Innovative Iron Range landfill project tackles climate change, ‘forever chemicals’
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Landfills aren’t typically associated with green innovation. But a new project at a small landfill on the Iron Range is simultaneously helping to tackle two of society’s most vexing environmental problems — climate change and the treatment of so-called “forever chemicals" such as PFAS.
The effort uses geothermal energy by capturing the heat released by decomposing garbage. It will then be used to help power a new wastewater plant to treat PFAS and other pollutants in the water that leaches out of the landfill.
It’s the first project of its kind in the state and one of only a handful across the country. And it’s one that St. Louis County officials believe will be replicated across the state as efforts to scrub PFAS out of the environment intensify.
“Because everyone has to start managing their wastewater and doing it correctly,” said St. Louis County Commissioner Keith Nelson during a ribbon cutting ceremony at the landfill earlier this month. “What we’re doing here is state of the art.”
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Free heat
Every day at the St. Louis County Regional landfill outside Virginia, more than 450 tons of waste gets trucked in from across a swath of northeastern Minnesota — an area larger than the states of Rhode Island and Connecticut combined.
There, it’s heaped onto a small mountain of trash some 80 feet above the ground, on top of waste rock from an old iron ore mine. Bald and golden eagles circle overhead with seagulls and other birds, searching for their next meal.
An 80,000 pound landfill compactor with studded steel wheels drives back and forth on top of the garbage, squeezing nearly a ton of trash down into a single cubic yard.
All that trash creates a lot of heat as it decomposes. At all but a handful of landfills across the country, that heat escapes and is wasted.
But here, under a new 10-acre cell of the landfill, the county has installed 8 miles of tubing filled with a liquid similar to what’s inside a car radiator. That liquid will transfer the heat to a new on-site wastewater treatment plant the county plans to break ground on next summer.
“It really is a simple concept, and I couldn’t believe that it hadn’t been done in Minnesota or somewhere up north where you were capturing that free source of energy and free source of heat,” said Dave Fink, St. Louis County director of environmental services.
An engineer at the global environmental services company Stantec suggested the technology after working on a similar project in New Hampshire.
A typical geothermal system pulls heat out of the ground at around 40 degrees in the winter. When garbage decomposes in a landfill, it creates temperatures up to 120 degrees.
“I think every landfill should do it,” said Brett Ballavance, senior environmental engineer at Stantec. “It was eye-opening. And for the cost, it’s a worthy investment."
This phase of the project cost about $3 million. The geothermal technology cost only $30,000, about 1 percent of the cost.
Cleaning ‘forever’ chemicals
St. Louis County plans to break ground on a new $15 million-$17 million wastewater treatment plant at the landfill next summer. The geothermal energy will be used to heat the 10,000-square-foot building and heat the wastewater to aid in treatment.
It will be the first plant built directly on-site at a landfill in Minnesota with the ability to treat water for PFAS, or per- and polyfluoroalkyl substances.
They’re called “forever chemicals” because they don’t easily break down in the environment on their own. And they’re found in a huge range of products, everything from nonstick cookware to carpet, clothing to cosmetics. They’ve been linked to several negative health effects, including kidney and thyroid problems and cancer.
When products containing PFAS are dumped at landfills, the chemicals — along with other pollutants — accumulate in the water that leaches through the waste.
“Water comes out of the sky, hits the landfill, much like water hitting your coffee grounds, filters through all of that, where it picks up all of the metals and nitrates and ammonias and cobalt and everything that leeches out of the waste mass,” said Steve Pellinen, St. Louis County environmental services planner.
The Minnesota Pollution Control Agency (MPCA) has found high levels of PFAS in groundwater at landfills across the state.
In a recent study, the agency found PFAS in groundwater at amounts higher than the state’s acceptable levels for safe drinking water at nearly 60 closed landfills.
At modern landfills, liner systems beneath the waste capture the water — called leachate — before it soaks into groundwater.
At the St. Louis County landfill, it will be piped to the new treatment plant starting at the end of 2026 where it will be treated with a technology called reverse osmosis.
The PFAS and other pollutants left over will be placed back into the landfill, creating a closed-loop system.
The alternative would be to truck the leachate to a large wastewater treatment plant in Duluth managed by the Western Lake Superior Sanitary District.
But it would be prohibitively expensive to truck five to six million gallons of landfill leachate more than 60 miles each way every year, said Pellinen. Additionally, there are no municipal wastewater treatment plants in the state, including the plant in Duluth, that are equipped to treat PFAS.
“We don’t want to take anything to them, because we’re worried about Lake Superior and the potential impacts of this stuff in the lake,” Pellinen said.
St. Louis County officials say they are getting inquiries from around the state and country about their project.
A big potential obstacle is cost. A recent MPCA analysis found it costs anywhere from $400,000 to $12 million over 20 years to remove just one pound of PFAS from landfill leachate.
“That’s a lot of money,” said MPCA environmental engineer Scott Kyser. “You can remove conventional wastewater pollutants for hundreds of dollars per pound. So we’re talking orders of magnitude more to remove PFAS from water.”
Kyser and other state officials praise the St. Louis County project, calling it “ahead of the curve.” They plan to monitor the effectiveness of the PFAS treatment, as well as the costs involved.
“Because that’s really a barrier for facilities around the state and around the country,” said MPCA spokesperson Adam Scott.
That’s why state officials are focusing on pollution prevention. It’s much cheaper to prevent PFAS from escaping into the environment in the first place than it is to clean it up once it’s there.
Starting next year, Minnesota’s new PFAS pollution prevention law, known as Amara’s Law, begins to take effect. It requires 11 categories of consumer products be made without PFAS in order to be sold in the state.
By 2032, all other nonessential use of PFAS in products will be prohibited.
In the meantime, St. Louis County officials say they plan to do their part to protect the region’s water resources.
As the county closes sections of the landfill, they’re exploring covering the top with solar panels to help offset the electricity costs of running the new wastewater treatment plant.
“We have the cleanest water in the state of Minnesota,” said Nelson. “We want to keep it that way now and into the future.”