In situ uranium mining is a method of mining used to obtain uranium that is deep underground. Dissolving solutions are injected into the uranium deposit to allow the uranium to flow more freely, allowing it to be pumped up through a system of wells to the ground above where it can be processed. When uranium ore is deep underground, removing the overlying rock can be extremely difficult and very expensive. Not removing the overlying rock has several advantages. In situ mining causes considerably less environmental disturbance at the surface. It also reduces the potential for radiation exposure by keeping the uranium contained underground. In situ mining is more economical for mining lesser quality uranium ore than surface mining is, since the costs of stripping away the overburden is not incurred. See uranium mining for other methods of attaining uranium.
The following video (from Cameco, a uranium mining company) shows how the in situ uranium mining process works.