Class III

Class III wells are used to inject fluids to dissolve and extract minerals.  Production wells, which bring mining fluids to the surface, are not regulated under the Underground Injection Control (UIC) program. Approximately 165 mining sites utilize Class III wells in mining operations across the nation. Companies mine uranium, salt, copper, and sulfur using Class III wells. In the United States, more than 50% of the salt and 80% of the uranium extraction involve Class III injection wells. 1

Underground Injection Wells by Class

Injection Well ClassNumber of Injection WellsInjection Wells Inspected
Class I830453
Class II181,43184,317
Class III28,327406
Class IV12227
Class V531,1764,038
Class VI20

Source: EPA2

Class IV EPA UIC Wells
Class III EPA UIC Wells

1. USEPA. (2022, July 22). Class III injection wells for solution mining. Retrieved 12/30/2022 from

2. USEPA. (2020). Underground Injection Control Program Fact Sheet. EPA 816F19005 April 2020.

Images: “Graphic” by Top Energy Training