For the past couple of weeks, I have been writing a paper on the environmental and health impacts of hydraulic fracturing. This topic is near and dear to my heart because I live near a natural gas drilling site. Just a half hour away, there is a drilling site in Cameron, WV. Trucks drive by my house at all hours of the day and night. Although natural gas is cheap and will help the United States become self sufficient in regards to their energy consumption and production, I am in favor of more renewable sources of energy, like wind and sun. While trying to remain unbiased, I tried to point out the most common environmental and health concerns in regards to hydraulic fracturing. I hope you enjoy and learn a little bit about what is happening right next door. And as always, if you chose to use some of my work, please use the proper citations and do not plagiarize.
Environmental and Health Implication from Hydraulic Fracturing
By Jasmin Russell
Leading International Development, Summer 2012
The Marcellus Shale is a grouping of sedimentary rock found in the Appalachian region of the United States. It spans the states of New York, Pennsylvania, West Virginia, Ohio, Maryland, New Jersey, and a small portion of the states of Kentucky and Tennessee. This shale contains a large amount of untapped natural gas reserves. In order to remove these natural gas reserves, hydraulic fracturing, also known as “fracking”, is often used. Hydraulic fracturing is a horizontal drilling process used to extract the natural gas from the shale thousands of feet underground.
Although there are benefits to using the hydraulic fracturing method to remove natural gas from the bedrock, such as energy security and job creation, there are also downfalls, specifically towards environmental and human health issues. The negative environmental ramifications of hydraulic fracturing can consequentially cause harm the health of local residents, pets, and wildlife through various pathways such as water and air contamination.
The issue of how hydraulic fracturing affects the environment and subsequently, the local residents, is important for various reasons. Firstly, hydraulic fracturing is becoming common practice in the natural gas industry. According to the American Petroleum Institute, “Hydraulic fracturing will account for nearly 70 percent of natural gas development in the future” (March 2012, p.1). Secondly, about 0.5% of hydraulic fracturing fluid contains chemicals, some of which are known carcinogens. Thirdly, due to the nature of the Marcellus Shale, much of the gas formations are located in residential areas. If there are negative environmental by-products of hydraulic fracturing, they can affect local resident within close proximity to the drilling sites.
The following table lists and defines the key terms used in the process of hydraulic fracturing. Although all terms are not included in this table, they may be further identified within this paper. All definitions were gathered from the American Petroleum Institute.
|Aquifer||A subsurface formation that is sufficiently permeable to conduct groundwater and to yield economically significant quantities of water to wells and springs|
|Basin||A closed geologic structure in which the beds dip toward a central location; the youngest rocks are at the center of a basin and are partly or completely ringed by progressively older rocks.|
|Casing||Steel piping positioned in a wellbore and cemented in place to prevent the soil or rock from caving in. It also serves to isolate formations and water zones from production fluids, such as water, gas and oil, from the surrounding geologic formations.|
|Flowback||The fracture and produced fluids that return to surface after a hydraulic fracture is completed|
|Fracturing fluids||A mixture of water, proppant (often sand) and additives used to hydraulically induce cracks in the target formation|
|Groundwater||Subsurface water (fresh or saline) that is in the zone of saturation; source of water for wells, seepage and springs. The top surface of the groundwater is the water table.|
|Hydrocarbons||Any of numerous organic compounds, such as methane (the primarily component of natural gas), that contain only carbon and hydrogen.|
|Produced Water||Any of the many types of water produced from oil and gas wells.|
|Water Quality||The chemical, physical and biological characteristics of water with respect to its suitability for a particular use|
Hydraulic Fracturing Process
The process of hydraulic fracturing begins with a wellbore being drilled with a drill pipe and bit. Simultaneously, mud is pumped into the wellbore to lubricate the drill pipe and bit. The drilling passes through the aquifer level until it reaches the shale, which is thousands of feet underground. After the depth has been drilled, the drill pipe and bit are removed and a steel tube called casing is placed inside the well. The casing provides a protective layer against the surrounding ground and aquifer. Cement is then pumped through the casing. The layer of cement creates a barrier between the casing and aquifer level, protecting the underground water. The casing is then pressure tested to ensure hydrocarbons and other chemicals do not leak out into the surrounding ground. There are multiple layers of casing and cement used to protect the surrounding soil and water.
Once the wellbore has been constructed, a drilling motor is operated to drill horizontally. Once the angled drilling is finished, the cementing and casing is continued throughout the whole wellbore. Next, a perforating tool is used to create fissures in the shale layer. Fissures are line of breakage or fractures made by cracking or splitting the shale. Fracturing fluid is then pumped into the pipe creating to collect the natural gas. Water from the fracturing fluid is removed but the proppant remains, allowing the gas to travel from the shale into the well. Once all the fractures have been made, the gas is collected.
Environmental and Health Implications of Hydraulic Fracturing
While hydraulic fracturing is a cleaner energy alternative compared to other sources of energy, for example coal, the process does not come without its risks to the environment. Hydraulic fracturing can pollute water sources, reduce air quality, and is hypothesized to induce seismic activity. This method of gathering natural gas reduces the amount of readily available water, reduces the water quality, pollutes the air through the air exposure of chemical used in fracking, and allows for the settling of the shale caused by the created fissures, which may stress pre-existing fault lines.
Water Use and Pollution
“Each fracking event requires 2-4 million gallons of water. The EPA estimates 35,000 wells undergo fracking annually in the United States, requiring the amount of water consumed in a year by some 5 million people” (Schmidt, August 2011, p. A352). The process of hydraulic fracturing consumes great quantities of water and when combined with a rising population and global warming, water quantity is threatened. Furthermore, the wastewater created would not be fit for human consumption due to irregular levels of total dissolved solids, fracturing fluid additives, metals, and naturally occurring radioactive materials. According to the United States Environmental Protection Agency, “Levels of total solids that are too high or too low can also reduce the efficiency of wastewater treatment plants, as well as the operation of industrial processes that use raw water” (June 2004, p.1).
The 2-4 million of gallons of water per hydraulic fracturing site is used towards creating the mud to reduce the friction of the drill pipe and bit during the development process and in the fracturing fluid used to transport the natural gas. Fracturing fluid contains roughly 99.5% of water and proppant, typically sand, and 0.5% chemical additives. Although the percentage of chemicals in fracturing fluid seems insignificant, “ [that] small percentage of the total… can nevertheless add up to the hundreds of thousands of gallons injected directly into the ground” (Schmidt, August 2011, p. A352).
The additives in fracking fluids can vary widely because they are modified for each specific drill site and are used for different purposes as dictated by the site. “A variety of chemicals – among them methanol, formaldehyde, ethylene glycol, hydrochloric acid, and sodium hydroxide – are used for purposed such as improving fluid viscosity, inhibiting corrosion, and limiting bacterial growth.” (Manuel, May 2010, p.A199). Not all of the chemicals used in fracking fluids are fully biodegradable and may remain in the shale if not fully removed.
Although the aquifer level is typically protected by the wellbore casing, which is pressure tested to ensure that there is no leakage of hydrocarbons or other chemicals, the fracking fluid, which is injected into the fissures in the shale, may not be fully retrieved during the flowback process. According to the EPA, “…between 20 to 30 percent of the BTEX injected is expected to remain in the formation” (June 2004, p. 4-16). BTEX is an acronym for the chemicals benzene, toluene, ethylbensene, and xylene. These chemicals can potentially migrate and contaminate underground drinking water if they remain in shale fissures. As a result, it is hypothesized that, “nearly 2% of such gas wells may end up contaminating groundwater with fracking fluids” (Holzman, July, 2011, p. A289).
Health Concerns Pertaining to Fracking Fluids
Fracking fluids are made up of many different products, which are used for many different purposes. These different products contain chemical compositions, which of which can be harmful to humans. If fracking fluids make their way into underground sources of drinking water, though continuous exposure, they may adversely affect local residents, especially children. “Research has also shown that children are not able to metabolize some toxicants as well as adults due to immature detoxification processes. Moreover, the fetus and young child are in a critical period of development when toxic exposures can have profound negative effects” (AOEC, 2001, p.3). These negative effects can range from mild irritation to birth defects, to causing cancer. The main categories for fluid products are gelled fluids, foamed gels, plain water and potassium chloride water, acids, and combination treatments.
Gelled fluids include linear and cross-linked gels. Linear gels are used to thicken the water to create a higher viscosity. The higher the viscosity, the easier it is to transport proppant. Linear gels can contain any of the following ingredients: water, guar gum, diesel, fumaric acid, or adipic acid. These chemicals can cause eye, skin, respiratory irritation, and if diesel is used, it is considered carcinogenic (EPA, June 2004, p.9). Cross-linked gels are combined with linear gels. They reduce the need for fluid thickeners, create an even higher viscosity, and extend the life of the fracturing fluid. Cross-linked gels can contain any of the following ingredients: boric acid, ethylene glycol, monoethanolamine, and sodium tetraborate. These chemicals are only mild eye and skin irritants (Ibid).
Foamed gels are used to create bubbles that transport proppant into the fractures. They also suspend the natural gas and it returns to the surface. Foamed gels can contain isopropanol, salt, diethanolamine, ethanol, 2-butoxyethanol, ester salt, polyglycol ether, and water. These chemicals are linked to kidney and liver effects; eye, skin, and respiratory irritation; skin disorders and eye ailments; as well as nausea headaches and narcosis (Ibid).
Acids are used to dissolve the rock to allow for the formation water and methane to travel. Thousands of gallons of acid are used per fracking site. The acids can also be used to clean up perforation around the well casing to ease the injection of fracking fluid. The acids used are typically hydrochloric acid and formic acid of which prolonged exposure can cause erosion of teeth, severe burns, tissue damage, and genetic damage in humans (Ibid).
Lastly, combination treatments or additives are added to the fracking fluid to increase the odds of success of the fracking fluid treatment. The additives can be breakers, which enhance fracturing fluid flowback recovery; biocides, which reduce the incidence of bacterial growth that can lessen the effectiveness of the fracking fluid treatment; fluid-loss additives, which decreased the amount of fracking fluid leakoff and increasing the amount of fluid recovery; friction reducers, which reduces the friction between the casing and the fluid; and acid corrosion inhibitors, which prevent corrosion of the well casing due to the added acid in the fracking fluid. These additives can contain the following chemicals: diammonium peroxidisulphate, 2-bromo-2 nitrol, 3-propanedol, 2-dibromo-3-nitrilopropionamide, 2-bromo-3-nitrilopropionamide, methanol, propargly alcohol, pyridinium, ethyl methyl derivatives, chlorides, thiourea, propan-2-ol, poly (oxy-1,2-ethanediyl)-nonylphenyl-hydroxy, and water. These chemicals may cause eye irritation, skin disorders, respiratory irritation; coughing, pain, dermatitis, nausea, diarrhea, and can cause damage to the eye, blood, lung, liver, kidney, heart, central nervous system, mucus membranes, and spleen (Ibid).
Fracturing fluids and processed water can also cause environmental concerns due to the methods of storage and disposal of the natural gas. When water returns from the wellbore it is known as flowback water or produced water. This flowback water contains fracturing fluid chemicals, naturally occurring radioactive chemicals, and brine. This water is either stored on site in basins or impoundments, or is taken to treatment plants. When flowback water is stored on site in a lined basin, it is often uncovered, leaving it open to evaporation and potentially accessible to wild animals. When fracking fluids are, “…placed in evaporation ponds on the surface, from which chemicals including VOCs can be released to the atmosphere [,] Methane and fracking chemicals can also migrate into shallow aquifers used for drinking water wells.” (Brown, February 2007, p. A76).
Air pollution can also occur during the process of extraction. If fracking fluids are spilled, or there are leaking valves, it is possible to VOC (volatile organic compounds) to be released into the air. Furthermore, “… flowback and produced water from shale layers themselves contain organic compounds that could offgas into the environment when brought to the surface” (Volz et al, 2010).
Additionally, as fore mentioned, hydraulic fracturing requires large quantities of water. The Marcellus Shale is located in and around the Appalachian mountain range. It is not unusual for drilling sites to be located in rural areas, which can only be reached through local roads in mountainous terrain. “Since each fracturing event at each well requires up to 2,400 industrial truck trips, residents near the site and along the truck routes may be exposed to increased levels of these air pollutants” (AOEC, 2001, p.2).
Health Implications Pertaining to Hydraulic Fracturing VOCs
Volatile organic chemicals tend to occur in a couple of distinct areas when it pertains to hydraulic fracturing. Typically, VOCs occur during the flowback process, through the use of hydraulic fracturing machinery, and through the amount of high traffic going to and from the well sites. “Data released on flowback water from wells in Pennsylvania reveal that numerous volatile organic chemicals are returning to the surface, sometime in high concentrations. The Pennsylvania Department of Environmental Protection looked for 70 volatile organic compounds in flowback, and 27 different chemicals showed up” (Earthworks, Hydraulic Fracturing 101). When fracking fluids are not captured properly, they can become airborne and can contribute to ground-level ozone. Ground level ozone is known to heighten the incidences and the severity of asthma and respiratory problems. Moreover, “…when compressor stations undergo periodic maintenance, their gas contents are either flared or vented directly into the air, increasing the risk of exposure for local residents, pets, and livestock…” (Schmidt, August 2011, p. A351). When VOCs are released into the air, they can be inhaled, ingested and absorbed through the skin. This allows for increased exposure to the harmful chemicals involved in hydraulic fracturing. And if humans come in contact with VOCs, they, “…can cause symptoms such as headaches, loss of coordination, and damage to the liver and kidneys” (Brown, February 2007, p. A76)
Induced Seismic Activity
Earthquakes occur when the Earth’s outer crust moves suddenly, releasing built-up stress. These movements typically occur around pre-existing fault lines. It is hypothesized that the process of hydraulic fracturing can induce seismic activity by adding to the stress of these pre-existing fault lines by discarding wastewater through disposal injection wells. This is a topic of concern because although induced earthquakes are not likely to grander is size compared to naturally occurring earthquakes, “…human activity can substantially increase the number of earthquakes a region experiences” (Perry et al, 2011, p.8).
According to the American Natural Gas Alliance (2012), “There are nearly 150,000 disposal injection wells in America, with only a handful potentially linked to modest seismic events”. Disposal injection wells should not be confused with hydraulic fracturing wells. Hydraulic fracturing wells inject large quantities of fluid (about 3,000 gallons per minute) within a short amount of time, with the majority of the fluid returning to surface. Disposal wells inject liquid waste at a rate of 300 gallons per minute over an extended period of time, and stores billions of gallons of waste fluid that permanently remains underground. This storage of product water of a disposal injection well compared to the hydraulic fracturing is more likely to trigger an induced earthquake because, “…fluid in the rock (“pore fluid”) plays a key role in the state of stress and in the rock failure leading to earthquakes, because rising pressure in this fluid weakens the rock” (Perry et al, 2011, p.8). Yet, since hydraulic fracturing does not exacerbate the severities of the earthquakes, it does not cause much concern in regards to human health.
Hydraulic fracturing uses large quantities of water, which would have to be treated in order to be used for other industrial purposes. Furthermore, the wastewater would unlikely be fit for human consumption, even after being treated. Fracturing fluids contain many toxic chemicals that can potentially migrate to underwater sources of drinking water. It is difficult to prove that hydraulic fracturing sites caused contaminations of local drinking wells for two reasons. Firstly, there is has been little research done to measuring the effects of hydraulic fracturing on pre and post drilling sites and their affect on local drinking water sources. And secondly, “…because groundwater supplies and natural gas deposits are often separated by thousands of feet of rock and earth, and groundwater can be contaminated by many sources, it is difficult to establish a definitive connection between drinking water and fracking.” (Manuel, May 2010, p.A199). It is an official stance that the EPA, “believes that… groundwater production, combined with the mitigating effects of dilution and dispersion, adsorption, and potentially biodegradation, minimize the possibility that chemicals included in the fracturing fluids would adversely affect USDWs [Underground Source of Drinking Water]” (EPA, June 2004, p. 7-3).
In regards to air pollution from hydraulic fracturing, little attention has been paid to the possible health effects of prolonged exposure to airborne fracturing fluid chemicals and exposure to VOCs from drilling sites. VOCs are contributors to ground ozone and are known to cause eye, skin, and respiratory complications. Yet, it is the American Petroleum Institutes stance that, “the sources of potential air emissions associated with hydraulic fracturing are temporary in nature. Hydraulic fracturing operations utilize large amounts of horsepower (hp), normally provided almost exclusively by diesel engines” (2011, p.16).
And as for induced seismic activity from hydraulic fracturing, “as seismologists and geologists across the country have already determined, the activity that occurs during the hydraulic fracturing process does not produce vibrations of noticeable size, and there is no evidence it causes earthquakes” (API, March 2012, p.4). Moreover, it is not the hydraulic fracturing that causes the earthquakes; it is the injection of wastewater pumped into disposal well that is more likely to induce earthquakes. Yet, as many hydraulic fracturing sites dispose of their water using disposal injection wells, it would be wise to conduct research on and to invest in other methods of product water disposal.
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Volz, C. D.; Michanowicz, D.; Christen, C.; Malone, S.; & Ferrer, K. (2010). Potential Shale Gas Extraction Air Pollution Impacts. How Organic Compounds Contained in the Shale Layer Can Volatilize Into Air, Become Hazardous Air Pollutants and Cause Ozone Formation. Center for Healthy Environments and Communities, University of Pittsburgh. Retrieved from: http://www.fractracker.org/2010/08/potential-shale-gas-extraction-air-pollution-impacts/