LaSalle County Plays Important Role In Fracking

Dec 23, 2014


You know it's controversial, but why that's the case may not be something that you can explain easily at a dinner party.

Besides, this is the Midwest. Isn't it a bigger deal out West?

Credit Illinois DNR

Not exactly.  Illinois regulators and activists have been agonizing over state fracking rules because there's money to made underneath the ground in southern parts of the state ... and there are environmental concerns.

But northern Illinois shouldn't be left out of the equation. LaSalle County, home of Starved Rock State Park, sits atop an ancient beach where sand was prevalent. And it's good sand: perfectly rounded quartz gems. Sand like that is used to get oil and natural gas to the surface. That sand now lies beneath precious farmland. And people live on and near this land.

Starting to see the conflict?

U.S. Geological Survey: Silica Sand

Mike Phillips is a geologist who teaches at Illinois Valley Community College in Oglesby.


PHILLIPS: Several hundred million years ago, there was a beach here in northern Illinois. It was a beautiful, white sand beach just like if you went to your favorite beach on the Gulf Coast or on the east coast. So picture a beautiful, white sand beach. At the time, there was no land vegetation or anything so this sand deposited here is this beautiful, clean white sand that is 95-99% pure quartz. So a lot of sand beaches might have a little bit of extra, other kinds of sand mixed in. This is an especially clean sand that's made almost exclusively of quartz, which is silicon dioxide, so that's why people call it silica sand.

How common is it across the U.S. or, particularly, in the Midwest?

PHILLIPS: Well, this deposit -- the silica sand deposit -- has a name. We call it the St. Peter sandstone because it sticks out of the ground near St. Peter in Minnesota.  The St. Peter sandstone is present in Minnesota, it's underneath Missouri, Iowa, Illinois, [and] Wisconsin, so it covers a very large area in the Midwest. But in most places it is really deep -- too deep to mine. There's kind of a large fold in the rocks underneath LaSalle County, and that fold, kind of at the peak of that fold, brings the layer of silica sand right up to the surface. So, that makes it very convenient for mining because you just have to remove a little bit of rock and dirt from on top and then you have direct access to that sand.

Can you speak to how this sand is used in fracking?

PHILLIPS: The thing about a beach sand is that the waves wash the sand over and over. It's like a natural tumbler. So, our silica sand has been through this process, it was hundreds of millions of years ago that this happened. It essentially got tumbled over and over and so all the sand grains are really pretty round.

And, quartz sand is a very durable kind of mineral so it doesn't dissolve in water, and it's pretty hard and strong. What they use it for, when they drill down into the ground for fracking, the rocks that they drill into have oil or natural gas in them, but the rocks are made usually of clay. The clay or shale that they drill into is very hard, and the liquid or the gas does not move through there very easily.

If you push water under very high pressure into those rocks, they fracture, so that's where the name "fracking" comes from. They fracture those rocks. Once you create fractures, you have the opportunity for the oil or natural gas to move out of the rock into the fractures and into your well.

But as soon as you pull fluid out, then the fractures close, and then nothing comes. So you need something to prop open those fractures. What the silica sand is used for is, they pump the water down the well, and they put in some silica sand, and when they pull the water out, the fractures can't close up because the sand is there to hold the fractures open. Then, the natural gas or oil can come into the well through those fractures that are being propped open with silica sand.

Does Illinois have enough silica sand, or does LaSalle County have enough silica sand, to be used for how much energy potential is in southern Illinois?

PHILLIPS: Oh yeah. I mean we have lots and lots of silica sand. With any natural resource, with any geologic resource, the amount available for production is partly dependent on what people are willing to pay for it. So, we have some sand, a lot of sand, that is relatively inexpensive that is close to the surface.

If demand went up, and the price went up, then the mining companies would probably be willing to dig a little bit deeper to get the sand. So, we have lots and lots of sand. I mean the supply is limited and it is also limited by how much of the landscape we are willing to exchange for taking out the sand, because when you dig a giant hole in the ground to get out the sand, then when you are done mining, that big hole in the ground isn't really useful for anything else.

One of the concerns people have is if we keep that land as farmland, if it's good farmland, you can grow crops on that farmland year after year after year. If you decide to scrape off the topsoil and dig out the sand, even when you are done mining, you have a big hole in the ground that's probably not going to be useful for farming anymore. Digging out the sand is kind of a one shot deal and then you are done. If you compare it to farming, farming you can keep doing forever as long as you take care of the soil.

Anything else you would like to add about silica sand and its use in fracking that we didn't get to touch on?

PHILLIPS: Well, I think one of the things that's mentioned is that fracking has been something that has been done for close to 100 years, which is correct. But one of the big changes that's happened in the last 20-30 years is we developed new technology that allows us to drill horizontally.

Most people, when they think of a well, think of a hole that goes vertically straight down into the ground. In oil fields in the past, what they would do is they would fracture around that vertical well and it wouldn't take very much sand. Right now, they are able to go horizontally, I believe up to two miles. So, if you have a horizontal well that is two miles long and you fracture that, that uses a lot more sand. One of the important things to remember is that it's a technology that we've had for a long time, but we have found a new way to use it that requires us to use a lot more sand. 

The other thing that people have to keep in mind is that it is very attractive to use this to get a little bit more gas or little more oil out of the ground, but there are limits and trade-offs with all of these technologies, and with all of these methods of doing business. A really good example is, if you dig this really big hole in the ground, you are trading some sand today for the ability to farm tomorrow.

And, of course, for the people who live nearby one of these facilities, they are very concerned about how the facility operates. So, if we look at some sand mines, the operators are very careful to make sure that the sand that they mine doesn't produce dust that blows off the property. Other property owners and mine operators maybe aren't as careful as they should be, and they have a bigger impact on their neighbors.  

Some sand mines go into places where the farmland isn't very good, and so their impact on our ability to farm in the future is not as much as somebody who puts their mine underneath what we would call "prime" farmland. So, there are a lot of concerns that neighbors and local people have in terms of the long-term prospects and also in terms of how the mine is operated.

The people who own the property that want to mine it have a right to mine it, but the neighbors also have a right to maintain their lifestyle. So, one of the jobs of the state and the local government is to balance the needs of those people. And, it's not easy, it's not easy to do.