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1 <br /> The geotextile shall be attached on the up-slope side of the posts and <br /> P P <br /> support system with staples,wire, or in accordance with the <br /> manufacturer's recommendations. The geotextile shall be attached to <br /> the posts in a manner that reduces the potential for geotextile tearing at <br /> the staples,wire, or other connection device. Silt fence back-up <br /> ' support for the geotextile in the form of a wire or plastic mesh is <br /> dependent on the properties of the geotextile selected for use. If wire <br /> or plastic back-up mesh is used, the mesh shall be fastened securely to <br /> the up-slope of the posts with the geotextile being up-slope of the <br /> mesh back-up support. <br /> ' The geotextile at the bottom of the fence shall be buried in a trench to <br /> a minimum depth of 4 inches below the ground surface. The trench <br /> shall be backfiiled and the soil tamped in place over the buried portion <br /> ' of the geotextile, such that no flow can pass beneath the fence and <br /> scouring can not occur. When wire or polymeric back-up support <br /> mesh is used,the wire or polymeric mesh shall extend into the trench a <br /> ' minimum of 3 inches. <br /> The fence posts shall be placed or driven a minimum of 18 inches. A <br /> minimum depth of 12 inches is allowed if topsoil or other soft <br /> ' subgrade soil is not present and a minimum depth of 18 inches cannot <br /> be reached. Fence post depths shall be increased by 6 inches if the <br /> fence is located on slopes of 3:1 or steeper and the slope is <br /> i perpendicular to the fence. If required post depths cannot be obtained, <br /> the posts shall be adequately secured by bracing or guying to prevent <br /> overturning of the fence due to sediment loading. <br /> Silt fences shall be located on contour as much as possible, except at <br /> ' <br /> thethe endssiltfence of thcapture fencees,wheretheruno theff fence <br /> water shalland beprevent turnsed uphwater froill suchm that <br /> flowing around the end of the fence. <br /> ' If the fence must cross contours,with the exception of the ends of the <br /> fence, gravel check dams placed perpendicular to the back of the fence <br /> shall be used to minimize concentrated flow and erosion along the <br /> back of the fence. The gravel check dams shall be approximately 1- <br /> foot deep at the back of the fence. It shall be continued perpendicular <br /> to the fence at the same elevation until the top of the check dam <br /> ' intercepts the ground surface behind the fence. The gravel check dams <br /> shall consist of crushed surfacing base course, gravel backfill for <br /> walls,or shoulder ballast. The gravel check dams shall be located <br /> every 10 feet along the fence where the fence must cross contours. <br /> The slope of the fence line where contours must be crossed shall not <br /> be steeper than 3:1. <br /> ' Wood, steel or equivalent posts shall be used. Wood posts shall have <br /> minimum dimensions of 2 inches by 2 inches by 3 feet minimum <br /> length, and shall be free of defects such as knots, splits, or gouges. <br /> ' 4-96 Volume Il-Construction Stormwater Pollution Prevention February 2005 <br />