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Terminal 108 Remediation

Terminal Overview

Port of Seattle-owned Terminal 108 is located at 4525 Diagonal Avenue S in Seattle on the Lower Duwamish Waterway (LDW) which bounds the property to the west. It is bounded to the east by a King County pumping station and E. Marginal Way S, to the south by Diagonal Avenue S, and to the north by the Oregon Street ROW, Terminal 106W, and a large industrial warehouse building. 

Terminal 108 currently consists of two parcels totaling approximately 20 acres. The Western Parcel (Assessor’s Parcel Number [APN] 7666700510) is approximately nine acres in size, and the Eastern Parcel (APN 7666700515) is approximately 11 acres in size.

The Eastern Parcel (along with T-106W) is currently leased to ConGlobal Industries, an international company that operates container and chassis depots. The primary activities on the Conglobal lease properties include container storage, repair, and chassis storage.

The Western Parcel is currently vacant. A Port public access and habitat mitigation area is located along the southern shoreline of the Western Parcel, adjacent to the LDW. The park area is one of approximately 12 habitat mitigation areas along the LDW shoreline, and public access to the site is provided in accordance with the Port’s public access plan.

As an Ecology source control site, Terminal 108 is combined with the north adjacent Port property Terminal 106W, which is approximately nine acres in size with approximately 1,200 linear feet of shoreline.

Source control overview

Lower Duwamish River Public Access at Terminal 108, Seattle, WA Oct. 18, 2018In 2004, the Washington State Department of Ecology (Ecology), lead agency managing activities that identify and address sources of chemicals contributing to on-going contamination of the LDW, presented a Source Control Strategy designed to guide and regulate comprehensive efforts for reducing sediment recontamination in the LDW, while coordinating with the sediment cleanups addressed in the LDW Remedial Investigation and Feasibility Study.

The strategy and associated Source Control Action Plans (SCAPs) for 24 individual drainage basins around the LDW provide the framework and process for identifying source control issues and implementing practical control for the contaminant of sources.

Source tracing and control efforts include:

  • Mapping of storm drain systems and chemical analyses of samples collected therein
  • Management of discharges from storm drains and CSOs
  • Inspection of local businesses that discharge or otherwise contribute to storm drains, CSOs, or directly to the LDW, and implementation of best management practices
  • Upland cleanups, including remediating contaminated soils, groundwater, and storm drain solids

Ecology chairs the Source Control Work Group (SCWG) consisting of the primary public agencies responsible for source control for the LDW, including:

  • Ecology
  • City of Seattle
  • King County
  • Port of Seattle
  • City of Tukwila
  • WDOT
  • EPA

The success of source control depends on the cooperation of all members of the SCWG and the active participation of businesses that make changes to accomplish source control goals. This adaptive strategy for prioritizing source control work will continue throughout the selection, design, and implementation of the long-term remedy for the LDW.

Current source control activities

The most recent Source Control activities on the terminal required the Port to prepare an EPA Preliminary Assessment and Site Investigation (PA-SI, 2019) under an EPA Settlement Agreement.

The EPA PA-SI completed several objectives:

  • Develop a comprehensive site history
  • Evaluate historical site activities that may have resulted in releases at or from the site
  • Evaluate all available environmental data and compare that data to the relevant screening level
  • Identify data gaps
  • Recommend additional sampling needs to fill those data gaps.

The EPA determined that the Port’s PA-SI report fulfilled the requirements of the order and provided their final approval in January 2019. The Port currently is waiting to hear from the EPA as to the next appropriate steps for site assessment and possibly clean up.


Public involvement

The Port's work on T-108 Source Control has been ongoing since December of 2004. A current timeline of activities includes:



Dec. 2004 Ecology publishes “Duwamish/Diagonal Way Source Control Action Plan (SCAP)”
Jan. 2009 Port publishes “Terminal 108 Environmental Conditions Report”
Oct. 2009 Port publishes “Terminal 108- Western Parcel Source Control Strategy Plan”
2011 Port publishes “Terminal 108- Eastern Parcel Source Control Strategy Plan”
2001 – 2012 Port introduces “Terminal 108 SC Implementation Plan”
2012 – 2014 Implementation of the “Terminal 108 Source Control Implementation Plan”
2014 Port publishes “Terminal 108W, 108E, and 106W Source Control Data Evaluation Report”
2015 Port implementing Terminal 108 West Bank Pilot Stabilization Project
2019 Port completes and EPA Preliminary Assessment of the T-108 west and east parcels


The site is currently undergoing site assessment by the EPA, with participation and review by Ecology. In January 2009, the Port published a comprehensive assessment of the site’s environmental history and potential pathways in the Terminal 108 Environmental Conditions Report.

  • Following an assessment of baseline environmental conditions, the Port prepared the Terminal 108 - Western Parcel Source Control Strategy Plan, dated October 30, 2009, which identifies real or potential recontamination pathways and matched these with the appropriate source control measures for reducing or eliminating contamination pathways to the waterway sediment.
  • A Source Control Strategy Plan for Terminal 108 East and Terminal 106 West was published on August 29, 2011.
  • A sampling and analysis plan for this Source Control Strategy Plan was completed and published on June 8, 2012.
  • Data was collected and analyzed and has been published in the Source Control Data Evaluation Report dated June 2014.
  • In 2019, the Port published an EPA Preliminary Assessment and Site Investigation.
  • To access these and other published environmental 

Contact us

Roy Kuroiwa, Port of Seattle Project Manager

Lily Ninburg, Port of Seattle Seaport Property Manager

Richard Thomas, Department of Ecology Site Manager

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