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4. Culvert Designs <br />Culverts C 101 through C 133 have been designed using the corrugated metal type, with a <br />Manning's n of 0.024, slopes of 1.5% and peak flows of 10, 25 or 100 year return intervals, <br />depending upon the life of the structure. Standard Federal Highway Administration techniques <br />were used to size the culverts in all locations. Culverts mitered to conform to the slope used a Ke <br />of 0.70, although culverts projecting from fill for the HW/D ratios used here also produce almost <br />the same results. The data on the following pages shows the designs for 12", 13", 16", 1811, 2411 <br />, <br />30", 36", 42" and 48" CMP's. Along the BB Road detour, 13" and 18" CMP's were used as <br />drainage culverts for the road. These do not have any significant drainage basins since Ditch C1 <br />parallels the road on the south side and captures any significant runoff that would normally drain <br />to the road. For this reason, the capacity of these culverts far exceeds any peak flows that could <br />occur in the minor basins and no designs are shown for these culverts (Culverts C 119-C 124). <br />The allowed height of water above each culvert is shown on each of the following charts (from <br />FHA), which are used in determining the headwater to diameter ratio (HW/D) and consequently, <br />the capacity of the culvert. <br />Many culverts have the same basin designs as ditches described earlier. If this is the case, no <br />new design is shown, the table simply refers to that ditch design. <br />Given the above parameters, the following pages show the capacities of the culverts as follows: <br />12" <br />4.2 cfs <br />13" <br />5.1 cfs <br />16" <br />8.4 cfs <br />18" <br />11.2 cfs <br />24" <br />18.1 cfs <br />30" <br />32.1 cfs <br />36" <br />50.0 cfs <br />42" <br />74.1 cfs <br />48" <br />102.7 cfs <br />Culverts C 13 0 through C176 have been designed using a variety of methods including SEDCAD <br />and HydroCAD and the results of these designs have been provided either on the following <br />pages or in other sections of the PAP. Since these culverts have been designed using various <br />programs and methodologies than culverts C 101 through C 129, their summary information has <br />been provided in a separate Table 2.05.3(3)-3, Culverts C130 -C176. Although culverts C130-133 <br />has been previously approved, those culverts have been removed and their numbers used again in <br />the locations shown on Map 2.05.3(3)-1. <br />Attachment 2.05.3(3)-1 Page 25 March 2016 (TR -70) <br />