A Citizen's Guide to
Fracturing for Site Cleanup
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What Is Fracturing For Site Cleanup?
Fracturing creates or enlarges openings in bedrock or
dense soil, such as clay, to help soil and groundwater
cleanup methods work better. The openings, called
"fractures," become pathways through which
contaminants in soil and groundwater can be
treated in situ (in place, underground) or removed
for above-ground treatment. Although fractures can
occur naturally in soil and rock, they are not always
wide or long enough to easily reach underground
contamination using cleanup methods. Fracturing can
enlarge the cracks and create new ones to improve
the speed and effectiveness of the cleanup. Fracturing
is most commonly used with several in situ cleanup
methods. (See A Citizen's Guide to Bioremediation
[EPA 542-F-12-003], In Situ Chemical Oxidation [EPA
542-F-12-011], In Situ Chemical Reduction [EPA
542-F-12-012]), and Soil Vapor Extraction and Air
Sparging [EPA 542-F-12-018]).
How Does It Work?
There are three ways to fracture soil or rock:
• Hydraulic fracturing pumps water or a water-based
fluid under pressure into holes drilled in the
'..•' •; .'••'..'.- './_'[ -'.Sandy Soil
How Is Fracturing for Environmental
Cleanup Different from Fracturing
to Recover Oil and Gas?
Oil and gas hydraulic fracturing is used to stimulate
the recovery of oil or natural gas from underground
geologic formations. Oil and gas hydraulic fracturing
works by pumping a mixture of fluids and other
substances into the target formation to create and
enlarge fractures. Such operations are much larger,
use different equipment and chemical additives, occur
at greater depths, and use higher volumes of fluid
than fracturing for site cleanup. Fracturing to clean
up a contaminated site rarely exceeds a depth of 100
feet, and the affected area around the fracturing well
usually is less than 100 feet in any direction. However,
wells to extract oil and gas often are drilled hundreds or
thousands of feet downward and sometimes horizon-
tally into the oil- or gas-bearing rock. Fractures may
extend over 500 feet from these wells.
ground. The force of the water causes soil (or
sometimes rock) to fracture. The water or fluid can
be pumped with sand or other "propping agents."
Propping agents help keep the fractures open
during cleanup.
• Pneumatic fracturing injects air or other gases into
the holes to fracture dense soil. Air forced into the
soil also can promote evaporation of chemicals
that change to gases quickly when exposed to air.
The gases may be captured and treated above
ground.
• Blast-enhanced fracturing uses explosives, such
as dynamite, to fracture rock. The explosives are
placed in holes and detonated. The main purpose
is to create fractures for pump and treat cleanup.
Both pneumatic and hydraulic fracturing can
direct pressure to specific underground zones, but
blast-enhanced fracturing cannot.
Nitrogen gas is injected for pneumatic fracturing of bedrock.
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How Long Will It Take?
Fracturing rock and soil does not take very long. It may only take a few days.
However, even with the help of fracturing, actual cleanup may take months or
years, depending on several factors. For example, it will take longer where:
• The contaminated area is large or deep.
• Contaminant concentrations are higher.
• Groundwater flow is slow.
Is Fracturing Safe?
When properly used, fracturing is a safe way to make cleanup methods faster
and more efficient. Because fracturing affects the soil and bedrock, it is not
typically used where it can affect building foundations and underground utilities.
To be sure fracturing does not damage nearby structures, special monitoring
equipment is used to measure any movement of the ground. When fracturing
is conducted at shallow depths, the ground surface around the holes may rise
as much as an inch, but will eventually settle back close to its original level if
fractures are not propped open.
How Might It Affect Me?
Residents near the site may see increased truck traffic when fracturing
equipment and materials needed for cleanup are delivered to the site.
Residents also may hear noise from the detonation of explosives and from
machines used to inject water or air underground.
Why Use Fracturing For Site Cleanup?
Fracturing is used to help
reach contaminants in rock
and dense soil so that they
can be cleaned up faster
and more completely. It
offers a way of reaching
contamination deep in the
ground where it would be
difficult or costly to excavate.
Fracturing can reduce the
number of wells needed for
certain cleanup methods,
which can save time and
reduce cleanup costs.
Fracturing has been used in cleanups at over 15 Superfund sites and many
more sites throughout the country.
Pneumatic fracturing at the Hunters Point Naval Shipyard
Superfund site
Example
Pneumatic fracturing was used
to help clean up an area of the
Hunters Point Naval Shipyard
Superfund site in California. For
years the site was used for ship
building and maintenance, which
contaminated groundwater with
fuels, pesticides, heavy metals,
industrial solvents, and other
chemicals.
To clean up solvents from the
groundwater, EPA needed to inject
small particles of iron underground
over an area larger than an acre
to reach contaminants from 5 to
25 feet below ground. Pneumatic
fracturing by high-pressure
injection of nitrogen gas was used
to create and widen fractures in
soil. The fractures allowed the
injected iron to spread more widely
and evenly underground and
treat more of the contaminated
groundwater. After 12 weeks,
solvent concentrations within the
treatment areas decreased by
an average of 87 to 99 percent.
Additional monitoring is being
conducted as part of the site-wide
groundwater monitoring program.
For More Information
For more information on this and
other technologies in the Citizen's
Guide Series, contact:
U.S. EPA
Technology Innovation &
Field Services Division
Technology Assessment Branch
(703)603-9910
Or visit:
www.cluin.org/techfocus/default.
focus/sec/Fracturing/cat/Overview/
NOTE: This fact sheet is intended solely as general information to the public. It is not intended, nor can it be relied upon, to create any
rights enforceable by any party in litigation with the United States, or to endorse the use of products or services provided by specific
vendors. The Agency also reserves the right to change this fact sheet at any time without public notice.
United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
(5102G)
EPA 542-F-12-008
September 2012
www.epa.gov/superfund/sites
www.cluin.org
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