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• SEDCAD+ assisted desigrs of Ditches DWP-Wand DWP-E (Enclosures 5 and 6) parameters are summarized irs the <br />following table. <br />Table 7-1 Ditch Depth and Water Velocity <br />Description Depth (with Frceboazd) Allowable Velocity Design Velocity <br />Circumvential Ditch, DWP-W 0.7/ feet' 5.50 fps' 2.93 fps' <br />Circumvential Ditch, DWP-E 0.7! feet' S.SOfps' 2.93 fps' <br />' Enclosure S <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 dischazges 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 dischazges from the site, if constructed as proposed, would meet the effluent <br />SSp standards of 0.5 ml/I following a 10-year, 24-hour storm event. The pile would be protected from runoff of <br />a 100 yeaz, 24 hour storm event. <br />• SEDCAD+ demonstrations indicate that proposed work meets the criteria jor a Small Area Exemption. <br />CERTIFICATION <br />The proposed design is good engineering practice, and conclusions reached, based on [he <br />information provided, aze valid to the best of my knowledge. <br />• iTyfo~fCs,`~a1k~P.E <br />_ Colorado Registration Number 18378 <br />. ~~ Dale: /z pel" ~!'F~ _ <br />• <br />(Wes[ Elk Lone Pine Gulch Development Waste Pile SAE, 12 October 1995, Page 7 of 7) <br />