Water Consumption
The large volumes of water required have raised concerns about hydraulic fracturing in arid areas, such as Karoo in South Africa and drought prone areas of North America. During periods of low stream flow it may affect water supplies for municipalities and industries such as power generation, as well as recreation and aquatic life. It may also require water overland piping from distant sources.
Hydraulic fracturing uses between 1.2 and 3.5 million US gallons (4.5 and 13 Ml) of water per well, with large projects using up to 5 million US gallons (19 Ml). Additional water is used when wells are refractured. An average well requires 3 to 8 million US gallons (11,000 to 30,000 m3) of water over its lifetime. Using the case of the Marcellus Shale as an example, as of 2008 hydraulic fracturing accounted for 650 million US gallons per year (2,500,000 m3/a) or less than 0.8% of annual water use in the area overlying the Marcellus Shale. The annual number of well permits, however, increased by a factor of five and the number of well starts increased by a factor of over 17 from 2008 to 2011. 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. To minimize water consumption, recycling is one possible option. In the Spring of 2013, new hydraulic fracturing water recycling rules were adopted in the state of Texas by the Railroad Commission of Texas. The Water Recycling Rules are intended to encourage Texas hydraulic fracturing operators to conserve water used in the hydraulic fracturing process for oil and gas wells. Another possible option is to use carbon dioxide instead of water.
Injected fluid
See also: List of additives for hydraulic fracturing
While some of the chemicals used in hydraulic fracturing are common and generally harmless, some are known carcinogens at high enough doses. A report prepared for House Democratic members Henry Waxman, Edward Markey and Diana DeGette stated that out of 2,500 hydraulic fracturing products, "more than 650 of these products contained chemicals that are known or possible human carcinogens, regulated under the Safe Drinking Water Act, or listed as hazardous air pollutants". The report also shows that 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. When asked to reveal the proprietary components, most companies participating in the investigation were unable to do so, 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". 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.
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. 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?”
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. 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. Some states have mandated fluid disclosure and incorporated FracFocus as the tool for disclosure. Also in the US, FracTracker Alliance provides oil and gas-related data storage, analyses, and online and customized maps related to hydraulic fracturing on FracTracker.org.
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 or disposal. These fluids, commonly known as flowback, produced water, or wastewater, are managed by underground injection, wastewater treatment and discharge, or recycling to fracture future wells. Hydraulic fracturing can concentrate levels of uranium, radium, radon, and thorium in flowback. Treatment of produced waters may be feasible through either self-contained systems at well sites or fields or through municipal waste water treatment plants or commercial treatment facilities. However, the quantity of waste water being treated, and the improper configuration of sewage plants to treat it, have become an issue in the northeast United States. Much of the wastewater from hydraulic fracturing operations in Pennsylvania is processed by public sewage treatment plants, which are not equipped to remove radioactive material and are not required to test for it. Another issue is the bromide in waste brine. The bromide combines with chlorine disinfectant and dissolved organic matter in water treatment plants to form trihalomethanes (THMs).
Interestingly, a recent study from Duke University found: “Contrary to current perceptions, Marcellus [Shale] wells produce significantly less wastewater per unit gas recovered (~35%) compared to conventional natural gas wells.” Estimates of the amount of injected fluid returning to the surface vary. Some say approximately 15-20% of the injected fluid returns to the surface with the gas and other that higher amounts return. Some remains underground and some may return to the surface through abandoned wells or other pathways. Although not necessarily indicative of broader industry trends, several reports have also highlighted an industry-wide shift toward greater water recycling in the Marcellus Shale.
Methane
Groundwater methane contamination is also a concern as it has adverse impact on water quality and in extreme cases may lead to potential explosion. 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. However, methane contamination is not always caused by hydraulic fracturing. Drilling for ordinary drinking water wells can also cause methane release. Some 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.
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." 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. 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. 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. Abandoned gas and oil wells also provide conduits to the surface.
In April 2013 the EPA dramatically lowered its estimate of how much methane gas is released to the atmosphere during the fracking process by 20 percent.
Radioactivity
See also: Radionuclides associated with hydraulic fracturing
In 2011 The New York Times reported radium in wastewater from natural gas wells is released into Pennsylvania rivers, and has compiled a map of these wells and their wastewater contamination levels, and stated that some EPA reports were never made public. The Times' reporting on the issue has come under some criticism. Recycling this wastewater has been proposed as a partial solution, but this approach has limitations. A 2012 study examining a number of hydraulic fracturing sites in Pennsylvania and Virginia by Pennsylvania State University, found that water that flows back from gas wells after hydraulic fracturing contains high levels of radium. Solid waste such as drill clippings is also radioactive. In 2012 there were 1325 radiation alerts from all sources at dumps in Pennsylvania, up from 423 alerts in 2008. At least 1,000 of the 2012 alerts were set off by waste from gas and oil drilling hydraulic fracturing operations.
Seismicity
Hydraulic fracturing routinely produces microseismic events much too small to be detected except by sensitive instruments. These microseismic events are often used to map the horizontal and vertical extent of the fracturing. However, as of late 2012, there have been three instances of hydraulic fracturing, through induced seismicity, triggering quakes large enough to be felt by people: one each in the United States, Canada, and England.
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 (Mw).
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.” 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.
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.
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.
Induced seimicity 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. Although the magnitudes of these quakes has been small, the USGS says that there is no guarantee that larger quakes will not occur. In addition, the frequency of the quakes has been increasing. In 2009, there were 50 earthquakes greater than magnitude 3.0 in the area spanning Alabama and Montana, and there were 87 quakes in 2010. In 2011 there were 134 earthquakes in the same area, a sixfold increase over 20th century levels. There are also concerns that quakes may damage underground gas, oil, and water lines and wells that were not designed to withstand earthquakes.
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, according to seismologists at Columbia University. 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.
Health impacts
Concern has been expressed over the possible long and short term health effects of air and water contamination and radiation exposure by gas production. A study on the effect of gas drilling, including hydraulic fracturing, published by the Cornell University College of Veterinary Medicine, concluded that exposure to gas drilling operations was strongly implicated in serious health effects on humans and animals although scientists have raised concerns about that particular report. As of May 2012, the United States Institute of Medicine and United States National Research Council were preparing to review the potential human and environmental risks of hydraulic fracturing.
The U.S. Environmental Protection Agency considers radioactive material in flowback a hazard to workers at hydraulic fracturing sites. Workers may inhale radon gas released by the process, raising their risk of lung cancer. They are also exposed to alpha and gamma radiation released during the decay of radium-226 and to gamma radiation and beta particles released by the decay of radium-228, according to EPA. EPA reports that gamma radiation can also penetrate the skin and raise the risk of cancer.
A 2012 study concluded that risk prevention efforts should be directed towards reducing air emission exposures for persons living and working near wells during well completions. In the United States the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) released a hazard alert based on data collected by NIOSH that workers may be exposed to dust with high levels of respirable crystalline silica (silica dioxide) during hydraulic fracturing. NIOSH notified company representatives of these findings and provided reports with recommendations to control exposure to crystalline silica and recommend that all hydraulic fracturing sites evaluate their operations to determine the potential for worker exposure to crystalline silica and implement controls as necessary to protect workers.
According to the United States Department of Energy, hydraulic fracturing fluid is composed of approximately 95% water, 4.5% sand and 0.5% different chemicals. These percentages are by weight, so hydraulically fracturing a well uses 4-7 million gallons of water (15000-27000 tons) and 80-140 tons of chemicals. There can be up to 65 chemicals and often include benzyne, glycol-ethers, toluene, ethanol and nonphenols. Some have argued that although many of these chemicals are harmful, some of them are either non toxic or are non toxic at lower dosages. However, their concentration in hydraulic fracturing fluid have proven toxic to animals and humans. Many chemicals used in fracking, such as 2-BE ethylene glycol, are carcenogenic. This chemical is listed under chronic oral RFD assessment, chronic inhalation RFC assessment, and carcinogenicity assessment records of the US environmental protection agency’s website. In a study done by the US Environmental Protection Agency, it found statistically significant effects observed in mice included forestomach ulcers and epithelial hyperplasia, hematopoietic cell proliferation and hemosiderin pigmentation in the spleen, Kupffer cell pigmentation in the livers, and bone marrow hyperplasia (in males only, suggesting tissue damage due to exposure above 125-250ppm. The study also found statistically significant decreases in automated and manual hematocrit (Hct) values, hemoglobin (Hb) concentrations, and red blood cell (RBC) for both males and females at exposure of 250ppm and for female in the 125ppm exposure group.
In a study done by Colborn and colleagues, they examined 353 out of 994 fracking chemicals identified by TEDX in hydraulic fracking operation. They found over 75% of the 353 chemicals affected the skin, eyes, and other sensory organs,52% affected the nervous system, 40% affected the immune system and kidney system, and 46% affected the cardiocascular system and blood.
In a second study done by Colborn and colleagues, they examined the airborne chemicals due to the fracking process. The group categorized the human tissue types into 12 categories and found 35 chemicals affected the brain/nervous system, 33 the liver/ metabolism, and 30 the endocrine system, which includes reproductive and developmental effects. The categories with the next highest numbers of effects were the immune system (28), cardiovascular/blood (27), and the sensory and respiratory systems (25 each). Eight chemicals had health effects in all 12 categories.
Airborne chemicals during the fracking process, such as benzene and benzene derivatives, naphthalene, methylene chloride, are either carcinogenic or suspected as a human carcinogen to the human body.
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