Port Latta HV Offshore Cable Upgrade

The HV Offshore Cable at Port Latta.
Conveyor belts transport iron ore pellets along the 1.8-kilometre-long jetty to be loaded on to ships.

Contact Group’s northern technicians recently completed a unique project for Grange Resources, an upgrade of the mining company’s HV offshore cable at Port Latta in north-west Tasmania.

Our highly skilled team was selected to carry out the replacement of the HV (high voltage) offshore cable, which powers the processing plant’s 1-point-8-kilometre-long jetty and associated infrastructure.

Contact Group’s HV Operations Supervisor, Stuart Styles, said it was a really interesting job, that required hours of research and preparation, with the cable of critical importance to Grange.

Contact Group’s northern technicians recently completed the successful upgrade of Grange Resources HV offshore cable at Port Latta.
Contact Group technicians installed replacement cables which were 2.25-kilometres long.

“They had parallel 3.3 kilovolt feeders running offshore which I believe were close to 50 years old and continually failing, holding up ship loading operations,” he said.

The replacement cables were 2.25 kilometres long each, which proved a challenge to install.

Working with Grange Engineers, Stuart said it was decided to carry out the installation in three cuts, two of them at 875 metres each and the final one at 500 metres.

Cranes were used to install the HV offshore cable at Port Latta.
Cranes were used to move the cable drums which weighed 3.5-tonnes.

Contact Group technicians installed them in succession, then joined them up and tested them.

But the work wasn’t straight forward.

“If we were going to do it with cable rollers like we normally would, we would need thousands of them and it just wasn’t financially viable, so we had to research other products and materials until we found something that did the job perfectly,” Stuart said.

“That took us three weeks to put down, but the product worked a treat, and in the end, we were winching about three metres of cable a minute,” he said.

Cranes were used to install the HV offshore cable, with the cable drums weighing 3.5 tonnes.
Around three metres of cable was winched per minute.

The installation of the HV offshore cable was a huge success, because of close relationships built with other industries and Tasmanian businesses.

“We were able to pull in some favours from other industries to access specialist equipment, which was a game changer. The cable drums themselves weighed 3.5 tonnes, so we had to have a driven roller on shore and with that we managed to have the majority of the cables winched in in a couple of weeks,” Stuart said.

But the weather was a challenge.

“The weather was a real unknown. Some days we were working a kilometre offshore halfway along the conveyor belt, and when Stanley disappeared under rain, we were 15 minutes away from shelter,” he said.

Technicians joining the HV offshore cable.
Contact Group technicians clocked up about 27-kilometres of walking per day.

Luckily the team had access to one of the company’s specialist vehicles and trailers.

“But the western side of the jetty where all the services run is foot traffic only, so I think one day I clocked up about 27-kilometres of walking,” Stuart said.

He said most the technicians were doing 20 plus kms a day and deserved a big shoutout for all their hard work.

“They did a really good job, especially staying away from their young families for extended periods of time and working long hours when required.”

The cable was installed in three cuts, before being joined and tested.

Stuart said they all relished the opportunity.

“It was really rewarding to see the final results of such a long process. It was a high risk, high reward job, and to get feedback recently from Port Latta that their feed rates are up, was fantastic.”

He said they had five ships come in over the Christmas period and the cable didn’t miss a beat, so it’s been a great result for Grange.

Well done to everyone involved!

The completed installation of the HV offshore cable.
The cable has enabled much faster feed rates for Grange Resources.