Foundations for TL Upgrade

Puget Sound Energy’s Sammamish-Juanita 115 kV project provided a critical upgrade to increase system capacity and reliability in the Redmond and Kirkland, WA areas. It consisted of adding just over five miles of new and upgraded 115 kV transmission line, upgrading aging substation equipment, and looping in the Totem substation.

Team Members

Puget Sound Energy


Crux Subsurface

Crux’s Role

Crux was selected to complete 28 direct embedded pole holes, 46 vibratory casings, 12 drilled pier foundations, eight 24-inch plate anchors, and a unique monopole foundation consisting of six grouted helical piers tied together with a steel cap. Direct embedded pole holes ranged in diameter from 3 to 4 feet and in depth from 8 to 20 feet. Drilled pier foundations ranged from 6 to 8 feet in diameter and from 33 to 42 feet deep; several required wet hole methods. Helical piers were drilled to 50-foot depths.

Highlights included successfully navigating underground utilities at more than 35% of the structure locations, which required crews to pivot from originally planned means and methods during construction. Additional challenges included navigating narrow access roads with heavy foot traffic and working within the congestion of Kirkland city limits. Permitting issues for traffic control substantially affected working hours and necessitated night shifts to complete foundation work within the schedule.

28 direct embedded pole holes, 46 vibratory casings, 12 drilled piers, eight plate anchors, and a unique grouted helical foundation.

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