Topcliff Avenue erosion control and slop stabilization

SLR was retained by the client to develop conceptual and detailed designs for channel improvements and erosion mitigation in a residential area affected by decades of urban development.

Challenge

Since the 1960s, urban expansion in the area had led to uncontrolled stormwater runoff and increased peak flows, exceeding the channel’s natural capacity. Ongoing erosion and planform changes had undermined valley wall stability, with runoff from Topcliff Avenue accelerating gully formation and valley degradation.

The project aimed to reduce risk to private properties along Topcliff Avenue by stabilizing the channel and valley slopes, while preserving natural fluvial processes and enhancing local ecological functions.

Solution

SLR led the design of a 200 m channel realignment and valley wall slope stabilization with the primary goal of reducing erosion-related risks to private properties along Topcliff Avenue.

Following completion of the design drawing package, our team worked closely with the contractor as part of a design-build partnership and provided engineering support during construction of the works.

• In Reach 1, the ultimate design included a 200 m channel realignment to shift the stream away from the valley wall and nearby private properties at the top of slope.
• In Reach 2, valley slope stabilization was accomplished through the installation of a mechanically stabilized earth (MSE) retaining wall structure.
• Features included a meandering riffle-pool channel design and grade control structures to manage flow energy, along with bioengineered bank protection to stabilize the realigned channel and establish a healthy riparian corridor.

Topcliff Avenue before and after

Impact

• SLR leveraged a multidisciplinary team of experts in geomorphology, hydrology, aquatic and terrestrial ecology, water resources and geotechnical engineering, environmental permitting, and construction oversight.
• Delivered a detailed channel design aligned with the client’s objectives for erosion mitigation, slope stability, and ecological enhancement.
• The client monitored site progress and published project updates.
• The project was successfully completed to the client’s satisfaction.