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Project area Project area 

Project area

King County built an underground storage tank on 23rd Avenue West in the Smith Cove area south of the Magnolia Bridge. When heavy rains fill the sewer pipes, a new underground structure at 32nd Avenue West will send excess sewer flows to a pipeline extending over half a mile under Magnolia Bluff to the storage tank. Excess stormwater and sewage will be stored in the tank until storms have passed. When there is room in the sewer pipes, stored flows will be sent through Interbay Pump Station to the West Point Treatment Plant

Project elements

Project elements include:

  • Underground structure at 32nd Avenue West to divert excess flows through a 3,000 foot pipeline extending under Magnolia Bluff to the Smith Cove area
  • An underground storage tank on King County property in the Smith Cove area south of the Magnolia Bridge
  • Equipment building at the storage tank site.
  • Restoration of the County’s property to provide access, on site stormwater management, and security.
  • Restoration of the right-of-way, Seattle Parks property, and temporary construction areas in accordance with permit and/or easement conditions 

Construction photos

rsz_18168917371_9d49fdc57f_zDetour for lower diversion structure along 32nd Avenue West

View more photos on our Flickr site  .

Operations phase

Contact us

Contact Monica Van der Vieren, community services, at:

 206-477-5502
 Monica.vandervieren
@kingcounty.gov