Wisconsin Resources Protection Council

Dear Editor,

On Jan. 25, a 40-year-old, 280-foot-high tailings dam in Brazil failed, releasing almost 12 million cubic meters of mine waste. Tailings dams are large structures containing wastes 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 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.

The spill flooded homes, submerging cars and buses under a river of sludge, resulting in 65 fatalities and leaving an estimated 300 people still missing, according to rescue workers. This accident occurred in a technologically-advanced country with a history of mining and with a mining company that has the financial ability to use state-of-the-art technology to construct and maintain tailings dams.

Aquila’s revised mine permit application minimizes the possibility of a tailings dam failure at the Back Forty project but doesn’t recognize the risks to people and water quality from the prevailing design of tailings dams that have caused dams to become progressively dangerous as their height increases.

Despite Aquila’s claim 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. 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 which isn’t 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 contracted with the CSP2 for a scientific review of Aquila’s tailings dam design.

Al Gedicks

Executive secretary of the Wisconsin Resources Protection Council in La Crosse, Wis.