Revelations of "voids" discovered beneath the 246-unit Alexandra Park project in Greenlane has left a specialist asking if they were lava caves with Māori or moa remains.

Peter Crossley, a veteran speleologist formerly of Auckland University, was reacting to statements yesterday from Rod Croon, vice-president and acting chief executive of the Auckland Trotting Club about "voids" discovered under the ground at the site on Greenlane Rd near the ASB Showgrounds.

Crossley said he was not surprised to hear of large rooms of up to 4m high found on the site. The area had a number of caves due to lava flows, he said, so the voids were not unexpected.

"One Tree Hill [Maungakiekie] has lava caves on the other side, leading down to the shore," Crossley said, also referring to caves beneath Greenlane Hospital opposite the apartment project site.


"I suspected there could be caves on the site."

Crossley had tried to look into the construction excavations to see if caves were being uncovered around 2015 when ground works were busy, he said, but it was not possible to see.

If the voids or caves were near the surface, or only 1m to 2m below, they might contain bones of koiwi or moa, he said. But if they were perhaps 10m down, that was less likely because the moa could not fall into them and Māori were unlikely to use them as graves.

Peter Haynes, Albert-Eden Local Board chairman, said he did not know about the voids or caves until yesterday's Herald story and was unhappy to hear they had been filled in with concrete and grout.

'Voids in rock' discovered under 246-unit Alexandra Park caught builders by surprise

"I'm dismayed to hear about this," Haynes said, referring to one site worker who told of "rooms 2m, 3m, up to 4m high by 2m wide".

"Those were clearly lava caves," Haynes said. "I don't yet know what was in the consent for the development, but it is likely that there was nothing in the consent because lava caves that may be found are not usually included in consents."

Cave scientist Peter Crossley beneath the streets of Mt Albert. Photo/Sylvie Whinray
Cave scientist Peter Crossley beneath the streets of Mt Albert. Photo/Sylvie Whinray

The Unitary Plan had no general rules covering lava caves, he said.


"There are some lava caves specified and listed in the plan, but there are no protections for newly identified caves. There is only one lava cave at Wiri in public hands that I know of and, while there are quite a few known lava caves, many of us are fearful for the future of some of the best examples," Haynes said.

Croon, of the club which is developing the apartment scheme, yesterday revealed new details about ground conditions when construction started about four or five years ago.

"They did find rock and it was a major problem at the start and there were voids in that rock. It was common knowledge," Croon said yesterday of the site near the volcano, Maungakiekie.

"I don't know if there were caves but there were problems with the rock and I'm told there were voids. I'm only telling you what I was told," he said, referring to others who had since left the club or had died.

Asked if the council, archaeologists or iwi were called when the voids were discovered, Croon said he was not in his current role at the time and referred to one of the two builders: "We are in litigation with Canam through arbitration and can't comment further."

Croon has not responded today to questions about last night's special club meeting where members were to vote on a proposal to sell two Manukau Rd sites to repay ANZ and Westpac a $40m loan on the project.

Haynes said iwi had an interest in lava caves in the area "as many were the resting places for kōiwi, and Maungawhau and Maungakiekie were major pā settlements."

Iwi had shown interest in local caves recently, he said.

Haynes: "dismayed" about voids under apartments. Photo/Kellie Blizard

"Depending on accessibility to the caves, it may be that iwi should have been informed as a matter of courtesy, but there are no guidelines that require this I think, as for archaeological finds. Of course, if kōiwi or grave materials or were found, then it's my understanding that the rules regarding archaeological finds would apply," Haynes said.

Auckland Council's premium building consents manager Sally Grey said Alexandra Park was in a geographical area where basalt or rock flows were expected.

"As such, voids discovered during the foundation works in late 2015 were not unexpected. The owners engaged experienced geotechnical and structural engineers, who developed a robust plan to manage these issues," she said.

It was not unusual to find these sorts of conditions because they are reflective of Auckland's volcanic geology.

"This is a scenario that happens to varying degrees on many construction sites, from small residential buildings through to the largest construction sites on a daily basis," she said.