Michigan, Wisconsin Could Face Mining Disaster

The willingness of top Michigan regulators to ignore their own scientific staff and approve a wetland permit for a controversial open pit mine next to the Menominee River on the Michigan-Wisconsin border has been reported by Urban Milwaukee, but is only the beginning of a dangerous decision-making process. The proposed Back Forty metallic sulfide mine is owned by Aquila Resources, a Canadian exploration company that has no experience with mining.

Despite steadily increasing scientific evidence of the danger of a tailings dam failure next to the Menominee River and the potential catastrophic release of toxic mine waste into Lake Michigan, the Michigan Department of Environment, Great Lakes and Energy (EGLE) appears ready to approve the dam’s design. That design is associated with the January 2019 Brazilian tailings dam disaster that killed at least 250 people in Brazil’s deadliest-ever mining accident. Brazil has already banned this design from further use and ordered the decommissioning of 88 existing dams employing this design. Chile and Peru banned them earlier. The American International Group (AIG) has cut back the vast majority of its mining liability insurance in response to the Brazilian disaster.

The proposed construction method, known as upstream dam design, uses crushed waste rock and sandy soil – not steel and concrete – to build a retention dam for mine tailings, the waste material left over from the crushing and chemical processing of mineral ores like copper, zinc and gold. The upstream dam design is the lowest cost dam design but also the most prone to failure, according to experts. About 76 percent of the tailings dam failures worldwide are related to the upstream construction method.

Aquila and EGLE claim that the finely ground chemical-laden wastes, along with millions of gallons of water mixed in a slurry, can be stored safely next to the Menominee River in perpetuity. The proposed tailings dam would be 138 feet high. The total footprint of the tailings management facility (TMF) would cover 123 acres, the size of 100 football fields.

EGLE’s recent information flyer repeats Aquila’s claim that their TMF was specifically designed to reduce the known risks of traditional upstream dams. The walls of the dam would be constructed of crushed waste rock. The tailings themselves are at risk for liquefaction, a serious concern. Liquefaction occurs when the loose saturated tailing sands behave more like a liquid, flowing downhill and destroying everything in its path, as happened in the Brazilian disaster.

Aquila admits that 75 percent of the waste rock is expected to be potentially acid generating. This has raised a red flag for Dr. David Chambers, an internationally recognized expert on tailings dam failure who has been hired by local environmental groups to evaluate Aquila’s dam safety permit. Dr. Chambers has asked Michigan regulators: how will Aquila ensure that the embankment itself does not contribute to acid and metal leaching, causing the embankment to become unstable and liable to catastrophic failure?

Scott Dean, from EGLE’s Office of Public Information tells Urban Milwaukee that the treatment and containment plan for the TMF “incorporates proven measures to counteract or neutralize the acid-forming characteristics of the waste rock and tailings by the addition of limestone or by segregating waste rock types that have been determined to be non-acid generating for use in embankment development.” But the mining industry has yet to provide an example of where such “proven measures” have prevented acid mine drainage. Meanwhile, the U.S. Environmental Protection Agency warns that “potentially acid-generating waste rock is not suitable for embankment construction” because it can destabilize the structure and result in a breach in the tailings dam.

The structural weakness of the proposed tailings dam would be further exacerbated if Aquila increases the size of the tailings dam with additional mine waste from the company’s proposed underground mining after the open pit phase of the project. While the company’s permit application is only for an open pit mine, Aquila’s June 2019 quarterly report to investors states that “the evaluation of a potential underground mine option is ongoing.” Michigan regulators say that new permits would have to be approved if the company pursued underground mining, but once the open pit is already operating, the political pressure to approve the permits would be overwhelming, opponents argue.

The Mining Action Group of the Upper Peninsula Environmental Coalition said “We are alarmed by the applicant’s demonstrated history of contradictory and misleading statements concerning the Back Forty project’s ‘Life of Mine’ and the potential for underground mining. Why is a basic level of transparency not demanded in the EGLE permitting process?… Underground mining is clearly foreseeable and all impacts ought to be assessed now, rather than incrementally, in the future, drib by drab, effectively steamrolling the Environmental Impact Assessment process and avoiding any ‘cumulative’ calculation of impacts.”

The discrepancy between a seven-year open pit mine in Aquila’s permit application and the 16-year project with underground mining discussed in its investor statements has serious consequences for the tailings management facility because the design of the dam is “sized” to accommodate only the tailings waste produced by the seven-year open pit mine. This would necessitate increasing the height of the dam walls and the total volume of waste rock and water contained within the structure. Raising the tailings dam is a major risk factor for catastrophic dam collapse. The failed Brazilian dam was raised higher than originally designed, multiple times.

Scott Dean responds that EGLE’s Water Resources Division would review any plans to expand the mine “under the same Dam Safety criteria, which includes stability and protection of natural resources by any regulated dams.” Dean, however, did not explain why EGLE refuses to impose strict impoundment limits on the TMF so this dangerous expansion would not be permitted.

“It is not clear from the dam safety permit application,” says Dr. Chambers, “why the cost savings gained with upstream impoundment construction is more important than the increased long-term risk to the public of impoundment failure.”

Contrary to the claims of safety by Michigan mine regulators, tailings dams are failing with increasing frequency and severity. There have been 46 in the past 20 years. The reason is simple – the percentage of key metals in the excavated rock has been declining for decades. This necessitates ever larger mines to recover an ever smaller percentage of valuable minerals. The result has been a vast increase in waste rock and tailings. These structures can leak or collapse and are extremely vulnerable to extreme weather events in the era of global climate change.

At the June 25, 2019 public hearing on Aquila’s mine and dam safety permits held at the Stephenson, Michigan high school gym, the Menominee Indian Tribe of Wisconsin and local residents on both sides of the Menominee River told EGLE regulators that they opposed the use of what they viewed as unsafe and experimental technology. Guy Anahkwet Reiter, a Menominee tribal community organizer said “I don’t think Foth [Aquila’s consultant], Aquila or even EGLE have even considered the dam problem. I mean, I really don’t think that you have done your dam research or even have any dam knowledge. I feel this project creates too big of a dam problem. And for all those dam reasons, I can’t support this project that makes no dam sense.”

“If constructed,” says Scott Dean, “the TMF would be regulated as a high or significant hazard potential dam, including an emergency action plan for the dam.” While EGLE appreciates the public’s interest in what the environmental, social and economic impacts of a partial breach or total collapse of the tailings dam would be, he added, “EGLE does not have the statutory authority to require an applicant to conduct such an analysis.” However, under Michigan law, EGLE cannot issue a dam permit if the TMF will have a “significant adverse effect on public health, safety, welfare, property, or natural resources or the public trust in those natural resources.”

The last speaker at the public hearing was Dale Burie, president of the Coalition to SAVE the Menominee River, Inc. He said, “Tailings dams are a complex system that has evolved over the years. They are also unforgiving systems in terms of the number of things that have to go right. Tailings dams fail. I will guarantee it’ll happen. And you should be aware of this. The other thing: I know Mr. Trumble (an EGLE dam safety engineer) defends the design on this upstream dam. I just need to ask a question. Say you approve it, it goes in and it fails. Do you go to prison for lack of diligence of your duties? How are you folks held accountable?”

Al Gedicks is emeritus professor of environmental sociology at the University of Wisconsin-La Crosse and executive secretary of the Wisconsin Resources Protection Council.