Earlier this week PNAS published a study that documents a link between hydraulic fracturing and water contamination. A team of Duke researchers showed that water wells located close to active drilling sites had methane levels 17 times higher than water wells located further away. Their definition of active drill site: within 3280 feet of a well.
The scientists tested 68 drinking water wells in the Marcellus and Utica shale drilling areas in northeastern Pennsylvania and southern New York State. They measured dissolved salts and other constituents (carbon, boron and radium) as well as methane levels.
The average methane concentration in drinking water was high enough – over 28 milligrams per liter (mg/L) – to qualify for hazard mitigation as recommended by the US Office of the Interior. But some water had much more methane – up to 64 mg/L.
Though the researchers did not find evidence of fracking chemicals in the water wells, they expressed concern for that they see is a clear correlation between drilling activity and methane migration into drinking water. The presence of methane demonstrates that pathways do exist for migration of other potential contaminants.
Even more interesting were the recommendations they made in a White Paper accompanying their study.
Research recommendations:
- Initiate a medical review of the health effects of methane.
- Create a national database listing methane, ethane and propane concentrations in drinking water.
- Find out how methane is getting into drinking water, say the scientists. Is methane contamination due to poorly constructed well casings? Or is the process of fracking creating pathways for methane and other chemicals to migrate to the surface?
- Develop better estimates for greenhouse gas emissions of methane associated with shale gas extraction.
- Conduct extensive baseline water testing prior to exploration and drilling. They recommend testing water at least 3,000 feet from well sites and that testing be conducted by independent state-certified labs.
- Better study of waste treatment. For drilling fluids going to wastewater treatment facility, regulators need to understand how much of the chemicals are removed in the waste treatment plants and what are the long-term ecological effects downstream.
Policy recommendations:
- Regulate fracking under the Safe Drinking Water Act (SDWA).
- Fully disclose chemicals used in hydro-fracking.
Scientists found an association between methane and fracking, but that's not the same as causation.
ReplyDeleteThe 'null hypothesis' would be that something else causes both, and there are plenty of candidates. E.g. areas with fault lines and fractures are often drilled, because gas concentrates there (and flows quickly). But, that's geology where methane can also rise easily out of deep formations, and into aquifers.
Without 'before and after' testing of wells, you really can't conclude much. I've personally visited two houses (in Albany and central PA) with well water that contained so much methane that the entertaining thing to do at parties was to stand around the kitchen sink with matches, making explosions. There's lots of methane underground, and it does get into aquifers on its own.
Selection bias is also a potential problem-- the paper doesn't talk about how wells were chosen. About 10 of the 26 water wells near gas wells were in Dimock, which has been in the news. Did the researchers solicit volunteers? That could easily skew the results.
However, the white paper is correct-- more research is needed.
And, most scientists cringe when their research hits the popular press, since it's easy for writers to jump to conclusions, see what they want to see, etc.
The Duke study did not find traces of fracing fluids because they did not analyse for a single fracing chemical. Instead they did analyse for Na and Cl. Low concentrations of both lead them to conclude that the gas contamination was not accompanied by contamination from saline formation waters or "saline fracturing fluids". However fracing fluids are not saline. Chemicals compose only 0.05% and little if any of that is salt.
ReplyDeleteI'm really starting to wonder why no one seems to actually read the Duke paper.
ReplyDelete"Scientists Show Fracking Contaminates Drinking Water"
The study absolutely does not say that. This is completely false.
"Earlier this week PNAS published a study that documents a link between hydraulic fracturing and water contamination."
The study does not say this either. This, too is a totally false statement.
The paper was unable to establish or eliminate any cause for the sample values they found. They state that expressly here:
"More research is needed across this and other regions to determine the mechanism(s) controlling the higher methane concentrations we observed."
In addition Dr. Jackson has said repeatedly in the press that he does not believe hydraulic fracturing to be the cause of the values found in these samples.
Actually, when you READ the study you see that they Really Do indeed say that there is a link. They also say that in their white paper. They do not say "cause" - they do say that when wells are fracked near drinking water wells, there IS more methane migration.
ReplyDeleteInterpret that as you will, chris...
Oh, and take another look at those very good graphs.
The paper authors propose a link between methane in the water and the proximity to "wells." They did not have any baseline data to show that the gas was not already in the water before the (relatively recent) Marcellus drilling (and fracturing) activity took place. There are previously drilled oil and gas wells (1950s and 1970s) in the area and there are also natural fracture pathways for methane to enter the water zones ... as well as evidence that methane in drinking water wells has been a problem for a long time prior to the recent drilling activity. There is not enough information to show that the methane in the water was related to either the Marcellus well drilling or fracturing. It is still possible that either might be a reason, but much, much more likely that it might be the drilling process than the fracturing process. Until a study with baseline data is done, no one will know. Penn State is doing such a study in northwestern PA and will publish it later this year.
ReplyDelete