Facility Site ID: 139 Cleanup Site ID: 2876

Status: Sediment Unit Engineering Design Underway

Aerial map of Gas Works Park site
Aerial map of Gas Works Park site

Información en español | 有關清理工作的中文信息 | Impormasyon sa Tagalog

Last Updated July 2023

2023 fact sheet

2023 Response to Comments

From June 20 – July 20, 2023, Ecology invited review of a cleanup action plan and associated documents for the cleanup of remaining contamination at the Gas Works Park site. The plan calls for removing and capping shoreline soil, treating shoreline groundwater, dredging sediment, capping sediment, monitoring, and administrative site use controls.

The plan is part of a legal agreement between Ecology, the City of Seattle (City), and Puget Sound Energy (PSE).

The following documents were available for review:   

Next Steps
Ecology has reviewed and considered the public comments received on the documents, and no edits to the documents are necessary.  Ecology is finalizing the documents.

From 2023 – 2027, engineering design and permitting will continue, including additional investigations and evaluations to refine the cleanup action and enable detailed design work. Construction is planned to begin in 2027.

Site Units And Remaining Contaminated Areas

Gas Works Park site units
Gas Works Park site units
The Gas Works Park site consists of two units, a 21-acre Upland Unit and a 56-acre in-water Sediment Unit.  Multiple previous cleanup actions have addressed contamination in the Upland Unit, except for bank soil and arsenic-contaminated groundwater along the shoreline.

Sediment throughout the Sediment Unit is contaminated.  

Contaminants present are from former upland industrial operations and include polycyclic aromatic hydrocarbons, arsenic, nickel, carbazole and dibenzofuran.  Additional contaminants associated with other sources in Lake Union are also present in sediment.

General Cleanup Process

The Model Toxics Control Act (MTCA) is Washington’s environmental cleanup law. It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups. The MTCA site cleanup process is completed in steps (see graphic below) over a variable timeline.
Click image to enlarge
Click image to enlarge

What Happens Next?

  • June 20 - July 20, 2023:  Public comment period
  • June 28, 2023:  Online public meeting (Download presentation PDF)
  • Fall 2023: Public comments addressed, and cleanup action plan finalized
  • 2023 to 2027: Engineering design and permitting, including additional investigations and evaluations to refine the cleanup action and enable detailed design work
  • 2027: Begin construction

Public Participation

Current Gas Works Park cleanup site Public Participation Plan

This plan includes information for the public regarding opportunities to get involved in the Site cleanup process. The outreach activities and mechanisms presented reflect Ecology’s current plans for keeping the public informed and for receiving information and comments from the public.

Site Information

Aerial view of Gas Works Park site operations, 1965
Aerial view of Gas Works Park site operations, 1965
Background
Formerly territory occupied by three indigenous communities (the Duwamish, Hachooabsh, and Shilsholes), the area surrounding the northern portion of Lake Union was settled by non-natives in the mid- to late 1800s. In 1907, construction of a manufactured gas plant was completed on the upland area of the Gas Works Park site to supply fuel for the growing population of Seattle. The plant operated until 1956.  Other industries (e.g., tar refining, bulk fuel storage, shipbuilding) also historically operated in the upland area.  These past industrial activities resulted in contamination of soil, groundwater and sediment.
Contamination in the upland area has been largely addressed through multiple cleanup actions completed between 1971 and 2020.  

Location
The Gas Works Park site is located at 2101 N Northlake Way, Seattle, Washington on Lake Union. It consists of approximately 21 upland acres (Upland Unit) and approximately 56 in-water acres (Sediment Unit). 

The City of Seattle owns the majority of the Upland Unit and the State of Washington owns the majority of the Sediment Unit.

Pictures







Site use restrictions called institutional controls are in effect

Institutional controls can be fences, signs, or restrictions on how the property is used. For instance, an institutional control may prohibit installing drinking water wells or disturbing a protective cap that isolates contamination. These restrictions keep the contamination contained and keep people from being exposed to the contamination. The controls are usually listed in environmental covenants recorded with the county.

Periodic reviews are required when institutional controls are required at a site. Ecology conducts reviews to make sure the controls remain effective and the cleanup still protects human health and the environment. We conduct periodic reviews about every five years.

Environmental Covenant

County Recording #: 20050505001726
County Recording Date: 5/5/2005

Restrictions/Requirements

  • Ongoing Maintenance of Remedy
  • Prohibit Removal or Alteration of Existing Buildings
  • Prohibit Soil Disturbance
  • Restrict All Ground Water Extraction/Well Installation

Restricted Media

  • Groundwater
  • Soil

Environmental Covenant

County Recording #: 20050505001727
County Recording Date: 5/5/2005

Restrictions/Requirements

  • Ongoing Maintenance of Remedy
  • Prohibit Removal or Alteration of Existing Buildings
  • Prohibit Soil Disturbance
  • Restrict All Ground Water Extraction/Well Installation

Restricted Media

  • Groundwater
  • Soil
Legal 14
Document Title Document Date Document Type
Gas Works Park - Consent Decree with Exhibits A-C - January 2024 1/25/2024 Consent Decree
Gas Works Park- Agreed Order 4th Amendment 12/14/2022 Agreed Order Amendment
Gas Works Park - Agreed Order 3rd Amendment 10/16/2017 Agreed Order Amendment
Gas Works Park - Agreed Order 2nd Amendment 4/26/2017 Agreed Order Amendment
Gas Works Park Sediments - Modification of Agreed Order DE 2008 3/13/2013 Agreed Order
Restrictive Covenant, City of Seattle - Gas Works Park & Seattle Police Harbor Patrol Property 5/5/2005 Environmental Covenant; Alternative Mechanism
Restrictive Covenant, City of Seattle - Gas Works Park 5/5/2005 Environmental Covenant; Alternative Mechanism
Gas Works Park - Amendment No. 1 To Consent Decree 5/1/2005 Consent Decree - Amendment
Gas Works Park - Agreed Order# 2008 3/18/2005 Agreed Order
Gas Works Park - AO Remedial Action 3/18/2005 Agreed Order
Gas Works Park - Consent Decree 11/30/1999 Consent Decree
Gas Works Park Consent Decree 10/22/1999 Consent Decree
Gas Works Park - Restrictive Covenant 1/1/1999 Environmental Covenant; Alternative Mechanism
Gas Works Park - AO Remedial Action 7/31/1997 Agreed Order
Public Information 29
Document Title Document Date Document Type
Gas Works Park Sediment Unit - Cleanup Action Plan, Consent Decree, SEPA DNS Response Summary - July 2023 7/27/2023 Responsiveness Summary
Gas Works Park Sediment Unit - Cleanup Action Plan Public Meeting - June 28, 2023 6/28/2023 Multimedia
Gas Works Park Sediment Unit - Cleanup Action Plan, Consent Decree, SEPA Fact Sheet TAGALOG - June 2023 6/8/2023 Fact Sheet\Public Notices
Gas Works Park Sediment Unit - Cleanup Action Plan, Consent Decree, SEPA Fact Sheet CHINESE - June 2023 6/8/2023 Fact Sheet\Public Notices
Gas Works Park Sediment Unit - Cleanup Action Plan, Consent Decree, SEPA Fact Sheet SPANISH - June 2023 6/8/2023 Fact Sheet\Public Notices
Gas Works Park Sediment Unit - Cleanup Action Plan, Consent Decree, SEPA Fact Sheet ENGLISH - June 2023 6/7/2023 Fact Sheet\Public Notices
Gas Works Park Sediment Unit - Remedial Investigation/Feasibility Study Response Summary - January 2023 1/5/2023 Responsiveness Summary
Gas Works Park Sediment Unit - RI/FS Public Meeting - November 2, 2022 11/2/2022 Multimedia
Gas Works Park Remedial Investigation/Feasibility Study and Agreed Order Amendment Fact Sheet - October 2022 10/14/2022 Fact Sheet\Public Notices
Gas Works Park Remedial Investigation/Feasibility Study and Agreed Order Amendment Fact Sheet - Tagalog 10/14/2022 Fact Sheet\Public Notices
Gas Works Park Remedial Investigation/Feasibility Study and Agreed Order Amendment Fact Sheet - Spanish 10/14/2022 Fact Sheet\Public Notices
Gas Works Park Remedial Investigation/Feasibility Study and Agreed Order Amendment Fact Sheet - Chinese 10/14/2022 Fact Sheet\Public Notices
Gas Works Park - Fact Sheet - Interim Action Fall 2017 9/11/2017 Fact Sheet\Public Notices
Gas Works Park - Fact Sheet- March 2017 3/17/2017 Fact Sheet\Public Notices
EJSCREEN Census Block Map Gas Works Park 12/29/2016 Fact Sheet\Public Notices
EJSCREEN Report Gas Works Park 12/29/2016 Fact Sheet\Public Notices
EJSCREEN ACS Summary Report Gas Works Park 12/29/2016 Fact Sheet\Public Notices
Gas Works Park Update 9/10/2014 Fact Sheet\Public Notices
Gas Works Park - Supplemental Investigation Begins at Gas Works Park March 2013 3/5/2013 Fact Sheet\Public Notices
Gas Works Park - Operations & Maintenance of remedial actions Nov 2012 fact sheet 11/8/2012 Fact Sheet\Public Notices
Gas Works Park - SEPA Fact Sheet (June 2012) 6/15/2012 Fact Sheet\Public Notices
Gas Works Park - Fact Sheet Hydrogeological Investigation 9/1/2010 Fact Sheet\Public Notices
Gas Works Park Fact Sheet Investigation Begins September 17 at Gas Works Park 9/1/2007 Fact Sheet\Public Notices
Gas Works Park Fact Sheet Investigation Begins September 19 at Gas Works Park 9/1/2006 Fact Sheet\Public Notices
Gas Works Park Fact Sheet consent decree amendment and Ecology review of site cleanup performance 5/1/2005 Fact Sheet\Public Notices
Gas Works Park Public Participation Plan 3/1/2005 Public Participation Plan
Gas Works Park Fact Sheet Draft agreed order 3/1/2005 Fact Sheet\Public Notices
Gas Works Park - Addendum to the Public Participation Plan 12/1/1999 Public Participation Plan
Gas Works Park Public Participation Plan 4/1/1997 Public Participation Plan
State Environmental Policy Act 7
Technical Reports 82
Document Title Document Date Document Type
Gas Works Park - Pre Remedial Design Workplan - Final - February 2024 3/7/2024 Site Specific Technical Document - other
Gas Works Park Sediment Unit - Final Cleanup Action Plan - July 2023 7/24/2023 Cleanup Action Plan
Gas Works Park- Remedial Investigation/Feasibility Study Text 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Tables 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Figures Sections 1-4 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Figures Section 5 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Figures Section 6 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Figures Section 7 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Figures Sections 8-13 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 1A-1C 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2A (1 of 3) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2A (2 of 3) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2A (3 of 3) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (1 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (2 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (3 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (4 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (5 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (6 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (7 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2B (8 of 8) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2C 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2D (1 of 4) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2D (2 of 4) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2D (3 of 4) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2D (4 of 4) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 2E 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 3A-3C 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 3D (1 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 3D (2 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 3E 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 3F-3J 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 4A-4F 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 5A-5C 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 5D 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 5E 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 5F (1 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 5F(2 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 6A 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 6B (1 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendix 6B (2 of 2) 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 11A-11C 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park- Remedial Investigation/Feasibility Study Appendices 12A-12B 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park - Remedial Investigation/Feasibility Study Appendices 13A-13B 1/19/2023 Remedial Investigation / Feasibility Study
Gas Works Park - Play Area IA Completion Report Text, Tables and Figures 1/13/2022 Interim Action Documents
Gas Works Park - Play Area IA Completion Report Appendices A-C 1/13/2022 Interim Action Documents
Gas Works Park - Play Area IA Completion Report Appendices D-H 1/13/2022 Interim Action Documents
Gas Works Park - Play Area IA Completion Report Appendices I-M 1/13/2022 Interim Action Documents
Gas Works Park - Play Area IA Completion Report Appendices N-Q 1/13/2022 Interim Action Documents
Gas Works Park- Play Area IA Monitoring Report 8/13/2021 Interim Action Documents
Gas Works Park - Monthly Progress Report - March 2019 3/19/2019 Progress Report
Gas Works Park - Monthy Progress Report - January 2019 1/31/2019 Progress Report
Gas Works Park - Monthly Progress Report - December 2018 12/3/2018 Progress Report
Gas Works Park - Interim Action - Sampling Analysis and Quality Assurance Plan - Addendum 4 11/15/2017 Interim Action Documents
Gas Works Park - Monthly Progress Report - October 2017 11/14/2017 Progress Report
Gas Works Park - Interim Action Workplan 8/1/2017 Interim Action Documents
Gas Works Park - Monthly Progress Report - June 2017 7/21/2017 Progress Report
Gas Works Park - Monthly Progress Report - May 2017 6/22/2017 Progress Report
Gas Works Park - Monthly Progress Report - January 2017 2/23/2017 Progress Report
Gas Works Park - Monthly Progress Report - December 2016 1/26/2017 Progress Report
Gas Works Park - Technical Memorandum - Play Area Injection Infrastructure-Groundwater Monitoring Well Network 12/19/2016 Site Specific Technical Document - other
Gas Works Park - Monthly Progress Report - November 2016 12/16/2016 Progress Report
Gas Works Park - Monthly Progress Report - October 2016 11/17/2016 Progress Report
Gas Works Park - Monthly Progress Report - September 2016 10/21/2016 Progress Report
Gas Works Park - Monthly Progress Report - August 2016 9/22/2016 Progress Report
Gas Works Park - Monthly Progress Report - July 2016 8/22/2016 Progress Report
Gas Works Park - Monthly Progress Report - June 2016 7/20/2016 Progress Report
Gas Works Park - Monthly Progress Report - May 2016 6/22/2016 Progress Report
Gas Works Park - Monthly Progress Report - April 2016 5/17/2016 Progress Report
Gas Works Park - Monthly Progress Report - March 2016 4/21/2016 Progress Report
Feasibility Study Bridging Document Appendix H 10/11/2013 Feasibility Study
Feasibility Study Bridging Document - Appendix F 10/11/2013 Feasibility Study
Feasibility Bridging Document Gas Works Park - 2013 10/11/2013 Feasibility Study
Gas Works Park - Supplemental Investigation Work Plan 3/13/2013 Site Specific Technical Document - other
Gas Works Park - Draft Supplemental Investigation Work Plan 2/27/2013 Remedial Investigation Work Plan
Gas Works Park - NE Corner Capping Project 90% design (Sept. 2012) 8/29/2012 Site Specific Technical Document - other
Gas Works Park - Surface Soil PAH (Jan 2010) 1/4/2010 Site Specific Technical Document - other
Gas Works Park - NE Corner Chemical Analysis Data Memo (May 2008) 5/5/2008 Site Specific Technical Document - other
Gas Works Park - NE Corner Investigtion Data Report (April 2008) 4/25/2008 Site Specific Technical Document - other
Gas Works Park Periodic Review 4/1/2005 Periodic Review (5 Year)
Gas Works Park Sediment Area - Area of Investigation 6/3/2004 Site Specific Technical Document - other
Gas Works Park - Supplemental Soils Testing Phase I Surface Soils Analysis 9/1/1985 Site Specific Technical Document - other
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.

Places to see print documents

  • Northwest Regional Office
    15700 Dayton Ave N
    Shoreline, 98133
    Please schedule an appointment to view print documents at this location.
  • Fremont Public Library
    731 N 35th Street
    Seattle, 98103
    This location may only have print documents available during open comment periods.

Contaminants 4

Contaminant Type
Soil
Groundwater
Surface Water
Air
Sediment
Bedrock
Halogenated Organics - Halogenated Organics C
Metals - Metals Priority Pollutants S
Non-Halogenated Organics - Petroleum Products-Unspecified C C
Non-Halogenated Organics - Polycyclic Aromatic Hydrocarbons C C
S
Suspected
C
Confirmed Above Cleanup Levels
B
Below Cleanup Levels
RA
Remediated-Above
RB
Remediated-Below
R
Remediated
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.