Tolt 16-inch natural gas line
Phase 1 complete

Project overview

Due to a growing demand for natural gas, PSE's 8-inch high pressure natural gas line serving northeast King County is nearing its capacity during cold winter days, when people use more energy to stay warm. The system's capacity constraints impact our ability to supply natural gas at an adequate pressure to reliably serve more than 27,000 residential, commercial and industrial customers in the Woodinville, Bothell, Kenmore, Kirkland and unincorporated King County areas.

In order to maintain the reliability of the natural gas system in the area and ensure we can continue to provide our customers with dependable service, PSE began upgrading the natural gas system in northeast King County in 2015. The scope of phase 1 & 2 includes building approximately four miles of 16-inch high pressure natural gas pipeline and a facility where natural gas is metered, reduced in pressure, and injected with a strong odorant called mercaptan, which gives the gas its familiar rotten-egg smell. The first phase of this project was completed in 2018. See below for details regarding the completed phase and the additional work planned for a future date.

Project timeline:

  • Phase 1 - Complete
    Construction of 2.8 miles of 16-inch natural gas pipeline along the existing SPU utility corridor, between Mink Rd NE and 155th Ave NE. This phase began construction in 2015. Construction of the remaining 1,800 feet commenced in June 2018.

  • Phase 2
    Construction of 1.2 miles of 16-inch natural gas pipeline along the existing SPU utility corridor between 216th Avenue NE and Mink Road NE, where it will connect to the segment of pipeline constructed in Phase 1. Construction of a new gate station is also included in this phase. Construction for this phase is planned for 2022 and timings are based on current growth forecasts.

  • Phase 3
    As growth continues in the area, there is potential for a third phase in our long term plan to ensure reliability. The third phase would run approximately 1.9 miles along the Tolt utility corridor between 155th Ave NE and 132nd Ave NE. We will continue to monitor population growth, natural gas usage, as well as future planned residential and commercial development in the area over the next several decades to help us determine when the third phase is necessary for our customers. Current high-level planning estimates suggest this work would occur around 2033.

It's our goal to minimize construction impacts in the Tolt corridor, and for the people who utilize it, as much as possible. Our construction methodology was chosen to minimize impacts to the natural habitat and nearby wetlands, as well as to the corridor itself. After each stage of construction is complete, we will progressively restore the corridor back to its original condition.