The mining and transport of proppant sand are drawing controversy similar to that related to the content and handling of hydraulic fracturing (fracking) fluids if recent events are an indication.

While sand comes from mines around the country, Wisconsin and Minnesota could be considered the heart of frack sand country.

In western Wisconsin, Trempealeau County is said to have issued more frack sand mining permits than any other county in either Wisconsin or Minnesota. But in recent days, the Trempealeau County Board voted to impose a moratorium of up to one year on new frack sand mining facilities. This came after the county had approved permits for 26 companies mining and processing silica sand, according to local news reports. Now county officials want to research health issues related to mining operations.

Dust from sand mining can cause a host of respiratory ills to which mine workers have long been at risk. As mining operations proliferate, residents near mines are growing increasingly concerned about air quality as well as increased railroad and truck traffic in their neighborhoods. The industry generally counters that mining does not pose a threat to the public as emissions are controlled for the benefit of mine workers and area residents.

Trade group Wisconsin Industrial Sand Association maintains that its members “implement strict policies to eliminate any potential adverse health effects associated with occupational silica exposure. That includes having in place strict performance practices to control dust generation and using advanced technology and equipment to control air emissions from our operations.”

The issues surrounding air monitoring in sand mining regions are similar to those related to emissions monitoring in areas where there are tank batteries and natural gas compressors. Those skeptical of sand mining’s safety for the public worry that air monitors are not placed correctly or fail to provide an accurate representation of the volume of microscopic sand particles the public is actually breathing.

According to the U.S. Geological Survey, the Ordovician St. Peter Sandstone in the Midwest has been the primary source of silica sand for many uses, particularly that used for proppant. “Mined in five states, frack sand from the St. Peter Sandstone is within reasonable transport distance to numerous underground shale formations producing natural gas,” the government agency said in its “2011 Minerals Handbook,” its most recent. “In 2011, 59% of frack sand was produced in the Midwest…In 2011, sales of frack sand increased by 77% compared with those of 2010.”

Meanwhile in Minnesota, the state’s Department of Natural Resources (DNR) is currently seeking publiccomment on proposed rules regulating silica sand minelands and facilities. The move comes at the behest of the state legislature. Minnesota DNR also will be seeking comment on a proposal for a trout stream setback permit for sand projects within the Paleozoic Plateau. “The rulemaking process and timelines will be dictated by the complexity level of the issues that arise and potentially expand comment periods to accommodate higher levels of public involvement,” the agency said.

Earlier this year in the city of Winona, MN, the sand moratorium expired and was followed by new ordinancesapplying to sand mining and related activities within the city.