Only 20 percent of active frac sand mining operations have been inspected by the Department of Natural Resources to ensure that they’re complying with state air pollution permits.

A frac sand company must get an air permit from the DNR before building a mine, processing center or rail-loading facility. Once operating, it’s up to the agency to do a full compliance evaluation to prove the company is following the rules. However, the number of frac sand operations in the state grew more than tenfold between 2010 and 2013 and the DNR wasn’t able to do any full compliance checks on most operations during those years.

In their last budget, the agency asked for two additional staff for monitoring air permits, which it got. Environmental Engineer Supervisor Jeff Johnson said that with the added help they planned on doing full inspections on all frac sand operations this year. However, at the end of September, they’re still behind.

“We’re finding with the number of sources that we’ve got … we may end up only doing half the number of sources out there per year,” said Johnson.

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Since July of last year, 29 out of around 135 active sand operations have had full inspections.

Gov. Scott Walker says if the DNR is still having trouble keeping up, he’ll consider adding more staff.

“We’ll be looking in this next budget process probably to put some more,” said Walker. “We’ll talk with the DNR in terms of how many more, but that’s part of what brought the two on from the last go-around.”

The DNR said it’s been able to do more partial compliance checks on frac sand operations. In those cases, staff drive around the site and look for obvious violations.