Injection Control Program
Class V Information
What is Underground Injection?
Underground injection is the technology of placing fluids underground, in porous
formations of rocks, through wells or other similar conveyance systems. While
rocks such as sandstone, shale, limestone appear to be solid, they can contain
significant voids or pores that allow water and other fluids to fill and move
through them. The fluids may be water, wastewater or water mixed with
Why Do We Need a Program to Regulate the
Placement of Fluids Underground?
When wells are properly sited, constructed, and operated, underground injection
is an effective and environmentally safe method to dispose of wastes. The
Safe Drinking Water Act established the Underground Injection Control (UIC)
Program to provide safeguards so that injection wells do not endanger current
and future underground sources of drinking water (USDW). The most
accessible fresh water is stored in shallow geological formations called
aquifers and is the most vulnerable to contamination. These aquifers feed our
lakes; provide recharge to our streams and rivers, particularly during dry
periods; and serve as resources for 92 percent of public water systems in the
What Is an Injection Well?
The UIC Program defines an injection well as any bored, drilled or a driven
shaft or a dug hole, where the depth is greater than the largest surface
dimension that is used to discharge fluids underground. A drainfield is
considered to be a horizontally placed injection system, and some drainfields
are covered under the UIC Program.
How Does the UIC Program Regulate the Very
Different Types of Underground Injection?
The EPA 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 consistently to the class.
- Class I includes the 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 II injection wells are regulated by the
Oil & Gas Division);
- Class III encompasses injection of fluids associated with solution mining
of minerals (Class III injection wells are regulated by the
- Class IV addresses injection of hazardous or radioactive wastes into or
above a USDW and is banned unless authorized under a supervised ground water
- Class V includes all underground injection not included in Classes I-IV.
Class V wells inject nonhazardous fluids into or above a USDW and are
typically shallow, on-site disposal systems, such as floor and sink drains
which discharge directly or indirectly to ground water, dry wells, leach
fields, and similar types of drainage wells.
- Injection practices or wells which are NOT covered by the UIC
Program include other individual residential waste disposal systems that
inject ONLY sanitary waste and commercial waste disposal systems that serve
fewer than 20 persons that inject ONLY sanitary waste.
Are All Injection Wells Waste Disposal
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 enhanced recovery of oil
and natural gas, and others inject liquid hydrocarbons that constitute our
Nation's strategic fuel reserves in times of crisis.
How Does the UIC Program Prevent
Contamination of Our Water Supply?
Injection wells have the potential to inject contaminants that may cause our
underground sources of drinking water to become contaminated. The UIC Program
prevents this contamination by setting minimum requirements. The goals of the
EPA's UIC Program are to prevent contamination by keeping injected fluids within
the well and the intended injection zone, or in the case of injection of fluids
directly or indirectly into a USDW, to require that injected fluids not cause a
public water system to violate drinking water standards or otherwise adversely
affect public health. These minimum requirements affect the siting of an
injection well, and the construction, operation, maintenance, monitoring,
testing, and finally, the closure of the well. All injection wells require
authorization under general rules or specific permits.
For additional information about the North Dakota
Underground Injection Control Program or for specific injection well
questions please contact one of the following individuals at the NDDH, Division
of Water Quality: