3900 BROADWAY BASE FILE 2016-01-01 MF Import

CITY OF EVERETT STORMWATER MANACaEMENT MANUAL �} � 14. The tence posts shall be placed or driven a minimum of 18 inches. A minimum depth of 12 inches is allowed if tapsoil or other sofl subgrade soil is not present and a minimum deplh of 18 inches cannot be reached. Fence post dep�hs shall be increased by 6 inches if the fence is located on slopes of 3:1 or steeper and tLe slope is perpendiculu to the fence. If required post dept6s cannot be obtained,the posts shall be adequately sccured by bracing or guying to prevent overtuming of thc fence due to sediment loading. l5. Silt feoces shall be located on contour as much as possible,except at the ends of the fence,where the fence shall be tumed uphill such that the silt fence captures the runoff water and prevents water from tlowing around the end oFthe fence. 16. [f the fence must cross contours,with the excepdon of the ends of the fence,gravel check dams plaxd perpendicular to the back of thc fence shall be used to minimize concentrated flow and erosion along t6e back of the fence. The gravel check dems shall be approximately 1-foot deep at the back of the fence. It shall be continued perpeodiculaz to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. The gravel check dams shall consist of ccushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gtavel check darns shall be located every 10 feet along lhe fence w6ere the fence must cross contours. The slope of the fence line wherc conrours must be crossed shall no1 be steeper than 3:1. 17. Wood,steel or equivalent posts shall be used. Wood posts shall have minimum dimensions of 2 inches by 2 inches by 3 feet minimum Icngth,and shall be free of defects such as Irnots, splits, or gouges. Steel posts s6all consist of either size No. 6 rr.nforcement bar or lazger,ASTM A 120 steel pipe with a minimum diamater of 1-inch,U,'f, L,or C shapc stecl posts with a minimum weight of 1.35 pounds/feet or other sleel posls having equivalent strength and bending resistancc � to the post sizes listed. The spacing of the support posts s6a11 be a maximum of 6 feet. i i 8. Fence back-up support,if used,shall consist of steel wirc with a m�imum mesh spacing of 2 inches,or a prefabricated polymeric mesh. The strength of the w've or polymeric mesh shell be equivalcnt to or greater than 180 pounds grab tensilc shength. The polymeric mesh must bc as resistant to ultraviolet rediation as the geotexeile it supports. 19. The base of both end posts must be at least 2 to 4 inches above the top of the silt fence Fabric on the middle posls for ditch checks lo drain properly. Use a hand level or string level,if neccssary, to mark base poinls beforc inscallation. 20. Install posts 3 to 4 (eet apart in critical retention areas and 6 fcet apart in standard applications. Maintenance Standards 1. Any damage shall be repaired immediately. 2. If concentrated flows are evidcnt uphill of the fence,they must be inlercepted and conveyed to a sediment pond. 3. It is important to check the uphill side of the fence For signs oFthe fence clogging and acting as a bamer to flow and then causing channelization oC Rows parallel to the fence. lf this accurs, replace the fence or remove the trapped sediment. 4. Sediment deposits shall either be removed when the deposit reaches approximately onc-third thc height of the silt fence,o�a sccond silt fence shall be installed. 5. 1C thc filter fabnc(geotextile) has deteriorated due to ultraviolet breakdou�n, it shall be replaced. Volume II—Conshuction Stormwater Pollution Prevention 3-56