Volcanic island's cones to be rebuilt with millions of tonnes of human waste
Friday, 3 May 2019
In what is being touted as a 'world first', the landscape of a volcanic island sacred to mana whenua in the Manukau Harbour is being restored using treated human waste. Kendall Hutt reports.
Four volcanic cones on Puketutu Island that were destroyed decades ago are being rebuilt – with human poo.
The process of using treated sewage sludge (biosolids) to restore the island, known as Te Motu a Hiaroa to mana whenua, is 'worldwide unique'.
Watercare, who is in charge of the project, will save millions of dollars by using the biosolids to rebuild the cones instead of trucking it away to northern Waikato.
Not everyone was happy with this plan as certain iwi groups were initially opposed to the project. However, an agreement was reached for iwi to receive $2 per tonne of biosolids used, and everyone is now pleased that a special place of cultural significance is being restored.
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The island has been called home by key figures, both Māori and Pākehā, in Tāmaki Makaurau's history. Once known as Weekes' Island and Alderney Island, it has been a farm, a sawmill, and a quarry.
It's connected to Māngere by a causeway. When European settlers arrived, the island was only reachable by a shell bank or by boat.
In 1845, the island was sold to the first of its nine Pākehā owners for £5 and ten blankets. More than 160 years later, Watercare leased the island from the Kelliher Charitable Trust for $27 million for 999 years.
The process involved in the rebuilding of the island is simple: Watercare was looking for sustainable uses for biosolids and decided to use it to fill the quarry and rebuild the cones.
In the 1950s and 1960s, 1 million cubic yards of scoria and basalt rock from its volcanic cones were used to construct Auckland Airport's runway and what is now known as the Māngere Wastewater Treatment Plant.
VISITORS WON'T BE ABLE TO SMELL THE TREATED HUMAN WASTE
Watercare estimates 4.4 million tonnes of biosolids will have been used to fill the former quarry when this project is complete.
Aside from being used in landfills and as fertiliser, Watercare resource recovery manager Rob Tinholt says biosolids have never been used to restore a volcanic island before. It's a world first or in his exact words 'worldwide unique'.
'I don't know of anyone who does what we do. To have a monofill (sewage sludge-only landfills) of this scale of biosolids, this is unique. What's commonly done throughout the world is applying biosolids to land as a fertiliser, and another way is in landfills either as a waste put in or as daily cover material for the rubbish.'
Standing atop the edge of the former quarry in boots, a hard hat and high-vis vest, an appreciation can be gained of the scale of Watercare's project.
Spread out below are the 18 cells of treated biosolids which form the foundations of what in 30 years will be four hills to replicate the scoria cones quarried in the 1950s. The contours of the hills are based on photos from the early 1900s and the community's recollections of the island.
Tinholt says Watercare went through 52 iterations with the community and iwi to finalise the contours of the hills.
The realisation Puketutu's future lay in its restoration, rather than its development and intensification, was made in the 1990s. With Watercare's project, it has become reality.
It says there was an opportunity to rehabilitate a quarry abandoned by private enterprise and return the island to its original natural contours. The rehabilitation does save Watercare $22m, as the biosolids are no longer trucked to Hampton Downs.
Justin Smith, the man in charge of Watercare's biosolids project on the island, describes the work as being akin to making a tiramisu, although the smell is far from dessert-like.
However, visitors will not be able to smell the treated human waste below their feet, with no odours expected on completion.
Smith explains the cells are 25 metres wide, with each lift being 2m high. Mesh separates the biosolids and soil layers. He points out one cell which has an 18m lift.
The walls of the cells act as roads between the cells and Smith describes them as branches on a Christmas Tree.
Towering above to the left is the island's only remaining volcanic cone, named Te Tihi o Rakataura by mana whenua. It appears to be watching over the work on the site.
Smith says the cone has the mana, so the four hills Watercare will create will naturally be smaller.
But eyes are soon drawn from Te Tihi o Rakataura to a tractor pulling three trailers, which is coming up the road.
It is a side-tipping trailer carrying about 35 to 40 tonnes of biosolids. Per day, the causeway sees this 'road train' bring across 300 tonnes to the island.
The road train pulls alongside the cell, and one by one the biosolids fall into the pre-constructed cells. A long reach – a digger with a really long arm – smooths the biosolids down.
The first biosolids were tipped into the former quarry in 2014, and now the project is in its fourth phase of construction.
By phase five in 2024, Watercare says there will be no more construction and 'operational filling' will just be carried out.
A final 'capping' phase will see contouring, topsoil and planting done.
DUMPING BIOSOLIDS WOULD HAVE IRREVERSIBLE AND ADVERSE EFFECTS
Te Motu a Hiaroa owes its name to the sister of Rakataura (Hape), a senior tohunga of the Tainui waka. The island was the first permanent home of the Tainui waka in Aotearoa after it had been carried overland from the Waitematā to the Manukau Harbour.
Te Warena Taua, the chairman and spokesperson of the Te Motu a Hiaroa Charitable Trust, which holds the freehold title of the land, says the island is of immense cultural, spiritual, historical and ancestral significance to mana whenua – the people of Te Kawerau ā Maki, Te Waiohua and Tainui, who are recognised as the kaitiaki of the island.
'It is, in essence, the spiritual centre of Tainui within Tāmaki Makaurau and is a revered and central locale for the spiritual wellbeing of Te Kawerau ā Maki and Te Waiohua.'
Taua says Te Motu a Hiaroa is symptomatic of a legacy of desecration to ancestral maunga from quarrying, in order to fuel Tāmaki Makaurau's growth and development.
'Mana whenua in their role as kaitiaki are now left with the remnants and are attempting to restore these significant places with what limited resources they have.'
For the island's sensitive sites and places which were not completely destroyed by historic quarrying and farming activities, iwi have cultural monitors on the site to monitor and safeguard them.
Several years ago there had been opposition to Watercare's biosolids project by iwi groups and the then Auckland Regional Council and Manukau City Council.
Commissioners from both councils had turned down Watercare's publicly notified consent application and asked it to withdraw it in 2009. They said dumping biosolids on Puketutu would have 'irreversible and adverse effects' on local Māori and leave the island in a worse state than it was before rehabilitation.
Watercare rejected this decision and said the whole island was not waahi tapu (sacred) and its project would specifically ensure small, specified waahi tapu on Puketutu would not be affected.
Iwi groups lodged an appeal in the Environment Court against Watercare's plans. However, the appeals were resolved outside the court. As part of this, Watercare had reconsidered design and engineering aspects which the councils had been concerned about and engaged with iwi groups.
Now, the island's governance trust, comprised of representatives from Auckland Council, Watercare and iwi entities Waikato Tainui, Te Kawerau a Maki and Makaurau Marae, receives $2 per tonne of biosolids from Watercare. Taua says the funding has been ring-fenced for key cultural initiatives on Puketutu.
The trust's vision is to protect and enhance Te Motu a Hiaroa, a treasure, for mana whenua and the people of Tāmaki Makaurau as a special place of cultural significance. Taua says the key to achieving this is reconnecting tangata whenua back to the motu (land) through education and employment.
Strategic partnerships, like the one the trust has with Watercare, are proving vital to achieving maunga restoration across the region, Taua says.
Upon its completion in 2049, Puketutu Island will be touted as Auckland's only inner-city regional park with coastal views. The island will be a premium park gifted back to the people of Tāmaki Makaurau.
Puketutu's approximately 650 years of private ownership would also be at an end, meaning the public's access to the island would no longer be largely restricted, as it is now.
With 360 degree views of the Manukau Harbour, it is hoped Puketutu Island's visitor numbers will rival Maungakiekie's (One Tree Hill) Cornwall Park.
Decades ago E.J.Searle noted in his book City of Volcanoes: A geology of Auckland what the fate of the island would be once it's quarried.
'It is perhaps inevitable that twentieth-century man should value a flat strip of concrete more than the charming but 'useless' hills with which nature so lavishly adorned the city,' he wrote in a 1969 reprint.
Watercare's work in restoring the heart of the island – its volcanic cones – has inspired all those involved in the project.
'There's something special about Puketutu Island,' Tinholt says.