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SECTION 5.5: EROSION CONTROL <br />EC 8: Berm /Diversion <br />EC 8: BERWDIVERSION <br />Description A temporary berm or ridge made of soil (or coarse aggregate), with or <br />without a diversion channel. <br />Applications <br />Limitations <br />Design <br />Guidelines <br />• Used to intercept and divert runoff to desired location such as towards a <br />sediment trap or a slope drain. <br />• Used to divert runoff from areas where it might damage property, cause <br />erosion, or interfere with the establishment of vegetation. <br />• Used along the top edges of cuts and fills to protect the embankment. <br />• Used as a temporary feature. <br />• Berms to intercept and divert runoff should not be used where the <br />drainage area exceeds 10 acres. <br />Should not be used in areas with slopes steeper than 10 percent. <br />Location <br />• Appropriate location should be determined by considering outlet <br />conditions, topography, land use, soil type, length of slope, and areas <br />where seepage might be a problem. <br />Berm <br />• Berms shall have a minimum height of 18 inches, side slopes of 2:1 or <br />flatter, and a minimum base width of 4.5 feet (see Figure EC 8.1). <br />Diversion channel <br />• The diversion channel shall have a minimum capacity to convey the <br />runoff expected from a 2 -year frequency storm. Diversions to protect <br />homes, schools, industrial buildings, roads, parking lots, and comparable <br />high risk areas, as well as those intended to function in connection with <br />other structures, shall have sufficient capacity to carry peak runoff <br />expected from a storm frequency consistent with the hazard involved. <br />Design channel in accordance with the CDOT Drainage Design Manual. <br />• The minimum freeboard shall be 6 inches. <br />• The geometry may be parabolic, trapezoidal, or V- shaped (see <br />Figure EC 8.1). <br />5-26 <br />