Auckland’s port seeks consent for deeper channel
A deeper channel needed to safeguard Auckland's vital international supply lines
Ports of Auckland has applied to Auckland Council for consent to deepen the city's shipping channel and a resource consent hearing on the matter will be held this week.
Auckland's population is forecast to grow significantly, with a million more people expected to live here by 2050. More people means more demand for the products we all buy from overseas, which means more containerised imports and – bigger container ships.
Ports of Auckland must be ready to handle this growth.
The largest container ships calling in Auckland now carry up to 5,000 twenty-foot containers (TEU). Shipping lines want to bring 6-7,000 TEU ships here in the next 2-3 years and in future Auckland will need to host 'New Panamax' ships that can carry around 12,000 TEU.
The channel is currently 12.5 metres deep at low tide, but New Panamax ships are 366 metres long with a maximum draft of 15.2 metres. Ports of Auckland is only applying to deepen the channel to 14 metres – so how will the ships get in?
The answer is tidal windows. In common use globally and at other New Zealand ports, a 'tidal window' simply means that deeper draft ships enter or leave port when the tide is high enough.
To create a tidal window suitable for New Panamax ships to access port safely Auckland will need a channel which is 14 metres deep on the straights and 14.2 metres deep on the bends. Auckland's berth will be dredged to 15.5 metres so ships can stay through a full tide cycle.
By using tidal windows, Auckland can minimise dredging and reduce cost. It is the most efficient way to accommodate larger container ships.
The dredging will be done by the lowest impact method available - a digger on a barge. The digger will have a long arm to reach down to the seabed to scoop out material. The channel bed is mostly soft material like marine muds, mudstones and some sandstone and gritstone, which can be removed easily. No blasting is required.
Ports of Auckland asked for the consent application to be publicly notified by Auckland Council so that people could have their say on the project. Over two hundred submissions were received.
If consent is granted, work on deepening the channel could start in 2021.