Three years ago, water samples from ponds at Wisconsin frac sand mines showed concentrations of heavy metals many times higher than state groundwater standards recommend. Now, the state’s Department of Natural Resources (DNR) is planning a study to see if the metal from those ponds is leaching from mines and polluting groundwater, according to Rich Kremer, writing for Wisconsin Public Radio.
But two similar studies are already underway aimed at better understanding what’s in the region's water and the sand that's mined there. Areas like a section of land outside the city of Arcadia, Wis., where the Tunnel City and Wonewoc sandstone formations meet are especially rich in minerals containing heavy metals, according to Wisconsin Geological and Historical Survey geologist Jay Zambito. The minerals are what keep metals locked inside the rock formations, Zambito said. His theory is that when miners break the rock up, the minerals might dissolve.
They found aluminum concentrations 178 times higher than state standards along with lead and manganese levels four times what the agency recommends for groundwater. But the water was cloudy with sediment and researchers couldn't tell if those metals were in the sediment or the water itself.
DNR frac sand specialist Roberta Walls said that's why they're moving forward with a comprehensive groundwater study next year, which could be finished in time for a review of sand mining water pollution permits. The next DNR review of industrial sand mining water permits is scheduled for 2021.