What is the UIC program?
The Underground Injection Control (UIC) program was established established under the provisions of the Safe Drinking Water Act (SDWA) of 1974. The program is either managed by individual states or by regional EPA offices. The program protects and is designed to prevent contamination of the Underground Sources of Drinking Water (USDW) caused by the operations of an injection well. A USDW is defined as an "aquifer or its portion which supplies any public water system, or contains less that 10,000 milligrams per liter total dissolved solids and is not an exempt aquifer."
Note:
The PADEP and EPA drinking water standard has drinking water should be < 500 mg/L- 99.95 % pure water. 1% contamination is 10,000 mg/L or 99% pure water.
Underground Injection Wells
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, constructed, 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. The Federal UIC program has grouped injection wells into five types or Classes.
Class I wells are technologically sophisticated wells that inject large volumes of hazardous or non-hazardous wastes into deep, isolated rock formations that are seperated 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 hazardous waste fluids disposed of on land. Still, Class I wells inject mostly non-hazardous waste. For example, while all of U.S. industry together injects approximately nine billion gallons of hazardous waster each year, one state alone
Class II wells inject fluids associated with oil and natural gas production. Most of the injected fluid is brine that is produced when oil and gas are extracted from the earth (about 10 barrels of brine for every barrel of oil). The brine is reinjected to increase production, or for disposal. Some Class II wells are used to store hydrocarbon products. Class II wells inject 300 billion gallons of fluid each year. They comprise 41 percent of U.S injection wells.
Class III wells inject super-hot steam or water into mineral formations, which dissolves or loosens minerals, which are then pumped to the surface and extracted. Generally, the fluid is treated and reinjected into the same formation. More than 50 percent of the salt and 80 percent of the uranium extracted in the U.S. are produced this way. Class III wells comprise eight percent of injection wells in the U.S.
Class IV wells are defined in OAC 3745-34-04(D). Class IV wells are shallow wells used to inject hazardous or radioactive wastes into or above a geologic formation that contains an underground source of drinking water (USDW). In 1984, EPA banned the use of Class IV injection wells for disposal of hazardous or radioactive waste. Now, these wells may only be operated as part of an EPA- or state-authorized ground water clean-up action. There are about 32 waste clean-up sites with Class IV wells in the United States.
Most Class V wells are "low tech" holes in the ground, although a few are technologically advanced wastewater disposal systems used by industry. Generally, Class V wells are shallow and rely on gravity to drain or "inject" liquid waste into the ground. Examples of Class V wells include dry wells that collect surface water runoff and industrial, commercial, and utility disposal wells. A Class V well's potential to endanger a nearby ground water resource depends largely on the type and / or quantity of waste fluid it injects.
What is the difference between Class IV and Class V injection wells?
In general, both shallow Class IV and Class V wells inject fluids into or above the uppermost USDW and may be of similar construction, such as a septic system or dry well. The difference between Class IV and Class V wells is the quality of the fluid being injected. Class V wells may only inject non-hazardous fluids that will not endanger USDWs. However, if a Class V well is misused and receives hazardous waste (as defined by RCRA), the well would be considered a Class IV well and therefore be banned.
Class IV wells are prohibited unless the injection wells are used to inject contaminated ground water that has been treated and is being injected into the same formation from which it was drawn.
Comments- Taken from EPAs Website
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