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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 extending above the surface shall be removed to <br />about 2 or 3 inches above the surface. An identification cap will be grouted in the top of the <br />remaining casing. This permanent sealing method for drill holes is essentially the same as shown <br />on Figure V-2 of the permit with the exception that the remaining casing and ID cap serve as the <br />permanent hole marker. <br />Sloping ventilation shafts and portal entries will be plugged by one of two approved methods <br />(Section 4.07.3). The first method utilizes an unreinforced wall of concrete, bricks, the or concrete <br />block 2 feet thick or greater, The second method is to backfill the opening with incombustible <br />material for a distance of ai 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 <br />the Ventilation Area entries at the face is appro>mately 5380 feet. The estimated 50 year flood <br />level is 5372 feet, the 100 year flood is 5373, and the 500 year flood is 5375 feet. All of the <br />proposed entries are above the 50 year, 100 year and 500 year floods, therefore no surface water <br />is likely to enter the mine entries. Also the sealing method proposed for the sloped entries will <br />• prevent any significant amounts of water from entering the mine after abandonment (Estimated <br />flood levels from the U.S. Army Corps of Engineers, Sacramento, California). The B-Seam <br />ventilation shaft opening was found to be well above the flood line of the Scullion Gulch during an <br />inspection by Mr. Dan Mathews, DMG ReGamation Spedalist. <br />Vertical shafts will be filled for the entire depth of the shaft and, for the first 50 feet from the bottom <br />of the coalbed, the fill shall consist of incombustible material. Surface facility demolition rubble may <br />be used for fill if suitable and available. Coal refuse may be used above the first 50 feet from the <br />bottom of the coalbed. The top of the hole will then be filled with a plug of concrete at least 6 inches <br />thick. The concrete plug will have a 2-inch diameter vent pipe extending at least 15 feet above the <br />surface of the shaft. See Figure V-2. All vertical shaft openings will be above any possible flood <br />levels and will not be located near any surface runoff watercourses. This plan applies to the B- <br />Seam ventilation 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 <br />major mine ventilation system. <br />All openings large enough for human access required for monitoring or for ventilation purposes <br />which are located in areas without controlled access will be covered by a grate and screen set in a <br />frame of steel or concrete. The grate shall be locked or secured at all times to prevent <br />unauthorized entry. The details of the frame, grate, and screen are subject to the approval of the <br />appropriate regulatory authooties. These openings will be inspected at periodic intervals to verify <br />• <br />MR 126 (4/2004) V-18 <br />