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floors. An alluvial valley floor may exist south of the application area in Hay Gulch. It is not <br />anticipated that mining in the azea will affect the possible alluvial valley floor at Hay Gulch. <br />GEOLOGY AND MINERAL RESOURCES <br />The only known mineral resource contained in the project azea is coal. The coal deposits occur <br />within the Menefee Formation of the Cretaceous Mesa Verde Group and is within the Durango <br />Known Recoverable Coal Resource Area (KRCRA). <br />National King Coal is the only operating mine in the azea at this time. There are no known oil and <br />gas deposits (NKOGD) in the proposed project azea. However, oil and gas is known to occur in the <br />Point Lookout, Gallup, Dakota Sandstone and the Paradox Formations in other Southwestern <br />Colorado locations.. <br />The proposedprojectazeaischaracterizedbyhillyplateautopscutbytwoephemeraldrainages. The <br />elevation ranges from about 7,300 to 8,200 feet. The geologic formations outcropping in the azea <br />are the Cliff House Formation of the Cretaceous Mesa Verde Group and the overlying Quaternary <br />alluvial deposits. The coal proposed for ruining is coal bed I in the Menefee Formation which <br />outcrops along the northwest boundary of the proposed lease area in the East Alkali Gulch drainage <br />and also to the southeast along an un-named gulch ("No Name GuIch'~. <br />No quanfitative data exists for subsidence on the proposed pmject azea; however, the surface effects <br />of subsidence have been recorded on Federal leases P-058300, C-29125, and COC 49465 <br />• approximately one mile south of the proposed project azea. The overburden thickness consistently <br />ranges from 300 to 400 feet above coal bed 1 throughout the area of the existing leases as well as <br />in the proposed lease area. Subsidence is directly affected by the thickness of the coal seam mined <br />(4.5 to 7 feet), the overburden thickness, and overburden composition. Subsidence will show as <br />stress cracks up to a couple of inches wide. <br />A condition of approval of National King Coal's mine permit revision for Lease C-29125 and <br />subsequent permit revisions by Colorado Division of Minerals and Geology was that subsidence <br />would be monitored on a quarterly basis. The purpose of the monitoring was to determine if any new <br />subsidence was occurring and if the Huntington Ditch was being affected in any way. According to <br />National King Coal records (Second Quarter Monitoring,1999),thereare nonew subsistence cracks <br />in the areas requiring monitoring to date. All areas, which lie above underground support pillars that <br />have been removed, continue to be monitored on a quarterly basis for evidence of material damage <br />to the surface. <br />Colorado Division ofitilinerals and Geology rules 2.05.6 and 4.20 require that "underground mining <br />activities shaii be planned and conducted so as to prevent subsidence ii-om causing material damage <br />to 't,re surface-" A4ateral damage is defineu in Rule 2.05.6 with respect to subsidence as changes <br />which prevent restoration of affected structures and with respect to renewable resource lands; <br />changes which dismpt an aquifer, or a rechazge azea to an aquifer, which serves as a beneficial use <br />:, .. ..,,g "-Ch yr° ..S or3^. n v. pi^v ..:'r:i i.^•i a~~.^.lll ~ 4: a2^^.vS. <br />There aze no active faults adj scent to or on the proj ect azea (Zapp, 1949). No other geologic hazards <br />