Thousands of Christchurch homeowners must have wastewater tanks installed because of the risk of liquefaction.

The Christchurch City Council, the Stronger Christchurch Infrastructure Rebuild Team and the Government will spend more than $82 million installing wastewater tanks at about 5500 homes as part of new pressure sewer systems being introduced to some parts of the city.

Council water and waste manager Mark Christison said parts of Parklands, Woolston, Halswell and areas near the river and close to the red zone would require the new system.

"[The tanks] are the most resilient solution for households in areas with land damage, prone to liquefaction," he said.

Simply replacing the existing gravity system would be a "disservice" to communities and "potentially a huge waste of ratepayer funds", he said.

The council was considering a rates remission to offset the small cost of running the pump, he said. The council would also maintain the system, even though it would be on homeowners' land.

People who did not want the new system would have to go through a disputes hearing but no other options were being considered, he said.

Some residents, however, say they are concerned about electricity costs, where the tank will go and how to deal with the alarm system attached to it.

Parklands resident Karen Brandon said she was unhappy with the lack of options, hurried time frame and "loss of democracy". "This is just so typically Christchurch. Things happen to you, not with you," she said.

Brandon, whose Inwood Ave property is technical category 3 land, said if "proper infrastructure" could not be supported after the quakes then land should have been red-zoned.

"A lot of Parklands wanted to go red . . . I didn't but apparently this area can't take a gravity system any more," she said.

"We're told what we can and cannot do with our homes, we're told our schools are closing and merging and now we're told we're having tanks put in because there's no other options."

A petition against the planned new system has been set up on change.org.nz and has so far attracted more than 70 signatures.

The petition reads: "As citizens of Christchurch, New Zealand, we object to SCIRT's intention to install CCC infrastructure on our private properties, namely pressurised wastewater tanks. We believe that council infrastructure should be on council land not our private properties."

Christison said installation of the tanks was already under way in some parts of the city because "tough time frames" meant agencies needed to push ahead.

Derek Lachut, of Environment One Corporation, which developed pressure wastewater systems in the 1960s, said the ground conditions in some parts of Christchurch made traditional gravity systems "very difficult to support".

The new systems were typically used on mountainous terrain or coastal flats with high water tables or in rural regions, he said. They were suited to Christchurch because it was prone to liquefaction. Pressure systems had more flexible pipes that were laid at a shallower depth, could provide storage in the event of a power cut and perform better during quakes, he said.

SCIRT is holding a meeting for residents at 7.30pm today at the Parklands Baptist Church in Queenspark Drive.

- © Fairfax NZ News

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