LADYSMITH, Wis.— Since the Flambeau Mine, located just outside this small northwestern Wisconsin community, closed in 1997, it has served as a kind of Rorschach test for both supporters and opponents of sulfide-based mining in and around the Great Lakes.
Here in northeastern Minnesota, supporters of the proposed NorthMet and Twin Metals copper-nickel mine proposals, regularly cite the Flambeau Mine, built by Rio Tinto/Kennecott subsidiary Flambeau Mining Co., as an example of a sulfide-based deposit that was successfully mined and closed without polluting ground or surface water. Considering the likelihood that these proposals could gain new traction under the Trump administration and given that Foth Engineering, the firm that conducted much of the engineering for the Flambeau Mine, is involved with others in northeastern Minnesota, it’s worth examining those claims.
To the Flambeau Mining Co., which completed reclamation of the copper and gold mine in 1999, there is little question that the company met its obligations under the regulations established by the Wisconsin Department of Natural Resources.
“Flambeau Reclaimed, promises made, promises kept” is part of the logo now used on the company’s letterhead, which continues to sample and test groundwater twice a year from about 20 monitoring wells located in and around the former mine pit. According to a statement from Rio Tinto, those tests “show conclusively that ground water quality surrounding the [mine] site is as good as it was before mining.”
Yet, the term “surrounding the mine site” seems to be an important qualifier in that Rio Tinto statement. In fact, there is no evidence that the company has failed to meet groundwater standards outside of a designated “compliance boundary” that extends roughly a quarter mile out from the perimeter of the former mine pit.
Yet, as mine critics point out, within both the backfilled mine pit as well as some test wells located near the former pit (but within the compliance boundary), the company’s own test data shows clear and substantial contamination from a variety of heavy metals, including arsenic and manganese, at levels far above those found prior to mining and well above water quality standards.
According to the 1990 Environmental Impact Statement completed by the Wisconsin DNR, private water supply wells near the mine averaged 1.5 parts per billion (ppb) of arsenic and 217 ppb of manganese prior to the opening of the mine. Yet water quality tests conducted by the company as recently as last November show arsenic levels in test wells within the former pit as high as 24-32 ppb and manganese levels as high as 27,800 ppb in a shallow well, far in excess of the public health standard of 300 ppb.
And while contaminant readings are higher within the pit itself than anywhere else, two test wells located between the former pit and the Flambeau River showed arsenic levels in testing last fall ranging from 19.4 to 12.1 ppb and manganese levels ranging from 85.7 to 1,750 ppb.
The mine itself was in a sensitive location, just 140 feet from the edge of the Flambeau River, which is why the mine proved controversial when Kennecott originally proposed to build the facility in the early 1970s. That proposal prompted Wisconsin to update its mining regulations and the Flambeau Mine was the first and, so far, only, mine approved in the state since the new rules were put into effect. It was only later, in the early 1990s, that the proposed mine moved forward and as part of its closure plan, the company proposed to build a dam on the pit’s southwest end, which lay closest to the Flambeau River. It’s that dam that appears to have allowed some contaminants to migrate from the pit to the surrounding groundwater very close to the river.
“It is moving out, it’s just a matter of how quickly it’s moving out,” said David Chambers, a geophysicist with 45 years of experience in mineral exploration and development. Chambers is also the founder and president of the Center for Science in Public Participation, which provides technical advice and support to grassroots organizations working on mining related issues.
At the same time, it’s notable that the level of manganese contamination within the mine pit itself appears to be declining slowly but steadily from the peaks seen in the years immediately after the company backfilled the mine pit with a combination of waste rock and limestone. At the same time, arsenic levels appear to be rising. Chambers said the generating of metals will continue at the site for years based on the well-known process when sulfide-based ore is exposed to air and water.
Despite the level of contaminants found in the groundwater near the river, it isn’t clear that it is affecting the river itself. The Flambeau is only about five feet deep in the vicinity and its connection to groundwater in that location is uncertain. “Some contaminants are probably going under the river,” said Chambers. “They may be impacting [private] wells on the other side.”
Laura Gauger, a Duluth resident and activist who has written a book about the Flambeau Mine, said the possible contamination of private drinking wells located on the opposite side of the river is one of her biggest concerns, but it’s one that may never be answered. “There are no test wells on the other side of the river, so there’s no monitoring,” Gauger noted.
It’s not the only example where lack of monitoring could be working to the advantage of the mining company. In addition to groundwater near the former pit, a small adjacent stream, known as Stream C, is now listed as impaired by the Wisconsin DNR due to high levels of copper. “Both the mining company and the state of Wisconsin are taking the position that it’s a little stream, so it’s not a big deal,” said Chambers, who has examined the stream in question. He believes that the surface contamination is coming from fugitive copper dust left over from a former ore loading dock at the mine that likely created dust during loading operations. That metal-containing dust appears to be slowly migrating into the stream.
Chambers acknowledges that the levels and the volume of metals being discharged in the stream aren’t extraordinary, but he notes that a monitoring station on the Flambeau River, located immediately downstream of Stream C, has been discontinued. “I don’t think we have any case of egregious environmental harm, but if there is we wouldn’t know it,” said Chambers.
The Timberjay reached out to Wisconsin-based Foth Engineering, which designed the Flambeau Mine, for comment on the effectiveness of their operational and closure plans. The company did not respond prior to press time.
A case study for larger operations?
While the debate over the pollution impact of the Flambeau Mine is likely to continue for decades, the larger question is whether the former mine provides a relevant example that could help to illuminate the risks associated with proposed mines in northeastern Minnesota.
That appears tenuous at best. By the scale of the proposed Minnesota mines, the Flambeau Mine was tiny, with a 32-acre mine pit, created by the removal of a high-grade ore containing as much as ten percent copper and lesser percentages of gold, silver, and zinc. The mine’s total footprint, including associated surface buildings and related facilities, covered just 181 acres. After operating for four years, removing a total of 1.9 million tons of ore, the 8.6 million tons of waste rock was placed back in the pit and the site was revegetated and buildings removed, leaving a site that one would need to examine closely to determine it once contained a mine.
The Flambeau Mine left no tailings behind on the site since the ore was of such high grade that it was economical to ship it to Canada in raw form for processing.
By contrast, the deposits proposed for mining by NewRange Copper (formerly PolyMet) and Twin Metals mines are very low-grade— less than one percent copper, and the associated mining operations would be massive in scale compared to Flambeau, involving total footprints in the range of several thousand acres. Both would permanently leave hundreds of millions of tons of surface stockpiles of waste rock as well as tens of millions of tons of tailings from processing, leaving the potential for contamination for centuries. The original NorthMet proposal would directly impact over 900 acres of wetlands, compared to eight acres impacted by the Flambeau Mine.
Since both proposed northeastern Minnesota copper-nickel mines are currently in the process of revamping their mine plans, the specific details of each could change if and when new mine plans are issued.