The upkeep of Rotorua's controversial Hemo Gorge sculpture will cost ratepayers about $5200 every year.
New details have emerged from behind-the-scenes of the sculpture's installation after a Local Democracy Reporting official information request for communications between the council, Kilwell Fibretube, Waka Kotahi NZTA and road engineers regarding the sculpture.
The emails also revealed Rotorua Lakes Council was cautious to reveal a helicopter would be needed to transport the sculpture for fear of a negative public reaction.
As a result of the investigation, Local Democracy Reporting can also reveal the sculpture will cost about $1000 to wash every year and about $30,000 to repaint every seven years with specialised UV protective paint.
Asked why the sculpture needed to be painted with specialised paint Nyalic, Kilwell Fibretube chief executive Craig Wilson said it had UV protection and extended outdoor surface finishes from deteriorating in the sun.
Wilson said Kilwell's involvement in Te Ahi Tupua project was "a good learning experience" in project management and production processes.
Emails obtained through the information request show a draft council "news item" regarding the sculpture was shared with a Waka Kotahi NZTA communications adviser by a council communications adviser on March 19, 2019.
In the draft, a comment note stated: "Have concerns about mention of a helicopter at this stage - that will likely draw further negative attention to it, particularly around cost."
The tracked comment suggests rewording the news item to say the transportation method was still being considered.
Asked why the council was cautious to publicly release the mode of transport, a council spokeswoman said the transportation method was shared with the public in May 2019.
"Prior to this the project team were still working to confirm the use of a helicopter for transportation."
A March 23, 2019 Rotorua Daily Post story revealed the mode of transport was likely to be a helicopter after an official information request at that time showed Kilwell made a presentation to the council on February 7, 2019 that indicated so.
The spokeswoman also confirmed the cost of upkeep of the sculpture - about $1000 a year to wash, and about $30,000 every seven years to repaint it, meaning yearly upkeep of the sculpture would be about $5200. The spokeswoman said this would be covered by funds set aside in the council's arts maintenance budget.
The spokeswoman confirmed installation traffic management costs of $9328.05 were covered by the council.
Confusion over sculpture's weight
In an email dated August 10, 2020, Kilwell Fibretube chief executive Craig Wilson told a council communications adviser "the sculpture weighed in much heavier than expected (almost double … so having some questions with the engineers…)".
However, it appears a measurement mistake was made at that final weigh-in and the sculpture was not almost double the weight it was expected to be and the issue was resolved.
Ultimately, a Black Hawk helicopter flown by Kahu NZ was used to transport the two helices of the sculpture from Kilwell's site on Te Ngae Rd to its location in the centre of the Hemo gorge roundabout on September 12 last year.
Originally, Beck Helicopters were going to shift the sculpture, but the weight of it was prohibitive for its helicopters.
The helicopter handed each helix off to a waiting crane, which then placed the sculpture - along with the help of a ground crew - in place on a concrete plinth at the centre of the roundabout.
An email from Kahu NZ director Mark Law to Craig Wilson quoted the cost of the Black Hawk helicopter for the job to be just over $18,000.
Wilson said he believed the sculpture weighed "pretty much what the engineers thought" - about 3.5 tonnes.
"The only explanation is that the weights recorded at Kilwell by the crane when [weighing] it were incorrect on one occasion."
This was confirmed by Gurit design engineer James Ledingham, who said the weight of the sculpture as installed was within the design specification and there had been an erroneous weight measurement, which was subsequently resolved.
Wilson said the helicopter pilot and crane had found it to weigh the "correct amount".
"Either way it was still too heavy for the original Beck helicopters as it was nearing the limits at the beginning of the project."
Wilson said the cost of the Black Hawk chopper was commercially sensitive, but it was "a lot less than $18,630", which was the figure quoted in the email by Kahu. The cost of the helicopter was covered by Kilwell as part of its contract with the council, Wilson confirmed.
He said the quoted cost for the Beck helicopter was commercially sensitive but the difference between the two was "not materially different".
He was not prepared to comment on how much Kilwell had contributed to the sculpture project over and above what was covered by Kilwell's contract with the council.
AUT Professor of Construction Management John Tookey said engineering had a "tendency to evolve" and weight blow-outs did happen but weights being nearly double the initial estimation did "not happen too often at all".
Tookey said anything built for a public space tended to be "massively over-designed" to ensure safety, and all engineering assumptions should have been checked by a peer-review process.
"Any weight additions are most likely attributable to contractors … adding additional structural material to [ensure stability and safety].
"There is a massive amount of liability for … public structures."