Laserfiche WebLink
n <br />In which, <br />RH horizontal radius of the channel centerline in feet. <br />~ - deflection angle of the horizontal curve in degrees. <br />(a tolerance of +10` is acceptable.) <br />B - bottom width of the channel in feet. <br />L - length of the channel crossing between two curves in <br />feet. <br />Lm - mearider length of two consecutive bends and crossings <br />in feet. <br />The banks of the minimum maintenance alignment channel should <br />be sloped back at a ratio of no less than 4 horizontal to 1 <br />vertical (4H:lV) except where riprap or riprap with vegetation <br />is used. In the riprap sections, the banks will be no steeper <br />than 2.SH:lV. Riprap or riprap with vegetation shall be used <br />to protect the banks on the outside of bends and shall be <br />continued into the downstream crossing for a distance of 450 <br />feet as shown on Figure 2.1. Riprap with vegetation may be <br />substituted for riprap alone, but may be required by District <br />or the County in aesthetically sensitive areas or where wild- <br />life habitat reestablishment is considered important. <br />Vegetation only may be used in areas where, due to hydraulic <br />conditions, riprap is not required. in the portions of channel <br />not requiring riprap bank protection as specified above, vege- <br />tation by itself may be used to protect banks above the 2-year <br />flood. Below the 2-year flood level, riprap or riprap with <br />vegetation shall be used. <br />An armor layer shall be provided at each crossing between chan- <br />nel bends. The armoring layer shall be no less than 18 inches <br />UD6FCD GRAVEL GUIDELINES 12/17/87 <br />2-3 <br />