Fish farm and carbon sink
published the first concrete outcome of its consultations in May – a ‘‘vision and objectives’’ statement.
This October, it delivered a raft of material to present 10 different ways the red zone could be carved up – ecological restoration such as wetlands; attractions for locals and tourists; recreation including water sports, golf and cycling; orchards and market gardens; and clustered housing on pieces of remediated land. Yet the resulting colour-coded maps marked 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 possibilities should be boiled down to a 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.
It helps to know a bit of his background. Alexander has a reputation in Christchurch for being an innovator and problem solver. He ran the Britten Racing team in the 1990s until John Britten’s death from cancer.
Another sideline was making prosthetics for paralympians. Alexander helped with the legs that double amputee Mark Inglis used to climb Mt Everest.
But in recent years, he has switched from ‘‘nuts and bolts’’ engineering to water-based projects. He has consulted on salmon farm designs in the Mackenzie basin and, working with Banks Peninsula Ma¯ ori, designed the channel used to open Wairewa/Lake Forsyth to the sea, helping relieve its nutrient pollution.
Alexander reveals that before the earthquakes, a more ambitious plan was brewing to link Wairewa and Te Waihora/Lake Ellesmere by a 4km long canal.
The idea was to create a new joint outlet in the middle. There was talk this canal could double as the long asked-for site of a rowing venue for Christchurch.
Alexander says he was even toying with the idea of iron fertilisation of the nutrient-heavy outflow. ‘‘Start growing the marine food web there and you’d get the krill coming back – the red tides. Then you’d see the whales following the food.’’
The bays of Banks Peninsula could be full of Southern Right whales again, as well as the lakes being cleaned up. You can see where his thinking was going on big picture environmental solutions, Alexander says.
Then he got involved with the Avon red zone through whitebait research and the Nga¯ i Tahubacked Mahinga Kai exemplar project in Anzac Drive Reserve.
A tidal pump running either side of 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.
So Christchurch could become an international example of how to go a step better in using nutrientladen wastewater to create an actually healthier local ecosystem.
‘‘We could demonstrate to the world you can take your treatment plant that is puking out nitrogen and phosphate, and instead of sticking it down a pipe and forgetting about it, you could use it to drive the bottom of your marine food web.’’
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.
‘‘It wouldn’t be changing the ecosystem to something it’s never been. You’d see all the things you’d expect to see. Gurnard, flat fish, kahawai. They’re all there now. It’s just a long way between any of them.’’
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. It would form a whitebait hatchery that fed a resident population of salmon and eels as well as increase the general biomass of the bay.
‘‘The canals would be 20m across when full at high tide. Then they’d drop down to about 6m wide and 1m deep at low tide.’’ 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.
Alexander imagines Bromley with a culture pond next door, a second small pipe within the big pipe to deliver a controlled trickle of starter photosynthesisers.
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.
‘‘It could be like the wilds of Alaska where they’re just streaming in. Tourists in the central city would be standing there with their jaws dropped. Those salmon could get all the way to Avonhead Park to spawn.’’ 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 land was red zoned because it moves like jelly. The channels would be vulnerable to the 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.
Chipping in, Regenerate Christchurch chief executive, Ivan Iafeta, says the groundwork still needs to be laid for any red zone decisions.
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, 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.
Evan Smith, spokesperson for the Avon-O¯ ta¯ karo Network, 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 underway.
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.
‘‘We could demonstrate to the world you can take your treatment plant ... [and] use it to drive the bottom of your marine food web.’’