3535 RIVERFRONT BLVD 2023-02-21 - Laserfiche WebLink

vent sediment from entering the system until completion of landscaping. Provide 18- inches of sod around each finished lawn and yard drain. Table II-4.2.2 Storm Drain Inlet Protection (p.358) lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high fre- quency of maintenance. Limit drainage areas to one acre or less. Possibly provide emer- gency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Table II-4.2.2 Storm Drain Inlet Protection Type of Inlet Emergency Applicable for Protection Overflow Paved/ Earthen Conditions of Use Surfaces Drop Inlet Protection Excavated drop Yes, tem- Applicable for heavy flows. Easy inlet protection porary flood- Earthen to maintain. Large area Require- ing will occur ment: 30'x30'/acre Block and gravel drop inlet Yes Paved or Earthen Applicable for heavy concentrated protection flows. Will not pond. Gravel and wire Applicable for heavy concentrated drop inlet pro- No flows. Will pond. Can withstand tection traffic. Catch basin fil- Yes Paved or Earthen Frequent Maintenance required. ters Curb Inlet Protection Curb inlet pro- Small capacity Used for sturdy, more compact tection with overflow Paved installation. wooden weir Block and gravel curb inlet Yes Paved Sturdy, but limited filtration. protection Culvert Inlet Protection Culvert inlet Sed- iment trap 18 month expected life. Design and Installation Specifications Excavated Drop Inlet Protection -An excavated impoundment around the storm drain. Sediment settles out of the stormwater prior to entering the storm drain. 2014 Stormwater Management Manual for Western Washington Volume Il- Chapter 4 -Page 358