The City of Prince Rupert needed to replace the Woodworth Dam on British Columbia’s Northwest coast and turned to Austin Engineering, now known as BBA, to optimize its redesign and help secure the project. This was a critical undertaking, as the 100-year-old infrastructure serves as a reservoir and water source for the community.

The aging dam and water supply lines needed to be replaced, and the city set about seeking funding and approval for an ambitious multi-year project to secure its primary freshwater source. Despite the success of the initial project stages, the challenges and costs associated with building a new dam in a remote region with limited road access threatened the project’s future.

The site was located seven kilometres from a tidal barge landing, which could only be accessed to load and unload equipment no more than three hours per day during high tide. All equipment, concrete, rock, aggregate and other items from the project needed to be delivered by barge to this landing and then trucked seven kilometres up a single lane forestry service road.

By undertaking a comprehensive value engineering review, our team members optimized the initial Woodworth Dam design and significantly decreased the project budget (by nearly 17%) using an innovative 3D printing approach. They also worked closely with First Nations to balance economic and environmental goals.

Our team’s goal was not only to reduce project costs to get the green light, but to work collaboratively in the interest of the environment and local communities. The best environmental and dam safety practices were put in place throughout the project to ensure its sustainability.

The completion of this state-of-the art freshwater distribution facility was celebrated in October 2022.

INNOVATIVE 3D PRINTING APPROACH 
When revising the initial design, our team compared several models using an innovative process: the dams were 3D printed, the riverbeds were CNC routed, and they were all tested in hydraulic flumes to confirm their flow characteristics.

This approach significantly reduced:
– Rock anchor quantity by 40%
– Concrete volume by 25%
– Rock excavation volume by 18%

It also helped provide environmental solutions:
– Re-using foundation rock saved 500 trips up and down the service road.
– Reducing rock excavation limited the amount of debris entering the stream.

Realistic model structures were used to communicate the new design to stakeholders in a visual and interactive way.

DAM SAFETY AND CLIMATE RESILIENCE 
Since Prince Rupert is known for its significantly heavy rainfalls, care was taken to predict and allow for future changes in flow regimes within the river system as a result of climate change. The spillway capacity was oversized to allow for future flood flows and demands.

CLOSE COLLABORATION WITH FIRST NATIONS 
As the project was located on First Nations land, these communities were involved throughout the project to ensure that special attention and care was taken to respect their culture. Also, the environmental consultant for the project was a First Nations joint venture partnership.

The City of Prince Rupert has been under a boil water advisory for a number of years due to turbidity in the water system that pumps from Shawatlan Lake. The project was accomplished with a substantial cost savings of nearly 17%, while balancing economic with environmental goals. Now, water can be taken directly from the Woodworth Reservoir and piped via HDPE pipeline down and across the harbour, entering the city’s water system. This is a major improvement in quality of life for the community!