and the value the dredged material may have as a landfill, wildlife site, or
Peterson (1981) reports a cost range for 64 US
future recreation area.
-3
of
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.24 to .00 m , with a frequent range for hydraulic dredging-3
m . Costs may be reduced through productive or bene-
projects of
ficial use of the dredged material
1981).
Two of the most effective means of controlling internal loading are sed-
iment removal and phosphorus inactivation.
Cooke et al.
have
the cost-effectiveness of these methods, and preliminary evidence suggests
that they may be similar when amortized over the effective life of the
treatment.
Limitations and Concerns
Sediment removal has high potential for both short- and long-term nega-
tive impacts, both at the dredging site and the containment area. Most
these problems are of short duration and can have minimal negative impacts
following project completion when containment area design has been proper.
Sediments contaminated with toxic materials involve special precautions.
Several possible deleterious actions can occur at the dredging site.
include creation of plumes of turbid water, liberation of nutrients
(Churchill, Brashier, and Limmer
destruction of benthic organisms
and Bryneldson
and the release of toxic substances (Murakami
and Takeishi 1977).
At the disposal site, whether in-reservoir or upland,
some of these same problems could occur.
In addition, in-reservoir disposal
may result in burial of organisms and the creation of new and less desirable
substrates.
Upland disposal can create nuisance conditions 'for nearby resi-
dents, contaminate ground water, and discharge toxics in the drainage water.
Detailed descriptions of these problems are found in Chen et al. (1978);
Gambrell, Kincaid, and Patrick (1978); Saucier et al. (1978); and Peterson
(1981).
In general, these reports indicate that sediment removal and disposal
seldom generate significant negative impacts in the short term, except where
toxics such as mercury, cadmium, and chlorinated hydrocarbons are involved.
Little is known about long-term impacts.
A reader contemplating a sediment
removal project is urged to consult these reports, especially Gambrell,
Kincaid, and Patrick (1978) and Francingues et al. (1985).
A brief review of
tential environmental problems and some steps to prevent them follows.
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