Rainier Square, Seattle, WA (2021)

Shoring System: Temporary Anchored Soldier Piles and Anchored Secant Piles.

Client: Malcolm Drilling Company, Inc.

General Contractor: Wright Runstad & Company

Shoring Contractor: Malcolm Drilling Company, Inc.

Shoring Face Area: 84,000 Square Feet

Wall Depth Range: Up to 85 feet

Status: Completed 2021

The L-shaped development included a 58-story office and residential tower at the north end of the site and 12-story hotel at the south end. Underground parking consisted of 6-7 levels beneath the tower and 4 levels beneath the hotel. The development was constructed around the existing Rainier Tower office building occupying the southeast corner of the block. The Rainier Tower is supported on a shallow mat foundation that had to be supported by the shoring system. Anchored soldier pile shoring was used to support the excavation adjacent the City right-of-way and at interior grade changes. On the north side of the existing Rainier Tower, anchored secant piles were used to support the 45-foot deep excavation immediately adjacent the existing mat foundation. Because of limited right-of-way widths, up to 12 rows of anchors were employed. Deformations were restricted to less than 1-inch adjacent city streets and less than 0.5-inches adjacent the Rainier Tower.