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West Duwamish Wet Weather Storage Facility

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

site rendering of the future West Duwamish Wet Weather Treatment Facility.

King County will build a 1.25-million-gallon underground storage facility 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 facility will then flow to the West Point Treatment Plant for treatment before it is safely released into Puget Sound. This storage facility 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 60 per cent design milestone. At 60 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

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:

Leer el boletín y Jornada de puertas abiertas en línea:

Đọc bản tin và Nhà mở trực tuyến:

閱讀時事通訊 和 網上開放日:

阅读时事通讯 和 网上开放日 :

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SAVE THE DATE! Green Jobs Symposium and Career Fair

When: March 6, 2024, 4p.m. - 7 p.m.

Where: South Seattle College – Georgetown Campus, 6737 Corson Avenue South, Seattle, WA 98108

You are invited to meet in-demand employers in the fields of clean water, sustainable building, and green jobs! Attend and participate in hands-on demonstrations, break-out sessions, networking, resume help, and other skill building activities.

This event is free and open to the public, including people in all stages of careers and education. Registration is recommended, sign up by March 1st for a printed name tag

Sponsored by: King County Wastewater Treatment Division and Sustainable Building and Science Technology program at South Seattle College – Georgetown

Previous project updates

Consultants, contractors & suppliers: learn about upcoming construction projects including the West Duwamish Wet Weather Storage Facility.

Project location