MARQUETTE COUNTY, MI-- Environmental groups say a collapse at the Eagle Mine last year points to its instability, but mine officials are disputing that claim.
Kathleen Heideman is a board member of the Upper Peninsula Environmental Coalition. She says a report by the Mine Safety and Health Administration obtained through the Freedom of Information Act called the August event “significant,” as at least 50 feet of rock fell.
It apparently happened in an excavated portion of the mine—known as a stope—after a blast in a different part of the mine.
Just beforehand workers had been in the stope installing rock bolts and cables to keep the roof up. Heideman says a number of difficult-to-detect micro-flaws runs through the ore body, and the MSHA report indicated cabling that supported the stope roofs was inadequate.
“They can’t predict, apparently, the presence of these failure points,” she says. “They had monitored around the stope when they were working and MSHA said that they were not able to detect it and that those failure points could be encountered at any time.”
Heideman says the concern all along from the environmental perspective is the protection of the Salmon Trout River.
“They’re starting lower in the mine and working their way up and they are getting closer and closer to the top of the mine as they go. And just above the top of the mine is the Salmon Trout River. The prediction in the beginning was that if this rock is unstable there could be a catastrophic collapse at the headwaters of the Salmon Trout River,” she says.
Matt Johnson is External Affairs Manager for Eagle Mine. He says the event wasn’t a collapse but a “fall of
ground”—considered to be more localized and much smaller than a collapse.
“The fall of ground occurred on a stope that we wanted to fall, since it was ore,” he says. “A collapse would be considered something that has to do with an access tunnel to the mine, the roof of the mine, or the crown pillar of the mine, which it was not. And so the fall of ground that Eagle experienced has nothing to do with the stability of the mine, the roof, or the crown pillar of the mine.”
Johnson notes regulators and the MSHA were immediately contacted, but the fall wasn’t large enough to require public notification.
He says while the rock fall was unplanned, the mine continues to be stable.
“The stability of the mine is a separate issue than the fall of ground. The stability of the mine is something that we look at and monitor on a daily basis with seismic monitors. We have many years of rock stability data to ensure the stability of the mine during our operation,” he says.
An informational meeting on the potential Eagle East Mine, approximately eight kilometers from Eagle Mine, will be held Thursday at 5:30 p.m. at Westwood High School in Ishpeming Township.