Q What happens next?

A The City Council will debate the issue this month or in November and decide which of the ECan commissioners’ decisions it wants to challenge. In the meantime, Council staff will be talking to interested parties to see which disagreements can be resolved without having to go to court.

Q How much extra will an ocean pipeline cost?

A A report last month says there is a difference of about $39 million between what the Council already has said it will pay ($33.5m) for treatment works and other environmental improvements and what they think it will cost ($72.4m) if a pipeline is added. However, if they take out the UV plant ($6.4m) and the landscape and recreational amenity ($14.4m), the difference is about $18.1m.

Q Does an ocean outfall mean sewage in the surf?

A No. There is no chance any council in New Zealand will ever again get permission to put untreated or poorly treated wastewater into the environment. CCC will keep upgrading the quality of its treatment at the Christchurch plant and there is no suggestion this upgrading work should stop or be scaled back.

As well, the ocean outfall being talked about would be at least 2km off the beach – about seven times the length of the New Brighton Pier. And the pipe would have a series of emitters over the last 400 metres which would mix the outflow as much as possible with the seawater. Scientists who reviewed the public health work done on the project say that, even without UV treatment, there is “minimal predicted impact on beach swimmers”.

Q So will the Estuary be safe for swimming? A According to a group of scientists who went over all the public-health work done so far on the wastewater question and looked at new national water-quality guidelines, removing the outfall from the Estuary would improve the quality of its waters. But they thought that unless more work was done to keep other contamination out of the Heathcote and Avon rivers, the Estuary’s beaches could still be poor places for people to play in the water.

Another group of scientists looked at environmental factors and said it would mean a “pretty significant” cut in the amount and degree of sea lettuce growing in the Estuary. The water’s colour and clarity would also improve, they said.

Q Why can’t we recover the nutrients and the water and re-use them?

A The short answer is the cost. Most places that use systems to extract water from wastewater do it because they have a dire shortage of water. Staff told a meeting last month that these systems could cost up to $180m to install and up to seven times as much as the current plant to operate each year.