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Florida Erosion and Sediment Control Inspector's Manual <br /> Anti -seep collars <br /> Anti -seep collars shall be used on the barrel of the principal spillway within the normal <br /> saturation zone of the embankment to increase the seepage length by at least 10 % , if either <br /> r. <br /> of the following two conditions is met: <br /> 1 . The settled height of the embankment exceeds 10 feet (3 m ) . <br /> 2 . The embankment has a low silt-clay content ( Unified Soil Classes SM or GM ) and <br /> the barrel is greater than 10 inches (25 cm ) in diameter. <br /> The anti-seep collars shall be installed within the saturated zone . The maximum spacing <br /> between collars shall be 14 times the projection of the collar above the barrel . Collars shall <br /> not be closer than 2 feet (60 cm ) to a pipe joint. Collars should be placed sufficiently far apart <br /> to allow space for hauling and compacting equipment. Connections between the collars and <br /> the barrel shall be watertight. See Plate 4 . 26e and Appendix 1 . 26Afor design procedure and <br /> details . <br /> Emergency Spillway <br /> The emergency spillway shall consist of an open channel constructed next to the embankment <br /> over undisturbed material or properly compacted fill . The spillway shall have a control section <br /> at least 20 feet (6 m ) in length . The control section is a level portion of the spillway channel at <br /> the highest elevation in the channel . (See Appendix 1 .26A and Plate 4 . 26f) . The primary <br /> spillway and the emergency spillway shall both discharge to stabilized outlets . (See Plate ., <br /> 4 . 26g ) . <br /> Capacity <br /> The emergency spillway shall be designed to carry the peak rate of runoff expected from a <br /> 10-year storm , less any reduction due to the flow through the principal spillway. See Appendix .. <br /> 1 .26A for design details . <br /> Design elevations <br /> The design high water through the emergency spillway shall be at least one foot (30 cm ) below <br /> the top of the embankment. The crest of the emergency spillway channel shall be at least one <br /> foot (30 cm ) above the crest of the principal spillway . <br /> Location <br /> The emergency spillway channel shall be located to avoid fill material . If constructed on fill , the <br /> fill will be properly compacted in lifts . The channel shall be located so as to avoid sharp turns <br /> or bends . The channel shall return the flow of water to a defined channel downstream from the <br /> embankment . <br /> 4-88 <br />