Auckland Airport prepares for ‘extreme deluges’ with mega stormwater pipes

Wednesday, 25 October 2023

Auckland International Airport, which was flooded by extreme rainfall in January, is installing more than 3 kilometres of new stormwater pipes, some big enough to stand up in, as it prepares its infrastructure for the future.

The airport is installing 3.5km of stormwater pipes underground as part of the biggest airfield expansion since it opened in 1966, with six new aircraft stands.

The 250,000m² airfield expansion was underway before the Covid-19 pandemic but was paused in March 2020.

Chief sustainability and master planning officer Mary-Liz Tuck said upgrading and modernising the airport’s infrastructure meant boosting future capacity and resilience – both to the aeronautical assets but also the utilities that underpinned airport operations.

“A major component of the airfield expansion is a significant upgrade to the stormwater management system for the western end of the airport. It’s a big catchment area – imagine more than a 100 rugby fields – covering a paved airfield, future cargo precinct developments, and the surrounding land,” she said.

“As Auckland Airport plans for the future, we need to prepare for both the regular rainfall we get in Auckland but also some of the more extreme deluges that come with climate change like those we experienced earlier this year, causing the international terminal to flood.”

The airport suffered significant flooding after heavy rain during the Auckland Anniversary storm on January 27, the wettest day in Auckland’s history, which sent the region into a state of emergency and grounded all planes.

Reports at the time said passengers and staff were stranded as the airport terminals and roads were flooded.

During the peak of the storm, over Auckland, rainfall rates of up to 80mm an hour, and up to 180mm in three hours, were recorded in some places, causing severe urban flooding, slips, and widespread damage to housing and infrastructure.

The airport’s new stormwater system includes 1500 individual sections of pipe each measuring up to 2m in diameter, which will capture stormwater flows from more than 100 hectares of land north of the international terminal, directing it away and into an innovative new treatment system.

Featuring wetlands and biofiltration within a stormwater pond, native plants will clean the water before it flows into the Manukau Harbour.

A bird-proof netting cover for the pond will make sure it does not become a habitat for wetland birds, which could pose a risk to aircraft.

Tuck said the system could treat three times the volume of water compared to a similar sized traditional stormwater pond.

The airport had looked at the impact climate change would have on its infrastructure and undertook a full review of its stormwater calculations after the historical rainfall in January that caused flooding, she said.

“We’ve always used the delivery of major infrastructure as an opportunity to upgrade the utilities, including stormwater, which provide the important backbone for airport operations,” she said.

“We need to get it right, and for us that means making certain stormwater systems going in across the precinct can handle weather extremes.”

The project is being constructed by Fletcher Building’s Brian Perry Civil business.