Rock risk too great

16:00, Dec 03 2012

Homeowners forced to abandon their Port Hills properties will be upset that they are the victims of a ministerial decision going against the advice of officials.

Upset also will be those who regard the minister, Gerry Brownlee, as dictatorial and ruled by whim. A less partisan evaluation will judge the minister as making a sensible and considered decision.

Brownlee did what cabinet ministers are paid to do: listen to the advice of experts and the public and then make decisions taking into account all the issues involved.

In this case, Brownlee was faced with the pleas of those who wanted to stay in their rockfall-threatened homes and the advice of officials who said some properties could be made safe in a cost-effective way. He rejected the pleas and advice because it would involve Christchurch City Council in continuing expenditure. Also on his mind must have been the untested ability of bunds and fencing to halt quake-induced rockfall and the equitable treatment of property owners on the hills and flat.

Brownlee was also immune to the advice that mitigation would be less costly than recourse to the red-zone offer. The savings would be "relatively small", the officials said, and even that minor saving was dependent on landowners paying for the upkeep of the protection devices.

The construction of the bunds and fences would inevitably be more expensive than estimated and their upkeep would inevitably be delayed or ignored, involving the city council - and insurance companies - in expensive disputes with landowners that would be funded by ratepayers. Moreover, it is likely that a case could be made in court that mitigation was the council's responsibility as the council granted the right to build in dangerous areas.


The city council is responsible for building on the edges of cliffs, under them, on flood plains and on liquefaction-prone ground. Such dangerous siting of structures has been going on since the beginning of the Canterbury colony but it should have stopped when we learned that we lived in earthquake country.

Christchurch has the chance to undo some of the poor consenting. The red zones map the areas that should never be rebuilt, the TC3 designations warn of the instability of land and the Port Hills have in many areas been designated as lethal. Brownlee is acting in full awareness of that third designation - awareness that his critics do not have.

Those of them being forced off their hills' properties are understandably disinclined to accept that remaining there poses unacceptable risks. They have lived in dramatic landscapes and the prospect of moving to the featureless suburbs must pall. But sentiment does not count in the face of the evidence of the dangers of rockfalls, slips and the doubtful effectiveness of mitigation. It has been gathered in great detail, using state-of-the-art equipment and has been internationally peer-reviewed.

Even if the landowners refuse to accept the evidence they should question their willingness to reside under rocks and cliffs. Common sense - not just science - should tell them that cliffs collapse and rocks are disgorged, events that can kill people. The risk is not just to the landowners but to their families, visitors and those who might have to attempt to save them.

Brownlee has understood that commonsense imperative to move the cliff-dwellers on and he should not be shouted down.

The Press