Changes coming to facility tailings disposal site
MARQUETTE — A few changes are planned for operations related to the Eagle Mine in Michigamme Township.
An update on the nickel and copper mine was given to the public Monday at the Eagle Mine Information Center, located at 153 W. Washington St., in downtown Marquette.
Amanda Zeidler, health, safety and environmental manager for Eagle Mine, talked about the Humboldt Tailings Disposal Facility at the Humboldt Mill. According to eaglemine.com, tailings are sent from the mill, located in Humboldt Township, to the facility where Eagle will place about 75 feet of tailings into the pit, leaving around 120 feet of water between the sulfide-bearing tailings and the surface. The facility also contains 200 feet of tailings from the old Ropes Gold Mine.
“Our tailings are disposed at the bottom of the tailings pit, subaqueously,” Zeidler said.
The top portion of the pit, she said, is “pretty clean water” that’s mostly precipitation and runoff, with the water chemistry at the lower part of the pit not as good because that’s where processed water and tailings are disposed.
The middle section — the chemocline — is where the chemistry changes a bit, she said.
“So, the water isn’t quite as clean, isn’t quite as good, at this point down,” Zeidler said.
Currently, the mill and the water treatment plant located near the pit take water from the cleaner top surface, treat it and discharge it into nearby wetlands, she said.
“As we continue to add tailings and processed water to the pit, this chemocline is actually moving up,” Zeidler said. “So, as it moves up, there’s more chance of it to turn over.”
Turning over can take place during windy days, for instance.
“If it turns, that means some of this dirty water will be moved up to the top layer,” Zeidler said. “So, what we want to do is try to stop that from happening.”
At the water treatment plant, she noted Eagle is going to start treating the dirty water from below, while the mill too will begin taking processed water from lower down.
Since Eagle won’t use this clean water anymore, that cleaner layer in the pit should get bigger and the dirtier water should lessen because it will be treated, said Zeidler, who pointed out changes also are planned for the water treatment process.
“Since we’re taking some of this dirtier water, we have to add a couple of treatment steps to it,” Zeidler said.
Eagle also is seeking a permit from the Michigan Department of Environmental Quality to discharge directly to the Escanaba River.
“What that allows us to do is it gives us more operational flexibility,” Zeidler said. “When you discharge directly to the wetland, it’s a pretty stagnant area. There’s not a lot of mixing, and if we discharge directly to the river, that will give us some mixing, a little more mixing ability.”
Eagle currently is discharging into the wetlands and keeping them “wet and alive,” she said.
“If we take away the discharge to the wetlands, we’re going to have to come up with a way to keep those wet,” Zeidler said.
Eagle is installing an intake pipe that, according to Zeidler, will pull the water from the river and bring it back to two discharge points, and that water will be distributed through the wetland area.
A free presentation about water quality at the Humboldt Tailings Disposal Facility is scheduled for 1 to 5 p.m. Nov. 15 in the Huron Room of the University Center at Northern Michigan University.
Devin Castendyk, Ph.D., a pit-like specialist from Denver who is a consultant for Hatch Associates, will give the presentation entitled “The Continuing Evolution of the Humboldt Pit: from open pit mine to flooded pit to tailings disposal facility to integrated watershed.”
Zeidler also discussed Eagle’s proposal for the extraction of the Eagle East ore body, located about 1.2 miles east of Eagle Mine in Michigamme Township. She anticipates a final decision for the permit from the DEQ in December.
Meagen Morrison, Eagle Mine social responsibility adviser, said that about a year ago the company began digging a tunnel to get to Eagle East.
Timing was a factor, as was financial viability.
“With Eagle, we want the ending of Eagle and the beginning of Eagle East to happen around the same time,” Morrison said. “It wouldn’t make sense for us to start Eagle East, you know, two years after the end of Eagle.”
Morrison also discussed Eagle Mine’s safety record from Jan. 1 through the end of September.
She said there were five medical aid injuries: an eye abrasion, two bee stings, a caught finger and a sprained ankle.
A “near miss” incident took place in an aggregate storage building in which a loader and a haul truck between the drivers collided, although no one was injured.
What they had, Morrison said, was a failure to communicate.
“So those are the incidents that we want to track, see why they occurred and what we can do to prevent something like that from happening again in the future,” Morrison said.
This summer, a haul truck was traveling on Marquette County Road 550 when a tire went flat, with the driver having to find a straight spot along the road to pull over, she said. Unfortunately, that spot had soft soil, and the side of the truck sank into the soil. Eventually, the truck was pulled out, but in the meantime, it was blocking a lane.
Morrison said that incident was a reminder to drivers to be aware of haul trucks and larger vehicles in general.
“Don’t assume that they can see you just because you can see them,” Morrison said.
Also, on Sept. 27 Eagle Mine passed the one-year mark of having no lost-time injuries, which result in employees losing time at work, she said.
Eagle Mine is a subsidiary of Lundin Mining Corp.
Christie Bleck can be reached at 906-228-2500, ext. 250. Her email address is email@example.com.