Scientific Team Creates Underground Map to Address Rhinelander PFAS Problems
Last week, ground-penetrating radar sensors glided across the grass near Rhinelander wells 7 and 8, attached to a customized four-wheeled cart.
UW-Madison researcher Dante Fratta pushed the cart and looked at a set of squiggles on a screen.
“What you’re seeing here is a ground-penetrating radar system,” Fratta explained. “It uses the same techniques as a radar at the airport would use. Instead of sending electromagnetic waves into the air, it sends electromagnetic waves into the ground.”
Fratta and his colleagues were using this tool, along with seismic probes and electrical resistivity, to see the underground layers of rock, groundwater, and soil near the wells.
UW-Madison geological engineer Jim Tinjum leads the project.
“What we’re trying to do is get that picture of what the hydrogeologic and geological situation is within the catchment zone around Rhinelander Wells 7 and 8,” Tinjum said. “In layman’s terms, [we’re getting] a 3D map of the subsurface.”
Tinjum and his team already know some things about the water below the ground.
“We call it an unconfined shallow aquifer, which means that it’s very prone to contamination from surficial surfaces. There’s nothing protecting it at the surface,” he said. “This is all shallow. It rains. It goes into the aquifer. It hits your wells fairly quickly.”
Creating an underground map in this area is especially important.
Municipal wells 7 and 8, located at the Rhinelander-Oneida County Airport, have been shut down for two years. Testing showed water with elevated levels of PFAS chemicals was being drawn from the wells into the city’s water system. PFAS has links to health concerns, including cancer, when ingested.
Tinjum’s team is seeking to find out whether the explanation for the contamination is one of those things or something else altogether.
Just outside the building housing Well 7, Chris Zahasky prepared a cylindrical metal auger.
“This auger is essentially just a smaller version of what you use when you’re drilling through the ice in the wintertime,” he said. “We use that to go and pull up these soil and sediment samples.”
The characteristics of the soil will be used with the underground map to get an even better picture of what’s going on under the surface.
“We want to go and use these samples to get measurements to understand how the PFAS goes from some sort of surface source, depending on what that source might be, down to the groundwater aquifer,” Zahasky said.
The PFAS situation in Rhinelander is certainly not ideal.
But Mayor Chris Frederickson sees it as an opportunity to invite in pioneering researchers and companies to tackle a problem that’s expanding nationwide.
“We have an opportunity here to take our problem and give it to people, as far as research, as far as engineers, as far as competitive nature of capitalism…using that competitive nature as a petri dish and saying, come fix it,” Frederickson said. “Whatever comes out of it, you get the profit of that. We just get it fixed. That’s what we want.”
Frederickson’s best-case scenario is seeing researchers and companies create PFAS response technologies in Rhinelander that can be replicated elsewhere.
“We may have led the state or somewhere else in this chemical being around. But we also can lead, then, in fixing it,” he said.
The underground mapping work near the wells is just step one of Tinjum’s plan.
The maps will help inform step two.
“[They will] provide us data to more accurately and be more specific on future investigations where we may put in wells to collect water for PFAS analysis,” Tinjum said.
If step two investigations can identify PFAS plumes in the aquifer, step three is figuring out the best way to address or treat them.
Tinjum’s team is interested in what it can learn from its water research. But the greatest goal is to make the water safe for the people who drink it.
“Ultimately, we want to make the best decision to protect the citizens of Rhinelander and do that in the best value proposition that we can,” he said.
The work of the UW-Madison team is supported by a $40,000 grant from the Wisconsin Alumni Research Foundation.