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V. Sealing of Drilled Holes and Underground Openings <br />Information pertaining to the sealing of drill holes aryl portal and ventilation openings is <br />presented in Section 2.05 of the permit application. <br />All portal and ventilation entries will be permanently sealed by backfilling each opening <br />with underground development waste, common fill, and sediment from the two sediment <br />ponds for a distance of 50 feet from the entrance. Once backfilling its completed, each <br />entry will be collapsed with explosives. National King Coal has adequately demonstrated <br />that sufficient quantities of fill material exist on site to complete both portal and mine <br />bench backfilling activities. <br />A single drill hole currently exists at the mine site in Hay Gulch and is used as a water <br />well. The landowner has requested that this well remain open following permanent <br />cessation of operation. The Division previously agreed with this request and hereby <br />reaffirms this previous approval. Therefore, the drill hole is not required to be sealed. <br />(4.07). <br />VI. Use of Explosives <br />The King Coal Mine is an underground mining operation; as such, no surface blasting <br />will occur. National King Coal has a permit (No. 527-Renewal) from the Colorado <br />Division of Mines to store and use explosives for the underground operations. This <br />permit is renewed annually. As all blasting occurs underground, additional requirements <br />of this section are not applicable. (4.08). <br />VII. Coal Mine Waste <br />A. The Division has approved plans for use, construction and maintenance of a coal <br />mine waste disposal area. Details concerning the construction of the waste pile can <br />be found in appendix 7-(1) of the Permit document. The coal refuse will be mine <br />waste rock extracted over the life of the mine. The material is composed of dense, <br />medium grained sandstone with occasional shale and carbonaceous shale partings. <br />The waste bank is located east of the mine entrance, beginning just east of the shop <br />building and extending up the east side drainage approximately 900 feet. A limit <br />equilibrium static analyses was performed using effective stresses to assure long term <br />stability of the bank. A relatively flat 3h:ly slope is used for the face of the waste <br />pile. This analysis provided a range of factors of safety between 1.85 and2.74, well <br />above the required 1.5. An intercept channel was constructed at the top of the bank <br />to divert flow originating above it away from the bank and into the east side <br />drainage. Similarly, a channel was constructed at the bottom of the waste bank to <br />intercept runoff from the pile. An under drain system was constructed beneath fill <br />and drains into the east side drainage (4.04.8(3)). Coal processing waste will be <br />18 <br />