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 Class | Number of Injection Wells | Injection Wells Inspected |
---|---|---|
Class I | 830 | 453 |
Class II | 181,431 | 84,317 |
Class III | 28,327 | 406 |
Class IV | 122 | 27 |
Class V | 531,176 | 4,038 |
Class VI | 2 | 0 |
Source: EPA2

Citations
1. USEPA. (2022, July 22). Class III injection wells for solution mining. Retrieved 12/30/2022 from https://www.epa.gov/uic/class-iii-injection-wells-solution-mining.
2. USEPA. (2020). Underground Injection Control Program Fact Sheet. EPA 816F19005 April 2020.
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