Yanna Lee

A new Yale study may shift perceptions about the dangers of hydraulic fracturing, the natural gas extraction process commonly known as fracking.

For over two years, a team of researchers from the Yale Chemical and Environmental Engineering Department took samples from groundwater aquifers in northeastern Pennsylvania, where drilling companies use fracking to extract natural gas from the Marcellus Shale, a layer of sedimentary rock thousands of feet below the ground. Fracking companies inject fluid containing over 900 chemicals into the shale layer, making many people concerned that these chemicals will seep into groundwater aquifers, a source of drinking water. The study, published Oct. 27 in the Proceedings of the National Academy of Sciences, shows that aboveground fracking practices may actually pose a greater threat than belowground activities.

“When most people say fracking or hydraulic fracturing, they’re thinking of … the injection of fluids into the ground to crack open rock and release these gas molecules,” said Brian Drollette GRD ’20, a chemical and environmental engineering Ph.D. candidate and the lead author of the study. “[But] it’s not the actual hydraulic fracturing itself that’s causing the groundwater contamination. It’s the overarching operations that are going on at the ground surface that’s probably impacting the groundwater.”

This study analyzed high molecular weight organic compounds used in fracking fluids, including a group of toxic compounds known as BTEX: benzene, toluene, ethylbenzene and xylene.

Two main pieces of evidence suggested that these organic compounds in the groundwater came from the surface of the earth. On one hand, the level of helium present in the groundwater more closely matches the level of helium present in water at the surface. Also, the abundance of these organic compounds in groundwater correlates to the distance of the nearest surface spill.

Furthermore, the low level of salt in the groundwater does not match the high salt content of water from the shale layer, suggesting that fracking fluids have not moved from the shale layer to the groundwater aquifers. The shale layer is in some places thousands of feet below the aquifers.

“I think it changes concerns and highlights some new ones, perhaps,” said Desirée Plata, professor of chemical and environmental engineering and principal investigator and co-author of the study. “What’s encouraging about this study is that if you do have a contamination event, usually it’s something you’ve known about. It happened at the surface … [And] the compounds we found are really treatable … You can warn people in the area to start treating their water.”

The concentration of organic compounds present in the groundwater sampled in this study was so small that the water did not violate the drinking standards set by the Environmental Protection Agency, according to the study authors.

David Brown, director of public health toxicology for the nonprofit Environment and Human Health, Inc., said no improvements to the study could be made.

“It’s a superb study,” Brown said. “Do I think any improvement could be made in Pennsylvania drilling? Yeah. Given the findings [of this study], it’s likely that the state agencies don’t have enough resources or technical expertise to monitor the [fracking] well … That’s the real message out of this paper.”

Drollette said that, in the future, research can be done to examine the fate of chemicals injected into the ground for fracking. The shale layer has a large amount of heat and pressure because it is deep underground, so the layer becomes a “reaction vessel” for chemical transformations, he added.

Plata suggested that testing be conducted in other areas of the country where fracking occurs. Different subsurface geology can lead to different amounts of “communication,” or permeability, between the shale layer and groundwater aquifers. Plata also noted that, over time, fracking will change the degree of permeability.

“When you perform hydraulic fracturing activity, you’re changing the subsurface inherently,” Plata said. “So the question is, just because we didn’t see [the movement from the shale layer to the groundwater aquifers this time], does that mean that it won’t happen in the future?”

Spills that occur at fracking sites above the Marcellus Shale are reported to the Pennsylvania Department of Environmental Protection.

  • Hope Forpeace

    Methane migration is the main culprit in contamination cases in Pennsylvania. As far as I can see, this study did not test for methane.

    A major study from Texas is also important to consider: The UT Arlington team tested 550 water samples collected from public and private water wells in North Texas’ Barnett Shale region over the past three years. It found elevated levels of 10 different metals as well as the presence of 19 different chemicals compounds including so-called BTEX (benzene, toluene, ethyl benzene and xylenes) compounds associated with hydraulic fracturing. The study also found elevated levels of methanol and ethanol.
    Read more at: http://phys.org/news/2015-06-barnett-shale-area-elevated-contaminants.html#jCp

    • FrackmanGasser

      Methane migration is well-known to occur naturally in northeast PA, and has for years – look at Salt Springs State Park, where there is a flaming fountain from naturally occurring methane migration into groundwater. PA has among the weakest standards for residential water well drilling. Many residents in NY had their water tested prior to expected drilling and were surprised to find elevated levels of methane. Without baseline testing you cannot assume anything. As to the study you cite, I see nothing in there that indicates there was any baseline testing performed, and I would be surprised if there were. Even the authors caution that their data does not necessarily identify drilling and fracking to be causative.

      “These data do not
      necessarily identify UOG (unconventional oil and gas) activities as the
      source of contamination; however, they do provide a strong impetus for
      further monitoring and analysis of groundwater quality in this region as
      many of the compounds we detected are known to be associated with UOG
      techniques.”

      Read more at: http://phys.org/news/2015-06-barnett-shale-area-elevated-contaminants.html#jCp
      “These data do not
      necessarily identify UOG (unconventional oil and gas) activities as the
      source of contamination; however, they do provide a strong impetus for
      further monitoring and analysis of groundwater quality in this region as
      many of the compounds we detected are known to be associated with UOG
      techniques.”

      Read more at: http://phys.org/news/2015-06-barnett-shale-area-elevated-contaminants.html#jCp
      “These data do not
      necessarily identify UOG (unconventional oil and gas) activities as the
      source of contamination; however, they do provide a strong impetus for
      further monitoring and analysis of groundwater quality in this region as
      many of the compounds we detected are known to be associated with UOG
      techniques.”

      Read more at: http://phys.org/news/2015-06-barnett-shale-area-elevated-contaminants.html#jCp
      “These data do not
      necessarily identify UOG (unconventional oil and gas) activities as the
      source of contamination; however, they do provide a strong impetus for
      further monitoring and analysis of groundwater quality in this region as
      many of the compounds we detected are known to be associated with UOG
      techniques.”

      Read more at: http://phys.org/news/2015-06-barnett-shale-area-elevated-contaminants.html#jCp

      • https://www.facebook.com/app_scoped_user_id/YXNpZADpBWEgwdW10RHBsWHFsQl96T043RVhyZAzV0MXdBbUhfT2o3WE1ldHp2UktjQVV2RU5Eb0xsQnRrV21TYmFSendGTVZAZAbzFLei1wSENPS0VsXzFGalZA2ZAkhOLXFSMXZAzUW1URUp4/ Scott Cannon

        Sorry, I can’t take an anonymous troll with a picture and name like yours seriously. Gather some courage and post this information with your real name.

    • The-Toad

      How much of the Yale endowment is in fossil fuels?

      • Hope Forpeace

        I don’t know – but Big Oil has been fairly successful at purchasing our most respected universities.

  • scottvideo

    Want to see how unscrupulous industry and politicians use this information to spin the truth to get gullible people to believe there are no dangers? Watch Congressman Tom Marino from PA say there is not one single case of contamination from fracking. We know that other steps in the fracking process contaminate ground water, but not mentioning that is lying by omission. Shame on the Congressman. We deserve better representation that isn’t on the take from gas campaign funding. https://youtu.be/dm6QgaFXxn0

  • tke265

    Hope For Islamic Rule aka HFP is not honest and never was

  • ShadrachSmith

    Fracking is good because plentiful energy is the condition precedent to a decent urban life.

    Carbon fuels are not bad. That is just a DNC meme to gain bureaucratic control of the nation’s energy use. The earth is not warming, and the greatest threat to civilization remains unleashed bureaucrats.

  • Ray Kinney

    Does fracking practice involve contracting with other industrial companies to dispose of their chemical waste by deep injection, as was done for years by fertilizer companies spreading ‘soil amendment’ toxic waste onto good cropland?