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,~ <br />B = critical width = 115 = 87.5 feet <br />2 2 <br />Thus, the subsidence profile function becomes: <br />S = 1(2 x 9.0 (1 - tanh (2x!8.75)) <br />7 <br /> <br />Using the following distances from the point of one-half <br />maximum subsidence, the subsidence at various points are <br />calculated: <br />;(ft.)I IS0 30 1 20 10 0 I -10 I -20 I . 30I -40I -60I -IOOI <br />.(f t.) ~ <br />.01 04 .54 ~ <br />1.25 ~ <br />1.82 257 3.48 4.50 5.51 6.42 7.18 7.75 8.46I 8.~ <br />• The subsidence profile has been plotted with original stream <br />channel on Exhibit ~. It is seen that if both seams are fully <br />extracted in this area, a nick in the stream channel will <br />occur just inside the western boundary of the permit area. <br />It is not felt that the nick in the channel will significantly <br />disrupt flow during a rainfall event. The grade of the strearR <br />bed will tend to erode the nick naturally, however, it is re- <br />cognized that this could cause unwanted erosion of the stream <br />alluvium in this location. <br />It is proposed that during full extraction of this area, the <br />stream channel will be surveyed and monitored to determine any <br />significant profile changes. If any changes are significant, <br />the company will bring necessary construction equipment to the <br />g <br />56'~ <br />D. H. EMLING COMPANY <br />