to evaluate the short-term potential of sediments and disposal area effluents
to release hazardous substances into the water column.
Dredge selection
S. A. Peterson's definitive review of sediment removal (in Cooke et al.
1986) provides detailed criteria for the selection of dredge equipment.
Additional data are available in Pierce (1970). Since this selection can be
highly site specific, the reader
to consult these reports.
Containment area design
One of the most common problems with the use of sediment removal is
inadequate design of the containment area.
Detailed summaries of the pro-
cedures for containment area design are found in
Montgomery, and
Poindexter (1978); Montgomery (1978, 1980, 1982, 1984); Averett, Palermo, and
Wade (1988); and US Army Corps of Engineers (1987).
The volume of sediments to be removed and the sediment characteristics,
such as water content, Atterburg limits, organic content, specific gravity,
bulking, grain size, consolidation, and shear strength, must be known.
Montgomery (1978) and Averett, Palermo, and Wade (1988) describe the floccu-
lent settling test, which is used to ensure solids retention.
These data
allow the design of a confined disposal area that will have sufficient volume
and area to accommodate continuous hydraulic dredging, and is large and deep
enough to allow settling to occur so that the effluent meets suspended solids
Reservoir sediments can be very flocculent, with a low specific
requirements.
gravity (Walsh, Bemben, and Carranza
and the water detention
of
the disposal area must be sufficient to allow these materials to settle. If
the suspended solids requirement is not met, the project may have to be tempo-
rarily stopped or the discharge chemically treated to improve suspended solids
In either case, project costs will escalate.
removal.
Therefore, disposal
area design criteria are meant for end-of-project efficiency and not some
average or estimated discharge requirements over the entire project period.
It is important to note that there is a wide range of settling velocities for
sediments so that the use of averages or literature values may produce poorly
designed containment areas.
The design of a containment area is site specific
and should be based. on the laboratory settling test (Averett, Palermo, and
Wade
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