Frac sand mining has raised concerns about environmental health impacts on surface and groundwater resources. Several spills have occurred in which waste water or sediment escaped from holding ponds used by frac sand mines. In May of 2012, for example, at a mine in Burnett County owned by Minnesota-based Interstate Energy Partners, sand and other sediment leaked for several days from the damaged holding pond into the St. Croix River until it was discovered by a hiker. Also in May of 2012, a mudslide at a Preferred Sands mine in Trempealeau County flooded a neighbor's property during a heavy storm. Both incidents have been referred to the Wisconsin Department of Justice by the DNR. In June of 2013, four frac sand mines in Trempealeau County and two in Barron County were unable to handle heavy rains, causing sediment to leak into nearby streams, rivers and wetlands.

Separate from such incidents, concerns have been raised about water usage and quantity. Many frac sand operations have high-capacity wells and use millions of gallons of water a month to process sand or as part of fugitive dust control measures. Some processing plants use 4,000 to 6,500 gallons per minute to move and wash raw material. The Wisconsin Geological and Natural History Survey is currently spearheading a five-year study in Chippewa County to evaluate how frac sand mining and other activities impact groundwater recharge and withdrawal.

One of the main concerns commonly raised by citizens revolves around the use of chemicals in the washing and processing of frac sand. Given the large quantities of water used to move and wash sand, processing plants seek to reuse water wherever possible. Chemicals known as flocculants, widely utilized in waste water treatment plants, are introduced during processing to cause sediment in murky water to clump together, allowing water to be separated from unwanted material and then reused. Some flocculants contain potentially toxic chemicals, known as acrylamides and polyacrylamides, and experts lack a clear understanding of what happens when these chemicals are buried with mine waste or seep from holding ponds into groundwater systems.

In 2016 the Wisconsin DNR announced that they plan to study whether heavy metals leach from holding ponds into groundwater. Water from these ponds have been found to contain elevated levels of aluminum, copper, arsenic, and lead, likely released from the clays during processing of frac sand.

News Reports 

Groundwater Study in Chippewa County (2011-16)

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