The U.S. Army Corps of Engineers decided to deepen the harbor for the Cape Fear River in North Carolina. Part of the scope of this project was providing a new potable water supply line extending from Brunswick County on the mainland, cross the Cape Fear River, and supply the needs of Bald Head Island. Along with the new potable water pipe, two new power cable lines for Carolina Power & Light were also going to be installed.

Phase 1 of this work involved getting the new water pipe and power cables underneath the shipping lane. Instead of using traditional methods of digging a 20’ deep trench on the sea bottom, the Contractor of choice saved the owner over $1 million by using HDPE pipe, and a directional drill to bore a 20” diameter hole approximately 2,500 feet in length through the shipping channel to Bald Head Island. This design called for the 8” water line and the two separate power cables to be pulled simultaneously through the 20” bore, with a minimum six feet below the bottom of the shipping channel. Originally steel pipe casing was designed for use to protect the power cables, however the Contractor determined it would be easier to utilize HDPE pipe for the casing material. With design assistance from ISCO, the Engineer agreed to the change.

The 8” HDPE pipe for the water line and two power cables was fused into 200’ lengths on a barge. The Contractor and three Fusion Technicians from ISCO began the pull through the directional bore, located underneath the shipping channel. Three McElroy Fusion machines were used to fuse the 200’ lengths together. To ensure consistent fusion welds, Dataloggers were connected to each Fusion machine to record the fusion sequence.

Phase 2 will utilize concrete anchor weights to sink 5,400 feet of the HDPE waterline from the bore exit hole at the end of the shipping channel to the mainland. This phase is scheduled for completion this month.

For more information, call ISCO at (800) 345-ISCO, or locate your regional sales representative.

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