10b. Presentation - Clean-up Design for Middle Third of Lower Duwamish Wate

Item No. 10b  supp
Meeting Date: June 8, 2021
Clean-Up Design for the Middle Third of the
Lower Duwamish Waterway

Joanna Florer
Kathy Bahnick
Sandy Kilroy

Lower Duwamish Waterway (LDW)
Located in South Seattle through Seattle's
industrial core and South Seattle residential
neighborhoods of Georgetown and South Park
Cleanup of the river helps improve
environmental justice communities



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LDW Cleanup Timeline



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Lower Duwamish Waterway Cleanup Goals
Reduce risks to:
1. People who eat resident fish and shellfish
2. People coming into contact with contaminated sediments
3. Bottom dwelling organisms: worms, crabs and clams
4. Fish, birds, and mammals (including salmon and orcas)

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Cleanup Accomplishments
Five "early actions" completed:
Reduced average surface sediment
Lower
levels of polychlorinated biphenyl
(PCB) contamination by 50%
Targeted areas with the highest
PCB contamination in the sediment         Middle
Cleaned up 29 acres of sediment
Design of the Upper Third 2/3
complete                                     Upper
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5th Amendment to the
Administrative Order on Consent (AOC)
Cleanup Design for the middle third
of the LDW - 1.5 miles
Continue monitoring water and
fish/shellfish tissue concentrations
Continue to fund the seafood
consumption advisory efforts
Port's share of cost around $4-5M
from the annual ERL authorization
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Timeline of Current Activities
2019     2020     2021     2022     2023     2024     2025     2026     2027

Cleanup Design of the Upper Third (AOC4)

Cleanup Design of the Middle Third and
Ongoing Monitoring (AOC5)
Seafood Consumption Advisory (AOC1, AOC3, AOC4, and AOC5)

Cleanup Construction

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Elements of the Cleanup Design
Sediment sampling to define the extent of cleanup needed
Determining the appropriate cleanup method
Engineer design drawings and specifications



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Another Notable Sediment Clean-up Milestone
EPA's proposed clean-up plan for the
East Waterway Superfund Site will
be published this summer
Adjacent and downstream of the
LDW and is a separate cleanup
Will also remove a considerable
quantity of PCBs from the
environment, to the benefit of
people, salmon, and orcas
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