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Last modified
1/25/2010 6:46:32 PM
Creation date
10/5/2006 12:43:57 AM
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Floodplain Documents
County
Statewide
Basin
Statewide
Title
Engineering and Design Design and Construction of Levees
Date
4/16/1979
Prepared By
US Army Corps of Engineers
Floodplain - Doc Type
Educational/Technical/Reference Information
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<br />e <br /> <br />EM 1110-2-1913 <br />31 Mar 78 <br /> <br />d. Traverse. A traverse is an unexcavated zone left in place at <br />intervals across the borrow area (figure 4-1). Traverses provide road- <br />w~s across the borrow area, provide foundations for transmission towers <br />and utility lines, prevent less than bank-full flows from coursing un- <br />checked through the borrow area, and encourage material deposition in <br />the borrow area during high water. Experience has shown that when <br />traverses are overtopped or breached, severe scour damage can result <br />unless proper measures are taken in their design. Traverse heights <br />should be kept as low as possible above the bottom of the pit when they <br />will be used primarily as haul roads. In all cases, flat downstream <br />slopes (on the order of IV and 6H to lOH) should be specified to mini- <br />mize scour from overtopping. If the traverse carries a utility line or <br />a public road, even flatter slopes and possibly stone protection should <br />be considered. <br /> <br />. <br /> <br />. <br /> <br />e. Drainage. Riverside borrow areas should be so located and ex- <br />cavated that they will fill slowly on a rising river and drain fully on <br />a falling river. This will minimize scour in the pit when overbank <br />river stages occur, promote the growth of vegetation, and encourage <br />silting where reclamation is possible. The bottom of riverside pits <br />should be sloped to drain aw~ from the levee. Culvert pipes should be <br />provided through traverses, and foreshore areas should be ditched <br />through to the river as needed for proper drainage. Landside pits <br />should be sloped to drain aw~ from or parallel to the levee with <br />ditches provided as necessary to outlet points. Gravity outlets or pump <br />stations should be located so as to minimize lengths of flow paths with- <br />in the pit area. <br /> <br />e <br /> <br />f. Flow Conditions. To avoid damage from confined or restricted <br />flow through the riverside borrow areas, obstructions or impediments to <br />smooth and uniform flow should be removed if possible, or else protec- <br />tive measures must be taken. Riverside borrow areas should be made <br />as uniform in width and grade as possible, avoiding abrupt changes. <br />Removal of obstructions that could cause concentrated flow includes <br />degradation of old levee remnants and of narrow high ground ridges <br />beyond the borrow area, as well as removal of timber from traverses and <br />from foreshore areas immediately adjacent to the borrow area. Obstruc- <br />tions to flow that cannot be removed include transmission towers, bridge <br />piers, and other permanent structures near the levee. In such areas, <br />stone protection should be provided for the levee or borrow area slopes <br />if scour damage is considered probable. <br /> <br />. <br /> <br />~ <br /> <br />g. Environmental Aspects. The treatment of borrow areas after <br />excavation to satisfy aesthetic and environmental considerations has in <br />the last few years become standard operating practice. The extent of <br /> <br />4-4 <br /> <br />e <br /> <br />~ <br />
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