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<br />TABLE A - IV <br />D -SEAM AUGER SPACING AND EXTRACTION RATIOS <br />(Auger C OR D Seam, not both) <br /> <br /> TYPE AND SIZE OF AUGER <br />Analysis Seam Factor of Safe , PeneVation and Overburden Conditions Circular 6 -Foot Diameter Circular 7 -Foot Diameter Rectan utar t 3 -Foot Width <br />Location Thickness Type Auger Bedrock Depth Spoil Depth W W/D Extraction W W/D Extraction W W/D Extraction <br /> ft Penetration ft max ft max ft in °h in % in (~_ <br />North Wall Variable <br />7 10.3 2.0 0 to 300 195 0 44 0.61 28.4 52 0.62 33.0 118 1 .00 54.2 <br /> 10.3 1.5 500 195 170 70 0.97 23.2 82 0.98 27.0 152 1.29 48.2 <br />West Wall Variable <br />6 10.3 2.0 0 to 300 195 0 44 0.61 28.4 52 0.62 33.0 116 1 .00 54.2 <br /> 10.3 1.5 500 380 0 90 1.25 20.3 106 1.26 23.6 195 1.66 42.3 <br />East Wall <br />8 10.3 2.0 0 to 300 365 0 218 3.03 11.4 254 3.02 13.3 470 4.00 23.7 <br /> 10.3 1.5 500 435 0 218 3.03 11.4 254 3.02 13.3 470 4.00 23.7 <br />NOTES: <br />1. Analysis Location, refer to Fig. A-2 <br />2. Factor of Safety conditions (average web stress). <br />Variable -Indicates overburden depth increases with depth of auger penetration (Fig. A-3). <br />- Factor of Safety is a minimum of 2.0 at face, and 1.5 at maximum auger penetration. <br />Uniform -Indicates uniform, maximum overburden depths were used, FS minimum of 2. <br />3. W -minimum web width recommended (in.). Minimum 42 in. for 6 ft, dia.; 48 in. for 7 h. dia.; and W/D > 1.0 for rectangular. <br />4. WjD indicates approximate width to height ration of web. Minimum Of 0.57 for circular and 1.0 for rectangular. <br />5, Circular extraction ratios were calculated based upon full seam thickness and exact auger diameter. <br />s. Rectangular extraction ratios were based upon an auger height equal to seam thickness minus 6 inches. <br />7. Between 300 and 500 foot auger penetration, interpolation can be used to detemine web width ._ _ _ _ <br />