Geotech enginners believe constructing a pallisade wall is the best way to protect sections at Kotata Heights from slipping.
Photo / Michael Cunningham
Geotech enginners believe constructing a pallisade wall is the best way to protect sections at Kotata Heights from slipping.
Photo / Michael Cunningham
An underground wall will be built to protect slips on a new housing development in Whangārei, not far from areas earlier identified in geotec reports as risky.
Whangārei District Council has allowed land developer TDC Ltd easement over a council-owned esplanade reserve adjacent to the Kotātā Heights subdivision in Morningside for the installation of an underground palisade wall.
This is to protect sections planned within stage 4C and 4D of the subdivision from subsidence as well as sections further uphill of the development.
The palisade wall is an engineered land stability structure. It is fully buried beneath ground level and covered by approximately 200mm of soil.
Engineering reports commissioned by TDC identified the most effective place for the wall was outside the company property boundary on WDC land, which is located below the site.
A report by engineers Tonkin + Taylor to the council in November 2019 found more than a dozen houses on stage 2 at the nearby Kotātā Heights may become unstable if the land moved, leading to weaker foundations and damaged land, buildings and infrastructure.
WDC then put building consent applications on lots deemed most at risk on hold, and more than a year on the situation has not changed.
TDC, owned by Tony Davies-Colley, will cover all costs related to the legal, survey processing and engineering of the easement.
Under Section 48 of the Reserves Act, the Minister of Conservation has delegated the responsibility of considering easements over council vested reserves to councils.
A pallisade wall will be built over WDC esplanade reserve in Morningside to protect land slips at Kotata Heights.
Photo / Michael Cunningham
As the palisade wall would be fully located underground, WDC said neither ongoing material effects on the reserve were anticipated nor will the infrastructure affect the rights of the public. Public consultation is therefore not proposed in this instance.
"Once constructed, public use of the reserve will not be permanently affected or impaired. Under the consent, the land must be revegetated so it is unlikely to be used for recreational purposes."
WDC said there was the potential to create a walkway/cycleway within this esplanade area, but this was not currently funded in the 2021-31 Long Term Plan. The proposed wall would not impact on any future walkway/cycleway.
WDC infrastructure development manager Alison Thompson said building consent applications that have been put on hold would remain that way until further information was received.
No further land movement has been noticed since January this year, she said.
In August 2019, Anthony Stringer and his wife - who lived at nearby Manuka Pl in Raumanga - were moved to temporary accommodation after a landslip made their house uninhabitable and damaged WDC infrastructure.
WDC believes work carried out on a development by former Whangārei mayor Stan Semenoff resulted in the slumping of land and forced the Stringers to leave.
More than two years on, Semenoff is still working with geotech engineers and WDC to come up with a remediation report.
