Under the Sea
Challenges and Opportunities in Marine Construction
Marine construction – a combination of harsh environment and special considerations. North America has plenty of coastline and the demand for construction in the marine environment isn’t going away any time soon. Yet we don’t often consider or even think about what goes into the design and construction of the structures that bridge our waterways, line our shores and allow the docking of our largest cargo ships.
I recently had the pleasure of interviewing an engineer who specializes in exactly this sort of construction. Kasey Gignac, P. Eng, didn’t initially set out to be a structural engineer who specializes in marine construction but, she shares, “I always knew I wanted to be an engineer. Getting into the marine construction sector was a complete fluke that happened by chance.”
Ms. Gignac was a junior engineer working for CBCL Limited, an engineering consulting firm based in Atlantic Canada, who was just lucky enough to be paired with senior engineer Greg Peters to work on the marine construction projects CBCL was undertaking at the time. Ms. Gignac is a native of Nova Scotia and attended Dalhousie University in Halifax where she obtained her B Eng. in Civil Engineering. She credits her parents for fostering her interest in construction and science at an early age, saying, “I was always drawn to books of house plans and interested in construction, I knew from a young age that I wanted to be an engineer.”
Ms. Gignac currently works at New Brunswick Community College (NBCC) in the Building Engineering Technology program in Moncton, where she serves as head instructor for the Structural Engineering Technology program. Her role at NBCC has allowed her to marry two of her passions: engineering and teaching. It was difficult for her to leave the consulting field, but the opportunity to teach in her field was one that she simply couldn’t turn down.
When asked about some of the unique and special considerations of the marine engineering and construction fields, Ms. Gignac explained that, “The very harsh environment, ice floes, tidal ranges, rising sea levels and working over water all make for challenging design and work conditions which make the marine construction field unique.” Additionally, everything about the marine construction sector is big – from the forces applied to structures, to the vessels and equipment that dock at or operate on wharves, to the structures themselves.
We can’t typically see the sheer size of marine structures as they often spend their entire lifecycle partially or primarily submerged beneath the waves of our waterways and oceans. While structures fundamentally behave the same whether built on land or in water, the specialized knowledge required to design and build structures for the marine environment is quite unique in the construction world. “Coming out of school as a civil engineer, I had to learn about marine lingo and familiarize myself with things like berthing procedures, bulbous bows, fore and aft and a whole lexicon of unique and specialized terminology that’s not found anywhere else in the design world,” Ms. Gignac explained. Her understanding of vessels is something she had to learn as she went along in order to succeed as a structural engineer in the marine sector.
To be sure, the challenges presented by marine construction are different than with structures on land. The unknowns present in a marine setting are unique. Geotechnical assessments – that is, the assessment of the earth below ground for the purposes of foundations for structures – are much more difficult when they have to be done many metres under water and it’s a lot tougher to be certain of the depth of bedrock, for example. Other factors, such as occupancy and loading, can be much more difficult to predict on a marine structure compared to a typical building. Large ships, shipping containers, cranes, and similar make designing for live loads much more challenging to a designer of a marine structure.
Ms. Gignac also pointed out that, while not entirely unique to marine construction, building over, around and right next to existing structures is very common in the field. Often, it’s impossible to fully remove an existing marine structure or to perform a full pile extraction as this might affect slope stability and the integrity of back land infrastructure. Finally, another distinct challenge for marine designers, at least in Canada, is the lack of a uniform design code for marine structures (like the National Building Code of Canada). At present, Canadian designers and engineers often have to combine or interpret codes from the U.S. (Unified Facilities Criteria, for example) and the U.K.
With all the unique challenges and differences present in marine design, Ms. Gignac is particularly proud of her work on the expansion of the Irving Oil Terminal in Saint John’s, Newfoundland, one of her last and largest projects while employed at CBCL. The terminal expansion was a major project for CBCL that involved the design of a reinforced concrete piled wharf, engineered fendering system and slope stability and protection to serve as a marine gas oil (MGO) terminal (a refuelling station for vessels) in the Saint John’s harbour. CBCL provided design and services during construction for the terminal project which also included all of the back land services (municipal services) for the project – elements like road access to the wharf, drainage, security fencing and all other amenities required for the operation and maintenance of the terminal. This also included all of the piping infrastructure necessary to get the MGO product to the terminal so it can be used in the refuelling of vessels. The design had to be flexible as well; the terminal needed to be built in such a manner as to allow for future development and expandability.
One of the interesting design elements of this particular project was the use of what’s called a combi wall, or combination wall. A combi wall is a combination of sheet piles and circular piles driven into the ground which act as a retaining wall to aid, in this case, in slope stability of the site. Slope stability was of concern for the design of the terminal and so the decision was made to use the combi wall, something that isn’t terribly common. Ms. Gignac lamented jokingly that, “Everything that’s time consuming, interesting, challenging and fun about marine design never gets seen.” In this case it was the combi wall – vitally important and, like much of what engineers design, out of sight.
Ms. Gignac is confident that the marine construction industry as a whole is growing and will always be of importance, particularly in her region; they call them the Maritime provinces for a reason after all. One unfortunate trend she’s observed is the low representation of women in the field of engineering as a whole; presently, women comprise less than 13 percent of professional engineers in Canada, according to Engineers Canada. Helping to combat this trend is the initiative 30 by 30 (see sidebar for more details) which aims to see this number rise to 30 percent by the year 2030. Ms. Gignac has been involved with the 30 by 30 initiative for several years now and acts as a mentor to young girls, even helping young Girl Guides obtain their engineering crest.
Certainly, the marine construction and design fields are unique in the engineering and construction world, and the need for individuals with the specialized knowledge, skill set and experience to work in this field won’t be going away any time soon. According to the World Resource Institute, Canada and The United States combined have approximately 399 000 kilometres of coastline, representing a tremendous amount of potential for marine construction and development. There will always be a need for the construction and remediation of marine structures along our shores.