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KELLY AFB TRIES HORIZONTAL WELLSWalters, Dick, Kelly AFB, Texas ECOTONE, Vol 3 No 4, 1999/2000
A handful of horizontal wells at Kelly Air Force Base, Texas, will
substitute for hundreds of yards of trenching alongside a neighborhood that
has expressed concern at the possibility of remedial operations that might
produce noise, dust, and industrial activity very nearly on their doorsteps.
Originally, a Proposed Plan for an Interim Remedial Action to contain
contaminated shallow ground water from a source at the northwest corner of
East Kelly offered a series of collection trenches along the southern and
eastern borders of the base. Wells were recommended as an alternative in areas
where underground utilities made trenches impractical. The goal was to remove
enough water from a capture zone near the base boundary to prevent further
movement of contamination beyond the fence. The proposed trenches would have
been 40 feet deep and 60 feet wide at the surface and would have involved
digging out and replacing hundreds of tons of soil. A series of vertical wells
was found to be costly and possibly insufficient to stop the contamination at
the boundary because of the limited capture area surrounding each well. The
environmental cleanup contractor and the Air Force decided to evaluate
horizontal wells as a technology that could offer an effective and economical
solution. Preliminary ground-water modeling studies indicated that horizontal
wells would contain the shallow underground water as efficiently as the
proposed trenches. A constructability study involving the installation of a
horizontal well began March 9, 1999, on East Kelly. A horizontal well was
installed that was able to affect a 600-foot area from the point where the
drill rig was set up. The test was successful. The noise, dust, and
inconvenience of excavating a trench or installing many wells will be avoided
because each horizontal well affects a large area from a single location. The
ground water is piped to an ultraviolet oxidation treatment system that breaks
down the contamination molecules. Recent advances from the oil industry make
it possible to precisely place a horizontal well in a thin layer of
underground water like the ground-water configuration that exists at East
Kelly. The well drilling equipment enters the ground at a single point, just
as a vertical well would do. Then the drill bit makes an underground turn, so
that the well casing and screened portion where water enters will be sideways,
parallel to the surface. The drilling goes beneath underground utilities
rather than around or through them as a series of wells or a collection trench
would do. Air Force officials say that horizontal wells will result in a
system as efficient as that originally proposed, but less costly and installed
with less disturbance to the neighbors.
The Technology Innovation News Survey welcomes your comments and
suggestions, as well as information about errors for correction. Please
contact Michael Adam of the U.S. EPA Office of Superfund Remediation
and Technology Innovation at adam.michael@epa.gov or (703) 603-9915
with any comments, suggestions, or corrections.
Mention of non-EPA documents, presentations, or papers does not constitute a U.S. EPA endorsement of their contents, only an acknowledgment that they exist and may be relevant to the Technology Innovation News Survey audience.