1515 132ND ST SE 2022-01-20 - Laserfiche WebLink

1. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 3. The silt fence shall have a 2-feet min. and a 2'h-feet max. height above the original ground surface. 4. The filter fabric shall be sewn together at the point of manufacture to form fil- ter fabric lengths as required. Locate all sewn seams at support posts. Altern- atively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the filter fabric on the up -slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's recommendations. Attach the filter fabric to the posts in a manner that reduces the potential for tearing. 6. Support the filter fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up -slope side of the posts with the filter fabric up -slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spa- cing of 2-inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultra- violet radiation as the filter fabric it supports. 8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the filter fabric, so that no flow can pass beneath the fence and scouring cannot occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the fence posts into the ground 18-inches min. A 12—inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18- inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1 V 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. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall 2014 Stormwater Management Manual for Western Washington Volume 11 - Chapter 4 - Page 371