17th Ave NW Stormwater Improvements

Project description

Natural drainage systems use special soils and plants to capture rainwater, clean it, slow it down, and soak it into the ground.

Reducing street flooding and sewer problems in Crown Hill by building natural drainage systems

Some parts of the Crown Hill neighborhood experience street flooding or sewer backups. The 17^th Ave NW Stormwater Improvements Project will address the area with the largest, most frequent flooding problems.

Flooding and sewer problems happen during rainstorms on 17^th Ave NW because runoff from a large upstream area hits undersized, shallow pipes under the street. When the pipes fill, water bubbles up from inlets and ditches overflow into the intersection. Because the pipes are full, there’s nowhere for water to go until the system drains. A challenge for fixing the problem is that blocks downstream from the project area also experience flooding and sewer risks — if SPU were to simply increase the pipe sizes on 17^th, it could worsen the downstream problems.

This project will use a mix of pipe improvements and aboveground natural drainage systems to improve drainage while protecting downstream blocks. This will take pressure off the system and help it handle larger storm events.

Location

The project will focus on the area between NW 90^th Street and NW 85^th Street. Most of the work will be along 17^th Ave NW with some improvements on NW 87^th St and NW 90^th St.

Crown Hill Project site diagram. Click to enlarge.

What's happening now?

We’ve developed draft alternatives to address the stormwater and sewer problems. This has included studying site conditions, hearing from the community (PDF), and talking to SDOT about different possible ways to fit the necessary improvements into 17th Ave NW. 17^th Ave NW is a neighborhood greenway that provides important pedestrian bike and pedestrian connections for Crown Hill.

The project team is currently reviewing comments from the latest community engagement period this summer. We’re working to incorporate community feedback and new technical analysis as we move forward with the project. Thank you for your interest and participation in the 17th Ave NW Stormwater Improvements Project!

Community benefits

17th Ave NW is an important connection for students walking to and from Whitman Middle School. In wet weather, drainage problems make this route harder to use.

This project will significantly decrease the frequency of street flooding, a long-standing community concern. It will also decrease the risk of sewer backups to some homes on 17th Ave NW, and seek to address priorities from the City of Seattle’s recent community planning process, including the residents’ desire for pedestrian improvements and traffic calming on 17th Ave NW. Finally, increasing system capacity will help accommodate future growth.

What options are we looking at?

We are evaluating two possible project alternatives (PDF) that:

• Reduce the flooding at 17^th Ave NW and NW 87^th Street without increasing flooding risk to downstream blocks
• Are consistent with SDOT standards for safe and complete streets
• Provide pedestrian improvements and traffic calming

To view a more in-depth explanation of the project alternatives, please view this video. 

Community involvement

We're committed to providing timely information and updates on project activities. Updates may be available in multiple formats: this website, emails, drop-in sessions, briefings, and/or public meetings. There will be several opportunities for the public to engage and provide feedback during this process.

We’re currently working to incorporate community feedback and new technical analysis into two alternatives for the project site. These alternatives will be available for public review and comment later in the fall. Check back for more information about upcoming opportunities to get engaged. Also, please consider signing up for project updates.