Behind the headlines: Fracking and water contamination
There are fears that hydraulic fracturing used to extract shale gas could be behind water contamination in the US. These fears have been a touchstone of anti-fracking protests around the world.
New research that’s attracted a lot of media interest today seems to put paid to those concerns, finding faulty well casings are to blame instead.
But depending on which headline you read, you might have come away with a different impression. So what’s really going on?
Contradictory coverage
The new study looked at drinking water samples from 133 wells in the Marcellus and Barnett shale areas of the US. The researchers wanted to know why these wells contained higher than usual levels of hydrocarbons like methane. Was the contamination caused by nearby fracking or was it naturally present in the water?
UK newspaper headlines convey some apparently contradictory messages about the study’s findings. The Times leads with “Fracking not guilty of water contamination”. In contrast, The Guardian goes for “Drinking water contaminated by shale gas boom in Texas and Pennsylvania”.
Both headlines are accurate, if rather incomplete. As The Times says, the new research found the fracking procedure was not to blame for water contamination. But as The Guardian points out, the study did confirm that some peoples’ water had been contaminated by shale gas extraction activities, if not the process of drilling itself.
Extracting shale gas involves drilling deep underground through a vertical well that is later lined with a concrete casing. At depths of hundreds or even thousands of metres, horizontal wells are drilled sideways off into shale rock that is split apart using pressurised water and sand.
The researchers checked the spread of different chemical isotopes in the drinking water samples. This showed that there was no migration of methane or other contaminants from the deep horizontal fracked wells into peoples’ drinking water.
Fingerprints of contamination
But they used the same technique to show the chemical fingerprint of methane contamination from the vertical wells in nearby drinking water. That’s significant because until now, the evidence around fracking and water contamination has been inconclusive and contested.
The new research provides much stronger evidence that shale gas extraction can contaminate water supplies, if concrete well casings crack or leak due to poor construction or design. This vindicates the 2012 Royal Society inquiry into fracking safety, which placed great emphasis on well integrity.
Some papers’ headlines managed to convey the complexity of the new research findings more fully than The Times or The Guardian . The Telegraph, for instance, said “Fracking doesn’t contaminate water supplies, faulty shale gas wells do”.
The Associated Press story on the research explains why it provides a mixture of good and bad news.
Study co-author Robert Jackson of Stanford University told AP:
“I don’t think homeowners care what step in the process the water contamination comes from. They just care that their lives have changed because drilling has moved next door.”
But study lead author Thomas Darrah of Ohio State University told AP the findings were good news because well integrity problems are easier to fix and more preventable than problems associated with very deep horizontal drilling.
What it means for the UK
Ken Cronin, chief executive of industry body the UK Onshore Operators Group told Carbon Brief the findings confirmed that well integrity was of the highest priority.
Cronin says:
“In the UK, aquifers are protected by a minimum of three layers of steel casing and cement. These casings are pressure tested before any operation is allowed to commence and they must be inspected by an independent well examiner.”
The government’s Health and Safety Executive says it will insist on high standards of well casing construction so that the risk of contamination is minimised. An Environment Agency review of well integrity best practice argues these standards will “provide a very high degree of environmental protection”.
There will also be baseline monitoring to check methane levels in drinking water before drilling starts and ongoing environmental monitoring requirements imposed by the Environment Agency. This should make it easier to keep tabs on any fracking water contamination if it develops.
In short, the evidence of water contamination risks associated with fracking is now stronger than ever. UK regulators say they’re on the case, with only one exploratory fracking well having been drilled so far. If a shale gas industry takes off in the UK, only time will tell if regulators’ hopes for risk-free fracking are matched by reality.