NE 40th Street Stormwater Trunk Extension
Uphill of Lake Sammamish, Redmond’s 40th Street stormwater trunk was built in the 1980s to intercept stormwater runoff from commercial properties and send it to the lower reach of Villa Marina Creek. However, after years of increased development and high velocity flows, the creek eroded, threatening Lake Washington’s water quality downstream.
Sound Transit’s planned light rail extension and related business and residential landowners are expected to further develop the area in coming years. Before this happens, the City sought to repair the creek’s erosion and bring into place more sustainable stormwater management infrastructure and practices.
Otak’s integrated specialists worked with the City to plan, design, and construct a suite of improvements that fix the creek, better collect and manage stormwater, and safely discharge to Lake Sammamish.
The project included 1,400 linear feet of new 42-inch HDPE pipe to a new, view-friendly, lake outfall, flow splitter and outfall dissipation structures, and stormfilters and modular wetland facilities to provide roadway water quality treatment. Otak’s design also included signal modifications, franchise utility relocations, and restoration of the NE 40th Street’s roadway and sidewalk.
Client: City of Redmond
Date Completed: 2015
Project Manager/Reviewer: Russ Gaston, Mandi Roberts
Otak Contract Amount / Total Project Cost: $2.5M
Type: Planning & design, transportation, water resources, construction management & inspection, surveying & mapping