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V-ditch 43 is a new ditch that traverses across contour at a gradient of approximately 5%. The <br />• contributing drainage area is 22.2 acres. The SEDCAD4 demonstration estimates the 10-year, <br />24-hour storm event will generate a peak run-off of 1.6 cfs. <br />V-ditch #4 is a new ditch that traverses across contour at a gradient of approximately 5%. The <br />contributing drainage area is 8.7 acres. The SEDCAD4 demonstration estimates the 10-year, <br />24-hour storm event will generate a peak run-off of 1.4 cfs. <br />V-ditch #5 is a new ditch that traverses across contour at a gradient of approximately 5%. The <br />contributing drainage area is 16.7 acres. The SEDCAD4 demonstration estimates the 10-year, <br />24-hour storm event will generate a peak run-off of 2.7 cfs. <br />PM-8 Area Channel Designs <br />The channel utility vegetated sub-routine was used to design the V-ditches. Channel roughness <br />was calculated by the model assuming that the channel is grass-lined. These designs also <br />assumed that the channel soils were highly erosive, which limits the allowable velocity and, <br />provides for a more conservative design, which SCC believes is appropriate in this instance. <br />Channel designs for the five V-ditches and SIIPM-8 are presented in Appendix B on pages 7- <br />12-163 through 7-12-180. <br />• 2.3 Culvert Designs <br />Table 7-12-3, Culvert Schedule, indicates the design and construction information for culverts that <br />will be retained as permanent, postmine structures. The location of each culvert is shown on Exhibit <br />7-19. Culvert designs are presented in Appendix C, Culvert Designs. <br />3.0 REFERENCES <br />Barfield, B.J., Warner, R.C., and C.T. Haan, (Barfield et al.), 1981. Applied Hydrology and <br />Sedimentology for Disturbed Areas. Oklahoma Technical Press, Stillwater, OK. 603p. <br />Colbond Inc., Product Specification Information, Enka, North Carolina 28728, www.colbond- <br />usa.com <br />Erosion Control Technical Council, 2006. Standard Specifications for Rolled Erosion Control <br />Products, St. Paul, Minnesota 55118, www.ectc.org <br />Greenfix America, Product Specification Information, Brawley, California 92227, <br />www.greenfix.com <br />. North American Green, Product Specification Information, Evansville, Indiana 47725, <br />www.nagreen.com <br />TR-51 7-12-IOA Revised 09/09