430 Pipeline Improvement Project

Project description

Construction work on pipeline improvements

The 430 Pipeline Improvement Phase 2 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.

Phase 1 of the project involved water system upgrades, installation of 14 new pipe accesses, and rehabilitation of 30% of the pipeline. Phase 2 will continue the work started in Phase 1 by rehabilitating the remaining 70% of the pipeline. All work for Phase 2 will be underground. However, access to the pipeline is required from the road surface and staging of equipment for this work will also occur in the roadway.


Construction for the 430 Pipeline Improvement Phase 2 project occurs inside of the underground pipe and requires above ground staging at multiple work sites. See the pipe alignment map for the approximate location of the underground pipe. Work will take place at multiple locations along this alignment in the Maple Leaf, Roosevelt, University District, Portage Bay, and Capitol Hill neighborhoods.

What's happening now?

Construction for the last work site in the Phase 1 project is underway at 10th Ave E and E Roanoke Ave, and is expected to wrap up by early summer 2024. All other Phase 1 sites have completed construction.

The Phase 2 project has completed the design phase and is preparing to enter construction as early as fall 2024. Individual notices for each work site will be sent by mail to the impacted areas prior to construction.

Community benefits

The 430 Pipeline is a part of the region’s drinking water system. Phase 2 of the project will:

  • Increase the resiliency and reliability of Seattle’s drinking water system
  • Protect against pipe erosion

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.

Fall 2024 - Fall 2026

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.