confined disposal facilities and in situ capping

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

04/22/23W. Fish, Portland State

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.