Big dreams and 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? 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.
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 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.
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.
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 highlevel abstractions.
The recovery agency finally published the first concrete outcome of its consultations in May – a ‘‘vision and objectives’’ statement.
This month, it delivered a batch of maps meant to present 10 different ways the red zone could be carved up.
Yet these were just colour-coded blocks marking possible categories of land-use, not the naming of actual projects.
Regenerate Christchurch chief executive Ivan Iafeta says the next big public engagement – an ‘‘expo of ideas’’ to be held late this year or early 2018 – is when the many possibilities should be boiled down to some more definite set of choices.
It is slow going. But it means something new and unthought of may capture the public’s imagination – something as leftfield as a fish farm perhaps. In his living room, Alexander grins as he unfolds a map of the red zone.
Most people will think it is a crazy notion on first hearing, he acknowledges. But it is a plan he has been working on for several years now.
He has met with Regenerate Christchurch officials to discuss it. And preliminary hydrological modelling has been done by a local firm.
Alexander got involved with the Avon red zone through whitebait research and the Nga¯i Tahu-backed Mahinga Kai exemplar project in Anzac Drive Reserve.
A tidal pump running either side of the highway to connect Travis Wetland to the Avon River, the reserve has been one of the few actual red zone projects to be started so far.
To show what could be possible in terms of eco-restoration and customary food gathering, the reserve has been planted with thousands of natives.
Then there and elsewhere in the red zone, straw bales were put out as a method to encourage inanga or whitebait spawning. It was at that point that all the bits of the jigsaw came together for him, Alexander says.
Think about it from a global perspective. The world knows it needs to get serious about combating climate change through carbon capture, Alexander says. And the land-based options like forestry are always going to be limited by space.
So the next obvious thing to do is use the ocean as a great big carbon sink – seed it with iron sulphate and get the plankton blooming.
However, that kind of geoengineering is risky and untried. There are international laws against it because who can be trusted safely to run a blue carbon project way out at sea?
Alexander says Christchurch could offer a controlled setting where iron fertilisation was being trialled inshore next to a major city. A place where thousands of eyes would be watching it constantly.
‘‘The problem is that there’s no such thing as certificated blue carbon schemes as yet,’’ says Alexander. But a 1990s Niwa coastal survey showed Pegasus Bay had, at that time, an average chlorophyll density of 6 micrograms per litre. There is a Kyoto Protocol era baseline to work with.
‘‘If you could say it was 6 micrograms, and you had doubled it to 12 micrograms, then that is an additionality just the same as planting a forest after 1989.’’
In like fashion, everywhere in the world there are coastal cities with big sewage farms, says Alexander.
And most not even as clean as Bromley. So Christchurch could become an international example of how to go a step better in using nutrient-laden wastewater to create an actually healthier local eco-system.
Alexander says it sounds like monkeying with nature. But the truth is Pegasus Bay was long ago denuded by commercial fishing. It is many years since trawlers gathered off New Brighton beach.
Getting deeper into the technical detail, Alexander says on the red zone side of things, he imagines carving 26km of meandering channels into the broken land stretching from the estuary up as far as Porritt Park – the whole length of the tidal prism.
That would create a ton of new habitat which recreates the swampy lower Avon as it used to be.
The cost of excavation should only be $2m to $4m, he says. Of course, there would be serious engineering issues to consider.
His hydrological study, produced by DHI, says the estuary would be pumping more water because of the extra volume of waterways being filled.
Flow rates could be a third faster on the incoming tide.
But then earthquake damage means the estuary hasn’t in fact been filling so well.
That has been prompting calls for costly dredging anyway, he says.
Then when it comes to the practicalities of using Bromley and its 3km ocean outfall to manage the fertility of the bay, Alexander says by his guesstimate, only about 250 grams a day of added iron might be needed.
That could be mixed with the wastewater stream to get the photosynthesis going as soon as it hit the open sea.
Another step that might be required to maximise the effectiveness of the scheme is seeding the water with the right types of plankton in sufficient quantity.
Yes, his plan is starting to get hazy at this point, he says. However the idea is that Christchurch would be doing the basic science to discover what it would take to make it all work.
If Christchurch went to the world saying it was going to use its red zone to tackle some really global problems, that would attract the international funding to pay for the whole exercise.
‘‘You’d be able to raise $100m or $200m for doing the necessary research.’’
Christchurch could wind up with both a new productive industry – a fish farm – and also leadership in the practical knowhow of blue carbon projects and eco-friendly wastewater systems.
And then think of a future Christchurch where whitebait again turn the streams milky with their milt each breeding season, where a salmon run is established that goes right through the heart of town, he says.
Back at Regenerate Christchurch’s headquarters, the eyes start to dart when the question is put directly.
Is this an idea too big, or in fact something quite possible?
Residential red zone general manager, Rob Kerr, says he has talked the scheme over a couple of times with Alexander.
Cutting a network of mahinga kai channels all the way up to Kerr’s Reach could best be described as ‘‘challenging’’, Kerr says. If nothing else, there is the lateral spread risk to consider.
The channels would be vulnerable to next big shake.
Also, strictly speaking, the sewage plant/fish farming project would be outside Regenerate’s red zone remit, Kerr says.
Really, Alexander is talking about two projects – what to do with the red zone and something else happening out in Pegasus Bay.
The plan is to first build a general picture of the possible uses. Alexander’s scheme would come under the heading of productive activities, or ecorestoration.
However, it is still to be determined where new stop-banks are going to go. And while the recovery agency is indeed asking for big ideas that will put Christchurch on the map, and attract international investment, it could be argued the red zone itself as a whole is going to do that, says Iafeta.
He says the world will be interested just in the red zone as an example of how a large area of urban land can be repurposed to answer a variety of community needs, while also dealing with a range of land-use risks, such as quake-proneness and rising sea levels.
The balance of uses is as important as it having some flagship use. So cautious support. But Iafeta says it is certainly good to have voices like Alexander to up the level of ambition.
Avon-O¯ta¯karo Network spokesperson Evan Smith is also supportive, saying Alexander’s grand approach does tick most of the boxes of the stated red zone vision.
It would be a massive ecorestoration project that could also pay for itself. Smith warns that if the red zone is treated as just a new public park, the maintenance cost is going to fall back heavily on rate-payers.
Smith says there is the obvious concern 26km of canals sounds too much. How would that fit with other lower Avon projects like a golf course in Bexley or ecosanctuary in Burwood?
‘‘Having lots of tributaries running through a sanctuary would seem a conflict, as each one would be a hole in the predatorproof fenceline.’’
But also, Smith admits, some of the early-favoured projects like the eco-sanctuary are getting a harder look now public consultation is under way.
Is it really right to build a protected habitat for dryland native species – kiwi, ka¯ka¯ and tuatara – in what is in fact an estuarine environment? Nice idea, wrong context, is the comment being heard on that.
However, Smith says Alexander is an example of the creativity being unleashed by the red zone decision being put out to the public.
The idea may go nowhere or happen in a simpler form. Ecological restoration is going to be a prime objective, regardless.
Yet, it is the kind of proposal that should wake people up to the fact that Christchurch is in a happy position of being able to make some big and interesting choices, Smith says.
Engineer Wayne Alexander sees the Mahinga Kai exemplar project in Burwood as the start of something big.
A new commercial fishing industry is possible.
Chris Mene, Ivan Iafeta and Robb Kerr.