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Stream Channel Parameters <br />Exhibit SSA and Changes Due to Mining-Induced Subsidence Pege 7 <br />IMPACTS OF SUBSIDENCE ON STREAM CHANNELS <br />The projected subsidence under each of the 11 stream channels has been determined using the <br />output from the Comprehensive and Integrated Subsidence Prediction Model (CISPM), Version <br />2.0 (Department of Mining Engineering, College of Mineral & Energy Resources, West Virginia <br />University), as calibrated using site-specific subsidence data and as reviewed by Mr. Richazd <br />Dunnxd, recognized subsidence expert. Exhibit 60B presents a detailed discussion of the <br />subsidence evaluation performed by W WE and Mr. Dunrud <br />In utilizing the CISPM program, each stream channel reach was defined as to location by "X" <br />and "Y" coordinates. Channel slope changes along with the magnitude of the subsidence were <br />determined for relatively short stream lengths of approximately 100 feet or less. The results of <br />the computer modeling for all 12 of the potentially affected stream channels are shown in <br />• Table 4. The slope change, either positive or negative, was either added to or subtracted from the <br />existing channel thalweg slope as determined from computations based upon USGS topographic <br />maps with a contour interval of 40 feet. <br />Table 4 shows that the most significant changes will occur in the tributaries overlying the <br />southern portion of the mined permit azea where E Seam mining thickness is projected to be at a <br />maximum (14 feet). For these channels, the maximum changes in slope aze an increase of 2.5 <br />percent and a decrease of 2.5 percent. Since the pre-mining average slope of these channels <br />ranged from 8.5 percent to 19.5 percent, the slope changes due to subsidence do not create any <br />reaches with negative or flat slopes. Slope impacts magnitudes aze greatest in the lower reaches <br />of Basins 29 and 32, where the pre-mining slopes aze approximately 4.8 percent and 4.0 percent, <br />respectively. The pre- and post-mining profiles for Basins 29, 32 and 36, shown in Figures 15, <br />16, and 18 respectively, demonstrate that the overall channel slope is not significantly impacted <br />by subsidence. <br />Basins 5, 6, 26 and 31 generally overly mining panels with thicknesses ranging from 9 to 12 feet. <br />The subsidence from rnining in these azeas will result in changes in the slopes of the stream <br />B3Y-032.620 Weight Water Engineers, inc. <br />