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EPA
EPA810F-99-019
December 1999
USEPA's Program to Regulate the
Placement of Waste Water and
other Fluids Underground
SAFE DRINKING WATER ACT • CELEBRATING 25 YEARS • PROTECT OUR HEALTH FROM SOURCE TO TAP
Why Do We Need a Program to
Regulate the Placement of Fluids
Underground?
Facilities across the United States, including
Indian Country, discharge into underground
formations a variety of hazardous and nonhaz-
ardous fluids into more than 400,000 injection
wells. Our way of life would be quite different
without injection wells. Agribusiness and the
chemical and petroleum industries as we know
them today, could not exist. While treatment
technologies exist, it would be cost prohibitive
to treat and release to surface waters the billions
and trillions of gallons of wastes that industries
produce each year. When wells are properly
sited, constructed, and operated, underground
injection is an effective and environmentally safe
alternative to surface disposal.
The Underground Injection Control (UIC) Pro-
gram provides these safeguards so that injection
wells do not endanger underground sources of
drinking water (USDW). The most accessible
fresh water is stored in shallow geological
formations called aquifers and is the most vulner-
able to contamination. These aquifers feed our
lakes; provide recharge to 41 percent of our
streams and rivers, particularly during dry peri-
ods; and serve as resources for 89 percent of
public water systems in the United States.
What Is an Injection Well? An injection well is
used for subsurface emplacement of fluids. An
injection well is a bored, drilled, or driven shaft
whose depth is greater than the largest surface
dimension; or, a dug hole whose depth is
greater than the largest surface dimension; or,
an improved sinkhole; or, a subsurface fluid
distribution system. This definition covers a
wide variety of injection practices that range
from more than 100,000 technically sophisti-
cated highly monitored wells which pump fluids
into isolated formations up to two miles below
the Earth's surface, to the far more numerous on-
site drainage systems, such as cesspools, leach
fields, and storm water wells, that discharge
fluids a few feet underground.
How Does the UIC Program Regulate
the Very Different Types of Under-
ground Injection?
USEPA groups underground injection into five
classes for regulatory control purposes. Each
class includes wells with similar functions, and
construction and operating features so that
technical requirements can be applied consis-
tently to the class.
• Class I includes emplacement of hazardous
and nonhazardous fluids (industrial and
municipal wastes) into isolated formations
beneath the lowermost USDW. Because they
may inject hazardous waste, Class I wells are
the most strictly regulated and are further
regulated under the Resource, Conservation
and Recovery Act.
• Class II includes injection of brines and other
fluids associated with oil and gas production.
• Class III encompasses injection of fluids
associated with solution mining of minerals.
« Class IV addresses injection of hazardous or
radioactive wastes into or above a USDW and
are banned unless authorized under other
statutes for ground water remediation.
• Class V includes all underground injection
not included in Classes I-IV. Generally, most
Class V wells inject nonhazardous fluids into
or above a USDW and are on-site disposal
systems, such as floor and sink drains which
discharge to ground water, cesspools, leach
fields, and drainage wells. Injection practices
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or wells which are not covered by the UIC Program
include septic systems and cesspools that serve
fewer than 20 persons that inject ONLY sanitary
waste water.
Are All Injection Wells Waste Disposal
Wells?
All injection wells are not waste disposal wells - some
Class V wells, for example, inject surface water to
replenish depleted aquifers or to prevent salt water
intrusion. Some Class II wells inject fluids for en-
hanced recovery of oil and natural gas, and others
inject liquid hydrocarbons that constitute our nation's
strategic fuel reserves in times of crisis. But most
injection wells have the potential to inject fluids that
may cause a public water system to violate National
Drinking Water Standards. These standards provide
our safety net^against waterborne disease and other
health risks.
How Does USEPA's UIC Program Prevent
Contamination of Our Water Supply?
In general, USEPA's UIC Program prevents contamina-
tion of water supplies by setting minimum require-
ments for state UIC Programs. A basic concept of
USEPA's UIC Program is to prevent contamination by
keeping injected fluids within the well and the in-
tended injection zone, or in the case of injection
directly or indirectly into a USDW, the fluids must not
endanger or have the potential to endanger a public
water supply in the future. Most of the minimum
requirements that affect the siting of the injection well,
the construction, operation, maintenance, monitoring,
testing, and finally, the closure of the well, are designed
to address these concepts. Another basic concept is
that all injection wells require authorization under
general rules or specific permits. Finally, states are
expected to have primary enforcement authority (pri-
macy) for the UIC Program, not the federal government.
To date, 33 states, Guam, Commonwealth of the
Mariana Islands, and Puerto Rico have obtained pri-
macy for all classes of injection wells. Seven states
share primacy with USEPA. The USEPA administers
UIC programs for the remaining ten states, and all other
federal jurisdictions and Indian Country.
The UIC Program Protects More Than
Ground Water
The UIC Program:
• Reduces human exposure to organic and inorganic
chemicals and heavy metals by removing them
from the environment
• Eliminates more than nine billion gallons of haz-
ardous waste and a trillion gallons of oil field
waste from the environment each year
• Decreases public water system costs for water
treatment
• Avoids cost of ground water remediation, medical
monitoring for health effects, and replacing a
drinking water supply
• Reduces pollution of wellhead and source water
protection areas, rivers, streams, lakes, wetlands,
watersheds, estuaries and coastal zones
• Enables communities to make wise local land use
decisions
For More Information about USEPA's UIC Program
Contact: EPA's Safe Drinking Water hotline (800)
426-4791 or the Office of Ground Water and Drinking
Water (202) 260-7077. Write to: The UIC Program,
Mail Code 4606, U.S. EPA, 401 M Street S.W., Wash-
ington, D.C. 20460. Please visit the web site at
www.epa.gov/safewater.
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