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Steep Mountain Brush 0.006 <br />Yestern Yheatgrass 0.006 <br />Topsoil Removed 0.586 <br />Total <br />Yeighted Average CP = 71.8717 = 0.164 <br />438.55 <br />Based on vegetation type discussed in Tab 10. <br />Storece Cepacit <br />176.13 1.0568 <br />5.13 0.0308 <br />120.21 70.4431 <br /> <br />438.55 71.8717 <br />The storage capacity of Sediment Pond 009 was also analyzed using the SEDCAD computer <br />program. Results of the SEDCAD model show the storm runoff volume from the 10-year, <br />24-hour precipitation event to be 3.46 ac-ft. The ponding area is designed to store 3.01 <br />ac-ft of sediment. There will be no discharge through the emergency spillway during the <br />10-year, 24-hour storm event. In addition, there will be adequate freeboard (2.8 ft.) in <br />the emergency spillway to the top of embankment during the 25-year, 24-hour storm event. <br />Table 13-SA-6 is a summary of the designed storage capacity. <br />• TABLE 13-SA-6 <br />Design Storage Capacity Summary <br />Pond 009 <br />Capacity <br />Elevation Stave (AC.-Ft.) Description <br />7073.0 ~ 0 0.00 Bottom of Pond Excavation -~ <br />7087.9 8.9 3.0 f00X Sediment Storage <br />7086.3 13.3 7.4 Elevation of Principal Spillway <br />7086.8 13.7 8.0 10-Yr, 24-Hr. Peak Stage <br />7089.5 16.5 11.5 Crest of Emergency Spillway <br />7090.4 17.5 12.8 25-Yr., 24-Rr. Peak Stage <br />7093.2 20.2 17.3 Top of Embankment <br />Peabody does not anticipate any other inflow to the pond et this time. The principal <br />spillway will be nonclogging and will automatically dewater the ponding area to maintain <br />the design capacity for the runoff volume for a 10-year, 24-hour storm event. Any <br />• additional dewetering required will be done by pumping the water out of the pond end using <br />it for either dust suppression or transporting it to another pond for treatment, or <br />discharging the water according to the approved Colorado MPDES permit. <br />13-SA-8 Revised 08/17/92 <br />