17 E MARINE VIEW DR 2022-02-01 - Laserfiche WebLink

. May be used as a permanent diversion channel to cant' the runoff. . Sub -basin tributary area should be one acre or less. . Design capacity for the peak volumetric flow rate calculated using a 10-minute time step from a 10-year, 24-hour storm, assuming a Type 1A rainfall distribution, for temporary facilities. Alternatively, use 1.6 times the 1 0-year, 1 -hour flow indicated by an approved continuous runoff model. For facilities that will also serve on a per- manent basis, consult the local government's drainage requirements. Interceptor dikes shall meet the following criteria: . Top Width: 2 feet minimum. . Height: 1.5 feet minimum on berm. . Side Slope: 2H:lV orflatter. . Grade: Depends on topography, however, dike system minimum is 0.5%, and max- imum is 1 %. . Compaction: Minimum of 90 percent ASTM D698 standard proctor. . Horizontal Spacing of Interceptor Dikes: Average Slope Slope Percent Flowpath Length 20H:l V or less 3-5% 300 feet (10 to 20)H:lV 5-10% 200 feet (4 to 10)H:1V 10-25% 100 feet (2 to 4)H:1 V 25-50% 150 feet • Stabilization: depends on velocity and reach . Slopes <5%: Seed and mulch applied within 5 days of dike construction (see BMP C121: Mulching (p.284)). . Slopes 5 - 40%: Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion. . The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall occur at the outlet. Provide energy dissipation measures as neces- sary. Sediment -laden runoff must be released through a sediment trapping facility. . Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. Interceptor swales shall meet the following criteria: . Bottom Width: 2 feet minimum; the cross-section bottom shall be level. Depth: 1-foot minimum. 2014 Stormwater Management Manual for Westem Washington Volume 11 - Chapter 4 - Page 332