Texas Study Shows Water Pollution Near Gas Drilling
26 July 2013
By Ken Ward Jr.
CHARLESTON, W.Va. -- A new study by researchers in Texas has
documented high levels of metals in drinking water supplies near
natural gas production sites, a finding they say shows the need
for more research into the impacts of the nation's gas-drilling
Elevated concentrations of arsenic, selenium and strontium were
discovered in drinking water wells located closest to natural gas
extraction sites, according to the study, by a team of scientists
from the University of Texas at Arlington.
Researchers did not pinpoint the exact source of the
contamination, and said their findings were not strong enough to
suggest "systematic contamination of groundwater" by the natural
"We suggest that episodic contamination by private water wells
could be due to a variety of natural and anthropogenic factors
such as the mobilization of naturally occurring constituents into
private wells through mechanical disturbances caused by intense
drilling activity, reduction of the water table from drought or
groundwater withdrawals, and faulty drilling equipment and well
casings," said the study, published online Thursday by the journal
Environmental Science and Technology.
The study is latest in a series of scientific assessments that are
just beginning to examine the potential water quality impacts of a
nationwide natural gas boom driven by technological advances in
hydraulic fracturing and horizontal drilling.
"This study alone can't conclusively identify the exact causes of
elevated levels of contaminants in areas near natural gas
drilling, but it does provide a powerful argument for continued
research," said lead author Brian Fontenot, a UT Arlington
graduate who now works for the U.S. Environmental Protection
The effort focused on water quality in the Barnett Shale, a
gas-rich geologic formation that underlies a 5,000-square-mile
area in 17 counties of north Texas.
Researchers sampled 100 water wells from the Trinity and Woodbine
aquifers, overlying the Barnett Shale and, as "reference sites"
from the Nacatoch aquifer east of the Barnett Shale.
One piece of potential good news was that the study detected none
of the family of BTEX chemicals - benzene, toluene, ethylbenzene
and zylenes - in the drinking water, a possible indication that
chemicals used in the hydraulic fracturing, or "fracking" process
had not migrated into the water wells.
But, researchers detected the highest levels of metal contaminants
within 3 kilometers of natural gas wells, including several
samples that had arsenic and selenium above concentrations
considered safe by EPA. Areas lying outside of active drilling
areas or outside the Barnett Shale did not contain the same
elevated levels for most of the metals.
"At minimum, these data suggest that private wells located over
natural gas wells may be a higher risk for elevated levels of
constituents than those located further from natural gas wells,"
the study concluded.
Duke University scientist Robert Jackson, who has done some widely
cited work on gas drilling impacts, said one limitation of the new
Texas study was its small number of "reference" sites - just nine,
with five outside the Barnett Shale and four within the shale but
not near active drilling.
Still, Jackson said, "It's an important study that should be
As they push for more natural gas, drilling operators are
increasingly using a process called hydraulic fracturing, or
fracking, which shoots vast amounts of water, sand and chemicals
deep underground to break apart rock and release the gas. Much of
the modern gas boom also involves drilling down and then turning
horizontally to access more gas reserves.
Industry officials insist the process is safe. But the new Texas
study notes a concern among scientists about the lack of hard data
on the drilling boom's potential environmental effects.
"Despite a number of recent investigations, the impact of natural
gas extraction on groundwater quality remains poorly understood,"
the Texas study said.
Another study, published in May by the journal Science, found
that, "It is difficult to determine whether shale gas extraction
in the Appalachian region since 2006 has affected water quality
regionally, because baseline conditions are often unknown or have
already been affected by other activities, such as coal mining."
Last week, The Associated Press reported on what it said were the
"preliminary" results of a U.S. Department of Energy study that
found "no evidence" that drilling chemicals contaminated drinking
water aquifers near at a western Pennsylvania site. The study
marks the first time that a drilling company has allowed
government scientists to inject special tracers into fracking
fluid to monitor if the chemicals spread toward drinking water
Shelley Martin, a spokeswoman for DOE's National Energy Technology
Laboratory, later told the Gazette, "While nothing of concern has
been found thus far, the results are far too preliminary to make
any firm claims."
"We are still in the early stages of collecting, analyzing and
validating data from this site," Martin said in an email earlier
this week. "We expect a final report on the results by the end of
the calendar year."
Martin did not respond to a follow-up request for data from the
"preliminary" results or for an interview with the scientists
involved in the study.
In West Virginia, business and political leaders are eager to
expand natural gas drilling, to tap into the vast reserves
contained in the Marcellus Shale, a formation that stretches from
southern New York and into eastern Ohio.
Between 2003 and 2011, West Virginia's natural gas production more
than doubled to nearly 400 million cubic feet. Over roughly the
same period, employment in the industry increased by 55 percent,
to more than 10,000.
The Obama administration has embraced shale-gas drilling, with the
president saying in a major speech last month that natural gas is
"the transition fuel that can power our economy with less carbon
pollution" as the nation moves toward "the even cleaner energy
economy of the future."
Obama acknowledged that more needs to be done to make natural gas
drilling safe, and noted the need for better control leaks of the
potent greenhouse gas methane from gas production.
At the same time, EPA has backed off major investigations of
drilling impacts on water quality in Wyoming, Pennsylvania and
Texas, and the agency doesn't plan to issue a draft of a
nationwide study of the issue until late 2014.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.