Line 5 Poses On-land Explosion Risk for Michigan Residents

On August 1, a natural gas pipeline operated by an Enbridge subsidiary exploded in Kentucky. The blast killed one person, injured six others, and blew 30 feet of pipeline out of the ground, resulting in a crater that is 50 feet long, 35 feet wide and 13 feet deep. About 66 million cubic feet of natural gas was released by the explosion, with the resulting fire destroying multiple structures and burning vegetation over approximately 30 acres of land.

Although public attention has rightly focused on the risk of a catastrophic oil spill from Enbridge’s Line 5 pipelines at the Straits of Mackinac, FLOW board member Rick Kane points out that the risk of a similar explosion is also possible because of the natural gas liquids (NGLs) running the length of Line 5’s 645-mile transit through Wisconsin and Michigan. Here is Kane’s analysis.

Enbridge’s Line 5, a legacy hazardous liquids pipeline, poses a major explosion and fire safety risk to citizens and property along its entire length while it transports natural gas liquids (NGLs). This risk is particularly high for the Line 5 segments north and south of the Straits of Mackinac. Why is this issue not being investigated as part of the proposed tunnel project so that citizens and first responders living along the Line 5 hazard zone know the current risk and likelihood that permitting and replacing the pipeline will pose in the future?

The severe consequences of a Line 5 failure and crude oil release into the Straits have been widely publicized. Construction of a tunnel with a new pipeline is now being pursued as a risk reduction approach against a major crude oil spill disaster. However, a tunnel does not reduce the risks posed by Line 5 across the Upper Peninsula and Lower Peninsula where a rupture could release crude oil into hundreds of lakes, rivers and streams, some even leading to the Great Lakes. Nearly absent from the studies and debate are the threats and catastrophic consequences to human safety and property posed by Line 5 while it transports NGLs.

FLOW highlighted the NGL risks in 2018. The risk was on display on August 1 when a large legacy natural gas pipeline in Kentucky exploded, causing one death and sending five residents to the hospital. Unfortunately, the Kentucky incident is only one of many in recent history.

Pipelines are the safest transportation mode for crude oil, NGLs and especially natural gas. However, there are a wide range of pipeline design specifications, materials transported, pipeline ages, physical conditions and operating environments. Line 5 is a legacy pipeline, well past its designed retirement age, operating in an extremely sensitive environment and transiting through several populated areas. Unlike wine, a vintage pipeline does not get better with age; government and industry statistics show that failure rates increase dramatically for legacy-class pipelines. Several major incidents in recent years call into question the reliability of pipeline industry failure prevention programs to justify the continued operation of these pipelines.

A Line 5 failure during the transport of NGLs could have consequences beyond the Kentucky failure and other too-typical natural gas pipeline failures:

• Natural gas (methane) is transported as a compressed gas. The NGLs in Line 5 are mostly propane with some ethane and butane that are gases compressed to a liquid state when transported by pipeline.
• When a natural gas pipeline failure occurs, a rapidly, vertically expanding gas cloud ignites, creating a huge flaming torch. Many people reported that the fire from the Kentucky explosion reached 300 feet high.
• When an NGLs pipeline fails, liquid is expelled quickly, forming a large vapor cloud that moves with the wind until it finds an ignition source. Then the vapor cloud ignites, and an explosion and fireball occur with a shock wave, flame front and radiative heat wave moving out from the explosion area.
• The potential energy (explosion and heat) from an NGLs explosion can be much greater than from a natural gas break as NGLs have a higher caloric value and the quantity of energy released can be much higher.
• The risk study developed by Dynamic Risk Systems, Inc. for the State of Michigan in 2017 contained an NGLs deep water release scenario in the Straits that would result in a flame front of almost one mile. Contrast this with a ground level release upstream or downstream of the Straits where the release quantity could be much higher as the distance between pumping stations and shutoff valves is greater at ground level and near populated areas and valuable property. Computer modeling of potential release scenarios near populated areas would provide estimates of fatalities, property damage and important evacuation zones for law enforcement and first responders.

The Kentucky pipeline explosion is still being investigated but preliminary information indicates that the pipeline is similar in size, age and construction to Line 5. Corrosion is believed to be the cause of the failure, and as in other similar incidents, Enbridge is trumpeting the touted pipeline loss prevention program and the reliability of inspections with “smart pigs” to justify continued operation of legacy pipelines.

Issues and Questions   

• The entirety of Line 5 will need to be replaced at some point if the tunnel project proceeds. Does the State of Michigan understand the risks for transporting NGLs in legacy hazardous liquid pipelines, and have assessments been conducted and verified by third-party experts? Are citizens living in the potential impact zone aware of the risk they face?
• Do property owners and citizens know that a flurry of permit requests for Line 5 “maintenance replacement” will be issued if the tunnel project is given the green light, as was done with Line 6B/78 after the Kalamazoo River disaster in 2010? A similar piecemeal, preventative maintenance and capacity expansion approach is currently being used on Line 3 in Minnesota—a pipeline with an increasing number of failures that Enbridge says needs to be replaced and is 10 years younger than Line 5.
• Importantly, emergency response organizations along the Line 5 route should complete pre-modeling of NGLs release scenarios to understand potential explosion overpressure and flame envelops and have evacuation scenarios ready to use. The modeling required is more complex than typically done by first responders for hazardous materials spills; they could underestimate the size of an evacuation zone.
• The State of Michigan regulates gas pipelines but not hazardous liquid pipelines such as Line 5. Why not? Cost is not the answer: other states have taken on the task after disasters occurred; the cost is covered by inspection and audit fees charged to the pipeline companies. State inspections can supplement and provide local control rather than depending on the overwhelmed federal regulators from Pipeline and Hazardous Materials Safety Administration (PHMSA).
• What about a “National Emphasis Program” focused on pipeline safety starting with the largest operator, Enbridge? After a spate of major refinery and chemical facility accidents several years ago, the Occupational Safety and Health Administration (OSHA) implemented a National Emphasis Program (NEP) that focused on certain segments of the industry based on risk and accident history. Comprehensive inspections and audits addressed not only regulatory requirements but a company’s adherence to industry standards and requirements applicable through the General Duty Clause.

Accidents will continue as long as the pipeline industry uses its own standards for acceptable levels of pipeline failures and relies on current loss prevention and inspection programs for legacy pipelines. The industry is currently deciding the risk tolerance for citizens. A large NGLs pipeline rupture near a local city or village could happen again, just as Line 6B/78 dumped crude oil into the Kalamazoo River nine years ago.

Rick Kane, FLOW Board Member

Rick is the former Director of Security, Environment, Transportation Safety and Emergency Services for Rhodia, North America.  He is certified in environmental, hazardous materials, and security management, and is a graduate of the University of Michigan and University of Dallas.