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Delridge Natural Drainage Project Updates

March 24, 2015

Over the past few months, the Delridge Natural Drainage Systems (NDS) project team has been working to refine the design details of the project. This design includes the siting of the natural drainage systems, the placement of street trees within the project area, addressing technical and cost constraints, and responding to input from neighbors.

Seattle Public Utilities has notified residents where street trees will be planted in the public right-of-way. The proposed planting is consistent with the City of Seattle’s tree canopy goals, and the design includes two-for-one tree replacement. This means that each tree that is removed to make room for the natural drainage systems will be replaced with two trees.

In the coming months, SPU will finalize the project’s design and prepare for construction. SPU will continue to work with project area residents on an individual basis to address any remaining concerns. Construction of the natural drainage system is scheduled to begin in late summer of 2015.

SPU continues to coordinate with the Seattle Department of Transportation (SDOT) Delridge Greenway Project where the planned greenway coincides with the Natural Drainage project on 17th Avenue SW between SW Kenyon and Henderson Streets. Learn more at the SDOT Delridge Greenway Project website.

October 23, 2014

The Washington State Environmental Policy Act (SEPA) Checklist and Determination of Non-Significance were issued on October 23, 2014. The environmental impacts of the proposed Delridge Natural Drainage Systems project have been analyzed and SPU has issued a Determination of Non-Significance:

October 2, 2014

The week of October 13, crews will be conducting geotechnical investigations and utility locates as part of the Delridge Natural Drainage System (NDS) project. The work will take place in areas along 17th Avenue SW from SW Kenyon Street to SW Henderson Street, and along SW Kenyon Street between 17th Avenue SW and 15th Avenue SW. Work hours are 7:00 a.m. to 5:00 p.m. Monday through Friday. Anticipated impacts include:

  • Noise from construction trucks, vehicles and equipment
  • Temporary traffic disruptions, including vehicle lane closures with construction flaggers, and closed sidewalks
  • Temporary reductions of some nearby on-street parking
  • Testing and utility markings on the ground

Project design continues to progress since the August 2014 Walk and Talk event. As we reach 60% design, we will have further updates to share with the project area regarding specific rain garden locations and other issues including: tree plantings, access issues, and schedule updates. Locations remain subject to change as the design team works through technical issues and cost constraints. SPU will continue to work with project area residents and the Seattle Neighborhood Greenway program to coordinate and finalize project design.

Additionally, the project team will be presenting at the Highland Park Action Committee meeting on October 22, 2014. The meeting starts at 7:00 p.m. and is held at the Highland Park Improvement Club at 1116 SW Holden Street, 98106. We hope to see you there!

August 13, 2014

Thanks to everyone who joined us during last night’s drop-in session. We had a great turnout and appreciate all your input and comments. In case you missed us last night, the meeting materials can be found below or on the Project Background page under “Project Documents”.

Throughout the rest of 2014 and into 2015, the project team will continue refining the design, including specific locations of the natural drainage systems. Construction is anticipated to begin in mid-2015. Please stay tuned for more information as design continues.

July 30, 2014

The Delridge Natural Drainage System (NDS) project is in early design. Join us at an informal drop-in session to:

  • Hear project updates from the design team
  • Review proposed design concepts and plantings
  • Chat one-on-one with the project team about the project

Tuesday, August 12
6:00 - 7:30 p.m.
Corner of 17th Ave SW and SW Elmgrove St

PDF Postcard Invite

June 4, 2014 – Upcoming public engagement opportunities

June 18, 7pm: Delridge Neighborhood District Council (Youngstown Cultural Arts Center, 4408 Delridge Way SW)

Late Summer: 30% Design Walk and Talk Tour of Project Area. More details coming soon.

March 20, 2014 - Roadside Rain Garden Locations Selected

Thanks to everyone who participated in our 2013 outreach events! We’ve received a wealth of input from you which will help ensure we design and build the best project possible. After several months of door-to-door visits, public meetings, surveys, emails and phone calls, we have identified the most-promising sites for natural drainage in the South Delridge neighborhood.

Based on community input through November 2013 and refinement of project scope due to cost considerations, these sites are the selected locations for roadside rain gardens (pdf): 17th Avenue SW from SW Kenyon to Henderson Streets; portions of the intersecting cross streets will be included based on performance, existing site conditions and project criteria. Please note that 17th Avenue SW between SW Henderson and Barton Streets has been removed from the project area due to a lack of cost-effectiveness.

In 2014, we will continue to gather your input about the design, including specific locations for rain gardens, access points to your home, preferences for plants, and other design issues. Construction is not scheduled to begin before spring 2015, but you may see survey or geotechnical crews in the area throughout the design of the project.

Sign up for future project updates.
How natural drainage filters pollutants (Sightline article)

Frequently Asked Questions (FAQs)

What kind of public input did we consider?

  • Input from the Nov. 19 open house
  • Input from the Oct. 19 Walk and Talk on the Block with residents
  • Neighborhood survey responses (more than 280). Read the survey results (pdf)
  • July 9 public meeting (more than 80 participants)
  • Input provided by community groups about:
    • Traffic safety concerns
    • Known drainage or sewer back-up problems, and
    • Places people wanted to walk and bike
  • Field observations of slopes, street widths, and plantings
  • Review of traffic volume, speed, and collision data

The City is already constructing a neighborhood greenway along 26th Avenue SW and is starting to study it for natural drainage improvements. Find out more.

What’s next?

  • Finalize the blocks where roadside rain gardens would be constructed.
  • Work with residents on those blocks to finalize design.
  • Continue to work with the team planning the neighborhood greenway to coordinate design and construction.

Does this mean that I won’t be able to park on the street?

Natural drainage projects in the public right-of-way are likely to affect some on-street parking. We know that parking and access from the street to the sidewalk is very important to residents, and we will carefully consider and address the impacts on every block where roadside rain gardens would be built.

Resident’s feedback about concerns regarding on-street parking is one of the pieces of input that helps to determine where to place natural drainage projects. If your block is identified for rain gardens, you will have opportunities during 2014 to provide input about the design.

Sign up for the Delridge/Highland Park email list to receive project updates.


Past Project Updates

November 19 and October 19, 2013

SPU held community outreach meetings to gather public input to help ensure we design and build the best project possible. After six months of various types of community outreach, SPU proposed locations for roadside rain gardens (pdf) based on the most-promising sites for natural drainage.

September 10, 2013

To make it safer for people of all ages and abilities to walk and ride bikes, a neighborhood greenway is planned in the Delridge/Highland Park area. As part of the project, natural drainage systems would be built along some parts of the route.

After analyzing data and reviewing public input, the most-promising greenway route has been identified as 17th Avenue SW from Roxbury to Kenyon or Holden Streets.

See more on this map (pdf)

The route would continue north on 21st Avenue SW and connect to the West Seattle Bridge Trail. More studies will be done to see how to best make this connection. Potential east-west neighborhood greenway routes are also being considered for implementation in the future.

A neighborhood greenway would reduce the speed limit to 20 miles per hour, add speed humps, and make it easier to cross busy streets. Natural drainage would include rain gardens along the edges of the streets to improve drainage and protect Longfellow Creek from pollution. Read the story of one creekside resident (pdf)

July 9, 2013

Surveys were mailed to residents living along the five possible routes (pdf) for a neighborhood greenway and 26th Ave SW Greenway, which is currently in construction. Results from the survey will help gauge community preference for locating natural drainage projects.

In addition, SPU and SDOT worked with White Center Community Development Authority (WCCDA) to improve outreach efforts. Ambassadors from the WCCDA made several door-to-door visits along each route to share information about the projects, encourage participation and invite the community to the July 9 public meeting.

View the July 9 Open House PowerPoint presentation (pdf)

View the July 9 Open House Display Boards (pdf)

October 4, 2012

SPU held an informative open house in Delridge presenting the overview of combined sewer overflow (CSO) problems into Longfellow Creek, strategies for reducing CSOs and project schedule. 

Project Contact

Don Anderson
(206) 233-1086