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Title: Aquatic disposal field investigations, Duwamish Waterway disposal site, Puget Sound, Washington : Appendix E: Release and distribution of polychlorinated biphenyls induced by open-water dredge disposal activities
Authors: Pavlou, Spyros P.
Dexter, Robert N.
Hom, Wilson
Hafferty, Andrew J.
Krogslund, Katherine A.
Keywords: Aquatic ecology
Puget Sound (Wash.)
Dredging spoil
Dredged material
Polychlorinated biphenyls
Dredged Material Research Program (U.S.)
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (Dredged Material Research Program (U.S.)) ; no. Technical Report D-77-24; Appendix E
Abstract: The potential for adverse impacts associated with open-water disposal of contaminated dredged material is well recognized. However, the physical and chemical behavior of toxic trace constituents in these sediments during disposal operations is poorly understood, thus making regulatory criteria development an extremely difficult process. The objective of the study reported herein was to investigate the release and translocation of polychlorinated biphenyls (PCB) associated with the disposal of contaminated sediments from the Duwamish River in Elliott Bay, Puget Sound, Washington. Based on a detailed analysis of the data obtained during the field program, the most significant findings of this study are outlined below: a.) The material dredged from the Duwamish River contained PCB's as high as 7 mg/kg, a level substantially higher than anticipated for this area of the river. It is unknown whether these high levels represent historic loading which has gone undetected or is recent input. b.) The primary release of PCB's in the water column during disposal was a highly transient event associated with the temporary increase in suspended particulate matter introduced by the dumping operation. PCB concentrations in the water column increased during the dumping events from about 3 ng/l to as high as 3 μg/l. These extreme values were observed only for a few minutes after dumping. c.) A less dramatic increase in PCB levels, to about 10 ng/1, was observed one week after the cessation of dumping at the study site. Within one month, water column PCB levels returned to predisposal concentrations. d.) Long-term elevations of PCB concentrations due to dumping were localized within the sediments of the disposal zone. The values for the surface sediments increased from approximately 0.5 mg/kg to about 3 mg/kg. No dispersal or mobilization of the PCB was observed during the monitoring period. e.) A continuous slumping and spreading of the deposited material was indicated by tracing the changes of the PCB distribution over time. The increasing concentrations in the surface sediments over time and the apparent burial by the highly contaminated materials of the periphery of the disposal zone provided evidence of this occurrence. It is anticipated that the results of this study, coupled with the physical and biological investigations conducted in the area over the same monitoring period, will provide a basis for a realistic evaluation of the environmental impacts of open-water dredged material disposal operations. These will assist in establishing environmentally sound management strategies for future dredged material discharge activities.
Description: Technical Report
Gov't Doc #: Technical Report D-77-24; Appendix E
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Technical Report

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