Below the Surface: Engineering Innovation at new Surrey hospital and BC Cancer Centre

There’s more than meets the eye beneath the surface of a major EllisDon hospital build. Technical challenges often require projects to be built on foundations of innovation, collaboration, and problem solving – at the new Surrey hospital & BC Cancer Centre project (NSHBCCC), that foundation was more than a metaphor.

Located in an area with high seismic requirements and unique ground conditions, the team was tasked with delivering a hospital on demanding terrain. EllisDon’s Civil (Ground Engineering) department worked closely with subcontractors and partners at Fraser Health and Infrastructure BC to devise a foundation solution never before utilized in Canada – resulting in a novel system featuring a moat wall concept, diaphragm walls, a single‑shell permanent bathtub soil‑retention system, a specialized concrete mix design, and coordination, collaboration, and trust among all parties.

Hospital background

• A 1.1‑million‑square‑foot, state‑of‑the‑art hospital and cancer centre
• 168 patient rooms
• Advanced diagnostic services, including:
• Rooms for three CT scanners
• Rooms for three MRI machines
• Rooms for 6 radiation bunkers
• The BC Cancer Centre, specialized cancer care closer to home

Challenges

The site’s location in a high seismic area with soft clay soil and a high water head – including artesian water conditions – had historically limited building taller structures and deep basements in the region. Despite considerable geotechnical due diligence prior to construction, the team had to solve for significant water uplift pressure in the bottom till soil layer.

The site is also located in a high seismic zone governed by NBCC 2020, requiring elevated design forces for hospitals. As a post‑disaster facility, the foundation must withstand up to 40 per cent greater forces than a standard building, accounting for shaking, vibration, and movement during an earthquake.

Solutions and innovations

Culture of innovation cultivated through collaboration:

Like many of EllisDon’s other achievements, this one was largely built on strong relationships and proactive collaboration. This positive environment began with Early Contractor Involvement (ECI) during Tendering and Pre-Construction phases, which allowed all partners to be engaged throughout planning, design, and implementation. This meant:

• Early involvement across all parties:
  Consultants, sub-contractors, suppliers, and EllisDon’s lead team worked together early, allowing knowledge, experience, and responsibilities to be shared in real time.
• A well‑coordinated, trained, and prepared workforce:
  This collaborative approach resulted in crews ready to perform underground work safely, contributing to zero lost‑time incidents during foundation construction.
• Sustained high‑performance execution:
  Strong coordination enabled an unbroken 110‑day stretch of around‑the‑clock concrete pours, covering the full scope of diaphragm wall and barrette installation.

Moat Wall Concept

Challenge addressed: Water, soil pressure, and ground movement.

This design strategy implements an outer barrier to isolate the hospital from vibrations, seismic impacts, soil, and water pressure. Executed using diaphragm (slurry) walls, it became part of the permanent watertight bathtub system, providing high structural integrity, fewer joints, and saving space within the building’s footprint.

The system protects the structure from the surrounding environment and allows for a lighter inner structure that does not need to provide resistance. It also isolates the hospital from seismic impacts and vibrations from nearby railway tracks, enabling the foundation to stop water infiltration while reducing materials, cost, and schedule.

Barrettes Instead of Caissons or Piles

Challenge addressed: Heavy structural loads in a high‑seismic zone.

These large, rectangular deep foundation elements were selected because they are more stable and better equipped to manage heavy loads while accommodating earthquake stresses. To suit the high seismic location, the team developed a specialized concrete mix that remained at 50 MPa after 28 days of curing.

Because concrete continues to gain strength over time, exceeding 50 MPa would have made it too brittle during an earthquake. Keeping the concrete precisely at the required strength reduced the risk of cracking or failure under dynamic loads.

Raft Slab

Challenge addressed: Weight distribution and seismic uplift.

Once the barrettes were installed, a raft slab – a thick concrete floor – was constructed to spread the hospital’s weight evenly. The slab included post‑stressing with tiedowns to help resist upward forces during seismic events.

Non‑Curing, Self‑Healing Gel Membrane:

Challenge addressed: Groundwater pressure and long‑term waterproofing.

To protect against extreme groundwater infiltration, a non‑curing, self‑healing gel membrane was used. Unlike traditional waterproofing, it remains flexible and automatically seals minor damage, making it ideal for a site with high water pressure and numerous penetrations.

Its ease of installation and repair improved reliability, marking a first‑of‑its‑kind application for a hospital project in British Columbia. The poly‑rubber gel membrane also allowed the raft slab to be compressed by the diaphragm wall through strategic destressing of tiebacks, without the need for dowels or water stop bars.

In all, close collaboration between teams enabled a coherent, integrated foundation solution. The moat wall concept, watertight shoring, barrettes, raft slab, specialized concrete, and waterproofing work together to manage soil, water, heavy loads, and high seismic forces, resulting in schedule and cost efficiencies and an answer to the site’s harsh conditions.