The prospect that Auckland's port could move north will take a back seat to plans to deepen the existing shipping channel and cater for larger container ships, Ports of Auckland said on Friday.
Consideration of the company's request to dredge the Waitemata navigation channel will start on Monday, when a panel will hear evidence from the 200 submitters on the plan.
Ports of Auckland notified its consent application on November 21 for what will a two-stage dredging programme, initially allowing entry by container ships able to carry the equivalent of 6,000 to 7,000 twenty-foot containers.
The second stage will cater for New Panamax container ships with a 12,000 TEU capacity, the company said. The larger vessels, which are 366 metres in length, have a maximum draft of 15.2 metres and will rely on tidal windows to both enter and leave the port, it said.
The port said the 12.5-metre channel will be deepened to 14 metres on the straights, to 14.2 metres on the bends and the berth will be dredged to 15.5 metres so ships can stay through a full tidal cycle.
North Island strategy
The port operator's initial submission coincided with recommendations of the upper North Island strategy working group to shift the port to Northport at Marsden Point or build a new port in the Firth of Thames, with a scoped cost of more than $10.3 billion plus rail upgrades.
Auckland Mayor Phil Goff said while he remains in favour of moving the council-owned port, "relocation needs to stack up economically."
Based on the economics, it is a "huge sum of money with opportunity costs for other investments and the case for moving it to Northland needs to be strong and conclusive," he said.
The working group suggested the port could be moved within 15 years, but the firm's communications general manager, Matt Ball, said the Auckland operation's lifespan would be "closer to 30 years."
The NZ Institute of Economic Research report, commissioned by the port in October 2018, said it was worth about $158 million a year to the city's economy, while the council would forgo about $100m per year in direct benefit if it were moved.
The NZIER report estimated that the use of Northport as an alternative port, will also add 138,774 tonnes of greenhouse gas emissions from additional road traffic and 92,665 tonnes from rail emissions.
The Port of Tauranga, the country's busiest export port, has an approach channel depth of 14.1 metres, with Port Otago at 14 metres. Tauranga last year had throughput of 1.18 million TEU, with Auckland second at 973,700 TEU.
Ball said the dredging process, which uses a digger on a barge, will have a low environmental impact with issues like turbidity, or floating particles in the water, at a low level.
The dredged sediment will then be barged to the disposal site, an uninhabited volcanic outcrop east of Cuvier Island under an existing marine dumping consent. That allows the port to dump up to 2 million cubic metres of material from capital works per year for the next 34 years.