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Subsidence Evaluation for the <br />Exhibit 60E Southern Panels, Apache Rocks West, & Sunset Trail Mining Areas Page 22 <br />5.7 Relation between Dynamic and Final Subsidence Deformations <br />Maximum dynamic tilt (change of slope) and horizontal tensile and compressive strain are <br />reportedly less above longwall mining panels than are the final tilt and strain values at panel <br />boundaries. Dynamic tilt and strain decrease, relative to final tilt and strain, as the rate of face <br />advance increases. <br />Dynamic tilt and strain reportedly decrease with increasing speed of longwall coal extraction (Peng <br />1992, p. 20-21). Based on observations in a West Virginia coal mine: <br />1. Maximum dynamic tilt decreased by an average of 42 percent (from 0.0024 to 0.0014) as <br />the mining face rate of movement increased from 10 to 40 feet per day; dynamic tilt <br />therefore decreased by 14 percent as the face rate of movement increased by 30 feet per <br />day. <br />2. Maximum dynamic tensile strain decreased by an average of 22.5 percent (from 0.0031 to <br />0.0024) as the mining face velocity increased from 10 to 40 feet per day; dynamic <br />horizontal tensile strain decreased by 7.5 percent as the face increased by 30 feet per day. <br />3. Maximum dynamic compressive strain decreased by an average of 48 percent (0.0062 to <br />0.0032) as the face velocity increased from 10 to 40 feet per day; dynamic horizontal <br />compressive strain decreased by 16 percent as the face increased by 30 feet per day. <br />5.8 Critical Extraction Width of Mining Panels <br />Critical extraction width (Wcr) is the width of mining panels necessary for maximum subsidence <br />to occur at a given overburden depth (d). Values for Wedd typically range from about 1.0 to 1.4, <br />with an average of about 1.2. Based on the subsidence development data for the 5th NW longwall <br />panel, the critical extraction width may be closer to the average value of 1.2 than 1.4 in the <br />Southern Panels, Apache Rocks West, and Sunset Trail mining areas (Figure 4). <br />5.9 Results of Computer Modeling <br />A computer software package was used to model the results of subsidence measurements at West <br />Elk Mine and to project subsidence in the Southern Panels, Apache Rocks West, and Sunset Trail <br />mining areas. The package used is entitled: "Surface Deformation Prediction System (SDPS)", <br />Version 6.2G developed by Department of Mining Engineering, University of Kentucky; <br />Department of Mining and Minerals Engineering, Virginia Polytechnic Institute and State <br />University. This program performed an influence function analysis and best fit of West Elk Mine <br />subsidence data. The fit between the data points and the influence function output from the model <br />is shown in Figure 6. Considering that there was some F -seam influence on the B -seam subsidence <br />data, the actual subsidence measurements and subsidence profiles predicted by the influence <br />function model compare favorably. <br />W WE further calibrated the computer model using subsidence monitoring data collected over E - <br />seam panels E1 to E3. While the model over predicted the subsidence over panel E1, the previous <br />calibration accurately predicted the subsidence along the Dry Fork survey points. Therefore, <br />831-032.816 Wright Water Engineers, Inc. <br />October 2018 <br />