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West Duwamish Wet Weather Storage

King County’s plans to build a wet weather storage facility to hold stormwater and wastewater that currently overflows into the Duwamish River during large storms.

Project description

Aerial map displaying location of the new storage facility and associated structures (two underground structures and two outfall/overflows) next to the Duwamish River.

King County will build a 1.25-million-gallon underground storage tank near the intersection of SW Michigan St and 2nd Ave SW to hold stormwater and wastewater that currently overflows into the Duwamish River during large storms. The water in the storage tank will then flow to the West Point Treatment Plant for treatment before it is safely released into Puget Sound. This storage tank will reduce overflows and pollution into the Duwamish River. The County will also build supporting infrastructure underneath West Marginal Way SW.

The project has recently reached the 90 per cent design milestone. At 90 per cent design, the project details are determined including equipment, architecture, landscaping, and contractor documents (design drawings and specifications). The project team is now focused on finalizing design details and preparing for construction, which will begin in 2025.

Project update

Soil sampling work near First Avenue South Bridge beginning April 8, 2024.

Starting as early as April 1, 2024, crews will begin visiting the project site to mark the locations of existing utilities. Crews will spend up to two business days drilling to collect soil samples. Once drilling is complete, crews will restore the surrounding surface. This work will help our team to better understand soil conditions below the project site.

This work will occur at the storage facility site. View project notice for more information.

Project design is nearing the finish line. Construction will start in 2025!

Explore our project newsletter and online open house to learn more about the West Duwamish Wet Weather Storage Facility project’s design progress, public art, work force development and community outreach.

Read the newsletter and online open house: publicinput.com/westduwamishenglish

Leer el boletín y Jornada de puertas abiertas en línea: publicinput.com/westduwamishspanish

Đọc bản tin và Nhà mở trực tuyến: publicinput.com/westduwamishvietnamese

閱讀時事通訊 和 網上開放日: publicinput.com/westduwamishtraditionalchinese

阅读时事通讯 和 网上开放日 : publicinput.com/westduwamishsimplifiedchinese

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