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1 <br /> Table 4.10 <br /> Geotextile Standards <br /> Polymeric Mesh AOS 0.60 mm maximum for slit film wovens(#30 sieve). 0.30 <br /> (ASTM D4751) mm maximum for all other geotextile types(#50 sieve). <br /> 0.15 mm minimum for all fabric types(#100 sieve). <br /> ' Water Permittivity 0.02 sec'minimum <br /> (ASTM D4491) <br /> Grab Tensile Strength 180 lbs.Minimum for extra strength fabric. <br /> (ASTM D4632) 100 lbs minimum for standard strength fabric. <br /> Grab Tensile Strength 30%maximum <br /> ' (ASTM D4632) <br /> Ultraviolet Resistance 70%minimum <br /> (ASTM D4355) <br /> • Standard strength fabrics shall be supported with wire mesh, chicken <br /> wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the <br /> ' strength of the fabric. Silt fence materials are available that have <br /> synthetic mesh backing attached. <br /> • Filter fabric material shall contain ultraviolet ray inhibitors and <br /> ' stabilizers to provide a minimum of six months of expected usable <br /> construction life at a temperature range of 0°F.to 120°F. <br /> • 100 percent biodegradable silt fence is available that is strong, long <br /> ' lasting,and can be left in place after the project is completed,if <br /> permitt el regulations. <br /> • Standarded Notesby forcal construction plans and specifications follow. Refer <br /> to Figure 4.19 for standard silt fence details. <br /> The contractor shall install and maintain temporary silt fences at the <br /> ' locations shown in the Plans. The silt fences shall be constructed in <br /> the areas of clearing,grading, or drainage prior to starting those <br /> activities. A silt fence shall not be considered temporary if the silt <br /> fence must function beyond the life of the contract. The silt fence <br /> shall prevent soil carried by runoff water from going beneath,through, <br /> or over the top of the silt fence,but shall allow the water to pass <br /> through the fence. <br /> The minimum height of the top of silt fence shall be 2 feet and the <br /> maximum height shall be 2Y2 feet above the original ground surface. <br /> The geotextile shall be sewn together at the point of manufacture, or at <br /> ' an approved location as determined by the Engineer,to form geotextile <br /> lengths as required. All sewn seams shall be located at a support post. <br /> Alternatively,two sections of silt fence can be overlapped,provided <br /> the Contractor can demonstrate,to the satisfaction of the Engineer,that <br /> the overlap is long enough and that the adjacent fence sections are <br /> close enough together to prevent silt laden water from escaping <br /> ' through the fence at the overlap. <br /> February 2005 Volume II—Construction Stormwater Pollution Prevention 4-95 <br />