Longfellow Creek Natural Drainage System (NDS) Project

Photo of a street with natural drainage system
Example of a natural drainage system.

Project Description 

Enhancing Our Communities with Natural Drainage Systems and Pedestrian Improvements 
Seattle Public Utilities (SPU) will construct natural drainage systems (NDS) at 3 sites in the Longfellow Creek basin. Natural Drainage Systems are built in the roadway shoulder (the space between the street edge and the property line) and are filled with deep-rooted plants and spongy soils that temporarily hold and clean polluted stormwater from streets and sidewalks before the stormwater enters our waterways.

Natural drainage systems offer multiple community benefits, including:

  • Increased landscaping
  • Lower risk of flooding
  • Creation of habitat along our streets
  • Healthier creek ecosystems
  • Traffic calming
  • More street trees
  • Pedestrian improvements

SPU is partnering with Seattle Department of Transportation on this project to provide pedestrian improvements at 24th Ave SW between Thistle and Barton streets and the SW Kenyon St pedestrian bridge at 24th Ave SW, and this project is funded in part by the Levy to Move Seattle. 

Through the City of Seattle's Public Art Program, we're adding artwork at the SW Kenyon St site. The artwork along with the pedestrian improvements and new natural drainage systems were designed to create space for the community to connect with neighbors and the surrounding habitat.

Location

This project includes three locations, which were selected based on a variety of factors that included community input, recurring drainage and flooding issues, technical feasibility, and more.

  • 24th Ave SW (between SW Thistle and SW Barton St)
  • Sylvan Triangle (Sylvan Way SW between SW Orchard St and Delridge Way SW)
  • SW Kenyon St (The Longfellow Creek pedestrian bridge at 24th Ave SW)

Visit site map to see where each of the sites are in the Longfellow Creek area and see below for more information about the final design and anticipated construction impacts for each of the sites.

24th Ave SW (Between SW Thistle St and SW Barton St)

SPU will install natural drainage systems from SW Cloverdale St to SW Barton St, which will help improve stormwater drainage, slow down traffic, as well as remove pollutants from stormwater runoff to improve water quality in Longfellow Creek, a salmon-baring creek.

We know that many residents highly value pedestrian safety and sidewalks, and we are excited to partner with SDOT to install a sidewalk along the west side of 24th Ave SW between SW Thistle and SW Barton St as part of this project.

To view the planned work near your home, please review the Final Design and Info for 24th Ave SW and visit the Online Open House.

What to Expect During Construction?

We won’t have a start date for construction at the 24th Ave SW Site, until we have a contractor onboard. We’ll provide an update with more information once we get the contractor’s schedule and project plan.

In the meantime, residents can expect the following once construction begins near their home:

  • Work will generally occur during weekday, daytime hours
  • Construction noise, dirt, dust, and vibrations
  • To minimize disruption, work will generally be done in segments moving along 24th Ave SW
  • Parking restrictions and temporary lane closures near the work area
  • Temporary blockage of driveway access during some construction activities. When possible, the contractor will work to reopen access during nights and weekends.
  • Materials and equipment staged in the along the road edge near construction activities
  • The contractor will work to maintain access for delivery services, garbage/recycling/compost pick-up, and emergency vehicles. In some instances, mailboxes may be temporarily relocated during construction to facilitate deliveries. 
  • Some residents may experience brief, temporary water service interruptions to facilitate water meter relocation. Advanced notice will be provided prior to planned water outages.
  • Removal of street trees in areas where NDS and sidewalks will be installed and installation of new street trees along 24th Ave SW in accordance with SDOT's Urban Forestry requirement to improve Seattle's tree canopy, which has many benefits, including improving air and water quality. 
  • Installation of curb and gutters and driveway aprons along 24th Ave SW as well as final street pavement restoration, which may require 24-hr/day closures to allow for curing

If you have items in the public right-of-way (e.g. plantings, rockeries, and/or fences) that you would like to keep, please remove them prior to construction.

Maintenance and Care

SPU is responsible for all maintenance needs of the natural drainage systems, which will include general upkeep of the NDS plantings, checking that the NDS is property functioning, removing sediment, and replacing or removing plantings and trees in the NDS, if needed. You will not be asked to pay for or perform any maintenance related to the NDS.

Sylvan Triangle (Sylvan Way SW between SW Orchard St and Delridge Way SW)

SPU plans to install a large natural drainage system in the public right-of-way on Sylvan Way SW near Home Depot.

To view the planned work at this site, please review the Final Design and Info for Sylvan Way SW and visit the Online Open House.

What to Expect During Construction?

During construction, there will be increased construction traffic as well as materials and equipment in the project area.

While most of the work will be contained to the grassy area between Sylvan Way SW and the Home Depot parking lot, the contractor will require temporary traffic impacts to perform work near the road edge.

The project team will coordinate with other construction activities in the area to minimize impacts to the extent possible.

We will not have an expected start date for construction at the Sylvan Triangle Site until we have a contractor onboard.

We’ll provide an update with more information once we get the contractor’s schedule and project plan.

SW Kenyon St (The Longfellow Creek pedestrian bridge at 24th Ave SW)

SPU has partnered with SDOT and the Office of Arts and Culture to develop planned improvements near the intersection of SW Kenyon St and 24th Ave SW. These improvements include:

  • New walkway, bridge, and boardwalk to make it easier for people to get to nearby schools, homes, and bus stops
  • Natural drainage systems to reduce pollution in Longfellow Creek
  • Art installation to enhance the space and connect community to the creek

To view the planned work at this site, please review the Final Design and Info for SW Kenyon St and visit the Online Open House.

What to Expect During Construction?

We won’t have a start date for construction at the SW Kenyon St site, until we have a contractor onboard. We’ll provide an update with more information once we get the contractor’s schedule and project plan.

In the meantime, you can expect the following once construction begins at this site:

  • Work will generally occur during weekday, daytime hours
  • Construction noise, dirt, dust, and vibrations
  • Parking restrictions and temporary lane closures near the work area
  • Pedestrian detours will be in place
  • The project team is working with the nearby schools

What's Happening Now?

SPU finalized design and recently selected a contractor. We are working with the contractor to prepare for construction to begin at one of the three sites as soon as fall 2021.

Once we have the contractor's schedule, we'll know more about which site the contractor will start work at and we'll be in touch with more details about anticipated start date, estimated duration of work at each of the sites, and construction impacts.

In the meantime, please visit our Online Open House to learn more about the final designs for each of the sites and share your feedback to inform our upcoming construction communications.

Also, please sign up to receive project email updates to stay informed about this project throughout construction.

Community Benefits

This project will improve water quality in Longfellow Creek, as well as improve stormwater drainage, slow down traffic, provide pedestrian improvements, and beautify streets.
The project will also help the City of Seattle achieve its goal of managing 700 million gallons of stormwater runoff using green infrastructure by 2025.

Community Engagement

Thank you to everyone who shared their valuable feedback throughout planning and design! We have finalized the project design and are preparing for construction. 

Please visit our Online Open House to learn more about the project and share your questions about construction.

If you're interested in learning more and finding out about upcoming construction activities, please sign up to receive project email updates.

Art at 24th Ave SW & SW Kenyon St

Through the City's Public Art Program, Portland-based artist, Brian Borrello, developed an art installation for the SW Kenyon St site.

The artist's goals are to make this place interesting for the community to visit and for the art to offer something unexpected, thought-provoking, and perhaps a little magical. This site is where life forces are nourished by the creek, where neighbors can connect with each other while they pass through, and where community can experience the natural world and its often-unseen processes.

Below is the artist’s proposed concept. Visit our online open house to learn more about the proposed art.

rendering of proposed art

Schedule

Past Work

  • Initial outreach to gather community input to inform site selection
  • Concept development for potential natural drainage systems sites
  • Design development for the three selected sites
  • Design phase community outreach, which included hosting an Online Open House, an online questionnaire, email list updates, mailers, meetings with residents, and more

Early to Mid-2021

  • Finalize project design and perform the construction contracting process
  • Pre-construction outreach including anticipated impacts for each site as well as construction schedule and sequencing information once provided by the contractor

Late 2021 to Mid-2023

  • Construction on this multi-site project to occur with the contractor expected to work on one site at a time
  • Provide ongoing construction updates to the community

Background

Natural drainage systems slow stormwater and filter out pollutants before they can harm our creeks and other waterways. Keeping pollutants out of our water is important for fish, aquatic life, and people.

Building a natural drainage system in Longfellow Creek basin is part of the Plan to Protect Seattle's Waterways. SPU used to call these "roadside rain gardens" but now calls them "natural drainage systems" or "NDS."

Why Longfellow Creek? Longfellow Creek is a salmon-bearing urban creek with degraded water quality adjacent to where people live, work, and play. Stormwater picks up pollutants from streets-including oil, heavy metals, and fertilizers-every time it rains and flows into the creek through ditches or pipes. This project will remove pollutants from the stormwater before it reaches the creek.

Funding Information

This project is paid for in part by the King County Flood Control District and the Levy to Move Seattle. Art at the SW Kenyon St site is through the City of Seattle's Public Art Program.