1710 W MARINE VIEW DR 2024-01-03

. When outlet velocities exceed those allowable for the receiving stream, outlet protection must be provided. Maintenance Standards Subsurface drains shall be checked periodically to ensure that they are free -flowing and not dogged with sediment or roots. . The outlet shall be kept dean and free of debris. • Surface inlets shall be kept open and free of sediment and other debris. . Trees located too close to a subsurface drain often dog the system with their roots. If a drain becomes cogged, relocate the drain or remove the trees as a last resort. Drain placement should be planned to minimize this problem. . Where drains are crossed by heavy vehicles, the line shall be checked to ensure that it is not crushed. BMP C206: Level Spreader Purpose The purpose of a level spreader as a Construction Stormwater BMP is to provide a temporary outlet for dikes and diversions and convert concentrated runoff to sheet flow prior to releasing it to sta- bilized areas. Conditions of Use Use level spreaders when a concentrated flow of water needs to be dispersed over a large area with existing stable vegetation. Use only where the slopes are gentle, the water volume is relatively low, and the soil will adsorb most of the low flow events. Items to consider are: . What is the risk of erosion or damage if the flow becomes concentrated? . Is an easement required if discharged to adjoining property? Design and Installation Specifications • Use above undisturbed areas that are stabilized by existing vegetation. . Discharge area below the outlet must be uniform with a slope flatter than 5H :1 V. . Do not allow any low points in the level spreader. If the level spreader has any low points, flow will concentrate, create channels and may cause erosion. . Ensure the outlet is level in a stable, undisturbed soil profile (not on fill). 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 347