Intersection Beneath The Mississippi: 7,700-Foot Bore Generates Many Challenges For Ranger

By Jeff Griffin, Senior Editor | September 2013, Vol. 68 No. 9

“The liner is being used to reduce internal corrosion and extend the life of the pipeline. The brine will only see the wetted parts of the inconel alloy connector and will not corrode like steel in brine service. The internal lining of the pipeline was all HDPE and inconel.

The coupling is under a patent pending by United Pipeline. “To our knowledge,” Thibodeaux added, “this project is the longest linked pipe of this type ever put under water.”

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The assembled pipe was laid out on 137 rollers in preparation for the pull in. The weight of the pipe string was 381,600 pounds, 190 tons. However, Simon pointed out, because the pipe was on rollers, the actual force weight was less.

“There are several engineering calculations to determine the amount of pull force needed to pull pipe that is laying horizontal on the ground and the number of rollers on the pipe section. So it is not correct to say we ‘pulled’ 381,600 pounds to get the pipe into the drilled hole. Pullback went extremely well, and the most pullback pressures experienced were 140,000 pounds. However, the pipe we pulled did weigh a total of 381,600 pounds.”

Careful timing
Time was very important to the project’s owner, said Simon.

“We were mandated by the Corps of Engineers to complete this crossing before the Mississippi River water level could rise more than 11 feet,” he explained. “Melting snow from the northern states would increase as warmer months approached. Due to these concerns, Boardwalk requested we work 24 hours a day to help expedite the schedule. Once the pilot hole was completed, we utilized four different crews during reaming and swab activities for a total of 11, 24-hour shifts. Two mud engineers from DCS Fluid Solutions and two GeoEngineers employees were on site throughout the project.”

From start to finish, the river crossing was completed in 43 days, two days ahead of schedule. Simon praised the project’s two field managers, supervisors Barry Nailing and James (Tiny) Matlock, for exceptional work on the project.

Established in 1993, Ranger specializes in the underground installation of pipelines and conduits, including directional drilling installations beneath waterways, congested areas, highways and environmentally sensitive areas.

Using a broad range of construction methods – including trenching and plowing in addition to HDD – Ranger crews have successfully completed projects in some of the most difficult geological conditions in the United States.