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North Henderson


North Henderson project area.

What & Why?

What's happening now?

Construction will be underway on the Seward Park site between early 2015 and mid 2017. The park remains open, but parking will be affected. View parking map (pdf).

June 18, 2015

Summer is here! Safety and the construction site:

  • As warmer weather arrives, we want to remind you that construction will continue at Seward Park throughout summer. The construction activities will take place within the fenced area of the construction site (which covers Parking Lot #1 and the Tennis Courts), so please be aware of your surroundings.
  • Parking Lot #1 and the Tennis Courts will be closed through the duration of construction. Both will be reopened once construction is complete.

Look-ahead for construction activities:

  • Over the next few weeks, workers will continue to install utilities, such as piping and electrical components within the fenced area of the construction site. In July, the construction team will begin installing a new structure that will help control the CSO tank’s water levels.

Notice of Saturday work:

  • The construction team anticipates being on site on the following Saturdays: June 27th and July 11th from 9:00 a.m. to 5:00 p.m. to complete installation and demolition of piping infrastructure. There will be no construction activity on the 4th of July.

Additionally, starting in August 2015, workers will install new piping and buried structures in the 57th Avenue South right-of-way, adjacent to Martha Washington Park. The improvements in 57th Ave S will reduce CSO events at the existing outfall at the end of 57th Ave S.

Project goals and benefits

This project will reduce the frequency of sewage overflows into Lake Washington to no more than one per year per outfall (on average). SPU plans to complete two new underground storage facilities in North Henderson to store excess combined sewage and stormwater during major rain. The underground storage facilities are located offshore in the following locations:

  • Seward Park - view map of Basin 44 CSO improvements (pdf)
    The project includes additional piping, outfall replacement, with shoreline work and landscape improvements.
  • 57th Ave. S. near Martha Washington Park - view map of Basin 45 CSO improvements (pdf)
    The proposed underground facility for Basin 45 consists of a 16,000 gallon pipe and piping improvements.


Ask Us

Alan Lord, PE, Project Manager
(206) 233-1565

Please specify the project site with your comments:

  • Seward Park (Basin 44) or
  • 57th Ave. S. right-of-way (Basin 45)

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