THE Gladstone Ports Corporation will spend about $100 million deepening a shipping channel near the RG Tanna Coal Terminal.
The project will remove two million cubic metres of dredgings from the Clinton by-pass channel as a safety measure to protect ships berthed at the coal terminal.
"The current channel is 13 metres deep, which is fine for the LNG ships and the other, panamax class, ships which have traditionally travelled to wharves above the coal terminal as they are all shallow draft vessels," corporation chief Craig Doyle said.
"But now, with the advent of the Wiggins Island Coal Export terminal, there is a need for cape class ships, which are deeper draft vessels and we need to deepen the channel to 16m.
"The cape class vessels currently have to pass within 90m of the berthed coal ships. We knew several years ago that this could well pose a problem, and recent experience has shown that the problem does exist."
Deep draft ships displace a considerable amount of water, and the void left behind caused water to be sucked away from other vessels.
"This is a safety issue. When the ships pass the wharf, even at low speed the suction puts massive stress on the lines securing the berthed ships to the wharf. The last thing we need is to have those lines break and the ship to become free," he said.
"We haven't had that happen yet, and we don't want to see it happen."
Because the project will involve capital dredging, all dredgings will, by regulation, be dumped on land, and Mr Doyle said it was most likely they would be taken to the bund at Fisherman's Landing which was used for the majority of the recent Western Basin dredging project.
The project is small in comparison with the Western Basin dredging, where more than 20 million tonnes were dredged from the harbour floor to give LNG ships access to the three loading facilities on Curtis Island. That project cost $1.3 billion.
Mr Doyle said he expected the physical dredging to take between four and six months, but it was not likely to start until early 2017 after all environmental and regulatory hurdles had been dealt with through state and federal government agencies.
He said monitoring following the western basin project was still being undertaken and that had provided the corporation with significant amounts of data.
The corporation chief said the dredging project had been part of the port planning for some years.