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April 1989 <br />• <br />TABLE 3.4.A.8 <br />SEAM SEQUEDICE FOR THE FIVE <br />AREAS USED IN THE DESIGN <br />Area Seam Sequence <br />I E-B <br />II B-E-F <br />III B-E-F <br />7V B-E-F <br />V E-F <br />• Although E Seam mining over portions of the C Seam (Bear Mine) showed <br />no stability impacts, it should be recognized that B Seam caving may <br />impact tl~e mitteabli].ity of the upper seams in some locations. The <br />subsidence it~vol.ved in full B Seam caving causes strains and <br />displacements in the upper seams which may induce fracturing and a <br />decrease itt 1'OC1L quality. This would be felt mostly in the E Seam due <br />to its proximity to the B Seam, and in areas with geologic weaknesses. <br />Since exper.iettce in an ascending mining sequence in t}te area is <br />limited to a small area in the F seam, instrumentation of the E and F <br />Seams will be considered when mining the B seam. <br />MECFIANICAL FROPERTIES <br />Mechanical properties of the coal seams and immediate roof atld floor <br />strata were evaluated by standard compressive and tensile strengt]t <br />testing of cores. Previous testing described by Rao (1983) <br />establis}ted range values, but t}te number of tests (mostly from the <br />coal seams and B roof and floor) were too small to establish an <br />adequate data base for the large Mt. Gunnison resource. The data base <br />was increased in this study to a more adequate statistical <br />representation for the roof and floor of the seams. Additional coal <br />testing will be done in the future concurrent with any drill hole <br />program. <br />• <br />