Costs to remove asbestos from areas of Auckland Council's Civic Administration Building has been put as low as $5 million even though the material's existing is being cited for the $3m sale price.
Justine Keane, previously JLL research director, said it would cost between $5m to $10m to remove the remaining asbestos in the building.
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But Panuku Development Auckland announced on Friday that asbestos was a factor in reaching that $3m figure.
Allan Young, Panuku's development director, said: "The cost of removing asbestos from the building, preserving heritage features consistent with a category A heritage status, and intensifying the land with housing and commercial spaces will be extremely costly so we are pleased that we were able to find a partner willing to take on this important work adjacent to Auckland's most significant civic space."
An agreement "settled" this week between Civic Lane the council which the council said "reflects the exceptional costs of asbestos removal and heritage restoration requirements, and which will enable the building to be developed in a way that will meet all of council's design requirements and objectives for the project as outlined by council when it made the decision," a statement on Friday said.
The Herald reported in 2014 how in 1989, 350 tonnes of asbestos was removed. Five years ago, Keane put asbestos removal and refurbishment costs for the 14,300sq m building at $34m to $53m.
The building could become a B grade office building, but it also "screams apartment conversion", he said in 2014.
The sale is opposed by councillors Mike Lee and Christine Fletcher and mayoral candidate John Tamihere.
Lee said today he wanted to know how much the asbestos would cost to remove and see a council document where this was revealed.
"Utterly contemptible", said Fletcher on Friday of the $3m price.
Tamihere said he wanted the Serious Fraud Office to investigate the deal but mayor Phil Goff said he would welcome such scrutiny and defended the sale, saying the agreement was made to save ratepayers $80m and "breathe new life" into the central city area.
Goff said the tower, which was designed in the 1950s and built in the 1960s, remained empty because it was an expensive job "that not too many developers found attractive".
"The building is riddled with asbestos and it has a Category A heritage listing so it is a very difficult project," Goff said. This settlement means that building can be restored and refurbished without burdening ratepayers more than $80 million in restoration costs", Goff said last week.
In 2012, then-council chief executive Doug McKay said the $93 million cost of refurbishing the building for the 450 staff in it was not economic. Demolition was an option, he said. The building was not listed as a heritage structure but had architectural merit.