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Friday, March 11, 2011

Putting the city to its biggest test

Putting the city to its biggest test

Last updated 12:00 26/02/2011
Violent Christchurch earthquakes have shown that any New Zealand city could be ravaged by a big jolt. Can we rely on our buildings to remain standing and our water system to work?

What are Palmerston North's most critical or vulnerable assets? GRANT MILLER investigates.

Scores of lives lost, dozens of people missing, hundreds of casualties, roads ripped up, buildings destroyed, homes flooded with water, communications down, power out – Christchurch is on its knees.

This time – just months after everyone survived a 7.1 magnitude jolt – the physical destruction is more than matched by the human toll, trauma, sorrow and fear.

Just hours after the earthquake violently shook South Island's largest city, it was clear there were multiple fatalities, people missing or trapped and hundreds more people injured.

Prime Minister John Key labelled Tuesday one of New Zealand's darkest days. With a magnitude of 6.3, the 12.51pm quake was not quite as large as the massive one in September, but it was more devastating because the jolt was centred so near the surface.

"No words can spare our pain," Mr Key said this week.

"Many people have lost their lives. Families have lost their cherished loved ones. Mates have lost their mates.

"These deaths are the greatest loss.

"They remind us that buildings are just buildings, roads just roads, but our people are irreplaceable."

Gradually, Mr Key moved from empathy to emphatic resoluteness.

"Though your buildings are broken, your streets awash, and your hearts are aching, your great spirit will overcome.

"This devastating event marks the beginning of a long journey for your city.

"It will be a journey that leads us from ruins and despair to hope and new opportunities. From great hardship will come great strength."

The resilience of Cantabrians will be thoroughly tested.

As if the loss of lives is not horrific enough, the damage bill will be enormous – estimates have been put at $10 billion.

And, as Mr Key points out, the region was starting to emerge from the destruction wrought by September's quake and months of aftershocks – only to be hit by the biggest shock of all.

Even the timing seemed to mock the region.

The $500 million rebuild of Christchurch's infrastructure from the September shake was officially launched less than a fortnight before Tuesday's disaster. Earthquake Recovery Minister Gerry Brownlee and Christchurch Mayor Bob Parker had taken turns handling a jackhammer in Burwood to signal the start of repairs to the city's water, sewerage and other damaged infrastructure.

Mr Parker described the repair job as massive then, and it will be even greater now.

Fortunately, there will be no lack of support from the rest of New Zealand and overseas. The devastating earthquake scenario is something every New Zealand city plans for, but everybody hopes those plans will not be tested.

What might go wrong if Palmerston North is put to the test?

The city gave us a couple of hints in recent months when two major water pipes burst under the Fitzherbert Bridge across the Manawatu River.

Those two pipes carry 60 per cent of Palmerston North's water supply, from the Turitea water catchment. The rest comes from bores.

Fortunately, the pipes did not burst at the same time.

We also have a fair idea which buildings are likely to be vulnerable.

Palmerston North City Council has a register listing 84 properties as earthquake-prone. Prominent buildings on the list include the Wesley Broadway Methodist Church, All Saints Church, the old Palmerston North police station, the Manawatu Standard building and several Cuba St buildings.

A building deemed earthquake-prone is considered 20 times more at risk of collapse than a new building. The register was published in 2001, however, and is in the process of being updated.

Local government planners across the country were already committed to learning lessons from Canterbury's September quake when this week's destruction occurred.

Palmerston North City Council, for example, has started a review of its asset management plans, which will include consideration of the damage that liquefaction could cause to its assets. Liquefaction is when significant ground-shaking leads to compression of earth, forcing water to rise to the surface.

The potential problem has raised some doubts about where Palmerston North should grow, but council staff are also pondering risks to the council's own assets.

Palmerston North City Council's portfolio of assets is worth about $1.2b.

That includes the city's roading network ($372m), water assets ($155m), wastewater assets ($177m), recreation assets ($163m) and property ($136m).

Not included in that is the value of the council-owned Palmerston North International Airport and Horizons Regional Council stopbanks, vital for containing floodwaters.

Of course, asset managers have more to think about than just contingency plans.

They also consider how levels of service may change and what assets are likely to be needed in the future. And there is maintenance.

City council special projects manager Phil Walker says the council takes a 20-year view of assets.

"Asset management is about stewardship of those assets," he says.

It goes beyond making sure assets are well-maintained for the next generation, to also planning for that generation's needs.

City networks general manager Ray Swadel says the council has to take into account expected levels of service, which can change.

When the council had problems with discoloured water, residents made it clear they expected a higher level of service. So, part of the council's response was to speed up a programme to replace cast-iron pipes with PVC pipes.

That programme is about two-thirds complete.

Mr Walker says the Palmerston North council's assets are in pretty good shape – much of the city's infrastructure was built in the 1960s and 1970s.

A renewal spike will be necessary in about 2050.

And since central government forced councils to carry out long-term planning in recent years, New Zealand councils have got their asset-management systems up to speed. But, like any city, Palmerston North has its points of vulnerability.

The Fitzherbert Bridge, for example, is critical, not necessarily because of any weakness there, but because it is so important for the city.

After the water pipe failures at the bridge, the council is investigating how to make the water system more robust.
Council water and waste services manager Chris Pepper says the gas and telecommunications networks are also critical for the city.

The integrity of Palmerston North Hospital is vital.

Other critical public assets include the Maxwells Line and Massey University pumping stations, the Totara Rd wastewater treatment plant, large pipelines feeding into the treatment plant, arterial roads in and out of Palmerston North, the upper and lower Turitea dams, the Turitea water treatment plant, the main supply pipeline from the treatment plant and water bore stations.

The liquefaction study should reveal the extent to which that problem could pose a risk to assets.

The council will then have to think about the extent to which vulnerable assets should be protected or how much money should be spent on that.

- Manawatu Standard

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