Rebuild plan put to riled landslip victims

Engineers are sure Mulberry Place can be made stable. Photo / Dean Purcell

A North Shore housing cluster hit by a large landslip last year can be stabilised and made fit for building platforms, say soil engineers.

Yesterday, the city council issued geotechnical reports to property owners that suggested a redevelopment costing between $285,000 and $370,000.

The plan was to reinstate a condemned building platform at No 1A and to protect adjacent properties at No 1 and No 3 Mulberry Place, Glenfield.

City councillor Grant Gillon said the project was an option for the owners if they went into mediation with the council. He said the council was "comfortable" with its legal position over the land movement. But it believed mediation offered the best hope for a satisfaction to all parties.

The two units at No 1A were damaged by the slip and evacuated.

A report for the Earthquake Commission said the units were in danger from further slips within a year.

Their owners accepted a total-loss payout through the commission and their own insurers.

Under the council proposal to property owners, the units would be demolished to make room for stabilisation earthworks.

This would restore the value of the land, says the council, and it was up to the owners whether they wanted to sell, or to continue ownership and share in the redevelopment costs and benefits.

Last June's slip also affected the public road, access to the three units at No 1 and the house at No 3.

Last month, owners of three dwellings at No 1 demanded the council buy their properties.

David Thornton, who is a Glenfield Community Board member, said he acted for No 1's residents.

They were now seeking an urgent meeting with geotechnical consultants.

However, he said he was concerned geotechnical reports showed homes were still under threat and that recent repairs to Mulberry Place had not removed the threat of further slips.

Riley engineering consultancy says the slope above No 1A is "marginally stable".

A peer review by Tonkin & Taylor consultancy said it believed Riley proposals for permanent works could restore stability to the properties.

It considered enough investigation had been done to show the feasibility of remedial options.

Riley proposed a combination of deep buttress drains extending up the slope from a shear key and buttress at the toe of the existing fill soil slope.

Tonkin & Taylor said the combination of earthworks and drainage was feasible provided works took in the wider site.

After the slip, the council spent more than $200,000 on building a palisade wall to support the Mulberry Place roadway and to keep access open.