Kaikōura flood impact matched forecasts for proposed subdivision

Flood control plans for a proposed Kaikōura subdivision expansion were put to the test in the deluge which plunged the district into a state of emergency last month.

Kaikōura District Council is considering whether to grant Cargill Station Ltd a resource consent to grow the Ocean Ridge housing development from 336 sections to 486.

Flood mitigation - as well as a proposal to increase height limits to 15 metres for business hub buildings - were the contentious issues for council, corporate services senior manager Peter Kearney told a council workshop on Wednesday, August 19.

Mr Kearney said the impact of the July 7 flood was ''in line'' with flood mitigation modelling for the proposed private plan change to expand Ocean Ridge, submitted by Cargill Station Ltd last year.

The plan change considered flood mitigation, housing density and variations to consent conditions in the development.

Mr Kearney said the Commissioners' recommendations were due to be presented to the council on Wednesday, August 26.

The applicant's flood mitigation proposal considered a one-in-500-year flood event from the Kowhai River, a 30 percent increase in flow due to climate change, a 1.5 metre increase in sea level, and a two metre aggradation of the riverbed.

More than 440mm of rain fell on July 7 and 8, which left the Kowhai River in flood and brought down millions of cubic metres of shingle.

''The modelling that was done by the applicant, and where the breakouts happened was pretty much where they were expecting,'' Mr Kearney said.

The council favoured a height limit of 11 metres in the business hub, in line with the District Plan and other commercial buildings in the district.

But as there were no submissions opposing the height limit, Mr Kearney said legal advice indicated there was ''minimal basis'' for not accepting the 15 metre height proposal.

Council chief executive Will Doughty said the hearing process was extended due to last month's weather event, as the Commissioners wanted to consider how the flooding might impact on planning provisions.

The council had previously been due to consider the Commissioners' recommendations at its July meeting.

Whatever the outcome, the sub-division will remain capped at 168 sections until the Green Lane access route is opened.

Green Lane will link Ocean Ridge with the new Vicarage Views subdivision, local schools and the town centre.

There were 28 submissions received, with 19 in support.

Four were initially opposed, but those submitters had since either withdrawn their submissions or were now in support.

Among the concerns raised by the submitters was the impact of 150 extra houses, which could represent 10 percent population increase, based on the district's existing population of 4300.

But Mr Kearney said given the relatively high proportion of housing in Kaikōura going into holiday homes and AirBnB (around one-third) and a conservative estimate of housing growth, the impact would be spread out.

''The more important issue is how quickly the houses will come on line and we think realistically it will be about eight homes a year, so it will take until around 2048 until they are built.''

■