Where’s the stormwater going to go? 22.8.2010


Today feels like spring – unlike yesterday when an icy wind blew on us as we stood in the queue to vote. What a bizarre election result so far.

Laman Street is looking at its best today – if you squint to avoid seeing the stupid roadwork barriers some eejit has decided are necessary to continue to convince the punters that council have their best interests at heart.

I had to share with you a great interview I read with one of the architects of our urban forest policy – part of the same team that brought you a vision of liquidambers (see last post). It’s from a newsletter from ‘Terracottem’ which would appear to be a growing medium for plants. The interview leaves me speechless. A great picture taken in Laman Street under the fig trees accompanies the article – but  I defy anyone to take a bad photo in that street. The article comes from


‘Just when you think Phil Hewett’s soap-box rave threatens to take off into the realm of fanatical, he comes good with the facts, the science and a brutally clear assessment of human kind, and you’re gasping. He knows his stuff, and what makes his rant so good is that his special topic is something we already understand because it’s all around us – or, according to him, it should be.

We’re talking about trees, and we’re listening to Phil* describe the way they should be thought about and managed in the urban setting. “We must have an intuitive sense of their value because, after all, people plant trees. But limited surveys also show we have a split view – that in working class suburbs many people view trees as a nuisance where in other areas of wealth and education it’s the opposite.”

The truth is, the tree lovers are right. “Trees improve air quality, help to conserve energy, reduce storm water, improve social amenity and support commercial reinvigoration – and there’s good research to support all of these claims.”

Despite that, for 25 odd years of Phil’s working life he’s seen a dysfunctional approach taken to the way our trees are managed and he developed a distrust of local government as a result. “It’s always a case of, I just need to get rid of that tree – picked off for a driveway, blocking pipes, being in the way of utilities, or for the ‘mess’ it generates. But together these trees come down in their thousands and are rarely replaced with something equivalent.

It can take 20 years and a lot of effort to get back what was removed especially as space limitations and liability concerns dictate ever smaller trees which simply can’t reinstate lost benefits. Large growing trees are from eight to twenty times better at dealing with storm water and air quality than small trees.”

Despite this scenario, Phil is upbeat and with good reason. At last there is growing recognition for the fact that trees collectively do a job and therefore that the collective urban canopy has value. The first signs were an environmental levy which has funded Phil’s role as Coordinator, Newcastle Urban Forest Project with the City of Newcastle. Instead of continuing to manage trees in terms of numbers planted each year and percentage lost, Phil’s aim is to develop a long term strategic plan to get on with the business of managing an urban forest – “a plan that’s rational, reasonable, fits the books and adds to the sustainable life of the city.” In practice it’s all about maintaining and improving upon canopy density within the City. Since Council adopted the Urban Forest Policy, everyone has a role in building this – from development planners, engineering, maintenance, construction to greening and bushland management. But there is still work to do on the strategies, with one gaping hole in particular: how do you measure and quantify the value of this urban forest?

“We’re looking to the United States where 30 billion dollars’ worth of research with both agricultural and forestry support has produced some useful tools. We’ll need to adapt these to work under Australian conditions so that we can feed in the information about the canopy and get data on its values.”

The timing is good to build public support given the current focus on sustainable themes. “We’re a selfish society which expects instant gratification.

Eighty years ago people planted trees for our benefit. We need to recognise that and plant something to be part of a continuing cycle.”

*Phil Hewett is City Arborist with the City of Newcastle, one of the many councils around Australia which specifies TerraCottem as part of its street tree planting program.

Just one large mature tree intercepts 10,000L rainfall per annum. If you take one of Newcastle’s mature figs it’s been working solidly for the past 60 years and, according to Phil Hewett, the amount of stormwater it’s processed during that time is 600,000 litres. And since there are actually 456 mature figs hard at work in this particular urban fig forest, Newcastle’s built stormwater management system hasn’t had to deal with 273 megalitres of rainwater.’     Home


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2 Responses to “Where’s the stormwater going to go? 22.8.2010”

  1. Ali Says:

    Exactly “SPEECHLESS”!

  2. Ali Says:


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