931 BROADWAY TEUTSCH STUDENT HOUSING 2018-03-07

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL 14. The fence posts shall be placed or driven a minimum of 18 inches. A minimum depth of 12 inches is allowed if topsoil or other soft subgrade soil is not present and a minimum depth of 18 inches cannot be reached. Fence post depths shall be increased by 6 inches if the fence is located on slopes of 3:] or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained,the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. 15. Silt fences shall be located on contour as much as possible, except at the ends of the fence,where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 16. If the fence must cross contours, with the exception of the ends of the fence, gravel check dams . placed perpendicular to the back of the fence shall be used to �ninimize concentrated flow and erosion along the back of the fence. The gravel check dams shall be approximately 1-foot deep at ' the back ofi the fence. It shall be continued perpendicular 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 crushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. The slope of tlie fence line where contours must be crossed shall not be steeper than 3:1. 17. Wood, steel or equivalent posts shall be used. Wood posts shall have �ninimum dimensions of 2 inches by 2 inches by 3 feet minimum length, and shall be free of defects such as knots, splits, or gouges. Steel posts shall consist of either size No. 6 reinforcement bar or larger,ASTM A 120 steel pipe with a minilnuin diameter of 1-inch, U,T, L, or C shape steel posts with a minimum weight of 1.35 pounds/feet or other steel posts having equivalent strength and bending resistance to the post sizes listed. The spacing of the support posts shall be a maximum of 6 feet. 18. Fence back-up support, if used, shall consist of steel wire with a maximum mesh spacing of 2 inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 pounds grab tensile strength. The polymeric mesh must be as resistant to ultraviolet radiation as the geotextile 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 posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. 20. Install posts 3 to 4 feet apart in critical retention areas and 6 feet apart in standard applications. - Mainfenance Standards l. Any damage shall be repaired immediately. � 2. If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a sediment pond. 3. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. 4. Sediment deposits shall either be removed when the deposit reaches approxiinately one-third the height of the silt fence, or a second silt fence shall be installed. 5. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced. Volume 11— Construction Stormwater Pollution Prevention 3-56