Great Northern worked hard to prevent another breach, King said, adding pond capacity and taking other steps. But the plant had two more spills in April, according to a document she provided.
Now the operation has given up on plans to be self-contained and will receive a permit that allows for discharge of clear water, an approach other mines are taking.
One of the biggest operations to run afoul of its zero-discharge plan is Preferred Sands of Blair, Wis. Kevin Lien, director of land management for Trempealeau County, said water from the mine repeatedly overflowed this spring into an intermittent stream that runs into Larkin Valley Creek and on to the Trempealeau River.
“It’s constantly in use and being filled with sediment,” Lien said of the stream.
In a statement to the Star Tribune, Pennsylvania-based Preferred Sands said it has worked closely with the DNR to resolve “complex inherited environmental issues.” The company, which also operates a frac-sand mine in Woodbury, said the Blair facility is not discharging any process water off its site.
Murky wash water
The Midwest’s sand mining boom was triggered by oil and gas companies that use the silica grains in a drilling process called “hydro fracturing” — and they set exacting standards for the sand they buy. To meet those specifications, sand mines in western Wisconsin have had to remove more clay and undersized sand than they projected, several regulators said. The separation process is driving greater water usage and creating larger stockpiles of spent material, Lien and others said.
“This is pretty fussy sand,” said Tom Woletz, Wisconsin DNR’s leading frac-sand expert until he retired last month.
As sand is filtered, the so-called “fines” are washed away from usable frac sand. Mining companies then treat the murky wash water with chemicals, called flocculants, that cause suspended particles to sink so the water can be reused. The clarified water is used to wash more sand, while the wet, sluffy fines are piled as waste material that is eventually plowed back into the ground where sand was excavated.
A well-managed frac-sand site keeps the piles stabilized, sometimes by mixing in top soils, Walls said.
But at the Preferred Sands site in Blair, the waste piles have twice absorbed enough water to turn lava-like and spill from high elevations onto neighboring property, trashing the interior of a house, flowing into a garage on another property and fouling a wetland.
“It’s been a nightmare for us,” said Dick Eberly, a neighbor whose property was tainted by both spills.
Preferred Sands said it will take additional steps in coming months to improve compliance with regulations. “Preferred Sands is fully committed to protecting the environment in the communities in which we operate,” it said in a prepared statement.
Lien said one problem is that some mines have followed a minimum design standard and sized their holding ponds to accommodate the area’s biggest rain event in the past 10 years. In Trempealeau County, Lien and others set a tougher standard, keyed to 100-year rainfall events — but even that hasn’t prevented overflow problems, he said.
“It all looks good on paper when they come in for their permit,” Lien said. “Now we have erosion problem after erosion problem.”
In addition to problems with runoff and waste piles, state officials and some frac-sand companies are wary about the widespread use of a chemical called polyacrylamide to clarify sand-processing water. Polyacrylamide contains residual amounts of acrylamide, a neurotoxin linked to cancer and infertility.
So far, no one has detected acrylamide in aquifers or soil around industrial sand mining sites, and in Wisconsin’s Chippewa County, a rare acrylamide monitoring program in an area with lots of frac-sand activity has not sounded any warnings.