Brazilian Tailings Dam Disaster: Is Wisconsin Next?


By Christyam de Lima/Shutterstock.com

On January 25, 2019, a 28-story high tailings dam in Brumadinho, in southeastern Brazil failed, releasing almost 3 billion gallons of sludgy mine waste. The spill flooded nearby homes, submerging cars and buses under a river of reddish-brown sludge. The death toll so far has risen to 228 with an estimated 49 people still missing and presumed dead. This is Brazil’s deadliest-ever mining accident.

The same design for storing mine waste, known as the upstream dam construction method, is now being proposed for a large open pit metallic sulfide mine and tailings dam next to the Menominee River on the Wisconsin-Michigan border. While Brazil’s mining agency has already banned this design from further use, Michigan regulators are poised to approve this design and risk a catastrophic dam failure that could send toxic wastes into Lake Michigan and threaten drinking water for millions in the Upper Midwest. A coalition of concerned citizens, environmental groups and the Menominee Indian Tribe of Wisconsin is determined to prevent this from happening.

What are tailings dams?

Tailings dams are some of the largest human-made structures on earth. Tailings are the waste material left over from the crushing, grinding and chemical (including cyanide) processing of mineral ores. Tailings often contain residual minerals—including lead, mercury and arsenic that can be toxic if released to the environment. However, unlike water-retaining dams made of concrete and steel, tailings dams are held back by walls of sand and silt.

Contrary to the claims of safety by the mining industry, tailings dams are failing with increasing frequency and severity. When they fail, they can destroy entire communities and livelihoods. The largest mining disaster in Canadian history occurred in August 2014 when the Mount Polley tailings dam failed and released 6.6 billion gallons of tailings into the Fraser River watershed in British Columbia. Local emergency response officials warned downstream residents not to drink, cook with, bathe in or come in contact with the effluent.

The  Brazilian spill has contaminated 75 miles of the Paraopeba River, where mud, debris and dead fish have devastated the Pataxo indigenous people who depend upon the river for drinking, fishing and irrigation. A Pataxo woman emphasized that the damage from the spill was not limited to the loss of life and the pollution of the river. “Our relationship with the river is very special because the origin of the Pataxo was born in a drop of water that fell on the ground.”

The Brumadinho dam is owned by the mining giant Vale, the same company responsible for a tailings dam failure four years earlier at the Samarco mine in Mariana that buried 3 communities, killed 19 people, leaving hundreds homeless and contaminating hundreds of miles of river valleys with toxic sludge. It was one of the worst environmental disasters in Brazil’s history.

The tailings dam failures at Brumadinho and Mariana occurred in a technologically advanced country with a history of mining and with mining companies that had the ability to use state-of-the-art technology to construct and maintain tailings dams. Vale is the largest producer of iron ore and nickel in the world, with massive operations in Brazil. BHP Billiton was a co-owner, with Vale, of the failed tailings dam at Mariana.  BHP Billiton, an Anglo-Australian company, is the world’s largest mining company.

This environmental disaster should raise red flags for Michigan regulators who have already been besieged by multiple controversies about the impact of Aquila Resources’ Back Forty project on the communities and environment around this proposed mine. 

Aquila Resources’ Proposed “Back Forty” Mine and Tailings Dam

Aquila is a Canadian exploration company that has no experience with mining. It has recently submitted a revised permit application to Michigan’s Department of Environmental Quality (DEQ) for its proposed Back Forty metallic sulfide mine a mere 100 feet from the Menominee River. Although the Menominee River is an interstate waterway, the Wisconsin Department of Natural Resources has allowed Michigan to assume exclusive jurisdiction over the permitting process.

The proposed mine would produce 70 million tons of acid-producing waste rock and milled tailings. When sulfide minerals in mines and mining wastes are exposed to air and water, the chemical reaction produces sulfuric acid and metal pollution known as acid mine drainage (AMD). AMD is toxic to fish and wildlife due to dissolved metals and contaminants such as mercury, lead, arsenic, cadmium, zinc, copper and many others. These contaminants would threaten the Menominee River and eventually Lake Michigan, the second largest of the Great Lakes.

Downstream communities oppose the Back Forty project

The main revision to Aquila’s mine permit is the expansion of the tailings dam. Aquila claims that these 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. Downstream communities in Wisconsin that depend upon the river for their drinking water, fishing and tourism doubt the company’s assurances of safety. Seven counties, four towns, three cities, and dozens of tribal governments have passed resolutions against the project.

Mining on sacred lands?

The location of the proposed Back Forty mine has special significance for the Menominee Indian Tribe of Wisconsin because it is their original homeland. The Menominee River is named for the Menominee Indians, who trace their origin back thousands of years to when the Ancestral Bear emerged from the mouth of the Menominee River and was transformed into human form as the first Menominee. They occupied the Menominee River area for millennia, until an 1836 Treaty with the U.S. forced them to cede their original territory in Michigan. However, the Menominee Nation never gave up its right to protect its traditional cultural resources that are essential to their identity. The present-day Menominee reservation is 60 miles southwest of the proposed mine.

The mine site is located on the traditional lands of the Menominee Nation that include prehistoric burial mounds, village sites, raised agricultural beds and dance circles. Similar concerns about harm to water supplies and the destruction of sacred sites have resulted in massive tribal and environmental protest against the Dakota Access Pipeline next to the Standing Rock Sioux reservation in North Dakota.

Lessons of Brazilian Dam Failures for Michigan

The Brazilian tailings dam that failed was built in 1976 using the upstream dam construction method. This design involves piling waste from the mine toward the tailings pond, raising the dam to new levels as the dam grows in size. Upstream dam construction is the cheapest design because it requires less material to build. It is also the most prone to failure, according to experts. About 76 percent of tailings dam failures worldwide are related to upstream construction methods.

Upon hearing of the Brazilian dam failure, Menominee Nation community organizer, Guy Anahkwet Reiter said, “It hurts my heart to think that this could possibly happen to the Menominee River and the people depending on it to survive. Even more so that we as Menominee people who come from that river and have a connection that leads  back for thousands of years. The river holds memory, it knows our deep connection. The river is the center of our universe. We look to it to be reminded that we must always keep moving.” 

Can modern mining technology guarantee zero catastrophic events?

Aquila’s revised mine permit application minimizes the possibility of a tailings dam failure at the Back Forty project and fails to recognize the risks to people and water quality from a tailings dam design that has caused dams to become progressively dangerous as their height increases.

Despite Aquila’s claim that mining technology and regulation have made modern mining safer, a recent study by the Center for Science in Public Participation (CSP2) found nearly half of all recorded serious tailings dam failures happened in modern times, between 1990 and 2010. “These failures,” according to the report, “are a direct result of the increasing prevalence of tailings storage facilities with greater than a 5 million cubic meter total capacity necessitated by lower grades of ore and the higher volumes of ore production required to attain or expand a given tonnage of finished product” (https://files.dnr.state.mn.us/input/environmentalreview/polymet/request/exhibit3.pdf).

In Aquila’s original mine permit application, they proposed to store 5.1 million cubic meters of tailings. In their revised application, they propose to store 4.9 million cubic meters of tailings. If the open pit mine extends into an underground operation, as the company has told its investors, the volume of tailings will exceed 5 million cubic meters.

The stability of Aquila’s proposed tailings dam is at further risk because upstream embankments are not suited to areas of seismic activity because earthquakes can cause dam failures. Aquila’s mine permit application fails to mention that a small earthquake, called the “Menominee Crack” caused a split in the ground almost 360 feet long and 30 feet wide at its largest point not far from the mine site in 2010. Scientists from Michigan Technological University proposed that this seismic event, which they called a “pop up,” probably occurred “when underground pressure on the limestone rock in the area was released.” Could mining of the open pit and/or subsequent underground mining disrupt an area of trapped air pressure and lead to shifting rock layers that could destabilize the rock and soil underneath the tailings pond?

Regulators in the Michigan Department of Environmental Quality (DEQ) need to ask Aquila: “What would be the effect of a spontaneous 30 foot wide crack opening in the rock underneath the tailings pond?” Unfortunately, the leadership at the DEQ has shown little interest in raising technical and scientific objections that would delay Aquila’s rush to obtain all its required mine permits.

By Christyam de Lima/Shutterstock.com

Aquila’s wetland permit approved over objections of regulators

In June 2018 the Michigan DEQ issued Aquila’s wetland permit over the objections of DEQ’s own Water Resources Division. According to the agency’s Findings of Fact: “After due consideration of the permit application, on-site investigation and review of other pertinent materials, the Water Resources Division finds that the project does not demonstrate than an unacceptable disruption to the aquatic resources of the State will not occur and that the activities associated with the project are not consistent with the permitting criteria for an acceptable impact to the resources regulated under Parts 301, Inland Lakes and Streams, and Part 303, Wetlands Protection.”

Despite repeated requests from the public and environmental groups, the DEQ leadership has not provided an explanation of why the agency ignored the scientific and legal objections of their own agency staff.

Whatever the reason for the failure of the DEQ to enforce the wetland protection requirements of the Clean Water Act, it is clear that the DEQ has lost public confidence in their ability to critically evaluate Aquila’s tailings dam design. The Coalition to Save the Menominee River and the Menominee Indian Tribe of Wisconsin have both filed legal challenges to the DEQ’s approval of Aquila’s wetland permit in state administrative proceedings and in federal court.

It was precisely this lack of regulatory oversight that contributed to the Brazilian tailings dam disaster. According to an investigation by the Wall Street Journal, Vale executives knew for months that the dam was unstable and could collapse. Brazilian prosecutors are now seeking to hold Vale executives liable under anticorruption and environmental laws.

To address Michigan’s regulatory failure, the Front 40 Environmental Group and the Mining Action Group of the Upper Peninsula Environmental Coalition contracted with Dr. David Chambers, an internationally recognized expert on tailings dams and the director of CSP2, for an independent scientific review of Aquila’s mine waste storage plans. According to Dr. Chambers, “Any time tailings are used for structural support, the risk of failure is increased over that of mechanically engineered materials. It is not clear from the Dam Safety Permit Application…why the cost savings gained with upstream impoundment construction is more important than the increased long-term risk to the public of impoundment failure.” A far safer method, the downstream construction method, was never considered by Aquila.

As long as the mining industry ranks cost ahead of safety, the list of catastrophic dam failures will continue to grow, according to Chambers. The key question for Alan Septoff , communications director for Earthworks, an industry watchdog, is whether science or politics will guide mine permitting in Michigan. “In the wake of the 2014 Mount Polley mine waste disaster,” says Septoff, “ an independent panel of  mining experts from industry and academia recommended banning wet mine tailings disposal everywhere, and it’s that disposal process that has been at the root of subsequent disasters around the world. The Back Forty mine would use this inherently unsafe waste disposal, condemning those downstream to eternal threat of disaster because a mining waste impoundment must last literally forever.” 

Al Gedicks is the executive secretary of the Wisconsin Resources Protection Council in La Crosse. He is working with the Menominee water protectors to oppose the Back Forty mine project.