This presentation draws from case study experience on Canada’s west coast to illustrate the benefits of a geomorphological design basis for development of climate-resilient nature-based shoreline solutions to address flooding and erosion hazards. Many of the beaches forming the shorelines of the Strait of Georgia and Puget Sound, in British Columbia’s lower mainland and neighbouring State of Washington respectively, and known collectively as the Salish Sea, are derived from sand and gravel eroded from nearby bluffs. The region’s glacial history and unique geology make these feeder bluffs an important source of beach sediment. The desire to stabilize coastal bluffs which are naturally subject to erosion to protect valuable upland assets can lead to long term sediment supply deficits and erosion issues on neighbouring shorelines. Understanding the relationships between coastal and feeder bluff slope processes, sediment transport and morphology is integral to avoiding conflict.

We will present several case studies illustrating how bluff and shoreline erosion hazards in the Strait of Georgia may be addressed with robust and climate-resilient nature-based solutions that consider coastal processes, sediment budget and geomorphological context.

Phil Osborne, Senior Coastal Geomorphologist, Golder Associates
Phil Osborne is a Principal with Golder Associates and senior practice leader for coastal engineering, oceanography and geomorphology services. Phil leads Golder’s global coastal and marine engineering technical community and provides strategic business and technical leadership for a wide range of services in offshore, coastal, and estuarine environments. He is subject matter expert in coastal dynamics, sediment transport, and geomorphology with more than 34 years of international postgraduate experience in research and consulting.

The Forillon National Park is located at the outer tip of the Gaspe Peninsula in Quebec and covers 244 km2. Created in 1970, Forillon was the first national park in Quebec. The park includes forests, seacoast, salt marshes, sand dunes, cliffs and the eastern end of the Appalachians. Parks Canada Agency has recently retained coastal and maritime expertise to develop engineering solutions to reduce access roads and infrastructures vulnerability to coastal submersion and erosion and enhance the long-term conservation value of the park.

The coastal infrastructures include access roads, recreational areas, parking lots, a fishing and recreational harbour and some key facilities to support the tourism industry. The damages and repeated maintenance works to these structures in the recent years are more frequent and costly for Parks. The preliminary studies were intended to develop engineering solutions to reduce the coastal vulnerability to the infrastructures, assess the impacts of the solution implementation on the coastal environment and customer experience and minimize the construction and maintenance costs. To meet these objectives, various coastal analyses to characterize and quantify the coastal hazards along the Forillon peninsula were undertaken and resilient technical solutions to preserve long-term operational services and conservation value in a context of climate change were developed.

The main activities undertaken to realize this project were:

• Hydrographic and topographic surveys;
• A condition assessment;
• Metocean data collection;
• Geotechnical field measurements including bore holes and stability analyses;
• Risk assessment of various infrastructures based on the development of setback lines for different horizons;
• Hydrodynamic and sediment transport modeling;
• Coastal engineering analyses to develop solutions adapted to site conditions and various stakeholder’s requirements, including the implementation of mitigation measures; and,
• Preliminary and detailed design, including site supervision during construction.

Nicolas Guillemette, National Manager, Coastal Engineering and Marine Works, WSP Canada
Nicolas Guillemette holds a bachelor’s degree in civil engineering and a master degree in environmental hydraulics, specializing in the fields of coastal engineering and marine works.

Nicolas has been involved in a diversity of high-profile projects as department manager and technical specialist for coastal engineering works with applications for shoreline protection, navigation, harbour and waterfront development as well as dredging and rehabilitation of a contaminated site. He realized a wide range of hydrotechnical projects as a technical specialist for the design of coastal structures, water quality of effluent discharges as well as coastal hazard risk assessments. He also has significant experience in coastal and ocean modelling and has undertaken numerous marine surveys and metocean studies.  

For many years Shippagan Gully has served as an important navigation channel, providing boaters from communities in the Acadian Peninsula in northern New Brunswick with direct access to the open waters of the Gulf of St-Lawrence. The fishing industry, a very important element of the local economy, relies on safe navigation through the inlet. Over the last few decades, significant volumes of sediment have accumulated within the inlet due to natural processes and deteriorated structures, rendering the Gully unsafe. The stabilization of the Gully was identified as priority by Department of Fisheries and Oceans, Small Craft Harbours Branch (DFO-SCH) in 2009.

The National Research Council of Canada (NRC) was contracted to study and model the channel and provide recommendations for the stabilization of Shippagan Gully.  NRC’s recommendations included several options to reduce the current, the level of infilling, and improve navigation and increase safety through the channel by improvements to/replacement of rusted out structures on the west shoreline (at the existing SCH facility); construction of new stabilization structures on the east bank; and dredging of the channel to -4.0 m (equating to >300,000m³ of infilled gravel, cobbles, sand).

The western shoreline stabilization included reconstruction/replacement of existing rusted-out structures and has been completed.   The remoteness of the east shoreline, environmental constraints, and unsafe navigability of the Gully, proved challenging for the completion of dredging and construction of training structures to the east.  The site is characterized as a sandspit comprised of critical habitat for the Endangered Piping Plover, fish habitat/eelgrass beds, wetlands, and dirt road/ATV trail access.

One of the main challenges of the project was to locate disposal site(s) for the dredge sediment.  Disposal at sea was eliminated early in the process due to the presence of marine habitat and fisheries resources in Gulf of St. Lawrence. Finding landbased disposal site(s) proved difficult in a surrounding environment with remote access and sensitive ecological features. The shallow and narrow channel, swift currents, exposure, high degree of coarse/granular materials, fishing season, and short weather window further complicated the design and implementation of the dredging component.

Public Works and Procurement Canada (PSPC), DFO-SCH and GEMTEC Limited eventually concluded that a phased approach to the east shoreline and dredging project would be most effective. The first phase would see the completion of a breakwater, shoreline stabilization, and ~66% of the dredging completed by land based equipment from the east shoreline.  A new 2.5 km road would be constructed (including a 400m causeway section) to allow site access for imported rock and exported dredged materials. The remaining ~33% of the dredging volume would be completed by floating equipment, protected by a breakwater and in a channel with sufficient draft to maneuver dredging equipment.

The environmental climate in this remote and sensitive area of construction was staggering.    The project approvals were coordinated through the Provincial EIA process, and sought input from various levels of stakeholders, regulators, and the Indigenous community for species at risk, fish habitat, wetlands, and archaeology/traditional use.