Canadian Pacific Kansas City (CPKC) engaged Ausenco to design a compensation habitat in the Burrard Inlet to create an artificial underwater reef and augment it with kelp reforestation.
Offsetting habitats are incorporated to compensate for environmental impacts during development projects. By integrating nature-based solutions, coastal engineers design infrastructure that not only protects against erosion and flooding but also enhances biodiversity and ecosystems.
One example is kelp reforestation, a marine forest that provides a habitat for a wide range of marine organisms and maintains ecological balance and resilience. The long-term reforestation of kelp beds can help to offset carbon emissions and potentially reduce the severity of effects created by climate change.
The challenge
Recognizing the importance of kelp in the area, our client contracted Ausenco to design an artificial reef to mitigate construction impacts of their terminal expansion.
Our coastal engineers and marine biologists worked together to define the best location, elevation and substrates to create a stable and ecologically efficient habitat. Our team looked for areas with a deep rocky reef, a subtidal bench, a shallow rocky reef, an edge habitat and an enhanced intertidal sandflat.
The better way
To design an artificial underwater reef, our team evaluated the required rocks that would be stable in the face of local waves and currents and their correct elevation. Key was determining the right location that allowed for the reefs to be submerged or above water for optimal times during the tidal cycle and had the correct substrate and sediments to create a healthy habitat.
The main components of the designed habitat were:
- A deep rocky reef: The most offshore component of the project, this reef is composed of large rocks and used to provide protection and stability. Our dive team deployed the kelp onto fabricated anchors and lines and strategically placed the kelp around the reef.
- A subtidal bench: Our team created a bench comprised of a sand, gravel and cobble mixture, located between the deep and shallow rocky reefs.
- A shallow rocky reef: We created a shallow reef composed of large rocks located onshore of the subtidal bench.
- Edge habitat and the enhanced intertidal sandflat: This feature is in the intertidal zone, with different mixtures of sand, gravel and cobble. We included piles of large boulders to give a more natural look to the beach and oyster shells to provide shelter and a source of calcium for small invertebrates.
Outcomes and achievements
This multi-faced compensation habitat is the first of its kind in Burrard Inlet. Designed by Ausenco's coastal engineers and marine biologists, the construction of the habitat was finished in December 2024.
Initial post-construction surveys indicated that the habitat is being colonized, and the kelp reforestation is healthy, creating a fully functioning habitat and providing juvenile salmon with shelter and food as they grow and migrate.
