Simultaneously erecting the 69-story Stantec Tower—western Canada’s tallest—and the adjacent 56-story JW Marriott required “cohesive teamwork” to overcome numerous technical and coordination challenges, according to construction manager PCL Construction, which managed the overall project and its four different design teams who worked from offices spread across North America. Additionally, the project’s supply chain spanned the globe, with materials procured from Vietnam, India, Italy, Spain, Brazil and China.

Challenges related to the Stantec Tower began during the design stage, says Terrance Wong, Stantec principal and architect of record. During schematic design, an early geotechnical report on soil conditions at the site—where an existing structure had previously stood—caused designers to reduce the tower’s ultimate height and switch to a foundation system of 1.8-m-dia. caissons drilled as much as 80 m into the ground. Another challenge involved construction of a 2-m-deep, 2,200-cu-m concrete transfer slab on the 30th floor, where the tower’s floor plate reduced with the transition from office space to residential.

The JW Marriott tower required a concrete mix with both a high modulus of elasticity to meet wind-acceleration requirements, and the ability to reach strength requirements quickly to accommodate form stripping. When the project team discovered that local materials produced extremely low modulus numbers, PCL worked with the concrete supplier’s R&D unit in France to develop a first-of-its-kind aggregate mixture design to achieve the desired strength and specified modulus of elasticity. Despite the hurdles, contractors completed the record-breaking project in just over three years.

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