Wisconsin’s sandstones, especially the Cambrian- and Ordovician-age formations, are prized for their uniform grain size and high silica content. These formations are excellent sources of the raw material needed for many industrial products and processes, including hydraulic fracturing (fracking) for petroleum recovery.
Frac sand primer
Wisconsin has abundant resources of sand that have been mined for more than 100 years. Our sand is used for glass manufacture, foundry molds, even golf course traps. It has been mined for the petroleum industry for many years. Recent advances in extracting oil and gas using a process called “fracking” (short for hydraulic fracturing) have greatly increased the demand for Wisconsin’s sand.
What is frac sand?
Frac sand is quartz sand of a specific grain size and shape that is suspended in fluid and injected into oil and gas wells under very high pressure. The fluid pressure opens and enlarges fractures as well as creates new ones. Sand grains are carried into these fractures and prop them open after the fluid is pumped out.
The type of sand used in this process must be nearly pure quartz, very well rounded, extremely hard, and of uniform size. Before shipment, frac sand is washed, sorted to ensure uniformity, and dried.
Wisconsin has some of the best frac sand in the country because several of our geologic formations meet these specifications and are found near the surface.
Where is frac sand found?
Frac sand is currently being mined from sandstone formations in much of western and central Wisconsin. The same formations are less well exposed and generally more fine-grained in the eastern and southern parts of the state. Sand from younger glacial deposits as well as most beach and riverbank sand is too impure and too angular to be used as frac sand.
Where is fracking performed?
Fracking has been used by our domestic oil and gas industry for the past 75 years. Recently, the development of new horizontal drilling technology using hydraulic fracturing has made possible production of previously unrecoverable natural gas resources in the eastern, western, and southwestern United States.
In Wisconsin, a different kind of fracking is used to increase the productivity of water supply wells in relatively impermeable rocks, such as the granite in the central part of the state. In these cases, only pressurized water is injected into the well—no sand is added.
Permits and regulations
Concerns have been raised regarding environmental and nuisance problems as sand mines proliferate. Mine siting is regulated at the local zoning level. Mine reclamation plans, required by NR 135, must be in place before mining begins. The Department of Natural Resources provides technical assistance to local authorities for these plans. For a summary of Wisconsin’s nonmetallic mining regulations, visit the DNR website.
For more information
Contact the following staff at the Wisconsin Geological and Natural History Survey for more details about frac sand in Wisconsin:
Mine locations map: Wisconsin Department of Natural Resources—Industrial Sand Mining
Interactive map shows locations and types of frac sand mining operations
- Wisconsin Center for Investigative Journalism: Covers a variety of topics about frac sand mining
- Wisconsin Department of Natural Resources—Silica Sand Mining Report: Overview of the industry and potential impacts (PDF)
- U.S. Geological Survey: Frac Sand in the United States—A Geological and Industry Overview: Description of frac sand deposits and locations, and estimates of production, consumption, and reserves. A companion map shows locations of frac sand sources across the United States.
Economics: The Federal Reserve Bank of Minneapolis—Regional Business & Economics Newspaper
Article outlines the economic evaluation of frac sand mining (PDF)
Mining statistics: U.S. Geological Survey—Silica Statistics
Annual reports for national silica mining statistics
Planning and zoning: Center for Land Use Education (UW–Stevens Point)—Mining Publications and Resources
Four-part series on planning, zoning, and evaluating county nonmetallic mining plans
- Wisconsin Department of Natural Resources—Industrial Sand Mining: Information on WDNR regulations, air monitoring, silica sand, and rules governing reclamation
- Wisconsin Legislative Council—Information Memorandum: 10-page report detailing types of ordinances that a local government may enact to regulate sand mining plus examples of state and federal permits that might be required for certain environmental impacts (PDF)
Silica dust: Occupational Safety and Health Administration—Crystalline Silica
Occupational health hazards and symptoms of exposure to silica dust