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1 <br /> ' 1. The contractor shall install and maintain temporary silt fences at the locations <br /> shown in the Plans. <br /> 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting <br /> those activities. <br /> 3. The silt fence shall have a 2-feet min. and a 21/2-feet max. height above the <br /> original ground surface. <br /> 4. The filter fabric shall be sewn together at the point of manufacture to form fil- <br /> ter fabric lengths as required. Locate all sewn seams at support posts.Altern- <br /> atively, two sections of silt fence can be overlapped, provided the Contractor <br /> ' can demonstrate, to the satisfaction of the Engineer, that the overlap is long <br /> enough and that the adjacent fence sections are close enough together to <br /> prevent silt laden water from escaping through the fence at the overlap. <br /> ' 5. Attach the filter fabric on the up-slope side of the posts and secure with <br /> staples, wire, or in accordance with the manufacturer's recommendations. <br /> ' Attach the filter fabric to the posts in a manner that reduces the potential for <br /> tearing. <br /> 6. Support the filter fabric with wire or plastic mesh, dependent on the properties <br /> of the geotextile selected for use. If wire or plastic mesh is used,fasten the <br /> mesh securely to the up-slope side of the posts with the filter fabric up-slope <br /> of the mesh. <br /> 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spa- <br /> cing of 2-inches, or a prefabricated polymeric mesh. The strength of the wire <br /> or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile <br /> strength. The polymeric mesh must be as resistant to the same level of ultra- <br /> , violet radiation as the filter fabric it supports. <br /> 8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. <br /> Backfill and tamp soil in place over the buried portion of the filter fabric, so <br /> that no flow can pass beneath the fence and scouring cannot occur. When <br /> wire or polymeric back-up support mesh is used, the wire or polymeric mesh <br /> ' shall extend into the ground 3-inches min. <br /> 9. Drive or place the fence posts into the ground 18-inches min. A 12—inch min. <br /> depth is allowed if topsoil or other soft subgrade soil is not present and 18- <br /> inches cannot be reached. Increase fence post min. depths by 6 inches if the <br /> fence is located on slopes of 3H:1V or steeper and the slope is perpendicular <br /> to the fence. If required post depths cannot be obtained,the posts shall be <br /> adequately secured by bracing or guying to prevent overturning of the fence <br /> due to sediment loading. <br /> 10. Use wood, steel or equivalent posts. The spacing of the support posts shall <br /> 2014 Stormwater Management Manual for Western Washington <br /> Volume II- Chapter 4 -Page 371 <br />