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.

Under the UIC Program, EPA and the states regulate more than 400,000 injection wells. Class III wells comprise 8 percent of the injection wells in the U.S.

Class III wells are used to recover salt, sulfur, or uranium. Operators of Class III injection wells can use either of the following safe and environmentally sound techniques to extract minerals from the ground:

Solution Mining: used primarily to extract salt and sulfur from underground fromations. Well operators inject water to extract salt and super-heated steam to melt and extract sulfur.

In Situ Leaching: commonly used to extract uranium, and in some instances gold and copper from the ground. A non-toxic chemical solution is circulated, which dissolves or "leaches" mineral particles from the sand grains in the ore body.

What is An Underground Injection Well?

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 injecition wells, but they are all similar in their basic function. The Federal UIC program has grouped injection wells into five categories.