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2009-323A
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2009-323A
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Last modified
3/17/2016 1:36:04 PM
Creation date
10/1/2015 12:58:28 AM
Metadata
Fields
Template:
Official Documents
Official Document Type
Certificate
Approved Date
12/15/2009
Control Number
2009-323A
Agenda Item Number
8.D.
Entity Name
Florida Inland Navigation District
Subject
Dredged Material Exhibit B
Supplemental fields
SmeadsoftID
7963
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Three corrugated metal half-pipes, each with an 8-ft weir section , will provide the required 24- ft total <br /> crest length . The three halUpipes connected by a common manifold will provide drainage from the <br /> containment basin via a single culvert under the dike. During dredging and dewatering operations, the return <br /> water pipeline will connect to this culvert and transport the clarified supernatant to the Indian River. Pipeline <br /> placement and retrieval is discussed in Section 3 . 1 . <br /> Removable flashboards will allow adjustment ofweir height over a range of 10. 9 ft - from the initial <br /> elevation of ponded water within the basin following construction (estimated as + 1 . 8 ft NGVD) to a <br /> maximum elevation of + 12 .7 ft NGVD . Setting the weirs at the minimum elevation permits the immediate <br /> release of ponded water at the start of dredging operations. The maximum elevation provides a 2 ft mean <br /> ponding depth and 2 ft of freeboard above the maximum deposition surface . The 5 . 5 in. X 5 . 5 in . flashboards <br /> (finished dimension) provide an adjustment increment roughly equivalent to the projected depth of flow (4 .2 <br /> in . ) over the weir crest at the point the weir discharge approximately equals the liquid inflow to the <br /> containment basin , a balance reflected by the design weir loading, Q/$ = 0. 89 ft'/ft-sec . This design provides <br /> adequate adjustment resolution to maximize weir performance and effluent quality throughout the dredging <br /> operation and subsequent release of ponded water. <br /> The final weir design parameter considered is the location ofthe weirs within the containment basin . <br /> First, to reduce the likelihood of flow constriction, sediment resuspension, and dike instability the weir crests <br /> must be offset a minimum of 100 ft from the dike' s inside toe. Second , the weirs must be placed to maximize <br /> their distance from the dredge pipe inlet and to minimize the return distance to the receiving waters. <br /> Providing the maximum inlet weir separation also maximizes the basin ' s effective area and ensures that the <br /> effluent released from the basin meets the weirs ' performance criteria. Hydraulic analysis (Section 2 . 3 . 3 ) <br /> indicates the 800-ft separation distance shown in Figure 2. 1 to be adequate. In addition, locating the weirs <br /> to minimize the return distance from the weirs to the Indian River provides the most efficient effluent <br /> transport from the containment basin . Gravity flow will be used to the greatest extent possible. However, <br /> one or more dredging operations may be required to sufficiently raise the elevation of the basin interior such <br /> that all ponded water will drain by gravity flow. Until that time, auxiliary pumping may be required . <br /> Analysis ofweir performance based on nomograms developed at the Waterways Experiment Station <br /> under the Dredged Material Research Program (Walski and Schroeder, 1978) indicates that the weir design <br /> 15 <br />
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