Media release from Independent arborist 31.10.2011

White cedar trees in William Street Mayfield

INDEPENDENT ARBORIST ASKS HOW NEWCASTLE COUNCIL CAN REMOVE LAMAN STREET’S FIGS BASED ON OPINION RATHER THAN SCIENCE

Background: Mr Craig Hallam is an arborist who works for over 100 Councils both nationally and internationally. He has inspected the Laman Street trees on several occasions. His company ENSPEC does dynamic testing of mature trees.He spoke with Newcastle City Councillors recently about how to manage the trees and this is his statement after seeing the 7:30 NSW/Stateline report from 28th October.

NEWCASTLE GOES THE FULL FIG

NEWCASTLE GOES THE FULL FIG.

I suppose being called to an Art Gallery and library to evacuate people in case of falling trees would have to be a cushy job for workers whose job regularly puts them in harm’s way…

Here’s hoping no one is ever at risk while emergency crews’ time is being wasted in Laman Street.

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Cyber bits and pieces

As usual, I’m still obsessing about risk and the definition of tree failure. I couldn’t stand it any more so I sought (more) advice. I do like to able to argue intelligently with my cyber bullies.

Darby Street Fair 10.10.10

The Darby Street fair was on today, with crowds of people listening to music and eating lovely food in our restaurant strip just around the corner from the Laman Street figs.

I think it’s an annual event, but living nearby I can tell you it feels a lot more frequent than that. What did I read just today? The days drag but the years fly by. Anyway, it was a great spot for a few of us to man a possie/pozzie (how does one spell that?) just outside the pub to ask people to sign our petition. We were up to 6500 in total a week ago so it should  be almost 7000 by now. I wonder what the record is for a Newcastle issue? And still be unsuccessful?

The wind was a bit of a nuisance and it rained every now and again but that’s probably not a bad thing – it must have sent some punters home early instead of encouraging then to keep drinking. Which reminds me that one supporter made the comment that binge drinking leading to violence is a much bigger risk in Newcastle than Our Fig Trees. It’s been a fantastic thing for everyone (except a number of hotel owners) that hotels lock people in and out after 1am now. Violence has dropped impressively. What a shame this hasn’t been an impressive enough trial to convince our state Premier to encourage this elsewhere.

 Talk of risk reminded me of a conversation between a local arborist and Mark Hartley (the experienced arborist who did a peer review for us of the council’s arborist reports). An expert with local knowledge gave Mr Hartley some information regarding the frequency of fig tree failures over a decade or so. These figures make a difference to the ‘probability of failure’ used in quantified tree risk assessment (QTRA).

‘… on page 9 [of your peer review], you conservatively estimated the risk of fig tree failure at 1:500 and I think that is a little out. With the benefit of local knowledge I can state that I have personally witnessed at least 4 entire tree failures in Newcastle over the last 10 years (only Hill’s figs) including the Pasha Bulker storm event, and 2 catastrophic failures of the majority of the canopy that would have been included in the same class because of the size of the part, although the nature of the failure cause was different.  There are 1200 Figs left in Newcastle of a mature size.

So 6 large or complete failures over a 10 year period out of approximately 1200 trees, what would that make the probability of failure? …Would that increase or decrease the outcome of the probability?’

To which Mr Hartley replied:

…Based on your data in 12,000 tree years (10 x 1,200) there have been 6 failures which means a rate of failure has been 1 in 2000. I have estimated the Probability of Failure to be 4 times higher than those records indicate. (…there is some reason to be [conservative] 

 This means that the trees outside the gallery would need to be 20 times more likely to fail than the average fig tree in council’s care. It also means that the least conservative estimate for the probability of failure (PoF) provided by the council’s experts is 20,000% out….

 In addition there is some evidence to suggest that root severance contributed to at least two of the failures. If these are eliminated then the failure rate due to defects alone is 1 in 3,000. Furthermore, the trees outside the gallery have all been assessed as being free from the significant included stem structure that resulted in the two structural failures … whilst limb failure is possible, loss of large portions of the tree is very unlikely.

 If these two structural failures are eliminated then the rate of failure has been 1 in 6,000 This is close to the Probability of Failure of 1 in 5,000 that I said I believe can be achieved with light reduction and thinning.  

 This means that the Laman street trees would need to be 600 times more likely to fail than the average tree without cut roots and significant structural defects in the trunks in order to achieve the Probability of Failure adopted by [one of council’s experts] and 800 times more likely when considering [another].

Isn’t it nice to see written down by experts why you felt so safe under those trees? Home
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You can smell the coal dust today, not just see it 2.10.2010

Years ago I had a friend who loved gliding and he convinced me to go on a joy flight.  I only went once because it was claustrophobic and nauseating but what I did learn from it, apart from the fact that you can have all that space around you and still feel penned in, is that there are Weather Things called Inversions and I assume that’s what we have today.

‘Transition of the space’ 7.9.2010

At left is a picture of a branch that fell off a tree in Civic Park in our CBD during the wild winds on the weekend. Was that a fig tree I hear you ask? No, it was a poplar.

Did Laman Street figs survive this week’s 102km/hr wind? 5.8.2010

This week we had another storm. According to the Herald, ‘Wild weather of Pasha pedigree’ there were wind gusts up to 102km/hour.

The root of the problem

Call me naive but I was a touch surprised to see an image gallery on Newcastle City Council’s website called ‘Fig tree root failures’.

A short version of Mr Marsden’s report on Laman Street

The day when council revisit the issue of the Laman Street Civic Park precinct is fast approaching.