DNR Revisits Stormwater Regulation Following Frac Sand Spill

Stormwater Permit Given To Mine Doesn't Account For Particles As Fine As Frac Sand

Frac sand particles are finer than what the DNR's stormwater permits regulate for. Photo: Public Domain.

Officials with the state Department of Natural Resources said they will begin addressing how the department regulates stormwater after a spill from a frac sand mine in Chippewa County turned a nearby trout stream milky white for days.

After a heavy rain in September, residents near Colfax in Dunn County noticed the stream had changed so that it looked as if someone had loaded it with coffee creamer. The source was eventually traced back to a frac sand mine 12 miles away in Chippewa County.

Industrial sand mines are governed by the same stormwater permits that are written for sand and gravel pit businesses, but DNR enforcement specialist Deb Dix said frac sand mines are much larger and leave more ground exposed.

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“What was happening is that our standard, best management practices that have historically worked perfectly — they no longer worked with the amount of sediment that was moving,” said Dix.

Even though the spill changed the stream for days, it’s possible no rules were broken since the milky white sediment coming from the mine was much finer than what the law requires the DNR to measure for.

“When the testing is done they use a specific filter, which will catch a grain size,” said Dix. “With the required test methods that we have in code, these smaller grains will go through the filter.”

The DNR is currently re-writing its stormwater permit to address new challenges brought by frac sand mining. The agency says a public draft should be available later this fall.