World's longest HDD project under mighty Mississippi a 'mind-boggling' accomplishment

Enbridge's Great Lakes to Gulf Coast series (Part 9)

With 25 years in the pipeline industry, Jack Olin has seen his fair share of pilot bits, drilling rigs, and pullbacks.

“But drilling projects like this don’t normally come along real often in people’s careers,” remarks Olin.

He can say that again. When Enbridge’s Flanagan South team completed a five-week horizontal directional drilling (HDD) project under the mighty Mississippi River in early September, they not only reached the final major construction milestone of the $2.8-billion pipeline project – they also set a world record in the process.

At a distance of 9,038 feet – or about 1.71 miles – Enbridge’s Mississippi River HDD was the longest such project for a 36-inch-diameter pipeline, eclipsing the previous mark of 7,400 feet previously established in Texas.

In the case of large rivers or certain sensitive crossings, Enbridge uses HDD technology whenever possible to install underground pipelines. HDD projects can be completed in a way that minimizes environmental and stakeholder impact, even in sensitive areas.

“This was a feat of engineering that’s almost mind-boggling, when you think about it,” says Dave Hodgins, Enbridge’s senior manager for the Flanagan area. “It’s amazing to think of the innovation and the technology that were brought to bear to make that possible – especially at that depth, to ensure the integrity of our pipeline and the safety of the Mississippi River.”

The Flanagan South pipeline project, which runs 593 miles from Pontiac, Ill., to Cushing, Okla., encompassed more than 4,000 workers at the peak of its construction phase, and Olin estimates that the Mississippi River HDD project required a workforce of several hundred from Enbridge, trusted contractor Michels, and drilling engineer J.D. Hair & Associates, based in Tulsa, Okla.

“We used the best engineer in the world, and the best drilling contractor,” reflects Jerrid Anderson, Enbridge’s senior director of Major Projects for Flanagan South. “It was well engineered, and well executed.”

The HDD construction technique involves drilling an underground arched tunnel – in this case, about 70 feet below the Mississippi’s riverbed – and pulling the pre-assembled pipe section back through the tunnel.

The sheer length of last summer’s HDD project posed its own challenges, and the Flanagan South team overcame them by conducting an intersect drill – with one drilling rig starting to bore on the east side of the river, near Quincy, Ill., a second starting on the west side, near Hannibal, Mo., and the two drill bits meeting in the middle.

“The trick was to keep things simple and consistent,” says Olin, who retired in December as a senior manager of pipeline engineering and construction with Enbridge, after seeing the Mississippi River HDD – and the Flanagan South project – through to their completion.

“With this project, like everything else, we made darn certain that we hit on the things that matter – safety, quality, and compliance, from both an environmental and a regulatory standpoint.”

Safe and reliable operations are the foundation of our business – and the Mississippi River HDD project team’s relentless focus on safety mirrored that of the entire Flanagan South pipeline project.

Through more than 12 million hours committed to the project, the Flanagan South team turned in a Total Recordable Incident Frequency (TRIF) rate of 0.61 – an exemplary number. The TRIF standard, which measures the rate of recordable workplace injuries and other occupational incidents, is used in virtually all industries; a TRIF rate of 2.5 or lower is considered to be good, and 1.5 or lower to be excellent.

Among other meaningful data, 79,232 Field Level Hazard Assessments (FLHAs) – the so-called “last looks” for potential hazards before the day’s work begins – were carried out by Flanagan South crews, while 26,555 safety observations were made.

“We are extremely proud of our safety record on Flanagan South,” says Anderson. “Throughout the construction phase, maintaining a safe work environment stayed top of mind with our entire Flanagan South workforce.”

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