The Trans Mountain Expansion Project (TMEP) is one of the largest and most complex pipeline infrastructure projects ever undertaken in Canada, with a capital cost of more than $34.2 billion. The Westridge Marine Terminal (WMT) in Burrard Inlet represents the western terminus of the system, connecting the newly twinned pipeline system to tanker vessels for crude oil export to global destinations. The newly expanded WMT comprises of three new vessel loading berths and significantly increases the oil export capacity from the Westridge terminal, replacing the original 1950’s era single berth which had operated at the site for almost 70 years. Each berth is capable of accommodating vessels ranging in size from barges to Aframax tankers that can range to about 125,000 deadweight tonnes (DWT). The completed project resulted in one of the largest-ever step-increases in exports through the Port of Vancouver. After more than four years of construction, the TMEP was completed, and the first tanker was loaded with export oil transported on the new pipeline on 20th of May, 2024. The project required installation of some of the longest and largest steel pipe piles ever used in a maritime project in British Columbia (up to 2.3m in diameter and 73m long). A complex construction sequence had to be designed to allow for construction of the new facilities without interrupting ongoing operations of the immediately adjacent original berth. An EPC procurement model allowed the engineering team to work closely with the contractor much like a design-build project, optimizing the engineering design to best suit the contactor’s preferred means and methods of construction. Moffatt & Nichol (M&N) was retained by Trans Mountain Pipeline (TMP) to carry out the preliminary design, detailed engineering, and construction engineering support services for the three new WMT berths, as well as a new Utility Boat Berth to accommodate tugboats, spill response craft, and other small utility vessels.

The deep layers of soft marine clays added significant challenge to the project design and construction. To better understand and mitigate the potential amplification of seismic ground motions through the marine clays, an advanced multi-level performance-based seismic analysis was required, first using a conventional Response Spectrum Analysis to define overall global system response, followed by a more detailed Nonlinear Time History Analysis. The three berths were integrated into a single continuous structure with no isolation or expansion joints in the deck structures. This approach effectively tied the various portions of the structure together, dramatically reducing differential out-of-phase seismic movements which in turn significantly reduced induced stresses in the product piping. Working closely with Trans Mountain’s selected marine construction contractor, Kiewit Ledcor TMEP Partnership (KLTP), the M&N team developed a structural solution using all-vertical steel piles. As part of a value engineering exercise, M&N worked with KLTP to develop a unique “double decker” jetty layout where some of the mooring dolphin structures were placed beneath (and structurally isolated from) the trestle deck above. This approach eliminated three mooring dolphins, saving millions of dollars in capital cost, months of construction time and significantly reduced the project environmental footprint as well as construction impacts on the surrounding community.

The Westridge Marine Terminal is one of the largest and most technically challenging maritime infrastructure projects ever completed in BC history. The equipment used to deliver the project and install the facility included the largest heavy lift marine derrick barge on the west coast of North America. Advanced performance-based seismic engineering combined with an innovative layout and design led to a practical berth facility that will serve Trans Mountain’s needs for decades to come.