Environmental Dangers of Fracking

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A natural gas drill rig at night. Jon Mullen/E+/Getty

Natural gas drilling with high volume horizontal hydraulic fracturing (hereafter referred to as fracking) has exploded onto the energy scene in the last 5 or 6 years, and the promise of vast stores of natural gas under American soil has prompted a true natural gas rush. Once the technology was developed, new drill rigs appeared all over landscapes in Pennsylvania, Ohio, West Virginia, Texas, and Wyoming.

Many have worries about the environmental consequences of this new approach to drilling; here are some of those concerns.

Drill Cuttings

During the drilling process, large amounts of ground up rock, mixed with drilling mud and brine, are pulled out of the well and transported off the site. This waste then gets buried in landfills. Beside the large waste volume that needs to be accommodated, a concern with drill cuttings is the presence of naturally occurring radioactive materials in them. Radium and uranium can be found in drill cuttings (and produced water – see below) from a proportion of wells, and these elements eventually leach out of the landfills into the surrounding ground and surface waters.

Water Use

Once a well has been drilled, large amounts of water are pumped into the well at very high pressure to fracture the rock in which the natural gas is located. During a single fracking operation on a single well (wells can be fracked multiple times over their lifetime), on average 4 million gallons of water are used.

This water is pumped from streams or rivers and trucked to the site, bought from municipal water sources, or is reused from other fracking operation. Many are concerned about these important water withdrawals, and worried that it may lower the water table in some areas, leading to dry wells and degraded fish habitat.

Fracking Chemicals

A long, varying list of chemical additives is added to the water in the fracking process. The toxicity of these additives is variable, and many new chemical compounds are created during the fracking process as some of the added ingredients break-down. Once the fracking water returns to the surface, it needs to be treated before disposal (see Water Disposal below). The amount of chemicals added represents a very small fraction of the total volume of fracking water (around 1%). However, this very small fraction detracts from the fact that in absolute terms it is rather large volumes that are used. For a well requiring 4 million gallons of water, about 40,000 gallons of additives are pumped in. The greatest risks associated with these chemicals occur during their transportation, as tanker trucks must use the local roads to bring them to the drill pads. An accident involved spilled contents would have significant public safety and environmental consequences. 

Water Disposal

A large proportion of the prodigious amounts of water pumped down the well flows back up when the well starts producing natural gas. Besides the fracking chemicals, brine that was naturally present in the shale layer comes back up, too.

This amounts to a large volume of liquid that is released into a lined pond, then pumped into trucks and transported to either be recycled for other drilling operations, or to be treated. This “produced water” is toxic, containing fracking chemicals, high concentrations of salt, and sometimes radioactive materials like radium and uranium. Heavy metals from the shale are of concern too: produced water will contain lead, arsenic, barium, and strontium for example. Spills from failed retention ponds or botched transfers to trucks do happen and have an impact on local streams and wetlands. Then, the water disposal process is not trivial.

One method is injection wells. Waste water is injected into the ground at great depths under impermeable rock layers. The extremely high pressure used in this process is blamed for earthquake swarms in Texas, Oklahoma, and Ohio.

The second way fracking waste water can be disposed of is in industrial wastewater treatment plants. There have been problems with ineffective treatments at Pennsylvania municipal water treatment plants, so that practice has now ended and only approved industrial treatment plants can be used.

Casing Leaks

The deep wells used in horizontal hydrofracking are lined with steel casings. Sometimes these casings fail, allowing fracking chemicals, brines, or natural gas to escape into the shallower rock layers and severely contaminating ground water that may reach the surface of be used for drinking water. An example of this problem, documented by the Environmental Protection Agency, is the Pavillion (Wyoming) groundwater contamination case. 

Greenhouse Gases and Climate Change

Methane is a major component of natural gas, and a very powerful greenhouse gas. Methane can leak from damaged casings, well heads, or it may be vented during some phases of a fracking operation. Combined, these leaks have significant negative impacts on the climate.

Carbon dioxide emissions from burning natural gas are much lower, per quantity of energy produced, than from burning oil or coal. Natural gas would then seem to be a reasonably good alternative to more CO2 intensive fuels. The problem is that throughout the entire production cycle of natural gas, a great deal of methane is released, negating some or all of the climate change advantages natural gas seemed to have over coal. Ongoing research will hopefully provide answers as to which is least damaging, but there is no doubt that mining and burning natural gas produces great amounts of greenhouse gases and thus contributes to global climate change.

Habitat Fragmentation

Well pads, access roads, waste water ponds, and pipelines crisscross the landscape in natural gas producing regions. This fragments the landscape, reducing the size of wildlife habitat patches, isolating them from one another, and contributing to detrimental edge habitat.

Peripheral Aspects

Fracking for natural gas in horizontal wells is an expensive process that can only be done economically at high density, industrializing the landscape. Emissions and noise from diesel trucks and compressor stations have negative impacts on the local air quality and overall quality of life. Fracking requires large amounts of equipment and materials which themselves are mined or produced at high environmental costs, notably steel and frac sand.

Environmental Benefits?

  • At the local scale, the land footprint from fracking operations, especially once the well has been established and the drill rig is gone, is smaller than that of coal strip mines, mountain-top removal mines, or tar sands fields. The footprint of thousands of wells and pipeline right-of-ways over an entire region do add up, though.
  • Natural gas from Marcellus, Barnett, or other North American shale deposits allows us to rely on a domestic source of energy.  That means less energy spent transporting fossil fuels from overseas, and more importantly maintaining the ability to have stricter environmental controls over the entire energy production process.

Source

Duggan-Haas, D., R.M. Ross, and W.D. Allmon. 2013. The Science Beneath the Surface: A Very Short Guide to the Marcellus Shale.

Paleontological Research Institute.