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returns to the main channel starting downstream of the Ash Avenue Bridge, at river station 24158 in the <br />Western Sugar Reclamation site. Because of this split flow return, the total flow in the channel <br />incrementally increases through the site (Table 1). <br />The USACE Manning's roughness coefficients for the overbank areas through the site range from 0.049 <br />to 0.055. These are higher than the recommended values of 0.02 -0.035 for short grass and 0.02 -0.04 for <br />cultivated areas not planted with crops, leading to conservative WSEL values in the overbank (USDOT, <br />2001, pg. 2.22). <br />In addition to the USACE model, there is a Conditional Letter of Map Revision (CLOMR) issued by FEMA <br />on February 14, 2006 for the site immediately downstream of the Western Sugar Reclamation site. The <br />CLOMR includes possible changes to the water surface elevation due to the construction of the Durham <br />Pit on the property immediately downstream of the Western Sugar Reclamation site. It is described in <br />the report prepared by Anderson Consulting, Inc. dated October 4, 2004. The CLOMR models split <br />channel flow through Durham Pit, lowering local water surface elevations. However, there is negligible <br />proposed change in elevation through the Western Sugar site (Table 2), and therefore the USACE <br />existing conditions model was determined to be the correct model for all further analysis. <br />Proposed Conditions <br />The site is proposed to be developed as a sand and gravel pit with a 100 foot setback from the river. <br />Proposed side slopes of the pit are 1.25:1 for the first 30 feet and then 3:1 to the bottom of the pit, with <br />a maximum total depth of approximately 45 feet (Plate 4). The elevation of the 100 foot berm would be <br />the same as the existing ground. Four pits are proposed and are identified as Tracts A -D, with Tract A <br />being the southeast pit, Tract B being the southwest pit, Tract C being the northwest pit and Tract D <br />being the northeast pit. For Tract C, the approximate elevation of the proposed berm is 4630 at the <br />upstream side and 4625 at the downstream side, with a relatively constant slope between the two <br />points. For Tract D the proposed berm elevation is approximately 4624, which is constant along the <br />river front. Under the proposed operations plan, the pit would not be operated under flood conditions, <br />and water would be allowed to flood the pit to the level of the adjacent river. <br />Potential for Overtopping and Erosion <br />The areas of maximum overtopping and erosion potential are shown on Plate 4, and are explained <br />below in detail. <br />4IPage <br />