2010-01-25_PERMIT FILE - C1981044A (4)

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subsidence will be 7.5 feet. • Where the No. 6 Mine longwall mining undermines the No. 5 Mine "first mined" room-and-pillaz workings, maximum subsidence will be 10.5 feet, assuming failure of the No. 5 Mine "first mined" pillars. • Where the No. 6 Mine longwall mining undermines [he No. 5 Mine longwall workings, maximum subsidence will be 13.0 feet. • The average angle of draw will be 19 degrees. • Possible development of surface cracking where [he overburden is less than 500 feet thick and the soil cover is thin. The predicted maximum possible worst case subsidence for the various structures and renewable resource lands is summarized on Table 79, Maximum Predicted Worst Case Subsidence on Structures and Renewable Resource Lands. A summary of [he anticipated degree of subsidence impacts on structures and renewable resource lands is presented on Table 80, Anticipated Degree of Subsidence Impact on Structures and Renewable Resource Lands Based on Maximum Predicted Worst Case Subsidence. The following is a description of the worst possible consequences of subsidence on the structures and renewable resource lands identified on Table 78, Inventory of Structures and Renewable Resource Lands, which may occur as a result of mining in the planned permit area. Structures Mine Facilities (Not Undermined). The mine facilities located at or adjacent to the portal azeas for the No. 5, No. SA, and No. 9 Mines will not be undermined. Since these structures will not be undermined and aze outside the area of influence of surface subsidence resulting from the planned underground mining, they will not be impacted by subsidence. Mine Facilities (Presently Undermined). The mine facilities within the permit area that are presently undermined or that will be undermined are located over development entries (mains and submains) which are designed to remain stable for the life of the mine. These areas have been protected against subsidence darrtage by ensuring [hat sufficient coal has been left in-place as pillars to prevent subsidence in these areas. These facilities are located outside the surface extent of the planned mining. Therefore, there will be no subsidence impact on these structures. Mine Facilities (To Be Undermined). Mine facilities owned by both Trapper Mining, Inc. and the planned mining of the No. 5 and No. 6 Mines will undermine EC. The Trapper Mining, Inc. surface mine structures planned to be undermined includes reclaimed surface land. The reclaimed surface land is classified as wildlife habitat and grazing land. Experience gained by EC with the No. 5 Mine longwall panel indicates that the subsidence impact on the reclaimed surface land is minimal. Surface subsidence has not significantly impacted existing land use of the reclaimed land. Therefore, surface subsidence from the No. 6 Mine longwalling is not expected to significantly impact the existing land use of the reclaimed surface lands. In addition, mining induced subsidence is not expected to have any significant impact on existing topsoil stockpiles. However, a general lowering of the ground surface with grade changes and surface cracking may occur. Mining induced surface subsidence is not expected to significantly impact small stock ponds. However, there will probably be a general lowering of [he ground surface. The EC surface facilities that will be undermined during the 1998 - 2003 permit term include: (1) old shop and storage azea, (2) ponds SH-Pl and SH-P2 and associated ditches SH-D2 and SH-D3, (3) a rock dust tank, (4) contractor staging area, (5) storage and wood shop, and (6) Okie Plaza well. It is anticipated [hat subsidence effects may necessitate minor repairs to these facilities. A general lowering of the ground surface with slight grade changes Permit Revision 04-34 2.05-51 Revised 7/2/04