United States EPA 813-F-94-004
Environmental Protection July 1994
Agency
Office of Water (4602)
Class '" Injection
Wells and Your
Drinking Water
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M ore than 89 percent of U.S. public
water supply systems draw some
or all of their drinking water from
sources found underground in rock,
sand, and gravel. Ground water also
feeds rivers, lakes, and streams used for
drinking water. Ground water has no
respect for state boundaries. It contin-
ually moves, sometimes recharging
surface waters hundreds of miles away
from where it started.
Most ground water used for drinking
is located near the earth’s surface and
is easily contaminated. Of major
concern is the potential contamination
of underground sources of drinking
water (USDWs) by any of the hundreds
of thousands of injection wells nation-
wide. Injection wells dispose of approxi-
mately 11 percent of the nation’s fluid
waste.
The U.S. Environmental Protection
Agency (EPA) is working in partnership
with state and local governments to
prevent injection wells from contamin-
ating your drinking water resources.
You can help by learning about EPA’s
Underground Injection Control (UIC)
program so that you can identify
injection wells in your com-munity that
may contaminate your drinking water.
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Basically, injection wells are man-made
or improved "holes" in the ground,
which are deeper than their widest sur-
face dimension and are used to dis-
charge or dispose of fluids under-
ground. When properly sited, con-
structed, and operated, injection wells
can be an effective and environmentally
safe means of fluid waste disposal
There are many different types of
injection wells, but they are all similar
in their basic function.
What is a Class III Well?
Class III wells inject super-hot steam
or water into mineral formations, which
dissolves or loosens minerals, which are
then pumped to the surface and
extracted. Generally, the fluid is
treated and reinjected into the same
formation. More than 50 percent of the
salt and 80 percent of the uranium
extracted in the U.S. are produced this
way. Class III wells comprise eight
percent of injection wells in the U.S.
Under the UIC Program, EPA and
the states regulate more than
400,000 injection wells. Class III
wells comprise 8 percent of the
injection wells in the U.S.
Class III wells are used to recover salt,
sulfur, or uranium Operators of Class
III injection wells can use either of the
following safe and environmentally
sound techniques to extract minerals
from the ground:
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• Solution Mining: used primarily
to extract salt and sulfur from
underground formations. Well
operators inject water to extract
salt and super-heated steam to
melt and extract sulfur.
• In Situ Leaching: commonly
used to extract uranium, and in
some instances gold and copper
from the ground. A non-toxic
chemical solution is circulated,
which dissolves or “leaches”
mineral particles from the
sand grains in the ore body.
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How Does EPA Protect
your Drinking Water
from Class Ill Wells?
Federal and state Class III regulations
are designed to prevent the endanger-
ment of underground drinking water
sources. Class III wells must conform
to state and federal construction stand-
ards. These standards ensure that
fluids injected by Class III wells do not
move into and contaminate under-
ground sources of drinking water.
They require Class III well operators to:
•case and cement their wells to
prevent the migration of fluids into
an underground drinking water
source:
• never inject fluids between the
outer-most casing and the well
bore; and
• test the well casing for leaks at
least once every five years.
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Many states regulate Class III wells more
stringently than do the federal authorities.
For example, the states may require aimual
inspections of Class III injection wells and
mechanical integrity tests prior to a well’s
initial operation.
How Can You Help?
Federal and state UIC programs help
protect drinking water resources, but must
have local support. Local governments and
citizens themselves often are in the best
position (and have the greatest incentive)
to ensure that injection wells do not
endanger underground drinking water
sources, public health, and the
environment. To find out more about the
UIC program and what you can do to
protect your drinking water, contact your
EPA Regional Office.
uIc
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For information contact:
Region 1
Ground Water Management Section
John F. Kennedy Federal Building
One Congress Street
Boston, MA 02203 (617) 565-3615
Region 2
Underground Injection Control Section
26 Federal Plaza, Room 853
New York, NY 10278 (212)264-1547
Region 3
Underground Injection Control Section
841 Chestnut Building (3WM43)
Philadelphia, PA 1910 (215)597-9928
Region 4
Underground Injection Control Section
(GWP-3)
345 Courtland Street N E
Atlanta, GA 30365 (404)347-3379
Region 5
Underground Injection Control Section
(WD-17J)
77 W. Jackson Street
Chicago, IL 60604 (312)886-1492
Region 6
Underground Injection Control Program
(6W-SE)
1445 Ross Avenue
Dallas, TX 75202-2733 (214)655-7160 or
(214) 655-7165
Region 7
Underground Injection Control Section
726 Minnesota Avenue
Kansas City, KS 66101 (913)551-7369
Region 8
UIC Program/Enforcement Section
(8WM-DW)
999 18th Street - Suite 500
Denver, CO 80202-2466 (303)293-1413
Region 9
Source Water Protection Section (W-6-2)
75 Hawthorne Street
San Francisco, CA 94105 (415)744-1838
Region 10
Ground Water Section (WD-133)
1200 Sixth Avenue
Seattle, WA 98101 (206)553-1369
6EPA
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