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Brock Bowles <br />BOW - 2: Please see new Section E - E' on Figure 1. <br />- 3 - May 22,2012 <br />ground surface, the limits of excavation proposed, any CMW that is presently in- place, and the <br />proposed final limits of CMW placement. <br />Rule 4.05.6(3)(a) <br />7. DRMS: The revised Sedcad modeling provided by Bowie Resources, LLC (BRL) indicates that <br />the additional disturbance created with the gob pile expansion will result in increased runoff to <br />Pond F. Accordingly, the sediment storage of the pond must be reduced by half to accommodate <br />the additional runoff volume. BRL has revised the model assuming there will be one year of <br />sediment storage, down from the original plan for two years' storage. In reviewing the quarterly <br />sediment pond reports provided by BRL since Pond F was constructed, BRL has reached the <br />maximum sediment capacity and been required to clean Pond F annually. If BRL increases the <br />disturbed area and subsequent runoff volume as predicted in the proposed gob pile expansion <br />plan, BRL would need to clean the pond on average every six months. The Division is concerned <br />that this increased frequency may not be manageable long term, and is inconsistent with Rule <br />4.05.6(3)(a), requiring " ... adequate sediment storage volume and periodic sediment removal to <br />effect compliance with Rule 4.05.2(7)." BRL should consider options for increasing the <br />volume of the pond. <br />BOW -2: Pond F has been revised. The escape ramp has been redesigned at a 3:1. Please see <br />revised page 4, and Figures 1, 2 & 3 and Maps 15 -3 & 21 -3. Rip rap will need to be <br />extended down into Pond F as the entrance point has been steepened. Rip rap was sized in <br />Excel for new Ditch F -7a, and will be the same as F7, 15 ". Please see revised page B -9 and <br />new page App. B -18i. <br />Rule 4.05.6(4) and 4.05.9(2) <br />8. DRMS: Page App. B -7, the flow characteristics for the Pond F Steel Flume, shows a side <br />slope of 1.5:1. The currently approved design shows a side slope of 0:1, which is consistent with <br />the currently installed flume. Please revise the design to reflect the existing side slopes <br />of 0:1. <br />BOW -2: Please see revised page App. B -7. <br />9. DRMS: Also on page App. B -7, the required peak discharge is listed as 35.52 CFS. The <br />Sedcad run shows a peak discharge of 54.47 CFS. Please also revise this figure to 54.47, as <br />shown in the Sedcad model output (page App. B -40). <br />BOW -2: Please see revised App. B -7. <br />Rule 4.05.3(7)(b) <br />10. DRMS: 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 of <br />the flume, with insufficient freeboard. BRL will need to revise the design and propose a larger <br />flume to ensure that the required freeboard of 0.3' is maintained at peak discharge. <br />