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<br />e <br /> <br />. <br /> <br />.. <br /> <br />e <br /> <br />. <br /> <br />. <br /> <br />e <br /> <br />:EM 1110-2-1913 <br />31 Mar 78 <br /> <br />CRAFTER 6 <br /> <br />SLOPE DESIGN AND SETTLEMENT <br /> <br />Section I. Embankment Stability <br /> <br />6-1. Embankment Geometry. <br /> <br />a. Slopes. Low levees and levees to be built of good material <br />resting on proven foundations may not require extensive stability <br />analysis. For these cases, practical considerations such as type and <br />ease of construction, maintenance, and operation, and slope protection <br />criteria control the selection of levee slopes. When there is concern <br />about the adequacy of available ~bankment materials or foundation con- <br />ditions, embankment design requires detailed analysis. <br /> <br />(1) Type of construction. Fully compacted levees generally enable <br />the use of steeper slopes than those of levees constructed by semi- <br />compacted or hydraulic means. In fact, space limitations in urban areas <br />often dictate minimum levee sections and select material must be ob- <br />tained and compacted properly to obtain a stable section. <br /> <br />(2) Ease of construction. A IV on 2H slope is generally accepted <br />as the steepest slope that will permit machine placement of riprap and <br />also the steepest slopes that will ensure stability of the riprap <br />blanket. <br /> <br />(3) Maintenance. A 2V on 5H slope is the steepest slope that can <br />be conveniently traversed with conventional mowing equipment. <br /> <br />(4) Slope protection. Riverside slopes flatter than those re- <br />quired for stability may have to be specified to provide protection from <br />damage by wave action. <br /> <br />(5) Floodfighting. Some districts specify a somewhat flatter <br />upper lands ide slope than necessary for stability to provide a ready <br />source of additional material should emergency raising of the levee <br />grade become necessary. <br /> <br />b. Crown Elevation. The levee grade is established by the design <br />flood profile computations plus allowances for settlement and freeboard. <br />The purpose of a freeboard allowance is to provide for those factors <br />that cannot be rationally accounted for in design flood profile computa- <br />tions. Freeboard allowances for levees have not been strictly stan- <br />dardized but minimum values most commonly used are 2 ft for agricultural <br /> <br />6-1 <br />