“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.’
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.”…