Health and Safety Issues with Fracking

The hydraulic fracturing process used to acquire natural gas from underground rock formations like shale requires large scale industrial equipment and chemicals. This is necessary for drilling operations, fracturing solutions, and transportation of equipment, fluids, gas, and personnel. Despite a 30% increase in gas production in the last decade, the industrial process of natural gas extraction from Marcellus Shale formations via hydraulic fracturing generates a number of potential risks and hazards to human health and the environment.1-10

Chemical Use and Waste Generation

Chemicals Use with Fracking Fluids

Over 2,500 products containing 750 chemical compounds were used in hydraulic fracking fluids by 14 oil and gas companies between 2005 and 2009 alone. This amounted to the use of over 780 million gallons of hydraulic fracking fluid compounds in those four years alone. While many of the components are involved in a wide range of common products, there are still several that pose a serious risk to human and environmental health. The fracking fluid is mainly used to help fracture shale formations and provide openings for natural gas molecules to escape. The chemical fluids are also used to fight bacteria and corrosion of the well. The main types of chemicals used include acids, biocides, clay stabilizers, proppants, crosslinkers, corrosion inhibitors, gelling agents, friction reducers, surfactants, and iron controlling agents. While most oil and gas companies purchase their chemicals from vendors, some produce their own products to create their own special fracking fluid. Some of the most harmful chemicals used are displayed in the table right and many of them are carcinogens, Safe Drinking Water Act regulated chemicals, and hazardous air pollutants. Whether by air or water, all of these compounds pose a threat to the health and safety of people and the environment.

Chemical Components of Concern:

HVHF Waste Generation

Flowback Fluids

Within 2 weeks, rock deformation and release of pressure resulting from HVHF drives the release of hydraulic fracturing flowback fluids (HFFF), which consists of 10-70% of the original injected fluids during HVHF, to return to the surface along with the escaping hydrocarbons.2,17,18 The fluids and chemical additives used during the HVHF process causes the dissolution of shale constituents, such as organic matter, salts, heavy metals, and naturally occurring radioactive materials (NORMs), into the original injected solution. Because of this, flowback fluids return to the surface as a mixture of chemical additives and the naturally occurring dissolved substances.2,15,17,19-23 As the shale formation water continues to mix with injected fluids, the flowback fluids returning to the surface typically continue to rise in salinity.22

Produced Fluids

After the initial 2 week surge of HFFF, additional fluids, known as produced fluids, continue to migrate to the surface of the borehole throughout the life of the well.1,2 Produced fluid is the native groundwater present in the target formation that has been fractured during natural gas extraction.16,24 Hydrocarbons are extracted to the surface as a mixture of produced waters, gaseous or liquid hydrocarbons, chemical additives, and dissolved or suspended solids.24 During the production process, the gas is separated from the produced water. Produced fluids from this process contain low-molecular weight aromatic hydrocarbons like xylene, benzene, toluene, and ethylbenzene from both the target formation chemistry and chemical additives used during the extraction.22 Depending on the shale formation, produced fluids also have a high total dissolved solids (TDS) content that can range in salinity from below to over 7 times that of seawater.22 For example, the produced fluids from Marcellus Shale have been recorded to vary in TDS up to 180,000 ppm.22

Drilling Fluids

The process of drilling itself requires water and chemical additives to lubricate and cool the drilling equipment and clear drill cuttings, which generates “drilling fluid” waste.25 This drilling fluid often contains high suspended and total dissolved solids. As drilling and the technology associated with the gas extraction process continues to develop, the amount of drilling fluids used and waste generated will continue to rise.25

Dill Cuttings

Drill cuttings include any rock fragments or soil excavated by the drill bit to the surface before HVHF.10,26 Because drill cuttings are extracted before HVHF, they do not contain any chemical additives. However, the rock fragments or soil can contain components of the black shale such as pyrite, high salt content, heavy metals, and naturally occurring radioactive material (NORM).10 These naturally occurring components can potentially impact the surrounding environment. Pyrite, or iron disulfide (FeS2), in particular is problematic because it can oxidize to form sulfuric acid (H2SO4) and impact surface and groundwater with decreased pH and the release of metals from the soil.10

Waste Storage

waste water

Figure 9. 

Both HFFF and produced waters are typically stored temporarily on site in closed tanks or open impoundments (Figure 9).18,22,27 Impoundment storage can last weeks or several months before any treatment or reuse for further hydraulic fracturing. These wastewater impoundments are large artificially created ponds designed to evaporate the water via solar radiation as well as prevent downward migration of wastewater or subsurface infiltration into groundwater.28 This strategy for wastewater management has become popular amidst restricted options for waste disposal like deep well injection sites and technical treatment limitations.18 Storage and transportation of these waste fluids from production sites may increase the potential for leaks and spills, which can impact the surrounding land and surface and ground waters.29 Because of the dangers posed by the chemical nature of the fluids, much of the waste is disposed of in deep wastewater injection wells.2,20

Waste Disposal

While most of the wastewater (95%) associated with gas drilling in the U.S. is disposed of via deep well injection sites, the natural geology makes this disposal method unsuitable in the Marcellus Shale region.20,25 Because of this, other methods of waste management have been used that include (1) partial wastewater treatment and recycling for further use in hydraulic fracturing, (2) the use of private industrial wastewater facilities to treat and reuse effluent or discharge treated materials into waterways, (3) utilizing municipal wastewater treatment facilities and subsequent discharge into local waterways, and (4) transporting wastewater to areas where the capacity for deep well underground injection exists.25 Because municipal waste treatment facilities are generally not equipped for treating such high TDS concentrations in hydraulic fracturing wastewater, a mandate by the PADEP in 2008 limited the amount of wastewater being sent to these facilities by Marcellus drilling. Industrial treatment facilities have methods to flocculate suspended solids or precipitate metals in Marcellus wastewater, but few possess the technology to remove many of the ions associated with high TDS load of the wastewater. As a result of prior waste disposal via industrial treatment facilities and subsequent discharging into local waterways like the Monongahela River, new effluent standards based on limiting TDS more strictly [Pa. Code § 95.10., 2010] were implemented by Pennsylvanian legislature.25 With unconventional wastewater volumes increasing annually and limitations on the use of municipal and industrial waste treatment facilities, the focus for disposal switched to deep well injection sites in 2011.

Deep Well Injection Sites

Most of the produced water collected happens in a short time after initial gas retrieval. However, waste water will still be collected in small amounts over time as gas is continuously pumped out of the shale formation. While there is an effort to try and recycle some of the produced water for fracking other wells, most is disposed of at deep well injection sites (class II underground injection wells). Class II wells are used for storing oil and gas production brine, hydrocarbons, and other fluids. Waste is pumped into rock layers far below underground aquifer systems to ensure the safety of groundwater. There are currently seven injection sites for oil and gas waste in PA and they are regulated by the Environmental Protection Agency's Underground Injection Control Program (UIC) via Safe Drinking Water Act (SDWA).

Air Pollution

When hydraulic fracturing first began in PA, the first major concerns involved water safety and the issue of hazardous chemicals injected underground. Perhaps more importantly, the air we breath can also be impacted by hydraulic fracturing drilling operations. Invisible to the naked eye, volatile organic compounds involved in fracking water can evaporate into the air and cause harm to human health and help produce ground-level ozone. Particulate matter can be produced from construction, drilling, and transportation operations and swept up by wind and weather to urban areas, and leaking methane from extraction and transportation has stirred recent concern for methane's serious impact on climate change as a greenhouse gas.

Volatile Organic Compounds

Volatile organic compounds (VOCs) can easily evaporate from liquid into the air we breathe. These compounds can mix with nitrogen oxides (NOx) to produce ground-level ozone (O3), which is the primary component of smog (see figure right). Excessive exposure to VOCs is chronically toxic. Health related symptoms will take time to develop and this can include kidney, liver, and nervous system failure, and some of them are also carcinogenic. The major cause for VOC emissions during fracking involves the construction of large produced water ponds mentioned above. These ponds hold millions of gallons of waste water and contain large concentrations of VOCs, which are free to evaporate naturally into the air unregulated. The ground-level ozone produced from VOCs and nitrogen oxides presents even more health problems. These can vary from short term throat irritation, coughing, congestion, and chest pain to long term exposure issues like asthma, bronchitis, and emphysema. Ground-level ozone has also been known to reduce lung function.

Particulate Matter

Particulate matter includes very small solid or liquid particles (10 µm) produced by emissions or stirring up dirt and dust. Some major causes of particulate matter pollution from fracking include:

  • Diesel engines
  • Flaring
  • Heavy truck traffic

These tiny particles can have serious impacts on human health if breathed frequently. Once particulate matter enters the bloodstream through the lungs, it has access to our major organs. Some of the largest health related issues are decreased lung function, heart attacks, irregular heartbeat, and aggravated asthma. Because particulate matter can be carried by wind and precipitation, people can be affected miles from a drilling site.

Greenhouse Gases

The greenhouse effect is the process by which atmospheric greenhouse gases absorb and re-radiate infrared radiation originating from the sun (see figure right). This process is responsible for regulating planetary temperatures. Such greenhouse gases (GHGs) like CO2, CH4, and N2O can trap heat in the lower atmosphere by re-radiating the infrared radiation back towards the surface of the planet. This increases the average surface temperature and has an impact on the world's ecosystems and climate.

Some of the major sources of CO2 include burning fossil fuels, cement production furnaces, and the burning of forests and grasslands. About 3 billion tons of CO2 is taken up by terrestrial ecosystems and about 2 billion tons are absorbed by the oceans, leaving an annual atmospheric release of about 4 billion tons of CO2 per year. Natural gas, or CH4, is less abundant than carbon dioxide but it absorbs 23 times as much infrared energy per molecule. Methane is produced anywhere organic matter decays without oxygen, especially underwater. Some sources include ruminant animals, wet-rice paddies, coal mines, landfills, wetlands, and leaking pipelines. Nitrous Oxide (N2O) is produced mainly by chemical reactions between atmospheric nitrogen and oxygen, which combine in the presence of heat from internal combustion engines.

Methane (CH4) is more efficient at trapping radiation than CO2 and according to the EPA, pound for pound, CH4 impacts climate change twenty times greater than that of CO2 over a one hundred year period. So methane does burn cleaner than coal in the terms of producing less CO2, but on its own, methane is a greater threat to climate change than CO2 due to its large contribution to the greenhouse gas footprint. Because of this, there have been a lot of recent studies on methane releases from drilling and transportation operations.