NE 40th Street Stormwater Trunk Line Extension

Vicinity Map

Location:  NE 40th Street, from 172nd Ave NE to Lake Sammamish 

Project Phase: Preliminary Design

Estimated Timeline: Preliminary design has begun, with construction expected to begin in the Fall of 2018.

Contact: Mike Haley, 425-556-2843

Page Last Updated: 03/28/17

Neighborhood Meeting
April 5, 2017, 6:00 pm to 9:00 pm
Join us at the VFW Hall (4330 148th Avenue NE) to learn more about this project. Click here for more information.

The City of Redmond has adopted an ambitious vision to accommodate significant urban growth in the Overlake area, and the NE 40th Street stormwater trunk extension is an important step in implementing that vision.

The existing NE 40th Street Stormwater Trunk was built in 1983 to convey uncontrolled stormwater flows to the lower reach of Villa Marina Creek, protecting its upper reaches from erosion. Since that time, the City has worked with Villa Marina Condos to address flooding and repair erosion damage in the creek. The City’s current NPDES permit requires that new development and redevelopment projects provide flow control to protect streams like Villa Marina Creek. Any new development requires construction of vaults or a direct pipe to the lake. By extending the existing stormwater trunk into Lake Sammamish, Villa Marina Creek will be protected from high flows without harming the lake.

Key objectives of this project are to collect all stormwater from the watershed and to facilitate a greater percentage of direct discharge to Lake Sammamish, while maintaining and enhancing base flows to Villa Marina Creek. This will improve water quality and flow conditions in Villa Marina Creek while also reducing the need for on-site detention. The watershed served by the stormwater trunk is home to the Overlake Transit Center, East Link light rail access (opening in 2023), and other employment uses in the Overlake area, along with varying densities of residential development and City Streets.