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
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
4/27/2015 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
4/27/2015 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.
4/27/2015 Potential Physical Disturbance of Containment Cells Natural erosion (floods). Human influence (mining). Geotechnical stability.
4/27/2015 Potential Physical Disturbance of Cells Minimal erosion potential due to a control dike. Mining controls would avoid future impacts. Slopes are presently receiving fills.
4/27/2015 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
4/27/2015 GREEN Fill Areas Considered YELLOW Fill Areas Proposed RED Areas to be Dredged
4/27/2015W. Fish, Portland State University Wyckoff/Eagle Harbor
4/27/2015 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
4/27/2015 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)
4/27/2015W. Fish, Portland State 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
4/27/2015W. 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
4/27/2015 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
4/27/2015 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
4/27/2015 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)
4/27/2015W. 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.
4/27/2015 Contaminants of Concern Shipyard: Levels toxic to marine life Polyaromatic hydrocarbons (PAHs) and other organics Heavy metals such as mercury, copper, lead, and zinc
4/27/2015 Contaminants of Concern Wyckoff facility, soil and groundwater are contaminated with: Creosote Accompanying PAHs Pentachlorophenol (PCP; “ penta ” )
4/27/2015W. Fish, Portland State 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)
4/27/2015 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
4/27/2015 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
4/27/2015 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
4/27/2015W. Fish, Portland State University Eagle Harbor Cap Areas
4/27/2015W. Fish, Portland State 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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