Auckland ratepayers are facing a bill of up to $10 million to repair landslides caused by heavy rain in the region.
The scale of the problem has seen Auckland Council employ a programme manager specifically to deal with landslides, Michael Cairns, as it became too much for the operational management and maintenance team to deal with on a case-by-case basis.
Head of operational management and maintenance, Agnes McCormack, says to put the estimated $5m–$10m cost of repairs in context, her annual budget for storm damage of $600,000 is generally underspent.
Council estimates there are more than 1000 slips in Auckland – more than 90 on public land. There are around 18 on public land in the Hibiscus & Bays Local Board area including at least eight on the Hibiscus Coast.
In addition there are the slips that affect the road corridor – these are dealt with by Auckland Transport (AT) and include a substantial one on Hobbs Road, which is currently under repair, and one on a clifftop on South Ave (HM August 16). Hibiscus Matters requested details of slips affecting local roads, and the estimated cost of repairs from AT but did not receive the information back prior to deadline.
Mr Cairns says that each site is unique but issues that Council needs to consider include safety, stability, vegetation, removal of material and hazards such as trees, earthworks (and associated resource consents), the impact on flooding and erosion, public access and the effects on built structures.
Each slip is assessed and categorised. There are two local sites listed by Council as ‘completed’ – one on Whangaparaoa Road, Army Bay and another, more vaguely described as “Whangaparaoa Road, Whangaparaoa”.
Three fall into the “relatively simple to remediate” category. These slips pose little risk to the public, with only minor works required and are generally open to the public, although some may have caution tape around them as a temporary measure. They are Glenelg Reserve, Red Beach; Shakespear Regional Park and Island View Drive Gulf Harbour.
Slips in Matakatia Recreation Reserve and Ardern Lookout Reserve, Stanmore Bay fall into the “relatively straightforward to remediate” category. These are slips where private residences or public structures may be affected, or they may be located in a tidal zone. Work required could involve earthworks, removing structures, stakeholder liaison, vegetation removal and planting.
Just one is listed as “relatively complex to remediate”. This is the slip that happened at the end of May on Arkles Bay Walkway (HM June 1 and July 19). Slips such as this require geotechnical investigation, stakeholder engagement and arboricultural input. Resource and building consents, procurement and property legal designation, site access and contractors are all factors to be considered.