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Using trees to remediate and stabilize mining waste


For decades, the Keweenaw Peninsula in the U.P. was home to more than 100 copper mines.

One of the byproducts of that is stamp sands, the practice of crushing rock and extracting heavy metals.

Remnants of it are still found throughout the peninsula.

Sitting at his desk at the U.S Forest Service’s Northern Research Station in Rhinelander, Ron Zalesny points to a satellite map of the Keweenaw Peninsula.

He’s focused in on Sand Point, an area of land along Lake Superior on the peninsula’s southeastern edge.

“This is where that Mass Mill was located and where they dumped everything. Then over time, it has gone into the lake and currents have pushed it here. This is Sand Point this point right here,” said Zalesny.

On the map, you can see a brownish-gray area along the shoreline indicating where the stamp sands have accumulated.

It’s a stark contrast to the blue Lake Superior and green foliage slightly inland.

“This is what's called the coastal wetland, this is just like a wetland. There's that healthy population of trees here. The problem is that that stamp sands is kind of encroaching on that coastal wetland,” he said.

While this will be a main area of focus for Zalesny for the next three years, it’s not the only area in the Keweenaw Peninsula to deal with stamps sands.

As WXPR has reported in a previous episode of The Stream, the mining waste has impacted land and water along the shores of Lake Superior.

It’s also impacting the way of life for the Keweenaw Bay Indian Community.

“The community members use this area. It's a highly valued recreation area. There are powwow grounds nearby and other culturally significant areas nearby. With the community using it and known pollutants in the soils that could have a potential concern for human health. But then also environmentally, in addition to just having heavy metals in the soils, with the stamp sands kind of moving inward, and potentially impacting these coastal wetlands, it also has the potential to cause damage to the waterways and existing vegetation. The trees and other herbaceous species that are out there now, and so it's kind of a two-fold thing,” said Zalesny.

Zalesny says the tribe has already done great work in remediating the mining waste. He showed before and after photos of the shoreline.

Vegetation is growing in contaminated areas where it previously couldn’t.

Now, Zalesny and other partners will be working with the tribe to continue that work and stabilize and take the heavy metals out of the soil.


To do that, they’ll be using trees, one of which is a specialized poplar tree.

“These trees are the result of decades of breeding, and testing, and selecting from various poplar breeding programs throughout the country. What we have done is partnered with universities and other organizations that did that breeding and have agreements where we can use and test that material,” said Zalesny. “We're subjecting them to these harsh conditions and then selecting the ones that can thrive in those harsh conditions. In this situation, ultimately, the ones that can actually take up those heavy metals.”

Zalesny says poplars are some of the best trees for this kind of work because of their extensive root systems, how quickly they can grow, and for what’s called hydraulic control potential or their water use.

While their main function is to remove the heavy metals from the soil, they’ll also be used to stabilize the area with the goal of preventing the stamp sands from shifting further.

“The system is the same. It's just a matter of putting the resources into actually being able to test and measure whether or not those stamp sands are moving into the coastal wetlands moving into the water,” he said.

Bipartisan Infrastructure Law funding

The collaborations for this research with the Keweenaw Bay Indian Community, the University of Missouri, the University of Minnesota-Duluth, and other Forest Service researchers throughout the country was made possible with Bipartisan Infrastructure Law Funding.

“This is exactly what we've been waiting for,” said Zalensy. “We're very grateful to the USDA Forest Service for providing this funding and for allowing us to move this research forward.”

It was funded through the Forest Service which was set aside for research that focuses on cleaning up mining waste, specifically with the use of biochar.

Zalesny says the charcoal-like wood product can do two major things when added to the soil.

“Number one, it incorporates organic matter into the soil. It gives us more agronomic properties or it gives the soil it gives the properties of the soil that the trees actually can thrive in better. Secondly, the biochar will actually adsorb the heavy metals so that heavy metals are attracted to the biochar and it will kind of almost stick to the biochar. That can enhance our phytoremediation,” he said.

The Forest Service is funding four projects across the country using biochar on mining waste.

Zalesny is the co-principal investigator for three of the projects and the lead investigator for the one based in the Upper Peninsula.

The biochar will be added to the soil when the trees are planted. He doesn’t know the exact number of trees he and the team will be planting in the area, but says it will likely be in the 2,000 to 5,000 range.

Beyond mining waste

The research focuses on phytotechnology and which trees are best for removing heavy metal waste from the environment at this specific site.

Zalesny says the ultimate goal is for it to go beyond stamp sands and the U.P.

“The methodologies that we're developing are applicable to other contaminated sites, so not just stamped sands impacted sites. These could be things like areas around landfills, brownfields, which are abandoned industrial areas in urban settings, mine lands, and in addition to agricultural areas that have a lot of runoff from herbicides and fertilizer and those kinds of things,” said Zalesny. “Then any other real harsh sites that might be impacted, let's say on coastal areas with salts and salinity and stuff like that. There's a broad application of this that will help not only provide ecosystem services and also try and read and reduce the environmental impacts, but then also, going back to the human health piece, trying to clean up these areas so that we can mitigate and reduce the potential impacts to humans.”

Zalesny’s phytotechnology research is one of three Rhinelander-based researchers to receive funding through the Bipartisan Infrastructure Law.

Other research being funded includes building climate-resilient forests and forest pest management.

Katie Thoresen is WXPR's News Director/Vice President.
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