United States
Environmental Protection
Agency
Office of Water
(4606)
Washington, DC 20460
EPA816-H-01-003
August 2001
www.epa.gov/safewater
Safe Drinking Water Act
Underground Injection Control (UIC) Program
Protecting Public Health and Drinking Water Resources
Class I wells-
Isolate hazardous,
industrial and municipal
wastes through
deep injection
CHEMICAL
I PLANT
Class II wells-
Inject oil and gas
production wastes
Class III wells-
Minimize
environmental impacts
from solution mining
operations
rf^WASTE WATER
TREATMENT PLANT
«--
•• r
TREATED
WASTE WATER
WAbTE WATEK
DRINKING WATER
RESOURCES
BASE OF
UNDERGROUND
SOURCES OF
.NKING WATER
CONFINING
FORMATIO
CONFINING
:ORMAT|ON
CONFINING
iFORMATIOH
HAZARDOUS
AND NON-HAZARDOUS
INDUSTRIAL WASTES
CONFINING
IFORMATIO
CONFINING
FORMATIO
BASE OF
UNDERGROUND
SOURCES OF
DRINKING WATER
' i ' SALT LAYER
^K t
'PRODUCTION WELLS ARE NOT
REGULATED BY THE UIC PROGRAM
Class IV wells-
Prevent ground water
contamination
by prohibiting
the shallow injection
of hazardous waste
except as part of
authorized
cleanup activities
J
'PRODUCTION WELLS ARE NOT
REGULATED BY THE UIC PROGRAM
APARTMENT*.
BUILDING*
AUTOMOTIVE -
SERVICE STATION
INDUSTRIAL .
WASTE
STORM WATER
DRAINAGE
LARGE-CAPACITY
SEPTIC SYSTEMS
DRINKING
WATER
RESOURCES
BASE OF
UNDERGROUND
SOURCES OF
NKING WATER
In your community, there may be industrial
waste disposal wells, storm water drainage wells,
large-capacity septic systems,
and other Class V wells.
They are regulated and are
not allowed to endanger drinking water resources.
Class V wells continued
LIGHT INDUSTRY
WITH HOLDING TANKS
FOR OFF-SITE WASTE
DISPOSAL
DRINKING WATER PLANT
LARGE-CAPACITY
CESSPOOL
PUBLIC
WATER
SUPPLY
WELL
AGRICULTURAL
DRAINAGE WELL
DRINKING WATER
RESOURCES
BASE OF
UNDERGROUND
SOURCES OF
DRINKING WATER
MOTOR VEHICLE
WASTE
DISPOSAL WELL
All large-capacity
cesspools are banned.
New motor vehicle waste
disposal wells are
banned nationwide.
Existing motor vehicle
waste disposal wells in
source water protection
areas or other sensitive
ground water areas must
close or receive a
permit.
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Safe Drinking Water Act
Underground Injection
Control (UIC) Program
Protecting Public Health and Drinking
Water Resources
WHY Do WE HAVE A PROGRAM TO REGULATE
UNDERGROUND INJECTION?
Each year Americans generate large amounts of waste
fluids. More than 750 billion gallons of hazardous and non-
hazardous fluids are disposed of safely through under-
ground injection. The Underground Injection Control (UIC)
Program is designed to protect underground sources of
drinking water (USDWs) and provide a safe and cost-
effective means for industries, municipalities, and small
businesses to dispose of their wastewater, extract mineral
resources, and store water for the future. Illegal discharges
have the potential to contaminate our underground drinking
water resources. Preventing this contamination is vital
because most accessible fresh drinking water is found
underground in shallow formations called aquifers. Aquifers
provide water for more than 90 percent of the public water
systems in America. They also supply agricultural wells,
feed our lakes, and help recharge our streams and rivers,
particularly during dry periods. In addition, millions of
Americans living in rural areas rely on private wells that
draw their water from aquifers. Safe and clean drinking
water resources are essential for our growing population.
Protecting future drinking water resources is essential for
continued growth. The UIC Program prevents contaminants
from entering our drinking water resources to protect our
public health.
WHAT ARE INJECTION WELLS?
An injection well is any bored, drilled, or driven shaft, or dug
hole, whose depth is greater than its largest surface
dimension; an improved sinkhole; or a subsurface distribu-
tion system used to discharge fluids underground. These
wells range from deep, highly technical, and more frequently
monitored wells to shallow on-site drainage systems, such
as septic systems, cesspools, and storm water drainage
wells. There are five categories or "classes" of injection
wells based on function, construction, and operating
features.
WHAT Is THE STATUTORY BASIS FOR THE UIC
PROGRAM?
In 1974, Congress passed the Safe Drinking Water Act
(SDWA). Part of SDWA required the U.S. Environmental
Protection Agency (EPA) to report back to Congress on
waste disposal practices, and develop minimum federal
requirements for injection practices that protect public
health by preventing injection wells from contaminating
USDWs. USDWs are defined as aquifers or portions of
aquifers that have a sufficient quantity of ground water to
supply a public water system and contain fewer than 10,000
milligrams per liter (mg/l) or parts per million (ppm) total
dissolved solids (water that can be treated to drinking water
standards). This includes all current and future underground
drinking water resources.
How DOES THE UIC PROGRAM PROTECT PUBLIC HEALTH?
EPA established the UIC Program to set minimum federal requirements for all
injection wells that discharge hazardous and non-hazardous fluids above,
into, or below USDWs. They affect the siting, construction, operation, mainte-
nance, monitoring, testing, and closure of injection wells. All operational
injection wells require authorization under general rules or specific permits.
Fluids cannot be injected if they may endanger a drinking water source.
I Class I wells - Isolate hazardous, industrial and municipal wastes
through deep injection. Class I wells inject hazardous and non-
hazardous wastes into deep, isolated rock formations below the
lowermost USDW. There are specific siting, construction, operating,
monitoring and testing, reporting and record keeping, permitting, and
closure requirements for all Class I wells. There are two main types of
Class I wells: hazardous waste wells and non-hazardous waste wells.
4 Class I Hazardous Waste Disposal Wells are mainly used by
industries such as petroleum refining and metal, chemical, and
pharmaceutical production. These wells inject up to 2 miles below
the surface and are designed to prevent any waste from escaping
the injection zone. Because of the hazardous nature of the waste,
Class I hazardous well owners must also show that the hazardous
waste will not move from the injection zone for 10,000 years, or for
as long as the waste remains hazardous. Eighty-nine percent of all
hazardous waste disposal in the United States is done through Class
I wells. Class I hazardous waste wells are stringently regulated under
the SDWA (UIC Program) and the Resource, Conservation and
Recovery Act (RCRA). There are approximately 120 Class I hazard-
ous wells in operation in the United States.
4 Class I Non-Hazardous Waste Disposal Wells are used by industries
and municipal wastewater treatment facilities to dispose of non-
hazardous waste, such as dilute manufacturing process waste and
treated sanitary wastewater. All Class I non-hazardous wells are
monitored, inspected, and tested regularly. There are approximately
380 Class I non-hazardous wells operating in the United States.
I Class II wells - Inject oil and gas production wastes and materials.
Class II wells inject fluids associated with oil and natural gas produc-
tion. Most of the injected fluid is brine pumped to the surface along with
oil and gas. This brine is often saltier than seawater and can contain
toxic metals and radioactive substances. By injecting the brine, Class II
wells prevent surface contamination of soil and water. In addition, well
operators inject residual brines, steam, polymers, and other fluids to
enhance the production of oil and gas. Class II well operators must
follow strict construction and conversion (from production wells)
requirements, except when historical practices in the state and geology
allow for different standards. Class II wells are permitted or authorized
by rule; the well owner or operator must meet all applicable require-
ments; and the wells are tested and inspected regularly. There are
about 147,000 Class II wells in operation in the United States.
I Class III wells - Minimize environmental impacts from solution
mining operations. Class III wells inject fluids into rock formations to
dissolve and extract minerals. The injected fluids are pumped to the
surface and the minerals in solution are extracted. Generally, the fluid is
recycled into the same formation for further mineral extraction. More
than 50 percent of the salt and 80 percent of the uranium extraction in
the United States involves Class III injection wells. These wells are
permitted or authorized by rule. Class III well owners or operators must
case and cement their wells, and the wells must be tested regularly.
There are about 190 mining sites with approximately 17,000 Class III
wells operating in the United States.
I Class IV wells - Prevent ground water contamination by prohibiting
the shallow injection of hazardous waste except as part of autho-
rized cleanup activities. Class IV wells were shallow wells used to
inject hazardous or radioactive wastes. They are banned except when
operated to inject treated contaminated ground water back into the
original aquifer. These wells can be operated only with federal or state
approval under the RCRA or Superfund programs. There are about 40
waste cleanup sites with Class IV wells in operation in the U.S.
Class V wells - Manage the shallow injection of all other fluids.
Class V wells are injection wells that are not included in Classes I
through IV Class V wells inject non-hazardous fluids into or above an
aquifer. They are typically shallow, on-site disposal systems, such as
floor and sink drains that discharge into dry wells, septic systems, leach
fields, and similar types of drainage wells, although there are some
Class V wells that are deep injection wells. When properly designed,
sited, operated, and maintained, Class V wells do not endanger drinking
water sources. Most Class V wells are authorized by rule. An estimated
500,000 to 685,000 Class V wells are in operation in the United States.
Examples of Class V wells include the following:
4 Agricultural Drainage Wells are used to drain farmland for cultivation.
They include improved sinkholes, abandoned drinking water wells,
and underground drain tiles and cisterns.
4 Industrial Waste Disposal Wells are used to dispose of non-hazard-
ous industrial or commercial waste and fluids. These wastes and
fluids include wastewater from a wide variety of industries including
petroleum refineries, carwashes, laundromats, commercial printers,
food processors, chemical manufacturers, electroplaters, small
machinery, tool and die, and other industrial operations.
4 Large-Capacity Cesspools are typically drywells that receive un-
treated sanitary waste and which have an open bottom and, some-
times, perforated sides. Large-capacity cesspools are used by
multiple dwelling units, business establishments, community or
regional establishments such as churches and shopping malls, and
other facilities such as camp grounds and highway rest stops. New
large-capacity cesspools are banned and existing large-capacity
cesspools must close.
4 Large-Capacity Septic Systems are on-site systems that partially
treat and dispose of sanitary wastewater. Most large-capacity septic
systems consist of a septic tank and a leach field. Large-capacity
septic systems are used by multiple dwelling units, business estab-
lishments, community or regional establishments, and other facilities.
4 Motor Vehicle Waste Disposal Wells are used to dispose of fluids
from the repair or maintenance of motor vehicles. Fluids entering
these wells include organic chemicals such as petroleum products
and inorganic chemicals such as heavy metals. New motor vehicle
waste disposal wells are banned and existing wells must close or
receive a permit.
4 Saline Intrusion Barrier Wells (not shown) are used to inject water
into an aquifer to prevent intrusion of salt water into that aquifer.
4 Storm Water Drainage Wells are used to remove storm water and
urban runoff from surfaces such as roadways, roofs, and paved
surfaces to prevent flooding.
4 Subsidence Control Wells (not shown) are used to control land
sinking, or subsidence, caused by ground water withdrawal.
NOTE: The UIC Program does not regulate sanitary discharges from
individual residential septic systems and cesspools, and nonresiden-
tial septic systems and cesspools that inject only sanitary waste and
have the capacity to serve fewer than 20 persons per day.
There are many other subcategories of Class V wells. Additional information
can be found by visiting EPA's UIC Program Web site at http://www.epa.gov/
safewater/uic.html.
WHO IMPLEMENTS THE UIC PROGRAM?
States and tribes may apply to EPA to obtain primary
enforcement responsibility, or primacy, to administer the UIC
Program. Primacy programs must meet the minimum
federal requirements, but may have more stringent require-
ments. Thirty-three states, Guam, the Commonwealth of the
Mariana Islands, and Puerto Rico have primacy for all
classes of injection wells. Seven states share primacy with
EPA. EPA directly implements the UIC programs for the
remaining states, the Virgin Islands, American Samoa, and
Indian Country.
WHAT CAN You Do TO PROTECT YOUR DRINKING
WATER?
Preventing contamination can save you money and protect
your family's health. Here are some of the things you can do
to help protect your drinking water source:
• Know where your drains go. Many homes or
businesses use septic systems or drywells for waste
disposal. These systems are designed for household
sanitary wastes only.
• Become involved in Source Water Protection.
Every state is conducting Source Water Assessments
for its public water systems. These assessments will
identify the major potential sources of contamination
(including Class V wells) to public drinking water
supplies. The results will be provided to the public.
Communities will use this information to plan protec-
tion activities and identify Class V wells for proper
management to prevent contamination of drinking
water sources. The UIC Program has banned motor
vehicle waste disposal wells in source water protec-
tion areas. States are also encouraged to target these
areas for UIC protective measures.
• Read your consumer confidence report. This
report, published once a year by the agency providing
you with your drinking water, gives you information
about the quality of your drinking water and informa-
tion about your state's source water assessment for
your system, when it has been completed.
FOR MORE INFORMATION:
Call the 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, 1200
Pennsylvania Avenue, NW, Washington, D.C. 20460; or visit
the Web site at http://www.epa.gov/safewater/uic.html.
DEFINITIONS
IMPROVED SINKHOLE - A naturally occurring depression or other natural
crevice (for example, those found in limestone or volcanic rocks),
which has been modified for the purpose of directing and discharging
fluids underground.
SUBSURFACE DISTRIBUTION SYSTEM - An assemblage of perforated pipes,
drain tiles, or other similar mechanisms intended to distribute fluids
below the ground surface.
AUTHORIZATION BY RULE - An owner or operator of an injection well who
submits proper inventory information to the UIC regulatory authority
may construct or use his or her well as long as the injection activity
does not endanger USDWs.
NON-ENDANGERMENT - No owner or operator shall construct, operate,
maintain, convert, plug, abandon, or conduct any other injection ac-
tivity in a manner that allows the movement of fluid containing any
contaminant into USDWs, if the presence of that contaminant may
cause a violation of any primary drinking water regulations or may
adversely affect the health of persons.
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