1710 W MARINE VIEW DR 2024-01-03

. The runoff shall not re -concentrate on site after release from the level spreader unless it is intercepted by another downstream measure. . The grade of the channel for the last 20 feet of the dike or interceptor entering the level spreader shall be less than or equal to 1 percent. The grade of the level spreader shall be 0 percent to ensure uniform spreading of runoff. . A 6-inch high gravel berm placed across the level lip shall consist of washed crushed rock, 2- to 4-inch or 3/4-inch to 1'/:-inch size. . The spreader length shall be determined by calculating the peak volumetric flow rate using a 10-minute time step from a Type 1 A,10-year, 24-hour design storm. The length of the spreader shall be a minimum of 15 feet for 0.1 cfs and shall increase by 10 feet for each 0.1 cfs thereafter to a maximum of 0.5 cls per spreader. Use multiple spreaders for higher flows. . The width of the approach to the spreader should be at least 6 feet. . The depth of the spreader as measured from the lip should be at least 6 inches and it should be uniform across the entire length. . Level spreaders shall be set back from the property line unless there is an easement for flow. . Materials that can be used for level spreaders include sand bags, lumber, logs, concrete, pipe, and capped perforated pipe. To function properly, the material needs to be installed level and on contour. See Figure II-3.14: Cross Section of Level Spreader and Figure 11-3.15: Detail of Level Spreader. Maintenance Standards The level spreader should be inspected during and after runoff events to ensure that it is functioning correctly. . The contractor should avoid the placement of any material on the level spreader, and should prevent construction traffic from crossing over the level spreader. . If the level spreader is damaged by construction traffic, it shall be immediately repaired. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 348