Kordia innovation upgrading high voltage transmission towers

Faced with the repair and upgrade of the tower footings of a 22,000 volt (high voltage) overhead transmission line to meet system design life, our customer required an innovative yet practical solution.

Faced with the repair and upgrade of the tower footings of a 22,000 volt (high voltage) overhead transmission line to meet system design life, our customer required an innovative yet practical solution.

The six kilometre transmission line runs up the side of a mountain carried on overhead conductors supported on eleven large steel H-frame towers and connects a major broadcast site to the Ergon Energy power grid.

The transmission towers constructed in 1972, were showing their age. Located in extremely steep terrain in an environmentally protected rain forest in far north Queensland was challenging. The hazardous yet critical project required careful and detailed planning with onsite inspections identifying structurally unsound tower foundations, requiring immediate repair and upgrade.

The customer required a specialist tower refurbishment subcontractor and Kordia was selected. Works included the upgrade of 22 foundation blocks, installation of temporary anchors to support the string of 11 structures, and the replacement of all guy ropes and support wires.

The logistics of these works were challenging. Facilities at the summit were serviced by a privately owned cable car, which ran parallel with the 22 kV line. The HV support towers were accessible with use of a height safety system or via a walking track, taking a full day to traverse from the summit.

Access was difficult for a majority of the structure and meant that all equipment needed to be airlifted.

Helicopter services were used to facilitate all works and tiger tailing (visual warning flags) of the existing lines, ensuring all loads were elevated safely and efficiently between the power lines.

The scope included digging 3m down manually to expose existing foundations, enabling them to access the blocks and upgrade the footings. Allowing the install of new reinforcement bars, guy anchor rods, and formwork.

The project was delivered ahead of schedule, on budget and safely, reporting zero lost time injury (LTI). The project is testimony to Kordia’s capability and ability to perform works on various types of tower structures and difficult terrain conditions, including the hazardous high voltage environment.