By Amanda Morrall
Liquefaction, now part of the daily vernacular in Christchurch, is proving to be a major obstacle to insurers trying to process tens of thousands of claims.
Before insurers can begin pay-outs for repairs and rebuilds on land compromised by one or both earthquakes, the long-term security of the ground underneath needs to be established.
At least 10 neighborhoods in Christchurch have suffered liquefaction, representing roughly 25% of insurance claims for building damage, according to one Christchurch insurer.
Aranui, Avonside, Avondale, Bexley, Burwood, Dallington, Richmond, Shirley, Wainoni and Phillipstown are among the most severely land damaged communities. Hillside neighbourhoods in the Eastern suburbs face equally disasterous and costly damage from land shifting and crumbling cliffs. (See financial columnist Janine Starks article here on cures for quake stress).
There are three main ways to reduce the effects of liquefaction: by stabilising the ground, by specific foundation design or by strengthening structures to resist predicted ground movements.
Waimakariri District Council, facing a similar but smaller scale problem after the September 4 earthquake, came up with a plan to rebuild neighborhoods damaged by liquefaction in an coordinated targeted manner to avoid builders, insurers, EQC, power companies working at cross purposes. (For rebuilding time frames in the area click here). For frequently asked questions, click here.
The plan, which involves the participation of 15 parties, maps out the sequence of repairs, explains in simple terms how they'll be done and by whom, and justifies the rationale for tackling problems in the order specified by engineers.
A proposal to do something similar in Christchurch is garnering some attention and was the subject of a wider discussion on Monday at Lincoln University on how to rebuild the badly damaged city.
Simon Markham, earthquake recovery manager for Waimakari District Council, said having a plan that identified what steps would be taken and when was a comfort to residents, many of whom wouldn't be returning to their homes for two years.
No public consultation
Although the plan itself was developed without public consultation, Markham said residents have so far been receptive. A series or community meetings, originally scheduled for February 22, has recently got underway to inform.
"The feedback on balance has been good. At least now they have some indication of timing from a situation of not knowing anything. So now we have a sense that it's a three-year plus programme and some of the areas are going to take a lot longer than others. Obviously the hardest part is for those people who are not due for remediation and repair until 2013.''
Markham said Christchurch may benefit from a similar approach when it emerged from the response phase of the February 22 earthquake.
"We've had some time to sit down and think about how to do the rebuild as part of the recovery but they're still working at the response stage.
"We had that for a period after September 4 then came up for air about mid October and that was intensive and comparable, but nowhere near on the same scale.''
By one estimate, the Christchurch rebuild will cost NZ$30 billion.
Fixes to land damaged by liquefaction are neither quick or cheap. (For a map of zones deemed at risk of liquefaction and a primer on fault lines in Christchurch and land remediation processes see this fact sheet by Environment Canterbury.)
Rates in Waimakariri are going up by 6-8% on average with some households facing increases of 14% to cover the cost of a new waste water treatment facility.
Christchurch City Council, while offering rate subsidies for its hardest hit residents from September 4, is currently reviewing the situation.
Meanwhile, insurers are warning residents both in and outside of Christchurch to prepare for premium hikes of a minimum of 20% in coming months as they work to recover their losses from the back to back earthquakes and pay for substantial reinsurance costs. (See story by Amanda Morrall here).
See eqviewer.co.nz for more information on earthquake facilities and mapping of damaged areas.