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| Pad construction on a hilltop in Van Etten, NY |
According to a new report by Penn State soil scientists, 50
to 70 percent of the shale-gas pads that are developed on slopes are prone to
erosion and sedimentation problems. This isn’t surprising, but it’s nice to
have data back up what some of us have suspected all along.
In a press release Patrick Drohan, assistant professor of
pedology and principle investigator for the study, said that the potential for
erosion problems is substantial because of the extensive scale of the shale-gas
play. Not all sites have problems, but at least 10 percent of well pads are
constructed on slopes greater than 8 percent, and Drohan worries about such
areas every time there is an intense rain event.
The problem is that most soils on the Allegheny Plateau,
where shale-gas development is concentrated, are acidic, rocky, shallow and of
poor fertility. About a quarter of the sites are underlain by “fragipan”, a
subsurface horizon that restricts downward root growth and water movement.
(Yup, we’ve got that here in NY, too.) The fragipan layer complicates drainage,
especially where pipelines run down slopes.
The researchers are also concerned about the 21 percent of
pads that have been developed on potentially wet soils – places that
potentially have a water table within 18 inches of the surface. Drainage problems
around those sites could result in the loss of amphibian habitat. Well pad development
in such areas could disrupt local water movement around pad and the recharge to
nearby headwater streams as well.
Drohan and his colleagues are also looking at ecological
disruption caused by shale-gas infrastructure, such as pipelines, that often
traverses steep slopes and poorly drained areas. “We now think that pad
development is a lesser landscape disruption than the pipelines,” said Drohan.
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