Akaroa wastewater scheme balloons to $167m - more than $70m over budget

Wednesday, 2 July 2025

The projected cost of a contentious wastewater treatment scheme in Akaroa has ballooned to $167 million, some $73m more than budgeted.

An alternative discharge method could be on the table - sending treated waste straight to the ocean, instead of first irrigating it through land - but that is almost guaranteed to be offensive to mana whenua and still cost $148.7m.

“There is no cheap option here,” Gavin Hutchison, Christchurch City Council’s head of three waters, told councillors at an information session on Tuesday.

“It’s either land-based, or the ocean. There’s no silver bullet.”

It comes several weeks after the council confirmed it would push ahead with work on a resource consent opposed by locals who say the scheme is too small and too expensive.

This opposition, largely channelled through the Friends of Banks Peninsula group, which hired experts to challenge the consent, found partial success earlier in the year: the consent was put on hold, pending more work from the council.

But, in the meantime, anticipated costs are rising and more preparation work than expected needs to be done.

At the Tuesday briefing, project manager Kylie Hills said the total cost could balloon to $167.2m, much more than the $94m on budget.

Foundations and ground preparation work could cost $21m more than expected. Other additional costs included $5m towards increasing storage to 24,000m³ and an additional $3m to dispose treated waste further away from shore.

“So that’s the bad news,” Hills told councillors.

As an alternative, Hills said the council could consider discharging treated wastewater directly into the ocean - an idea he said was raised by community members, but would likely be offensive to mana whenua.

While still about $54m more than budgeted, it was “a little bit cheaper” than the irrigation scheme, he said, and could also save $7.35m in operational costs over 30 years.

Hills said it was an idea worth exploring after the Government had finalised new water standards - due later this year - and more engineering work had been done.

Council staff expected to bring options to councillors for the future scheme in early 2026.

In 2020, a treatment scheme for Akaroa’s wastewater was estimated to cost between $54m and $63m. It has since expanded to incorporate a wastewater scheme for Duvauchelle.

Akaroa’s wastewater has been treated and discharged into the harbour for half a century, on land considered so historically significant - the site of a massacre - some have argued it rivals Waitangi.

The city council inherited the wastewater plant when it absorbed the old Banks Peninsula District Council’s assets and in 2007 pledged to move it.