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Enbridge Energy’s Line 5 pipeline was built in 1953 and extends for 645 miles across the state of Michigan. Line 5, which is part of Enbridge’s Lakehead System, begins in Superior, Wisconsin, and ends in Sarnia, Canada.

Line 5 details

The pipeline is a single, 30-in diameter pipe except for the section that crosses the Straits of Mackinac. That 4.5-mile section is two separate pipelines, each 20 inches in diameter, that lie on the lake bottom. The pipeline’s route through the Straits is within an easement issued in 1953 by the State of Michigan. The easement authorized Lakehead Pipe Line Co., Inc., which eventually became Enbridge Energy Limited Partnership, “to construct, lay and maintain pipe lines over, through, under and upon certain lake bottom lands …for the purpose of transporting petroleum and other products. … ”

Line 5 transports up to 540,000 barrels – or 22.68 million gallons – per day of light crude oil and natural gas liquids, according to Enbridge. Some of the natural gas liquids are refined into propane and used in the Upper Peninsula, while other products are routed for processing at oil refineries in Detroit and Toledo, Ohio. The remainder crosses the St. Clair river for processing in Sarnia.

Some Michigan drilling companies use Line 5 to transport the oil they produce. That product is introduced into the pipeline at Lewiston, Michigan.

Marshall spill raises awareness

In 2010, about 21,000 barrels of heavy crude oil spilled in a tributary of the Kalamazoo River near Marshall from a line owned by Enbridge.

As a result of the Kalamazoo River spill – one of the largest inland spills in U.S. history – the State and Enbridge in May 2015 entered into a $75 million Consent Judgment. That was followed in July 2016 with a Consent Decree between Enbridge and the federal government to resolve claims related to the Marshall spill. Enbridge agreed to pay $110 million on spill prevention and pipeline operations in the Great Lakes region and a $61 million fine. Cleanup efforts are ongoing and are estimated at more than $1 billion.

The spill prompted increased attention and focus on the potential ecological and economic damage that could occur if the Line 5 pipeline running beneath the Straits of Mackinac failed.

State creates pipeline task force

The Marshall pipeline spill led to the creation of the Michigan Petroleum Pipeline Task Force with the mandate to take a closer look at pipelines transporting petroleum products around the state, and specifically Line 5.

One recommendation in the Task Force’s final report was to create the Pipeline Safety Advisory Board (PSAB), which would review and recommend actions for the state to ensure the safety, upkeep and transparency of issues related to the network of more than 3,400 miles of petroleum and hazardous liquid pipelines in Michigan. It also was charged with advising state agencies on matters related to pipeline routing, construction, operation, and maintenance, and with helping Michigan to better understand the risks, benefits, and alternatives to pipelines.

Board initiates Line 5 analyses

The Pipeline Safety Advisory Board oversaw two independent analyses of Line 5, which the Task Force recommended: An alternatives analysis that was to look at the feasibility of other forms of transportation to handle the same amount of product that moves through Line 5, and a risk analysis of the potential financial impact of a worst-case spill to determine the final assurance amount as required under the 1953 easement. The alternatives report was submitted in June 2017 while the risk analysis was completed in August 2018.

Coating gaps, anchor strike

In between, Enbridge alerted the state to gaps in the protective coating on the pipeline in the Straits, information the company had as early as 2014. The information was revealed as part of Enbridge’s permit application to the Department of Environmental Quality (now known as the Department of Environment, Great Lakes, and Energy, or EGLE) to install additional anchor screws to secure portions of the pipeline to the lakebed in the Straits.

In April 2018, Line 5 in the Straits was damaged by a boat anchor that was dragged along the lake bottom. The anchor caused three dents to the pipeline – two on the western segment and one on the eastern segment – and raised concerns about the vulnerability of the pipeline to other anchor strikes. The strike led to the State of Michigan declaring a portion of the Straits a “No Anchor” zone and the subsequent approval by the United States Coast Guard of a regulated navigation area in the Straits where boats and ships can only under certain circumstances or during an emergency drop their anchor.

First agreement between Enbridge, State

In November 2017, the State of Michigan announced an agreement with Enbridge, known as the First Agreement, to compel the company to add protections for the Straits of Mackinac and the Great Lakes. The agreement called for Enbridge to fix gaps in Line 5’s protective coating and undertake a study of three alternatives to replace the pipelines in the Straits: a tunnel, horizontal directional drilling or a trench with secondary containment.

The First Agreement also called for Enbridge to replace the portion of Line 5 that crosses beneath the St. Clair River with horizontal directional drilling, temporarily shut down Line 5 during periods of sustained adverse weather conditions in the Straits, implement additional underwater technologies to better monitor the pipeline beneath the Straits, implement measures to mitigate a potential vessel anchor strike, evaluate every Line 5 water crossing in Michigan and implement measures to minimize the likelihood of an oil spill at these locations, and increase transparency through regular communication with the state.

Second agreement between Enbridge, state

Less than a year later in October 2018, the State and Enbridge announced a Second Agreement that calls for the construction of a utility tunnel beneath the Straits to house a new section of Line 5 and permanently shuts down the current segment. The agreement called for Enbridge to negotiate a public-private partnership agreement with the Mackinac Bridge Authority for Enbridge to fund the construction of a tunnel. Total cost of the tunnel was estimated to be $500 million.

The Second Agreement also added safety enhancements along the entire length of the Line 5 petroleum pipeline crossing the state, such as providing a radar system to track wave heights in the Straits to inform whether conditions require the pipeline to be temporarily shut down, install cameras to monitor boat traffic to make sure none is dragging its anchor through the Straits, guarantee Enbridge can make available up to $1.8 billion is available to Enbridge for cleanup should a spill occur, require immediate additional safety measures at 13 priority Line 5 water crossings across the state and permanently banning the transport of heavy crude oil through the pipeline.

Agreement to build tunnel

In December 2018, Gov. Rick Snyder signed legislation to create the Mackinac Straits Corridor Authority and its Board voted to approve an agreement with Enbridge to build a utility tunnel in the Straits. Among the provisions of the legislation are ones calling for the Authority to provide that the tunnel is built to last and will contain potential oil spills to prevent oil from entering the Straits of Mackinac, limit liability for the state, the authority and members of the authority, and ensure the state bears no cost.

Besides the legislation, a Third Agreement was signed that carries forward provisions of two previous agreements with the company. Under the agreement, Enbridge will undertake an enhanced inspection and stewardship regimen. The agreement also includes interpretations of the 1953 easement for the dual pipelines on the bottom of the Straits, as well as ongoing financial assurance requirements for the pipelines.

Legal challenges to tunnel

A new administration took office in January 2019, with both Gov. Gretchen Whitmer and Attorney General Dana Nessel saying publicly that they oppose the continued operation of Line 5 within the Straits of Mackinac.

There were two lawsuits involving Enbridge and the Straits pipelines and efforts to move forward with the tunnel project, one remains active.

One lawsuit involves a law that was passed by the Michigan legislature in December of 2018 which created the Mackinac Straits Corridor Authority and authorized it to enter into the Tunnel Agreement with Enbridge to build a new tunnel which would be owned by the Authority. In response to questions raised by the Governor, the Attorney General issued a formal legal opinion that the legislation was not properly enacted under Michigan’s Constitution and should be considered void. Enbridge challenged that ruling. The lower court ruled that it had been properly enacted and that the agreements entered into pursuant to the law between the State and Enbridge were valid. That decision was recently affirmed by the Michigan Court of Appeals, and not appealed to the Michigan Supreme Court.

A second suit was brought in June of 2019 by the Attorney General against Enbridge seeking to void Enbridge’s use of the 1953 Line 5 easement and end its current use of the existing dual pipelines in the Straits. No decisions have been reached in that proceeding at this time.