Is the water safe? A recent study by Duke University produced mixed results.
The study found that hydraulic fracturing does not cause the pathways in rock formations that allow salinated water into shallow aquifers. According to the study, the pathways are naturally occurring.
But that isn’t necessarily good news. Although these pathways aren’t necessarily caused by Marcellus Shale drilling, they can still transport chemicals and other contaminants into the drinking water supply. The naturally occurring pathways can allow gases and Marcellus brine to migrate up into shallow groundwater aquifers from deeper underground shale gas deposits. This situation was found, according to the study, in the the geochemical fingerprint of the salinity detected in well water from the Lock Haven, Alluvium and Catskill aquifers suggesting that a network of natural pathways exist in some locations, especially in valleys.
“This could mean that some drinking water supplies in northeastern Pennsylvania are at increased risk for contamination, particularly from fugitive gases that leak from shale gas well casings,” said Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment.
Vengosh said that although the results of this study show that the saline water wasn’t derived from gas drilling during the study, the results are only part of an understanding of what is going on. He said the results do not apply to all of Pennsylvania or all areas of the Appalachian Basin and that the study needs to be duplicated.
The Duke team evaluated 426 samples from groundwater aquifers in six counties overlying the Marcellus Shale formation in northeastern Pennsylvania. The study appears this week in the online early edition of the Proceedings of the National Academy of Sciences. It was funded by Duke’s Nicholas School of the Environment.
“The small group of homes whose water we sampled may be at higher risk of contamination due to underlying geology,” said Nathaniel Warner, a PhD student at Duke who was lead author on the study. “By identifying the geochemical fingerprint of Marcellus brine, we can now more easily identify where these locations are and who these homeowners might be.”