Bench & Bar of Minnesota is the official publication of the Minnesota State Bar Association.

There’s Sand in Them Thar Hills: Minnesota Races to Regulate Frac Sand Mining

“Not all that tempts your wand’ring eyes

And heedless hearts, is lawful prize;

Nor all that glisters, gold.”1


The silica or “frac” sand boom in Minnesota appeared to have all the makings of a modern gold rush: extensive sand supplies, rabid demand, national media coverage, speculators offering to pay multiple times market value for small sand-bearing lots. But following widespread citizen outcry about potential environmental and health risks of frac sand mining, Minnesota regulators hit the brakes. Sand-rich counties passed sand mining moratoriums. The state legislature mandated additional environmental safeguards and ordered agency rulemaking.

Now the moratoriums have been lifted and the frac sand boom in Minnesota is finally, cautiously, moving ahead. Whether you view Minnesota’s approach to regulating silica sand as sound environmental policy or job-killing bureaucracy, one thing is certain: the frac sand industry in Minnesota is subject to a dizzying array of still-evolving environmental laws, most of them implemented by local governments with, until very recently, little consistency from county to county.

Beach & Boom

Sand. Miles and miles of toe-curling sand. Bordering an unending blue ocean. Welcome to Paleozoic-era southeastern Minnesota, circa 500 million BC. Most of North America is covered by a shallow sea, but here is a beach, with sand grains composed almost entirely of quartz, a hard, inert mineral based on the chemical silica.2 As the sea level fluctuated over the millennia, the beach moved back and forth, creating layers of quartz or “silica” sandstone, which was eventually entombed beneath a massive hard-rock cap.

Fast forward a few hundred million years to the early 20th century. Rivers and glaciers have steadily eroded the rocky cap, revealing the buried Paleozoic sandstone and providing residents of southeastern Minnesota with abundant supplies of silica sand conveniently close to the surface—accessible, in many cases, with no more than a shovel. The sand proved useful for many applications, including livestock bedding, glass making, abrasives, foundry sands, and water filtration systems, and before long dozens of mom-and-pop sand operations cropped up to meet these needs.

For most of its sleepy, century-old existence, Minnesota’s silica sand industry has been uncontroversial. But an extraction revolution began a decade ago when energy companies began actively expanding “unconventional” natural gas and oil resources in places like Texas, Pennsylvania, and North Dakota.3 There are no oil or gas fracking operations in Minnesota.

Refinements of two key technologies make it feasible for developers to tap these previously inaccessible resources. First, horizontal drilling allows wells to snake their way along horizontal formations thousands of feet below the surface, providing greater exposure to the fossil fuel-bearing rock. Second, hydraulic fracturing (or “fracking”) releases the trapped gas or oil.4 Fracking involves pumping water and chemicals into a well at a pressure high enough to crack or “fracture” the surrounding impermeable rock formation. However, to prevent the fractures from simply collapsing, developers must also pump a “proppant” into the wells to “prop” open the fractures and keep the gas or oil flowing.

As it turns out, silica sand makes an ideal proppant—crush-resistant, well-rounded, relatively large grains, abundant supplies—and has become the industry standard. Fracking requires a staggering amount of sand, often thousands of tons per well. Not surprisingly then, the fracking boom has been accompanied by a parallel boom in silica sand mining.5 Minnesota is currently the fourth largest silica sand producer in the U.S., trailing only Texas, Illinois, and Wisconsin.6

 Silica Sand Mines

All existing silica sand mines in Minnesota are above ground. The nature of the mining techniques used to access silica sand in these quarries depends upon the geologic and hydrologic conditions. There are two main regions in Minnesota where silica sand resources are relatively easily accessible. The first is the so-called “Paleozoic Plateau,” a bedrock-dominated, erosional landscape in far southeastern Minnesota between the Mississippi River corridor south of the Twin Cities and extending just west of Rochester.7 Here, “knobs” or mesas containing silica sand layers rest on top of the plateau; the sand mines excavate these elevated areas down to the level of the surrounding landscape. This technique is known as “dry mining” because the mines
generally exist above the water table.

In Minnesota’s second principal silica sand region, a mile-wide swath running along the Minnesota River Valley between Mankato and the Twin Cities, the predominant method is known as “wet mining.” In this region, the most accessible sand resources are located between the flood plain and the bluffs. Excavations in these areas are below the existing grade of the landscape and below the water table—i.e., “wet”—and often require blasting and dewatering.

Before silica sand can be used as a proppant for fracking, it must be processed to extract particles of uniform shape and size. Processing silica sand generally entails washing the raw sand, separating out the fine particles, and then drying the desired particles with blasts of hot air. At that point, the sand is ready to be transported.

Although there are many silica sand quarries in Minnesota—as many as 30 in some counties—most of these are small operations selling sand for livestock bedding, as they have done for decades. Only a half-dozen mines are actually producing sand for use in fracking. 8 By contrast, in Wisconsin, which has similar silica sand resources to Minnesota’s, there are many more.9 This difference is partly due to geology and partly due to logistics. But Minnesota’s silica sand industry’s slower growth is in large part due to the fact that Minnesota regulators have taken a much more cautious approach to authorizing new or expanded mines.

Citizen Outcry

Minnesota’s hesitation in authorizing new silica sand mines derived primarily from public outcry at the looming proliferation of frac sand mines. Cities in southeastern Minnesota suddenly found their council meetings packed with citizens opposed to proposed frac sand mines. The citizens cited multifarious potential impacts to human health and the environment from large-scale silica sand mining, including the risk of groundwater contamination, exposure to silica dust, and increased truck traffic on rural roads. With weak or nonexistent mining ordinances, these local governments were generally ill-equipped to address the citizens’ concerns. Some passed moratoriums, most of which have now expired, prohibiting new or expanded mines.

Anti-mining citizen groups also appealed to the Minnesota Legislature, which in May 2013 responded by adopting HF 976,10 establishing a framework for state-level regulations specifically addressing silica sand mining. The legislation tasked Minnesota’s Environmental Quality Board (“EQB”) with assisting local governments by developing a “toolkit” of model standards for silica sand mining, processing, and transportation which local governments can utilize. EQB published the final “Tools to Assist Local Governments in Planning for and Regulating Silica Sand Projects” in March 2014. HF 976 also directed EQB to revise the environmental review thresholds for silica sand, and the legislation set interim standards more stringent than preexisting ones.

HF 976 tasked three other state agencies with rulemaking related to the environmental impacts of silica sand mining projects. It required the Department of Natural Resources (“DNR”) to adopt rules pertaining to site reclamation, it tasked the Minnesota Pollution Control Agency (“MPCA”) with adopting rules regulating particulate emissions from silica sand projects, and it directed the Department of Health (“MDH”) to adopt an air quality health-based value (“HBV”) for silica sand. In July 2013, MDH established a silica sand HBV of three micrograms per square meter (3µg/m3) for respirable crystalline silica. The other agencies have yet to promulgate rules. Finally, the legislation established a one-mile setback for silica projects from all trout streams in southeastern Minnesota unless the project obtains a DNR silica sand trout mining setback permit.11

Impacts and Regulation

Amid this flurry of lawmaking it is easy to forget that silica sand mining projects are already subject to a complex web of existing federal, state and local environmental laws. Together, these laws address five principal areas of concern associated with silica sand mining:  environmental review, air pollution, water pollution, transportation, and neighborhood nuisance issues.

Environmental Review: Rules developed by the EQB under Minnesota’s Environmental Policy Act, Minn. Stat. ch. 116D, establish categories of projects for which the “responsible governmental unit” (“RGU”), prior to authorizing the project, must study the potential impacts on the environment. The first step in this process is to prepare an Environmental Assessment Worksheet (“EAW”), a standardized worksheet designed to screen projects for environmental concerns.  If, on the basis of an EAW, the RGU determines a project has the “potential for significant environmental effects,” the RGU must prepare an Environmental Impact Statement (“EIS”), a significantly more rigorous (and expensive) study of the project’s environmental impacts.

In the case of proposed silica sand mining projects, the EQB rules require an EAW if the project: (1) is expected to excavate 20 or more acres of land to a depth of ten feet or more; (2) will be capable of storing more than 7,500 tons of silica sand; or (3) will have an annual throughput of more than 200,000 tons of silica sand. In HF 976, the legislature added several new items that must be included in silica-sand EAWs, including a hydrogeologic investigation to determine risks of water pollution, an assessment of available water resources, an air quality impact assessment, and a traffic impacts study. According to the EQB, on the basis of EAWs, at least 11 existing or proposed silica sand facilities in southeastern Minnesota were found to have “potential for significant environmental effects,” requiring preparation of an EIS.

Air Pollution: No environmental issue associated with the frac sand boom has been more intensely debated than air pollution; specifically, the potential health risks of silica dust in the ambient air of communities near silica sand operations. Mining silica sand produces a lot of dust. Under certain circumstances, this sand dust contains respirable crystalline silica (“RCS”), small silica dust particles less than four micrometers in diameter (known as “PM4”), which, when inhaled are deposited deep into the lungs. Prolonged and excessive exposure to RCS causes a variety of health problems, including silicosis, increased risk of lung infections, obstructive lung disease, and lung cancer. For this reason, OSHA has set strict workplace exposure limits for RCS.12

Most of the information about the health effects of RCS exposure comes from studies of workers who were exposed to high levels of RCS at work for many years in enclosed environments like underground mines. By contrast, very little is known about the health risks from exposure to RCS in outdoor ambient air.

Minnesota has air quality standards governing overall levels of dust or “particulate matter” (“PM”) but no standards establishing safe levels of RCS in the ambient air.13  The Minnesota Pollution Control Agency (“MPCA”) enforces the standards, which include silica dust as a component of overall PM, through air emissions permits for silica sand mining facilities. Facilities may also have to comply with dust-control measures specified in county or municipal permits, such as applying water to mine-site roads and sand stockpiles.

Although the general PM standards will control some emissions of silica sand, they are not designed to address the unique health risks posed by RCS. Respirable crystalline silica particles, four micrometers in diameter or less, are small enough to be “respirable” and cause silicosis, but they are regulated under a standard for particles up to ten micrometers in diameter (PM10) rather than the stricter standard for particles smaller than 2.5 micrometers (PM2.5). MPCA’s upcoming rulemaking may result in silica-specific air standards. In the meantime, MPCA has indicated that it will rely upon the MDH’s chronic Health Based Value for PM4 size silica particles in nonoccupational exposure to RCS of 3µg/m3.14 While this is not an enforceable standard on its own, it can become an enforceable standard if included within a facility’s permit.15

Water Pollution and Use: Public debate about the silica sand boom has focused not only on air pollution but also possible threats to Minnesota’s lakes, streams and wetlands, as well as groundwater. For example, the initial removal of rock and topsoil at a mine site can put groundwater quality at risk. The Karst geological landscape in southeastern Minnesota, with its sinkholes and underground drainage systems, renders the underlying aquifers particularly vulnerable to mine-related contaminants. And mine dewatering in the Minnesota River Valley region can create new pathways for shallow groundwater contaminants to migrate to deeper aquifers.

MPCA regulates silica sand facilities’ discharges to surface and ground water primarily through a permitting process under the Clean Water Act, imposing limits on the amounts of specified pollutants a facility may emit into nearby lakes and rivers as well as ongoing obligations to test for water quality. Prior to discharging process wastewaters, silica sand facilities generally must also first collect the water in on-site treatment ponds and allow sediments and other pollutants to settle to the pond bed. Regulatory authorities will also attempt to minimize discharges of stormwater—precipitation contaminated with mining materials such as processed silica sand or chemicals—by requiring enclosure of mining processes and collection of stormwater in on-site containment basins.

If construction of  a new or expanded silica sand mine will require filling in or completely removing swamps or other wetlands, additional permits from the U.S. Army Corps of Engineers or the Minnesota Board of Water and Soil Resources (“BWSR”) likely will be required. The Corps has authority under section 404 of the federal Clean Water Act to issue permits to discharge dredge or fill material or excavate within waters or wetlands of the United States. Section 404 permits are subject to numerous prerequisites, including EPA approval of the permit. If the development of a mine will impact wetlands not subject to the Corps’ 404 jurisdiction, the local government approving the project must review the proposal pursuant to BWSR rules. In both cases, the mine operator may be required to “mitigate” lost wetlands by creating similar wetlands at other locations.

Finally, silica sand facilities can have significant effects upon water quantity. Large silica sand operations use substantial amounts of water for washing and filtering the sand and for controlling fugitive dust from roads and sand piles. This intense water usage has the potential to reduce flows to wetlands, streams, and lakes and even to impact public water supplies in local wells.

The Minnesota Department of Natural Resources (“DNR”) administers the use and allocation of all Minnesota waters, including both surface water and groundwater. If a silica sand facility consumes more than 10,000 gallons of water per day or 1 million gallons per year, it must obtain a water “appropriations” permit from DNR.  This can be a complicated process, requiring preparation of a reclamation plan, a domestic well impact study, a wetlands delineation map, a hydrogeological investigation, and an aquifer testing report.16 And before granting the permit, DNR must determine that the facility’s plans will not adversely affect higher priority water uses, such as domestic water supply and agricultural irrigation.

Transportation: An oft-cited grievance about increased silica sand mining is that it will cause a quantum leap in truck traffic associated with transporting sand. Whereas citizens, as outlined previously, are concerned about exposure to silica dust from these trucks, local governments are concerned about wear and tear on their roads.  And with good reason.

According to a recent study, if the load on a roadway is increased by 20 percent (e.g., heavy trucks), damage to the road can increase by as much as 50 percent.17 To put this in context, a single silica sand mine can produce 270,000 tons of sand per year, requiring 11,740 trucks per year. A typical local county roadway is designed for just 50,000 trucks over its lifetime.18  To help pay for this damage, some counties have instituted the
Aggregate Material Production Tax provided for under Minn. Stat. §298.75. This tax, which is in addition to any sales tax, is imposed upon producers and importers of “aggregate material,” which includes silica sand, at a rate of 21.5 cents per cubic yard, with the proceeds used for maintenance, construction, and reconstruction of roads and bridges and for mine site reclamation. In addition to the aggregate tax, local governments can attempt to ameliorate roadway damage through the permitting process; for example, imposing conditions in mining permits requiring companies to transport silica sand using specific hauling routes.

Neighborhood Nuisance: Given the choice, most people would rather not live beside an industrial facility, including silica sand mines and processing plants. The list of disturbances and inconveniences silica sand operations can pose to neighboring residents is a long one, ranging from loud noise to vibrations from blasting, aesthetic insults, and dangerous “attractive nuisance” conditions.  Most neighborhood nuisance issues are regulated at the local level through zoning and other ordinances. Additionally, permits issued by local governments often contain requirements to reduce impacts upon neighboring landowners.

Mines don’t last forever, and citizens and local governments have understandable concerns about what happens to mining facilities when the mining project is complete or when an operator goes bankrupt. Abandoned mine sites and processing plants present many potential dangers to the surrounding communities, not the least of which is residual pollution. The sites must be “reclaimed,” restored to a safe condition. Although DNR has substantial rules governing the reclamation of taconite and copper mine sites following closure of operations, there are no such state rules for sand mines. As noted, HF 976 directed DNR to pass rules regarding silica sand mine reclamation. In the interim, as with so many other aspects of silica sand regulation, local permitting authorities are left with the task of establishing standards for restoring abandoned silica mine sites and ensuring operators provide sufficient financial assurance to cover the costs.

Final Thoughts

The Minnesota frac sand industry is indeed experiencing a period of rapid growth, but it has hardly been a boom—more like someone slowly turning up the volume: a “Minnesota Nice” gold rush. The methodical approach state and local governments have taken to permitting new silica sand projects has pleased no one: too cautious for frustrated would-be developers; not cautious enough for anti-mining citizen groups. And with the burden of implementing a veritable archipelago of environmental regulations falling mainly on the shoulders of local governments, regulation of silica sand can vary significantly from one county to the next. Yet, as state agencies look toward passing new silica sand regulations, and with EQB’s Toolkit providing uniform guidance to local governments, there is at least the promise of a more consistent, statewide approach to regulating the environmental impacts of silica sand mining. Which, at the end of the day, cautious or otherwise, may be in the best interest of all.

Jeremy Greenhouse is a partner at The Environmental Law Group, Ltd., which he joined in 2012, having previously practiced with Dorsey & Whitney and with Greenhouse & Gram.  He has represented clients in a wide range of environmental law matters, with a focus on water law and the mining industry, handling complex litigation in federal and state courts and arguing before the Minnesota Court of Appeals. 

Susan Wiens is of counsel with the Environmental Law Group, Ltd., having joined the firm in February 2014. Before joining the firm, Susan was a partner at Greene Espel, PLLP and an executive officer of an arbitration service provider.  She provides counsel in environmental litigation, permitting and regulatory compliance matters. 


Leave a Reply

Articles by Issue

Articles by Subject