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Memo to Dave Berry <br />Bowie No. 2 Geotechnical Adequacy Responses <br />page 3 <br />be met during construction, BRL should propose an appropriate filter <br />fabric for approval by the Division, prior to installation. <br />68. As observed in #27, above, the Division cautions BRL that timing is <br />essential. Permit approval cannot occur until the geotechnical stability <br />of the proposed coal handling facilities has been demonstrated to the <br />satisfaction of the Division. <br />69. BRL's response to this item is acceptable. While the Division continues to <br />be concerned regarding the potential implications of slope instability and <br />soil expansion for the majority of the site, the applicant should- be able to <br />compensate for any untoward manifestations of rock fall or soil expansion <br />at the coal processing waste facility. <br />2.1 WESTEC clarified its observation that no surficial springs or signs of <br />ephemeral streams were noted within the footprint of the proposed waste <br />pile. Its observation was based partially upon J. E. Stover & Associates <br />observations conducted at the site throughout the previous year. Because <br />WESTEC has proposed the construction of an underdrain beneath the pile, <br />the Division will accept this second party observation concerning the <br />hydrology of the proposed coal processing waste pile site. <br />4.3.2 Slope Stability -Material Properties <br />The Division expressed a concern because WESTEC assumed material <br />properties for three of the four involved earthen materials in completing <br />its slope stability analysis for the proposed waste pile. Only strength <br />parameters for the coal waste, material "1" were determined by <br />performing a direct shear test in the laboratory. Strength parameters for <br />existing sandstone-derived colluvial material underlying the proposed <br />waste pile, material "2", were theoretically developed from <br />interpretation of the Standard Penetration Test (SPT) blow counts <br />recorded in the field. Strength parameters for the Mancos Shale bedrock, <br />material "3", were similarly deduced from SPT blow counts. Strength <br />parameters for the historic coal mine waste fill material located beneath <br />