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Chapter 4: - Best Mana ement- Practices .forErasion and Sediment Control <br /> r <br /> ( nstallatiorr <br /> 1 . In the calm water of lakes or ponds (Type 1 installation) it is usually sufficient to <br /> merely set the curtain end stakes or anchor points (using anchor buoys if bottom <br /> anchors are employed) , then tow the curtain in the furled condition out and attach it <br /> to these stakes or anchor points . Following this , any additional stakes or <br /> buoyed <br /> be set and <br /> anchors required to maintain the desired location. of the curtain may. <br /> rtain . Only then , the furling lines should be <br /> these anchor points made fast to the cu <br /> +� cut to let the curtain skirt drop . <br /> 2 .. In rivers or in other moving water (Type 11 and Type III installations) it is important to <br /> .. <br /> set all the curtain an power to aetainfe uthe curtain undest be taken to r theure texpected hat anchorcurrent <br /> are of sufficient holding p <br /> rled curtain into thewater: Anchor buoys should be <br /> conditions , before putting the fu <br /> employed on all anchors to prevent the current from submerging the flotation at the <br /> anchor points . If the moving water into which the curtain is being installed is tidal <br /> and will subject the curtain to currents in both directions as the tide changes , it is <br /> r important to provide anchors on both sides of the curtain for two reasons: <br /> a) Curtain movement will be minimized during tidal current reversals . <br /> b) The curtain will - not overrun the anchors pull there out when the tide <br /> reverses . <br /> r When the anchors are secure , the furled curtain should be secured to the upstream <br /> anchorpoint and then sequentially-attached to each next downstream anchor point <br /> r. until the entire curtain is in position. At this point, and before unfurling , the "lay" of <br /> the curtain should. be assessed ande any. necessary adjustments made to the <br /> anchors. Finallywhen the location is ascertained to be as desired, the furling lines <br /> • should be cut to allow the skirt to drop . <br /> 3 , Alwa s attach' anchor lines to -the flotation device- not to -the battom._of_the curtain . . <br /> The anchogng line attached to the floatation device on the downstream side. will <br /> provide support for the curtain . Attaching the anchors to the bottom of the curtain <br /> could cause premature failure of the . curtain due to the stresses imparted on the <br /> .• middle section of the curtain . <br /> 4. There is an exception to the rule that turbidity curtains should not be installed across <br /> channel flows; it occurs when there is a danger of creating a silt buildup in the <br /> middle of a watercourse, thereby blocking access or, creating a sand bar. Curtains <br /> have been used effectively in large areas of moving water by forming a very <br /> +� long-sided , sharp "V" to deflectclean water around a work site , confine a large part <br /> of the silt-laden water to the work area inside the "V" and direct much of the silt <br /> toward the shoreline . Care must be taken , however, not to install the curtain <br /> perpendicular to the water current. <br /> 5 . See Plate 4.45c for typical installation layouts. <br /> 4-121 <br />