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Rule 4.05.3(7)(b) <br />10. With the existing configuration of the Pond F flume, the capacity is 54.54 CFS. The <br />proposed gob pile expansion will result in a peak flow of 54.47 CFS, near maximum capacity <br />of the flume, with insufficient freeboard. BRL will need to revise the design and propose a <br />larger flume to ensure that the required freeboard of 0.3' is maintained at peak discharge. <br />Rule 4.10.4(2) <br />11. BRL is proposing to excavate the ridge of material back to a slope of 1.5H: 1V. It is apparent, <br />from the contour lines shown on Figure 1, that coal mine waste (CMW) will be placed only <br />part way up the cut slope, and that a portion of the slope will remain permanently exposed. <br />TR -72 does not provide a prediction of the long -term stability of this slope. As referenced in <br />TR -44, Buckhorn Geotech determined that a cut slope of 2H: IV into the native soils (for <br />CMWDA No. 4) would provide a factor of safety of 1.50. Please address the question of <br />long -term stability of the permanent cut slope that appears to be proposed above the <br />placement level of the Coal Mine Waste. <br />If you have any questions, please contact me. <br />Sincerely, <br />4 <br />Brock F. Bowles <br />Environmental Protection Specialist <br />cc: William Bear, Bowie Resources, LLC <br />Page 13 <br />