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CtTY OF EVERETT STORMWATER MANAGEIAENT MANUAL <br /> o Sfoper S m 40 percenr: Dependent om m�off velocides and dike meterieis. � <br /> Slabilitation shauld be done immcdiately using either sod or riprap or other <br /> measures to avoid erosion. <br /> h. 'fhe upslope sidc of thc dike shall provide positive urainage to lhe dike outlet. No <br /> erosion s6a11 occur at the outleL Provide eoergy dissipation measures az necesse�}'. <br /> Sediment-laden ruaoff must be released through a scdiment trapping faciliry. <br /> i. Minimize conshuction traffic over temporary dikes. Usr temporary cross culverts for <br /> channel crossing. <br /> 9. lnterceptor swales shall mect the following criteria; <br /> a. Bottom Width = 2 feet minimum; the bonom shall bc level <br /> b. Depth = I-Caot minimum <br /> c. Side Slope = 2:1 or flatter <br /> d. Grade = Meximum 5 percer.t, with positive drainage to a suitable outlet(such as a <br /> sediment pond) <br /> c. Stabilization = Seed as per BMP CI20, Temporary and Permanen(Seeding,or BMP <br /> C�01, Channel Lining, l2 iuches thick of riprap pressed into t6e bank and extending at <br /> least 8 inches vertical from the bottom. <br /> 10. inspect diversion dikes and interceptor swales once a week and after every rain[all. immediately <br /> remove sediment from the flow area. <br /> 1 I. Damage caused by conswetion traffic or other aciivity must be repaiced before the end of each <br /> working day. <br /> 12. Check outicts and make timely repairs as needed to avoid gully formation. When the arca bclow <br /> the temporary diversion dike is pertnancntly stabilized,remove the dike and fill and stabilize thc <br /> channel ro blend with the oatural sudace. � <br /> 3.3.2 BMP C2Q1: Grass-Lined Channels <br /> Purpose <br /> Purpose is to providc a channel with a vegetative lining for conveyance of cunoft. <br /> Cond.':ions of Use <br /> This practice applies to construction sites where wnc:ntrated runoff needs to be contained tu prevent <br /> erosion or flooding. <br /> • When a vegetative lining can provide suFticient stability for the channel cross•section and at <br /> lotver velocities of water(normally dependent on grade). This mcans that the channel slopes arc <br /> generally less than 5 percent and space is available for a relatively largc cross-section. <br /> � T}7�ical uses include roadside ditches, channcls at property boundaries,oullets for diversions,and <br /> ot6cr channels and drainage ditches in low arcas. <br /> � Channcls that will be vegetated should be installed before major eatthwork and hydrosceded with <br /> a BFM. The vegetation should be well established(i.e., 75 percent cover)before water is allowed <br /> to flow in the ditch. With channels that will have high flows,crosion conVol blankcts should be <br /> installed ovet the hydrosecd. If vegetalion cannot be established from seed before water is <br /> allowed in the ditch,sod should be installed in the bottom of the ditch in lieu of hydromulch and <br /> blankets. <br /> Volume 11— Construction Stormwater Pollufion Pravenfion <br /> 3-37 <br />