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surface (i . e . , deposition layer plus ponding) of less than 2 .6 in./hr. These rates are slow enough to allow close continual monitoring of the entire dike perimeter. However, ponding depth should not be permitted to increase beyond a maximum of 5 ft (5 . 8 ft at the weir) . Dike stability should be monitored continuously during periods when ponding depth is maintained above the 2-ft minimum . Optimal operating efficiency requires that flow through the containment basin approachs plug flow to the greatest degree possible. Uneven flow distribution — evidenced by irregular sediment deposition, channelization , and short-circuiting — increases flow velocities, reduces retention time, and promotes sediment resuspension . If inspection reveals an irregular deposition pattern, the inlet pipe should be repositioned to produce a more uniform depositional surface. Last, the incoming slurry should be periodically monitored at the containment basin inlet to confirm or refine dredge output specifications, including volumetric output and slurry solids content. These parameters, in combination with the actual duration of dredging, can be used as an independent measure of deposition volume to determine remaining site capacity. Additionally, the computed deposition volume can be used with pre- and post-dredging bathymetric surveys of the channel and , following placement and dewatering of the deposition layer, topographic surveys within the containment basin to refine the bulking factor employed to translate in situ dredging volume to required storage volume. Also, within the same monitoring program, the quality of dredged sediment should be established by laboratory analysis of grain size distributions, settling velocities, specific gravity, and Atterberg limits . 3.3 Weir Operation Weir operation — that is, controlling the ponding depth and flow rate over the weir by adjusting the weir crest elevation -- is the procedure most critical to maintaining effluent quality during dredging and decanting operations . Operational requirements extend to the period during and immediately after containment basin construction . Initially, the weir crest elevation should be set as high as necessary to prevent unwanted release of stormwater and groundwater seepage. Before the site ' s initial use, the site operator will periodically release ponded stormwater and groundwater seepage during regularly scheduled inspections. 30