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Bowie No. 2 Mine C 1996083 Technical Revision No. 84- Second Adequacy Review Page I I of 15 <br />coal mine waste. <br />Native Soil <br />Gob Pile #2 <br />• (TR -42) used Lambert (2003) results <br />Gob Pile #4 <br />• (TR -44) Gradation & Atterberg Limits (5 sets) from 2 foundation holes bored in 2006; <br />• (TR -64) Revised Effective Strength Parameters to 4' =34.0 deg, c' =100 psf <br />Gob Pile #3 <br />• (TR -45) Gradation & Atterberg Limits (8 sets) from 7 foundation holes drilled in Dec -2006 <br />• (TR -45) Unconsolidated-Und rained (UU) Shear Strength (3 sets) based on various confining pressures <br />• (TR -45) Effective Shear Strength Parameters (1 set) based on Consolidated-Und rained (CU) testing <br />Coal Mine Waste <br />Gob Pile #2 <br />• (TR -42) Gradation & Atterberg Limits (3); Specific Gravity (4); Standard Proctor (3) <br />• (TR -42) Unconsolidated - Undrained (UU) Shear Strength (5) <br />• (TR -42) Effective Shear Strength Parameters (3 sets) based on Consolidated - Undrained (CU) testing <br />Gob Pile #4 <br />• (TR -44) Unconsolidated - Undrained (UU) Shear Strength (6 new) <br />• (TR -64) Effective Shear Strength Parameters (3) revised from TR -42 values; evaluated sensitivity at 4' = 30, <br />32 and 34 degrees <br />Historically, the coal mine waste generated by BRL's prep plant has contained a significant percentage of fine <br />material, which in turn results in the waste product having an extremely high moisture content. On occasion <br />the material has been over - saturated, with a soupy consistency. It has been the practice of Bowie Resources, <br />LLC, to dump and temporarily stockpile this waste within the footprint of an approved gob pile. This allows <br />some of the excess moisture to drain away, by gravity. Often the material is worked, and reworked, by <br />excavators which turn the material over, move it from place to place, to free up more of the moisture and <br />expose it to the air. Ultimately, BRL blends the waste with dry coverfill (native soil), that has been salvaged <br />and stockpiled separately, in order to obtain a product with a moisture content that approaches the range <br />where compaction can successfully be achieved. <br />Aside from the ongoing compaction (moisture- density) testing that is conducted on the mixed material, there <br />appears to have been no laboratory analysis of the strength parameters of the coal mine waste / coverfill <br />blend. This is an issue that should be addressed, and remedied, if necessary. <br />CIRCES Cost Estimating Soffi are <br />