confined disposal facilities and in situ capping
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Confined Disposal Facilities and In Situ Capping. Site characterization / selection Engineering design Operational considerations Contaminant pathways and controls Long-term management Monitoring http://www.youtube.com/watch?v=Lbh9c0noR4s. - PowerPoint PPT PresentationTRANSCRIPT
Confined Disposal Facilities and In Situ
Capping Site characterization / selection Engineering design Operational considerations Contaminant pathways and controls Long-term management Monitoring http://www.youtube.com/watch?v=Lbh9c0noR4s
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Potential Contaminant Release Pathways for Dredging and Upland Disposal
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Confined Disposal Alternatives
Engineering Issues Reduce Contaminant Pathways
Disposal pathways Physical disturbance Seepage
Optimize Capacity Safely dispose of the greatest amount
of material in the smallest area
Physical Disturbance Excavation and removal of
contaminated sediments Erosion and Scour at the disposal site Slope Stability
Nature of underlying materials Stability of existing and future slopes
Intended end use of site Consolidation and settling Cap Properties
Seepage Excess pore water in upland sites Consolidation and compaction
induced seepage Groundwater-driven seepage
Other Considerations Dredged disposal volume Area of land desired Habitat mitigation requirements Cost comparisons
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Local Example: Ross Island
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Ross Island Locator Map
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Aerial Photo
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History of the Ross Island Sand & Gravel Site
July 1926 RISG acquires the islands and ownership is established over the area defined by the low water line surrounding the islands
October 1967 RISG issued removal permit following effective date of Oregon’s removal law
1972 RISG proposed to mine entire islands away - denied by Oregon AG
1972 RISG proposed to connect the northern ends of the islands forming a private pond - denied by COE
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RISG History – Cont’d 1979 RISG’s removal permit amended to include
fill 1980 City of Portland issued Conditional Use
Permit specifying details of eventual reclamation 1983 RISG began accepting fill materials from
outside sources 1992 first confined disposal event of Port of
Portland dredged sediments
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Typical Cross Section
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Disposal Methods
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Potential Contaminant Migration Pathways -
Disposal Processes
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Potential Contaminant Migration Pathways - Groundwater Transport (Present and Future)
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Potential Contaminant Migration Pathways -
Physical Disturbance
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Groundwater Movement through Cells
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Potential Groundwater Transport from Containment Cells
Upward groundwater flow Cap design minimizes discharge
via this sort of flow Predicted discharge
concentrations below risk-based criteria.
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Potential Physical Disturbance of Containment Cells
Natural erosion (floods). Human influence (mining). Geotechnical stability.
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Slope Instability
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Potential Physical Disturbance of Cells
Minimal erosion potential due to a control dike.
Mining controls would avoid future impacts.
Slopes are presently receiving fills.
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RISG CDF: Conclusion Final decision not yet made about
CDF and the future of the island as a city park or preserve
Engineering studies strongly suggest the CDF is presently secure and presents an acceptable risk
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GREENFill Areas Considered
YELLOWFill Areas Proposed
REDAreas to be Dredged
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University
Wyckoff/Eagle Harbor
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Wyckoff/Eagle Harbor Bainbridge Island, in Central Puget
Sound 3,780-acre site Land use in the area is predominantly
residential, with some commercial and industrial uses
The harbor supports several fish resources, a wide variety of resident and migratory birds, and other wildlife
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Eagle Harbor
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Wyckoff/Eagle Harbor Sources of Contamination:
Inactive 40-acre wood treating facility owned by Wyckoff
Adjacent 500-acre Eagle Harbor Other upland sources of
contamination (Shipyard)
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University
Site History Shipyard operated from 1903 to 1959
on the northwest shore of Eagle Harbor, resulting in releases of metals and organic contaminants.
1905 to 1988, wood treating operations were conducted on the southeast shore involving pressure treatment with creosote and pentachlorophenol
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University
Discovery During the 1970s, efforts were made to address oil
seepage on beaches adjacent to the Wyckoff
1984: NOAA investigations of the Harbor revealed that sediment, fish, and shellfish from Eagle Harbor contained elevated levels of PAHs
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The Response to Discovery EPA required Wyckoff to conduct
environmental investigation activities under RCRA
Washington State required immediate action to control stormwater runoff and seepage of contaminants
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Response, Cont’d September 1985: Proposed to the
Superfund NPL 1985:Washington State Hazardous
Waste Cleanup Program, (Ecology): Preliminary Investigation of sediment contamination in Eagle Harbor
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Response, Cont’d 1985: NOAA completed a study relating
the presence of PAHs in sediment to the high rate of liver lesions in English Sole from Eagle Harbor
March 1987, Wyckoff Company entered into an Administrative Order on Consent with EPA for further investigation of the facility (RI/FS)
04/22/23W. Fish, Portland State
University
Historical Sources Preservative chemicals were stored in
tanks on the property. Contamination of soil and ground water at
wood treatment facility led to seepage into adjacent sediments.
Wastewater discharged into Eagle Harbor for many years; storing treated pilings and timber in the water continued until the late 1940's.
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Contaminants of Concern Shipyard: Levels toxic to marine
life Polyaromatic hydrocarbons (PAHs)
and other organics Heavy metals such as mercury,
copper, lead, and zinc
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Contaminants of Concern Wyckoff facility, soil and
groundwater are contaminated with:
Creosote Accompanying PAHs Pentachlorophenol (PCP; “penta”)
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University
CERCLA Operating Units 1991, EPA defined three operable
units at the Wyckoff/Eagle Harbor site:
Wyckoff (OU1) East Harbor (OU2) West Harbor (OU3) Wyckoff Facility groundwater (OU4,
1994)
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Selected Remedial Actions Dredging, excavating dewatering intertidal
sediment that exceeds levels of 5 mg/kg mercury and/or lower, moderate PAH concentrations
Approximately 1,000 to 7,000 cubic yards Solidification/stabilization, as necessary, to
comply with disposal rules Transporting sediment, which cannot be
treated to meet rules offsite for disposal at a RCRA-permitted (Subtitle C or D) landfill
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Remedial Actions (cont’d) Treating dewatering wastewater onsite using
carbon adsorption before discharge into the harbor
Capping the sediment in areas of high concern with a 1- meter thick layer of clean sediment;
Placing a thin layer of clean sediment in subtidal areas of low to moderate concern to enhance natural sediment recovery
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Remedial Actions (cont’d) Long-term environmental monitoring Institutional controls to prevent
exposure to contaminated fish and shellfish.
The estimated cost is up to $16,000,000 Most work done but site still on NPL
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University
Eagle Harbor Cap Areas
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University
East Harbor Capping (OU2)
Sept 1993-March 1994, EPA and the Corps of Engineers covered contaminated sediments in the East Harbor
Cap of clean sediment at water depths of 17 m and 13 m, respectively.
Sediment was dredged from the Snohomish River as part of an annual project for ship navigation
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Capping Methods
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University
Capping Methods Split Hull: Fast but uneven.
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University
Capping Methods Hydraulic washoff:
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University
West Harbor CDF (OU3)
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Final sediment cleanup actions Monitoring the success of natural
recovery in intertidal areas Monitoring contaminated areas where
active remediation cannot be implemented.