Keynote Speaker: Big Lines, High Winds and Soft Ground: Helical Pile Foundations at an Unprecedented Scale-PPT Presentation

PPT Presentation

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The Commodore–Waterford–Churchill (COM–WF–CH) transmission project in West Bank, Louisiana, covers 90 miles of new 230- and 500-kV lines. It includes 915 structures and extensive foundation work in challenging conditions: 150-mph design winds, soft soils, difficult access, and limits on helicopter payloads.<br /><br />For the 60-mile Commodore–Waterford section, the team designed foundations for parallel 230- and 500-kV lines, using helical piles and vibratory caissons. The 30-mile Waterford–Churchill section includes 500-kV lattice structures supported by helical-pile foundations and anchors. Engineers assessed 50 structure-and-foundation combinations and refined the design with the selected contractor, optimizing foundations, access, materials, and installation methods. The final approach removed the upland/marsh distinction, eliminated grouted helical piles, assigned caissons to all deadends, and reduced helical-pile diameters.<br /><br />A testing program established design capacity and installation criteria. Twenty-eight pre-production load tests assessed tension and compression capacity, load-deflection behavior, torque correlations, and time-related setup effects. Results generally validated the design assumptions. Production proof testing and retorques were also planned to verify installation quality and performance.<br /><br />Construction required coordinated fabrication and logistics. Thousands of helical piles, hundreds of grillages, and more than 500 vibratory caissons were manufactured in Louisiana using U.S.-sourced materials. Seven staging yards supported delivery; materials moved overland to upland sites and by helicopter to marsh locations. Specialized excavators, marsh buggies, cranes, and vibratory hammers were used for installation, supported by full-time field engineers and inspectors.

Keywords

transmission project

West Bank Louisiana

230-kV lines

500-kV lines

helical piles

vibratory caissons

foundation design

load testing

marsh construction

helicopter logistics