3900 BROADWAY BASE FILE 2016-01-01 MF Import

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL i ' S. Used to divert small scasonal streems away From construction. They have been used successfully i on culvert replacement and extension jobs. Large Oex pipe can be used on larger sheams during culvert removal,repair,or replacement. 6. Connected to existing down spouts and roof drains and used to diven water away from work I arcas during building renovation,demolition, and conswction projects. There ate now several commercially available collectors that arc attached to the pipe inlet and help j prevcnt erosion at the inlet Oesign and lnstallation Speci�cafions Size the pipe to convey the tlow. The capacity Cor temporary drains shall be su�cient to handle a pcak flow equal to l.6 times the 10-year, 1•hour time step flow indicated by an approved continuous runoff model. If a 15-minute (or less)rime step is used,no correction factar is required. 1. Usc care in clearing vegetated slopes for installation. 2. Reestablish cover immediately on areas disturbed by installation. 3. Use tcmporary drains on new cut or fill slopes. 4. Use diversion dikes or swales to collect water at the top of the slope. 5. Ensure that the entrance area is stable and lazge enough to direct flow into the pipe. 6. Dike material shall be compacted to 90 percent modified proctor to prevem piping of water I through the berm.The entrance azea is a common failure location. 7. 1'he entrance shall consist of a standazd ilared end section for culverts l2 inches and lazgcr with a I . � mioimum 6-inch metal toe plate!�!prevent runoff from undercutting the pipe inlet. The slope of ' the entrance shall be at least 3 percent. Sand bags may also be uscd at pipe entrances as a temporary measure. B. The soil around and under the pipe end entrance section shall 6e thoroughly compacted ta prevcnt undcrcutting. 9. The flazed inlet section shall bc securely connected to the slope drain and havc watertight connecting bands. 10. Slopc drain sections shall be secutely fastened together, fused orhave gasketed watcnight fittings, and shall be securely anchorcd into the soil. l 1. Thrust blocks should be installed anytime 90 degcce bends are utilized. Depen�ing on size of pipe and tlow,thcsc can bc conshucted with sand bags, straw bales stakcd in place,T-posts anJ wire,or ecology blocks. l2. Pipe nceds to bc sccurcd along its full Icngth to prevcnt movcment. This can bc donc with stcel 'f-posts and wire. A post is installed on cach side of thc pipc and t6c pipe is wircd to lhcm. T'his s6ould be done every 10 to 20 Cect of pipe length or so,depcnding on the size of tl�c pipc and quanrity of water to be diverted. ' 13. Intcrcepmr dikes shall be used to d'vect runoff into a slope drain. The hcight of thc dike shall be at Icast l foot higher at all poiNs than thc top of the inlet pipc. l4. The arca below the oudet must be stabilized with a riprap apron(sce BMP C209 Outlet Protection, for the appropriate ouNet material). l 5. If the pipe slopc drain is conveying sediment-laden water,dircct all Oows into the sediment trapping faciliry. Volume 1!—Construction Stormwafer Pollution Prevention 3-42