Transpower, the owner and operator of the high voltage transmission network has successfully completed the lay of a new telecommunications cable under the Cook Strait and removed offshore sections of the redundant cables.
The new fibre optic cable commissioned in mid-March connects between Transpower’s facilities at Oteranga Bay in the North Island and Fighting Bay in the South Island, and assists in managing New Zealand’s National Grid. Like the High Voltage Direct Current (HVDC) interisland cabling, the deployment is totally within the protected area of the Cook Strait Cable Protection Zone.
The deep-sea cable laying and recovery required the use of the specialist cable ship – Reliance, while people at both ends were required to connect on shore. Good weather meant the Reliance was able to complete laying the cable in the first week of March, and turn its attention to recovering the older cables.
“We had really good weather at the beginning of March that meant the Reliance was able to lay the new cable within days and then commence recovery of the old,” said Cobus Nel GM Information Services & Technology.
“There were four older cables that were targeted for removal by the Reliance, measuring in total 154.7 km. They recovered around 152km of that prior to moving on to their next assignment in Hawaii, and since then the remaining 2.7km has now also been recovered.
“From our perspective, an excellent outcome – some of those cables are nearing 30 years old so we weren’t too sure what condition they’d be in to be able to recover,” Mr Nel said.
There is still around 5kms of redundant cable in shallow water and onshore at Oteranga and Fighting Bays to be removed. This will be done when Transpower mobilise again for the annual maintenance and inspection work in Cook Strait.