Framework for Dredged Material Management
often require major investments in operational control for efficient operation. Natural ion-
exchange media, such as zeolites, may be effective but have not been demonstrated in
this application. Use of man-made wetlands for retention of heavy metals and other
contaminants from effluents could represent a viable option for certain sites and
contaminants (Fennessy and Mitsch 1989). Less likely choices include biological ion
exchange, electrocoagulation, and ultrafiltration. More detailed guidance on metals
treatment processes as applied to CDFs is available (Cullinane et al. 1986; Averett et al.
22.214.171.124 Organics Treatment
The applicability and effectiveness of options for treatment of dissolved organic
contaminants are mostly dependent on the concentration and flow of the liquid stream.
Mechanical biological wastewater treatment processes are typically not considered
because it is doubtful that sufficient organic matter would be available to support
biological growth and because operation of biological systems under the conditions of
fluctuating flows and temperatures would be difficult. Biological processes such as
nitrification, nutrient catabolism, and photosynthesis are important degradation
mechanisms for nutrients, oxygen-demanding materials, and other organics in CDFs. The
principal process for dissolved refractory organic contaminants that has been applied to
dredged material effluent is carbon adsorption, which was applied to a PCB spill on the
Duwamish Waterway in the 1970s (Blazevich et al. 1977). Air and steam stripping could
be used for volatile contaminants, but these are generally not a problem for contaminants
originating in most dredged sediments. Ultraviolet light (UV) and chemical oxidation
processes offer destruction of organic contaminants and are being extensively
investigated in the field for a wide range of contaminants. Created wetlands also offer
potential for retention and degradation of organics. The more effective organic treatment
process options are:
Chemical oxidation using ozone.
More detailed guidance on organics treatment processes as applied to CDFs is available
(Cullinane et al. 1986; Averett et al. 1990; USACE 1983 and USACE in preparation).
5.4.3 Site Controls
Site controls (e.g., surface covers and liners) can be effective control measures
applied at a CDF to prevent migration of contaminants from the dredged material
(Cullinane et al. 1986; Averett et al. 1990). The implementability and effectiveness of