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• The peak runoff from a 10-year, 24-hour storm event was calculated using the SEDCAD4 <br />model. <br />• Culvert PM-11 was sized using the culvert utility subroutine; the calculated diameter can <br />then be compared against the existing pipe diameter to determine if a new culvert pipe <br />should be installed. <br />• Channel PM-4D was designed using the channel utility subroutine for an erodible soil <br />matrix. <br />o Channel material: regraded soil covered with Enkamat 7020 turf reinforcement mat <br />(TRM). <br />o Manning's n: 0.036 for a TRM with a flow depth in the range of 0 - 6 inches <br />(Austin, D.N. and Williams, D.T., 1995, Computer-Aided Design of Grassed Inland <br />Waterways Using Permanent Geosynthetic Reinforcement Mattings, in Carrying the <br />Torch for Erosion Control: An Olympic Task, Proceedings of Conference 23, <br />February 25 -March 3, 1995, International Erosion Control Association, p.137- <br />146) as modified from (Chen, Y. H, and Cotton, B.A., 1988, Design of Roadside <br />Channels with Flexible Linings, Hydraulic Engineering Circulaz No. 15, Federal <br />Highway Administration, Publication No. FHWA-IP-87-7). <br />o Permissible velocity: 14 fps: (www.colbond-usa.com, 2006, Enkamat Technical <br />Specifications, 7020 Spec.pd,~. <br /> <br />TR-55 20-B.B-3 Revised 12/06 <br />