October 7, 2013 | 9
This weekend I spoke with Dr. Avner Vengosh, one of the researchers from Duke University that published results of a study looking at wastewater quality from “fracking” operations in Pennsylvania. Their study, “Impacts of Shale Gas Wastewater Disposal on Water Quality in Western Pennsylvania”, was published this month in the journal Environmental Science & Technology.
The study was widely covered in the news and on various blogs, but there are some nuances that deserve a little more attention. The summary from Bloomberg:
Naturally occurring radiation brought to the surface by gas drillers has been detected in a Pennsylvania creek that flows into the Allegheny River, illustrating the risks of wastewater disposal from the boom in hydraulic fracturing.
Sediment in Blacklick Creek contained radium in concentrations 200 times above normal, or background levels, according to the study, published today in the journal Environmental Science and Technology. The radium, along with salts such as bromide, came from the Josephine Brine Treatment Facility about 45 miles (72 kilometers) east of Pittsburgh, a plant that treats wastewater from oil and gas drilling.
After reading the paper, I came away with three big takeaways:
The paper recommends advanced treatment technologies to “prevent discharge of contaminants (Ra and Br) to the environment in areas of shale gas development and hydraulic fracturing”. Dr. Vengosh elaborated (via email):
Our data show that halogens (chloride and bromide are not removed at all) and Ra was removed but not entirely. Removal of halogens would require different treatment technology, such as desalination. The technologies to treat such high level of salinity and radioactivity complex water do exist, the questions are the cost, implementation, and monitoring.
I asked Dr. Vengosh if industrial discharge limits should be revised to anticipate mixing and sedimentation. Here is his answer:
Yes! In our previous study on the impact of effluents from coal ash ponds in NC (Ruhl et al., 2012, see attached) we showed that arsenic is attached to particulate matter and redissolved under reducing conditions at the lake bottom sediments. Thus in spite of the relatively low content of As [arsenic] and Ra [radium] in the effluents their accumulation in river or lake sediments could cause a long-term environmental hazard.
A follow up question from me: “is this unique to this type of stream? Or put another way, with different stream and flow conditions, would the amount of accumulated Ra to be lower and within regulations?”. His reply:
I do not think so, we have results from a pond (not published yet) with similar Ra accumulation results. So radium (and other toxic metals like arsenic in oxic conditions) would tend to be attached to any suspended matter or sediments. The rate of the stream flow might cause a larger and perhaps more diluted zone of Ra accumulation, but the same process is expected.
The major impacts of radium accumulation appear to be localized to less than 200 meters downstream from the treatment facility, and not traveling in significant concentrations downstream and into other watersheds. However, significant amounts of shale-related water is sent through centralized waste treatment facilities and discharged to local streams.
These results indicate how quickly the industry has moved relative to the regulatory and scientific communities and the need for stricter regulations based on scientific data. Increased water reuse (or waterless fracking) would address this issue (previous research estimates that 70% of flowback and produced fluids are currently reused in the Marcellus Shale region) as would revised effluent limits for salinity, toxic metals, and naturally occurring radioactive materials.
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