Tunnellers under Auckland believed a briefing about a cancer-causing mineral was "potentially inflammatory", newly released documents show.
City Rail Link construction Photo: Kethaki Masilamani
Auckland University researchers have begun an $8 million study to find any deposits of the rare mineral erionite beneath Auckland and gauge health risks.
A briefing they gave late last year upset City Rail Link (CRL) and Watercare's Central Interceptor tunnellers, documents released under the OIA show.
"Both projects are specifically referenced in the briefing paper ... 'Erionite in Auckland bedrock and resultant malignant mesothelioma: an urgent need to assess the risks of tunnelling in Auckland," the two agencies wrote to researchers in November.
"We have concluded that there are some potentially misleading and inflammatory statements made in the briefing paper."
These could give rise to "unfounded accusations" that CRL - a Crown entity - and Central Interceptor "are not managing the safety of health impacts of the construction work adequately".
They then detailed the "extensive precautions" they were taking, even though they had never found any erionite and believed it was a very low risk.
They quoted one of the researchers telling them: "It's hard to imagine it's in the Auckland CBD."
CRL has repeatedly stressed it backs the new erionite research.
So little is known about where erionite is, that even the maps identifying five places around Auckland and Coromandel with the mineral are in question.
The maps were "misleading", said Auckland Council chief engineer Sarah Sinclair in the OIA documents.
The map reproduced by CRL, lists erionite as "confirmed" at an abandoned quarry on Te Henga Road in Waitakere; Opanuku Stream near Henderson; Castor Bay; The Tor at Torbay; and in Coromandel at Fletcher Bay.
A council geologist had concluded there was "no definitive evidence" of erionite in these five places, and the source information "may have been misinterpreted", Sinclair said.
Erionite could only be confirmed with advanced testing not available in New Zealand, and the council backed the research going on now to find out for sure where it was, she said.
'What work has been done?'
The documents show tunnellers again bristled at attention paid to erionite, in July this year.
"Unfortunately it seems that the issues have been again raised in the media in a manner that we consider inappropriate," the chair of the New Zealand Tunnelling Society wrote to the university researchers, citing an RNZ story.
"Is there any evidence to support the notion that this is a significant risk in Auckland as implied?"
The CRL chief executive, who had been copied in, responded that they had spent "a lot of time discussing this last week" with the project's health and safety manager. "We are happy with our position."
Auckland University Associate Professor Jenny Salmond said the research was in its very early days and they looked forward to sharing it when it was done.
The documents also show Worksafe's High Hazards Unit in September 2019 asked "what work has been done (if any) on determining whether the rock types being tunnelled throught might contain erionite?"
City Rail Link's general manager of health, safety and environment responded that they'd had a watching brief on it "for a while" in preparation for developing a strategy if erionite was encountered as the underground rail was put through the CBD to Mt Eden.