Frac Sand Deposits Are Abundant In Wisconsin
Although sand has been mined across Wisconsin for over a century, the large-scale mines and associated processing and transportation facilities are relatively new.
Much of the sand mined in Wisconsin in recent years is shipped to places like North Dakota, Texas, Oklahoma and several Appalachian states to be used in hydraulic fracturing, a method of extracting petroleum and natural gas from rock formations, usually deep beneath the ground's surface.
Over the early 2010s, Wisconsin saw a dramatic increase in the number of new frac sand mine and processing plant proposals. This rapid expansion was more than state and local officials were used to handling, Wisconsin Geological and Natural History Survey geologist Jay Zambito said in a Jan. 28, 2015, talk recorded for Wisconsin Public Television's University Place.
Wisconsin has voluminous sand deposits that meet specifications for use in hydraulic fracturing, which is widely known as fracking. These deposits are found among sandstone formations that are located primarily across western and central Wisconsin. Mines are sited in clusters where sands can be easily extracted at less than 100 feet beneath the ground's surface. In fact, Wisconsin has more of this sand than anywhere else in the United States, Zambito noted.
The frac sand boom in the state has raised controversies about the mining operations, over issues related to local nuisances and environmental impacts. For example, frac sand mines have raised concerns about nearby surface and groundwater levels, Zambito noted. Some counties allow companies to mine sand below the water table, which can have a greater effect on surface and groundwater than mining above it, which is more common in Wisconsin. Sand mining operations use well water to transport, wash and sort sand onsite. Although many mines recycle this water, they also pump more to replace supplies lost to evaporation and infiltration.
Zambito said a study the Wisconsin Geological and Natural History Survey has been conducting with the U.S. Geological Survey in Chippewa County examines groundwater to learn how pumping of high-capacity wells affects streams and other nearby wells. It also is studying changes in pumping rates, well placement and their effects, and how to use such information for decision-making.
Other concerns Zambito noted include future land use, economic pacts, noise from blasting or truck traffic, trucks' impact on roads, and effects on air quality from dust leaving the mine site. He also discussed the history of sand mining in Wisconsin, different rock formations around the state and their geological history, how frac sand is mined and its use in hydrofracking.
The fortunes of frac sand mining are linked with the global market for fossil fuels, which fluctuates amid international politics, growing renewable energy sources, and efficiency gains spurred by concerns about costs and climate change. It all makes for a boom-and-bust cycle. Demand for frac sand declined in 2015 and 2016 as oil prices dropped, but it's expected to increase in 2017, with a couple Wisconsin mines reopening in anticipation of new business opportunities.
- The Wisconsin Geological and Natural History Survey has drill cores from more than 2,000 holes throughout the state, cuttings (materials recovered when boring a hole as opposed to coring one) and 50,000 hand samples from hundreds of studies throughout the state, going back over a century. Most of this material is irreplaceable.
- People have conducted non-metallic mining in every county across Wisconsin for more than 100 years. Non-metallic mining products include sand, gravel, crushed stone aggregate (such as limestone for roadbeds), flagstone and clay. Sand for hydraulic fracturing is one kind of industrial sand mined in the state. Industrial sand also is mined for foundry molds, glassmaking, water filtration or filter packs at the bottom of wells, abrasives for sandblasting and golf course sand traps.
- Hydraulic fracturing is a technology used to extract oil and natural gas directly from source rock. The more conventional method involves drilling into a reservoir of fossil fuel that migrated from source rock through porous rock and became trapped. Hydraulic fracturing is combined with horizontal drilling along the source rock. Once the horizontal well is drilled, water and sand are injected at high pressure to fracture the rock. The sand flows into those fractures and remains in place, increasing the porosity and permeability of the source rock to allow hydrocarbons trapped in small spaces to migrate to the surface.
- Wisconsin is known for its quartz sand. Its size and round, spherical shape is ideal for hydraulic fracturing. (A grain of sand can be highly spherical but still angular, but another grain can be well-rounded but not spherical.)
- Industrial sand mines remove 20 million to 95 million gallons of groundwater per year per well, most of which is recycled on site and reused, infiltrates back into the ground during the sand-drying process, or deposited in settling ponds. (In contrast, municipal water systems extract 80 million to 90 million gallons per year per well, most of which is transported the pumping site to be treated. Meanwhile, agricultural irrigation systems draw 10 million to 30 million gallons per year per well, much of which is lost to plant growth or evapotranspiration.)
- Frac sand mining is influenced by global fossil fuel demand, the location of the local water table, regional transportation infrastructure, and the political and regulatory climate.
- Hydraulic fracturing is not conducted in Wisconsin, which does not have any identified oil or gas deposits that are economically feasible to extract.
- On the origins of Wisconsin's sand: "Wisconsin has not had a complex geologic history in the last 500 million years. And so a lot of that [sand] material has not been eroded away. In fact, Wisconsin has more of these shoreline deposits that are near the surface than any place else in North America."
- On frac sand mine variability: "Every mine is different, every mine is site specific. They all have slightly different geology. They all have slightly different reclamation plans that they've worked out."
- On groundwater management: "Groundwater is like a cup, and everybody's putting their straw in, and so we need to think about who's putting in their straw, how many straws is everybody putting in, and how often are they taking a sip because it's a shared resource and we obviously want this to be something that can be used sustainably."
- On the role of Wisconsin-sourced sand in the economy: "While sand mining is going on in Wisconsin, that sand is being transported across the United States. Wisconsin is also playing a role in U.S. energy independence and the nation's economic recovery."