White Pine Mine tailings pond disappearing, still inspected as dam
While it comes as a surprise to some, the state of Michigan still requires the registration and inspection of the human-made tailings ponds at the White Pine Mine. This makes the Tailings Pond No. 2 dam the longest in Copper Country. It is 5.5 miles long, and ranges in height up to 70 feet, according to records held by the Michigan Department of Environment, Great Lakes, and Energy. The pond is the northernmost of three to the northeast of White Pine, and the dam surrounds the west, north and east sides. It drains into Perch Creek through a series of stilling ponds.
Hearing the dam carried a ‘significant hazard potential’ with EGLE surprised Michael Kocher, the Ontonagon County Emergency Services Director.
“There are no inhabited residences anywhere north of those tailings ponds until you get north of highway 64,” Kocher said.
He said there are thousands of acres of woodland between the ponds and M 64.
Kocher thinks there is little risk from what remains of the tailings pond, but contacted the dam owners for an emergency action plan.
He said they provided one two-inches thick, which has been added to the ones he holds for the UPPCO dams in the county. They will also participate together in future “tabletop games”; theoretical exercises to test their preparedness for a variety of disasters.
According to the most recent inspection filed with EGLE, the tailings ponds at White Pine Mine were built in the late 1960s and began accepting tailings from the mine in 1970. They designed the dam to hold 270 million tons of tailings, but collected a third of that before mining operations ceased in the early 1990s. The dam, which was being built up from local materials as the tailings level rose, only reached about 60% of its original design height.
Since then, the water level in the pond has decreased. The owners have pursued a multi-year closure plan that includes revegetation of the surface of the pond.
“They only hold one-tenth of the water they used to,” Kocher said.
Still, engineers inspect the dam and file reports with EGLE every four years. According to both Kocher and the EGLE reports, a mine employee also still does a weekly “windshield” inspection, looking for signs of erosion or damage and noting the level of the water.
The state-filed inspections have found minor issues with erosion and animal burrowing, as well as some maintenance issues with a spillway. The owners promptly repaired the spillway and a follow-up report with photographs was filed with EGLE. Erosion and animal burrowing along the length of the dam has also been remedied and is part of the weekly monitoring.
EGLE inspects state-owned dams themselves, and municipality-owned dams by request. Private dam owners are responsible for hiring a licensed engineer to do inspections on their dams and submit them to EGLE.
Dan DeVaun is one of the three inspectors with EGLE that reviews the inspections submitted by private dam owners. His territory covers the entire Upper Peninsula and the northern half of the lower peninsula.
“Unfortunately, we’re grossly understaffed,” DeVaun said in August.
The dam inspection program has been under review since the Edenville and Sanford dam failures earlier this year, and they are expecting the addition of at least one more inspector to the team.
DeVaun said that while failures as large as Edenville and Sanford are not common, EGLE does usually see a couple dam failures each year. Usually they’re smaller dams with very little impact, while EGLE’s compliance enforcement focuses on dams that carry a risk of danger to the public if they fail.
“Even if it’s a low-risk situation, we’re still going to engage with the owner,” DeVaun said.
In that case, he said it would entail more attempts at helping the owner make repairs rather than a high-priority enforcement action. After safety, economic and environmental concerns decide which dams get attention. DeVaun said it’s kind of a triage situation.
“We want to keep all of them safe and stable, but there’s different levels of concern,” DeVaun said.
Dam owners are financially responsible for repairs and maintenance to their dams. DeVaun says EGLE has found presenting fines for non-compliance to be counterproductive, since it can negatively impact an owner’s ability to pay for the repair work.
“We try to avoid enforcement actions as much as we can and instead try to pursue working with them to get them into compliance,” he said.
He cited an example in Chippewa County where a valve had failed and a reservoir drained. While there was little-to-no damage, the owners could have been hit with fines by EGLE. Rather than do that, DeVaun said they worked with the owners. EGLE helped them find an engineer and permit the work to get the valve fixed as quickly as possible.
DeVaun said the risk with a tailings pond is more structural than hydrologic.
“In terms of overtopping or flood control, it’s usually not as much of an issue with a tailings dam,” he said.
With no river flowing into it, even heavy rainfall doesn’t have a dramatic impact on the reservoir.
“It’s got storage for ages,” DeVaun said.
During inspections of a tailings dam, they mainly look for erosion, animal burrows, or other signs the dam is compromised. Beyond visual inspection and surveyor’s measurment tools, they also use piezometers built into the dam. Piezometers measure ground water, to make sure it doesn’t get so high or start moving so quickly that it destabilizes the dam.
The mine owners, Copper Range Company, could not be contacted, and Highland Copper Company, who currently has a “right to acquire” arrangement according to their website, did not return requests for comment.