Environmental impact of fracking: Difference between revisions

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Environmental impact of hydraulic fracturing includes the potential contamination of ground water, risks to air quality, noise pollution, the potential migration of gases and hydraulic fracturing chemicals to the surface, the potential mishandling of waste, and the health effects of these, like cancer.^[1]^[2] Many cases of suspected groundwater contamination have been documented.^[3]^[4] The EPA has noted that "Ground water contamination with constituents such as those found at Pavillion is typically infeasible or too expensive to remediate or restore (GAO 1989)."^[5] A review of a University of Texas Austin study led by Charles G. Groat, reported no direct evidence that fracking's actual injection phase resulted in contamination of ground water.^[6]^[7]^[8] In the study "fracking" was defined as referring only to the injection of fluid under pressure and excluded the impact of equipment failure, spills, the nature of the fluids, preparations prior to injection, and events following the injection, such as disposal of wastewater.^[6] The review suggests that problems occur due to leaks in its fluid or waste storage apparatus which it does not consider part of fracking. The review also says that gaps remain in understanding fracking.^[7]^[8] Because hydraulic fracturing was invented in the United States,^[9] and therefore has a longer history there, most of the studies of the environmental impact have been conducted there.

Scientific debate

It has been reported that the industry and governmental pressure have made it difficult to conduct and report the results of comprehensive studies of hydraulic fracturing. EPA investigations into the oil and gas industry's environmental impact have been narrowed in scope and/or reportedly had negative findings removed due to this pressure.^[10]^[11]^[12] A 2012 Cornell University report noted that it was difficult to assess health impact because of legislation, proprietary secrecy, and non-disclosure agreements that allow hydraulic fracturing companies to keep the proprietary chemicals used in the fluid secret. Pre-drilling tests and other assessments have also found that water supplies—especially private water wells—often suffer from high levels of naturally occurring contaminants, as the US Geological Survey concluded in August 2011.^[13] Nonetheless, these particular Cornell researchers recommended requiring disclosure of all hydraulic fracturing fluids, that nondisclosure agreements not be allowed when public health is at risk, testing animals (and their products) raised near hydraulic fracturing sites against animals 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. Despite the lack of conclusive data, however, the researchers also wrote that "a ban on shale gas drilling is essential for the protection of public health."^[14] The co-chair of the Chemicals Technical Options Committee for the United Nations Environment Program, Dr. Ian Rae, recently criticized the Cornell researchers' conclusions, saying, "It certainly does not qualify as a scientific paper but is, rather, an advocacy piece that does not involve deep analysis of the data gathered to support its case." Rae added that the Cornell researchers "cannot be regarded as experts" in this particular field. Others have pointed out that the study does still raise important questions, and it echoes similar concerns of some landowners and environmental groups.^[15] In addition, after court cases concerning contamination from hydraulic fracturing are settled, the documents are sealed. While the American Petroleum Institute denies that this practice has hidden problems with gas drilling, others believe it has and could lead to unnecessary risks to public safety and health.^[16]

The New York Times reported that the results of the 2004 EPA study were censored due to strong industry influence and political pressure (regulatory capture).^[10] An early draft of the study discussed the possibility of dangerous levels of fracking fluid contamination and mentioned "possible evidence" of aquifer contamination. The final report concluded simply that fracking "poses little or no threat to drinking water".^[10] The study's scope was narrowed so that it only focused on the injection of fracking fluids, ignoring other aspects of the process such as disposal of fluids and environmental concerns such as water quality, fish kills, and acid burns. The study was concluded before public complaints of contamination started emerging.^[17]^: 780 The study's conclusion that the injection of fracking fluids into coalbed methane wells posed a minimal threat to underground drinking water sources^[18] may have influenced the 2005 Congressional decision that hydraulic fracturing should continue to be regulated by the states and not under the federal Safe Drinking Water Act.

The 2012 EPA Hydraulic Fracturing Draft Plan was also narrowed. It does not include studying the effects of iodine-131 (found in Philadelphia's drinking water)^[19]^[20]^[21] or other radioactive tracer isotopes used in hydraulic fracturing.^[22]^[23]^[24] Nor does the draft plan include evaluating the impact of wastewater. 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.^[25] A group of US doctors called for a moratorium on fracking in populated areas until such studies had been done.^[26]^[27]

Proponents of hydraulic fracturing have claimed 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,^[28]^[29] although the study did note that other steps in the drilling process—excepting the actual injection of the fluid—have been sources of environmental contamination.^[6] Conflicting interpretations of this study are based on disagreement between industry and the environmental community about what "hydraulic fracturing" actually is: Industry notes that hydraulic fracturing is a specific process, which takes place after the well has been drilled and the drilling equipment has left the pad; the environmental community, however, uses hydraulic fracturing, or "fracking," to describe the entire production phase. The radioactivity of the injected fluid itself was not assessed in the University of Texas study.^[6]

As of 2009, state regulators from across the country stated that they had seen no evidence of hydraulic fracturing contaminating water in their respective jurisdictions.^[30] In May 2011 EPA Administrator Lisa P. Jackson testified in a Senate Hearing Committee stating that she is not aware of any proof where the fracking process itself has contaminated water.^[31] EPA and other reports released since that time, however, have identified hydraulic fracturing as the likely source of water contamination.^[3]^[5]^[16]^[32]^[33]^[34]

Air emissions

The main hydraulic-fracturing-related air emissions are methane emissions from the wells during fracturing and emissions from hydraulic fracturing 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. Some studies have found that hydraulic fracturing has higher emissions due to gas released during completing wells as some gas returns to the surface, together with the fracturing fluids. Depending on their treatment, the well-to-burner emissions are 3.5%–12% higher than for conventional gas.^[35] A debate has arisen particularly around a study by professor Robert W. Howarth finding shale gas significantly worse for global warming than oil or coal.^[36] Other researchers have criticized Howarth's analysis,^[37]^[38] including Cathles et al., whose estimates were substantially lower."^[39] The U.S. EPA has estimated the methane leakage rate to be about 2.4% – well below Howarth’s estimate. The American Gas Association, and industry trade group, calculated a 1.2% leakage rate ^[40] based on the EPA's latest greenhouse gas inventory. A 2012 industry funded 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 so-called “conventional well” natural gas, and less than half the emissions of coal.^[41] Another industry affiliated study estimated the amount of methane leakage from shale gas development and production could be as low as less than 1% of total gas production, or as high as several percent.^[42] In April 2013 the EPA lowered its estimate of how much methane gas is released to the atmosphere during the hydraulic fracturing process by 20%. Howarth objected, pointing out that other federal climate scientists from the National Oceanic and Atmospheric Administration (NOAA) have published recent studies documenting massive methane leaks from natural gas operations in Colorado and other Western states. He suggested that EPA needs an outside independent review of their process. The EPA said it is seeking more data, but stands by its new estimates. "^[43] An additional concern is that oil obtained through hydraulic fracturing contains chemicals used in hydraulic fracturing, which may increase the rate at which rail tank cars and pipelines corrode, potentially releasing their load and its gases.^[44]^[45]

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.^[41]

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%.^[46] Using data from the Environmental Protection Agency's most recent Greenhouse Gas Inventory^[47] yields a methane leakage rate of about 1.4%, down from 2.3% from the EPA's previous Inventory.^[48]

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,^[42] 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.

In 2008, measured ambient concentrations near drilling sites in Sublette County, Wyoming were frequently above the National Ambient Air Quality Standards (NAAQS) of 75ppb and have been recorded as high as 125 ppb.^[49] A 2011 study for the city of Fort Worth, Texas, examining air quality around natural gas sites "did not reveal any significant health threats."^[50]^[51] In DISH, Texas, elevated levels of disulfides, benzene, xylenes and naphthalene have been detected in the air, emitted from the compressor stations.^[52] People living near shale gas drilling sites often "complain of headaches, diarrhea, nosebleeds, dizziness, blackouts, muscle spasms, and other problems."^[53] Cause-and-effect relationships have not been established in all cases.^[53] 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.^[2] 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.^[54]

Also transportation of necessary water volume for hydraulic fracturing, if done by trucks, can cause high volumes of air emissions, especially particulate matter emissions.^[55] There are also reports of health problems around compressors stations^[52] or drilling sites,^[53] although a causal relationship was not established for the limited number of wells studied^[53] and another Texas government analysis found no evidence of effects.^[56]

In DISH, Texas, elevated levels of disulphides, benzene, xylenes and naphthalene have been detected in the air.^[52] According to an article in 'Environmental Health Perspectives,' people living near shale gas drilling sites often "complain of headaches, diarrhea, nosebleeds, dizziness, blackouts, muscle spasms, and other problems."^[53] Cause-and-effect relationships have not been established.^[53]

Water consumption

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.^[57]^[58] An average well requires 3 to 8 million US gallons (11,000 to 30,000 m³) of water over its lifetime.^[59]^[58]^[60]^[61] According to the Oxford Institute for Energy Studies, greater volumes of fracturing fluids are required in Europe, where the shale depths average 1.5 times greater than in the U.S.^[62]

Concern has been raised over the increasing quantities of water for hydraulic fracturing. Use of water for hydraulic fracturing can divert water from stream flow, water supplies for municipalities and industries such as power generation, as well as recreation and aquatic life.^[63] The large volumes of water required for most common hydraulic fracturing methods have raised concerns for arid regions, such as Karoo in South Africa,^[9] and in Pennsylvania,^[64]^[65] and in drought-prone Texas, and Colorado in North America.^[66] It may also require water overland piping from distant sources.^[60]

Some producers have developed hydraulic fracturing techniques that could reduce the need for water.^[67] Using carbon dioxide, liquid propane or other gases instead of water have been proposed to reduce water consumption.^[68] After it is used, the propane returns to its gaseous state and can be collected and reused. In addition to water savings, gas fracturing reportedly produces less damage to rock formations that can impede production.^[67] Recycled flowback water can be reused in hydraulic fracturing.^[35] It lowers the total amount of water used and reduces the need to dispose of wastewater after use. The technique is relatively expensive, however, since the water must be treated before each reuse and it can shorten the life of some types of equipment.^[69]

New data shows that water saved by using natural gas combined cycle plants instead of coal steam turbine plants saves 25–50 times more water than the amount of water needed to extract the gas using hydraulic fracturing.^[70]

Groundwater contamination

Flowback

As the fracturing fluid flows back through the well, it consists of spent fluids and may contain dissolved constituents such as minerals and brine waters. It may account for about 30–70% of the original fracture fluid volume. In addition, natural formation waters may flow to the well and need treatment. approaches to managing these fluids, commonly known as produced water, include underground injection, municipal and commercial wastewater treatment and discharge, self‐contained systems at well sites or fields, or recycling to fracture future wells.^[71] However, the quantity of waste water needing treatment and the improper configuration of sewage plants have become an issue in some regions of the United States. Much of the wastewater from hydraulic fracturing operations is processed by public sewage treatment plants, which are not equipped to remove radioactive material and are not required to test for it.^[72]^[73]

Hydraulic fracturing can concentrate uranium, radium, radon and thorium in flowback.^[74] Estimates of the amount of injected fluid returning to the surface vary. Estimates of the fluid that returns to the surface with the gas range from 15-20%^[75] to 30–70%. the fluid is often mixed with formation water.^[76]^[71] Additional fluid may return to the surface through abandoned wells or other pathways.^[77] After the flowback is recovered, formation water, usually brine, may continue to flow to the surface, requiring treatment or disposal. Approaches to managing these fluids, commonly known as flowback, produced water, or wastewater, include underground injection, municipal waste water treatment plants, industrial wastewater treatment, self-contained systems at well sites or fields, and recycling to fracture future wells.^[41]^[71]^[78]^[79] One Duke University study reported that "Marcellus [Shale] wells produce significantly less wastewater per unit gas recovered (~35%) compared to conventional natural gas wells.”^[80] In Colorado the volume of wastewater discharged to surface streams increased from 2008 to 2011.^[41]

In 2013 the vacuum multi-effect membrane distillation system was introduced to treat flowback. It is a hybrid system that uses both distillation and reverse osmosis to process the water. The water is repeatedly distilled through a membrane onto a collector. The system is operated in a partial vacuum to reduce the water's boiling point to 50–80 °C (122–176 °F). The purified result is appropriate for use in irrigation and may be made potable according to the company offering the service. The residual is highly concentrated brine, which can be reinjected or recycled using other technology.^[81]

Surface spills are another concern surrounding the hydro-fracking process. In a 2013 at the American Industrial Hygiene Conference and Expo in Montreal, Quebec experts met to discuss this topic. It was found that 77% of surface spills that affected groundwater were recorded in Weld County, where 18,000 wells were active. Also on average about seven barrels of hydraulic fracturing liquid are spilled during each incident. Most spills occur because of equipment failure or engineering misjudgments.^[82] The management practices behind hydraulic fracturing are crucial to the success of this process and also prove to be a large environmental concern.^[83]^[84]

Volatile chemicals held in waste water evaporation ponds can to evaporate into the atmosphere, or overflow. In one of the cases described by a 2012 Cornell University study (conducted in Colorado, Louisiana, New York, Ohio, Pennsylvania and Texas) impounded wastewater was released into a field and pond, killing at least 70 animals.^[14] The runoff can also end up in groundwater systems. Groundwater may become contaminated by trucks carrying fracking chemicals and wastewater if they are involved in accidents on the way to fracking sites or disposal destinations.^[6]

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.^[85]

Methane

Groundwater methane contamination is also a concern as it has adverse effect on water quality and in extreme cases may lead to potential explosion.^[73]^[86] In 2006, over 7 million cubic feet (200,000 m³) of methane were released from a blown gas well in Clark, Wyoming and shallow groundwater was found to be contaminated.^[87] A scientific study reported in the PNAS investigated concerns over fracking and well water. The study found high correlations of drilling activity and methane pollution of the drinking water.^[88] Methane contamination is not always caused by hydraulic fracturing. Drilling for ordinary drinking water wells can also cause methane release. Most recent studies make use of tests that can distinguish between the deep thermogenic methane released during gas/oil drilling, and the shallower biogenic methane that can be released during water-well drilling. While both forms of methane result from decomposition, thermogenic methane results from geothermal assistance deeper underground.^[89]^[90]

According to the 2011 study of the MIT Energy Initiative, "there is evidence of natural gas (methane) migration into freshwater zones in some areas, most likely as a result of substandard well completion practices i.e. poor quality cementing job or bad casing, by a few operators."^[85] 2011 studies by the Colorado School of Public Health and Duke University also pointed to methane contamination stemming from hydraulic fracturing or its surrounding process.^[86]^[90] A study by Cabot Oil and Gas examined the Duke study using a larger sample size, found that methane concentrations were related to topography, with the highest readings found in low-lying areas, rather than related to distance from gas production areas. Using a more precise isotopic analysis, they showed that the methane found in the water wells came from both the Marcellus Shale (Middle Devonian) where hydraulic fracturing occurred, and from the shallower Upper Devonian formations.^[89] A 2013 Duke study suggested that both defective cement seals in the upper part of wells and faulty steel linings within deeper layers may be allowing methane and injected fluid to seep into surface waters.^[91] Abandoned gas and oil wells also provide conduits to the surface.^[77] A recent Duke University study found methane concentrations six times higher and ethane concentrations were 23 times higher at residences within a kilometer of a shale gas well. Propane was also detected in 10 homes within a kilometer of drilling. The researchers reported that the methane, ethane and propane data, and new evidence from hydrocarbon and helium content, all suggested that drilling has affected the drinking water. They noted that the ethane and propane data were notable because there was no biological source of ethane and propane in the region and Marcellus gas is higher in both than are Upper Devonian gases.^[92]

The Colorado Oil & Gas Conservation Commission has found some wells containing thermogenic methane due to oil and gas development upon investigating complaints from residents.^[90] A review published in February 2012 found no direct evidence that fracking's actual injection phase resulted in contamination of ground water, and suggests that reported problems occur due to leaks in its fluid or waste storage apparatus; the review says that methane in water wells in some areas probably comes from natural resources.^[7]^[8]

Injected fluid

Template:Globalize/US There are concerns about possible contamination by hydraulic fracturing fluid both as it is injected under high pressure into the ground and as it returns to the surface.^[93]^[91] To mitigate the effect of hydraulic fracturing on groundwater, the well and ideally the shale formation itself should remain hydraulically isolated from other geological formations, especially freshwater aquifers.^[35]

While some of the chemicals used in hydraulic fracturing are common and generally harmless, some are known carcinogens.^[1] Out of 2,500 hydraulic fracturing products, more than 650 contained known or possible human carcinogens regulated under the Safe Drinking Water Act or listed as hazardous air pollutants".^[1] Between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their Occupational Safety and Health Administration (OSHA) required material safety data sheet (MSDS). The MSDS is a list of chemical components in the products of chemical manufacturers, and according to OSHA, a manufacturer may withhold information designated as "proprietary" from this sheet. Most companies participating in the investigation were unable to name the ingredients of the products they use, leading the committee to surmise these "companies are injecting fluids containing unknown chemicals about which they may have limited understanding of the potential risks posed to human health and the environment".^[1] Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it more difficult to prove that hydraulic fracturing is contaminating the environment with these substances.^[94]

Another 2011 study identified 632 chemicals used in natural gas operations. Only 353 of these are well-described in the scientific literature. The study indicated possible long-term health effects that might not appear immediately. The study recommended full disclosure of all products used, along with extensive air and water monitoring near natural gas operations; it also recommended that hydraulic fracturing's exemption from regulation under the US Safe Drinking Water Act be rescinded.^[95] Industry group Energy In Depth, a research arm of the Independent Petroleum Association of America, contends that fracking "was never granted an 'exemption' from it... How can something earn an exemption from a law that never covered or even conceived of it in the first place?”^[96]

Governments are responding to questions about the contents of hydraulic fracturing fluid by requiring disclosure via government agencies and public web site. The Irish regulatory regime requires full disclosure of all additives to Ireland's Environmental Protection Agency (Ireland). The European Union also requires such disclosure.^[97] In the US, the Ground Water Protection Council launched FracFocus.org, an online voluntary disclosure database for hydraulic fracturing fluids funded by oil and gas trade groups and the U.S. Department of Energy. The site has been met with some skepticism relating to proprietary information that is not included.^[98]^[99] Some states have mandated fluid disclosure and incorporated FracFocus as the tool for disclosure.^[100]^[101] Also in the US, The FracTracker Alliance provides oil and gas-related data storage, analyses, and online and customized maps related to hydraulic fracturing on FracTracker.org.^[102]^[103]

Radioactivity

There are concerns about the levels of radioactivity in wastewater from hydraulic fracturing and its potential impact on public health. Recycling this wastewater has been proposed as a partial solution, but this approach has limitations.^[104]

The New York Times has reported radiation in hydraulic fracturing wastewater released into rivers in Pennsylvania.^[73] 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. Sand containing gamma-emitting tracer isotopes is used to trace and measure fractures.^[22] 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.^[105] Individuals exposed to high enough levels of radiation may experience symptoms of acute radiation syndrome, including fatigue, leukopenia, fever, diarrhea, vomiting, nose bleeds, dizziness, disorientation, low blood pressure, seizures, and tremors.^[106] 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.^[93] 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.^[73] The New York Times reporting has been criticized by aggrieved parties,^[107] but one venerable science writer has taken issue with one instance of the newspaper's presentation and explanation of its calculations regarding dilution,^[104] charging that a lack of context made the article's analysis uninformative.^[108]

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".^[109] 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."^[110] 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.^[111]

In Pennsylvania, much of this wastewater from hydraulic fracturing operations is processed by public sewage treatment plants. However, 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.^[73] This is a major concern as it provides the possibility for radioactive waste to enter into public water supplies.

The New York Times has implicated the DEP in industry-friendly inactivity, requesting rather than requiring them to handle their own flowback waste rather than sending it to public water treatment facilities.^[112] However, former Pennsylvania DEP Secretary John Hanger, who served under Gov. Ed Rendell (D), has affirmed that municipal drinking water throughout the state is safe, but added that the environmentalists were accurate in stating that Pennsylvania's water treatment plants were not equipped to treat hydraulic fracturing water.^[113] Current Pennsylvania DEP Secretary Michael Krancer serving under Gov. Tom Corbett (R) has denied that untreated wastewater is being discharged into the state's waterways.^[114] It has been observed that Corbett received over a million dollars in gas industry contributions,^[115] more than all his competitors combined, during his election campaign.^[116] The New York Times reported that regulations are lax in Pennsylvania.^[73] 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.^[73] A recent review of the state-approved plans found them to appear to be in violation of the law.^[73] Treatment plants are still not equipped to remove radioactive material and are not required to test for it.^[73] 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.^[73] Part of the problem is that growth in waste produced by the industry has outpaced regulators and state resources.^[73] 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,^[73] and their levels are not included in public drinking water quality reports.^[117]

Seismology

Hydraulic fracturing causes induced seismicity called microseismic events or microearthquakes. These microseismic events are often used to map the horizontal and vertical extent of the fracturing.^[118] The magnitude of these events is usually too small to be detected at the surface, although the biggest micro-earthquakes may have the magnitude of about -1.6 (M_w). 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.^[119]^[120]^[121] The injection of waste water from gas operations, including from hydraulic fracturing, into saltwater disposal wells may cause bigger low-magnitude tremors, being registered up to 3.3 (M_w).^[122]

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.^[123] While analysis suggested that the increase is "almost certainly man-made", the 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.^[124] 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).^[122]

Induced seismicity from hydraulic fracturing

The United States Geological Survey (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.”^[125] 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.^[126] 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.^[119]^[127]

A British Columbia Oil and Gas Commission investigation concluded that a series of 38 earthquakes (magnitudes ranging from 2.2 to 3.8 on the Richter scale) occurring in the Horn River Basin area between 2009 and 2011 were caused by fluid injection during hydraulic fracturing in proximity to pre-existing faults. The tremors were small enough that only one of them was reported felt by people; there were no reports of injury or property damage.^[128]

A report in the UK concluded that hydraulic fracturing was the likely cause of two small tremors (magnitudes 2.3 and 1.4 on the Richter scale) that occurred during hydraulic fracturing of shale.^[129]^[130]^[131]

Induced seismicity from water disposal wells

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.^[120] Although the magnitudes of these quakes has been small, the USGS says that there is no guarantee that larger quakes will not occur.^[132] 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.^[133] There are also concerns that quakes may damage underground gas, oil, and water lines and wells that were not designed to withstand earthquakes.^[132]^[134]

Several earthquakes in 2011, including a 4.0 magnitude quake on New Year's Eve that hit Youngstown, Ohio, are likely linked to a disposal of hydraulic fracturing wastewater,^[119] according to seismologists at Columbia University.^[135] A similar series of small earthquakes occurred in 2012 in Texas. Earthquakes are not common occurrences in either area. Disposal and injection wells are regulated under the Safe Drinking Water Act and UIC laws.^[136]

Health risks

Hydraulic fracturing fluids have the potential to enter water sources, and air currents through chemical spills, through evaporation of wastewater, and through errors in the drilling process.^[73] Trace amounts of these chemicals may affect the health of those working on or living near the wells. In Colorado, the U.S. Agency for Toxic Substances and Disease Registry sampled 14 sites, and found high levels of carcinogens such as benzene, tetrachloroethene, and 1-4 dichlorobenzene.^[137] In July 2011, the EPA released new emissions guidelinees stating that current standards could lead to an unacceptably high risk of cancers for those living near drilling operations.^[137] Pediatric Environmental Health Specialty Units(PEHSU) also found chemical contamination of drinking water near fracking operations in New York and Pennsylvania that involved detectable and harmful levels of benzene toluene, ethyl benzene, xylene, ethylene glycol, glutaldehyde, and other biocides such as hydrochloric acid, and hydrogen treated light petroleum distillates.^[138] Human exposure to these chemicals can result in cancer, adverse effects of the reproductive, neurological, and endocrine systems.^[138] Exposure to specialized chemical solutions patented by energy service companies, such as Zetaflow, used by Weatherford International, may result in kidney and liver damage, irritated lung tissue, decreased blood pressure, dizziness, and vomiting according to their Meterial Safety Data Sheet.^[139]

PEHSU has linked higher vulnerability in children to health risks associated with chemical exposure to fracking fluids.^[138] This increased risk is due to a higher ratio of consumption pound for pound versus adults' rate of consumption, along with the inability to metabolize certain toxants that the body is able to metabolize as an adult.^[138] The same kind of vulnerability is also exhibited in development of the fetus during pregnancy, and health risks may involve neural tube defects, decreased birth perameters, and childhood leukemia.^[138]

The growing of oil and natural gas drilling employing fracking technology is steady around different regions of the United States, but the maintenance of wastewater gathered after the drilling process containing fracking fluids is lagging behind.^[140] In Pennsylvania, the Department of Environmental Protection reported that the resources to properly regulate wastewater-handling facilities were unavailable, inspecting facilities every 20 years rather than every 2 years as called for by regulation.^[140]

Richard A. Muller, a Principal of the China Shale Fund,^[141] argues that the benefits from shale gas made available by fracking, by displacing harmful air pollution from coal, far outweigh their combined environmental costs. In a 2013 report for the Centre for Policy Studies, Muller writes that air pollution, mostly from coal burning, kills over three million people each year, primarily in the developing world. The report does not reference any studies on air pollution associated with gas produced through hydraulic fracturing.^[142]

Anti-fracking movement

An anti-fracking movement has emerged both internationally with involvement of international environmental organizations and nation states such as France and locally in affected areas such as Balcombe in Sussex where the Balcombe drilling protest was in progress during summer 2013.^[143]

References

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^ ^a ^b Mall, Amy (19 December 2011). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". Switchboard: NRDC Staff Blog. Natural Resources Defense Council. Retrieved 23 February 2012.
^ Lustgarten, Abrahm (November 2008). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". ProPublica. Retrieved 20 March 2012.
^ ^a ^b DiGiulio, Dominic C.; Wilkin, Richard T.; Miller, Carlyle; Oberley, Gregory (2011). Investigation of Ground Water Contamination near Pavillion, Wyoming. Draft (PDF) (Report). EPA. Retrieved 23 March 2012. {{cite report}}: Unknown parameter |month= ignored (help)
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^ ^a ^b ^c "Fracking Acquitted of Contaminating Groundwater". Science. 335: 898. 24 February 2012.
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^ ^a ^b Urbina, Ian (30 December 2011). "Hunt for Gas Hits Fragile Soil, and South Africans Fear Risks". The New York Times. Retrieved 23 February 2012. Covering much of the roughly 800 miles between Johannesburg and Cape Town, this arid expanse – its name [Karoo] means "thirsty land" – sees less rain in some parts than the Mojave Desert.
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^ "Fracking gas leak estimates lowered". 3 News. NZ. April 29, 2013.
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^ Hanna, Bill; Smith, Jack Z. (July 15, 2011). "Study: No 'significant health threats' from natural gas sites in Fort Worth". Fort Worth Star-Telegram. Retrieved 2012-05-24.
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^ ^a ^b Abdalla, Charles W.; Drohan, Joy R. (2010). Water Withdrawals for Development of Marcellus Shale Gas in Pennsylvania. Introduction to Pennsylvania’s Water Resources (PDF) (Report). The Pennsylvania State University. Retrieved 16 September 2012. Hydrofracturing a horizontal Marcellus well may use 4 to 8 million gallons of water, typically within about 1 week. However, based on experiences in other major U.S. shale gas fields, some Marcellus wells may need to be hydrofractured several times over their productive life (typically five to twenty years or more)
^ Ground Water Protection Council; ALL Consulting (2009). Modern Shale Gas Development in the United States: A Primer (PDF) (Report). DOE Office of Fossil Energy and National Energy Technology Laboratory. pp. 56–66. DE-FG26-04NT15455. Retrieved 24 February 2012. {{cite report}}: Unknown parameter |month= ignored (help)
^ ^a ^b Arthur, J. Daniel; Uretsky, Mike; Wilson, Preston (May 5–6, 2010). Water Resources and Use for Hydraulic Fracturing in the Marcellus Shale Region (PDF). Meeting of the American Institute of Professional Geologists. Pittsburgh: ALL Consulting. p. 3. Retrieved 2012-05-09.
^ Cothren, Jackson. Modeling the Effects of Non-Riparian Surface Water Diversions on Flow Conditions in the Little Red Watershed (PDF) (Report). U. S. Geological Survey, Arkansas Water Science Center Arkansas Water Resources Center, American Water Resources Association, Arkansas State Section Fayetteville Shale Symposium 2012. p. 12. Retrieved 16 September 2012. ...each well requires between 3 and 7 million gallons of water for hydraulic fracturing and the number of wells is expected to grow in the future
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^ Hopey, Don (1 March 2011). "Gas drillers recycling more water, using fewer chemicals". Pittsburgh Post-Gazette. Retrieved 27 March 2013.
^ Litvak, Anya (21 August 2012). "Marcellus flowback recycling reaches 90 percent in SWPA". Pittsburgh Business Times. Retrieved 27 March 2013.
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^ ^a ^b ^c Kim, Won-Young 'Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio', Journal of Geophysical Research-Solid Earth
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^ Ellsworth, W. L.; Hickman, S.H.; McGarr, A.; Michael, A. J.; Rubinstein, J. L. Are seismicity rate changes in the midcontinent natural or manmade?. Seismological Society of America 2012 meeting. San Diego, California: Seismological Society of America. Retrieved 2014-02-23.
^ US Geological Survey, Man-made earthquakes, accessed 22 Sept. 2013.
^ Soraghan, Mike (13 December 2013). "Disconnects in public discourse around 'fracking' cloud earthquake issue". E&E News. Retrieved 27 March 2013.
^ "Induced Seismicity Potential in Energy Technologies". National Academies Press. Retrieved 27 March 2013. The process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events.
^ van der Elst1, Nicholas J.; Savage, Heather M.; Keranen, Katie M; Abers, Geoffrey A. (12 July 2013). "Enhanced Remote Earthquake Triggering at Fluid-Injection Sites in the Midwestern United States". Science. 341 (6142). ACS Publications: 164–167. doi:10.1126/science.1238948.{{cite journal}}: CS1 maint: numeric names: authors list (link)
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^ Soraghan, Mike (29 March 2012). "'Remarkable' spate of man-made quakes linked to drilling, USGS team says". EnergyWire. E&E. Retrieved 2012-11-09.
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^ "Ohio Quakes Probably Triggered by Waste Disposal Well, Say Seismologists" (Press release). Lamont–Doherty Earth Observatory. 6 January 2012. Retrieved 22 February 2012.
^ "EPA Underground Injection Control Program". Retrieved 2012-04-13.
^ ^a ^b Abrahm Lustgarten and Nicholas Kusnetz (2011-09-16). "Science Lags as Health Problems Emerge Near Gas Fields". Propublica. Retrieved 2013-05-06.
^ ^a ^b ^c ^d ^e PEHSU (August 2011). PEHSU Information Concerning Effects on Children of Natural Gas Extraction and Hydraulic Fracturing (Report). Propublica. Retrieved 2013-05-06.
^ "A Toxic Spew?". 19 August 2008. Retrieved 6 May 2013.
^ ^a ^b "With Natural Gas Drilling Boom, Pennsylvania Faces an Onslaught of Wastewater". Propublica. 3 October 2009. Retrieved 7 August 2013. {{cite news}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
^ http://www.chinashalefund.com/ China Shale Fund
^ Why Every Serious Environmentalist Should Favour Fracking, 2013 report by Richard A. Muller and Elizabeth A. Muller of Berkeley Earth
^ Jan Goodey (Undated, but July, 2013). "The UK's anti fracking movement is growing". The Ecologist. Retrieved July 29, 2013. {{cite news}}: Check date values in: |date= (help)

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[house1-1] Chemicals Used in Hydraulic Fracturing (PDF) (Report). Committee on Energy and Commerce U.S. House of Representatives. April 18, 2011.

[HeatOnGas-2] Brown, Valerie J. (February 2007). "Industry Issues: Putting the Heat on Gas". Environmental Health Perspectives. 115 (2). US National Institute of Environmental Health Sciences: A76. doi:10.1289/ehp.115-a76. PMC 1817691. PMID 17384744. Retrieved 2012-05-01.

[AutoZV-21-3] Mall, Amy (19 December 2011). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". Switchboard: NRDC Staff Blog. Natural Resources Defense Council. Retrieved 23 February 2012.

[AutoZV-22-4] Lustgarten, Abrahm (November 2008). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". ProPublica. Retrieved 20 March 2012.

[EPA_Pavillion_Dec2011-5] DiGiulio, Dominic C.; Wilkin, Richard T.; Miller, Carlyle; Oberley, Gregory (2011). Investigation of Ground Water Contamination near Pavillion, Wyoming. Draft (PDF) (Report). EPA. Retrieved 23 March 2012. {{cite report}}: Unknown parameter |month= ignored (help)

[UT_Study-6] Energy Institute (2012). Fact-Based Regulation for Environmental Protection in Shale Gas Development (PDF) (Report). University of Texas at Austin. p. ?. Retrieved 29 February 2012. {{cite report}}: Unknown parameter |month= ignored (help)

[FrackMix1-7] "Fracking Acquitted of Contaminating Groundwater". Science. 335: 898. 24 February 2012.

[FrackMix2-8] Erik Stokstad (16 February 2012). "Mixed Verdict on Fracking". Science.

[NYTUrbina30Dec2011-9] Urbina, Ian (30 December 2011). "Hunt for Gas Hits Fragile Soil, and South Africans Fear Risks". The New York Times. Retrieved 23 February 2012. Covering much of the roughly 800 miles between Johannesburg and Cape Town, this arid expanse – its name [Karoo] means "thirsty land" – sees less rain in some parts than the Mojave Desert.

[Urbina_03Mar2011-10] Urbina, Ian (3 March 2011). "Pressure Limits Efforts to Police Drilling for Gas". The New York Times. Retrieved 23 February 2012. More than a quarter-century of efforts by some lawmakers and regulators to force the federal government to police the industry better have been thwarted, as E.P.A. studies have been repeatedly narrowed in scope and important findings have been removed

[hfstudy-11] "EPA's Study of Hydraulic Fracturing and Its Potential Impact on Drinking Water Resources". EPA. Retrieved 24 February 2010.

[NYT_Docs-12] "Natural Gas Documents". The New York Times. 27 February 2011. Retrieved 5 May 2012. The Times reviewed more than 30,000 pages of documents obtained through open records requests of state and federal agencies and by visiting various regional offices that oversee drilling in Pennsylvania. Some of the documents were leaked by state or federal officials.

[sir2011-5059-13] Joseph D. Ayotte; et al. (August 2011). "Trace Elements and Radon in Groundwater Across the United States, 1992-2003". U.S. Geological Survey. Retrieved 25 May 2012. {{cite web}}: Explicit use of et al. in: |author= (help)

[Cornellvet03092012-14] Ramanuja, Krishna (7 Martch 2012). "Study suggests hydrofracking is killing farm animals, pets". Cornell Chronicle. Cornell University. Retrieved 9 March 2012. {{cite news}}: Check date values in: |date= (help)

[theconversation110112-15] Helen Westerman (11 January 2012). "Gas drilling research highlights risk to animals, but more thorough work needed". The Conversation. Retrieved 25 May 2012.

[Urbina_03Aug2011-16] Urbina, Ian (3 August 2011). "A Tainted Water Well, and Concern There May be More". The New York Times. Retrieved 22 February 2012.

[DammelNotes-17] Dammel, Joseph A. (2011). "Notes From Underground: Hydraulic Fracturing in the Marcellus Shale" (PDF). Minnesota Journal of Law, Science and Technology. 12 (2). University of Minnesota Law School: 773–810. Retrieved 24 February 2012.

[EPA_2004-18] Evaluation of Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane Reservoirs; National Study Final Report (PDF) (Report). EPA. June 2004. Retrieved 23 February 2011.

[EPA_radiation-19] Jeff McMahon (10 April 2011). "EPA: New Radiation Highs in Little Rock Milk, Philadelphia Drinking Water". Forbes. Retrieved 22 February 2012.

[epa.gov-20] "Japanese Nuclear Emergency: Radiation Monitoring". EPA. 30 June 2011. Retrieved 23 February 2012.

[Carbon_County-21] Bauers, Sandy (21 July 2011). "Cancer patients' urine suspected in Wissahickon iodine-131 levels". Philadelphia inquirer, Carbon County Groundwater Guardians. Retrieved 25 February 2012.

[No5635712-22] [1] Scott III, George L. (03-June-1997) US Patent No. 5635712: Method for monitoring the hydraulic fracturing of a subterranean formation. US Patent Publications.

[US4415805-23] [2] Fertl; Walter H. (15-Nov-1983) US Patent No. US4415805: Method and apparatus for evaluating multiple stage fracturing or earth formations surrounding a borehole. US Patent Publications.

[US5441110-24] [3] Scott III, George L. (15-Aug-1995) US Patent No. US5441110: System and method for monitoring fracture growth during hydraulic fracture treatment. US Patent Publications.

[BW_04Jan2012-25] Alex Wayne (4 January 2012). "Health Effects of Fracking Need Study, Says CDC Scientist". Bloomberg Businessweek. Retrieved 29 February 2012.

[BW_19.01.2012-26] David Wethe (19 January 2012). "Like Fracking? You'll Love 'Super Fracking'". Businessweek. Retrieved 22 January 2012.

[Bloomberg_11.01.2012-27] Mark Drajem (11 January 2012). "Fracking Political Support Unshaken by Doctors' Call for Ban". Bloomberg. Retrieved 19 January 2012.

[fuelfix-28] Vaughan, Vicki (16 February 2012). "Fracturing 'has no direct' link to water pollution, UT study finds". Retrieved 3 March 2012.

[vancouversun-29] Munro, Margaret (17 February 2012). "Fracking does not contaminate groundwater: study released in Vancouver". Vancouver Sun. Retrieved 3 March 2012.

[minerals-30] "Hydraulic Fracturing – 15 Statements from Regulatory Officials" (PDF). New York Department of Environmental Conservation. Retrieved 25 May 2012.

[jackson-31] "Pathways To Energy Independence: Hydraulic Fracturing And Other New Technologies". U.S. Senate. May 6, 2011.

[Phillips_2011-32] Susan Phillips (8 December 2011). "EPA Blames Fracking for Wyoming Groundwater Contamination". StateImpact Pennsylvania. WITF, WHYY & NPR. Retrieved 6 February 2012. {{cite web}}: soft hyphen character in |work= at position 17 (help)

[EPA_Dimock_letter_2012-33] Fetzer, Richard M. (19 January 2012). Action Memorandum - Request for funding for a Removal Action at the Dimock Residential Groundwater Site (PDF) (Report). Retrieved 27 May 2012.

[bswk_09272012-34] Mark Drajem (27 September 2012). "Diesel in Water Near Fracking Confirms EPA Tests Wyoming Disputes". Bloomberg News. Retrieved 28 September 2012.

[WEO2011full-35] IEA (2011). World Energy Outlook 2011. OECD. pp. 91, 164. ISBN 978 92 64 12413 4.

[howarth-36] Howarth, Robert W.; Santoro, Renee; Ingraffea, Anthony (13 March 2011). "Methane and the greenhouse-gas footprint of natural gas from shale formations" (PDF). Climatic Change. 106 (4). Springer: 679–690. doi:10.1007/s10584-011-0061-5. Retrieved 2012-05-07.

[Cathles-37] Cathles, Lawrence M.; Brown, Larry; Taam, Milton; Hunter, Andrew (2011). "A commentary on "The greenhouse-gas footprint of natural gas in shale formations"". Climatic Change. doi:10.1007/s10584-011-0333-0. Retrieved 7 August 2013. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

[ipsnewsShale-38] Stephen Leahy (24 January 2012). "Shale Gas a Bridge to More Global Warming". IPS. Retrieved 4 February 2012.

[Howarth3-39] Howarth, Robert W.; Santoro, Renee; Ingraffea, Anthony (1 February 2012). "Venting and leaking of methane from shale gas development: Response to Cathles et al" (PDF). Climatic Change. Springer. doi:10.1007/s10584-012-0401-0. Retrieved 4 February 2012.

[McCurdyDave-40] "The Importance of Accurate Data". True Blue Natural Gas. Retrieved 27 March 2013.

[LoganJeffrey-41] Logan, Jeffrey (2012). Natural Gas and the Transformation of the U.S. Energy Sector: Electricity (PDF) (Report). Joint Institute for Strategic Energy Analysis. Retrieved 27 March 2013.

[Allen-42] Allen, David T.; Torres, Vincent N.; Thomas, James; Sullivan, David W.; Harrison, Matthew; Hendler, Al; Herndon, Scott C.; Kolb, Charles E.; Fraser, Matthew P.; Hill, A. Daniel; Lamb, Brian K.; Miskimins, Jennifer; Sawyer, Robert F.; Seinfeld, John H. (16 September 2013). "Measurements of methane emissions at natural gas production sites in the United States" (PDF). Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1304880110. Retrieved 2013-10-02.

[3news-43] "Fracking gas leak estimates lowered". 3 News. NZ. April 29, 2013.

[Bloomberg08132013-44] Jim Efstathiou Jr. and Angela Greiling Keane (13 August 2013). "North Dakota Oil Boom Seen Adding Costs for Rail Safety". Bloomberg. Retrieved 19 January 2012.

[reuters10112013-45] Gebrekidan, Selam (11 October 2013). "Corrosion may have led to North Dakota pipeline leak: regulator". Reuters. Retrieved 31 December 2013.

[Trembath-46] Trembath, Alex; Luke, Max; Shellenberger, Michael; Nordhaus, Ted (June 2013). "Coal Killer: How Natural Gas Fuels the Clean Energy Revolution" (PDF). Breakthrough institute. p. 22. Retrieved 2 October 2013.

[47] "U.S. Greenhouse Gas Inventory Report". United States Environmental Protection Agency. Retrieved 2013-10-02.

[48] "5 Reasons Why It's Still Important To Reduce Fugitive Methane Emissions". World Resources Institute. Retrieved 2013-10-02.

[tribOzoneWyoming-49] "Ozone mitigation efforts continue in Sublette County, Wyoming". Wyoming's Online News Source. March 2011.

[fortworthtexas-50] Eastern Research Group, Sage Environmental Consulting (July 13, 2011). City of Fort Worth: Natural Gas Air Quality Study (PDF) (Report). City of Fort Worth. Retrieved 2012-05-07.

[starFortWorthNoThreats-51] Hanna, Bill; Smith, Jack Z. (July 15, 2011). "Study: No 'significant health threats' from natural gas sites in Fort Worth". Fort Worth Star-Telegram. Retrieved 2012-05-24.

[DISH_TX_SciAm-52] Biello, David (30 March 2010). "Natural gas cracked out of shale deposits may mean the U.S. has a stable supply for a century – but at what cost to the environment and human health?". Scientific American. Retrieved 23 March 2012.

[DISH_TX_EHP-53] ^ ^a ^b ^c ^d ^e ^f Schmidt, Charles (1 August 2011). "Blind Rush? Shale Gas Boom Proceeds Amid Human Health Questions". Environmental Health Perspectives. 119: a348–a353. doi:10.1289/ehp.119-a348. Retrieved 23 March 2012.

[atthefrontAirImpacts-54] "Study shows air emissions near fracking sites may have serious health impacts". @theForefront. Colorado School of Public Health. 19 March 2012. Retrieved 25 April 2012.

[BMP-55] Fernandez, John Michael; Gunter, Matthew. "Hydraulic Fracturing: Environmentally Friendly Practices" (PDF). Houston Advanced Research Center. Retrieved 2012-12-29. {{cite journal}}: Cite journal requires |journal= (help)

[TexasDSHS-56] "DISH, TExas Exposure Investigation" (PDF). Texas DSHS. Retrieved 27 March 2013.

[CRO_2009-57] Andrews, Anthony; et al. (30 October 2009). Unconventional Gas Shales: Development, Technology, and Policy Issues (PDF) (Report). Congressional Research Service. pp. 7, 23. Retrieved 22 February 2012. {{cite report}}: Explicit use of et al. in: |author= (help)

[Penn_State_Water-58] Abdalla, Charles W.; Drohan, Joy R. (2010). Water Withdrawals for Development of Marcellus Shale Gas in Pennsylvania. Introduction to Pennsylvania’s Water Resources (PDF) (Report). The Pennsylvania State University. Retrieved 16 September 2012. Hydrofracturing a horizontal Marcellus well may use 4 to 8 million gallons of water, typically within about 1 week. However, based on experiences in other major U.S. shale gas fields, some Marcellus wells may need to be hydrofractured several times over their productive life (typically five to twenty years or more)

[DOE_primer-59] Ground Water Protection Council; ALL Consulting (2009). Modern Shale Gas Development in the United States: A Primer (PDF) (Report). DOE Office of Fossil Energy and National Energy Technology Laboratory. pp. 56–66. DE-FG26-04NT15455. Retrieved 24 February 2012. {{cite report}}: Unknown parameter |month= ignored (help)

[ALL-Marcellus-60] Arthur, J. Daniel; Uretsky, Mike; Wilson, Preston (May 5–6, 2010). Water Resources and Use for Hydraulic Fracturing in the Marcellus Shale Region (PDF). Meeting of the American Institute of Professional Geologists. Pittsburgh: ALL Consulting. p. 3. Retrieved 2012-05-09.

[US_Geological_Survey-61] Cothren, Jackson. Modeling the Effects of Non-Riparian Surface Water Diversions on Flow Conditions in the Little Red Watershed (PDF) (Report). U. S. Geological Survey, Arkansas Water Science Center Arkansas Water Resources Center, American Water Resources Association, Arkansas State Section Fayetteville Shale Symposium 2012. p. 12. Retrieved 16 September 2012. ...each well requires between 3 and 7 million gallons of water for hydraulic fracturing and the number of wells is expected to grow in the future

[shale_Europe-62] Faucon, Benoît (17 September 2012). "Shale-Gas Boom Hits Eastern Europe". WSJ.com. Retrieved 17 September 2012.

[Grist81513-63] John Upton (August 15, 2013). "Fracking company wants to build new pipeline — for water". Grist. Retrieved August 16, 2013.

[Jefferson_letter_2008-64] Janco, David F. (3 January 2008). PADEP Determination Letter No. 352 Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request. Order: Atlas Miller 42 and 43 gas wells; Aug 2007 investigation; supplied temporary buffalo for two springs, ordered to permanently replace supplies (PDF) (Report). Scranton Times-Tribune. Retrieved 27 December 2013.

[Snow_Shoe_letter_2007-65] Janco, David F. (1 February 2007). PADEP Determination Letter No. 970. Diminution of Snow Shoe Borough Authority Water Well No. 2; primary water source for about 1,000 homes and businesses in and around the borough; contested by Range Resources. Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request (PDF) (Report). Scranton Times-Tribune. Retrieved 27 December 2013.

[water_battles-66] Staff (16 June 2013). "Fracking fuels water battles". Politico. Associated Press. Retrieved 26 June 2013.

[window.state.tx.us-67] Texas Water Report: Going Deeper for the Solution Texas Comptroller of Public Accounts. Retrieved 2/11/14.

[68] "Skipping the Water in Fracking."

[WSJ11202012-69] Sider, Alison; Lefebvre, Ben (20 November 2012). "Drillers Begin Reusing 'Frack Water.' Energy Firms Explore Recycling Options for an Industry That Consumes Water on Pace With Chicago". The Wall Street Journal. Retrieved 20 October 2013.

[70] Drought and the water–energy nexus in Texas Environmental Research Letters. Retrieved 2/11/14.

[Arthur2-71] Arthur, J. Daniel; Langhus, Bruce; Alleman, David (2008). An overview of modern shale gas development in the United States (PDF) (Report). ALL Consulting. p. 21. Retrieved 2012-05-07.

[Neshaminy_2009-72] David Caruso (2011-01-03). "44,000 Barrels of Tainted Water Dumped Into Neshaminy Creek. We're the only state allowing tainted water into our rivers". NBC Philadelphia. Associated Press. Retrieved 2012-04-28.

[Urbina_26Feb2011-73] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m Urbina, Ian (26 February 2011). "Regulation Lax as Gas Wells' Tainted Water Hits Rivers". The New York Times. Retrieved 22 February 2012.

[Weinhold_2012-74] Weinhold, Bob (19 September 2012). "Unknown Quantity: Regulating Radionuclides in Tap Water". Environmental Health Perspectives. NIEHS, NIH. Retrieved 11 February 2012. Examples of human activities that may lead to radionuclide exposure include mining, milling, and processing of radioactive substances; wastewater releases from the hydraulic fracturing of oil and natural gas wells... Mining and hydraulic fracturing, or "fracking", can concentrate levels of uranium (as well as radium, radon, and thorium) in wastewater... {{cite web}}: soft hyphen character in |quote= at position 117 (help)

[Ohio_DNR-75] Staff. Waste water (Flowback)from Hydraulic Fracturing (PDF) (Report). Ohio Department of Natural Resources. Retrieved 29 June 2013. Most of the water used in fracturing remains thousands of feet underground, however, about 15-20 percent returns to the surface through a steel-cased well bore and is temporarily stored in steel tanks or lined pits. The wastewater which returns to the surface after hydraulic fracturing is called flowback

[netldoe-76] Sandy McSurdy & Radisav Vidic (25 June 2013). Sustainable Management of Flowback Water during Hydraulic Fracturing of Marcellus Shale for Natural Gas Production (PDF) (Report). National Energy Technology Laboratory, US Department of Energy. Retrieved 29 June 2013.

[DetrowS-77] Detrow, Scott (9 October 2012). "Perilous Pathways: How Drilling Near An Abandoned Well Produced a Methane Geyser". StateImpact Pennsylvania. NPR. Retrieved 29 June 2013. As Shell was drilling and then hydraulically fracturing its nearby well, the activity displaced shallow pockets of natural gas — possibly some of the same pockets the Morris Run Coal company ran into in 1932. The gas disturbed by Shell's drilling moved underground until it found its way to the Butters well, and then shot up to the surface. Companies have been extracting oil and gas from Pennsylvania's subsurface since 1859, when Edwin Drake drilled the world's first commercial oil well. Over that 150-year timespan, as many as 300,000 wells have been drilled, an unknown number of them left behind as hidden holes in the ground. Nobody knows how many because most of those wells were drilled long before Pennsylvania required permits, record-keeping or any kind of regulation. It's rare for a modern drilling operation to intersect — the technical term is "communicate" — with an abandoned well. But incidents like Shell's Tioga County geyser are a reminder of the dangers these many unplotted holes in the ground can cause when Marcellus or Utica Shale wells are drilled nearby. And while state regulators are considering requiring energy companies to survey abandoned wells within a 1,000-foot radius of new drilling operations, the location of nearby wells is currently missing from the permitting process. That's the case in nearly every state where natural gas drillers are setting up hydraulic fracturing operations in regions with long drilling histories. Regulators don't require drillers to search for abandoned wells and plug them because, the thinking goes, this is something drillers are doing anyway. {{cite web}}: soft hyphen character in |work= at position 17 (help)

[HopeyDon-78] Hopey, Don (1 March 2011). "Gas drillers recycling more water, using fewer chemicals". Pittsburgh Post-Gazette. Retrieved 27 March 2013.

[LitvakAnya-79] Litvak, Anya (21 August 2012). "Marcellus flowback recycling reaches 90 percent in SWPA". Pittsburgh Business Times. Retrieved 27 March 2013.

[Lutz_2013-80] Lutz, Brian; Lewis, Aurana; Doyle, Martin (8 February 2013). "Generation, transport, and disposal of wastewater associated with Marcellus Shale gas development". Environmental Health Perspectives. 49 (2). Water Resources Research: 647–1197. doi:10.1002/wrcr.20096. Retrieved 2013-06-30.

[81] Economist (2013-11-30). "Monitor: Clean that up". The Economist. Retrieved 2013-12-15.

[82] (Surface Spills, 2013

[83] New Research of Surface Spills in Fracking Industry. (2013). Professional Safety, 58(9), 18.

[84] = savannahb022

[AutoZV-33-85] Moniz, Ernest J.; et al. (2011). The Future of Natural Gas: An Interdisciplinary MIT Study (PDF) (Report). Massachusetts Institute of Technology. Retrieved 1 June 2012. {{cite report}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)

[Duke_study_2010-86] Osborn, Stephen G.; Vengosh, Avner; Warner, Nathaniel R.; Jackson, Robert B. (2011-05-17). "Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 108 (20): 8172–8176. doi:10.1073/pnas.1100682108. Retrieved 2011-10-14.

[AutoZV-23-87] Blowout brings scrutiny to energy company

[88] "Duke Study finds Methane gas in well water near fracking sites" May 9, 2011 Philly Inquirer

[molofsky-89] Molofsky, L.J.; Connor, J.A.; Shahla, K.F.; Wylie, A.S.; Wagner, T. (December 5, 2011). "Methane in Pennsylvania Water Wells Unrelated to Marcellus Shale Fracturing". Oil and Gas Journal. 109 (49). Pennwell Corporation: 54–67.

[AutoZV-32-90] "Gasland Correction Document" (PDF). Colorado Oil & Gas Conservation Commission. Retrieved 7 August 2013. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

[EhrenburgR-91] Ehrenburg, Rachel (25 June 2013). "News in Brief: High methane in drinking water near fracking sites. Well construction and geology may both play a role". Science News. Retrieved 26 June 2013.

[PNAS06242013-92] Jackson, Robert B.; Vengosh, Avner; Darrah, Thomas; Warner, Nathaniel R. (24 June 2013). "Increased Stray Gas Abundance in a Subset of Drinking Water Wells Near Marcellus Shale Gas Extraction". Proceedings of the National Academy of Sciences. ACS Publications.

[NYT_Waste_Docs_26Feb2011-93] Staff (26 February 2011). "Drilling Down: Documents: Natural Gas's Toxic Waste". The New York Times. Retrieved 23 February 2012.

[AutoZV-16-94] Kris Fitz Patrick (November 17, 2011). "Ensuring Safe Drinking Water in the Age of Hydraulic Fracturing". The most fundamental recommendation is for states to rigorously test their ground water before and after hydraulic fracturing takes place. A major difficulty in proving or disproving contamination in previous cases has been the lack of a baseline sample for the water supply in question. The group also raises a federal policy issue, namely whether fracturing fluids should continue to be exempt from Safe Drinking Water Act regulations. This exemption was an informal one until 2005, when it was codified as part of the Energy Policy Act. A consequence of this exemption is that drilling companies are not required to disclose the chemicals that make up the fracturing fluids, making testing for these chemicals in ground water more difficult.

[AEHS_2011-95] Colborn, Theo; Kwiatkowski, Carol; Schultz, Kim; Bachran, Mary (2011). "Natural Gas Operations from a Public Health Perspective" (PDF). Human and Ecological Risk Assessment: An International Journal. 17 (5). Taylor & Francis: 1039–1056. doi:10.1080/10807039.2011.605662.

[EnergyInDepth01-96] "FAQ: Hydraulic Fracturing, SDWA, Fluids, and DeGette/Casey" (PDF). Energy In Depth. Retrieved 27 March 2013.

[EU-97] Dave Healy (July 2012). /sss/UniAberdeen_FrackingReport.pdf Hydraulic Fracturing or ‘Fracking’: A Short Summary of Current Knowledge and Potential Environmental Impacts A Small Scale Study for the Environmental Protection Agency (Ireland) under the Science, Technology, Research & Innovation for the Environment. (STRIVE) Programme 2007 (PDF) (Report). Environmental Protection Agency, Ireland. Retrieved 28 July 2013. {{cite report}}: Check |url= value (help)

[HassBenjamin-98] Hass, Benjamin (14 August 2012). "Fracking Hazards Obscured in Failure to Disclose Wells". Bloomberg News. Retrieved 27 March 2013.

[SoraghanMike02-99] Soraghan, Mike (13 December 2013). "White House official backs FracFocus as preferred disclosure method". E&E News. Retrieved 27 March 2013.

[WatsonMatt-100] "Colorado Sets The Bar on Hydraulic Fracturing Chemical Disclosure". Environmental Defense Fund. Retrieved 27 March 2013.

[MaykuthAndrew-101] Maykuth, Andrew (22 January 2012). "More states ordering disclosure of fracking chemicals". Philadelphia Inquirer. Retrieved 27 March 2013.

[PlainDealer04042013-102] Grant, Alison (4 April 2013). "FracTracker monitors shale development in Ohio". The Plain Dealer. Retrieved 28 July 2013.

[FracTracker-103] Staff. "FracTracker. Exploring data, sharing perspectives, and mapping impacts of the gas industry". FracTracker. Retrieved 28 July 2013.

[Urbina_01Mar2011-104] Urbina, Ian (1 March 2011). "Drilling Down: Wastewater Recycling No Cure-All in Gas Process". The New York Times. Retrieved 22 February 2012.

[WRF_report_2013-105] Timothy A. Bartrand and Jeffrey S. Rosen (October 2013). Potential Impacts and Significance of Elevated 131 I on Drinking Water Sources [Project #4486] ORDER NUMBER: 4486 (PDF) (Report). Water Research Foundation. Retrieved 11 November 2013.

[radiation_effects-106] Mayo clinic staff. "Radiation sickness". Mayo Clinic. Retrieved 31 March 2012.

[NYT_letters_05Mar2011-107] "Natural Gas Drilling, the Spotlight". The New York Times. 5 March 2011. Retrieved 24 February 2012.

[Petit_02Mar2011-108] Petit, Charles (2 March 2011). "Part II of the fracking water problems in PA and other Marcellus Shale country". Knight Science Journalism Tracker. MIT. Retrieved 6 May 2013.

[post230212-109] Don Hopey (5 March 2011). "Radiation-fracking link sparks swift reactions". Pittsburgh Post-Gazette. Retrieved 23 February 2012.

[110] Shocker: New York Times radioactive water report is false March 8, 2011 ι Abby Wisse Schachter. Report is from a Rupert Murdoch tabloid, The New York Post

[Urbina_07Mar2011-111] Urbina, Ian (7 March 2011). "E.P.A. Steps Up Scrutiny of Pollution in Pennsylvania Rivers". The New York Times. Retrieved 23 February 2012.

[griswold-112] Griswold, Eliza (17 November 2011). "The Fracturing of Pennsylvania". The New York Times Magazine. Retrieved 21 November 2011.

[cbs040111-113] "State Official: Pa. Water Meets Safe Drinking Standards". CBS Pittsburgh. January 4, 2011.

[prnewswire171111-114] "Pennsylvania DEP Secretary Defends States' Ability to Regulate Hydraulic Fracturing" (Press release). PR Newswire. November 17, 2011.

[gazette240211-115] Don Hopey (February 24, 2011). "Corbett repeals policy on gas drilling in parks". Pittsburgh Post-Gazette. Retrieved April 19, 2011.

[NYRB_08.03.2012-116] McKibben, Bill (8 March 2012). "Why Not Frack?". The New York Review of Books. 59 (4). Retrieved 21 February 2012.

[Phil_report_2010-117] Annual Drinking Water Quality Report, 2010 (PDF) (Report). Philadelphia Water Department. Spring 2011. Retrieved 7 February 2012.

[Oilfield_Review_2005/2006-118] Bennet, Les; et al. "The Source for Hydraulic Fracture Characterization" (PDF). Oilfield Review (Winter 2005/2006). Schlumberger: 42–57. Retrieved 2012-09-30. {{cite journal}}: Explicit use of et al. in: |author= (help)

[Kim-119] Kim, Won-Young 'Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio', Journal of Geophysical Research-Solid Earth

[AutoZV-36-120] "FAQs – Earthquakes, Faults, Plate Tectonics, Earth Structure: Can we cause earthquakes? Is there any way to prevent earthquakes?". USGS. 27 October 2009. Retrieved 22 February 2012.

[Reuters07122013-121] Begley, Sharon; McAllister, Edward (12 July 2013). "News in Science: Earthquakes may trigger fracking tremors". ABC Science. Reuters. Retrieved 17 December 2013.

[worldwatch-122] Zoback, Mark; Kitasei, Saya; Copithorne, Brad (2010). Addressing the Environmental Risks from Shale Gas Development (PDF) (Report). Worldwatch Institute. p. 9. Retrieved 2012-05-24. {{cite report}}: Unknown parameter |month= ignored (help)

[ellsworth-123] Ellsworth, W. L.; Hickman, S.H.; McGarr, A.; Michael, A. J.; Rubinstein, J. L. Are seismicity rate changes in the midcontinent natural or manmade?. Seismological Society of America 2012 meeting. San Diego, California: Seismological Society of America. Retrieved 2014-02-23.

[124] US Geological Survey, Man-made earthquakes, accessed 22 Sept. 2013.

[SoraghanMike03-125] Soraghan, Mike (13 December 2013). "Disconnects in public discourse around 'fracking' cloud earthquake issue". E&E News. Retrieved 27 March 2013.

[NationalResearchCouncil-126] "Induced Seismicity Potential in Energy Technologies". National Academies Press. Retrieved 27 March 2013. The process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events.

[Science2013-127] van der Elst1, Nicholas J.; Savage, Heather M.; Keranen, Katie M; Abers, Geoffrey A. (12 July 2013). "Enhanced Remote Earthquake Triggering at Fluid-Injection Sites in the Midwestern United States". Science. 341 (6142). ACS Publications: 164–167. doi:10.1126/science.1238948.{{cite journal}}: CS1 maint: numeric names: authors list (link)

[CBC_News_09062012-128] "Fracking causes minor earthquakes, B.C. regulator says". The Canadian Press. Canadian Broadcast Company — British Columbia. 6 September 2012. Retrieved 2012-10-28.

[BBC_08.06.2012-129] "Shale gas fracking: MPs call for safety inquiry after tremors". BBC News. 8 June 2011. Retrieved 22 February 2012.

[AutoZV-34-130] "Fracking tests near Blackpool 'likely cause' of tremors". BBC News. 2 November 2011. Retrieved 22 February 2012.

[AutoZV-35-131] Pater, C.J.; Baisch, S. (2 November 2011). Geomechanical Study of Bowland Shale Seismicity (PDF) (Report). Cuadrilla Resources. Retrieved 22 February 2012.

[Texas08072012-132] Rachel Maddow, Terrence Henry (7 August 2012). Rachel Maddow Show: Fracking waste messes with Texas (video). MSNBC. Event occurs at 9:24 - 10:35. {{cite AV media}}: |access-date= requires |url= (help)CS1 maint: date and year (link)

[EW03292012-133] Soraghan, Mike (29 March 2012). "'Remarkable' spate of man-made quakes linked to drilling, USGS team says". EnergyWire. E&E. Retrieved 2012-11-09.

[SITX08062012-134] Henry, Terrence (6 August 2012). "How Fracking Disposal Wells Are Causing Earthquakes in Dallas-Fort Worth". State Impact Texas. NPR. Retrieved 9 November 2012.

[AutoZV-37-135] "Ohio Quakes Probably Triggered by Waste Disposal Well, Say Seismologists" (Press release). Lamont–Doherty Earth Observatory. 6 January 2012. Retrieved 22 February 2012.

[Underground_Injection-136] "EPA Underground Injection Control Program". Retrieved 2012-04-13.

[ScienceLagsPropublica-137] Abrahm Lustgarten and Nicholas Kusnetz (2011-09-16). "Science Lags as Health Problems Emerge Near Gas Fields". Propublica. Retrieved 2013-05-06.

[PEHSUConcerningEffects-138] PEHSU (August 2011). PEHSU Information Concerning Effects on Children of Natural Gas Extraction and Hydraulic Fracturing (Report). Propublica. Retrieved 2013-05-06.

[AToxicSpew?-139] "A Toxic Spew?". 19 August 2008. Retrieved 6 May 2013.

[PennsylvaniaLackingResources-140] "With Natural Gas Drilling Boom, Pennsylvania Faces an Onslaught of Wastewater". Propublica. 3 October 2009. Retrieved 7 August 2013. {{cite news}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

[141] ttp://www.chinashalefund.com/ China Shale Fund

[142] Why Every Serious Environmentalist Should Favour Fracking, 2013 report by Richard A. Muller and Elizabeth A. Muller of Berkeley Earth

[Ecologist713-143] Jan Goodey (Undated, but July, 2013). "The UK's anti fracking movement is growing". The Ecologist. Retrieved July 29, 2013. {{cite news}}: Check date values in: |date= (help)

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 == Air emissions ==
-The main hydraulic-fracturing-related air emissions are [[methane]] emissions from the wells during fracturing and emissions from hydraulic fracturing 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. Some studies have found that hydraulic fracturing has higher emissions due to gas released during completing wells as some gas returns to the surface, together with the fracturing fluids. Depending on their treatment, the well-to-burner emissions are 3.5%–12% higher than for conventional gas.<ref name="WEO2011full" /> A debate has arisen particularly around a study by professor Robert W. Howarth finding shale gas significantly worse for global warming than oil or coal.<ref name="howarth" /> Other researchers have criticized Howarth's analysis,<ref name=Cathles /><ref name=ipsnewsShale /> including Cathles ''et al.,'' whose estimates were substantially lower."<ref name=Howarth3 /> The U.S. EPA has estimated the methane leakage rate to be about 2.4% – well below Howarth’s estimate.  The American Gas Association, and industry trade group, calculated a 1.2% leakage rate <ref name="McCurdyDave"/> based on the EPA's latest greenhouse gas inventory. A 2012 industry funded 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 so-called “conventional well” natural gas, and less than half the emissions of coal.<ref name="LoganJeffrey" /> Another industry affiliated study estimated the amount of methane leakage from shale gas development and production could be as low as less than 1% of total gas production, or as high as several percent.<ref name="Allen" /> In April 2013 the EPA lowered its estimate of how much methane gas is released to the atmosphere during the hydraulic fracturing process by 20%. Howarth objected, pointing out that other federal climate scientists from the [[National Oceanic and Atmospheric Administration]] (NOAA) have published recent studies documenting massive methane leaks from natural gas operations in Colorado and other Western states. He suggested that EPA needs an outside independent review of their process. The EPA said it is seeking more data, but stands by its new estimates. "<ref name="3news"/> An additional concern is that oil obtained through hydraulic fracturing contains chemicals used in hydraulic fracturing, which may increase the rate at which rail tank cars and pipelines corrode, potentially releasing their load and its gases.<ref name="Bloomberg08132013" /><ref name="reuters10112013" />
+The main hydraulic-fracturing-related air emissions are [[methane]] emissions from the wells during fracturing and emissions from hydraulic fracturing 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. Some studies have found that hydraulic fracturing has higher emissions due to gas released during completing wells as some gas returns to the surface, together with the fracturing fluids. Depending on their treatment, the well-to-burner emissions are 3.5%–12% higher than for conventional gas.<ref name="WEO2011full" /> A debate has arisen particularly around a study by professor Robert W. Howarth finding shale gas significantly worse for global warming than oil or coal.<ref name="howarth" /> Other researchers have criticized Howarth's analysis,<ref name=Cathles /><ref name=ipsnewsShale /> including Cathles ''et al.,'' whose estimates were substantially lower."<ref name=Howarth3 /> The U.S. EPA has estimated the methane leakage rate to be about 2.4% – well below Howarth’s estimate.  The American Gas Association, and industry trade group, calculated a 1.2% leakage rate <ref name="McCurdyDave">{{cite web |title=The Importance of Accurate Data |url=http://www.truebluenaturalgas.org/importance-accurate-data | publisher= True Blue Natural Gas |accessdate=27 March 2013}}</ref> based on the EPA's latest greenhouse gas inventory. A 2012 industry funded 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 so-called “conventional well” natural gas, and less than half the emissions of coal.<ref name="LoganJeffrey" /> Another industry affiliated study estimated the amount of methane leakage from shale gas development and production could be as low as less than 1% of total gas production, or as high as several percent.<ref name="Allen" /> In April 2013 the EPA lowered its estimate of how much methane gas is released to the atmosphere during the hydraulic fracturing process by 20%. Howarth objected, pointing out that other federal climate scientists from the [[National Oceanic and Atmospheric Administration]] (NOAA) have published recent studies documenting massive methane leaks from natural gas operations in Colorado and other Western states. He suggested that EPA needs an outside independent review of their process. The EPA said it is seeking more data, but stands by its new estimates. "<ref name="3news">{{cite news| url= http://www.3news.co.nz/Fracking-gas-leak-estimates-lowered/tabid/1160/articleID/295881/Default.aspx |work=3 News | place = NZ |title= Fracking gas leak estimates lowered| date=April 29, 2013}}</ref> An additional concern is that oil obtained through hydraulic fracturing contains chemicals used in hydraulic fracturing, which may increase the rate at which rail tank cars and pipelines corrode, potentially releasing their load and its gases.<ref name="Bloomberg08132013">{{cite news |url=http://www.bloomberg.com/news/2013-08-13/north-dakota-oil-boom-seen-adding-costs-for-rail-safety.html |title= North Dakota Oil Boom Seen Adding Costs for Rail Safety |author=Jim Efstathiou Jr. and Angela Greiling Keane |date=13 August 2013 |agency=[[Bloomberg]] |accessdate=19 January 2012}}</ref><ref name="reuters10112013" >{{cite news |url =http://www.reuters.com/article/2013/10/11/us-tesoro-spill-northdakota-idUSBRE9990VL20131011/|title=Corrosion may have led to North Dakota pipeline leak: regulator | first =Selam |last=Gebrekidan |date=11 October 2013 |publisher= [[Reuters]] |accessdate=31 December 2013}}</ref>
 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.<ref name="LoganJeffrey">{{cite report |title=Natural Gas and the Transformation of the U.S. Energy Sector: Electricity |first=Jeffrey |last=Logan |publisher= Joint Institute for Strategic Energy Analysis | url=http://www.nrel.gov/docs/fy13osti/55538.pdf
@@ Line 27: / Line 27: @@
 In 2008, measured ambient concentrations near drilling sites in [[Sublette County, Wyoming]] were frequently above the National Ambient Air Quality Standards (NAAQS) of 75ppb and have been recorded as high as 125 ppb.<ref name=tribOzoneWyoming/> A 2011 study for the city of [[Fort Worth, Texas]], examining air quality around natural gas sites "did not reveal any significant health threats."<ref name=fortworthtexas/><ref name=starFortWorthNoThreats/> In [[DISH, Texas]], elevated levels of [[disulfide]]s, [[benzene]], [[xylene]]s and [[naphthalene]] have been detected in the air, emitted from the compressor stations.<ref name="DISH TX SciAm"/> People living near shale gas drilling sites often "complain of headaches, diarrhea, nosebleeds, dizziness, blackouts, muscle spasms, and other problems."<ref name="DISH TX EHP"/> Cause-and-effect relationships have not been established in all cases.<ref name="DISH TX EHP" /> 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.<ref name="HeatOnGas"/> 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.<ref name=atthefrontAirImpacts/>
-Also transportation of necessary water volume for hydraulic fracturing, if done by [[truck]]s, can cause high volumes of air emissions, especially particulate matter emissions.<ref name = "BMP" /> There are also reports of health problems around compressors stations<ref name="DISH TX SciAm" />  or drilling sites,<ref name="DISH TX EHP"/> although a causal relationship was not established for the limited number of wells studied<ref name="DISH TX EHP"/> and another Texas government analysis found no evidence of effects.<ref name="TexasDSHS" />
+Also transportation of necessary water volume for hydraulic fracturing, if done by [[truck]]s, can cause high volumes of air emissions, especially particulate matter emissions.<ref name="BMP">{{cite journal | url= http://www.efdsystems.org/Portals/25/Hydraulic%20Fracturing%20BMPs%20White%20Paper.pdf |title= Hydraulic Fracturing: Environmentally Friendly Practices | publisher = Houston Advanced Research Center | first1 = John Michael | last1 = Fernandez | first2 = Matthew | last2 = Gunter |format = PDF | accessdate = 2012-12-29}}</ref> There are also reports of health problems around compressors stations<ref name="DISH TX SciAm" />  or drilling sites,<ref name="DISH TX EHP"/> although a causal relationship was not established for the limited number of wells studied<ref name="DISH TX EHP"/> and another Texas government analysis found no evidence of effects.<ref name="TexasDSHS">{{cite web |title=DISH, TExas Exposure Investigation |url=http://www.dshs.state.tx.us/epitox/consults/dish_ei_2010.pdf | publisher= Texas DSHS |accessdate=27 March 2013}}</ref>
 In [[DISH, Texas]], elevated levels of [[disulphide]]s, [[benzene]], [[xylene]]s and [[naphthalene]] have been detected in the air.<ref name="DISH TX SciAm"/> According to an article in 'Environmental Health Perspectives,' people living near shale gas drilling sites often "complain of headaches, diarrhea, nosebleeds, dizziness, blackouts, muscle spasms, and other problems."<ref name="DISH TX EHP"/> Cause-and-effect relationships have not been established.<ref name="DISH TX EHP" />
 == Water consumption ==
-Hydraulic fracturing uses between {{convert|1.2|and|3.5|e6USgal}} of water per well, with large projects using up to {{convert|5|e6USgal}}. Additional water is used when wells are refractured.<ref name="CRO 2009"/><ref name="Penn State Water" />  An average well requires {{convert |3|to|8|e6USgal|m3}} of water over its lifetime.<ref name="DOE primer"/><ref name = "Penn State Water" /><ref name="ALL-Marcellus"/><ref name="US Geological Survey" />  According to the [[Oxford Institute for Energy Studies]], greater volumes of fracturing fluids are required in Europe, where the shale depths average 1.5 times greater than in the U.S.<ref name="shale Europe" />
+Hydraulic fracturing uses between {{convert|1.2|and|3.5|e6USgal}} of water per well, with large projects using up to {{convert|5|e6USgal}}. Additional water is used when wells are refractured.<ref name="CRO 2009">{{cite report |url= http://www.fas.org/sgp/crs/misc/R40894.pdf |title=Unconventional Gas Shales: Development, Technology, and Policy Issues |author= Andrews, Anthony et al. |date=30 October 2009 |publisher=Congressional Research Service |accessdate=22 February 2012|format = PDF | pages = 7; 23}}</ref><ref name="Penn State Water">{{cite report |title=Water Withdrawals for Development of Marcellus Shale Gas in Pennsylvania. Introduction to Pennsylvania’s Water Resources |first1=Charles W. |last1=Abdalla |first2= Joy R. |last2=Drohan |publisher = [[The Pennsylvania State University]] |quote= Hydrofracturing a horizontal Marcellus well may use 4 to 8 million gallons of water, typically within about 1 week. However, based on experiences in other major U.S. shale gas fields, some Marcellus wells may need to be hydrofractured several times over their productive life (typically five to twenty years or more)|url=http://pubs.cas.psu.edu/FreePubs/pdfs/ua460.pdf | year = 2010 | format = PDF |accessdate=16 September 2012}}</ref>  An average well requires {{convert |3|to|8|e6USgal|m3}} of water over its lifetime.<ref name="DOE primer"/><ref name = "Penn State Water" /><ref name="ALL-Marcellus"/><ref name="US Geological Survey">{{cite report |url=http://ar.water.usgs.gov/Fayetteville_Shale/abstracts.pdf |title=Modeling the Effects of Non-Riparian Surface Water Diversions on Flow Conditions in the Little Red Watershed |last=Cothren |first=Jackson |quote=...each well requires between 3 and 7 million gallons of water for hydraulic fracturing and the number of wells is expected to grow in the future |publisher=U. S. Geological Survey, Arkansas Water Science Center Arkansas Water Resources Center, American Water Resources Association, Arkansas State Section Fayetteville Shale Symposium 2012 |accessdate=16 September 2012 |format = PDF | page = 12}}</ref>  According to the [[Oxford Institute for Energy Studies]], greater volumes of fracturing fluids are required in Europe, where the shale depths average 1.5 times greater than in the U.S.<ref name="shale Europe">{{cite web |last= Faucon |first= Benoît |date= 17 September 2012 | title= Shale-Gas Boom Hits Eastern Europe |url= http://online.wsj.com/article/SB10000872396390443866404577565244220252020.html | publisher= [[WSJ.com]] |accessdate= 17 September 2012}}</ref>
-Concern has been raised over the increasing quantities of water for hydraulic fracturing. Use of water for hydraulic fracturing can divert water from stream flow, [[Water supply network|water supplies]] for municipalities and industries such as [[power generation]], as well as recreation and [[aquatic life]].<ref name=Grist81513>{{cite news|title=Fracking company wants to build new pipeline — for water|url=http://grist.org/news/fracking-company-wants-to-build-new-pipeline-for-water/|accessdate=August 16, 2013|newspaper=Grist|date=August 15, 2013|author=John Upton}}</ref> The large volumes of water required for most common hydraulic fracturing methods have raised concerns for arid regions, such as Karoo in South Africa,<ref name="NYTUrbina30Dec2011"/> and in Pennsylvania,<ref name="Jefferson letter 2008" /><ref name="Snow Shoe letter 2007" /> and in drought-prone Texas, and Colorado in North America.<ref name="water battles" />  It may also require water overland piping from distant sources.<ref name = "ALL-Marcellus" />
+Concern has been raised over the increasing quantities of water for hydraulic fracturing. Use of water for hydraulic fracturing can divert water from stream flow, [[Water supply network|water supplies]] for municipalities and industries such as [[power generation]], as well as recreation and [[aquatic life]].<ref name=Grist81513>{{cite news|title=Fracking company wants to build new pipeline — for water|url=http://grist.org/news/fracking-company-wants-to-build-new-pipeline-for-water/|accessdate=August 16, 2013|newspaper=Grist|date=August 15, 2013|author=John Upton}}</ref> The large volumes of water required for most common hydraulic fracturing methods have raised concerns for arid regions, such as Karoo in South Africa,<ref name="NYTUrbina30Dec2011"/> and in Pennsylvania,<ref name="Jefferson letter 2008">{{cite report|url=http://scrantontimestribune.com/waterproject/352.pdf|last=Janco | first = David F. |date=3 January 2008 |title=PADEP Determination Letter No. 352 Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request. Order: Atlas Miller 42 and 43 gas wells; Aug 2007 investigation; supplied temporary buffalo for two springs, ordered to permanently replace supplies|publisher=Scranton Times-Tribune|accessdate=27 December 2013}}</ref><ref name="Snow Shoe letter 2007">{{cite report|url=http://scrantontimestribune.com/waterproject/970.pdf|last=Janco | first = David F. |date=1 February 2007 |title=PADEP Determination Letter No. 970. Diminution of Snow Shoe Borough Authority Water Well No. 2; primary water source for about 1,000 homes and businesses in and around the borough; contested by Range Resources. Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request.|publisher=Scranton Times-Tribune |accessdate=27 December 2013}}</ref> and in drought-prone Texas, and Colorado in North America.<ref name="water battles" >{{cite news |url = http://www.politico.com/story/2013/06/fracking-water-battle-92862.html|title=Fracking fuels water battles | author=Staff|date=16 June 2013 |work=Politico |agency= Associated Press | accessdate=26 June 2013}}</ref>  It may also require water overland piping from distant sources.<ref name = "ALL-Marcellus" />
-Some producers have developed hydraulic fracturing techniques that could reduce the need for water.<ref name="window.state.tx.us">[http://www.window.state.tx.us/specialrpt/water/gamechangers/fracturing.php Texas Water Report: Going Deeper for the Solution] Texas Comptroller of Public Accounts. Retrieved 2/11/14.</ref>  Using carbon dioxide, liquid propane or other gases instead of water have been proposed to reduce water consumption.<ref>[http://www.technologyreview.com/news/512656/skipping-the-water-in-fracking/ "Skipping the Water in Fracking."]</ref>  After it is used, the propane returns to its gaseous state and can be collected and reused. In addition to water savings, gas fracturing reportedly produces less damage to rock formations that can impede production.<ref name="window.state.tx.us"/> Recycled flowback water can be reused in hydraulic fracturing.<ref name="WEO2011full"/>  It lowers the total amount of water used and reduces the need to dispose of wastewater after use. The technique is relatively expensive, however, since the water must be treated before each reuse and it can shorten the life of some types of equipment.<ref name="WSJ11202012" />
+Some producers have developed hydraulic fracturing techniques that could reduce the need for water.<ref name="window.state.tx.us">[http://www.window.state.tx.us/specialrpt/water/gamechangers/fracturing.php Texas Water Report: Going Deeper for the Solution] Texas Comptroller of Public Accounts. Retrieved 2/11/14.</ref>  Using carbon dioxide, liquid propane or other gases instead of water have been proposed to reduce water consumption.<ref>[http://www.technologyreview.com/news/512656/skipping-the-water-in-fracking/ "Skipping the Water in Fracking."]</ref>  After it is used, the propane returns to its gaseous state and can be collected and reused. In addition to water savings, gas fracturing reportedly produces less damage to rock formations that can impede production.<ref name="window.state.tx.us"/> Recycled flowback water can be reused in hydraulic fracturing.<ref name="WEO2011full"/>  It lowers the total amount of water used and reduces the need to dispose of wastewater after use. The technique is relatively expensive, however, since the water must be treated before each reuse and it can shorten the life of some types of equipment.<ref name="WSJ11202012">{{cite news |first= Alison | last = Sider |first2=Ben |last2= Lefebvre |date= 20 November 2012|title = Drillers Begin Reusing 'Frack Water.' Energy Firms Explore Recycling Options for an Industry That Consumes Water on Pace With Chicago | url = http://online.wsj.com/news/articles/SB10001424052970203937004578077183112409260 | newspaper = The Wall Street Journal |accessdate= 20 October 2013 }}</ref>
 New data shows that water saved by using natural gas combined cycle plants instead of coal steam turbine plants saves 25–50 times more water than the amount of water needed to extract the gas using hydraulic fracturing.<ref>[http://iopscience.iop.org/1748-9326/8/4/045033/article?fromSearchPage=true Drought and the water–energy nexus in Texas] Environmental Research Letters. Retrieved 2/11/14.</ref>
@@ Line 44: / Line 44: @@
 As the fracturing fluid flows back through the well, it consists of spent fluids and may contain dissolved constituents such as minerals and [[brine water]]s. It may account for about 30–70% of the original fracture fluid volume. In addition, natural [[formation water]]s may flow to the well and need treatment. approaches to managing these fluids, commonly known as [[produced water]], include [[underground injection]], municipal and commercial [[wastewater treatment]] and discharge, self‐contained systems at well sites or fields, or recycling to fracture future wells.<ref name=Arthur2/> However, the quantity of waste water needing treatment and the improper configuration of sewage plants have become an issue in some regions of the United States. Much of the wastewater from hydraulic fracturing operations is processed by public sewage treatment plants, which are not equipped to remove radioactive material and are not required to test for it.<ref name="Neshaminy 2009"/><ref name="Urbina 26Feb2011"/>
-Hydraulic fracturing can concentrate uranium, radium, radon and thorium in flowback.<ref name="Weinhold 2012" /> Estimates of the amount of injected fluid returning to the surface vary. Estimates of the fluid that returns to the surface with the gas range from 15-20%<ref name="Ohio DNR" /> to 30–70%. the fluid is often mixed with formation water.<ref name="netldoe" /><ref name=Arthur2/> Additional fluid may return to the surface through abandoned wells or other pathways.<ref name="DetrowS" /> After the flowback is recovered, [[formation water]], usually [[brine]], may continue to flow to the surface, requiring treatment or disposal. Approaches to managing these fluids, commonly known as flowback, [[produced water]], or wastewater, include [[Injection well#Waste disposal|underground injection]], [[sewage treatment|municipal waste water treatment plants]], [[industrial wastewater treatment]], self-contained systems at well sites or fields, and recycling to fracture future wells.<ref name="LoganJeffrey" /><ref name=Arthur2/><ref name="HopeyDon" /><ref name="LitvakAnya"/> One Duke University study reported that "Marcellus [Shale] wells produce significantly less wastewater per unit gas recovered (~35%) compared to conventional natural gas wells.”<ref name="Lutz 2013" /> In Colorado the volume of wastewater discharged to surface streams increased from 2008 to 2011.<ref name="LoganJeffrey" />
+Hydraulic fracturing can concentrate uranium, radium, radon and thorium in flowback.<ref name="Weinhold 2012">{{cite web |last= Weinhold |first= Bob |date= 19 September 2012 |title= Unknown Quantity: Regulating Radionuclides in Tap Water |url= http://ehp.niehs.nih.gov/category/news/page/6/ |quote = Examples of human activities that may lead to radionuclide exposure include mining, milling, and processing of radioactive substances; wastewater releases from the hydraulic fracturing of oil and natural gas wells...  Mining and hydraulic fracturing, or "fracking", can concentrate levels of uranium (as well as radium, radon, and thorium) in wastewater... | work= Environmental Health Perspectives | publisher = [[NIEHS]], [[NIH]] | accessdate = 11 February 2012 }}</ref> Estimates of the amount of injected fluid returning to the surface vary. Estimates of the fluid that returns to the surface with the gas range from 15-20%<ref name="Ohio DNR" >{{cite report |url= http://www.ohiodnr.com/Portals/11/pdf/wastewater-fact-sheet.pdf|title=Waste water (Flowback)from Hydraulic Fracturing |author= Staff |date= |publisher=Ohio Department of Natural Resources |quote= Most of the water used in fracturing remains thousands of feet underground, however, about 15-20 percent returns to the surface through a steel-cased well bore and is temporarily stored in steel tanks or lined pits. The wastewater which returns to the surface after hydraulic fracturing is called flowback|accessdate=29 June 2013|format = PDF}}</ref> to 30–70%. the fluid is often mixed with formation water.<ref name="netldoe" >{{cite report |url= http://www.netl.doe.gov/technologies/oil-gas/Petroleum/projects/Environmental/Produced_Water/00975_MarcellusFlowback.html|title= Sustainable Management of Flowback Water during Hydraulic Fracturing of Marcellus Shale for Natural Gas Production |author= Sandy McSurdy & Radisav Vidic |date= 25 June 2013|publisher=National Energy Technology Laboratory, US Department of Energy |accessdate=29 June 2013|format = PDF}}</ref><ref name=Arthur2/> Additional fluid may return to the surface through abandoned wells or other pathways.<ref name="DetrowS" >{{cite web |url= http://stateimpact.npr.org/pennsylvania/2012/10/09/perilous-pathways-how-drilling-near-an-abandoned-well-produced-a-methane-geyser/ |title=Perilous Pathways: How Drilling Near An Abandoned Well Produced a Methane Geyser| first =Scott | last = Detrow |date=9 October 2012 |work=StateImpact Pennsylvania |publisher= [[NPR]] |quote=As Shell was drilling and then hydraulically fracturing its nearby well, the activity displaced shallow pockets of natural gas — possibly some of the same pockets the Morris Run Coal company ran into  in 1932. The gas disturbed by Shell’s drilling moved underground until it found its way to the Butters well, and then shot up to the surface. Companies have been extracting oil and gas from Pennsylvania’s subsurface since 1859, when Edwin Drake drilled the world’s first commercial oil well.  Over that 150-year timespan, as many as 300,000 wells have been drilled, an unknown number of them left behind as hidden holes in the ground. Nobody knows how many because most of those wells were drilled long before Pennsylvania required permits, record-keeping or any kind of regulation. It’s rare for a modern drilling operation to intersect — the technical term is "communicate" — with an abandoned well. But incidents like Shell’s Tioga County geyser are a reminder of the dangers these many unplotted holes in the ground can cause when Marcellus or Utica Shale wells are drilled nearby. And while state regulators are considering requiring energy companies to survey abandoned wells within a 1,000-foot radius of new drilling operations, the location of nearby wells is currently missing from the permitting process. That’s the case in nearly every state where natural gas drillers are setting up hydraulic fracturing operations in regions with long drilling histories. Regulators don’t require drillers to search for abandoned wells and plug them because, the thinking goes, this is something drillers are doing anyway.|accessdate=29 June 2013}}</ref> After the flowback is recovered, [[formation water]], usually [[brine]], may continue to flow to the surface, requiring treatment or disposal. Approaches to managing these fluids, commonly known as flowback, [[produced water]], or wastewater, include [[Injection well#Waste disposal|underground injection]], [[sewage treatment|municipal waste water treatment plants]], [[industrial wastewater treatment]], self-contained systems at well sites or fields, and recycling to fracture future wells.<ref name="LoganJeffrey" /><ref name=Arthur2/><ref name="HopeyDon">{{cite news |url=http://www.post-gazette.com/stories/local/region/gas-drillers-recycling-more-water-using-fewer-chemicals-210363 |title=Gas drillers recycling more water, using fewer chemicals |first=Don |last=Hopey |date=1 March 2011 |newspaper=Pittsburgh Post-Gazette | accessdate=27 March 2013}}</ref><ref name="LitvakAnya">{{cite news |url=http://www.bizjournals.com/pittsburgh/blog/energy/2012/08/marcellus-flowback-recycling-reaches-90.html |title=Marcellus flowback recycling reaches 90 percent in SWPA. |first=Anya |last=Litvak |date=21 August 2012 |newspaper=Pittsburgh Business Times | accessdate=27 March 2013}}</ref> One Duke University study reported that "Marcellus [Shale] wells produce significantly less wastewater per unit gas recovered (~35%) compared to conventional natural gas wells.”<ref name="Lutz 2013">{{Cite journal |last=Lutz |first=Brian |last2=Lewis |first2=Aurana |last3=Doyle |first3=Martin |url=http://onlinelibrary.wiley.com/doi/10.1002/wrcr.20096/abstract|title=Generation, transport, and disposal of wastewater associated with Marcellus Shale gas development |date=8 February 2013 |journal=Environmental Health Perspectives |publisher=Water Resources Research |pages=647–1197 |volume=49 |issue=2 |accessdate=2013-06-30 |doi=10.1002/wrcr.20096}}</ref> In Colorado the volume of wastewater discharged to surface streams increased from 2008 to 2011.<ref name="LoganJeffrey" />
 In 2013 the vacuum multi-effect membrane distillation system was introduced to treat flowback. It is a hybrid system that uses both distillation and [[reverse osmosis]] to process the water. The water is repeatedly distilled through a membrane onto a collector. The system is operated in a partial vacuum to reduce the water's boiling point to {{convert|50|-|80|C|F}}. The purified result is appropriate for use in irrigation and may be made potable according to the company offering the service. The residual is highly concentrated brine, which can be reinjected or recycled using other technology.<ref>{{cite web|author=Economist |url=http://www.economist.com/news/technology-quarterly/21590757-environmental-technology-combination-two-desalination-techniques-provides |title=Monitor: Clean that up |publisher=The Economist |date=2013-11-30 |accessdate=2013-12-15}}</ref>
@@ Line 55: / Line 55: @@
 ===Methane===
-Groundwater methane contamination is also a concern as it has adverse effect on water quality and in extreme cases may lead to potential explosion.<ref name="Urbina 26Feb2011" /><ref name="Duke study 2010"/> In 2006, over {{convert|7|e6cuft|m3}} of methane were released from a blown gas well in [[Clark, Wyoming]] and shallow groundwater was found to be contaminated.<ref name="AutoZV-23" /> A scientific study reported in the [[PNAS]] investigated concerns over fracking and well water.  The study found high correlations of drilling activity and methane pollution of the drinking water.<ref>[http://www.philly.com/philly/news/special_packages/inquirer/marcellus-shale/Duke_Study_finds_Methane_gas_in_well_water_near_fracking_sites.html "Duke Study finds Methane gas in well water near fracking sites"  May 9, 2011 Philly Inquirer]</ref>  Methane contamination is not always caused by hydraulic fracturing. Drilling for ordinary drinking water wells can also cause methane release. Most recent studies make use of tests that can distinguish between the deep [[thermogenic]] methane released during gas/oil drilling, and the shallower [[biogenic]] methane that can be released during water-well drilling. While both forms of methane result from decomposition, thermogenic methane results from [[geothermal]] assistance deeper underground.<ref name=molofsky/><ref name="AutoZV-32"/>
+Groundwater methane contamination is also a concern as it has adverse effect on water quality and in extreme cases may lead to potential explosion.<ref name="Urbina 26Feb2011" /><ref name="Duke study 2010">{{cite journal|last=Osborn |first=Stephen G.|last2=Vengosh |first2=Avner|last3= Warner |first3= Nathaniel R.|last4=Jackson |first4= Robert B.|title=Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing |date= 2011-05-17 | accessdate=2011-10-14 |journal= [[Proceedings of the National Academy of Sciences of the United States of America]] |doi= 10.1073/pnas.1100682108 |url=http://www.pnas.org/content/108/20/8172.full.pdf| format = PDF| volume = 108 | issue = 20 | pages = 8172–8176}}</ref> In 2006, over {{convert|7|e6cuft|m3}} of methane were released from a blown gas well in [[Clark, Wyoming]] and shallow groundwater was found to be contaminated.<ref name="AutoZV-23">[http://trib.com/news/state-and-regional/blowout-brings-scrutiny-to-energy-company/article_cea4bf57-e246-5acf-ac9d-8c5587ef7f83.html Blowout brings scrutiny to energy company<!-- Bot generated title -->]</ref> A scientific study reported in the [[PNAS]] investigated concerns over fracking and well water.  The study found high correlations of drilling activity and methane pollution of the drinking water.<ref>[http://www.philly.com/philly/news/special_packages/inquirer/marcellus-shale/Duke_Study_finds_Methane_gas_in_well_water_near_fracking_sites.html "Duke Study finds Methane gas in well water near fracking sites"  May 9, 2011 Philly Inquirer]</ref>  Methane contamination is not always caused by hydraulic fracturing. Drilling for ordinary drinking water wells can also cause methane release. Most recent studies make use of tests that can distinguish between the deep [[thermogenic]] methane released during gas/oil drilling, and the shallower [[biogenic]] methane that can be released during water-well drilling. While both forms of methane result from decomposition, thermogenic methane results from [[geothermal]] assistance deeper underground.<ref name=molofsky>{{cite journal |last1=Molofsky |first1=L.J. |last2=Connor |first2=J.A. |last3=Shahla |first3=K.F. |last4=Wylie |first4=A.S. |last5=Wagner |first5=T. |title=Methane in Pennsylvania Water Wells Unrelated to Marcellus Shale Fracturing |journal=[[Oil and Gas Journal]] |publisher=[[Pennwell Corporation]] |date=December 5, 2011 |pages=54–67 |url=http://www.ogj.com/1/vol-109/issue-49/exploration-development/methane-in-pennsylvania-water-full.html |volume=109 |issue=49}}</ref><ref name="AutoZV-32"/>
-According to the 2011 study of the [[MIT Energy Initiative]], "there is evidence of natural gas (methane) migration into freshwater zones in some areas, most likely as a result of substandard well completion practices i.e. poor quality cementing job or bad casing, by a few operators."<ref name="AutoZV-33"/> 2011 studies by the [[Colorado School of Public Health]] and [[Duke University]] also pointed to methane contamination stemming from hydraulic fracturing or its surrounding process.<ref name="Duke study 2010" /><ref name = "AutoZV-32" /> A study by Cabot Oil and Gas examined the Duke study using a larger sample size, found that methane concentrations were related to topography, with the highest readings found in low-lying areas, rather than related to distance from gas production areas. Using a more precise isotopic analysis, they showed that the methane found in the water wells came from both the Marcellus Shale (Middle Devonian) where hydraulic fracturing occurred, and from the shallower Upper Devonian formations.<ref name=molofsky /> A 2013 Duke study suggested that both defective cement seals in the upper part of wells and faulty steel linings within deeper layers may be allowing methane and injected fluid to seep into surface waters.<ref name="EhrenburgR" /> Abandoned gas and oil wells also provide conduits to the surface.<ref name="DetrowS" /> A recent Duke University study found methane concentrations six times higher and ethane concentrations were 23 times higher at residences within a kilometer of a shale gas well. Propane was also detected in 10 homes within a kilometer of drilling. The researchers reported that the methane, ethane and propane data, and new evidence from hydrocarbon and helium content, all suggested that drilling has affected the drinking water. They noted that the ethane and propane data were notable because there was no biological source of ethane and propane in the region and Marcellus gas is higher in both than are Upper Devonian gases.<ref name="PNAS06242013" />
+According to the 2011 study of the [[MIT Energy Initiative]], "there is evidence of natural gas (methane) migration into freshwater zones in some areas, most likely as a result of substandard well completion practices i.e. poor quality cementing job or bad casing, by a few operators."<ref name="AutoZV-33"/> 2011 studies by the [[Colorado School of Public Health]] and [[Duke University]] also pointed to methane contamination stemming from hydraulic fracturing or its surrounding process.<ref name="Duke study 2010" /><ref name = "AutoZV-32" /> A study by Cabot Oil and Gas examined the Duke study using a larger sample size, found that methane concentrations were related to topography, with the highest readings found in low-lying areas, rather than related to distance from gas production areas. Using a more precise isotopic analysis, they showed that the methane found in the water wells came from both the Marcellus Shale (Middle Devonian) where hydraulic fracturing occurred, and from the shallower Upper Devonian formations.<ref name=molofsky /> A 2013 Duke study suggested that both defective cement seals in the upper part of wells and faulty steel linings within deeper layers may be allowing methane and injected fluid to seep into surface waters.<ref name="EhrenburgR">{{cite news |url=http://www.sciencenews.org/view/generic/id/351200/description/News_in_Brief_High_methane_in_drinking_water_near_fracking_sites|title=News in Brief: High methane in drinking water near fracking sites. Well construction and geology may both play a role |first=Rachel |last=Ehrenburg |date=25 June 2013 |publisher=Science News | accessdate=26 June 2013}}</ref> Abandoned gas and oil wells also provide conduits to the surface.<ref name="DetrowS" /> A recent Duke University study found methane concentrations six times higher and ethane concentrations were 23 times higher at residences within a kilometer of a shale gas well. Propane was also detected in 10 homes within a kilometer of drilling. The researchers reported that the methane, ethane and propane data, and new evidence from hydrocarbon and helium content, all suggested that drilling has affected the drinking water. They noted that the ethane and propane data were notable because there was no biological source of ethane and propane in the region and Marcellus gas is higher in both than are Upper Devonian gases.<ref name="PNAS06242013">{{Cite news |last=Jackson |first=Robert B.|last2=Vengosh |first2=Avner |last3=Darrah |first3= Thomas|last4=Warner |first4=Nathaniel R. |url=http://www.pnas.org/cgi/doi/10.1073/pnas.1221635110 |title=Increased Stray Gas Abundance in a Subset of Drinking Water Wells Near Marcellus Shale Gas Extraction|date=24 June 2013 |journal=Proceedings of the National Academy of Sciences |publisher=ACS Publications}}</ref>
 The Colorado Oil & Gas Conservation Commission has found some wells containing thermogenic methane due to oil and gas development upon investigating complaints from residents.<ref name="AutoZV-32"/>  A review published in February 2012 found no direct evidence that fracking's actual injection phase resulted in contamination of ground water, and suggests that reported problems occur due to leaks in its fluid or waste storage apparatus; the review says that methane in water wells in some areas probably comes from natural resources.<ref name =FrackMix1/><ref name=FrackMix2/>
@@ Line 66: / Line 66: @@
 There are concerns about possible contamination by hydraulic fracturing fluid both as it is injected under high pressure into the ground and as it returns to the surface.<ref name = "NYT Waste Docs 26Feb2011" /><ref name="EhrenburgR" /> To mitigate the effect of hydraulic fracturing on groundwater, the well and ideally the shale formation itself should remain hydraulically isolated from other geological formations, especially freshwater aquifers.<ref name = "WEO2011full" />
-While some of the [[List of additives for hydraulic fracturing|chemicals used in hydraulic fracturing]] are common and generally harmless, some are known [[carcinogens]].<ref name="house1" />  Out of 2,500&nbsp;hydraulic fracturing products, more than 650 contained known or possible human carcinogens regulated under the [[Safe Drinking Water Act]] or listed as hazardous air pollutants".<ref name = "house1" /> Between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their [[Occupational Safety and Health Administration]] (OSHA) required [[material safety data sheet]] (MSDS). The MSDS is a list of chemical components in the products of chemical manufacturers, and according to OSHA, a manufacturer may withhold information designated as "proprietary" from this sheet. Most companies participating in the investigation were unable to name the ingredients of the products they use, leading the committee to surmise these "companies are injecting fluids containing unknown chemicals about which they may have limited understanding of the potential risks posed to human health and the environment".<ref name="house1"/> Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it more difficult to prove that hydraulic fracturing is contaminating the environment with these substances.<ref name = "AutoZV-16" />
+While some of the [[List of additives for hydraulic fracturing|chemicals used in hydraulic fracturing]] are common and generally harmless, some are known [[carcinogens]].<ref name="house1" />  Out of 2,500&nbsp;hydraulic fracturing products, more than 650 contained known or possible human carcinogens regulated under the [[Safe Drinking Water Act]] or listed as hazardous air pollutants".<ref name = "house1" /> Between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their [[Occupational Safety and Health Administration]] (OSHA) required [[material safety data sheet]] (MSDS). The MSDS is a list of chemical components in the products of chemical manufacturers, and according to OSHA, a manufacturer may withhold information designated as "proprietary" from this sheet. Most companies participating in the investigation were unable to name the ingredients of the products they use, leading the committee to surmise these "companies are injecting fluids containing unknown chemicals about which they may have limited understanding of the potential risks posed to human health and the environment".<ref name="house1"/> Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it more difficult to prove that hydraulic fracturing is contaminating the environment with these substances.<ref name="AutoZV-16">{{cite web |url= http://sites.duke.edu/sjpp/2011/ensuring-safe-drinking-water-in-the-age-of-hydraulic-fracturing/ |title= Ensuring Safe Drinking Water in the Age of Hydraulic Fracturing |author=Kris Fitz Patrick |quote=The most fundamental recommendation is for states to rigorously test their ground water before and after hydraulic fracturing takes place. A major difficulty in proving or disproving contamination in previous cases has been the lack of a baseline sample for the water supply in question. The group also raises a federal policy issue, namely whether fracturing fluids should continue to be exempt from Safe Drinking Water Act regulations. This exemption was an informal one until 2005, when it was codified as part of the Energy Policy Act. A consequence of this exemption is that drilling companies are not required to disclose the chemicals that make up the fracturing fluids, making testing for these chemicals in ground water more difficult.|date=November 17, 2011}}</ref>
-Another 2011 study identified 632&nbsp;chemicals used in natural gas operations. Only 353 of these are well-described in the scientific literature. The study indicated possible long-term health effects that might not appear immediately.  The study recommended full disclosure of all products used, along with extensive air and water monitoring near natural gas operations; it also recommended that hydraulic fracturing's exemption from regulation under the US [[Safe Drinking Water Act]] be rescinded.<ref name = "AEHS 2011" /> Industry group ''Energy In Depth'', a research arm of the Independent Petroleum Association of America, contends that fracking "was never granted an 'exemption' from it... How can something earn an exemption from a law that never covered or even conceived of it in the first place?”<ref name="EnergyInDepth01" />
+Another 2011 study identified 632&nbsp;chemicals used in natural gas operations. Only 353 of these are well-described in the scientific literature. The study indicated possible long-term health effects that might not appear immediately.  The study recommended full disclosure of all products used, along with extensive air and water monitoring near natural gas operations; it also recommended that hydraulic fracturing's exemption from regulation under the US [[Safe Drinking Water Act]] be rescinded.<ref name="AEHS 2011">{{cite journal |last=Colborn |first=Theo |last2=Kwiatkowski |first2=Carol |last3=Schultz |first3=Kim |last4=Bachran |first4=Mary |year=2011 |title=Natural Gas Operations from a Public Health Perspective |journal=Human and Ecological Risk Assessment: An International Journal |volume=17 |issue=5 |publisher=[[Taylor & Francis]] |pages=1039–1056 |url=http://www.pasdegazdeschistes.rd-h.fr/wp-content/uploads/NaturalGasManuscriptPDF09_13_10-Th%C3%A9o-Colborn.pdf |doi=10.1080/10807039.2011.605662|format = PDF}}</ref> Industry group ''Energy In Depth'', a research arm of the Independent Petroleum Association of America, contends that fracking "was never granted an 'exemption' from it... How can something earn an exemption from a law that never covered or even conceived of it in the first place?”<ref name="EnergyInDepth01">{{cite web |title=FAQ: Hydraulic Fracturing, SDWA, Fluids, and DeGette/Casey |url=http://www.energyindepth.org/wp-content/uploads/2009/03/faq_hf_sdwa_fluids_degettecasey.pdf | publisher=Energy In Depth | accessdate=27 March 2013}}</ref>
-Governments are responding to questions about the contents of hydraulic fracturing fluid by requiring disclosure via government agencies and public web site. The Irish regulatory regime requires full disclosure of all additives to Ireland's Environmental Protection Agency (Ireland). The European Union also requires such disclosure.<ref name="EU" /> In the US, the Ground Water Protection Council launched FracFocus.org, an online voluntary disclosure database for hydraulic fracturing fluids funded by oil and gas trade groups and the U.S. Department of Energy. The site has been met with some skepticism relating to proprietary information that is not included.<ref name = "HassBenjamin" /><ref name="SoraghanMike02" /> Some states have mandated fluid disclosure  and incorporated FracFocus as the tool for disclosure.<ref name="WatsonMatt"/><ref name = "MaykuthAndrew" /> Also in the US, [[The FracTracker Alliance]] provides oil and gas-related data storage, analyses, and online and customized maps related to hydraulic fracturing on FracTracker.org.<ref name="PlainDealer04042013" /><ref name="FracTracker" />
+Governments are responding to questions about the contents of hydraulic fracturing fluid by requiring disclosure via government agencies and public web site. The Irish regulatory regime requires full disclosure of all additives to Ireland's Environmental Protection Agency (Ireland). The European Union also requires such disclosure.<ref name="EU">{{cite report |url=http://www.epa.ie/pubs/reports/research /sss/UniAberdeen_FrackingReport.pdf|title= Hydraulic Fracturing or ‘Fracking’: A Short Summary of Current Knowledge and Potential Environmental Impacts A Small Scale Study for the Environmental Protection Agency (Ireland) under the Science, Technology, Research & Innovation for the Environment. (STRIVE) Programme 2007 |author= Dave Healy |date= July 2012|publisher= Environmental Protection Agency, Ireland |accessdate=28 July 2013|format = PDF}}</ref> In the US, the Ground Water Protection Council launched FracFocus.org, an online voluntary disclosure database for hydraulic fracturing fluids funded by oil and gas trade groups and the U.S. Department of Energy. The site has been met with some skepticism relating to proprietary information that is not included.<ref name="HassBenjamin">{{cite news |url=http://www.bloomberg.com/news/2012-08-14/fracking-hazards-obscured-in-failure-to-disclose-wells.html |title=Fracking Hazards Obscured in Failure to Disclose Wells |first=Benjamin |last=Hass |date=14 August 2012 |newspaper=Bloomberg News |accessdate=27 March 2013}}</ref><ref name="SoraghanMike02">{{cite news |url=http://www.eenews.net/eenewspm/2012/06/21/archive/2 |title=White House official backs FracFocus as preferred disclosure method |first=Mike |last=Soraghan |date=13 December 2013 |newspaper=E&E News | accessdate=27 March 2013}}</ref> Some states have mandated fluid disclosure  and incorporated FracFocus as the tool for disclosure.<ref name="WatsonMatt">{{cite web |title=Colorado Sets The Bar on Hydraulic Fracturing Chemical Disclosure |url=http://blogs.edf.org/energyexchange/2011/12/13/colorado-sets-the-bar-on-hydraulic-fracturing-chemical-disclosure | publisher= Environmental Defense Fund |accessdate=27 March 2013}}</ref><ref name="MaykuthAndrew">{{cite news |url=http://articles.philly.com/2012-01-22/business/30652980_1_fracking-marcellus-shale-coalition-chemical-disclosure |title=More states ordering disclosure of fracking chemicals. |first=Andrew |last=Maykuth |date=22 January 2012 |newspaper=Philadelphia Inquirer | accessdate=27 March 2013}}</ref> Also in the US, [[The FracTracker Alliance]] provides oil and gas-related data storage, analyses, and online and customized maps related to hydraulic fracturing on FracTracker.org.<ref name="PlainDealer04042013">{{cite news |url =http://www.cleveland.com/business/index.ssf/2013/04/fractracker_monitors_shale_dev.html|title=FracTracker monitors shale development in Ohio | first = Alison|last=Grant |date= 4 April 2013 |publisher= [[The Plain Dealer]] | accessdate=28 July 2013}}</ref><ref name="FracTracker">{{cite news |url =http://www.fractracker.org/|title=FracTracker. Exploring data, sharing perspectives, and mapping impacts of the gas industry  | first = |last=Staff |date= |publisher= FracTracker | accessdate=28 July 2013}}</ref>
 ===Radioactivity===