The recent collapse of a mine tailings dam in southeastern Brazil has already resulted in 134 fatalities, leaving an estimated 300 people still missing, according to rescue workers.
The spill flooded nearby homes, submerging cars and buses under a river of reddish-brown sludge. This environmental disaster should raise red flags for Michigan regulators and the communities downstream from Aquila Resources’ proposed open-pit metallic sulfide mine and tailings dam next to the Menominee River on the Wisconsin-Michigan border.
On Jan. 25, a 40-year-old, 280-foot high tailings dam failed in Brumadinho, Brazil, releasing almost 12 million cubic meters of mine waste.
The dam is owned by the mining giant Vale, the same company responsible for a tailings dam failure three years earlier in Mariana that buried three 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.
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.
The Brazilian tailings dam that failed was built in 1976 using the “upstream” dam construction method, which is considered the riskiest method of dam construction.
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Upstream dam construction has a track record of causing dam collapses around the world, including the catastrophic Mount Polley tailings dam collapse in Canada in August 2014, the largest environmental disaster in Canada’s mining history.
This failed upstream dam construction method is now being proposed for Aquila’s tailings dam at the Back Forty project next to the Menominee River which eventually drains into Lake Michigan, providing drinking water to millions in the Upper Midwest.
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 found that 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.” The documentation is on the Minnesota DNR site.
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. Whether it is 5.1 or 4.9 million cubic meters, the large volume of tailings poses a serious risk for a tailings dam failure that is not addressed in the 900 pages of Aquila’s revised permit.
To address this regulatory failure, the Front 40 Environmental Group and the Mining Action Group of the Upper Peninsula Environmental Coalition have just contracted with the Center for Science in Public Participation for a scientific review of Aquila’s tailings dam design.