affairs vice president, told the Gazette. “We have been working with a number of stakeholders on this plan for the next phase of waste storage for over 10 years, including Northern Plains Resource Council and its subsidiary, who are our counterparties under our Good Neighbor Agreement.”
The mine has been in operation since 1987. The Good Neighbor agreement, approved in 2000, holds the mining company to higher environmental and community standards than state and federal regulations require.
In advance of the expansion, Sibanye-Stillwater has proposed moving 2,500 feet of the lower section of Nye Creek below Pencil Falls. That would eventually result in relocating the creek away from chromite tailings and active mine areas. In the process, the mining company proposes to restore native vegetation to eventually improve the creek.
Trout ponds would also be filled as part of the proposal to eventually have the affected area reclaimed as wetlands and also reconnect Nye Creek to the Stillwater River fishery.
Sibanye-Stillwater has already held a few well-attended open houses on the expansion in advance of the public hearing. Still, members associated with the Good Neighbor Agreement worry about elements of the plan. A fact sheet shared by the group questioned the artificial means of creating the portion of Nye Creek, while also seeking further study on how the stream would be affected by varying flows. The sheet also recommended monitoring wells around where the tailings would be to detect any potential contamination and to improve the methods waste would be processed to reduce the likelihood of ground seepage.
“Although we have been involved throughout the planning process, the GNA does have some outstanding concerns with potential impacts associated with the proposed expansion," Katie Howes, Nye resident and chair of the Good Neighbor Agreement Task Force, said. "We plan to participate in the public comment period to raise these remaining questions and concerns with regulatory agencies. Our role in this expansion is a prime example of the importance of everyday people and companies coming together, collaborating, and finding innovative solutions to ensure development happens responsibly."
The expansion comes at a challenging time for Sibanye-Stillwater. While the price of palladium has improved somewhat since 2022, it’s still below the rate it was sold at years ago. The lower price has resulted in hundreds of layoffs by Stillwater County’s largest employer and the closure of the Stillwater West section of the mine.
“We are mining the highest grade palladium and platinum in the world and can continue mining for generations to come if we get the plan right now and the palladium market cooperates,” McDowell said. “We are looking decades ahead to try to get things right for our operations and our communities, and this next phase of tailings and waste rock storage is a necessary part of our plan.”
An open house will be held on Tuesday, July 7, from 4 p.m. to 7 p.m. at the Anipro Event Center in Absarokee. More information on the expansion and how to comment can be found at fs.usda.gov/r01/custergallatin/projects/archive/68998.