Cofferdam Protection for Transmission Tower

Sealevel Construction, Inc. was contracted to install a cofferdam protection system for the Cleco-Bogalusa Line 222 Structure 352 H-Frame Transmission Tower, supporting the infrastructure needs of Cleco Power in Bush, Louisiana.

The project required the installation of 28 AZ25-800 sheet piles at lengths of 45 ft to secure and protect the transmission structure. The piling work began on March 5, 2025, using a vibro hammer from a different manufacturer. As the project progressed, driving conditions became more challenging due to the densification of gravel and sand layers, prompting a switch to another type vibro hammer. Eventually, conditions necessitated the use of an impact hammer, and Sealevel Construction began operating the Junttan HHK5S with a sheet leg attachment on March 31, completing the installation by April 4, 2025.

Project logistics posed notable challenges. Transporting equipment and materials across the river was a significant hurdle, compounded by site access constraints. Additionally, the vibro hammers initially densified the soils, making driving progressively more difficult. However, once deployed, the Junttan HHK5S performed exceptionally well, exceeding performance expectations.

Sealevel Construction selected Junttan’s HHK5S impact hammer for its efficient setup and adaptability. The hammer’s design – without the need for traditional leads – was essential because of the site’s overhead powerline restrictions. Furthermore, the hammer’s lighter weight of around 28,000 lbs was ideal, given the crane capacity limitations during the river crossing. The HHK5S’s sheet pile legs streamlined movement from pile to pile, enhancing project efficiency even under demanding conditions.

“The setup of the hammer and the absence of leads made the hammer perfect for us. The overhead powerlines restricted a hammer & leads setup, and the limited crane capacity that was the result of the river crossing limited the weight of the hammer. So, no leads, and a weight of about 28,000 lbs met our needs. Getting it across the river was simple, and moving from sheet to sheet was a quick process with the sheet pile legs on the hammer”, said Scott Williams, Division Manager – Specialty Foundations, from Sealevel Construction, Inc.

For further information about Sealevel Construction, visit their website at: sealevelinc.com