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2.05.4(2)Icl <br />The Stripping Ratio Contour Map, Drawing No. 105, <br />can be used to determine if the mine area should be categorized <br />as having thin or thick overburden. The bulking factor for the <br />overburden and spoil is estimated to be 1.3. The following table <br />lists by stripping ratio the projected ratio of the final volume <br />to the initial volume. Initial volume is the sum of overburden <br />and coal volume prior to removal of coal. Final volume is the <br />product of the overburden volume times the bulking factor minus <br />the volume of the coal. <br />Stripping Ratio <br />1:1 <br />1.6:1 <br />2:1 <br />3:1 <br />3.3:1 <br />4:1 <br />5:1 <br />6:1 <br />7:1 <br />8:1 <br />12:1 <br />0.65 <br />0.80 <br />0.87 <br />0.98 <br />1.00 <br />1.04 <br />1.08 <br />1.11 <br />1.14 <br />1.16 <br />1.20 <br />• It can be seen that the only areas of thin over- <br />burden are in the areas along the outcrop. The maximum stripping <br />ratio in the mine area is 8:1 so there are no areas of the mine <br />that would be classified as thick overburden. <br />The final contours of the mining area are influ- <br />enced b,y the thickness of the coal seam, the overburden and the <br />bulking factor. The table presented in Exhibit 12 lists the <br />estimated change in the original surface elevation based on these <br />factors. The extremes occur when the coal is the maximum thick- <br />ness, 6.0'. The table shows that the final contours may be 4'. <br />higher than the original contours in areas where the coal is 6. <br />thick and the stripping ratio is 8:1. The other extreme is where <br />the coal is 6.0' thick and the str p.~ng ratio is 1:1. In these <br />areas the final contours may be 4.2 ower than the original{,JOB <br />contours. a <br />_ _ ~esL+W~~~M"P" <br />The table presented in Exhibit 12 is the bas~is`~~for <br />the nrenaration of the final contour man. Final eradin¢ will be <br />done so the final topographic conT"igura <br />nearly the same as the postmining topogr <br />has been completed and the spoil tested <br />in accordance with Section 2.05.3(6), the <br />able for topsoil placement. <br />Ratio <br />Final Volume/Initial Volume <br />chic configuration shown <br />0. After final grading <br />for subsoil suitability <br />regraded area is avail- <br /> <br />. 2.05-22 May 1991 <br />