Southeastern and south central Minnesota and southwestern Wisconsin have extensive deposits of sand that meets the specifications required for hydraulic fracturing, or “fracking,” a drilling method used for natural gas and oil wells. Mining of these deposits has been occurring in the region for many years, however recent years have seen an increase of activity.
Sand mining in Minnesota
Minnesota state agencies collect data on the locations of silica-sand-related activities and sites. Agencies collect different data because regulatory authority over each type of activity varies between regulatory agencies. The three general activities related to silica sand are transport/load, processing, and mining.
Local governments generally have the greatest opportunity for approving and supervising sand and gravel mining operations. Local units may have additional regulations for development, operation or reclamation of a site. The MPCA and DNR do not have regulatory authority over the end use of mined silica sand.
MPCA and DNR permits may be needed (e.g., water quality, discharge and appropriation; wetlands and air emissions). The 2013 Legislature passed legislation requiring an Environmental Assessment Worksheet (EAW) for silica sand projects that meet certain size, storage, or throughput criteria. The nature of the project will determine whether the local unit of government or the MPCA is the responsible government unit (RGU for environmental review.
MPCA permits
The MPCA issues air and water permits for many sand and gravel mining operations. Some permits may have requirements specific to silica sand mining. Under certain circumstances, the MPCA may issue permits for sand storage sites.
Air permitting
MPCA air permits are issued to sand and gravel mining facilities to control air emissions from combustion sources such as dryers or particulate matter such as blowing sand. Some permits may require monitoring of particulate matter. Learn more about air quality permits.
Water permitting
MPCA water permits are issued to facilities that conduct a variety of mining activities such as sand and gravel mining. Typical pollutants regulated in sand and gravel mining discharges are total suspended solids and pH. Chemical additive use is regulated by the permit as well.
Currently permitted sand and gravel mining facilities will likely be able to also mine frac sand without modification of the existing permit. New facilities will be required to apply for permit coverage. Learn more: Wastewater permits
Health risks low
The potential air pollutants of most concern from frac sand mining are airborne particles, including particles less than 10 microns in size (PM10), particles less than 2.5 microns in size (“fine particles” or PM2.5), and crystalline silica, which ranges across both size categories.
There are two methods of determining potential health concerns from air pollution: monitoring and computer modeling. There are known health risks associated with airborne crystalline silica. However, the available information on health effects comes almost exclusively from occupational settings, where exposures are more concentrated.
There are no federal or state standards for silica concentrations in ambient air. The MPCA uses a risk guideline value for respirable crystalline silica of the particle size smaller than 4 microns to assess the potential for human health effects. This is an evolving field, and there are no generally accepted ambient monitoring method for this size. However, certain Minnesota facilities are monitoring for silica using a method adapted from common regulatory monitoring techniques. If you are interested in this method, please contact the MPCA for more information.
There also are health risks associated with other airborne particles, especially PM2.5. There are state standards for airborne particles (called Total Suspended Particles or TSP), and state and federal air quality standards for PM10 and for PM2.5. Learn more about fine particles.
2013 legislation on silica sand
A law passed in 2013 imposed new requirements for silica sand mining, processing and transportation operations in Minnesota. The law directed state agencies to provide local units of government with technical assistance on regulation and permitting. In addition, the law set new thresholds for environmental review of silica sand-related operations and required development of a number of new regulations. Resources on silica sand are consolidated on the EQB web site.