Pennsylvania researchers have corrected a recent study that suggested increased bromide levels in private water wells after drilling or hydraulic fracturing occurred nearby.
The October 2011 report from the bipartisan Center for Rural Pennsylvania, an agency of the Pennsylvania General Assembly, initially found increased bromide levels in seven of the 233 water wells tested before and after natural gas activities took place nearby, but researchers are now reducing that finding to a single case (see Shale Daily, Oct. 28).
"The researchers now advise that the bromide concentration data were incorrect due to a lab error from the subcontracted, state-accredited water testing laboratory. The laboratory has since provided a data update," the authors wrote in an error notice last week.
The Pennsylvania State University researchers responsible for the results said the single case of increased bromide levels also showed increase levels of chloride, hardness and "other indicators after drilling and fracking had occurred, as documented in the report."
The Center for Rural Pennsylvania plans to revise the report in the coming weeks, it said.
The researchers originally said the bromide findings suggested "more subtle impacts to groundwater and the need for more research." And because the cases were mostly within 3,000 feet of development, the report also suggested the need for increased setbacks. The Pennsylvania General Assembly is reviewing legislation that would increase setbacks from current levels but has yet to decide on the new distance.
There is no federal drinking water standard for bromide because the compound only becomes significantly toxic to humans when mixed with certain other compounds.
The original study drew attention for finding methane contamination in 20% of private water wells tested in rural Pennsylvania before Marcellus Shale operations began nearby, challenging a Duke University report that found a correlation between methane levels of in water wells and hydraulic fracturing, a report that drew heavy criticism from the Pennsylvania Department of Environmental Protection (see Shale Daily, June 8; May 11).