Good start to Awanui River flood works

Regional council engineer Sher Khan, left, and manager Joseph Camuso in December at the start of summer work, with the remains of the old concrete works buildings cleared at Kaitaia as part of a $15 million upgrade of the Awanui flood scheme.

As well as making visitors and locals happy, the dry summer has also provided a "dream start" to the roughly $500,000 of works that effectively mark the beginning of a $15 million upgrade of the Awanui River flood scheme.

The Northland Regional Council awarded two contracts to Kaitaia Contracting in December, Te Hiku councillor Mike Finlayson saying great progress was being made thanks to a drier than usual summer.

Fine weather has meant a dream start to the job, with a new emergency spillway/stopbanking under construction in Kaitaia, where the Firth concrete plant used to be. Photo / NRC

One contract (for $213,000 excluding GST) involved repairing a roughly 500m stretch of undermined stopbank behind Te Ahu, with the other ($280,000 excluding GST) for the construction of a new emergency spillway opposite the slow-moving Bell's Hill slip site, upstream from the Allen Bell Drive bridge.

Finlayson said work on both contracts was being done at the same time, and were originally scheduled for completion in late March, but would likely be finished ahead of schedule.

"This scheme's quite a few decades old, and while we've been working our way through the most urgent repairs it has needed over the past few years, these new works will deliver much-needed improvements, as well as effectively future-proofing it for many years," he said.

"The NRC had been monitoring and managing the Bell's Hill slip site for many years, worried that it could potentially slip into, and block, the Awanui River.

"To see the new spillway taking shape there is a great relief, both in my role as the local councillor but also as a Far North resident, as the wider upgrade is designed to significantly boost flood protection in and around Kaitaia."

Designed to protect urban Kaitaia in a 1:100-year-type flood and a 1:20-year event in surrounding rural areas, the work was one of several key projects at the heart of the council's long-term plan 2018-2028.

The emergency spillway was being built on the 14,600sq m former Firth concrete plant site, purchased and cleared by the NRC last year.

"Once completed, 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 river's existing flow path, it'll be big enough to carry the river's entire flow," Finlayson said.

Meanwhile the scale and cost of the total upgrade meant work, much of it weather-dependent, would be carried out in stages over several construction seasons through to 2027.

Future flood risks would be mitigated largely through extensive modifications and improvements to stabilise the existing stopbanks, which would enable the river to carry up to 15 per cent more floodwater.

"It's very important work; without the added protection this upgrade will offer, a 1:100-year flood in urban Kaitaia could cause tens of millions of dollars' worth of and put lives at risk," he said.

Seventy per cent of the work would be funded by ratepayers Northland-wide via a new regional flood infrastructure rate, with the balance to be raised via the targeted Awanui River management rate.