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3. Geologic Information and Raise Bore Drilling <br />The raise to provide the escapeway and ventilation for the mine is an 8.0 feet diameter hole that is <br />constructed by first drilling a pilot hole from the surface of approximately 8 -14 inches in diameter into <br />the underground workings. A 13 inch diameter pilot hole was used for the Virginius raise bore. A large 8 <br />feet diameter bit is then brought into the mine and attached to the end of the solid steel pipe at the end <br />of the pilot hole. This bit is then rotated upwards from the surface rig, allowing the cuttings to fall by <br />gravity back into the mine workings. See Figure 1 below for a conceptual illustration of this process. <br />A 7 02 <br />Figure 1- Raise Bore Process <br />Item 1 of the above Figure 1 shows the pilot hole being drilled from the surface. Item 2 shows the drill <br />bit attached and the cuttings being dropped into the mine workings, where they are "mucked out" and <br />brought outside for permanent placement in the designed embankment at the mine. Item 3 shows the <br />raise bore completed and the cuttings at the bottom. In the case of the Revenue site, the raise bore is <br />approximately 1800 feet deep. <br />Page 5 of 17 <br />