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The drill holes (including vent holes) will be plugged by placing a cement plug in the casing from a <br />depth of 10 feet to the surface. Excessive casing will be removed to about 2 or 3 inches above the <br />surface. An identification cap will be grouted in the top of the remaining casing. This permanent <br />sealing method for drill holes is shown on Figure V-2. If a drill hole is completed through an aquifer, <br />and that aquifer is not lost as a result of mining the plugging will be consistent with Rule 4.07.3(2). <br />Sloping ventilation shafts and portal entries will be plugged by one of iwo approved methods (Section <br />4.07.3). The first method utilizes an unreinforced wall of concrete, bricks, file or concrete block 2 feet <br />thick or greater. The second method is to backfill the opening with incombustible material for a <br />distance of at least 25 feet from the mouth. See Figure V-1. <br />All of the mine entries will be sloped in and the entry faces will be above all ground water levels, <br />therefore ground water cannot exit through the mine entries. The elevation of the bottom of the "D" <br />Portal entries at the face is approximately 5636 feet. The estimated 50 year flood level is 5629 feet, <br />the 100 year flood is 5630 feet, and the 500 year flood is 5632 feet. The elevation at the bottom of the <br />Ventilation Area entries at the face is approximately 5380 feet. The estimated 50 year flood level is <br />5372 feet, the 100 year flood is 5373, and the 500 year flood is 5375 feet. All of the proposed entries <br />are above the 50 year, 100 year and 500 year floods, therefore no surface water is likely to enter the <br />mine entries. Also the sealing method proposed for the sloped entries will prevent any significant <br />amounts of water from entering the mine after abandonment. (Estimated flood levels from the U.S. <br />Army Corps of Engineers, Sacramento, California). The B-Seam ventilation shaft opening was found <br />to be well above the flood line of the Scullion Gulch during an inspection by Mr. Dan Mathews, DMG <br />Reclamation Specialist. <br />Vertical shafts will be filled for the entire depth of the shaft and, for the first 50 feet from the bottom of <br />the coalbed, the fill shall consist of incombustible material. Surface facility demolition rubble may be <br />used for fill if suitable and available. Coal refuse may be used above the first 50 feet from the bottom <br />of the coalbed. The top of the hole will then be filled with a plug of concrete at least 6 inches thick. <br />The concrete plug will have a 2-inch diameter vent pipe extending at least 15 feet above the surface <br />of the shaft. See Figure V-2. All verticel shaft openings will be above any possible flood levels and <br />will not be located near any surface runoff watercourses. This plan applies to the B-Seam ventilation <br />shaft and other large diameter shafts. <br />A plan for mine sealing will be submitted to and approved by MSHA before the shutdown of any major <br />mine ventilation system. <br />All openings large enough for human access required for monitoring or for ventilation purposes which <br />are located in areas without controlled access will be covered by a grate and screen set in a frame of <br />steel or concrete. The grate shall be locked or secured at all times to prevent unauthorized entry. <br />The details of the frame, grate, and screen are subject to the approval of the appropriate regulatory <br />authorities. These openings will be inspected at periodic intervals to verify the condition of the <br />opening and the grating. The openings will be fenced and signs posted identifying the hazardous <br />nature of the openings. <br />Technical Revision #61 (6/2005) V-18 <br />