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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-1 of the permit with the exception that the remaining casing and ID cap serve as the <br />permanent hale marker. <br />Sloping ventilation shafts and portal entries will be plugged with an unreinforced wall of concrete 2 <br />feet thick or greater. The concrete will be poured in the space between two bulkheads consisting of <br />8-inch concrete blocks or other approved materials. Prior to plugging, the tunnel will be filled with <br />incombustible material for a distance of at least 25 feet from the mouth (Section 4.07.3). See <br />Figure V-2. <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 approximately 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 Reclamation Specialist. <br />Vertical shafts will be filled for the entire depth of the shaft with incombustible rubble from the <br />demolition of surface facilities. The top of the hole will then be filled with a plug of concrete at least <br />6 inches thick. The concrete plug will have a 2-inch diameter vent pipe extending 15 feet above the <br />surface of the shaft. See Figure V-1. 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. <br />i <br />(Permit Renewal #3, 8199) V-20 <br />