Tonkin & Taylor: Canterbury Land Information
Latest News
There is strong media interest in Tonkin & Taylor's Canterbury Land Damage Assessment Team.
24/06/2011 - YouTube: Tonkin & Taylor - Land damage in Christchurch's residential red zone
Nick Rogers from Tonkin & Taylor talks about the earthquake land damage in Christchurch's residential red zone and what it would take to repair it.…
Television Coverage
17/04/2012 - 3news.co.nz
QEII quake test simulates 7.5 mag shake
Building foundations on liquefaction prone land have been put through a simulated 7.5 magnitude quake at Christchurch’s QEII stadium. Tonkin & Taylor’s Peter Millar has been leading the ground testing for the Earthquake Commission (EQC).
13/12/2011 - tvnz.co.nz
Central Christchurch land can be rebuilt on - engineers
All land within Christchurch's Central City can be rebuilt on, says the geotechnical report by engineering consultants Tonkin & Taylor.
The Geological Interpretative Report, part of the final draft Central City Plan which will be adopted by the City Council this Thursday, says: “No areas within the CBD or adjacent commercial areas were identified as having ground conditions that would preclude rebuilding on those sites”.
However, the report does say that “more robust foundation design and/or ground improvement may be required”.
Read the whole report and watch the video here »
13/12/2011 - 3news.co.nz
Relief and excitement after CBD rebuild cleared
But Mayor Bob Parker says the Tonkin and Taylor report saying the city can be rebuilt will help change minds.
“The great news is, yes, we can build the city here,” he says.
Read the whole report and watch the video here »
01/11/2011 - 3news.co.nz
ChCh residents not pleased with simulated quakes
Explosives have been used to simulate an earthquake in Christchurch’s already battered eastern suburbs.
The locals are not too happy about it but the Department of Building and Housing says it is testing different types of foundations for homes in areas prone to liquefaction.
QE2 stadium was shaken by another large earthquake today, but this time it was caused by 50 kilograms of explosives.
“What we are doing is testing a number of foundation options that can be used as generic solutions for repair of properties which have been damaged by liquefaction in the Christchurch region,” says geotechnical engineer Peter Millar.
Read the whole report and watch the video here »
01/11/2011 - tvnz.co.nz
Chch residents unimpressed by quake simulation
Some Christchurch residents are furious after an underground explosion simulating a magnitude 4 earthquake was allowed to go ahead in their area.
Fifty kilograms of ammonium nitrate gel was placed six metres underground then detonated in order to test four new building foundation models built beneath the surface of QEII Stadium, and how they will stand up to a large scale shake.
Engineers then tested the water pressure under each of the different foundations to see how the land reacted. “We are going to have these generic solutions out of this - that will provide people with confidence in terms of what kind of foundations they can have,” said Peter Millar from Tonkin and Taylor.
Read the whole report and watch the video here »
05/09/2011 - 3news.co.nz
Christchurch hill suburb residents told land is safe
More than 9000 homeowners in Christchurch's hill suburbs have been given the green light to begin repairing or rebuilding their earthquake damaged homes.
Tonkin & Taylor's Senior Engineering Geologist Kate Williams is interviewed here »
23/06/2011 - tvnz.co.nz and 3news.co.nz
Prime Minister John Key announces the Government's plans for Christchurch's worst hit suburbs on 23 June 2011
Watch the announcement here (tvnz.co.nz) and here (3news.co.nz) »
Radio Coverage
14/12/2011 - Radio New Zealand: Morning Report
The decision that rebuilding in Christchurch's central city can go ahead is reassuring business leaders the central business district will regenerate. The Christchurch City Council has just released a geotechnical report by the engineering consultants Tonkin and Taylor, which says there are no areas within the CBD which can't be built on.
Listen to the audio here (MP3 1.1mb - Duration 3min 20sec.) »
And here (MP3 2.2mb - Duration 6min 22sec.) »
06/09/2011 - Radio New Zealand: Checkpoint
Tonkin & Taylor's Senior Engineering Geologist Kate Williams is interviewed for Checkpoint - Tonkin & Taylor's work in the orange zones of Canterbury. Duration 4min 05sec.
Listen to the audio here (MP3 1.4mb) »
05/09/2011 - Radio New Zealand: Morning Report
Tonkin & Taylor's Managing Director Doug Johnson is interviewed on Morning Report - Tonkin & Taylor's work in Canterbury since 4 September 2010. Duration 2min 58sec.
Listen to the audio here (MP3 1mb) »
24/06/2011 - Radio New Zealand: Nine to Noon
Nick Rogers, project director, Canterbury Land Assessment for Tonkin & Taylor. Tonkin & Taylor is the environmental and engineering consultancy doing the Canterbury land damage assessment work for EQC and the Canterbury Earthquake Recovery Authority. Duration 14min 03sec.
Listen to the audio here (MP3 4.8mb) »
Print Articles
13/12/2011 - stuff.co.nz: Central city cleared for rebuild
All the land in central Christchurch has been declared suitable for building on despite the threat of further earthquake-generated liquefaction, a geotechnical report released today says.
The Tonkin & Taylor Geological Interpretative Report out today concludes that “no areas within the CBD or adjacent commercial areas were identified as having ground conditions that would preclude rebuilding on those sites, although more robust foundation design and/or ground improvement may be required”.
Adopting the proposed minimum 30-metre setback from the Avon River would “likely preclude the worst-affected areas from future development”.
13/12/2011 - nzherald.co.nz: Christchurch CBD land can be rebuilt on - report
All of the land in Christchurch's central city has been cleared for rebuilding on, although some areas may require more foundation or ground work.
After months of uncertainty, the geotechnical report by engineering consultants Tonkin & Taylor says “no areas within the CBD or adjacent commercial areas were identified as having ground conditions that would preclude rebuilding on those sites”.
The report - which is part of the final draft Central City Plan which will be adopted by the Christchurch Council tomorrow - does point out that “more robust foundation design and/or ground improvement may be required”.
But Christchurch Mayor Bob Parker has applauded the timing of the report, saying it would give land and property owners much more certainty and confidence, know that they knew their sites were suitable for rebuilding.
01/11/2011 - stuff.co.nz: Fake shake tests foundations and patience
An explosive-generated shake yielded mixed results for a government field trial in Christchurch while residents are asking why it was conducted at a crippled stadium that might be repairable.
The Building and Housing Department yesterday used about 50 kilograms of explosives at Queen Elizabeth II Park to simulate a magnitude-4 earthquake, at a distance of 10 kilometres.
The blasts were used to induce liquefaction below the turf of the stadium's 400-metre running track, to test soil-strengthening techniques that could be used to repair land.
Tonkin & Taylor geotechnical engineer Peter Millar said the explosives, which were buried 4m to 6m deep, produced an acceptable level of energy but there was less liquefaction than expected.
Read the whole story and watch the video here »
25/07/2011 - stuff.co.nz: Orange zone puts futures on hold
Mike Jacka, a principal and geotechnical engineer at the commission's consultant engineers Tonkin & Taylor, says it is a massive job and there is immense pressure to get it completed quickly.
“Certainly, we understand that people in these orange zones want resolution as quickly as they can so they can move on,” Jacka says.
“But we still make the right decision - you can't make this decision twice; you only get one shot.”
24/06/2011 - stuff.co.nz: Don't stop now, says Brownlee
At yesterday's announcement, Tonkin & Taylor geotechnical specialist Nick Rogers said the February 22 quake had caused huge problems for the land investigations.
“It wasn't one step forward and one step back; it was more like one step forward and 10 steps back.”
He outlined the engineering research on which the Government based its decisions.
Surveying of benchmarks by Land Information New Zealand after the September quake showed Christchurch had rotated clockwise, a motion pronounced in the western half of the city.
After the February quake, the benchmarks showed the city had moved southeast, with large vertical movement, some parts dropping down and other parts rising.
23/06/2011 - stuff.co.nz: Crown to buy 5100 quake-hit Christchurch homes
'WONKY' CITY
The liquefaction damage was unprecedented around the world, Tonkin & Taylor engineers technical expert Nick Rogers said.
He said things looked “wonky” all around the city.
Rogers said there had been a lot of ground settlement, reducing the thickness of the crust between the surface and the ground water table.
It made liquefaction worse and made it harder for the ground to support buildings.
Some areas had suffered a shift, with a clockwise trend around the city in September, but in February land had sunk though in areas such as the Port Hills land had risen.
14/06/2011 - stuff.co.nz: John Key press conference
John Key holds a press conference after being briefed by mayor Bob Parker, earthquake recovery boss Roger Sutton, Earthquake Recovery Minister Gerry Brownlee and engineers from Tonkin and Taylor.
16/04/2011 - stuff.co.nz: Can we fix it?
So first must come the science. A research effort of a scale probably unique in New Zealand's history reckon those involved, like Kate Williams, senior engineering geologist for consultants Tonkin and Taylor.
As the Earthquake Commission's (EQC) lead engineer, Tonkin and Taylor has become a familiar name. After the September earthquake, it had already delivered the first two stages of its geotechnical report - the good news that almost all the land could be fixed with a mix of stone column “earthdams”' along river edges, good drainage, and machine compaction of liquefied soils.
A third and final report was within weeks of being made public when the February 22 earthquake struck. Now, it is back to the drawing board, start all over again, says Williams.
There is an advantage in that the firm has built up its numbers in Christchurch. It employs some 280 engineers doing EQC property assessments alone. “Following the second quake, all the systems had been developed, a process had been ingrained in our teams, so people could be sent out straight away,” says Williams.
However, the scale of the damage is many times greater now. And more agencies have had to get involved as some completely new issues have arisen.
Bodies are being thrown at the work, says Williams. Science that would normally take months, if not years, is being crammed into weeks because everyone realises the land remediation question is what is going to hold up the whole recovery process. It is pointless fixing sewers or sending in builders until it is known whether the houses can stay.
Williams says the Government is expecting its first report from Tonkin and Taylor by mid-May. So far, only 30 per cent of the necessary information is in. Yet, she believes the report can be complete enough to allow some larger decisions to be made by June.
“We're not going to go to 100 per cent by then - though you know, as scientists, we'd love to be before we give any recommendations. But there has to be a point in time where we say we have enough information that is robust.
“So by around mid-May, we may be able to inform people, not on individual properties, but probably on a suburb or street-by- street basis, about what may happen in their neighbourhoods.”
Williams says the damage story is complex and cannot be prejudged. Prime Minister John Key has already indicated bad news. At a post-Cabinet briefing in early March, he said there will be some areas that won't be rebuilt on: “There will be parts of Christchurch where the option is simply to take a cheque or say 'here is a subdivision, you can choose a site and a building plan'.”
But Williams says no-one wants to alarm people with partial information. And the numbers that may have to move is still very unclear.
One of the reasons for uncertainty is a new factor to be considered after February 22. That of flood risk. The shaking and liquefaction was so bad, some suburbs may have sunk by a good metre.
All that grey silt which boiled up out of the ground and got carted away - Fulton Hogan shifting 32,000 truck-loads in a fortnight - has left the land lower.
And then whole slabs of Christchurch may have been dropped or tilted because of the way the fault disturbed the ground.
An early survey by the government research institute, GNS Science, found that the Port Hills had been lifted 40 centimetres higher by the quake, while the Avon-Heathcote estuary had been shunted sideways by some tens of centimetres and may have fallen by a similar amount as well.
Williams says Land Information New Zealand (Linz) is responsible for mapping the new level of the city. Linz researchers have already flown over Christchurch, bouncing a laser off the ground to take accurate readings. But crunching the terabytes of data is another one of those normally multi-year projects being squeezed into a matter of months, she says.
Yet the information is crucial because suburbs along the lower Avon especially, like Bexley, New Brighton, Avondale and Horseshoe Lake, could now be far more prone to spring tides and storm surges.
The council had to sandbag danger areas ahead of the spring tides last month. “A metre makes a big difference,” says Williams.
In assessing the flood risk, there is the further complication of Variation 48, a recent rule change to the council's city plan brought in to deal with climate change and expected sea-level rises.
The variation means all new buildings in low-lying parts of town have to raise their floors to a level high enough to cope with once-in-200-year floods. So when it comes to any post-quake rebuilding in these areas, this becomes another expense to be added to the land repair balance sheet.
Williams says there is always an engineering solution to any problem. Homes can be put on stilts, land can be filled, dykes or stopbanks can be constructed to keep the sea and floods out. But then there is the cost. At some point, it makes more sense to shift instead.
Williams would not be drawn, but others are looking at suburbs like Bexley and wondering if there is any choice besides an orderly retreat before the tides eventually reclaim such areas as part of the estuary wetlands.
The big question, of course, is still the issue of liquefaction and lateral spreading.