Mackay Port Authority Dredging restores navigational depths Article first published on Friday, 21 January 2005 @ 10:47:45 AM

The final phase of an extensive maintenance dredging and seabed levelling program at Mackay Harbour is nearing completion.

Late last year, the Port of Brisbane dredge Brisbane removed about 100 000 cubic metres of material from the main harbour swing basin and port berths. About 40 000 cubic metres of material is deposited in the harbour by incoming tidal waters each year.

The $400 000 dredging program has enabled the Mackay Port Authority (MPA) to economically restore navigation depths – making it possible for the port to safely continue handling up to Panamax class cargo vessels.

Environmental manager Scott Keane said the viability of the port hinged on maintaining depth levels.

“If we don’t dredge the harbour it will restrict the draft of the vessels using the port,” he said. “This will make us less attractive internationally because ships won’t be able to load as much cargo and that in turn would increase freight rates for cargo shipped out of Mackay.”

Mr Keane said the seabed levelling program currently underway was the final phase of a new three year dredging program being conducted by the MPA.

The bed leveller – a 12 metre long blade, similar to a large dozer blade, towed by a tender vessel – planes off the ‘high spots’ left behind after dredging.

“Digital computer equipment and echo sounders on board the tender vessel enable the operator to precisely monitor the levelling work,” Mr Keane said.

“It’s important all ridges and high spots are removed as this will maximize the size of the ships able to use the port.”