On Wed, Nov 15, 2006 at 06:49:16PM +1100, Evan Beaver wrote:
> There seems to be this political grand gesture agenda
> going around at the moment where the government tries to woo us with gifts.
> Parramatta City Council's interest free water tank arrangement isn't quite
> as glamorous as an enormous engineering marvel.
I'm not an engineer but I get to lecture plenty of them. I must say
glamorous isn't an adjective that springs to mind when civil engineering
is mentioned but anyway I thought I'd some arithmetic to see if their
work is overrated.
According to the Herald article Parramatta Council is offering interest
free loans for 5000 litre rainwater tanks which cost roughly $1000.
About 500 people in the Parramatta area have previously taken up Sydney
Water's rebate for rainwater tanks. So if we supose council's offer
persuades 1000 more people to install rainwater that is 5 megalitres of
water storage at a cost of roughly $1 million.
The Tillegra dam is supposed to have a capacity of 450,000 megalitres
at a cost of $350 million. So it'll cost 400x more but hold 100,000x
more water than the Parramatta tanks.
There are other interesting attributes like catchment. I can't see how
to easily calculate these for a lunchtime e-mail but I'm betting you'd
find similar large economies of scale.
Comparing one large environmental impact to many very small impact is much
harder still. I don't doubt this dam will be bad for birds, but what
little I've seen about the site suggests about as little environmental
impact as a large dam in the region could have - no Queensland Lungfish in the
Williams River. But I could be convinced the dam, or the rainwater tanks,
are a bad idea.
Incidentally, the dam is claimed to be carbon neutral, most vegetation
cleared before filling and it'll generate a litle hydro.
I feel more than a little sympathy for the dairy farmers forced off land
that they have held for generations. But as an inner city dweller I
think the accusations of sprawling land use being pointed at Sydney
are unjustified. Clover Moore said yesterday they are planning for
40,000 more people in the next decade living in the sydney city local
government area - basically CBD and surrounds - less than 3000 already
heavily used hectares.
Andrew
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