Landowner Graham Milne talks about how the slip in Birkenhead affected him. / Doug Sherring
Graham Milne is not surprised by the large slip that swallowed about 50m of carpark land at Birkenhead, but never thought it would be so catastrophic.
Not only did 25 car parks disappear, but huge volumes of soil mixed with tarmac, drains and stormwater debris poured down Rawene Reserve, wiping out native bush Milne planned to turn into gardens.
Milne said Auckland Council and the former North Shore City Council have known for years about the unstable nature of the land, which he says comprises a strip of Waitemata Chaos, a greasy clay prone to slipping.
"The land has been moving for some time ... it could easily have been prevented by proper engineering right from the start," said Milne, who believed the slip will require substantial work further down the valley towards the Chelsea Sugar Factory.
In 2010, Auckland Council refused to lease Rawene Reserve to the Great Chelsea Gardens Trust, which Milne chairs. One reason given was the unstable nature of the land.
Milne wanted to turn the reserve and 6700sq m of bush he owns adjoining the reserve into a series of ornamental gardens, as well as provide public access from the Birkenhead shopping centre to the Chelsea Sugar Works.
"I'm disappointed and frustrated. What we were planning was to stabilise the land and put gardens and drainage in," says Milne, a former North Shore and Birkenhead councillor.
Milne and Graham Tucker, a resident of Mokoia Ridge Apartments, a converted toy factory overlooking the slip, have watched events unfold since the carpark was built using fill.
Graham Tucker says he's been keeping an eye on the carpark from his apartment for years and could see the slip coming. Photo / Doug Sherring.
"I could see it coming. I have been watching it for a few years, but never imagined it would get this big. Lately I have been watching the cracks get wider and wider," said Tucker.
Said Milne: "I never thought the effect could be as catastrophic as it has been."
An Auckland Transport spokesman said independent geotechnical experts are continuing to retrieve samples for analysis from the site and a drone is conducting flights every two days to detect any movement.
"Early conclusions indicate that the slip occurred as a result of poor quality fill which was exacerbated by the heavy rainfall experienced in Auckland this year," said the spokesman, saying similar sites are being checked following this year's record rainfall.
Work on the slip-facing side of a private development next to the Rawene Rd carpark has been halted as a precaution.
The resource consent application for the development at 19-21 Rawene Rd said a desktop geotechnical analysis had been done and "the site does not present any unusual ground conditions". A condition of the consent is geotechnical supervision during excavation and foundation work.
Auckland Council building control engineers have reiterated there is no indication of an active risk to surrounding buildings.
Northcote MP Jonathan Coleman said the slip was a serious issue. Residents and businesses were really concerned to know what caused the carpark to slip away and wanted a plan for businesses affected by the loss of parking.
Options to address customer and worker needs will be presented to the Kaipātiki Local Board this week, Auckland Transport said.
Coleman said that ideally there should be an independent investigation into the slip.
