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of draw. Slopes facing towards the mined-out area will result in larger angles of draw. At the present time, [he <br />influence of irregular topography on the angle of draw has yet to be quantified. <br />It is anticipated that the irregulaz topography in the permit azea will cause some vaziation in the angle of draw. This is <br />consistent with preliminary observations from the longwall subsidence monitoring area above the No. 5 Mine where <br />the steeper slope facing away from the gob area had a significantly reduced angle of draw. Three (3) draw angles <br />along monitoring lines, as shown on the Subsidence Monitoring Map (Map 31, were measured. The results of these <br />measurements are shown on Table 86, Draw Angle Versus Slope and Orientation. <br />A careful review and evaluation of the site-specific subsidence data and the site-specific geotechnical data determined <br />the predicted angle of draw for the No. 5 and No. 6 Mines. This data was compared with research data from York <br />Canyon, New Mexico (Gentry, Stewart, and King, 1981), Kemira Colliery, Australia, (Kapp, 1974), Paonia, Colorado <br />(Dunrud, 1976), and Utah (Allgaier, 1982; and SUFCO, Personal Communication, 1986). The geotechnical <br />environment in the permit is similar to that found throughout the EC Mine complex as well as the various coalfields <br />of the western United States. An angle of draw of 19° is predicted as a conservative average draw angle for the permit <br />area. <br />SUBSIDENCE CONTROL PLAN <br />EC has prepared this Subsidence Contro] Plan to outline the proposed measures that may be taken, if required, to <br />restore any affected structures or resource lands to their pre-subsidence condition. This section specifically addresses <br />the structures present in the permit area. The only renewable resource lands potentially impacted by subsidence are <br />the surface and subsurface water resources. The proposed mitigation measures for the surface and subsurface water <br />resources are discussed in Section 2.05.6, Mitigation of the Impacts of Mining Operations. <br />Mine Facilities (Presently Undermined) <br />The mine facilities in the permit area that are presently undermined include mine roads, power lines, water lines, the <br />railroad spur, the coal storage silo, and the coal transport facilities. These facilities are presently located over <br />development entries (mains and submains) which are designed to remain stable for the life of the mine. These areas <br />have been protected against subsidence damage by ensuring that sufficient coal was left in place to prevent subsidence <br />in the area. If subsidence was to occur and the structures or facilities were to be damaged, they will be repaired or <br />replaced a[ the option of EC. <br />Mine Facilities (To Be Undermined) <br />The mine facilities under which planned mining will take place include EC facilities as well as those of Trapper <br />Mining, Ina The EC surface facilities that will be undermined during the 1998 - 2003 permit term include: (1) old <br />shop and storage area, (2) ponds SH-Pl and SH-P2 and associated ditches SH-D2 and SH-D3, (3) a rock dust tank, (4) <br />contractor staging area, (5) storage and wood shop, and (6) Okie Plaza well It is anticipated that subsidence effects <br />may necessitate minor repairs to these facilities. A general lowering of the ground surface with grade changed and <br />minor cracking may occur. The old shop will be monitored, and if it becomes unsafe, it will be repaired or removed. <br />Pons SH-Pl and SH-P2 and ditches SH-D2 and SH-D3 will be monitored closely during subsidence. Pre- and post- <br />subsidence surveys and monthly inspections between surveys will be conducted. Any damage will be promptly <br />repaired. The rock dust tank is no longer in use so no effects are anticipated there. The tank will be monitored, and if <br />any safety concerns are identified, it will be repaired or removed. No facilities except an empty water tank are located <br />at the contractor staging area, so no effects are anticipated. The trailer at the storage and wood shop will be monitored <br />to insure that it does not become unsafe. The Olde Plaza well will not be undermined until a revision is approved by <br />the CDMG for elimination or replacement of this monitoring well. Surface mine facilities belonging to Trapper <br />Mining, Inc. include reclaimed surface land, topsoil stockpiles, and small stock ponds. <br />Permit Revision 04-34 2.05-63 Revised 7/2/04 <br />