Tunnel Condition Assessment and Remediation – Wreck Cove Generating Station

Wreck Cove Tunnel was constructed in the 1970s in Cape Breton, Nova Scotia, to convey water from the McMillan reservoir to Surge Lake, the head pond of the hydro generating station. As a crucial piece of providing clean, renewable energy, a hydro system like Wreck Cove requires upgrading to continue operating. Nova Scotia Power engaged us to assess Tunnel T-1 and Tunnel T-2—aging, unlined water conveyance tunnels excavated in rock.

Using a remote operated vehicle (ROV), we completed a condition assessment of the two tunnels. Collecting geotechnical data to support the design and construction of remedial measures, we conducted two drilling investigations—comprising nine geotechnical boreholes, detailed core logging, and televiewer surveys and hydraulic conductivity testing. Our team developed and evaluated options for the remediation of a collapsed section within Tunnel T-2, and we performed stability and hydraulic analyses and the conceptional design for remedial options, such as a bypass tunnel.

As a result of our intensive assessments, we provided cost estimates for remedial options. We also prepared technical specifications and drawings for the tender phase of the project to help Nova Scotia Power take the next steps.