Esquimalt Graving Dock

Since 1990, KCB has provided design and construction engineering services to the Government of Canada for several projects at the Esquimalt Graving Dock near Victoria, BC. This graving dock, built in 1927, is the largest civilian dry dock on the west coast of the Americas. The Graving Dock includes several jetty structures which provide safe pre-docking moorage for ships, so that certain maintenance work and/or repairs can be carried out efficiently and more economically than in the dry dock itself. The facility also includes an open-water approach area within Esquimalt Harbour.

Challenges

  • Jetties for mooring ships outside the dry dock deteriorating
  • South and west timber jetties were built on relatively short timber piles and were likely to collapse in the event of a large earthquake
  • Risk of steel caisson gates failing during an earthquake, causing major inundation and possible loss of life
  • Open-water approaches and certain under-pier foreshore areas had contaminated seabed sediments, due to ship repairs and maintenance work

Solutions

  • Jetties slated for replacement or seismic retrofitting
  • KCB did a feasibility study for renewal of the south jetty, and subsequently analyzed and designed steel-piled replacement jetty structures
  • KCB evaluated seismic capacity and stability of caisson gates and performed field inspections and full engineering analyses to assess their static/seismic stability
  • Marine environmental remediation of under-pier sediments
  • Rehabilitation and removal or re-commissioning of the cranes, including two 30t cranes and a 150t crane

Successes

  • Our design team provided practical and efficient civil, marine, structural and geotechnical solutions for the wharf renewal program that satisfied the client’s operational needs through construction phasing of the works
  • Gates and sills were strengthened to resist earthquake loads associated with 475-yr and 1000-yr return periods, with a “no collapse” criterion at the 1000-yr level
  • Reducing high levels of contamination and controlling potential sources was performed under a multi-phase program, and supports the federal government’s environmental stewardship objectives

Paper:

Cross, R.A. and A. Port. 2015. “Geotechnical Seismic Assessment of a Pile Supported Wharf and Implications for Future Upgrades,” in Proceedings of the 11th Canadian Conference on Earthquake Engineering (11CCEE), Canadian Association of Earthquake Engineering, July 22-24, Victoria, BC.