Pipeline 1 Pressurization Program
In 2018, the Washington State Department of Health completed a Sanitary Survey of Tacoma Water’s system and identified a deficiency with Pipeline No. 1 (P1). P1 is one of two transmission mains that deliver drinking water from the Green River supply to Tacoma Water’s distribution system. Because portions of the pipeline are not fully pressurized, the Department of Health directed Tacoma Water to develop a long-term plan to address the issue and prioritize P1 improvements in the utility’s Capital Improvement program.
In 2021, Tacoma Water entered into a bilateral agreement with the Department of Health to fully pressurize Pipeline No. 1 by 2051. Tacoma Water then selected a consultant to identify capital projects needed to meet that goal. Through that process, the Canyonfalls Creek Pump Station project was identified as the highest-priority improvement.
Canyonfalls Creek Pump Station
The Canyonfalls Creek Pump Station will improve system reliability and support future P1 replacement projects. The facility will allow reverse operation of P1 by pumping up to 17 million gallons of water per day from McMillin Reservoir in South Hill to the Tehaleh and Bonney Lake service areas. Customers on the plateau typically receive water directly from the Green River Filtration Facility through P1.
Currently, P1 shutdowns only occur during wetter months and are generally limited to a duration of about a week because of existing system capacity constraints. As the area continues to grow, the new facility will improve operational flexibility and increase capacity during normal system conditions.
The proposed pump station site is located about 300 feet southwest of the intersection of Falling Water Boulevard East and 126th Street East near Bonney Lake.
A rendering of Tacoma Water’s Canyonfalls Creek Pump Station.
In addition to the pump station, the project includes several related improvements to support service continuity for customers along P1, including:
- Installation of two large-diameter inline valves
- Modifications to about six existing standpipes (above ground vertical vent pipes)
- Construction of more than one-quarter mile of offsite piping
These improvements provide risk-reduction and will facilitate simplified construction for upcoming P1 pipe replacement projects.
The project also includes replacement of about 300 linear feet of existing 54-inch centrifugally cast reinforced concrete pipe, installed in 1931 near Cumberland, with welded steel pipe. Removing the existing pipe will allow forensic testing of the concrete material and help guide future decisions for the broader P1 program.
Tacoma Water will deliver the project using the Progressive Design-Build method. Following approval from the Washington State Capital Projects Advisory Review Board, Tacoma Water selected Tapani, Inc. in conjunction with Windsor Engineers as the design-build team. Brown and Caldwell is serving as the owner’s advisor.
Design began in May 2025. Construction is scheduled to begin in October 2026 and be completed in March 2028.
Project Manager: Jason Moline, PE
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