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3. Geolocrv and Mineral Resources <br />• Direct Impacts- Evidence of subsidence fractures <br />was noted on National King Coal's Federal lease <br />P-058300 in 1980 during the process of preparing <br />the Environmental Assessment for Emergency Coal <br />Lease C-29125. The fractures were observed in an <br />area approximately 300 feet north of the emergency <br />lease. boundary and on the east limb of Federal <br />lease P-058300. The area of subsidence is above <br />the western edge of the pillars that were extracted <br />in the King Coal Mine in 1979. <br /> A condition of approval of National King Coal's <br /> mine permit revision for Lease C-29125 by Colorado <br /> Division of Minerals and Geology was that <br />i <br />' subsidence would be monitored on a quarterly basis. <br /> The monitoring was initiated to determine if any <br /> new subsidence was occurring. The last report of <br /> November, 1990 by Cliff Schmid, Registered Land <br /> Surveyor and Fred M. Johnson, Certified Geologist <br /> indicated that no evidence of new subsidence <br /> existed. National King Coal continues to monitor <br /> for subsidence effects on a quarterly basis. Some <br /> monitoring is also performed periodically by the <br /> various regulating agencies (OSM and CDMG). <br />• The above evidence suggests that subsidence could <br /> occur due to extraction of the 4.5 to 5.7-foot coal <br /> seam and pillars on retreat in the proposed lease <br /> area. Although a maximum subsidence of 6 feet <br /> could occur, the most likely showing on the surface <br /> would be tension cracks such as the ones identified <br /> on Federal lease P-058300. in addition, as a <br /> result of the requirement for the quarterly <br /> monitoring of the mine for subsidence and the <br /> greater thickness of overburden, it is not <br /> anticipated that subsidence will be evidenced to <br /> the degree that was noted on Federal lease <br /> P-058300. <br />Subsidence fractures could allow the escape of <br />methane gas to the surface and could increase the <br />hazard of underground and surface fires. Although <br />this is not likely due to the low liberation of <br />methane of the Menefee coal (less than 1~), the <br />potential of causing surface impacts is present. <br />12 <br />• <br />