Christchurch Mayor Bob Parker has challenged the process used to condemn homes on the Port Hills at risk of rockfall, amid claims some of the homes could be spared and millions in ratepayers' money saved.
Grilling Canterbury Earthquake Recovery Authority (Cera) chief executive Roger Sutton on how the authority had reached its decisions on which homes to red-zone, Parker yesterday publicly questioned whether the council and the Government had got it right.
He raised his concerns about the quality of the decision-making after hearing a deputation from newly red-zoned Port Hills resident Tony Ging, who argued that if the council looked at homes at risk of rockfall individually, or in clusters, rather than taking an area-wide approach as Cera had done, many of them could be made safe.
The council faces having to pay $58 million towards the cost of buying red-zoned Port Hills homes because of rockfall risk.
Ging, who lives in the Avoca Valley, said that of the 168 Port Hills homeowners recently zoned red, about 50 wanted to stay in their houses. Most believed that if the council took steps to reduce the rockfall risk from council-owned land, an acceptable life-risk level could be reached, allowing them to keep their homes.
They believed geotechnical information already gathered for the zoning process could be used to design effective rockfall mitigation. Life risk, boulder trajectories, bounce heights and energy levels had been documented. Many geotechnical engineers were available who could use that information to design effective mitigation.
Ging said companies such as Maccaferri believed they could design and build effective rockfall embankments for about $5000 a linear metre. On average, the mitigation would cost less than half the value of the properties, which meant about $5m of taxpayers' money and $5m of ratepayers' money could be saved.
Citing his own property and his neighbour's as an example, Ging said the two properties had a combined government valuation of more than $1.6m. The estimated cost of constructing an 83.5-metre reinforced earth bund to protect both properties from rockfall was just over $440,000.