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repositioned as dictated by the deposition pattern , can effectively distribute the coarse sediment over the basin floor. A flow-splitter or a spoon to break the jet' s momentum will also help the single inlet distribute the slurry. Regardless of the inlet design or operation , maintenance of optimal basin performance will require regrading the dewatered sediment to reestablish the initial uniform slope of about 0 . 2% ( Section 2 .2 . 2) from inlet to weir before each successive placement operation . Preliminary analysis of the settling characteristics of the dredged material to be placed in the IR- 14 containment basin (Section 2 . 3 . 3 ) indicates that the available distance between inlet and weirs will afford adequate solids retention. Moving the inlet for more even material distribution must not significantly reduce this separation distance without additional precautions. To ensure continued compliance with water quality standards, these additional precautions may include increasing the ponding depth or installing turbidity screens surrounding the weirs . 2. 3. 2 Weirs The IR- 14 facility will use weirs to control the release of the clarified surface layer of the water ponded within the containment basin . Adjustment of weir height controls ponding depth within the containment basin which in turn controls basin retention time. Weir height and ponding depth are discussed in more detail in the next section . However, several additional aspects of weir design affect the flow of water inside the basin and thereby strongly influence the efficiency of solids retention and the quality of effluent released from the site . These include weir crest width, weir crest length , weir type, and the location of the weir within the containment basin . Each of these design aspects and its effect on basin efficiency is discussed in the following paragraphs . The first two weir design parameters, weir crest width and weir crest length, affect weir performance by determining its withdrawal depth. The withdrawal depth lithe depth at which gravity forces on suspended sediment particles exceed the inertial forces associated with flow over the weir. It therefore represents the depth of the surface layer of ponded water that is drawn over the weir crest and released from the containment basin . Maintaining the withdrawal depth less than the ponding depth reduces the possibility of resuspending sediment which has settled out of the upper water column . Moreover, since the concentration of suspended sediment increases with depth, minimizing the depth of the withdrawal layer 13