Christchurch City Council’s proposed new wastewater scheme for Akaroa is budgeted to cost Christchurch ratepayers over $107million. When the Council lodged its consent application in June 2023, it claimed that the new system would irrigate 100% of the treated wastewater to land, meeting the Ngāi Tahu desire for an end to the disposal of treated wastewater to Akaroa Harbour.

The Council had to concede that this was overly optimistic after its own consultants reviewed wastewater flow modelling and found the proposed new system will overflow treated wastewater every 2 to 3 years, sometimes for prolonged periods. Following closed workshops held with Ōnuku Rūnanga, the Council now intends to discharge those overflows through the sea wall in front of Akaroa’s Recreation Ground onto the foreshore, a concept the Friends of Banks Peninsula environmental group and many others find abhorrent. “It’s absurd that any overflows are expected from a brand new wastewater system, particularly one that is this expensive,” says Friends of Banks Peninsula Chair, Jan Cook. The group has posted a recent report from PDP consultants on its website (fobp.org.nz) setting out the overflows and results of the workshops.

“The problem of overflows is caused by the high levels of stormwater infiltration into the Akaroa sewer network”, says Ms Cook. “The Council has carried out some repairs to the pipes, but by its own admission, it has not managed to significantly reduce the problem in high rainfall events or prolonged wet weather.”

This means that a large, highly complex and increasingly expensive system is required to manage not just human waste, but predominantly stormwater - water that must be treated and pumped for many kilometres, with a disposal system that involves 35 ha of land, 700 kilometres of irrigation pipes with millions of drippers and 10 massive industrial storage tanks. Even so, the new system will still not be large enough and discharges of treated wastewater to the Harbour are inevitable. The Friends of Banks Peninsula will be strongly advocating that these must be to an area where they will be quickly dispersed by currents, and not to the foreshore in the heart of Akaroa or any other shallow upper harbour area.

Ōnuku Chairperson Rik Tainui has stated that currently raw sewage is going into the harbour up to nine times a year and the new scheme will reduce this problem. Information from the CCC website shows that raw sewage overflows occurred on 15 occasions in the last five years. Of these 10 were due to heavy rain and 5 to broken or blocked pipes. The new wastewater scheme will not address these overflows, which result from the poor condition of the sewer pipes.

Delays in the process lie with the Council, with faulty flow meters, incorrect modelling and procrastination in dealing with the leaking pipe network all leading to a constantly changing and increasingly complex proposal.

The Friends of Banks Peninsula and other community groups are actively and constructively engaging to try to help the Council to find a solution that ideally eliminates all wastewater from the harbour, is simpler and less expensive to operate, fosters re-use and provides resilience in the face of a climate changed future.

Comprehensive repair of the sewer network would minimise all overflows, giving Akaroa the safe and resilient wastewater system that is desired by all of the community.

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