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West Duwamish Trail Project

Update: February 23, 2015

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Construction Updates

The West Duwamish Trail Project is now complete!

Thank you for your patience throughout construction. Please join us in celebration at an event on Saturday, March 7, from 10 AM – 12 PM at the corner of S Portland Street and 8th Avenue S.

Over the past six months crews have:

  • Cleared an area of heavy vegetation at the west end of S Portland Street
  • Installed a new drainage system on S Portland Street between West Marginal Way S and 8th Avenue S
  • Paved an asphalt trail for pedestrians and bicyclists that extends the existing Duwamish Trail
  • Installed new lighting along the trail route, improving visibility for pedestrians, bicyclists and vehicles
  • Paved the roadway on S Portland Street between West marginal Way S and 8th Avenue S (much of which was previously unsurfaced)
  • Built new concrete driveways for vehicles to access S Portland Street and 8th Avenue S

Questions? Contact Art Brochet, Project Communications Lead, at or 206-684-8424.

Si usted necesita esta información traducida al español por favor llame al 206-733-9990.


Project Materials

Click to view updated project materials:

Project Description

The Seattle Department of Transportation (SDOT) is designing an extension of the West Duwamish Trail, which now ends at S Holden Street and 2nd Avenue S. This extension will create a protected connection to 8th Avenue S and S Kenyon Street, where an existing bicycle route continues south on 8th Avenue S through South Park and on to the Green River Trail.

The selected alignment is along the east side of W Marginal Way South, on the south side of S Portland Street and on the west side of 8th Avenue S.

As part of this project, S Portland Street will be paved with asphalt between 2nd Avenue S and 8th Avenue S and drainage will be installed on S Portland Street which will connect to the future Seattle Public Utilities pump station. (Currently there is no pavement on S Portland Street west of 5th Avenue S or east of 7th Avenue S.)

Project Elements and Benefits

  • 10-foot trail for pedestrians and bicyclists
  • New asphalt pavement on S Portland Street (much of which is currently un-surfaced)
  • A storm water drainage system on S Portland Street
  • Lighting along the trail, improving visibility for pedestrians, bicyclists and vehicles
  • Concrete driveways for vehicles to access S Portland Street and 8th Avenue S

As a part of overall planning for the area, Seattle Public Utilities (SPU) is designing the drainage system to connect to the future pump station and water quality facility on 7th Avenue S near S Riverside Drive. The drainage system will include storm drain inlets and catch basins along South Portland Street. Although this system will not be fully effective until the pump station is completed, it will help to reduce the potential for standing water along the roadway and trail route.

Trail & Roadway Description

The trail on S Portland Street will be 10 feet wide, with a 3.5-foot-wide buffer between it and the new curb (to the north) and 3 feet of distance to the private property lines (to the south). Driveways that cross the trail will be paved with concrete.

The new paving on S Portland Street will provide an 11-foot westbound lane and a 13-foot eastbound lane. The roadway will be bordered by the new concrete curb on the south side to the (thickened) asphalt edge on the north side. The public right-of-way to the north of the new asphalt surface (approximately 18-foot wide) will remain undisturbed, and may still be used for parking.

The trail on 8th Avenue S will be 10 feet wide with a 2-foot-wide separation from the private properties. Parking will be eliminated on the west side of the street between S Portland Street and S Kenyon Street, leaving two 11-foot driving lanes and a seven-foot parking lane on the east side of the street.

Traffic/signage changes after completion:

A four-way stop is planned for the intersection of S Portland Street and 5th Avenue S. There will also be a stop sign for northbound and southbound traffic on 7th Avenue S.

Signage will be installed on the trail warning bicyclists that they are entering an industrial area, to use caution, and maintain a safe speed.

Parking changes after completion:

The south side of S Portland Street and the west side of 8th Avenue S will no longer be available for parking. Signage to establish new load/unload zones and/or parking restrictions may be established in places on the north side of S Portland Street and on the west side of the 8th Avenue S, depending on circumstances and the desires of adjacent property owners.

Project Schedule

Construction is scheduled to begin on Monday, July 7 and is anticipated to last approximately six months. The full construction schedule is currently under development but the first activity will be drainage installation on S Portland Street between 5th Avenue S and 7th Avenue S.

SDOT will work closely with businesses and residents in the area to minimize impacts throughout construction. The Construction Communication Officer (CCO) will provide email updates and be available to answer questions for the duration of the project.

Project history and development

The project was originally planned to be along S Holden Street, one block north of the route eventually selected. Preliminary observations raised several concerns, so alternative routes along S Austin, S Portland, and S Chicago Streets were considered. The S Portland Street route was selected by SDOT and endorsed by Seattle’s Freight, Bicycle and Pedestrian advisory Boards, as well as the South Park Neighborhood Association.

SDOT teamed with SPU to expand the scope of the project to address drainage needs of the community, and was able to identify additional funding to provide paving as well.

Addition of 8th Avenue S, from S Portland Street to S Kenyon Street

In December of 2012 members of the South Park Neighborhood Association proposed extending the West Duwamish Trail still further, from S Portland Street and 8th Avenue S to S Kenyon Street and – if funds were available – east along S Kenyon Street to 10th Avenue S. This proposal was selected by the Greater Duwamish District Council as one of three (out of eight) for further consideration by SDOT under the Neighborhood Street Fund program. After preliminary engineering and cost analysis, it was selected as the Council’s top choice to compete for funding. On September 9th the Bridging the Gap Oversight Committee selected the 8th Avenue S element as one of 12 projects city-wide to receive funding.

Environmental aspects and project permitting

SDOT developed a SEPA Checklist for the project which includes extensive analysis of subsurface soil conditions and contaminants. Due to the area’s long history as a center of industrial manufacturing, and the extremely shallow water, particular care will be taken during construction to manage and dispose of excavated materials.

On August 1, 2013, the SEPA Checklist was distributed to City, State and Federal agencies, affected tribes and businesses in the vicinity of the project. Since that time SDOT decided to extend the multi-use trail project two blocks south along 8th Avenue S. On October 7, 2013 SDOT issued an Addendum to the SEPA Checklist describing new elements of the project and additional information used in the analysis.


Funding for the project originated with the 2008 Parks and Green Spaces Levy. Additional funding is being provided by the Bridging the Gap Neighborhood Street Fund. This addition was supported by Seattle’s Southeast District Council as its highest priority project and was selected (as one of 12 projects, city-wide) by the Bridging the Gap Oversight Committee.


Prior Project Briefings

August 21, 2012

Seattle Freight Advisory Board

August 29, 2012

Machinists Inc.
NW Laboratories
West Coast Wire & Rope
Gear Works
Flamespray NW
Cain Bolt & Gasket

September 12, 2012

Seattle Pedestrian Advisory Board

October 3, 2012

Seattle Heat Treaters
Independent Metals

October 3, 2012

Seattle Bicycle Advisory Board

November 6, 2012

Seattle Tri-Modal Advisory Committee

November 15, 2012

Jon’s Recycling
Washington Lifttruck
Custom Crating
Fire King
Gil’s Aluminum and Shell Core
Harbor Island Supply

November 20, 2012

South Park Community Council’s Transportation Committee

December 3, 2012

Graham Trucking
Pacific Western Agencies

December 11, 2012

South Park Community Council

September 17, 2013 South Park Community Council’s Transportation Committee

February 11, 2014

Open House from 5PM to 7PM
 (8201 10th Ave South)

May 13, 2014 South Park Neighborhood Association briefing
(8201 10th Avenue S)
June 10, 2014 South Park Neighborhood Association briefing
(8201 10th Avenue S)
June 26, 2014 Meet the Contractor Event

Nearby Projects

Riverside Park Restoration Project
The Seattle Parks Department (with the assistance of the Seattle Parks Foundation and the Port of Seattle) is extending the pocket park at the 8th Avenue S street end on the West Duwamish Waterway along S Riverside Drive. click HERE for more information

Pump Station and Water Quality Facility
SPU is planning a Pump Station and Water Quality Facility to be located at 7th Avenue S and S Riverside Drive. This facility will reduce flooding in the industrial area near the River and improve water quality of runoff that is discharged to the Duwamish River. The project team is evaluating options for the water quality treatment and timing for construction will depend on which option is selected. Click HERE for more information.

Contact Us

Email Updates:

If you would like to receive periodic notices about design and construction activities in the future by email Click here

Project Contact:

George Frost
Construction Communication Officer

Terry Plumb
Project Manager


Si usted necesita esta información traducida al español por favor llame al 206-733-9990

Kung kailangan ninyong  isalin sa Tagalog ang  impormasyong ito,  paki-tawag lang sa 206-733-9990.

Nếu quý vị cần thông tin này chuyển ngữ sang tiếng Việt, xin gọi số 206-733-9990.

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