Key flood scheme upgrade marked

5 Jul 2019, 10:00 AM

Completion of two key parts of a wider multimillion dollar local authority upgrade of the Awanui flood scheme have been celebrated in Kaitaia.

The Northland Regional Council is undertaking a staged $15-million upgrade of the decades old scheme, with work expected to run over several construction seasons until 2027.

Designed to protect urban Kaitaia in a ‘once in a century’ type flood and a 1:20 year event in surrounding rural areas, the work is one of several key projects at the heart of the council’s Long Term Plan 2018-2028.

About 40 councillors and members of the Awanui River Flood Management Working Group, landowners, contractors, tangata whenua, community members and others gathered at Te Ahu in Kaitaia on Wednesday, 19 June to officially mark the successful completion of two key pieces of scheme work.

Carried out by local firm Kaitaia Contractors Limited, the first project involved $200,000-plus of repairs to a roughly 500-metre stretch of undermined stopbank behind Te Ahu. The second almost $300,000 project saw construction of a new emergency spillway opposite Kaitaia’s slow-moving Bell’s Hill slip site.

Attendees at the event heard the council had over the past few years been working its way through the most urgently-needed scheme repairs, with the new works delivering much-needed improvements, as well as effectively future-proofing it.

The council has been monitoring and managing the Bell’s Hill slip site for many years worried it could potentially slip into – and block – the nearby Awanui River.

Several speakers described their relief the new spillway was now in place, also expressing their gratitude to local landowners and the wider community for the backing the scheme upgrade generally had enjoyed to date.

Built on the 14,600 square metre former Firth concrete plant site, the spillway will probably only carry floodwaters once or twice a year, but crucially, should the Bell’s Hill slip ever collapse unexpectedly and block the Awanui River’s existing flow path, it should be big enough to carry the river’s entire flow.

Future flood risks in the scheme area will be mitigated largely through planned extensive modifications and improvements to stabilise existing stopbanks.

Once completed over the next few years, these will allow the river to carry up to 15 percent more floodwaters.

Without the added protection of the upgrade, a 1:100-year flood event in urban Kaitaia could cause tens of millions in damage and put lives at risk.

Seventy percent of the upgrade will be funded by ratepayers Northland-wide via a regional flood infrastructure rate the regional council introduced last year, with the balance funded locally through the targeted Awanui River Management Rate.

Man holding laptop monitoring river.

Even as an official party (pictured at rear atop the newly rebuilt stopbank behind the Te Ahu Centre) was surveying scheme improvements, regional council staff like Cory Lydford were continuing to monitor and gather data from the Awanui River itself.