STANDARD FOR RIPRAP AND CONDUIT OUTLET PROTECTION HOW MUCH OF A DIFFERENCE DOES THIS CHANGE MAKE ? Lets look at an example: Q25 = 20.00 cfs, WO = 24 Inch or 2.00 ft. TW = 0.2 x DO =0.2 x 2.0 ft.= 0.40 ft., q =20.00 cfs / 2.00 ft. = 10.00 sfs Old Equation: D50 = 0.016 x q1.33 =0.016 x 10.001.33 = 0.855 ft. TW 0.40 ft. New Equation: D50 = 0.020 x q1.33 =0.020 x 10.001.33 = 1.069 ft. TW 0.40 ft. 1.069 ft. = 1.25 = 25% Increase in D50 0.855 ft. PREFORMED SCOUR HOLE SECTION HAS BEEN REARRANGED TO “FLOW” MORE LOGICALLY HORIZONTAL APRON SECTION HAS BEEN REARRANGED TO “FLOW” MORE LOGICALLY 0.5 DO ISHBASH CURVE – CHANNEL RIPRAP ISHBASH EQUATION Vc is not the velocity correlated with Minimum Specific Energy ! FIGURE TS14C–6 GRAPHICAL SOLUTION FOR ISBASH TECHNIQUE FOR DIFFERENT STONE DENSITY DIFFERENT STONE DENSITY AVAILABLE FOR VERY HIGH VELOCITY CIRCUMSTANCES LANE METHOD – CHANNEL RIPRAP RIPRAP QUESTIONS ?