3900 BROADWAY BASE FILE 2016-01-01 MF Import

CISY OF EVERETT.STORMWATER MANAGEMENT MANUAL Table 3.10 Geotextile Standards for Silt Fences ' Polymeric Mesh AOS(ASTM 0.60 mm maximum for film woven(#30 sieve). 0.30 mm 04751) maximum for all oMer geolextile types(#50 sieve). 0.15 mm minimum for all Fabric types(#100 sieve). Water Pertnittivity(ASTM D4491) 0.02 sec' minimum Grab Tensile Strength(ASTM 180 Ibs. Minimum for extre strength fabric. D4632) 100 Ibs minimum for standard sVength fabric. Grab Tensile Strength(ASTM 30%maximum D4632) Ultraviolet Resistance(ASTM 70°/a minimum D4355) 6. Standerd strength fabrics shall be supported with wire mesh,chicken wire,2 x 2-inch wire,safety fence,or jute mesh to increase the strength of the(abric. Silt (ence materials are available that have synthetic mesh backing attached. 7. Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable;onstruction life at a temperaturc range of 0°F to 120°F. 6. 100 percent biodegradable silt�aoce is available that is strong, long lasting,and can be left in placc after the project is comp leted,if pemritted by local regulations. 9. The contractor shall install aad maiotain temporary silt Fences at the locations shown in the plans. 1'he silt fences shall be constructed in the azeas of clearing,grading,or draipage prior to slartiug thosc activities. A silt fence shall oot be considered temporary if the silt fence must function beyond the life of the contract. The silt fence shall pmvent soil camed by runoff water from going beneath,through,or over the top of the silt fence,but shall allow the water lo pass through the fence. 10. 'fhe minimum height of the top of silt fence shall bc 2 feet and the maximum height shall be 2.5 feet above the original ground surface. I L The geotcxtile shall be sewn togethcr al the point of manu(achue,or at an approved location as determined by the engineer,to focm geotextilc lengths as requucd. All sewn scams shall bc located at a support post. Altematively,two scctions of silt fcnce can be ovedapped,provided Ihc contractor c90 demonstrate,to the satisFaction of the engineer,that the overlap is long enough and that the adjacent fence seccions arc close enough together to prevent silt ladcn water from escaping ihrough the fence nt the ovednp. 12. The geotextile shall be attached on the up-slope side�f the posts and support system wilh staplcs, w'vc,or in accordancc with lhe manufacture�'s recommendations. The geoteztile shail be attac6ed to the posts in a manner lhat reduces the potcntial for geotcztile rearing at the staples, w'vc,or othcr conncction device. Silt fence back-up support for thc geotexlile in the fartn of a wirc or plastic mcsh is dependcnt on the propetties o(the geotcxtile sclected for use. if wirc or plastic back-up mesh is used,the mesh shall be fastened securely to the up•slope of the posts with the gcotextile being up-slope of the mesh back-up support. 13. The geotextile at the bottom of thc fence shall be buried in a trench to a minimum depth o( 4 inches below the ground surface. The trench shall be backfilled and the soil tamped in pl;ce over thc buried portion of the geotextilc,such that no flow can pass beneath the fence and scouring cannot occur. When wire or polymeric back-up suppon mesh is used,the wire or polymeric mesh shall extend into the trench a minimum of 3 inches. Volume II—Construction Stormwafer Pollution Prevention 3-55