GROUND WATER PRIMER - Programs - EPA - Underground Injection Control

epa logo The Underground Injection Control (UIC) Branch was authorized by the Safe Drinking Water Act of 1974 in order to protect underground sources of drinking water (USDWs) from contamination caused by underground injection of fluids through wells.

What's an underground injection well?

Shallow injection wells are typically low-tech holes in the ground that rely on gravity to drain or "inject" liquid wastes into the ground. They often discharge waste fluids into or above drinkable ground water which can then become polluted as contaminants percolate through the soil and eventually reach the aquifers below. Their simple construction provides little or no protection against possible ground water contamination. Injection wells may not only upset the natural recharge volume to aquifers, but may also introduce both thermally and chemically distinct fluids into ground water resources. Shallow injection wells are often located in rural and/or unsewered areas where people depend on ground water for their drinking water. It is estimated that more than 1 million of these wells exist nationwide.

Are all injection wells basically the same?

Although similar in their basic function, there are many different types of injection wells. UIC wells are regulated in five different classes which characterize injection wells by the nature of the fluid injected, and by the relationship between the geologic strata into which the fluid is injected and the lowest USDW. The most common UIC wells are Class II wells (related to the oil and gas industry), and Class V wells (a more general class that includes wells which do not fit into the other four classes). Common examples of Class V wells are industrial wastewater disposal into septic systems, and septic systems connected to automotive service station bays.

Injection wells vary in their potential to contaminate ground water. The risk depends on various factors including the types of waste fluids injected, well construction, local geology, and well location in proximity to local water supply. Class V shallow injection wells have the greatest potential to adversely impact drinkable ground water.

What are injection wells used for?

Shallow injection wells are mainly used for drainage, discharge, or disposal of unwanted fluids. The broad definition of an injection well, which is basically any hole in the ground whose depth is greater than its largest surface dimension, brings a number of underground systems under this classification. Except for disposal systems serving single families or systems serving less than 20 persons, sumps, septic systems, cesspools, and drain fields are classified as injection wells. Misuse of these systems for disposal of anything other than domestic or sanitary waste can pose a substantial threat to ground water. Other types of injection wells include drywells, improved sinkholes, mine drainage and backfill wells, seepage pits, catch basins, french drains, and retention ponds. Any business or operation that provides a product or service and whose sinks or drains are not connected to a sewer could have a shallow injection well. Communities without storm sewer systems often use shallow injection wells to control flooding during storm events.

How does EPA regulate injection wells?

Any underground injection into a well is prohibited unless the well is authorized by rule or authorized by a UIC permit. Injection well owners are required by law to submit inventory information to USEPA or the state delegated agency. UIC owners must not endanger USDWs.

Does your facility generate industrial wastewaters? The UIC program encourages voluntary compliance through education and technical assistance, but penalizes owners and operators of injection wells who violate UIC requirements. Once injection well owners understand how "old habit" practices of handling wastes can cause harm to the environment, most usually want to cooperate and address the problem. However, for those that do not comply voluntarily, USEPA is prepared to take Federal enforcement action necessary to protect the environment. This will include penalties, a schedule for compliance, and for blatant disregard of USEPA regulations, even imprisonment.

How Does the UIC Program Protect Your Drinking Water?

The UIC program is responsible for ensuring that injection wells are inventoried, permitted as necessary, monitored for compliance, and as the situation warrants, properly closed. The UIC program ensures that these occur by requesting information, responding to citizen complaints, reviewing submitted documentation, tracking data, maintaining files, identifying potential contamination sources, conducting on-site inspections, and providing public outreach and education.

Shallow injection wells are difficult to regulate because they are inconspicuous, extremely diverse, and large in number. As such, EPA must target the most significantly threatening types of Class V wells with focus on source water protection areas and control the types of wastes operatores are alllowed to inject.

Most states, working in partnership with EPA, administer their own UIC programs. If a state cannot administer the program or chooses not to do so, EPA administers the program directly.

Federal and state UIC programs help protect drinking water resources, but must have local support. USEPA works in partnership with state and local governments to prevent injection wells from contaminating your drinking water resources. Local governments and citizens themselves are often in the best position (and have the greatest incentive) to ensure that injection wells do not endanger USDWs, 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.

For more information on injection wells and the UIC program, please download a copy of the Class V Injection Well software from http://www.epa.gov/seahome/inject.html

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