Respirable Crystalline Silica from Sand Mining

Sand Mining in Wisconsin

Sand mining is not a new practice in Wisconsin. The recent demand for high-quality quartz sand for a natural gas drilling process called hydraulic fracturing (also known as “fracking” or “fracing”), however, has greatly increased this activity – especially in Western Wisconsin. While Wisconsin has deposits of sand that are used for the hydraulic fracturing process, the drilling occurs in shale deposits containing oil and natural gas that are found in other states, such as Texas, North Dakota and Pennsylvania. Sand mining operations designed to mine and export ‘frac sand’ are often much larger in acreage than the smaller, more traditional Wisconsin sand mines that serve mainly local needs for sand. The sand is desirable for fracing and some other uses due to its size, shape, and crystalline silica properties and because the deposits are usually close to the surface and easy to mine. An increase in the number of new requests for mining and processing plant permits has led several communities to raise questions about the possibility for respirable crystalline silica (RCS) to be generated at mine sites, and how RCS might impact the health of nearby residents.

What is respirable crystalline silica (RCS)?

Dust can be made up of visible (larger) and microscopic (smaller) particles. Particulate matter is defined as airborne material (solid or liquid) that is smaller than 100 microns (millionths of a meter) in size. For comparison, human hair is typically between 70 to 100 microns in diameter. The size of the particulate matter affects how long the particles can stay airborne and how far particles can travel before settling out onto surfaces. Smaller particles stay airborne longer and thus can travel further than larger particles.

Respirable crystalline silica (RCS) refers to particles of crystalline silica less than four microns in size, or particulate matter 4 (PM4). PM4-sized particles can penetrate deep into the lungs, where the most critical effects of RCS– silicosis and cancer – are thought to occur.

What concerns are being raised by communities near newer sand mining operations?

In addition to silica dust and RCS, the transportation of sand may raise other concerns among residents of communities near sand mining operations. New mines are likely to increase truck and rail traffic, and may increase diesel emissions, noise, road congestion and accidents, and road maintenance needs. Water resources and reclamation of the site can also be areas of public interest. Effective communication and cooperative planning between mining companies and local communities is essential.

What can communities do to protect residents’ health?

By incorporating best practices into the mine’s daily operations on and off-site, mine operators and communities can work together to create a mining operation that is economically viable and protective of the health of workers and the surrounding community. Local agencies have an opportunity to influence sand mining operations primarily through zoning and direct negotiation with mine developers to use best management practices appropriate for the specific location.

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Last Revised: April 22, 2020