Nautical Landing Abutment Stabilization

Nautical Landing Marina | Seattle, WA

  • Client
  • Nautical Landing Marina
  • Location
  • Seattle, WA

Project Overview

In 2013, the owner of Nautical Landing marina hired OAC to act as structural engineer of record for the stabilization of an undermined concrete abutment supporting a heavy timber dock on the property. The dock structure is required to serve 30 ton fuel trucks for large yachts on a regular basis. It had been recently discovered that the abutment supporting the west end of the dock was bearing on loose, sloughing shoreline soils.

OAC was hired to devise a retrofit scheme that would underpin the existing abutment with minimal impact to the surrounding shoreline and shoreline structures at this property. One issue complicating the project was that the abutment was found to bear on land owned solely by the Seattle Department of Transportation (SDOT). Throughout the project, it was important for our structural engineers to communicate clearly and effectively with engineers at SDOT.

OAC started with a visual assessment of the abutment structure from below. Record drawings were obtained, but contained little information on the existing reinforcing layout for the abutment. Non-destructive testing (NDT) was carried out by the owner on our recommendation, such that exiting abutment reinforcing presence and general layout could be determined.

OAC performed structural analyses of the abutment and various retrofit options involving driven steel pipe piles with custom steel brackets with input from the owner’s geotechnical engineer and piling contractor. Following the selection of the most cost-effective retrofit option, OAC produced permit drawings and calculations, and stayed on to conduct structural observation during construction as mandated by SDOT.

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