Frack sand mining boom: silica dust, air quality, and human health

by Elizabeth Grossman

“It’s basically strip mining,” said Wisconsin Department of Natural Resources (DNR) environmental engineer Rick Wulk, describing the sand mining activity that has exploded across western Wisconsin since 2010.  Mining silica and quartz and processing it into industrial sand is big business these days because this sand is an important component of hydraulic fracturing operations that extract natural gas from shale. To understand the magnitude of the current boom in sand mining, the place to look is Wisconsin.  What’s happening in Wisconsin also offers a good example of how limited current information is regarding the air quality and potential environmental health impacts of this industrial activity.

Wisconsin DNR says there are now more than 60 frack sand mining operations up and running in Wisconsin and about 40 sand processing facilities, most clustered in the western quarter of the state.  Most of these mines and processing facilities are new or newly expanded since 2010, and more are in various stages of development.  The hours worked at these Wisconsin facilities, as reported by the Mine Safety and Health Administration (MSHA), shows a distinct trend toward increased operations in the past year.

Frack sand production affects the local landscape and residents in a number of ways.  These operations are surface mines, and typically very large, many about a square mile, so there are obvious aesthetic impacts. The processing facilities also often include  impoundments or holding ponds used in sand washing operations.  In the past year there have been six ruptures at Wisconsin frack sand sites, including one that dumped large amounts of sand and sediment into the St. Croix River and its wetlands last month.  As with the fracking operations themselves, a lot of transportation is involved.  Some reportedly run hundreds of truckloads per day traveling between mine, process, storage, and long distance shipping sites. Not surprisingly, dust emanating from these operations has become a concern for communities where mines and processing facilities are located.

Dust in the air

Crystalline silica, or ground quartz dust, is a potentially serious health hazard.  People exposed to high levels of silica dust, which typically occurs occupationally, risk developing the incurable lung disease silicosis, chronic obstructive respiratory disease, bronchitis, lung cancer, scleroderma, renal disease and respiratory failure.

MSHA, the agency that enforces mine safety regulations, has a permissible exposure limit (PEL) for respirable quartz and conducts air monitoring for it during some of its biannual mine inspections.  A search of MSHA inspection records for Wisconsin sand mines shows that a number of air samples collected were below the PEL for respirable quartz.  But such MSHA air sampling for respirable quartz has apparently not been done at all of these Wisconsin mines.  And at those mines where MSHA has taken such samples, not all have yet been sampled in 2012.  Some of the Wisconsin mines have only begun operations in the past year and the MSHA data suggests they have not yet been inspected.  MSHA records for one new industrial sand mining and processing operation,  run by EOG Resources (formerly Enron Oil and Gas) that began operations in Chippewa Falls, Wisconsin in September 2011 show that MSHA has inspected the mine six times since then.  Federal mine inspectors have cited EOG for nine violations.  Among these was a citation for for exceeding the PEL for respirable quartz.  According to MSHA on-line records, the penalty  of $100, assessed in April, has not yet been paid.

While MSHA and OSHA inspect workplaces and may monitor for respirable crystalline silica, the Environmental Protection Agency (EPA) does not monitor crystalline silica dust as a hazardous air pollutant.  Instead crystalline silica is included in the particulates for which EPA monitors as what’s called either PM 10 (particulate matter of 10 microns in size) or PM 2.5.  California, Michigan, New Jersey, New York, and Texas, however, have regulations to address silica emissions but Wisconsin DNR says these states have not determined the health effects of such ambient air exposures.

Wisconsin DNR’s Wulk explained that dust control plans are part of the state’s permitting requirements for sand mining and processing facilities.  He also explained that crystalline silica dust would be captured by the state’s particulate matter monitoring so Wisconsin hasn’t seen it necessary to establish its own crystalline silica standards.  Monitoring networks in the state have not found any cause for concern regarding dust, said Wulk, so in DNR’s view, the sand mining operations appear to be controlling fine particulate matter adequately.  However, there are currently few active EPA or DNR monitoring stations located near many of Wisconsin’s sand mining and processing operations.

“We’ve shut down quite a lot of our network,” for budget reasons, said Tom Woletz of Wisconsin DNR who explained the state was not now doing any of its own monitoring of air quality impacts directly related to sand mining and processing. Chippewa County, which has become a hotbed of this activity with at least six such operations, currently has no active EPA or DNR ambient air monitors.  Nor are there any located directly in Monroe or Trempealeau counties that have comparable numbers of sand mining and processing facilities.

Concern in Chippewa County

Chippewa County is now considering monitoring ambient air for crystalline silica but no final decision has been made, said Jean Durch, Chippewa County Department of Public Health director via email. “We are in the early exploration phase of our process,” she explained.  Individual mining companies are conducting their own particulate monitoring near their sites, and Wisconsin DNR shared monitoring records for PM 10 provided to them by EOG Resources in Chippewa Falls and from Superior Sands, also located in Chippewa County.  But not all companies are doing this monitoring, explained Woletz, who also said DNR had been involved in siting of some of these monitors.

Concerned Citizens of Chippewa County, a community group that was organized to fight influx of sand mining companies, last year petitioned Wisconsin DNR to initiate rule-making to add crystalline silica to the state’s list of hazardous air pollutants and to establish an ambient air standard for this dust that would mirror one set by the California Office of Environmental Health Hazard Assessment.  That petition was denied.  The group, which explained in their petition that  many of the industrial sand sites are located near residences – some within several hundred feet – has also done its own air sampling.

That monitoring effort found that on 51 percent of the 57 sampling days, samples taken about a mile from EOG Resources Chippewa Falls facility (which is located within city limits and less than one-half mile from a child care center and near a hospital) exceeded EPA’s PM 2.5 standard.

In its August 2011 report to the Natural Resources Board, the Wisconsin DNR explained:

A recurring theme from the literature… is that very little conclusive information exists regarding sources, controls or levels of silica present in ambient air. This lack of data means it is not currently possible to determine conclusively whether or [to] what extent the quantity, duration or types of silica emissions in the state may be a public health concern. It would take significant additional efforts to fill in these data gaps. That said, Wisconsin has regulated PM for 40 years. The controls for PM are the same controls for crystalline silica. This means that for those crystalline silica sources where PM is controlled, silica emissions are also reduced.

“Companies have tried to say that there is no problem with air quality related to mines and processing plants.  People have been told this over and over,” said Pat Popple, who’s been working with Concerned Citizens of Chippewa County, in a phone conversation.  But, she says, watching the truck traffic from these plants and seeing dust blowing off the sites, people are concerned.

The National Institute for Occupational Health and Safety (NIOSH) has recently found crystalline silica exposures at fracking sites that “consistently exceeded relevant occupational criteria.” But when asked last month, NIOSH said it had not yet coordinated its investigations of these exposures with MSHA to begin to get a more comprehensive picture of occupational silica exposure throughout the fracking industry.  The monitoring and sampling conducted to date represents but a tiny fraction of the sand mining, processing and fracking operations now underway.  MSHA counts close to 30,000 people employed in industrial sand and silica mining.  But this doesn’t include workers at fracking well sites, or everyone whose work might expose them to this dust.  We also don’t yet know how many people may be exposed to this dust through ambient air in their communities.  And Chippewa County is far from the only place where people are trying to learn more about what’s in their air or to get new and more protective dust standards passed.

Note to reader: None of the sand mining companies, including US Silica, EOG Resources and Unimin, contacted responded to questions submitted by The Pump Handle. The number provided by US Silica’s website for media inquiries reached a non-working number for W.R. Grace.

Elizabeth Grossman is the author of Chasing Molecules: Poisonous Products, Human Health, and the Promise of Green Chemistry, High Tech Trash: Digital Devices, Hidden Toxics, and Human Health, and other books. Her work has appeared in a variety of publications including Scientific American, Salon, The Washington Post, The Nation, Mother Jones, Grist, and the Huffington Post. Chasing Molecules was chosen by Booklist as one of the Top 10 Science & Technology Books of 2009 and won a 2010 Gold Nautilus Award for investigative journalism.