Britannia Creek Debris Flood Mitigation

Project Highlights

Working on behalf of the developers, for over two decades KWL has been leading a team of consultants to assess and mitigate flood-related hazards for the redevelopment of the historic Beach community.  This highly complex project has included landslide and landslide dam outburst debris flood assessment by BGC Engineering, river and coastal flood hazard assessment by KWL, and preparation of a comprehensive debris flood mitigation plan by KWL.  As part of the mitigation plan, a Geobrugg flexible ring net debris barrier has been installed on Britannia Creek.  Input was provided to the Province’s dam deconstruction program, resulting in the deconstruction of multiple dams and retention of Tunnel Dam as an informal debris barrier.  On the creek fan, the development area was raised on a structural fill platform, protected around the perimeter by heavy rock riprap.  Residential buildings on the platform additionally have raised concrete perimeter foundations to further reduce the potential for structural damage during an extreme creek event.  The Squamish-Lillooet Regional District (SLRD) has accepted responsibility for the flood protection works, and an advanced operation and maintenance manual has been prepared for this purpose.  A project-specific system for building approval has been developed in coordination with SLRD, including an engineering report within a restrictive covenant, flood and landslide assurance statements, a certification of flood safety, an implementation plan for site grading and flood protection measures, and a flood protection checklist for each building.  This has resulted in submission of building permit applications for the project, and recently occupancy approval for some completed buildings. KWL continues to oversee implementation of the plan through construction monitoring such that occupancy of the final buildings can be achieved.