Facility Site ID: 49919 Cleanup Site ID: 15139

Site Information

Aerial map of Duwamish Waterway Park, 2021
Aerial map of Duwamish Waterway Park, 2021
The Duwamish Waterway Park (Site) is located on the west side of the Lower Duwamish Waterway (LDW) in the South Park neighborhood of Seattle. The Site is approximately 1.7 acres and includes a play area, picnic area, and beach with river access.  Seattle Parks and Recreation owns and manages the park.


Site discovery and Initial Investigation


Preliminary soil investigations occurred at the site in 2014 and 2019, documenting soil contamination (see below).  Washington State Department of Ecology (Ecology) was notified of the discovery of contamination in spring of 2019, and an Initial Investigation was completed in January 2020.  During the Initial Investigation, Ecology evaluated environmental conditions at the property and reviewed all available data. The goal of the Investigation was to determine if the release may pose a threat to human health or the environment, and if further cleanup actions are needed.  Ecology tracks any site that is suspected or confirmed to be contaminated with hazardous materials, as required by the state’s cleanup law, the Model Toxics Control Act (MTCA), created by a 1989 voter initiative.


Ecology’s Confirmed and Suspected Contaminated Sites List


Following the Initial Investigation process the site was listed on the Confirmed and Suspected Contaminated Sites List in February 2020.  Remedial actions to date were conducted independently through Ecology's Voluntary Cleanup Program (VCP). 


Ecology’s Voluntary Cleanup Program


This site is under the VCP at Ecology Northwest Regional Office.  The VCP enables owners of contaminated sites to meet state cleanup standards independently and to receive technical guidance from Ecology during the process.

The VCP enables owners to work on a contractual basis rather than under an Ecology legal order.  Participants in the VCP pay fees to Ecology to cover the department’s costs for guidance and review.  VCP sites must meet the same cleanup standards as properties formally managed by Ecology under the MTCA.

A No Further Action determination may be reached with oversight by Ecology through the VCP. 

Current Status

Duwamish Waterway Park VCP Status – October 2021

In July 2020 City of Seattle Parks and Recreation (Parks) entered into the VCP (VCP Project Number NW3279) and requested a review and opinion on a Remedial Investigation (RI) of the Duwamish Waterway Park in July 2020.  Ecology requested additional information from Parks in August 2020 to draft our opinion letter.  Parks started renovation work at the site in October 2020.  Ecology received a revised RI in August 2021 which included additional information on interim actions.  Interim actions at the site included selective soil excavation, removal, and replacement with clean fill; construction of concrete pathways, placement of vegetation and laying of sod material, and installation of various capping technologies throughout the park.  Ecology provided an opinion on the RI and interim actions in early October 2021, detailing several information gaps for Parks to resolve as a condition for reaching a No Further Action determination under MTCA.  

Contaminants of Concern

Remedial actions completed between 2014 and 2021 identified the following contaminants of concern exceeding preliminary cleanup levels in soil:

• Arsenic
• Lead
• Mercury
• Metals-Other
• Other Halogenated Organics
• Other Non-Halogenated Organics
• Polychlorinated biPhenyls (PCBs)
• Carcinogenic Polycyclic Aromatic Hydrocarbons

Additionally, these contaminants of concern are also suspected in groundwater and surface water.  To date these contaminants of concern remain on the site.


What happens next?

Ecology’s opinion of the independent interim cleanup actions at the site documented several concerns about the potential impacts to human health and the environment.  Ecology’s opinion also described several information gaps regarding the components of an RI and Feasibility Study (FS)—site characterization and the establishment of cleanup standards for the selection and implementation of a cleanup action under MTCA.  Ecology’s opinion offers guidance and a path forward for Parks to address contamination at the site under MTCA, with the potential goal for a No Further Action determination.  Moving forward under the VCP, Ecology will provide technical assistance and opinions for Parks on sampling and/or work plans to resolve the information gaps identified, and Ecology will provide opinions on reports that include all the required components of an RI and FS.


Site Documents
Electronic documents are available for this site, click “View Electronic Documents” in the right-hand column. Click for instructions on how to submit a public records request.

Check out What’s In My Neighborhood to find out about other cleanups in your area. 

Voluntary Cleanup Program

This site is in our Voluntary Cleanup Program, which provides technical help to owners of contaminated sites.

Voluntary Cleanup Program customers pay fees to cover our costs for technical help and reviewing cleanup reports. Sites in this program must meet the same cleanup standards as sites Ecology manages under legal orders.

Legal 1
Document Title Document Date Document Type
Duwamish Waterway Park - Early Notice Letter 2/5/2020 Early Notice Letter
Technical Reports 21
Document Title Document Date Document Type
Duwamish Waterway Park / Addition - SHA Notification Letter 6/15/2022 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Draft RI/FS Workplan 4/26/2022 Remedial Investigation Work Plan
Duwamish Waterway Park—NW3279 Remedial Investigation Report Version 3 Additional Information 10/8/2021 Remedial Investigation Report
Duwamish Waterway Park—NW3279 Email Correspondence RI V3 Request for Additional Information 10/8/2021 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Soil Sampling Report Park Bench Sliver Area 9/30/2021 Site Specific Technical Document - other
Duwamish Waterway Park—NW3279 Email Correspondence Confirmation Sampling Questions 9/29/2021 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Project Meeting, Progress, Next Steps Sept07 2021 9/7/2021 Progress Report
Duwamish Waterway Park—NW3279 Remedial Investigation Report Version 3 Appendices 8/20/2021 Remedial Investigation / Feasibility Study
Duwamish Waterway Park—NW3279 Remedial Investigation Report Version 3 8/20/2021 Remedial Investigation / Feasibility Study
Duwamish Waterway Park—NW3279 Project Meeting, Progress, Next Steps Mar22 2021 3/22/2021 Progress Report
Duwamish Waterway Park—NW3279 Project Meeting, Progress, Next Steps Jan27 2021 1/27/2021 Progress Report
Duwamish Waterway Park—NW3279 Email Correspondence Preliminary Feedback 4 10/30/2020 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Email Correspondence Preliminary Feedback 3 10/8/2020 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Email Correspondence Preliminary Feedback 2 9/15/2020 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Email Correspondence Preliminary Feedback 1 8/10/2020 Site Specific Administrative Document - other (Administrative correspondence)
Duwamish Waterway Park—NW3279 Terrestrial Ecological Evaluation form 7/1/2020 Terrestrial Ecological Evaluation
Duwamish Waterway Park—NW3279 Remedial Investigation Report 6/23/2020 Site Specific Technical Document - other
Duwamish Waterway Park - Initial Investigation Field Report 1/28/2020 Initial Investigation Report
Duwamish Waterway Park - March 2019 Soil Sample Results 3/1/2019 Site Specific Technical Document - other
Duwamish Waterway Park - January 2019 Soil Sample Results 1/28/2019 Site Specific Technical Document - other
Duwamish Waterway Park - July 2014 Soil Sample Results 7/20/2014 Site Specific Technical Document - other
Voluntary Cleanup Program 1
Document Title Document Date Document Type
Duwamish Waterway Park—NW3279 VCP Opinion Letter 10/27/2021 VCP Opinion on Site Cleanup – 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.

Contaminants 8

Contaminant Type
Soil
Groundwater
Surface Water
Air
Sediment
Bedrock
Metals - Metals - Other C S S
Halogenated Organics - Polychlorinated biPhenyls (PCB) C S S
Non-Halogenated Organics - Polycyclic Aromatic Hydrocarbons C S S
Metals - Arsenic C S S
Metals - Lead C S
Metals - Mercury C S S
Halogenated Organics - Other Halogenated Organics C S S
Non-Halogenated Organics - Other Non-Halogenated Organics C S S
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.