The channel dredging, seeking to increase the depth from the present 13m to 15m over a period of up to 15 years, was to accommodate larger container vessels which are yet to be seen in New Zealand waters. In mid-May, Maersk changed the size of its vessels on routes around New Zealand.
Instead of the present ships carrying 4100 TEU's (20ft equivalent units), with a draft of 12.5m, they will from August 1 run 2900 vessels, with a draft understood to be between 11.5m and 12m.
Port Otago was this week given consent to dredge a 13km section of the lower harbour channel and dispose of up to 7.2 million cu m of spoil 6.5km out at sea. The consent includes extensive conditions and monitoring over several years.
About 75%, or 148 of the submitters on the proposal, were against the dredging, and the consent approval is subject to a month-long appeal period.
When contacted, Port Otago general manager of infrastructure, Lincoln Coe, said no decision had been made to start dredging.
"[However] we will be taking a more measured approach to the dredging time-frame," he said.
A decision would be made once the appeal period expires, and even if Port Otago decides to begin "nibbling away" at dredging from the present 13m depth to 13.1m-13.2, it could be six to 12 months before that operation began.
However, Mr Coe highlighted that the consent was to allow Port Otago to go beyond the present 13m maximum, and that conditions, monitoring and consultation groups would all be engaged before seeking to increase the depth beyond 13m.
If in the future Maersk signalled the return of deeper draft vessels, Mr Coe said the additional dredging to 13.1m-13.2m would give Port Otago a "head start", should 13.5m eventually be needed.
He maintained Port Otago had always planned to do the dredging over stages and 15 years could still be the time-frame to complete work to the maximum, newly-consented, 15m depth.
In Maersk dropping its weekly direct Southern Star transtasman service to Australia, Port Otago will lose 10%, or about 22,000 TEUs during the next year. The container loss is neither imports nor exports, but in the "trans-shipment" of mainly empty containers; ship, to wharf, to storage to another ship.
Lyttelton Port of Christchurch has exchanged 2600 containers from four vessels since the latest major earthquake on June 13, and is still working on wharf and pavement reinstatement. While repair work is still under way, container exchanges have been slower than normal and the port company has asked that delivery of export cargo "be delayed as long as feasible" while the backlog of vessels is dealt with.
