2007-08-17_PERMIT FILE - C1981035 ‎(21)‎

• Permit No: C1981035
• IBM Index Class Name: PERMIT FILE
• Doc Date: 8/17/2007
• Doc Name: Environmental Assessments
• Section_Exhibit Name: KI Appendix 13
• Media Type: D
• Archive: No

• The only known mineral resource contained in the application area is coal. The coal deposits
occur within the Menefee Formation of the Cretaceous Mesa Verde Group and is within the
Durango Known Recoverable Coal Resource Area (KRCRA).
National King Coal is the only operating mine in the area at this time. There aze no known oil
and gas deposits in the proposed modification azea. However, oil and gas is known to occur in
the Point Lookout, Gallup, Dakota Sandstone and the Paradox Formations.
The proposed modification area is characterized by hilly plateau tops cut by one ephemeral
drainage. The elevation ranges from about 7,300 to 7,500. The geologic formation outcropping
in the area is the C1iffHouse Formation of the Cretaceous Mesa Verde Group and the overlying
Quaternary alluvial deposits. The coal proposed for mining is coal bed 1 in the Menefee
Formation that outcrops about 2 miles north ofthe proposed modification area in the Hay Gulch
drainage.
No quantitative data exists for subsidence on the proposed modification azea; however, the
surface effects of subsidence have been recorded on Federal leases P-058300, COC-29125 and
COC-49465 approximately 'h-mile north of the proposed modification area. The overburden
thickness ranges from 300 to 400 feet above coal bed 1 in the proposed modification area.
Subsidence is directly affected by the thickness of the coal seam mined (4 to 6 feet), the
overburden thickness, and overburden composition.
• A condition of approval of National King Coal's mine permit revision for Lease C-29125 and
subsequent permit revisions by Colorado Division of Minerals and Geology was that subsidence
would be monitored on a quarterly basis. The purpose of the monitoring was to determine if any
new subsidence was occurring and if the Huntington Ditch was being affected in any way.
According to National King Coal records (Second Quarter Monitoring, 1999), there are no new
subsistence cracks in the areas requiring monitoring. All areas, which lie above underground
support pillazs that have been removed, continue to be .monitored on a quarterly basis for
evidence of material damage to the surface.
Colorado Division of Minerals and Geology rules 2.05.6 and 4.20 require that "underground
mining activities shall be planned and conducted so as to prevent subsidence from causing
material damage to the surface." Material damage is defined in Rule 2.05.6 with respect to
subsidence as changes which prevent restoration of affected structures and with respect to
renewable resource lands; changes which disrupt an aquifer, or a rechazge azea to an aquifer,
which serves as a beneficial use of water; or changes which prevent restoration of productivity
for agricultural lands.
There are no active faults adjacent to or on the proposed modification area (Zapp, 1949). No
other geologic hazards aze known to exist.
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