Matthew Blackwell, Goldspring Ha, Jenna Lozano, Gabriel Pollitt, Stefane Prairie and Julius Yagihara
- Community Partner: Danish Hydraulic Institute
- Degree:
- Bachelor of Applied Science
- Program:
- Campus: Vancouver
Our project
The impacts of climate change and the increased frequency of significant winds and wave action have resulted in ongoing damage to certain sections of Vancouver’s Stanley Park Seawall, requiring costly maintenance as well as safety risks. We redesigned a critical 1.1-kilometre section of the wall between Second Beach and Third Beach where there is significant evidence of erosion, undermining and scouring.
With the sea level expected to rise by one metre by 2100, our goal was to create a high-performing, long-lasting solution that could ensure climate resiliency well into the future.
We also wanted a design solution that was aesthetically pleasing and maintains the historical value of the existing seawall façade.
Our design solution
Our design consists of four main components:
- Submerged rubble mound breakwaters to dissipate wave energy before the waves reach the wall.
- A retrofit of the existing seawall – including building a concrete retaining wall on the landward side – to raise the height of the seawall by 1.5 metres while maintaining its historic appearance.
- Intertidal habitat incorporating nutrient-rich sediment, gravel and stones of various sizes collected from Third Beach to support the recovery of native vegetation and marine life.
- A revetment built from armouring stone that matches the armour layer of the breakwater, built up to 1.5 metres from the toe of the existing seawall that helps with erosion and undermining at the base of the wall.
The technical challenges we faced
Coastal engineering was new for many of us. This meant that we spent much of our first term broadening our knowledge base in this field. We also needed to consider very specific site challenges when developing our construction plan. This is a logistically complex site, with water on one side and a cliff on the other.
Under federal regulations, we could only schedule the construction over a few months of the year, and there are further complexities with needing to account for different tide levels from day to day. We’ve brought in mini excavators and barges to carry out the construction in a way that minimizes impacts on both the environment and on park users.
Another challenge was the limited data on the current strengths of the seawall. The wall was built from 1917 onwards, and we simply did not have the detailed information needed to calculate how much weight the masonry can bear. To retain the historical significance of the seawall, we decided to build a wall behind it that can handle the hydrological pressures the soil gains when it is full of water. With this solution, the current wall doesn’t have to resist any additional loads and can keep its historical nature and significance.
This project also required us to balance competing criteria. When you are on the seawall looking out to the horizon, you don’t want to be looking out at a massive breakwater structure, even if it’s more effective from a technical standpoint. So we decided to submerge the breakwaters.
In the first decades, the breakwaters might look large because we need to design for one-metre sea level rise. As time goes on, these breakwaters will be more hidden. This balances the need to reduce wave height while also maintaining the experience of walking along the seawall.
What we’re most proud of
This was a new technical area for some of us, yet we were able to deliver a design solution that meets the complex needs of the location.
Our work on the intertidal zone has created new habitat to address the existing shoreline of bare bedrock. We developed a sediment and vegetation plan to turn the area between the bedrock and the new wall into a space that can support plants, mussels and clams. Nature-based engineering solutions within these kinds of high-energy environments are still relatively new, so there wasn’t a lot of prior research we could draw on.
Finally, we’re proud of how our team worked collaboratively. The project had a lot of large, interdependent deliverables and it was very rewarding to see everything come together.
