The rise of fracking as a method for extracting natural gas from shale rock has triggered demand for a key ingredient in the process: silica sand. In parts of the upper Midwest, there's been a rush to mine this increasingly valuable product.
In northeast Iowa, a mine recently reopened to profit from the new demand. It's owned by the Pattison family, who have run a grain business for decades. They had been storing the grain in the old, unused mine tunnels carved into the cliffs and then loading it onto barges to ship downriver. They pretty much ignored the sandstone all around them.
But then one day owner Kyle Pattison got a phone call.
"We decided to open the mine because of being requested by a fracking company to," Pattison says. "They asked us to supply sand, for frack."
So with a nudge from the natural gas industry, Pattison sold his grain business and opened up Pattison Sand Co.
And he's not the only one to jump into the business. Sandstone deposits are plentiful and accessible across the upper Midwest and in Texas and Oklahoma. Dozens of companies are ramping up production and expanding their mines and quarries to meet the huge demand. But why can't the natural gas industry get enough of this sand?
"This sand happens to have lot of properties that they covet. So they're descending on all these areas to provide their sand for their shale gas fracking operations," says Iowa State University geologist Bill Simpkins.
He says the industry is using silica sand because of its unique spherical shape and incredible toughness. To extract natural gas bound up in shale rock, energy companies drill thousands of feet down and then blast pressurized water and chemicals into the shale to fracture it.
"And the role of t he sand is to keep the fractures open," Simpkins says.
Other materials can do the same job, but sand is the cheapest. According to U.S. Geological Survey data, production of frack sand has more than quadrupled since 2000.
Tom Dolley of the U.S. Geological Survey says he's not sure just how many frack sand mines there are across the country, but he says the industry is growing. "It's happening so quickly it makes my head spin sometimes," Dolley says.
One region that's seen huge growth is in Wisconsin, which is already the nation's second-largest industrial sand mining state after Illinois. Wisconsin Department of Natural Resources official Tom Portle likened the surge to the gold rush.
"There's been other counties where there's been frack sand mines for many, many years, and they've just kind of been sleepy deals, kind of under the radar, steady business, but not explosive like we're seeing now," Portle says.
Back at the Pattison Sand Co. in Iowa, business has been booming. Over the past 6 months, the company has hired 50 workers.
To enter the mine, you have to drive a diesel truck — because gasoline is too combustible — down a switchback road that winds its way to the bottom of the 300-foot bluff to an opening carved into the cliff's side.
After decades of using the mines just to store grain, sand is flying out the door. Pattison ships as many as 45 rail cars full of sand each day. A back-of-the-envelope calculation shows that could bring in more than $100,000 a day.
Dolley says this sand fetches a much higher price when used for fracking than for construction or even making glass bottles.
"There's considerable variation in price, but yeah, frack is gonna be over double what you would see for glass container price," he says.
In Iowa alone, the Pattison mine could easily have enough sandstone to last 10 years. That's a lot considering that to meet fracking demand, it's running 24 hours a day, 7 days a week, all year long.
Kathleen Masterson reports from Iowa for Harvest Public Media, an agriculture-reporting project involving six NPR member stations in the Midwest. For more stories about farm and food, check out harvestpublicmedia.org.