Mouth of Duwamish Program Management and Owner Advisory Services

King County is developing the Mouth of Duwamish Combined Sewer Overflow Control Program, anticipated to be their largest CSO control project, controlling up to eight CSO outfalls. This program will plan, design, and construct facilities to control five King County CSO outfalls. The five CSO outfalls include the Chelan Avenue, Hanford #2, Lander Street, Kingdome, and King Street. Three Seattle Public Utility (SPU) CSO outfalls, SPU 99, SPU 107 and SPU 111, are being evaluated for potential incorporation into the Mouth of Duwamish project.

This program is vital to the County’s compliance with the Clean Water Act and meeting its obligations in a 2013 Federal Consent Decree. It will also make major advances in equity and environmental quality for the area.

Parametrix is providing program management and owner advisory (PMOA) services, including: 

  • Overall program management
  • Master program schedule development
  • Project delivery planning including assisting King County with alternative delivery contracting
  • Independent cost estimating and program cost estimating
  • Program equity planning
  • Preparation of bridging documents for future design-build contracts

As part of the Owner’s representative team for this multi-decade separation of wastewater and stormwater systems, Parametrix is guiding the program through the Envision Sustainability process, ensuring any and all design efforts are informed by proper climate science to determine design values, determining how to decarbonize the systems involved such as pump stations, and  identifying how to decarbonize the construction process and the materials themselves.

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