Contaminated Marine Sediments Assessment and Remediation (1989) / Chapter Skim
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Dredging and Disposal of Contaminated Marine Sediment for the U.S. Navy Carrier Battlegroup Homeport Project, Everett, Washington
Dredging and Disposal of Contaminated Marine Sediment for the U.S. Navy Carrier Battlegroup Homeport Project, Everett, Washington
Pages 462-482
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From page 462... ...
ABSTRACT In April 1984 the U.S. Navy selected the East Waterway of Port Gardner Bay in Puget Sound as the homeport site for a carrier batt~egroup.
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From page 463... ...
, · CAD site benthic analysis, sediment sampling and analysis, characterization of East Waterway sediments, water column chemistry, physical model of East Waterway, confined aquatic disposal (CAD) feasibility analysis, Port Gardner bathymetric survey,Port Gardner current measurements leachate/sediment settlement tests dump modeling, navigational plans for accurate sediment placement, preconstruction/construction/post-cons true tion CAD site monitoring plan, · Smith Island Upland-Dredge Disposal Feasibility Study & Evaluation, re-characterization of P-lll and P-905 sediment (clean/contaminated)
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From page 464... ...
Contaminated material will be dredged and disposed of using clamshell, tug, and bottom dump scow to ensure minimum induced turbidity and maximum compaction of contaminant mass on the bottom. Hydraulically dredged, native uncontaminated material will be used as capping material, the release rate and density of which will be controlled to prevent displacement of the deposited contaminated sediments through use of a floating pipeline with submerged diffuser.
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From page 465... ...
465 —20 ~ PROJECT | BOUNDARY—j i V ~ ~ _ ant ~ {: ~ \ ~ BOUNDARIES OF CONTAMINATED / ~ ~ /// l \ \ \ To AND UP / ~ ~ ~ 1/ \ \ \\ DREDGE DEPOSITS \ An\ \~PPROXIMATELY~=RES~ ~ ~1/ \\ \ \ ~ / / \\ \ ,'~-' -_ / ~r 1ST YEAR CONSTI `~ \ \ , / / _ ~ by; `} BOUNDARIES OF CONTAMINATED \ X / / ~ ~ \ / ~ [A AND UN~AMINAlED \____ - W~ / DREDGE Do icy/ -EGG ~~//? act/ l SCOTT PAPER //// OUTFALL SCALE IN fEET 0 800 1, 600 FIGURE 1 Revised application for deep confined aquatic disposal.
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From page 466... ...
Uncontaminated Material CaD T4.5 ,@ -430.0+ hi, FIGURE 2 CAD site final consolidated section. I, SEDIMENT ASSESSMENT AND EVALUATION Contaminated Sediment Section Distorted Not to Scale The contaminated sediment consists of the upper layer of sediment in most areas of the harbor ranging from O to 7 ft in thickness.
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From page 467... ...
it. ,~\ MAY SCALE IN YARDS o 1.000 2.000 D - doing Area ^cA-~c-~ Open Water Sites Nearshore Sites ~f~ Upland Sites PORT GARDNER PSD DEEP LTA S E ~ CAD SI" APPUCAT10— FOR DEEP CAD SITE POW GARDNER DISPOSAL SITE ; _ _~5~" Her an_ ~ U;i~1:IL '=~ 0~- .
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From page 468... ...
Chemically Related Dredge Disposal Considerations CAD Standard Elutriate tests were conducted by the COE on the previously noted composite sample of sediments collected from the East Waterway (DSEIS)
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From page 469... ...
. Based on these tests, potential water quality impacts during openwater placement of contaminated sediments (CAD site)
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From page 471... ...
Studies conducted with East Waterway sediments indicate that under these conditions the.concentration of dissolved Cd would substantially exceed EPA water quality criteria. Leachate Testing The potential for generation of leachate from an upland disposal site was studied using experimental laboratory testing procedures for sediments collected from the East Waterway.
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From page 472... ...
If only the contaminated sediments were placed there, the clean sediments would be taken to the Port Gardner aquatic disposal site. A third disposal method involves placement of the contaminated sediments on an upland site on Smith Island.
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From page 473... ...
DREDGING AND DISPOSAL DESIGN Performance Goals Selection of dredging equipment for the contaminated Everett Harbor sediments was based on the following performance goals: 1. Water entrainment during the dredging operation must be .
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From page 474... ...
474 , o · 'Fit o 1 ~ .
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From page 475... ...
Mound construction will be accomplished by clamshell dredging and bottom dump of the clean surficial sediments to the disposal site. During the second phase, contaminated materials will be dredged by clamshell dredge, with haul and dumping by split hull barges of 3,000-yd3 capacity or larger.
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From page 476... ...
This has become an important factor in the regulatory agency considerations to approve the disposal permit because it satisfied the opportunity to check the dredge and disposal design before release of the contaminated sediments at the disposal site. Contaminated Material Placement Clamshell dredging for the contaminated sediment is considered the most compatible dredging method for the CAD disposal alternative.
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From page 477... ...
The total impacted area, where 3 cm or more of dredged material will be deposited, is approximately 380 acres. ENVIRONMENTAL MONITORING The dredging and disposal monitoring plan, phase I document outlines a detailed plan for meeting the conditions outlined in the State Water Quality Certification, and COE Section 10/404 permit of September 24, 1987.
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From page 478... ...
· Sediment cores: sediment box cores at 37 stations will be taken during baseline, with the upper 2 cm of each analyzed for physical properties and 79 PSDDA (Puget Sound Dredge Disposal Analysis) "Chemicals of Concern," all run using Puget Sound Estuary Program (PSEP)
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From page 479... ...
: three-step procedure using current drogues and acoustical transponders for plume tracing, acoustical transponders and transmissometers for plume characterization and state water quality standards monitoring. Water column effects (dredge site)
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From page 480... ...
Even with this background to draw upon, regional environmental concern for Puget Sound necessitated the expenditure of substantial time and money, far beyond previous experience. Currently, for this project, predisposal This paper has presented a summary of the sediment evaluation procedures, disposal alternative assessments, design considerations, and monitoring requirements associated with the dredging and disposal required for construction of the Navy's Carrier Battlegroup Homeport Project in Everett, Washington.
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From page 481... ...
TABLE 3 Summary of Dredging Costsa Item Contaminatedb TotalC Sediment evaluation Disposal alternative evaluation Environmental Monitoring $ 1.26 2.21 8.27 Total nonconstruction costs 11.74 Total dredging and disposal design costs Total Construction Costs 0.35 0.62 2.32 3.29 0.21 4.00-7.00 NOTES aNonconstru~tion costs, expressed as dollars/yd3.
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From page 482... ...
It is generally not in the national interest to allow uncertainty with regard to environmental issues to burden a project having significant social or economic benefits. The responsibility of resolving research questions related to issues of environmental impacts should be jointly shared by the research community and project components.
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