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• April 1989 <br />Based on tl~e inspection of the core logs, laboratory testing, review <br />of geologic studies and the calculation of RQD, the following <br />conclusions were drawn. <br />° Laboratory mechanical properties of intact samples are not sig- <br />nificantly different for the same strata type in the vicinity <br />of the three seams. <br />° The B seam depositional environment was very Uniform, while both <br />E and E seams were influenced by a member of sandstone channels. <br />° Rock quality is significantly higher for the B and E Seam strata <br />than for the F Seam strata; this is possibly due to tl~e <br />depositional uniformity of the B Seam and the higher depth for <br />the B and E seams. <br />° Overall rock quality and ground conditions are expected to im- <br />prove whe~i mining begins in the E and R seams. The B seam roof <br />is probably the most stable of all seams. Rib conditions for <br />the B and E seams, however, may be less stable due to higher <br />• mining height and increased depth of cover. <br />1 RQD is defined as the ratio of the aan of intact core pieces fair inches or <br />greater aver the nni let~gtli. Tile rock quality corresponding to the RQD value are <br />as follows: <br />u <br />RQD <br />(%) ROCK <br />QUALITY <br /> < 25 Very Poor <br />25 - 50 Poor <br />50 - 75 Fair <br />75 - 90 Good <br />90 - 100 Excellent <br />