Starting in 2012 and continuing through this fall, the National Academies (NAS) are hosting workshops to inform the public about shale gas development. These workshops explore not only possible effects on air and water, but also consider health and social impacts.
Unlike NAS reports, the workshops are not consensus studies. That is, there will be a report of the proceedings or online access to copies of the presentations, but no findings, conclusions or recommendations.
Two workshops on elements of shale gas extraction have been completed and two are planned for later this year:
♦ A workshop on the “Health Impact Assessment of New Energy Sources: Shale Gas Extraction,” sponsored by the Roundtable on Environmental Health Sciences, Research and Medicine (Board on Population Health and Public Health Practice, Institute of Medicine), was held April 30-May 1, 2012. It explored the health impacts of shale gas extraction, and considered the use of health impact assessments to assess and identify ways to mitigate potential health impacts.
♦ The National Research Council (NRC), Board on Environmental Change and Society, Division of Behavioral and Social Sciences and Education has completed the first of a pair of workshops addressing risk management and governance issues in shale gas development. “Risks of Unconventional Shale Gas Development” was held May 30-31.
The workshop (described in more detail below) focused on public concerns about the risks to the environment and human health from large-scale development of shale gas.
The second workshop on governance of risks of unconventional shale gas development is planned for Aug. 15-16.
♦ “Development of Unconventional Hydrocarbon Resources in the Appalachian Basin,” a workshop hosted by the NRC, Division on Earth and Life Studies, Board on Earth Sciences and Resources, Water Science and Technology Board, is planned for late August or early September at the University of West Virginia.
The workshop will examine the geoscientific aspects of hydrocarbon development from unconventional resources, including: geology and hydrocarbon resources; potential effects on surface and groundwater quality and quantity; potential effects on landscapes, including soil and living organisms, and other environmental systems; and technical and engineering processes.
The remainder of this column will focus on many of the presentations given at the most recent workshop, “Risks of Unconventional Shale Gas Development.”
The workshop organizers stated their goal was to provide “a comprehensive, evidence-based look at the scope, nature and magnitude of environmental risks of unconventional shale gas development.”
The workshop included presentations by invited speakers and alternative comments from experts offering contrasting perspectives as speakers considered risks to air, water, public health and communities.
Industry Assessment of Risks
♦ Kris Nygaard (ExxonMobil Production), an invited presenter, summarized the sequence of operational activities involved in drilling and completing a shale gas well. Nygaard presented data showing very low risk for three widely monitored events: contamination of aquifers by hydraulic fracturing fluids, surface release or spills of chemicals, and induced seismicity.
♦ Alternate presenter and AAPG member Mark Zoback (Stanford University) described prior studies by the Secretary of Energy’s Advisory Board and the NRC, which concluded that shale gas can be developed in an environmentally responsible manner, although important environmental issues need to be solved.
♦ Alternative presenter Meagan Mauter (Carnegie Mellon University) enumerated potential risks from subsurface fluid migration, surface release of fracturing fluids, induced seismicity and truck accidents.
♦ Invited presenter Chris Moore (Desert Research Institute) reported on data gaps in the peer-reviewed literature and a severe shortage of pre-development baseline data. Moore also noted the shortage of data about the life-cycle emissions from natural gas drilling, completion, transmission and use. He described an obvious example of the uncertainties in emissions data and the need for additional study: the variation in the Environmental Protection Agency (EPA) estimates of methane emissions from natural gas systems. EPA reduced its estimated 2010 emissions by 33 percent from 2012 to 2013 reports.
♦ Alternative presenter Gabrielle Petron (NOAA) also described data limitations, noting that ozone-sampling sites are common in urban areas such as Denver, but rare in the oil fields north of Denver.
As part of NOAA’s goal to quantify actual emissions, a survey of wells operated by one company in Dish, Texas, found three of 22 wells had very high emissions, while the others were very low. This suggests operational or maintenance problems that may be easy to repair.
♦ Another alternate presenter, Tiffany Bredfeldt (Texas Commission on Environmental Quality), reported that a 2010 flyover of 5,000 storage tanks in the Barnett shale production area identified 88 sources of significant hydrocarbon emissions. The small number of problem facilities suggests that the problems can be corrected.
A study of air quality around Dish, Texas, by the Texas Department of State Health Services showed that nearly all of the documented emissions issues arose from human or mechanical failures. These items were quickly remedied and could have been avoided through increased diligence on the part of the operator.
Corrective actions amounted to little more than replacing worn gaskets, closing open hatches, and repairing stuck valves.
♦ Invited speaker Avner Vengosh (Duke University) reported that methane was found in water wells near Marcellus producing wells but not in wells far from production. Vengosh interpreted the Marcellus-related drinking-water contamination to be the result of natural gas entering the well annulus from the shale production formations or shallower formations and leaking into groundwater because of poorly constructed or failing well casings.
♦ Alternate presenter Jean-Philippe Nicot (Texas Bureau of Economic Geology) presented evidence for an alternative interpretation: Thermogenic gas in the shallow subsurface does not necessarily imply leaks – it can be natural. He cited a peer-reviewed paper in the May/June issue of the journal Groundwater, which analyzed 1,700 groundwater samples in northeastern Pennsylvania and concluded that methane concentrations are best correlated to topographic and hydrogeologic features, rather than shale gas extraction.
Public Health and Community Effects
♦ Invited presenter John Adgate (Colorado School of Public Health) reported that no comprehensive population-based studies of the public health impacts of unconventional natural gas operations have been published. Adgate also stated that recent studies, such as his organization’s health impact assessment of the Battlement Mesa area in Colorado, indicate a potential for health risks from the combination of physical, chemical and nonchemical stressors associated with the rapid change in industrial activity, population and income.
One of the findings of the Battlement Mesa study was that residents living near well completion activities had higher estimated risks for cancer and chronic non-cancer conditions, but the risks are within the EPA’s generally acceptable range.
♦ Alternate presenter David Brown (Southwest Pennsylvania Environmental Health Project) reported on a survey of adults that visited the Cornerstone Care Clinic in Burgettstown, Pa.: at least 30 percent of the 240 participants were at risk of depression, compared to the expected rate of 19 percent nationally.
♦ Another invited presenter, Jeffrey B. Jacquet (South Dakota State University), described the potential risks to communities from shale gas development. He reported on studies that show the negative impacts of a boom-and-bust economic cycle, the community discord caused by unequal distribution of economic benefits associated with rapid energy development and the health impacts of stress caused by community change.
A few ideas appeared multiple times in the presentations:
- Speakers on the technical and logistical aspects of shale gas development described low risks for water and air pollution, and induced seismicity, which could be mitigated by improved industry practices.
- Public concerns are different from documented health and safety risks.
- Baseline or pre-development data are generally lacking for air and water quality as well as social and health status.
- No data are available regarding the health or social conditions of control populations or towns without shale gas development.
- The idea that harmful health impacts are due to the psychological stress caused by rapid increases in industrial activity was widely discussed even though clinical data are lacking.