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• SEDCAD+ assisted design of Ditches DWP -W and DWP -E (Enclosures S and 6) parameters are summarized in the <br />following table. <br />Table 7 -1 Ditch Depth and Water Velocity <br />Description i Depth (with Freeboard) Allowable Velocity <br />Design Velocity <br />Circumvential Ditch, DWP -W <br />0.71 feet` I <br />5.50 fps' <br />2.93 fps' <br />Circumvential Ditch, DWP -E <br />0.71 feet' j <br />5.50 fps' 2.93 fps <br />' Enclosure 5 <br />'- Enclosure 6 <br />8. PROPOSAL <br />Mountain Coal Company proposes to construct the development waste pile as described and to employ best <br />management practices to: 1) reduce sediment discharges off the pile to concentrations less than effluent standards, <br />and 2) to protect the pile. <br />9. CONCLUSIONS <br />The SEDCAD+ analyses indicate that discharges from the site, if constructed as proposed, would meet the effluent <br />SSp standards of 0.5 ml /1 following a 10 -year, 24 -hour storm event. The pile would be protected from runoff of <br />a 100 year, 24 hour storm event. <br />SEDCAD+ demonstrations indicate that proposed work meets the criteria for a Small Area Exemption. <br />CERTIFICATION <br />The proposed design is good engineering practice, and conclusions reached, based on the <br />information provided, are valid to the best of my knowledge. <br />B G. WaIX' P.E <br />Colorado Registration Number 18378 <br />Date: /z Oc7` /P rs — <br />(West Elk Lone Pine Gulch Development Waste Pile SAE, 12 October 1995, Page 7 of 7) <br />�, <br />