​Location of siphon to be decommissioned, under new stream channel image

​Location of siphon to be decommissioned, under new stream channel

Sanitary Sewer Replacement (2015)

​Project Overview: EU-0170

This is the annual sanitary sewer replacement project that will occur on 21st Street between Wilson and Donovan avenues, Donovan Avenue between 21st and 22nd streets, 22nd Street between Donovan Avenue and Old Fairhaven Parkway, and Old Fairhaven Parkway between 21st and 22nd streets.

This project will remove two sanitary sewer siphons from the conveyance system. One is beneath the newly daylighted section of Padden Creek, and the other is beneath the former Padden Creek tunnel in 22nd Street. Siphons require extensive maintenance, and the location next to and under a salmon bearing stream increases the risk of possible spills and complicates future maintenance activities.

The greatest challenge will be modifying the former Padden Creek tunnel to allow the new sanitary sewer to pass through it. The sanitary piping will be encased in concrete and contained in a casing.


FAQ: Sewer Spill (PDF)

Project Details

  • Status - Complete
  • Contract Awarded - 1/25/2016
  • Contract Amount - $1,291,745.64
  • Contractor - Strider Construction
  • Completion Date - 2/22/2016
  • Final Contract Amount - $1,363,787.42
  • Vicinity Map

Affected Neighborhoods

    Happy Valley

Participating Departments

    Public Works


​Craig Mueller, P.E.
Project Engineer
Phone: (360) 778-7922
Public Works Contacts