Big dreams blue carbon in the red zone

Plans for the Avon red zone are coming back to ordinary uses like housing, parks and watersports. Could there be something more ambitious? John McCrone reports.

No idea is too big, they said. Yet maybe this one is. Wayne Alexander, an Ilam engineer and John Britten’s former motorcycle racing team manager, takes a deep breath and launches into his pitch.

The recovery agency, Regenerate Christchurch, is looking for a really smart postquake use for the 600 hectare Avon residential red zone – a project unique and ambitious enough to put Christchurch on the world map.

The talk has been of rowing lakes, eco-sanctuaries, green belt parks. Certainly all nice to haves, Alexander agrees. But pretty much what every other New Zealand city has to offer. Not especially unique.

Even the $100 million Eden Project proposed for the Avon Loop is not a first. The original Eden Project – an eco-attraction opened in Cornwall in 2001 – has now become an international franchise. Australia is getting one. China is building three.

So what is Alexander’s big idea? In a nutshell, he says, turn the lower Avon into a giant fish hatchery by carving up the abandoned red zone into a latticework of canals. Make it a refuge for whitebait, eel and salmon.

Actually it is bigger than that. The estuary and entire Pegasus Bay could become a fish farm and ‘‘blue carbon’’ scheme.

Alexander points out that Christchurch’s Bromley sewage treatment plant already dumps 4 tonnes of nitrate and 1 tonne of phosphorous into the middle of the bay each day through its ocean outfall.

‘‘It’s like a Ravensdown fertiliser factory on the shore, just giving it away.’’

Yet that nutrient load is not doing much for the ecology of the bay at the moment as iron is then the limiting photosynthetic factor. Not much extra algal plankton actually grows.

Alexander says dust the water with soluble iron sulphate and production would take off. Christchurch would have fish coming out of its ears. The red zone could anchor an aquaculture scheme on a truly grand scale.

On top of all that, it could be a pioneering blue carbon project too. Alexander says increasing the photosynthetic density of Pegasus Bay would be just the same as planting forestry blocks on land when it comes to locking up atmospheric CO2.

So is this the bold answer as to what will turn heads internationally – a 21st century city which is doing something useful with its sewage, feeding its people better, and producing a carbon dividend to boot?

If nothing else, it seems an interesting test of how adventurous the authorities are going to be in pursuing their search for the best possible use of Christchurch’s earthquake broken land.

Caution versus innovation

The red zone process has begun to frustrate some. The decisions appear to be taking forever.

Under Regenerate Christchurch, the future of the Avon red zone – an area four times larger than Hagley Park – is meant to emerge from a community-led debate.

After all the complaints about how the early phase of the earthquake recovery was too much a case of government command-and-control, this would be different.

However because so much public consultation has been going on, progress has also seemed rather cautious and ‘‘tip-toey’’.

There are the many well-aired proposals now, like an international rowing course for Horseshoe Lake and a fenced ecosanctuary next to Travis Wetland in Burwood.

Some newer ones have also been popping up, like the possibility of Avondale and Rawhiti golf clubs doing landswaps.

In exchange for giving up their own good land for affordable housing, they might get a new saltmarsh golf links somewhere like Bexley. A clever way to use the red zone to bring people back to East Christchurch without actually having to build on it.

But despite so much being said about individual projects, it has become difficult to know what is in, what is out. So far Regenerate Christchurch has only been prepared to talk in terms of high level abstractions.

The recovery agency finally

‘‘It could be like the wilds of Alaska where [salmon] are just streaming in. Tourists in the central city would be standing there with their jaws dropped.’’

Wayne Alexander