Almost all human activities result in some form of air emission. To protect human health and the environment, the United States Environmental Protection Agency (USEPA) and Illinois Environmental Protection Agency (IEPA) have issued scientifically-based air quality regulations. These regulations and regulatory programs establish safe levels of emissions associated with activities from a broad range of air emission sources such as vehicles, electric power generation, the manufacturing industry and the mining industry. These regulatory programs require a permit to control regulated emissions to below safe levels, to track emissions, and to report to the IEPA. Like other industries, mining companies work hard to maintain compliance with their specific air permits. Regulatory agencies monitor the mining industry for compliance with air permits, and also conduct ambient air monitoring around the state.
Air operating permits
Mining in La Salle County is regulated by the Illinois Environmental Protection Agency (IEPA). The IEPA Bureau of Air is in charge of enforcing Federal and State air pollution regulations. Mine operators are required to obtain a construction and/or operating permit from the Bureau of Air for the regulation of pollutants generated by the operation.
Mine operators are also required to file an Annual Emission Report to the IEPA each year outlining their emissions based on recorded production levels and emission rate factors generated by USEPA research data. Operators are also required to submit reports to the IEPA when site operations deviate from the conditions contained in the construction or operating permit for the site. When new equipment is introduced into the production process, operators are required to notify the IEPA and may be required to test the equipment to ensure compliance with limits and submit the test results within a specified period of time.
Most emissions associated with mining and mineral processing activities are known as particulate matter (PM) or dust. Other emissions from this industry can include combustion exhaust because some mines use fuels to dry or otherwise process the mineral. Combustion exhaust can also be associated with equipment that use fuels to pump water or generate power.
Particulate matter or dust emissions
Dust may be generated by activities on a mine site that are potentially visible to passing motorists and neighbors. Mine operators use “best management practices” to control dust such as observing posted speed limits and ensuring trucks are not overloaded, thus reducing spilled product. Paved entrances, on-site water trucks, street sweepers, wheel wash systems, vegetation, and so on may be employed as dust controls.
Construction sand, gravel, stone (aggregates) and industrial sand (silica sand) extracted in La Salle County have a normal natural moisture content between 2% and 4% which, according to USEPA research data, provides adequate pollution control to convey raw materials onsite.1 Dust emissions from processing operations are easily controlled and the dust typically does not travel beyond the plant area. In addition, most construction aggregates and industrial sand mined in La Salle County are washed at the plant to remove silts and clay before sizing to meet customer demands and therefore, produce minimal dust at the plant because the materials become saturated during processing.
1. (USEPA, AP 42, Fifth Edition, Volume I, Chapter 11: Mineral Products Industry, 11.19.1 Sand And Gravel Processing; Accessed 10/17/2014)
Crystalline silica emissions
Crystalline silica, in the form of quartz, is the second most common material in the earth’s crust, making up 12% of the earth’s surface. Quartz particles are released by erosion of rocks and transported by water. These angular particles are rounded during transport, and the rounded particles become a quartz sand deposit, like the Lake Michigan shoreline. In LaSalle County the quartz was deposited along the shoreline of an ancient sea. Because silica is so common, it is found everywhere - in dirt, sand, gravel and rocks. It is a common part of most building products and it is in the air at low levels nearly everywhere. Sand-sized crystalline silica is not a health concern because the particles are too big to enter your lungs. The crystalline silica of interest for health is when it is present in dust. Dust can become airborne in this county by disturbing the soil, such as farmers tilling the soil, harvesting, and mining. Air permits have conditions to reduce the potential for dust to become airborne at mines.
There is no evidence that the low levels of crystalline silica found in the ambient air in the United States or around industrial sand mines cause illness or disease.2
Most silica sand in La Salle County is hydraulically mined. Under high pressure, water is sprayed into the disaggregated sandstone, creating a sand-water slurry. The slurry is pumped to the processing plant where it is washed again to remove silts and clays. Water used in mining and processing helps to reduce airborne crystalline silica emissions.
2. (Wisconsin Industrial Sand Association. Crystalline Silica May 2013. http://www.wisconsinsand.org/assets/Crystalline-Silica-Final-May-2013.pdf. Accessed 10/21/2014).