Part of the cliff was cleared in late June before a shipping container barrier was installed. Photo / Bevan Conley
Part of the cliff was cleared in late June before a shipping container barrier was installed. Photo / Bevan Conley
Work to strengthen the cliff face which came down on to Anzac Parade twice within a matter of months could get under way in the coming weeks, according to the landowner.
Stephen Carle, who owns the land where the slip occurred, said the high-tech strengthening work would involve inserting 30large steel poles nine metres into the cliff, before concreting over the face.
He said the work is to be completed by GSI, the same group that did the strengthening works for the slip-prone cliffs on SH1 near Kaikōura.
The site has been watched closely by Waka Kotahi NZ Transport Agency since 2018, when a small slip left the road reduced to one lane for a few days.
The cliff stayed in place for the following two years, but the area has been the site of two slips this year, the first overnight on March 9, and the second on April 5.
After the March slip, the road was again reduced to one lane under stop-go traffic management while engineers inspected the cliff face.
A report completed on March 22 by Beca and Higgins and released by Waka Kotahi to the Chronicle under the Official Information Act, said the risk to motorists was 'moderate', but advised that the road could open as long as the debris was cleared and a 'catch area' was established between the cliff and the road.
The Anzac Parade slips in March and April have cost almost $200,000 in total, as at June 14. Photo / File
The road subsequently reopened, but a second, larger slip occurred overnight just days later on April 5 - about 15 minutes after a magnitude 3.9 earthquake struck near Masterton and was felt in Whanganui, the report said.
The catch area worked as intended with most of the debris falling clear of the road.
However, the road was again reduced to one lane after an updated report by Beca and Higgins.
This report recommended that a loose block on the cliff face must be removed, or the road completely rerouted over a small portion of Kowhai Park before the road can reopen.
Work to remove the loose earth was undertaken in early June, with an updated geotechnical report stating that a temporary shipping container barrier could be utilised until permanent works are completed.
Carle said that it's his understanding that permanent work on the cliff will begin in the coming weeks, with contracts currently being finalised.
"It shouldn't be too far away, which is good if we're going to be getting any more of this wet weather," Carle said.
Stephen Carle's Wairere Rd property sits perilously close to the edge of the cliff. Photo / Bevan Conley
The process will involve drilling 30 150mm-wide holes into the cliff - each about nine metres long.
A steel rod with an anchor at the end will be inserted into each hole, before the hole is pumped full of concrete.
Steel mesh will then be placed over the cliff face and attached to each of the rods, before sandstone-coloured shotcrete will be poured over the mesh, creating the appearance of an untouched cliff.
"An engineer told me that each rod can take 1000 tonnes of weight. There are 30 rods there."
Negotiations are still under way around the cost of the works, understood to be shared between Waka Kotahi and the landowner.
Carle told the Chronicle last month that he's expecting to be $150,000 out of pocket.
The property atop the cliff is also proving costly for Carle, with the building currently under a dangerous building notice, meaning it can't be inhabited until the strengthening work is complete.
Waka Kotahi/NZ Transport Agency has spent almost $200,000 on keeping the public safe from the slip.
As of June 14, Waka Kotahi had spent $193,479 on costs associated with the slip - $110,221 of that solely on traffic management, with stop-go contractors in place during daylight hours for two months.
