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be a maximum of 6-feet. Posts shall consist of either: <br />. Wood with dimensions of 2-inches by 2-inches wide min. and a 3-feet <br />min. length. Wood posts shall be free of defects such as knots, splits, or <br />gouges. <br />. No. 6 steel rebar or larger. <br />. ASTM A 120 steel pipe with a minimum diameter of 1-inch. <br />. U, T, L, or C shape steel posts with a minimum weight of 1.35 Ibs./ft. <br />. Other steel posts having equivalent strength and bending resistance to <br />the post sizes listed above. <br />11. Locate silt fences on contour as much as possible, except at the ends of the <br />fence, where the fence shall be turned uphill such that the silt fence captures <br />the runoff water and prevents water from flowing around the end of the fence. <br />12. If the fence must cross contours, with the exception of the ends of the fence, <br />place gravel check dams perpendicular to the back of the fence to minimize <br />concentrated flow and erosion. The slope of the fence line where contours <br />must be crossed shall not be steeper than 3H A V. <br />Gravel check dams shall be approximately 1-foot deep at the back of <br />the fence. Gravel check dams shall be continued perpendicular to the <br />fence at the same elevation until the top of the check dam intercepts the <br />ground surface behind the fence. <br />. Gravel check dams shall consist of crushed surfacing base course, <br />gravel backfill for walls, or shoulder ballast. Gravel check dams shall be <br />located every 10 feet along the fence where the fence must cross con- <br />tours. <br />. Refer to Fiqure II-4.2.13 Silt Fence Installation by Slicing Method (p.374) for slicing <br />method details. Silt fence installation using the slicing method specifications: <br />The base of both end posts must be at least 2- to 4-inches above the top of <br />the filter fabric on the middle posts for ditch checks to drain properly. Use a <br />hand level or string level, if necessary, to mark base points before install- <br />ation. <br />2. Install posts 3- to 4-feet apart in critical retention areas and 6- to 7-feet apart <br />in standard applications. <br />3. Install posts 24-inches deep on the downstream side of the silt fence, and as <br />close as possible to the filter fabric, enabling posts to support the filter fabric <br />from upstream water pressure. <br />4. Install posts with the nipples facing away from the filter fabric. <br />2014 Stormwater Management Manual for Westem Washington <br />Volume 11 - Chapter 4 - Page 372 <br />