shdoherty

What Do They Do With the Waste?

May 4, 2016 by shdoherty Leave a Comment

Around 10 to 30% (and up to 60%) of the water that is initially injected into the ground during the fracking process returns to the surface with the extracted gas. This water is referred to as “flowback” and is likely to contain naturally occurring elements such as salts and heavy metals, from the ground, and can contain trace amounts of the chemicals from the fracking fluid.

This water must be treated to avoid environmental repercussions. Particularily serious problems arise when companies try to cut expenses and do not treat their water and dispose of it improperly. The wastewater that is treated is typically either treated on site and used for injection into another well or can be hauled off for treatment to be added back to surface water. Since total dissolved solids (TDS) have been found to negatively impact aquatic ecosystems, the Pennsylvania Department of Environmental Protection (DEP) currently requires that the flowback be treated until it has a TDS concentration of 500 parts per million or less before the water can be mixed with other surface water.

Because there are such large volumes of water used for each frack, there can be up to 1.5 million gallons of resulting flowback. Because these volumes of wastewater are so large, it makes it increasingly more likely for a spill to occur. Wastewater can spill on site by leaking out of storage containers or when adding/extracting the liquid from the storage containers. Additionally spills can occur when the fluid is being transported to an alternate site for treatment. Because the wastewater is incredibly salty and contains various chemicals it is likely to have detrimental effects on the ground to which it is exposed. Even in the best case scenario it has been predicted that each individual well in the Marcellus Shale region is likely to release at least 200 m3 of contaminated fluids. Figure 2 summarizes the ways fracking can lead to water pollution.

(please click on image to read)

Sources:

http://www.nature.com/nature/journal/v477/n7364/abs/477271a.html

Image:

©S. Doherty 2016

What’s up with Fracking Fluid?

May 4, 2016 by shdoherty Leave a Comment

So what exactly is the fluid injected into these wells composed of? Fracking fluid is roughly 90% water, 9.5% sand and 0.5% chemical additives. These chemicals are added to prevent erosion of metal pipes, reduce friction, maintain fluid viscosity and stop microorganisms from growing within the pipes. The sand is added to hold fractures open. But when considering the large volumes of water used within fracking jobs it is important to note that this seemingly tiny 0.5 percentage can equate to 80-300 tons of chemicals per frack.

The “cocktail” of chemicals added varies from site to site but there are roughly 600 chemicals used worldwide and approximately 50 used in the Marcellus Shale region. Just some of the chemicals used and their purpose are outlined in the image below:

These chemicals include some volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene along with organic acids, hydrogen sulfide and various naturally occurring radioactive elements such as radium and uranium. Long term exposure to chemicals such as VOCs can lead to an increased risk of cancer, liver damage, kidney damage and central nervous system damage.

Why does it matter that these chemicals are used in fracking? In order to get to the Marcellus Shale rock formation workers must drill through an aquifer. This aquifer is an important source of groundwater for the region and supplies a large portion of water to the local towns. In order to drill through the aquifer workers are required to build a well casing to prevent the flow of fracking fluid and natural gases to the surrounding groundwater. A well casing is made by inserting a steel pipe into a borehole and cementing it into place. Leaks/short cuts taken in building these well casings may enable fracking fluid and natural gases to leak out of the pipes and contaminate these aquifers and consequently pollute local water supplies.

Sources:

http://www.nature.com/nature/journal/v477/n7364/abs/477271a.html

https://www.epa.gov/hydraulicfracturing

http://www.health.state.mn.us/divs/eh/indoorair/voc/

Methane in the Water?

April 12, 2016 by shdoherty Leave a Comment

So why has fracking been met with so much opposition? For one, citizens in towns where fracking is actually taking place have been scared by reports of methane contaminations in their water supplies. Though it is hard to conclusively determine the root cause of these methane leaks, fracking could provide a potential explanation.

Many fracking sites, including the Marcellus Shale region, lie under watersheds which are used to supply drinking water to local towns. In order to reach this region, workers build casings around the regions they drill to reach the natural gas deposits. Drilling through this aquifer region is clearly outlined in the image below:

Problems arise when these casings are not sealed properly. Holes within these seals enable gases to leak out and may explain the methane contamination of within local water supplies.

An initial study in 2011 looked at methane concentrations in 68 drinking water wells at varying distances from fracking sites in the Marcellus Shale region. They found that “methane contamination rose sharply with proximity to natural gas drilling and hydraulic fracturing.” Interestingly, however, when this type of study was repeated in 2015 in 11,309 drinking water wells within the same region, there was found to be no significant differences in methane concentrations based on proximity to the tracking site. Conflicting studies such as these two are continuing to surface making it difficult for scientists to develop a firm stance on fracking’s impact on local water supplies.

Sources:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866701/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222989/

http://www.sciencemag.org/news/2015/03/methane-drinking-water-unrelated-fracking-study-suggests

Sheer Volume

March 10, 2016 by shdoherty Leave a Comment

One large concern regarding fracking is the enormous amount of water required to carry out the process. Typically 90% of the liquid injected into the well is water. Each well can use up to 144 million gallons of water. An important fact to emphasize is that, on average, only 5% of the water originally injected into the well is reused. Why should we care about this? Consider a typical family of four in Pennsylvania. They will use approximately 300 gallons of water a day. An average well requires around 5.6 million gallons of water per frack. Therefore, the water used in just one frack would provide that household with water for 51 years. The magnitude of the volume of water used during fracking is further emphasized in the info graphic below:

The amount of water used within fracking can also have an influence on the quality of water. This can happen when more ground water is removed than can be replenished. This may allow contaminants to mobilize and additionally allow for lower quality water to move in. This is especially important since this is a large source of our drinking water. The extensive amount of fracking occurring within the Marcellus region may eventually have an impact on the resident’s water supply and the quality of the water there.

Sources:

https://cfpub.epa.gov/ncea/hfstudy/recordisplay.cfm?deid=244651

http://www.theoec.org/campaign/fracking-impacts-water-quality

What Do They Do With the Waste?

What’s up with Fracking Fluid?

Methane in the Water?

Sheer Volume

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