Christchurch's council has been pushing back on new central government rules for housing intensification. File photo. Photo: 123rf.com
Parts of Christchurch are off-limits for further housing development because the sewage system is full.
The city council has been pushing back on new central government rules for housing intensification, but its exemption runs out next year.
An independent investigator was appointed and the council held hearings earlier this year on the proposed changes, called Plan Change 14 (PC14).
With more policy changes announced last week, councillors were under pressure to get the ball rolling.
When heavy rains hit the city in 2021, some suburbs could not flush their toilets because the wastewater pipes were full. The city council had to resort to using sucker trucks to keep the pipes moving.
It was not an uncommon sight in Aranui, Shirley and Prestons when it rained now.
All three suburbs had vacuum sewer systems installed after the earthquakes - but they were built with little room for growth.
Council acting head of planning and consents Mark Stevenson said the systems also relied on an air to water ratio - meaning they failed if too much stormwater got in.
"To accommodate further demand in the future, it would require the whole system to be upgraded simultaneously at a significant cost. It's not a system like other parts of the city where we can dig up a pipe and just replace it," he said.
Replacing the systems was estimated to cost up to $240 million, the council said.
It usually set aside less than $50m for the entire wastewater network over 10 years.
Mayor Phil Mauger was keen to ditch the vacuum systems.
"I don't like it, because I've laid lots of pipes, I can tell you what it's like. We should go to a system that we are using out in Halswell, which is little pump stations for every house, which works extremely well," he said.
The individual pumps took the pressure off the wastewater system at peak times, when it was more likely to near capacity, Mauger said.
"They're all hooked up to a main computer here in town. We can say 'right, our sewers are at capacity from six until nine at night because everyone's having a shower'.
"We can press a button and turn all those pumps off, because they've got a wee tank that can hold the stuff, then we can turn them all on at three o'clock in the morning and it makes our pipes a lot more useable throughout the day," he said.
No other suburbs were at risk of hitting their sewer capacity, and the council was only approving new housing where the infrastructure could support it, Stevenson said.
At this stage, that meant building more around main public transport routes, and in areas that had easy accessibility to services - both for residents and the council.
Climate change and natural disasters were also starting to have an impact on planning, he said.
"We've identified properties that should not be intensified because of the risk that would be posed by rock falling in the event of a major earthquake. So we want to avoid development in areas which are going to pose a risk to life in those circumstances.
"There's other hazards on the flat land as well, including flooding," Stevenson said.
Ngāi Tahu Property had just applied to build 55 residential homes on the site of the former Aranui Primary School - in a wastewater capacity area.
It declined RNZ's interview request, but confirmed the application had been lodged and said it would await the council's assessment.
RNZ had viewed its application, which stated it was aware the area's sewage system was full.
According to the plans, each house would have its own independent pump unit, like those in Halswell.
It was unclear where the latest central government housing announcement would leave the city, Mauger said.
"Staff will now need to work through the implications of the announcement and brief us so we get a full picture. Fortunately we have over 30 years' worth of expected demand covered in our existing zoning, and this will only increase through our National Policy Statement-Urban Development proposals in PC14," he said.
"Our existing District Plan is already enabling of mixed use developments in centres, as well as providing for small scale retail activities within residential areas. Whether further relaxation of the existing standards is required, may be the key focus for any future plan change," Mauger said.
Christchurch City Council will vote on some of the government's proposed housing intensification changes under the Resource Management Act on 4 September.