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0 ' <br /> CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br /> 3. Clean energy dissipater if sediment builds up. <br /> 3.3.11 BMP C220: Storm Drain Inlet Protection <br /> Purpose is to prevent coarse sediment from entering drainage systems prior to permanent stabilization of lb <br /> the disturbed area. • <br /> Conditions of Use • <br /> For use where storm drain inlets are to be made operational before permanent stabilization of the • <br /> disturbed drainage area. Protection should be provided for all storm drain inlets downslope and within <br /> 500 feet of a disturbed or construction area,unless the runoff that enters the catch basin will be conveyed <br /> to a sediment pond or trap. Inlet protection may be used anywhere to protect the drainage system. It is <br /> likely that the drainage system will still require cleaning. • <br /> Table 3.9 lists several options for inlet protection. All of the methods for storm drain inlet protection are • <br /> prone to plugging and require a high frequency of maintenance. Drainage areas should be limited to • <br /> 1 acre or less. Emergency overflows may be required where stormwater ponding would cause a hazard. <br /> If an emergency overflow is provided,additional end-of-pipe treatment may be required. • <br /> Table 3.9 Storm Drain Inlet Protection 1111 <br /> i <br /> Applicable for • <br /> Emergency Paved/Earthen <br /> Type of Inlet Protection Overflow Surfaces Conditions of Use • <br /> Drop Inlet Protection <br /> Excavated drop inlet Yes, temporary Earthen Applicable for heavy flows. Easy <br /> 1111 <br /> protection flooding will to maintain. Large area <br /> occur Requirement: 30 x 30-feet/acre • <br /> Block and gravel drop inlet Yes Paved or Applicable for heavy concentrated • <br /> protection Earthen flows. Will not pond. <br /> Gravel and wire drop inlet No Applicable for heavy concentrated • <br /> protection flows. Will pond. Can withstand • <br /> traffic. <br /> IS <br /> Catch basin filters Yes Paved or Frequent maintenance required. <br /> Earthen <br /> Curb Inlet Protection • <br /> Curb inlet protection with a Small capacity Paved Used for sturdy, more compact • <br /> wooden weir overflow installation. <br /> Block and gravel curb inlet Yes Paved Sturdy, but limited filtration. <br /> protection I• <br /> Culvert Inlet Protection • <br /> Culvert inlet sediment trap 18 month expected life. <br /> • <br /> Design and Installation Specifications I. Excavated Drop Inlet Protection—An excavated impoundment around the storm drain. Sediment • <br /> settles out of the stormwater prior to entering the storm drain. • <br /> a. Depth 1 to 2 feet as measured from the crest of the inlet structure <br /> b. Side slopes of excavation no steeper than 2:1 • <br /> • <br /> Volume II—Construction Stormwater Pollution Prevention <br /> 3-49 <br />