Rehabilitation of the largest civilian dry dock on the west coast of the Americas
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. It also has several jetties for mooring ships outside the dry dock, which were deteriorating and are slated for replacement or seismic retrofitting.
Our work at the graving dock has included:
- a master plan for the development and future use of the graving dock facilities;
- seismic evaluation of the dock walls and the south jetty structures;
- a 30m long extension of the graving dock;
- rehabilitation and subsequent removal of the 45t hammerhead crane;
- rehabilitation and re-commissioning of the 150t crane after luff drive failure;
- structural fatigue upgrade of the 150t level-luffing crane;
- rehabilitation and relocation of the 30t EBCO crane;
- installation and commissioning of the 30t Kone crane;
- seismic evaluation and structural retrofit of caisson gates and sills;
- evaluation of structural condition and stability of timber cribs;
- multiple assignments for dock facility upgrades and to improve safety; and
- marine environmental remediation of under-pier sediments.
Fatigue Analysis and Structural Retrofit
In the early 2000s, KCB performed fatigue analysis and retrofit design of the 45 tonne hammerhead crane and the 150 tonne level-luffing crane. Both cranes are rail-mounted and support dry dock operations. We determined the feasibility and viability of necessary structural retrofits, and carried the retrofit designs through to construction completion. KCB was the prime consultant for the project, with technical roles involving structural and mechanical engineering. Our team also developed a fatigue monitoring program to allow for continued performance of the retrofitted cranes, based on the client’s operational needs.
South Jetty Wharf Redevelopment
Esquimalt 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 south and west timber jetties were built on relatively short timber piles and were likely to collapse under the design-level earthquake event. KCB initially carried out a feasibility study for renewal of the south jetty, and subsequently analyzed and designed steel-piled replacement jetty structures, including seismic compatibility / connectivity with adjacent wharf structures that were to be left in place, modification and upgrade of mechanical and electrical utility services, and our team examined all key operational and constructability issues. 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.
Seismic Evaluation of Caisson Gates & Sills
KCB evaluated the seismic capacity and stability of the two steel caisson gates. If a caisson gate, or one of the supporting dock sills, were to fail during an earthquake, major inundation would result along with possible loss of life in the graving dock. We performed field inspections and full engineering analyses to assess the static/seismic stability of these cellular steel structures and their concrete berthing sills, and then proceeded to final design and construction inspection. The 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.
Marine Environmental Remediation
The Esquimalt Graving Dock facility also includes an open-water approach area within Esquimalt Harbour. The open-water approaches and certain under-pier foreshore areas are known to have contaminated seabed sediments, due to the nature of the ship repairs and maintenance work carried out in prior years. Environmental due diligence and liability risk reduction was made under the Federal Contaminated Sites Action Plan (FCSAP), based on levels of contamination present and the potential for contaminant migration to other parts of the harbour. Reducing high levels of contamination and controlling these potential sources was performed under a multi-phase program, and supports the federal government’s environmental stewardship objectives.