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West E!k Mine: Subsidence Evaluation of the Revised Mine Pane! ~avovlc in Section ?! and Sectinnv 11f and 27 Pave 3 • MODEL RESULTS After the key panel parameters were defined, the data were entered into the computer model, CISPM. CISPM uses the influence function method to predict surface subsidence resulting from longwall mining. Exhibit 60 of the Apache Rocks Permit Revision explained the method by which the model was calibrated to the West Elk Mine using data from the subsidence monitoring network. The model has shown the ability to accurately predict subsidence (vertical displacement) at the mine. This was demonstrated by calibrating the model using Panels 1NW and 2NW, then using the model to predict subsidence over Panels 3NW through 7NW. SECTION 21 PANELS A comparison of the vertical displacement resulting from the original and revised longwall panel layouts is shown in Figure 2. Panel 1NW is included to show the • influence of adjacent longwall panels. The maximum subsidence resulting from both panel layouts is approximately 8 feet with about 2.5 feet of subsidence occurring over the chain pillars. The only significant difference in the vertical displacement profiles is the result of mining only two panels in the revised layout as opposed to three, originally. As with vertical displacement, the maximum tilt and strain (Figures 3 and 4, respectively) corresponding to the original and revised panel layouts are nearly equal. Again, the third panel associated with the original configuration creates the only significant difference in the profiles. SECTIONS 26 AND 27 PANELS The southernmost panel in the Box Canyon lease tract was included in the model analyses to show the influence of adjacent longwall panels. In contrast to the Section 21 layouts, the revised panel layout has one more panel than the original layout. This is • Wng t aver EngtKerr. /nc 831.031.13