At a conservative growth of 5 per cent, a 2009 study found that in 20 years there would be insufficient capacity at Auckland and Ports of Tauranga to meet the upper North Island's freight needs. At this point, or sooner, further development would be needed in Northport at Whangarei.
"Under the economic growth targets in the Auckland Plan, the role and capacity of the port will need to expand even more than under standard economic growth patterns," Mr Chrystall told councillors.
However, the company in its 2008 development plan cautioned against the "inherent uncertainty" of long-term planning, citing its 1989 port plan.
In 1989, the company planned reclamation of the eastern port by 1994 and a new port by 2010. But because of improvements in productivity and capacity within the existing footprint, reclamation was delayed until 2009 and a new port has been abandoned.
The 2008 plan said that over the long-term there was likely to be one major hub port in the North Island and one in the South Island, with Auckland being the most viable and logical North Island option.
Then last month, the port took a different tack in its submission on the draft Auckland Plan, saying it was important to retain ports in Auckland, Tauranga and Northland because dependence on one port would "remove resilience and significantly increase supply chain risk".
Heart of the City chief executive Alex Swney, whose business group is campaigning against the company's expansion plans, said there were other economies to consider.
"Before we consent away our waterfront we should consider the wider implications, economic and environmental, and demand a review of the port's plan and seek a range of alternatives for Aucklanders to consider," Mr Swney said.