Kings Bluff Raw Water Transmission Main – Phase 2

The Kings Bluff Raw Water Transmission Main – Phase 2 is a project for the Lower Cape Fear Water and Sewer Authority (LCFWASA) that enhances system capacity and reliability for multiple counties in Southeastern North Carolina. Designed by McKim & Creed and installed by Garney, the project adds a 54-inch spiralweld steel water transmission main parallel to an existing 48-inch prestressed concrete cylinder pipe (PCCP) line.

Phase 1 of the Kings Bluff program was completed in 2022, with Northwest Pipe Company supplying approximately 14 miles of 54-inch spiralweld steel pipe. Phase 2 extends the parallel line by approximately seven miles, adding system redundancy to support a reliable water supply for communities in Pender County, the Cape Fear Public Utility Authority, and multiple industrial users. Combined, the two phases represent approximately 21 miles of steel pipeline manufactured by Northwest Pipe Company for the Kings Bluff program.

A key challenge within this phase was the Cape Fear River Crossing, which includes approximately 800 linear feet of 54-inch spiral-weld steel pipe installed by Garney’s marine division. Steel pipe was selected as a cost-effective alternative to the ball joint ductile iron pipe (DIP) originally specified in the design, delivering considerable construction savings while providing a durable, performance-based solution for the underwater connection. The pipe was manufactured at Northwest Pipe Company’s Parkersburg, West Virginia facility and features a polyurethane lining and exterior coating system engineered to provide durable corrosion protection in the submerged environment.

To support subaqueous installation, the crossing was fabricated in four flanged sections. A ballast pipe was secured to each piece before being placed into the river using two cranes positioned on the riverbank near downtown Wilmington. The pipe sections were then transported upriver by tugboat, filled, submerged into a pre-excavated trench, and assembled underwater by Garney’s specialized marine installation crew. Once installed, the river crossing tied into the remainder of the seven-mile Phase 2 alignment, which consists of cement mortar-lined, polyurethane-coated steel pipe.

Delivering 21 miles of 54-inch steel pipe across two phases required close coordination among LCFWASA, McKim & Creed, Garney, and Northwest Pipe Company to align design, manufacturing, and field installation — including the complex river crossing. The completed parallel transmission main will strengthen regional system redundancy and provide a reliable, long-term raw water supply for the communities and industries that depend on it.

Once the decision was made to proceed with steel pipe, NWP stepped up immediately. Under strict time constraints, their team prepared and finalized submittals, fabricated, coated, and delivered the pipe on time with no quality issues. They were professional, responsive, and worked closely with our schedule and project needs throughout. NWP proved to be not just a supplier, but a reliable partner from start to finish.

— Garney