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Chapter 4 - Best Management Practices for Erosion and Sediment Control <br />r <br />7. When extra strength filter fabric and closer post spacing are used, the wire mesh <br />support fence may be eliminated. In such a case, the filter fabric is stapled or <br />"■ wired directly to the posts with all other provisions of item No. 6 applying. <br />8. When attaching two silt, fenIces together, place the end post of the second fence <br />inside the end post of the first fence. Rotate both posts at least 180 degrees on a <br />clockwise directlori to create a tight seat with the filter fabric. Drive both posts_ into <br />+r. <br />the ground and bury the flap. (See Plate 4.06g) <br />9, The french shall be.backflled and the soil compacted over the filter fabric. <br />10. The most effective application consists of'a double row of silt fences spaced a <br />minimum of three feet apart. ,The. three foot:sepaination is so that if the first row <br />collapses it will not fall on the second row.- Wire 'or. synthetic mesh is may be used <br />to reinforce the first row. (See Plate 4.06c) <br />11. When used to,contrel sediments from a steep slope, silt ferices should. be placed <br />away from the toe of the slope for increased holding capacity. '(See Plate 4.06f) <br />12. Silt fences shall be removed when they have served their useful purpose, but not <br />before the upslope area has been permanently stabilized. <br />Channel Flow Applications <br />1. If a filter barrier is to be constructed across a ditch line or swale; the barrier shall of <br />sufficient .length such that the bottom of the end sections of fence are higher in <br />elevation than the top of the center section to eliminate end flow.: The pian <br />configuration shall resemble an arc or horseshoe with the ends oriented upslope. <br />(See Plate 4.06b). <br />2. Use FDOT Standard Index 102, Chart 1(Plate 4.06a) as a guide for spacing. <br />41 3. The remaining steps for installing a filter barrier for sheet flow applications apply <br />here. <br />Maintenance <br />1. Silt fences and filter barriers shall be inspected immediately after each rainfall and <br />at least daily during prolonged rainfall. Any required repairs shall be made <br />immediately. <br />2. Should the fabric on a silt fence or filter barrier decompose or become ineffective <br />before the end of the expected usable life and the barrier still be necessary, the <br />fabric shall be replaced promptly. <br />3. Sediment deposits should be removed after each storm event. They must be <br />removed when deposits reach approximately. one-half the height of the barrier. <br />4-27 <br />