Environmental impact of fracking in the United States

Main articles: Environmental impact of hydraulic fracturing and Hydraulic fracturing in the United States

Environmental concerns with hydraulic fracturing of shale include the potential contamination of ground water, risks to air quality, the potential migration of gases and hydraulic fracturing chemicals to the surface, the potential mishandling of waste, and the health effects of these, such as cancer. Many cases of suspected groundwater contamination have been documented. With the explosive growth of natural gas wells in the US, science writer Valerie Brown predicted in 2007 that "public exposure to the many chemicals involved in energy development is expected to increase over the next few years, with uncertain consequences." As early as 1987, researchers at the United States Environmental Protection Agency (EPA) concluded that the hydraulic fracturing process can and has contaminated groundwater. According to allegations from former EPA employees, the evidence showing the negative environmental impact of fracking was systematically removed from congressional reports to support the energy industry under the direction of the Office of Legal Counsel during the Reagan administration.

Schematic depiction of hydraulic fracturing for shale gas, showing potential environmental effects.

Research

Illustration of hydraulic fracturing and related activities

Interviews with Environmental Protection Agency (EPA) scientists and leaked documents have shown that, since the 1980s, EPA investigations into the oil and gas industry's environmental impact—including the ongoing one into fracking's potential impact on drinking water—and associated reports had been narrowed in scope and/or had negative findings removed due to industry and government pressure. The most recent example of this concerns the 2012 EPA Hydraulic Fracturing Draft Plan. Despite concerns about the elevated levels of iodine-131 (a radioactive tracer frequently used in hydraulic fracturing according to Halliburton and other company patents of the process) in drinking water and milk in areas near hydraulic fracturing sites, iodine-131 is not listed among the chemicals to be monitored in the draft plan for the study. Other known radioactive tracers used in hydraulic fracturing but not listed as chemicals to be studied include radioactive isotopes of gold, xenon, rubidium, iridium, scandium, and krypton.[6]

A New York Times report claimed that an early draft of a 2004 EPA study discussed "possible evidence" of aquifer contamination but the final report omitted that mention. Some have also criticized the narrowing of EPA studies, including the EPA study on hydraulic fracturing's effect on drinking water to be released in late 2014. In addition, after court cases concerning contamination from hydraulic fracturing are settled, the documents are sealed, and gag orders issued, reducing the information available about contamination. The American Petroleum Institute denies that this practice has hidden problems with gas drilling.

Health effects

One study suggests that hydraulic fracking is sickening and killing cows, horses, goats, llamas, chickens, dogs, cats, fish and other wildlife, as well as humans. The study covered cases in Colorado, Louisiana, New York, Ohio, Pennsylvania and Texas. The case studies include reports of hundreds of cows dying as well as stillborn and stunted calves after exposure to hydraulic fracturing spills from dumping of the fluid into streams and from workers slitting the lining of a wastewater impoundment (evaporation ponds) so that it would drain and be able to accept more waste. The wastewater then drained into a pasture and a pond. The study noted that it was difficult to assess health impact because of the industry's strategic lobbying efforts that resulted in legislation allowing them to keep the proprietary chemicals in the fluid secret, protecting them from being held legally responsible for contamination. Bamberger stated that if you don't know what chemicals are, you can't conduct pre-drilling tests and establish a baseline to prove that chemicals found postdrilling are from hydraulic fracturing. The researchers recommended requiring disclosure of all hydraulic fracturing fluids, that nondisclosure agreements not be allowed when public health is at risk, testing animals raised near hydraulic fracturing sites and animal products (milk, cheese, etc.) from animal raised near hydraulic fracturing sites prior to selling them to market, monitoring of water, soil and air more closely, and testing the air, water, soil and animals prior to drilling and at regular intervals thereafter.

Early in January 2012, Christopher Portier, director of the US CDC's National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry, argued that, in addition to the EPA's plans to investigate the impact of fracking on drinking water, additional studies should be carried out to determine whether wastewater from the wells can harm people or animals and vegetables they eat. A week later, a group of US doctors called for a moratorium on fracking in populated areas until such studies had been done.

Air quality

The methane emissions from wells raise global warming concerns, but other incidents have raised concerns about volatile organic contaminants (VOCs) and ozone, For example, one study found elevated levels of disulfides, benzene, xylenes and naphthalene near compressor stations and another found health complaints in those residing near gas wells, although cause and effect was not established. Another study found no health effects.

On April 17, 2012, the U.S. Environmental Protection Agency (EPA) issued cost-effective regulations, required by the Clean Air Act, to reduce harmful air pollution from the oil and natural gas industry while allowing continued, responsible growth in U.S. oil and natural gas production. The final rules include the first federal air standards for natural gas wells that are hydraulically fractured, along with requirements for several other sources of pollution in the oil and gas industry that currently are not regulated at the federal level. Based on public comment, EPA made a number of changes to the proposed rules to increase compliance flexibility while maintaining comparable environmental benefits, streamline notification, recordkeeping and reporting requirements, and strengthen accountability.

The final rules are expected to yield a nearly 95 percent reduction in VOC emissions from more than 11,000 new hydraulically fractured gas wells each year. This significant reduction would be accomplished primarily through capturing natural gas that currently escapes into the air, and making that gas available for sale. The rules also will reduce air toxics, which are known or suspected of causing cancer and other serious health effects, and emissions of methane, a potent greenhouse gas.

Global warming

The main hydraulic-fracturing-related air emissions are methane emissions during hydraulic fracturing, from well completions, from piping leaks, and by equipment such as compressor stations. Whether natural gas produced by hydraulic fracturing causes higher well-to-burner emissions than gas produced from conventional wells is a matter of contention. A 2012 report coauthored by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory found emissions from shale gas, when burned for electricity, were “very similar” to those from conventional well natural gas, and less than half the emissions of coal.

Several studies which have estimated lifecycle methane leakage from shale gas development and production have found a wide range of leakage rates, from less than 1% of total production to nearly 8%. Using data from the Environmental Protection Agency’s most recent Greenhouse Gas Inventory yields a methane leakage rate of about 1.4%, down from 2.3% from the EPA’s previous Inventory.

The most comprehensive study of methane leakage from shale gas to date, initiated by the Environmental Defense Fund (EDF) and released in the Proceedings of the National Academy of Sciences on September 16, 2013, finds that fugitive emissions in key stages of the natural gas production process are significantly lower than estimates in the EPA’s national emissions inventory (which are already quite low). The study reports direct measurements from 190 onshore natural gas sites across the country and estimates a leakage rate of 0.42% for gas production. Although the EDF study did not cover all stages of natural gas supply chain, subsequent studies are planned to estimate leakage rates in others parts of the system.

The study which found the highest methane leakage rate, conducted by professor Robert W. Howarth et al. of Cornell University, found that "3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the lifetime of a well." According to the study, this is at least 30% and perhaps even 100% more than from conventional gas production. The study explains these higher emissions with hydraulic fracturing and drill out following the fracturing. Methane gradually breaks down in the atmosphere, forming carbon dioxide. It means its greenhouse-gas footprint is worse than coal or oil for timescales of less than fifty years. However, several studies have argued that the paper was flawed and/or come to completely different conclusions, including assessments by experts at the US Department of Energy, by Carnegie Mellon University and the University of Maryland, as well as by the Natural Resources Defense Council, which concluded that the Howarth et al. paper's use of a 20-year time horizon for global warming potential of methane is "too short a period to be appropriate for policy analysis." In January 2012, Howarth's colleagues at Cornell University responded with their assessment that the Howarth paper was "seriously flawed" because it "significantly overestimate[s] the fugitive emissions associated with unconventional gas extraction, undervalue[s] the contribution of 'green technologies' to reducing those emissions to a level approaching that of conventional gas, base[s] their comparison between gas and coal on heat rather than electricity generation (almost the sole use of coal), and assume[s] a time interval over which to compute the relative climate impact of gas compared to coal that does not capture the contrast between the long residence time of CO₂ and the short residence time of methane in the atmosphere." The authors of that response conclude that "shale gas has a GHG footprint that is half and perhaps a third that of coal," based upon "more reasonable leakage rates and bases of comparison." Howarth et al. responded to this criticism: "We stand by our approach and findings. The latest EPA estimate for methane emissions from shale gas falls within the range of our estimates but not those of Cathles et al, which are substantially lower."

Piceance Basin, Colorado

In Garfield County, Colorado, another area with a high concentration of drilling rigs, volatile organic compound emissions increased 30% between 2004 and 2006; during the same period there was a rash of health complaints from local residents. Epidemiological studies that might confirm or rule out any connection between these complaints and fracking are virtually non-existent. In 2012, researchers from the Colorado School of Public Health showed that air pollution caused by fracking may contribute to "acute and chronic health problems" for those living near drilling sites.

The Colorado Oil & Gas Conservation Commission has found some wells containing thermogenic methane due to oil and gas development upon investigating complaints from residents. Individuals "smell things that don't make them feel well, but we know nothing about cause-and-effect relationships in these cases." In Garfield County, Colorado, another area with a high concentration of drilling rigs, volatile organic compound emissions increased 30% between 2004 and 2006; during the same period there was a rash of health complaints from local residents. Epidemiological studies that might confirm or rule out any connection between these complaints and fracking are virtually non-existent. The health effects of VOCs are largely unquantified, so any causal relationship is difficult to ascertain; however, some of these chemicals are suspected carcinogens and neurotoxins. Investigators from the Colorado School of Public Health performed a study in Garfield regarding potential adverse health effects, and concluded that residents near gas wells might suffer chemical exposures, accidents from industry operations, and psychological impacts such as depression, anxiety and stress. This study (the only one of its kind to date) was never published, owing to disagreements from local health officials and the industry about the study's methods.

Groundwater

See also: List of additives for hydraulic fracturing

Hydraulic fracturing uses between 1.2 and 3.5 million US gallons (4.5 and 13.2 Ml) of water per well, with large projects using up to 5 million US gallons (19 Ml). Additional water is used when wells are refractured. An average well requires 3 to 8 million US gallons (11,000 to 30,000 m³) of water over its lifetime. Back in 2008 and 2009 at the beginning of the shale boom in Pennsylvania, hydraulic fracturing accounted for 650 million US gallons per year (2,500,000 m³/a) (less than 0.8%) of annual water use in the area overlying the Marcellus Shale. The annual number of well permits, however, increased by a factor of five and the number of well starts increased by a factor of over 17 from 2008 to 2011. A report by Ceres questions whether the growth of hydraulic fracturing is sustainable in Texas and Colorado. The report integrated well location and water use data from FracFocus.org with World Resources Institute's (WRI) water risk maps. Ninety-two percent of Colorado wells were in extremely high water stress regions and 51% percent of the Texas wells evaluated were in high or extremely high water stress regions. "Extremely high water stress" means that more than 80% of the available water is already allocated for agricultural, industrial and municipal water use.

In Barnhart, Texas the aquifer ran dry because of industrial hydraulic fracturing: one landowner had 104 water wells (designed to supply fracking) dug into his land by his fracker tenants, and the population is left with little recourse for their dry taps. In the Spring of 2013, new hydraulic fracturing water recycling rules were adopted in the state of Texas by the Railroad Commission of Texas. The Water Recycling Rules are intended to encourage Texas hydraulic fracturing operators to conserve water used in the hydraulic fracturing process for oil and gas wells.

While the EPA recognizes the potential for contamination of water by hydraulic fracturing, in May 2011 EPA Administrator Lisa P. Jackson testified in a Senate Hearing Committee stating "I'm not aware of any proven case where the fracking process itself has affected water...". One reason for a seeming lack of documentation is the current practice of sealing the documents after a court case. While the American Petroleum Institute "dismissed the assertion that sealed settlements have hidden problems with gas drilling," some feel it represents an unnecessary risk to public safety and health. Despite these setbacks, there are, however, cases of contamination have been documented both before and after her testimony.

In 2009 state regulators from at least a dozen states stated that they have seen no evidence of the hydraulic fracturing process polluting drinking water. In 2011, former U.S. EPA administrator Lisa P. Jackson (appointed by President Barack Obama) repeatedly said that the EPA had never made a definitive determination of contamination by the hydraulic fracturing process. By August 2011 there were at least 36 cases of suspected groundwater contamination due to hydraulic fracturing in the United States. In April 2013, Dr. Robin Ikeda, Deputy Director of Noncommunicable Diseases, Injury and Environmental Health at the CDC testified to congress that EPA had documented contamination at several sites. In several cases EPA has determined that hydraulic fracturing was likely the source of the contamination.

Researchers at the University of Texas at Arlington, Arlington, Texas evaluated private well water quality in aquifers overlying the Barnett Shale formation. Arsenic, selenium, strontium and total dissolved solids (TDS) levels in some wells within 3 km of active wells exceeded EPA MCLs. Levels of arsenic, selenium, strontium, and barium were lower at comparison sites located outside of 3 km from the wells, as well as outside the Barnett Shale region. Methanol and ethanol were found in 29% of samples. Researchers attributed the elevated levels to a variety of factors, including mobilization of natural constituents, the lowering of the water table, and faulty equipment.

2004 EPA study

A 2004 study by the EPA concluded that the injection of fracking fluids into coalbed methane (CBM) wells posed a minimal threat to underground drinking water sources. An early draft of the study discussed the possibility of dangerous levels of fracking-fluid contamination, and mentioned "possible evidence" of aquifer contamination; both these points were absent from the final report, which concluded that fracking "poses little or no threat to drinking water". An agency whistle-blower said shortly after publication that the absence could be explained by strong industry-influence and political pressure. The scope for the study focused on the injection of fracking fluids, while ignoring other aspects of the process such as disposal of fluids, and environmental concerns such as surface water quality, fish kills and acid burns; the study was also concluded before public complaints of contamination started emerging. In 2005, hydraulic fracturing was exempted by US Congress from any regulation under the Safe Drinking Water Act, possibly due to this EPA report.

However, it is important to note that not every instance of groundwater methane contamination is a result of hydraulic fracturing. Often, local water wells drill through many shale and coal layers that can naturally seep methane into the producing groundwater. This methane is often biogenic (created by organic material decomposition) in origin as opposed to thermogenic (created through "thermal decomposition of buried organic material"). Thermogenic methane is the methane most often sought after by oil & gas companies deep in the earth, whereas biogenic methane is found in shallower formations (where water wells are typically drilled). Through isotope analysis and other detection methods, it is often fairly easy to determine whether the methane is biogenic or thermogenic, and thus determine from where it is produced.

University of Texas study

Proponents of hydraulic fracturing have incorrectly reported in the press and other media that the recent University of Texas Study ("Fact-Based Regulation for Environmental Protection in Shale Gas Development") found that hydraulic fracturing caused no environmental contamination, when in fact the study found that all steps in the process except the actual injection of the fluid (which proponents artificially separated from the rest of the process and designated "hydraulic fracturing") have resulted in environmental contamination. The radioactivity of the injected fluid itself was not assessed in the University of Texas study. The other stages or "phases of the shale gas development life cycle" into which hydraulic fracturing has been divided in various reports are (1) drill pad construction and operation, (2) the construction, integrity, and performance of the wellbores, (3) the flowback of the fluid back towards the surface, (4) blowouts and spills, (5) integrity of other pipelines involved and (6) the disposal of the flowback, including waste water and other waste products. These stages were all reported to be sources of contamination in the University of Texas study. The study concluded that if hydraulic fracturing is to be conducted in an environmentally safe manner, these issues need to be addressed first. The distortion seemed only to be the focus on the injection stage. The study's objectivity was later called into question because Groat failed to disclose his energy industry ties.

There are extensive links between UT and the oil & gas industry, with the giving of Royal Dutch Shell to the university currently standing at more than $24.8 million, $4m alone having been handed over for 2012. Since 2011, Shell has partnered Texas in a program called Shell-UT Unconventional Research, and the university has a similar research program in place with Exxon Mobil. Halliburton, the largest supplier of fracking services in the United States, has also given millions of dollars to the university. Statoil announced a $5m research agreement (part of which will focus on oil shale) with UT's Bureau of Economic Geology in September 2011. The study concluded that if hydraulic fracturing is to be conducted in an environmentally safe manner, these issues need to be addressed first.

The University of Texas Study described the environmental impact of each of the separate parts of the overall hydraulic fracturing process, or "phases of the shale gas development life cycle." These parts include of (1) drill pad construction and operation, (2) the construction, integrity, and performance of the wellbores, (3) the injection of the fluid once it is underground (which proponents consider the actual "fracking"), (4) the flowback of the fluid back towards the surface, (5) blowouts, often unreported, which spew hydraulic fracturing fluid and other byproducts across surrounding area, (5) integrity of other pipelines involved and (6) the disposal of the flowback, including waste water and other waste products. Associated problems include (1) Groundwater Contamination, (2) Blowouts and House Explosions, (3) Water Consumption and Supply, (4) Spill Management and Surface Water Protection, (5) Atmospheric Emissions, (6) Health Effects Proponents have reported that groundwater contamination doesn't come directly from the "fracking" part of the process (the injection of hydraulic fracturing chemicals into Shale rock formations) but from other parts of the hydraulic fracturing process, such as leaks in its fluid or waste storage apparatus. One review says that methane in well waters in some areas probably comes from natural sources. Injection cannot be accomplished, however, without the accompanying stages. Wellbores and pipelines can have faulty construction or be damaged during the process, allowing the fluid to flow into aquifers. The waste water evaporation ponds allow the volatile chemicals in the waste water to evaporate into the atmosphere. The ponds may overflow when it rains, and the runoff will eventually makes its way into groundwater systems. Groundwater may become contaminated when poorly constructed pipelines used to transport the waste water to water treatment plants leak or break, allowing the waste water and fracking chemicals to flow into groundwater systems. The transportation by trucks and storage of fracking chemicals allows for groundwater to become contaminated when accidents happen during transportation to the fracking site or to its disposal destination. Disposal of fracking fluid by injection can cause earthquakes, and release of unprocessed or under-processed waste water into rivers can contaminate water supplies.

In 2010 the film Gasland premiered at the Sundance Film Festival. The filmmaker claims that chemicals including toxins, known carcinogens, and heavy metals polluted the ground water near well sites in Pennsylvania, Wyoming, and Colorado. The film was criticized by oil and gas industry group Energy in Depth as factually inaccurate; in response, a detailed rebuttal of the claims of inaccuracy has been posted on Gasland's website. The Colorado Oil and Gas Conservation Commission, a state agency, based on its own investigations, pointed out scientific errors made in the film and on the Gasland website concerning supposed cases of water wells contaminated by hydraulic fracturing.

A 2011 report by the Massachusetts Institute of Technology addressed groundwater contamination, noting "There has been concern that these fractures can also penetrate shallow freshwater zones and contaminate them with fracturing fluid, but there is no evidence that this is occurring. There is, however, evidence of natural gas migration into freshwater zones in some areas, most likely as a result of substandard well completion practices by a few operators. There are additional environmental challenges in the area of water management, particularly the effective disposal of fracture fluids". This study encourages the use of industry best practices to prevent such events from recurring.

In 2011, investigators from the Colorado School of Public Health performed a study in Garfield regarding potential adverse health effects, and concluded that residents near gas wells might suffer chemical exposures, accidents from industry operations, and psychological impacts such as depression, anxiety and stress. This study (the only one of its kind to date) was never published, owing to disagreements between community members and the drilling company over the study's methods.

Appalachian Basin

Jackson County, West Virginia, 1987

As early as 1987, an E.P.A. report was published that indicated fracture fluid invasion into James Parson's water well in Jackson County, West Virginia. The well, drilled by Kaiser Exploration and Mining Company, was found to have induced fractures that created a pathway to allow fracture fluid to contaminate the groundwater from which Mr. Parson's well was producing. The oil and gas industry and the E.P.A. disagreed regarding the accuracy and thoroughness of this report. In 2006 5 to 7 million cubic feet of methane were released from a blown gas well in Clark, Wyoming. Directed by Congress, the U.S. EPA announced in March 2010 that it will examine claims of water pollution related to hydraulic fracturing.

Dimock, Pennsylvania

In 2009 13 water wells in Dimock, Pennsylvania were contaminated with methane (one blew up). Arsenic, barium, DEHP, glycol compounds, manganese, phenol, and sodium were also found in unacceptable levels in the wells. As a result, Cabot Oil & Gas was required to financially compensate residents and provide alternative sources of water until mitigation systems were installed in affected wells. The company continues to deny, however, that any "of the issues in Dimock have anything to do with hydraulic fracturing". The devices needed to prevent such water contamination cost as little as $600. On December 2, 2011, EPA sent an email to several Dimock residents indicating that their well water presented no immediate health threat. On January 19, 2012, the EPA reversed its position, and asked that the agency's hazardous site cleanup division take immediate action to protect public health and safety. EPA began follow up testing and sampling local water supplies in Dimock in early 2012. In May 2012 EPA reported that their most recent "set of sampling did not show levels of contaminants that would give EPA reason to take further action." Methane was found only in one well. Cabot has held that the methane was preexisting, but state regulators have cited chemical fingerprinting as proof that it was from Cabot's hydraulic fracturing activities. Both Duke University and University of Rochester are conducting studies of the age of the well water to confirm the sources of the various contaminants. EPA plans to re-sample four wells where previous data by the company and the state showed levels of contaminants.

Duke University study, Pennsylvania and New York, 2011

In 2011 a Duke University study published in Proceedings of the National Academy of Sciences examined methane in groundwater in Pennsylvania and New York states overlying the Marcellus Shale and the Utica Shale. It determined that groundwater tended to contain much higher concentrations of methane near fracking wells, with potential explosion hazard; the methane's isotopic signatures and other geochemical indicators were consistent with it originating in the fracked deep shale formations, rather than any other source.

Duke University study, Pennsylvania, 2013

On June 24, 2013, researchers from Duke University reported detecting methane in drinking water in Pennsylvania and claim "serious contamination from bubbly methane is 'much more' prevalent in some water wells within 1 kilometer of gas drilling sites". The researchers noted that methane levels were "an average of six times" higher and ethane levels were "23 times higher" in the water wells "closer to drilling sites, compared with those farther away."

Pavillion, Wyoming

Complaints about water quality from residents near a gas field in Pavillion, Wyoming prompted an EPA groundwater investigation. The EPA reported detections of methane and other chemicals such as phthalates in private water wells. An EPA draft report dated December 8, 2011 suggested that the ground water in the Pavillion, Wyoming, aquifer contains "compounds likely associated with gas production practices, including hydraulic fracturing". The EPA discovered traces of methane and foaming agents in several water wells near a gas rig. During the investigation Luke Chavez (EPA investigator), commented that the contaminants could have come from cleaning products or oil and gas production, but said that in either case, their presence suggested problematic practices. Samples of water taken from EPA's deep monitoring wells in the aquifer were found to contain gasoline, diesel fuel, BTEX (benzene, toluene, ethylbenzene, xylene), naphthalenes, isopropanol, and synthetic chemicals (e.g., glycols and alcohols) used in gas production and hydraulic fracturing fluid, and high methane levels. Benzene concentrations in the samples were well above Safe Drinking Water Act standards. The EPA report stated concerns about the movement of contaminants within the aquifer and the future safety of drinking water in the context of the area's complex geology. EPA's sampling of Pavilion area drinking water wells found chemicals consistent with those reported in previous EPA reports, including but not limited to methane and other petroleum hydrocarbons, indicating migration of contaminants from areas of gas production. The report also said that contaminants in wells near pits indicated that (frack) pits are a source of shallow ground water contamination. It also said, "Detections of organic chemicals are more numerous and exhibit higher concentrations in the deeper of the two monitoring wells … (which) along with trends in methane, potassium, chloride, and pH, suggest a deep source of contamination." Their observations of chemical reactions in the field led them to suggest that upward migration of chemicals from deep underground is the culprit. They also found that the reports companies filed detailing jobs listed chemicals as a class or as "proprietary," "rendering identification of constituents impossible." The draft report also stated: "Alter­na­tive expla­na­tions were care­fully con­sid­ered to explain indi­vid­ual sets of data. How­ever, when con­sid­ered together with other lines of evi­dence, the data indi­cates likely impact to ground water that can be explained by hydraulic fracturing." The EPA also said that the type of contamination found is "typically infeasible or too expensive to remediate or restore." Industry figures rejected the EPA's findings. In 2010 the U.S. Department of Health and Human Services' Agency for Toxic Substances and Disease Registry recommended that owners of tainted wells use alternate sources of water for drinking and cooking, and ventilation when showering. These recommendations were still in place as of December 2011. Encana is funding the alternate water supplies.

In 2012 the U.S. Geological Survey tested one of two EPA monitoring wells near Pavilion and found evidence of methane, ethane, diesel compounds and phenol, which the EPA had also identified in its 2011 report According to Duke University environmental scientist Rob Jackson, "The stray gas concentrations are very high, not only for methane but especially for ethane and propane. That combination suggests a fossil-fuel source for the gases." An industry advocate, however, says that the USGS found lower concentrations of the particular materials that suggested a fossil-fuel source than the EPA and that what was found could be naturally occurring because of circumstances unique to the area or the testing process. Not every instance of groundwater methane contamination is a result of hydraulic fracturing. Often, local water wells drill through many shale and coal layers that can naturally seep methane into the producing groundwater. This methane is often biogenic (created by organic material decomposition) in origin as opposed to thermogenic (created through "thermal decomposition of buried organic material"). Thermogenic methane is the methane most often sought after by oil & gas companies deep in the earth, whereas biogenic methane is found in shallower formations (where water wells are typically drilled). Through isotope analysis and other detection methods, it is often fairly easy to determine whether the methane is biogenic or thermogenic, and thus determine from where it is produced. The presence of thermogenic methane does not confirm the source of gas. The gas composition and isotopic finger print must be compared by experts with other known sources of gas to confirm a match.

In June 2013, the EPA announced that it was closing its investigation at Pavilion, and would not finish or seek peer review of its preliminary 2011 study. Further investigation will be done by the state of Wyoming.

In 2006 drilling fluids and methane were detected leaking from the ground near a gas well in Clark, Wyoming; 8 million cubic feet of methane were eventually released, and shallow groundwater was found to be contaminated.

Surface water

Hydraulic fracturing can affect surface water quality either through accidental spills at the wellsite, or by discharge of the flowback through existing water treatment works. Flowback is the portion of the injected frack liquid that flows back to the surface, along with oil, gas, and brine, when the well is produced. More than 90 percent of frac flowback and oil and gas produced water in the United States is disposed of into deep EPA-licensed Class II disposal wells, with the remaining less than 10 percent reused, evaporated, used for irrigation, or discharged to surface streams under an NPDES permit. Discharging oil and gas produced water to surface streams without an NPDES permit is a federal crime. A 2012 report by the General Accounting Office found that of nine oil and gas-producing states studied, underground injection disposal was by far the predominant method in all but Pennsylvania. Very little oil and gas produced water in Pennsylvania was disposed of by underground injection because there were only six active waste disposal wells in Pennsylvania.

In Pennsylvania, oil and gas produced water had for many years been accepted by licensed water treatment works for treatment and discharge, but the volume expanded greatly with the proliferation of Marcellus Shale wells after 2000. Such discharges through water treatment works must comply with the federal Clean Water Act and the terms of their NPDES permits, but the EPA noted that most water treatment works are not set up to treat oilfield wastes. In 2010 the Pennsylvania Department of Environmental Protection (DEP) limited surface water discharges from new treatment plants to 250 mg/l chloride; the chloride limitation was designed to also limit other contaminants such as radium. Existing water treatment plants were "grandfathered," and still allowed higher discharge concentrations, but in April 2011, the DEP gave unconventional oil and gas operators 30 days to stop sending wastewater to the grandfathered treatment plants.

2011 EPA study of water pollution by hydraulic fracturing. Directed by Congress, the U.S. EPA announced in March 2010 that it would examine claims of water pollution related to hydraulic fracturing. The 2012 EPA Hydraulic Fracturing Draft Plan was narrowed to exclude studying the effects of flowback, also known as wastewater, and radioactive tracer isotopes, such as iodine-131 (found in Philadelphia's drinking water), used in hydraulic fracturing. Christopher Portier, director of the US CDC's National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry, argued that, in addition to the EPA's plans to investigate the impact of fracking on drinking water, additional studies should be carried out to determine whether wastewater from the wells can harm people or animals and vegetables they eat. A group of US doctors called for a moratorium on fracking in populated areas until such studies had been done.

Radioactivity

See also: Radionuclides associated with hydraulic fracturing

Radioactivity associated with hydraulically fractured wells comes from two sources: naturally occurring radioactive material and radioactive tracers introduced into the wells. Liquid waste from oil and gas wells is usually disposed of deep underground in Class II injection wells, but in Pennsylvania, much of the wastewater from hydraulic fracturing operations is processed by public sewage treatment plants. Many sewage plants say that they are incapable of removing the radioactive components of this waste, which is often released into major rivers. Industry officials, though, claim that these levels are diluted enough that public health is not compromised.

Naturally occurring radioactive materials

The New York Times has reported radiation in hydraulic fracturing wastewater released into rivers in Pennsylvania. It collected data from more than 200 natural gas wells in Pennsylvania and has posted a map entitled Toxic Contamination from Natural Gas Wells in Pennsylvania. The Times stated "never-reported studies" by the United States Environmental Protection Agency and a "confidential study by the drilling industry" concluded that radioactivity in drilling waste cannot be fully diluted in rivers and other waterways. Despite this, as of early 2011 federal and state regulators did not require sewage treatment plants that accept drilling waste (which is mostly water) to test for radioactivity. In Pennsylvania, where the drilling boom began in 2008, most drinking-water intake plants downstream from those sewage treatment plants have not tested for radioactivity since before 2006. The New York Times reporting has been criticized and one science writer has taken issue with one instance of the newspaper's presentation and explanation of its calculations regarding dilution, charging that a lack of context made the article's analysis uninformative.

According to a Times report in February 2011, wastewater at 116 of 179 deep gas wells in Pennsylvania "contained high levels of radiation," but its effect on public drinking water supplies is unknown because water suppliers are required to conduct tests of radiation "only sporadically". The New York Post stated that the Pennsylvania Department of Environmental Protection reported that all samples it took from seven rivers in November and December 2010 "showed levels at or below the normal naturally occurring background levels of radioactivity", and "below the federal drinking water standard for Radium 226 and 228." However the samples taken by the state at at least one river, (the Monongahela, a source of drinking water for parts of Pittsburgh), were taken upstream from the sewage treatment plants accepting drilling waste water.

The New York Times noted that in 2011 the Pennsylvania Department of Environmental Protection (DEP) only made a "request — not a regulation" of gas companies to stop sending their flowback and waste water to public water treatment facilities. However, the DEP gave oil and gas operators 30 days to voluntarily comply, and they all did. Former Pennsylvania DEP Secretary John Hanger, who served under Gov. Ed Rendell, affirmed that municipal drinking water throughout the state is safe. "Every single drop that is coming out of the tap in Pennsylvania today meets the safe drinking water standard," Hanger said, but added that the environmentalists were accurate in stating that Pennsylvania's water treatment plants were not equipped to treat hydraulic fracturing water. Current Pennsylvania DEP Secretary Michael Krancer serving under Gov. Tom Corbett has said it is "total fiction" that untreated wastewater is being discharged into the state's waterways, though it has been observed that Corbett received over a million dollars in gas industry contributions, more than all his competitors combined, during his election campaign. The New York Times reported that regulations are lax in Pennsylvania. The oil and gas industry is generally left to police itself in the case of accidents. Unannounced inspections are not made by regulators: the companies report their own spills, and create their own remediation plans. A recent review of the state-approved plans found them to appear to be in violation of the law. Treatment plants are still not equipped to remove radioactive material and are not required to test for it. Despite this, in 2009 the Ridgway Borough’s public sewage treatment plant, in Elk County, PA, facility was sent wastewater containing radium and other types of radiation at at 275-780 times the drinking-water standard. The water being released from the plant was not tested for radiation levels. Part of the problem is that growth in waste produced by the industry has outpaced regulators and state resources. It should be noted that "safe drinking water standards" have not yet been set for many of the substances known to be in hydrofracturing fluids or their radioactivity levels, and their levels are not included in public drinking water quality reports.

The EPA has asked the Pennsylvania Department of Environmental Protection to require community water systems in certain locations, and centralized wastewater treatment facilities to conduct testing for radionuclides. Safe drinking water standards have not yet been established to account for possible substances or radioactivity levels known to be in hydraulic fracturing waste water, and although water suppliers are required to inform citizens of radon and other radionuclides levels in their water, this doesn't always happen.

Radioactive tracers

Radioactive tracer isotopes are sometimes injected with hydraulic fracturing fluid to determine the injection profile and location of created fractures. Sand containing gamma-emitting tracer isotopes is used to trace and measure fractures. A 1995 study found that radioactive tracers were used in over 15% of stimulated oil and gas wells. In the United States, injection of radionuclides are licensed and regulated by the Nuclear Regulatory Commission (NRC). According to the NRC, some of the most commonly used tracers include antimony-124, bromine-82, iodine-125, iodine-131, iridium-192, and scandium-46. A 2003 publication by the International Atomic Energy Agency confirms the frequent use of most of the tracers above, and says that manganese-56, sodium-24, technetium-99m, silver-110m, argon-41, and xenon-133 are also used extensively because they are easily identified and measured. The Water Research Foundation, Philadelphia Water Department, Water Environment Research Federation, and The American Water Works Association are currently investigating hydraulic fracturing as a potential source of the Iodine-131 found in Philadelphia's drinking water.

Pennsylvania

The quantity of wastewater and the unpreparedness of sewage plants to treat wastewater, is an issue in Pennsylvania. The Associated Press has reported that starting in 2011, the Pennsylvania Department of Environmental Protection strongly resisted providing the AP and other news organizations with information about complaints related to drilling. When waste brine is discharged to surface waters through conventional wastewater treatment plants, the bromide in the brine usually is not captured. Although not a health hazard by itself, in western Pennsylvania some downstream drinking water treatment plants using the surface water experienced increases in brominated trihalomethanes in 2009 and 2010. Trihalomethanes, undesirable byproducts of the chlorination process, form when the chlorine combines with dissolved organic matter in the source water, to form the trihalomethane chloroform. Bromine can substitute for some of the chlorine, forming brominated trihalomethanes. Because bromine has a higher atomic weight than chlorine, the partial conversion to brominated trihalomethanes increases the concentration by weight of total trihalomethanes.

Tests conducted in Pennsylvania in 2009 found "no evidence of elevated radiation levels" in waterways. At the time radiation concerns were not seen as a pressing issue. In 2011 The New York Times reported radium in wastewater from natural gas wells is released into Pennsylvania rivers, and compiled a map of these wells and their wastewater contamination levels, and stated that some EPA reports were never made public. The Times' reporting on the issue has come under some criticism. A 2012 study examining a number of hydraulic fracturing sites in Pennsylvania and Virginia by Pennsylvania State University, found that water that flows back from gas wells after hydraulic fracturing contains high levels of radium.

Before 2011, flowback in Pennsylvania was processed by public wastewater plants, which were not equipped to remove radioactive material and were not required to test for it. In 2010 the Pennsylvania Department of Environmental Protection (DEP) limited surface water discharges from new treatment plants to 250 mg/l chloride. This limitation was designed to also limit other contaminants such as radium. Existing water treatment plants were allowed higher discharge concentrations. In April 2011, the DEP asked unconventional gas operators to voluntarily stop sending wastewater to the grandfathered treatment plants. The PADEP reported that the operators had complied.

A 2012 study by researchers from the National Renewable Energy Laboratory, University of Colorado, and Colorado State University reported a reduction in the percentage of flowback treated through surface water discharge in Pennsylvania from 2008 through 2011. By late 2012, bromine concentrations had declined to previous levels in the Monongahela River, but remained high in the Allegheny.

A 2013 Duke University study sampled water downstream from a Pennsylvania wastewater treatment facility from 2010 through 2012 and found that creek sediment contained levels of radium 200 times background levels. The surface water had the same chemical signature as rocks in the Marcellus Shale formation along with high levels of chloride. The facility denied processing Marcellus waste after 2011. In May 2013 the facility signed another agreement to not accept or discharge Marcellus wastewater until it installed technology to remove the radioactive materials, metals and salts.

Seismicity

Hydraulic fracturing routinely produces microseismic events much too small to be detected except by sensitive instruments. These microseismic events are often used to map the horizontal and vertical extent of the fracturing. However, as of late 2012, there have been three instances of hydraulic fracturing, through induced seismicity, triggering quakes large enough to be felt by people: one each in the United States, Canada, and England.

A 2012 US Geological Survey study reported that a "remarkable" increase in the rate of M ≥ 3 earthquakes in the US midcontinent "is currently in progress", having started in 2001 and culminating in a 6-fold increase over 20th century levels in 2011. The overall increase was tied to earthquake increases in a few specific areas: the Raton Basin of southern Colorado (site of coalbed methane activity), and gas-producing areas in central and southern Oklahoma, and central Arkansas. While analysis suggested that the increase is "almost certainly man-made", the United States Geological Survey (USGS) noted: "USGS's studies suggest that the actual hydraulic fracturing process is only very rarely the direct cause of felt earthquakes." The increased earthquakes were said to be most likely caused by increased injection of gas-well wastewater into disposal wells. The injection of waste water from oil and gas operations, including from hydraulic fracturing, into saltwater disposal wells may cause bigger low-magnitude tremors, being registered up to 3.3 (M_w).

Induced seismicity from hydraulic fracturing

The USGS has reported earthquakes induced by hydraulic fracturing and by disposal of hydraulic fracturing flowback into waste disposal wells in several locations. Bill Ellsworth, a geoscientist with the U.S. Geological Survey, has said, however: "We don't see any connection between fracking and earthquakes of any concern to society." The National Research Council (part of the National Academy of Sciences) has also observed that hydraulic fracturing, when used in shale gas recovery, does not pose a serious risk of causing earthquakes that can be felt. In 2013, Researchers from Columbia University and the University of Oklahoma demonstrated that in the midwestern United States, some areas with increased human-induced seismicity are susceptible to additional earthquakes triggered by the seismic waves from remote earthquakes. They recommended increased seismic monitoring near fluid injection sites to determine which areas are vulnerable to remote triggering and when injection activity should be ceased.

Induced seismicity from water disposal wells

Earthquakes large enough to be felt by people have also been linked to some deep disposal wells that receive hydraulic fracturing flowback and produced water from hydraulically fractured wells. Flowback and brine from oil and gas wells are injected into US EPA-regulated class II disposal wells. According to the EPA, approximately 144,000 such class II disposal wells in the US receive more than 2 billion US gallons (7.6 Gl) of wastewater each day. To date, the strongest earthquakes triggered by underground waste injection were three quakes close to Richter magnitude 5 recorded in 1967 near a Colorado disposal well which received non-oilfield waste.

According to the USGS only a small fraction of roughly 40,000 waste fluid disposal wells for oil and gas operations in the United States have induced earthquakes that are large enough to be of concern to the public. Although the magnitudes of these quakes has been small, the USGS says that there is no guarantee that larger quakes will not occur. In addition, the frequency of the quakes has been increasing. In 2009, there were 50 earthquakes greater than magnitude 3.0 in the area spanning Alabama and Montana, and there were 87 quakes in 2010. In 2011 there were 134 earthquakes in the same area, a sixfold increase over 20th century levels. There are also concerns that quakes may damage underground gas, oil, and water lines and wells that were not designed to withstand earthquakes.

The 2011 Oklahoma earthquake, the largest earthquake in Oklahoma history (most sources describe it as magnitude 5.7, although the US Geological Survey lists it as 5.6) has been linked by some researchers to decades-long injection of brine. However, the Oklahoma Geological Survey believes that the quake was most likely due to natural causes, and was not triggered by waste injection.

Class II disposal wells receiving brine from Fayetteville Shale gas wells in Central Arkansas triggered hundreds of shallow earthquakes, the largest of which was magnitude 4.7, and caused damage. In April 2011, the Arkansas Oil and Gas Commission halted injection at two of the main disposal wells, and the earthquakes abated.

Several earthquakes in 2011, including a 4.0 magnitude tremor on New Year's Eve that hit Youngstown, Ohio, are likely linked to a disposal of hydraulic fracturing wastewater, according to seismologists at Columbia University. By order of the Ohio Department of Natural Resources, the well had stopped injecting on December 30, 2011. The following day, after the 4.0 quake, Ohio governor John Kasich ordered an indefinite halt to injection in three additional deep disposal wells in the vicinity. The Department of Natural Resources proposed a number of tightened rules to its Class II injection regulations. The Department noted that there were 177 operational Class II disposal wells in the state, and that the Youngstown well was the first to produce recorded earthquakes since Ohio's Underground Injection Control program began in 1983.

Since 2008, more than 50 earthquakes, up to a magnitude of 3.5, have occurred in the area of north Texas home to numerous Barnett Shale gas wells, an area that previously had no earthquakes. No injuries or serious damage from the earthquakes has been reported. A study of quakes near the Dallas-Fort Worth Airport 2008-2009, concluded that the quakes were triggered by disposal wells receiving brine from gas wells.

A two-year study 2009-2011 by University of Texas researchers concluded that a number of earthquakes from Richter magnitude 1.5 to 2.5 in the Barnett Shale area of north Texas were linked to oilfield waste disposal into Class II injection wells. No quakes were linked to hydraulic fracturing itself. Researchers noted that there are more than 50,000 Class II disposal wells in Texas receiving oilfield waste, yet only a few dozen are suspected of triggering earthquakes.

Other monitoring resources

Andrew Revkin identified two web-based resources available to help monitor fracking and its impacts in affected regions.

• In Pennsylvania, Fracktrack.org was developed "to organize masses of data on drilling permits, violations and other activities related to the natural gas drilling rush in that state". Jamie Serra, developer of the site, set out to provide "a suite of tools to help landowners and citizens of the commonwealth understand what’s happening around them".
• SkyTruth, drawing on "data that are voluntarily submitted by gas companies to the FracFocus chemical disclosure registry", has created a fracking-chemical data base.

Revkin also provided an EPA video to encourage local infrared video monitoring of methane leakage from gas operations.

See also

• Environmental issues in the United States
• Exemptions for hydraulic fracturing under United States federal law
• Pollution in the United States

Further reading

• Natural gas wells leakier than believed: Measurements at Colorado site show methane release higher than previous estimates 24 March 2012, differences between NOAA and United States Environmental Protection Agency estimates

External links

• FracTracker.org Maps, data, and articles from news, government, industry, and academic sources.