In communities across the U.S., people are hearing more and more
about a controversial oil and gas extraction technique called hydraulic
fracturing -- aka, hydro-fracking. Controversies pivot on some basic questions:
Can hydro-fracking contaminate domestic wells? Does it cause earthquakes? How
can we know? What can be done about these things if they are true?
"When people talk about contamination from hydraulic
fracturing, for instance, they can mean a lot of different things," says
hydrogeologist Harvey Cohen of S.S. Papadopulos & Associates in Bethesda,
Maryland. "When it's what's happening near their homes, they can mean
trucks, drilling machinery, noise." These activities can potentially lead to
surface water or groundwater contamination if there are, for example,
accidental fuel spills. People also worry about fracking fluids leaking into
the aquifers they tap for domestic or municipal water.
On the other hand, when petroleum companies talk about risks to
groundwater from hydro-fracking, they are often specifically referring to the
process of injecting fluids into geologic units deep underground and fracturing
the rock to free the oil and gas it contains, says Cohen. This is a much
smaller, much more isolated part of the whole hydraulic fracturing operation.
It does not include the surface operations -- or the re-injection of the
fracking waste fluids at depth in other wells, which is itself another source
of concern for many.
But all of these concerns can be addressed, says Cohen, who will
be presenting his talk on groundwater contamination and fracking on the morning
of Nov. 7. For instance, it has been proposed that drillers put non-toxic
chemical tracers into their fracking fluids so that if a nearby domestic well
is contaminated, that tracer will show up in the well water. That would sort
out whether the well is contaminated from the hydro-fracking operations or
perhaps from some other source, like a leaking underground storage tank or surface
contaminants getting into the groundwater.
"That would be the 100 percent confident solution," says
Cohen of the tracers.
Another important strategy is for concerned citizens, cities, and
even oil companies to gather baseline data on water quality from wells before
hydro-fracking begins. Baseline data would have been very helpful, for example,
in the case of the Pavillion gas field the Wind River Formation of Wyoming,
according to Cohen, because there are multiple potential sources of
contaminants that have been found in domestic wells there. The Pavillion field
is just one of multiple sites now being studied by the U.S. Environmental
Protection Agency (EPA) to learn about past and future effects of
hydro-fracking on groundwater.
The same pre-fracking science approach is being taken in some
areas to evaluate the seismic effects of disposing of fracking fluids by
injecting them deep underground. In Ohio and Texas, this disposal method has
been the prime suspect in the recent activation of old, dormant faults that
have generated clusters of low intensity earthquakes. So in North Carolina, as
well as other places where fracking has been proposed, some scientists are
scrambling to gather as much pre-fracking seismic data as possible.
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