Ports of Auckland has announced that it has been granted consent to deepen the shipping channel for the approach to the Waitemata Harbour, a move that will safeguard Auckland’s vital international supply line.
The consent allows the channel to be deepened from 12.5 m to between 14 m and 14.2 m. It safeguards Auckland’s vital international supply line by allowing larger container ships to enter Auckland’s port, such as the 366 m long New Panamax vessels with a maximum draught of 15.2 m. Tidal windows will be used to make best use of the natural water depth and keep dredging to a minimum.
The largest container ships the port can handle at present carry up to 5000 TEUs (20 ft containers). Shipping lines want to bring ships capable of carrying 6000–7000 TEUs to the port within the next two to three years, and in the future, the port will need to be able to host New Panamax ships that can carry around 12,000 TEUs.
Ports of Auckland chief executive Tony Gibson says: “The Covid-19 lockdowns have highlighted the essential role that Auckland’s port plays in the economy. A deeper channel will ensure Auckland’s port can continue that essential role for decades. By allowing larger ships to reach the port, it will also reduce carbon emissions and the cost of transporting Auckland’s freight.”
Panamax and New Panamax (or Neopanamax) are terms for the size limits for ships travelling through the Panama Canal. The allowable size is limited by the width and length of the available lock chambers, by the depth of water in the canal, and by the height of the Bridge of the Americas at Balboa. These dimensions give clear parameters for ships destined to traverse the Panama Canal and have influenced the design of cargo ships, naval vessels, and passenger ships since the canal was opened in 1914.
In 2009, the Panama Canal Authority published the New Panamax specification which came into effect when the canal’s third set of locks, larger than the original two, opened on 26 June 2016, allowing for bigger, wider and deeper-draught vessels to traverse the canal.
DISPOSAL OF DREDGED MATERIAL
The consent process for dredging Auckland’s shipping channel was unusual because Ports of Auckland asked for the application to be publicly notified, even though it was not required, so people could have their say on the project. Over 200 submissions were received, with the main concern raised being the disposal of dredged material.
Ports of Auckland acknowledges that this is a genuine concern and is committed to working with key submitters to look for ways to reduce or even eliminate the need for sea disposal.
A mechanical dredge – a digger on a barge – will be used to deepen the channel. The digger will have a long arm to reach down to the seabed to scoop out the bottom material. The bed of the channel is mostly soft material like marine muds, mudstones and some sandstone and gritstone, which can be removed by a digger. No blasting is required.