United States EPA 813-F-94-002
Environmental Protection July 1994
Agency
Office of Water (4602)
Class I Injection
Wells and Your
Drinking Water
9
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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
continually moves, some-times 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 nationwide. Injection wells dispose of
approximately 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 contaminating 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 community 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 surface dimension
and are used to discharge or dispose of fluids
underground. 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 I Well?
Class I wells are technologically sophis-
ticated wells that inject large volumes of
hazardous or non-hazardous wastes into
deep, isolated rock formations that are
separated from the lower most USDW by
layers of impermeable clay and rock.
Although most hazardous waste fluids are
treated and released to surface waters, Class
I wells account for 89 percent of the hazard-
ous waste fluids disposed of on land. Still,
Class I wells inject mostly non-hazardous
waste. For example, while all of U.S. indus-
try together injects approximately nine
billion gallons of hazardous waste each year,
one state alone injects 55 times that amount
in non-hazardous wastes.
Under the UIC Program, EPA and the
states regulate more than 400,000
injection wells. Class I wells comprise
less than one percent of the
injection wells in the U.S.
The chemical, petroleum and metals
industries use most of the Class I hazardous
waste injection wells in the country. The
geology of the Gulf Coast and Great Lakes is
best suited for these types of wells. Thirteen
states have Class I hazardous waste injection
wells; Texas has the most.
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Almost half of the fluids injected into non-
hazardous and municipal waste injection
wells are manufacturing wastes; municipal
effluent accounts for approximately 28% of
the Class I non-hazardous wastes. Florida
has the greatest number of non-hazard-
ous/non-commercial wells, followed by Texas
and Kansas.
How Does EPA Protect
Drinking Water from Class I
Wells?
If Class I waste moves out of the injection
zone, it could threaten underground drinking
water sources. Therefore, EPA's Under-
ground Injection Control program stringently
regulates these wells. A 1989 EPA study
found that injecting wastes in Class I wells is
safer than burying them in landfills, storing
them in tanks, or burning the waste in
incinerators.
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EPA sets minimum design, operation and
siting requirements to ensure that Class I
wells are a safe means of waste disposal.
EPA's standards include provisions that Class
I injection wells must be:
• Constructed with several layers of
concentric tubing and cement to
provide redundant layers of protec-
tion, and
• Sited so that the hazardous fluids
stay within the injection zone for as
long as they remain hazardous.
To ensure that hazardous wastes do not leak
from these wells, EPA requires operators to
test them at least once a year. The operator
also must install and use devices to monitor
waste injection pressure, flow rate, and
temperature. The well is designed to auto-
matically shut down in the event of a well
failure. EPA periodically inspects Class I
wells to confirm that opera-tors are adhering
to Class I regulations. This comprehensive
program prevents contam-ination of under-
ground drinking water sources.
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Through its petition process, EPA requires
operators to show that injected hazardous
waste will remain in the injection zone for
10,000 years, or for as long as the waste
remains hazardous.
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.
U I C
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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
&EPA
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