The decision is subject to Enbridge Energy LP securing additional government approvals and permits and conditions related to the tunnel’s safety and construction.
The Commission found there was a public need for the replacement section of Line 5 and the light crude oil and natural gas liquids it carries, and that without the pipeline, suppliers would need to use higher-risk and costlier fuel supply sources and transport.
The order also recognised there was a public need to protect the Great Lakes’ environmental and culture resources that would be helped by replacing the existing dual pipelines, now exposed to the elements and to risks including ship anchor strikes on the lakebed. Other modes of transporting Line 5’s products, such as truck, rail, oil tanker or barges, were likely to increase environmental damage and increase the risk of spills.
The Commission also found that:
- Enbridge has demonstrated that an experienced and knowledgeable firm designed the tunnel, and it will be built using state-of-the-art materials and practices that will meet or exceed industry standards.
- The replacement segment is a significant improvement over the existing dual pipeline configuration, virtually eliminating the risk of anchor strikes, in addition to the replacement segment being housed in a tunnel that can serve as a secondary containment vessel that would contain a leak if one developed.
- The Straits Line 5 replacement segment meets or exceeds current safety and engineering standards, given that the inspection procedures required by Enbridge for manufacturing and installation exceed required minimum safety standards.
The Commission also found that the route, location, and design of the project was reasonable and should be approved, subject to conditions. These include exceeding minimum federal regulations to ensure the safety, integrity and reliability of the Straits Line 5 replacement segment. The Commission directed Enbridge to implement procedures for low-hydrogen welding for all mainline girth welds and to ensure that the procedures require both preheat and inter-pass temperature requirements. Enbridge must also ensure that the mainline girth welds are non-destructively tested using automatic phased array ultrasonic testing methods.
The Commission also required that before Enbridge begins construction it submits a detailed risk management plan that includes geotechnical test bore sitings with related data and real-time reporting; results of concrete cast section inspections; placement plan of gaskets; analyses of bentonite mix, and any changes in slurry pressure.
The Commission also recommended that all equipment used in the tunnel should be designed to meet the most stringent standards for electrical equipment under the National Electric Code.
First built in 1953, Line 5 is a 1,038km (645-mile) interstate pipeline from Superior, Wisconsin, across Michigan’s Upper Peninsula, the Straits and the Lower Peninsula before terminating near Sarnia, Ontario. Its average annual capacity is 540,000 barrels per day.
In the approximately 6.4km of Line 5 crossing the Straits, there are currently two, 508mm (20in) pipelines, the span of which are primarily near or on top of the lakebed. Enbridge would replace the dual pipelines with a single, 76mm (30in) pipeline in the concrete-lined tunnel with an inside diameter of 6.4m (21ft), routed through bedrock 18-113m (60-370ft) beneath the lakebed. The tunnel will have space for the Line 5 replacement segment in addition to ventilation systems, leak detectors, dewatering equipment, and equipment needed for inspections and maintenance.
Enbridge initially filed its application in April 2020 and in July last year the Commission asked Enbridge to file documents and any relevant information to develop a full record on tunnel engineering and safety, electrical equipment and risk of fire and/or explosion, and the safety of the current dual pipelines, including leak detection systems and shutdown procedures.
