Seattle Department of Transportation

N Northlake Way Wall Replacement Alternatives Evaluation

SG3 was engaged as the Utility Coordination Lead for an evaluation of the replacement of an existing public retaining wall on the north shore of Lake Union. Ongoing inspections and observations of the 432-foot timber soldier pile wall with tie-back anchors and an exposed wall height ranging from 7 to 15 feet, indicated that several existing timber piles are deteriorating, and the wall is actively moving. SG3 developed the utility relocation plan component of the evaluation, to provide safe and effective working space for demolition of the existing wall and construction of the new structure. Utility services to adjacent water-side properties must be maintained, requiring a temporary service plan. After wall construction, all utilities are to be installed in permanent restored locations to continue serving utility customers.