Four106, Bellevue, WA (2023)

Shoring System: Temporary Anchored Soldier Piles

Client: Fana Four 106 LLC

General Contractor: M. A. Mortenson Company

Shoring Contractor: Malcolm Drilling Company Inc.

Shoring Face Area: 63,810 Square Feet

Wall Depth Range: 75 to 90 feet

Status: Completed 2023

The development included a 21-story office tower and eight levels of below-grade parking. Because of the overall excavated depth, and presence of water-bearing sandy soil conditions near the bottom, soil nailing was considered too risky, and so a conventional anchored soldier system was utilized. However, there were unique deep utility and basement challenges on three sides, as well as limited easement widths along the highest walls on the north and west which resulted in relatively heavy beams for cantilevering upper wall areas, and steep anchors closely spaced in upper rows to stay within the easement widths and meet the performance needs of the project. Wall movements were less than 1 inch on the street sides, and less than ¼ of an inch on the south where the existing Soma Towers condominiums were located within a few feet of the excavation face.