430 Pipeline Improvement Project

Project description

Construction work on pipeline improvements

The 430 Pipeline Improvement project will repair and upgrade portions of the large 42-inch diameter steel pipeline that runs four miles from Volunteer Park to Maple Leaf Reservoir in Seattle. The pipeline was built in the early 1900s and is part of the region’s drinking water system.


Construction for the 430 Pipeline Improvement project occurs inside of the underground pipe and above ground at multiple worksites (about 12) in the Maple Leaf, Ravenna, University District, Eastlake, and Capitol Hill neighborhoods.

What's happening now?

January 4, 2023 Update:

Contracting crews continue to perform construction activities as a part of the 430 Pipeline Improvement project. This work includes crews entering and exciting the pipeline through maintenance holes and utility hatches that have been installed to access the pipeline for cleaning and repair. This activity is taking place periodically in several neighborhoods in North Seattle:

University District: 

  • NE 56th and 12th Ave NE
  • NE 52nd and 12th Ave NE
  • NE 47th and 12th Ave NE 
  • NE 43rd and 7th Ave NE
  • NE Northlake Wy and 12th Ave NE
  • Harvard Ave E between Eastlake Ave E and Franklin Ave E
  • Broadway E between E Shelby St and E Hamlin St


  • 12th Ave NE and NE 66th St
  • 12th Ave NE near NE 75 St
  • 12th Ave NE near NE 62 St


  • NE 54th St and Ravenna Ave NE (Paving to permanently restore the roadway at this location is complete.)

Maple Leaf:

  • 1020 NE 82nd St — Maple Leaf Reservoir Park (Site restoration work continues at the park’s gate house. A fence outside of the gatehouse has been installed to allow crews and park users to remain safe during ongoing construction.)

Capitol Hill:

  • Federal Ave E and E Garfield St (Equipment will be attached to the maintenance hole from time to time to allow ventilation.)
  • Federal Ave E between E Lynn St and E Boston St (An access hatch has been installed, and street and vegetation restoration work is occurring.)
  • Federal Ave E and E Miller St (Curb and street restoration work has occurred and crews will return to complete vegetation restoration.)
  • Federal Ave E between E Boston St and E Newton St (Curb and street restoration work has occurred and crews will return to complete vegetation restoration.)

Portage Bay:

  • 10th Ave E and E Roanoke Ave
  • University Bridge at Portage Bay Place East (Work on and below the bridge to remove debris and fill a utility chamber with concrete is complete.)

Community benefits

The 430 Pipeline is a part of the region’s drinking water system. The improvement project will:

  • Increase the resiliency and reliability of Seattle’s drinking water system
  • Provide safer access to the pipeline
  • Protect against pipe erosion
  • Increase seismic resiliency
  • Improve fire suppression support
  • Add system redundancy
  • Provide greater pressure reducing and pressure relief capabilities

Community engagement

SPU is committed to providing timely information and updates on project activities. Updates may be available in multiple formats, including: the website, emails, and/or mailings. If you are interested in receiving email updates, please subscribe to the project email list.

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

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Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.