May 27, 2011

Tough decisions ahead for Christchurch rebuild

By New Zealand correspondent Dominique Schwartz, ABC News
Friday, May 27, 2011

Christchurch residents are anxiously awaiting a land report that will help determine whether parts of their quake-ravaged city will be abandoned.

Already technical experts are warning that tough decisions will be needed - in both the central city and suburbs - to avoid the deadly mistakes of the past.

The report is due to be handed to the New Zealand government within weeks.

Christchurch is naturally a very wet place with meandering streams and wetlands. There are about 8,000 springs under the city.

Landscape architect Di Lucas has been studying and working with Christchurch's terrain for decades.

She says the recent earthquake has had a massive effect on the landscape.

Ms Lucas says the devastation wrought by February's quake on the city centre may, in part, be explained by the river banks or levees left by the city's old waterways.

"The old 1850 map plotted the streams in central city. It shows they are right under a lot of blocks and a lot of buildings and there is a pattern of them right through," she said.

"It is not an issue necessarily the water, but with the earthquake, the levees seem to be an issue."

The Pyne Gould Corporation (PGC) building was the second most deadly site in the CBD when the quake struck.

Eighteen people died in the building and a royal commission will investigate why some buildings failed and others did not.

Ms Lucas says the underlying levees may be a factor.

Several streams meet beneath the PGC building. It was on an old levee that may have exploded.

The quakes liquefied the ground underpinning many areas around Christchurch - cars and houses sank into in grey, stinking sludge.

Engineers can fix almost anything, but cost is a major issue.

Ms Lucas says hard decisions are going to have to be made about which areas should not be rebuilt in.

"We've seen the liquefaction and that is where high water tables, estuarine sands... you don't want to be engineering it. I think you want to be avoiding it."

The land report that is being prepared for the Canterbury Earthquake Recovery Authority will outline land damage across the city, potential new hazards and options for remediation.

The government will ultimately then have to decide where it is putting the money up.