Ports of Auckland wants to dredge 2.5 million cubic metres of sediment from Waitematā Harbour

The future of Auckland's port has been the focus of intense debate. Photo / Michael Craig

Ports of Auckland has applied to dredge 2.5 million cubic metres of sediment from the Waitematā Harbour over the next 15 years.

POAL says it needs to deepen shipping channels to accommodate the increasing size of cargo ships, to cater for the city's growth, with more than 600,000 additional people expected to be living in Auckland by 2043.

The application comes as discussion intensifies over the future of the port and its location, with a leaked Government working group report this week recommending it be moved to Northland in the next 15 years.

In a resource consent application POAL says currently the largest container ships it handles carry up to 5000 twenty-foot containers (TEU).

Ports of Auckland wants to deepen the shipping channel in the Waitematā Harbour to allow for larger cargo ships. Photo / Michael Craig

Shipping lines want to bring 6000 to 7000 TEU ships here in the next two to three years, and in the future POAL wants to see "New Panamax" ships here that can carry around 12,000 TEU.​

The 6000 to 7000 TEU ships required a depth of 14m, and New Panamax ships 15.2m.

To allow these ships POAL wants to deepen the channel from 12.5m to 14m deep on the straights and 14.2m deep on the bends, making up the depth difference by working within tidal windows.

POAL is also applying to remove 15,000 tonnes a year over the next 35 years as part of maintenance dredging.

The dredged material would be mostly fine sediment, and be dumped at an authorised site 50km east of Cuvier Island as part of a 35-year consent granted by the Environmental Protection Agency for a volume up to 3.7 million cubic metres.

Where the proposed dredging would occur. Image / Ports of Auckland

Forest & Bird raised concerns at the time about the potential impacts of the sediment on marine ecosystems.

POAL spokesman Matt Ball said all material as part of the EPA consent would be tested for contaminants. The majority would be uncontaminated mudstone, and any contaminated material would be disposed of in a landfill.

POAL already holds two maintenance dredging permits, one allowing for 15,000 cubic metres from shipping channels, and another for 35,000 cubic metres from berths and approaches to the port.

In consultation concerns were raised about underwater noise and risk to marine mammals, impacts from the dredging and sediment disturbance on marine life, potential toxicity of the dredged material, and the long-term future of the port and larger ships.

In a cultural assessment, Coromandel iwi Ngāti Whanaunga raised concerns around impacts on the water quality of Te Waitematā, the ecosystems and its surrounds should an accident occur.

They requested appropriate management measures be in place, and that the activity included practices to restore and enhance the health and wellbeing of Te Waitematā, Tīkapa Moana, Hauraki and its environment.

Ngāti Whanaunga also requested to fund a three-year educational programme that promoted mana whenua values and cultural responsibility.

The consent application comes as a new report, prepared for the Government by the Upper North Island Supply Chain Strategy working group, says the port should be moved to Northland, starting now and finishing within the next 10-15 years.

A group of influential leaders have also launched a campaign to have the port shifted to "unlock the full potential" of the city's waterfront.

Ngāti Whātua Ōrākei, which owns the land on the other side of the road from the port, has also been advocating for the port to move to open up the waterfront, and this week unveiled its proposal.

The consent application is open for submissions until December 19.