Drilling project goes deep under the Mississippi River

Pipeliners work on the 4,500-foot Line 51 HDD project.

Piping Up For Technology Series (Part 10)

Innovation never stands still—there’s always a new advancement coming down the pipe. Enbridge is constantly testing commercially available technologies, and looking for opportunities to enhance existing technologies, in the areas of design, prevention, monitoring and leak detection, to keep our pipelines safe.

Our Piping Up For Technology Series, on the @enbridge blog, offers a glimpse of various research projects we’re engaged in, and the efforts we’re making to adapt and harness technology for safety’s sake. These proactive investments in innovation are intended to add another layer of safety and security to our pipeline network—and, ultimately, to the energy transportation industry as a whole.


There’s nothing predictable about Mother Nature. And that’s one of the reasons we drill deep for safety’s sake.

Late last month, Enbridge completed the replacement of a 4,500-foot section of our Ozark Pipeline near St. Louis—a successful Horizontal Directional Drilling (HDD) project that buried the pipeline 65 feet under the riverbed of the mighty Mississippi River.

The $23-million drilling project was delayed by floods along the Mississippi in early January. But those very floodwaters, caused by heavy rains across parts of Missouri and Illinois, served as validation for this innovative engineering project—and the built-in safety that HDD technology delivers.

“Because of this HDD project, the pipe will no longer be subject to flooding or high river current concerns,” says assistant project manager Lee Koppy. “While the Ozark Pipeline has operated safely for decades, this project was significant . . . positioning the pipeline under the riverbed is a win for both the environment and the economy.”

In the case of large rivers or certain sensitive crossings, we use HDD technology where possible to install underground pipelines. The Ozark Pipeline (or Line 51) HDD crossing travels more than three-quarters of a mile between West Alton, MO and Hartford, IL, with 2,400 of its approximately 4,500 feet running under the Mississippi—and another 1,200 feet travelling under a flood plain on the Missouri side.

To replace the existing line secured to the river bottom, drilling engineers from project subcontractor Southeast Directional Drilling bored an underground arched tunnel to a depth of 65 feet, and then pulled the pre-assembled 22-inch-diameter pipe section back through the tunnel.

As we do with all of our pipeline projects being placed into service, we examined all pipeline welds with X-ray technology and performed hydrostatic tests on the line.

“Southeast Directional Drilling has safely performed several hundred miles’ worth of HDD projects,” notes Lichun Zhang, a senior engineer with Enbridge’s Pipeline Integrity group, “and having an engineering representative from Lake Superior Consulting there on site helped us complete a successful drill, in spite of the challenges posed by the floods.”

Adds Mike Moeller, senior director of Enbridge’s U.S. Midcontinent Region: “This is a major accomplishment for all of the team members involved.”

Enbridge’s Ozark Pipeline carries about 215,000 barrels of light crude oil per day from Cushing, OK, to refineries in Wood River, IL, travelling a distance of about 435 miles.