Parnell sinkhole could cost Auckland up to $3.3m a day - report

The Parnell sinkhole has not only left Aucklanders with a terrible stench but a shocking price tag, new research has found. 

Economists have found the cost of the sewer collapse could cost the city up to $3.3 million each day. 

In September this year, a sewer collapse saw a 13-metre-deep sinkhole open up in the Auckland suburb of Parnell. The report said the sinkhole, in part, was caused by the storms in Auckland earlier this year. 

The rupture of the sewer resulted in untreated wastewater flowing into the Waitematā harbour at a rate of hundreds of litres per second.  

Surrounding beaches were immediately black-flagged, with no swim and no fish recommendations in place. It would be a month, and hundreds of millions of litres discharged before the overflow was fully brought under control. 

A report from the NZ Institute of Economic Research found the impact on ecosystem services ranges between $50.9 million and $166.6 million for the duration of the sinkhole event, or between $1.02 million to $3.33 million per day. 

Traditionally in New Zealand when infrastructure fails, cost figures look at just the price of repairs, replacement and sometimes inconvenience. However, this costing has priced the associated impacts around natural capital. 

The report is based on an analysis earlier this year that put the value of the Hauraki Gulf Marine Park upwards of $100 billion to New Zealand and provided annual flows of value to New Zealanders in excess of $5 billion per year. 

That traditional approach leads to two poor outcomes. First, we end up under-valuing the natural environment. Second, we end up under-investing in resilient local infrastructure. 

"This is a conservative figure. It recognizes that the area in question was only part of the Gulf, it does not price impacts on mauri, and it assumes no lingering impacts. But it helps put into context the fact for this event the natural capital impacts were significant," the report said. 

Appearing on AM on Wednesday, the report lead Michael Bealing said it shows that impacts on natural capital goods and services should form part of cost-benefit analyses for infrastructure investment. 

"The fact is climate change is going to put more pressure on our infrastructure and the risks associated with storms becoming more frequent and severe will increase over time. So, this means we might need to think about how we invest in more resilient infrastructure," he said. 

"It's like a canary, a warning, to say we need to look at this more closely because the environmental factors are changing."

Watch the video below of lead report author Michael Bealing speaking on AM. If you can't see it on your app, click here.