The Terry Avenue condominium project in Seattle, Washington, was shored by the deepest soldier pile and lagging installation utilized in Seattle in 25 years. The owner-developer, Talieson Corporation of Vancouver, BC engaged Condon-Johnson & Associates (CJA) to assist with pre-construction design. The design was then performed by Skilling, Ward, Magnuson and Barkshire.

The Challenge
With the site only 125’ square, some of the soldier piles were longer than the site dimensions. The $ 2.2 million project had little or no lay down area for on-site fabrication, as the site was severely sloped.

The Solution
CJA arranged to have the Soldier Piles shipped in pieces and spliced in the vertical position. CJA constructed a cantilevered platform from uphill soldier piles, which provided room for grouting operations as well as tieback fabrication. At 114’ in depth, the Terry Avenue site was retained utilizing soldier piles to depths of 127’ and up to fourteen rows of tiebacks. Close cooperation was necessary between CJA working as the shoring contractor, and the excavating contractor, in order to efficiently place shoring while the excavation spoils were lifted by a three-stage belt conveyor.

The Result
Although plagued by numerous problems with hazardous soil and groundwater, the project was completed in seven months. The Terry Avenue development was profiled in Foundation Drilling Magazine May 2001.

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Soldier Pile & Lagging