To Paradise and beyond - Page 2
From Griffith REVIEW Edition 20: Cities on the Edge
© Copyright Griffith University & the author.
Written by Peter Meredith
WITH DAVE MURRAY BESIDE ME in my hire-car, I let a torrent of traffic carry me through Brisbane's western suburbs. An hour later we emerged into a tired landscape the colour of dust.
Murray's mission was to show me dams and tell me about dam building. The deal was that we'd avoid politics. He acknowledged there were issues with large dams that dam-builders needed to come to terms with. But dam building is his life, and he is passionate about his work and does it to the best of his ability. I have no problem with that.
The first dam on our itinerary was Wivenhoe, on the Brisbane River, forty kilometres west of the state capital. It consists of an earth and rock embankment more than two kilometres long and fifty metres high and a concrete spillway topped by five steel gates. As well as providing water and generating 4.5 megawatts of electricity, it was designed to prevent flooding in the city. Floods seemed an incongruous notion that day; twenty-two years after the dam was completed, Lake Wivenhoe was just 15 per cent full.
Wivenhoe Dam does its job well. If there are good dams and bad dams, if a dam's minuses don't swamp the pluses across a spectrum of (usually anthropocentric) criteria, this is probably a good one. Generally, bigger dams are more likely to be ‘bad'. But not all small dams are ‘good', and even ‘good' dams have negative impacts. Wivenhoe's include a litany of upstream and downstream effects: major changes to habitats for invertebrates and fish in the Brisbane River and detrimental impacts on fisheries in Moreton Bay. On the other hand, without it Brisbanites wouldn't be able to flush toilets or have showers, and would live in fear of floods.
Murray helped build Wivenhoe. The son of a travelling movie salesman, he was born in Brisbane, raised in Townsville and excelled at maths at school. In 1975 he graduated from the University of Queensland with an honours degree in civil engineering and joined the Water Resources Commission, which seconded him to the Wivenhoe project. One of his tasks was to lay the foundation grouting, the mixture of cement and water that would waterproof the rock foundation.
Next we visited Borumba Dam, on Yabba Creek a hundred kilometres further north. This is arguably another ‘good' dam. Finished in 1964, it supplies water to irrigators and the Sunshine Coast via the Mary River and is popular for fishing and boating. Lying in a deep valley and with a reservoir that covers only five hundred hectares, it has a relatively small footprint. Under the Water Grid plan, it will be raised to deliver 40,000 ML more a year.
Murray has a soft spot for Borumba. In the 1990s he was in charge of replacing the dam's old spillway, a job requiring speed and dynamite. ‘It's one of my pride and joys,' he said as we contemplated the dam's soot-black concrete. Borumba is a rock-filled embankment 343 metres long and forty-two metres high, with a concrete face on the upstream side and a wide walkway on top. It has all the charm of an urban railway embankment.
Another dam on Murray's pride-and-joy list is Burdekin Falls, south of Townsville, which was completed in 1987. He helped design it and then project-managed its construction, acquiring a master's degree in engineering science along the way. ‘It's hard not to be proud of Burdekin Falls,' he says. ‘It's hard not to say, "Hey, there I was at a little over thirty, building the biggest water supply dam we're ever likely to have in the state!"'
PARADISE DAM, 260 KILOMETRES north of Brisbane, slashes into the Burnett River valley like a colossal surgical instrument. It combines austere curves with scalpel-edged lines and brutal angles. On the upstream side, the wall is vertical; on the downstream side it angles down in myriad steps, like those of the Great Pyramid. Its overwhelming mass makes it both beautiful and terrifying.
Paradise is Australia's newest large dam. Completed in 2005, it cost Burnett Water Pty Ltd $200 million. At the time, Burnett Water was headed by Graeme Newton and staffed by a number of other people who've moved on to QWI. Dave Murray was an adviser to the project. He's understandably proud of the end product as a piece of engineering. It never fails to impress, one way or another.
Paradise's spillway stands thirty-seven metres above the streambed and the wall is 920 metres long. When full, it will hold back 300,000 ML of water (more than half of Sydney Harbour's 562,000 ML) and create a three thousand hectare lake forty-five kilometres long.
Murray and I stood on the blinding concrete of the wall-top roadway with a wiry, outgoing bloke named Andrew Maughan. Paradise's service supervisor, Maughan has worked for SunWater, the dam's operator, for twenty years. An awkward gantry loomed above us. This, Maughan explained, was part of the dam's five to eight million dollar fish migration system intended to help the river's aquatic creatures negotiate the vast impediment.
The dam's ingredients include four hundred thousand cubic metres of roller compacted concrete, forty thousand cubic metres of conventional concrete and a million tonnes of crushed rock. This is Australia's biggest compacted concrete dam. Unlike conventional concrete, which needs up to five days to set, roller compacted concrete is laid in thirty centimetre layers in a non-stop operation. ‘It's like a road base, a drier mix,' Murray told me. ‘Each layer is compacted with small rollers so that it bonds with the layer below. When you've finished rolling one, you put the next one down.'
The fish migration system is designed to move fish both upstream and down. Created with input from biologists, it's an ingenious set-up, as I saw when Maughan showed us the system on a computer screen in a control room. If its efficacy can match his enthusiasm, it may well meet the needs of the river's residents.
When he officially opened the dam in December 2005, Beattie declared it ‘raised the bar for environmental construction of dams and land rehabilitation in Australia'. The press release on the event was headed: ‘Paradise regained for the environment with dam construction'. But the weather has been hard on Paradise. At the time of our visit, the reservoir was 9.5 per cent full (though it was up to 45 per cent by early 2008). The computer screen showed a mere three to four megalitres of water a day exiting downstream, hardly enough to operate the fishway or run the 2.6 MW mini-hydro plant.
Despite the former premier's enthusiasm, the dam has attracted a torrent of criticism. A big gripe is that the decision to build it was politically based. Even though the Queensland Government had previously dismissed a dam on the Burnett River as uneconomic, Beattie made it an election promise to counter a National Party pledge to build it. After Labor's 2001 victory, allegations of lack of transparency and whispers about the suppression of a study by the Institute of Sustainable Futures at the University of Technology, Sydney that detailed cheaper and equally effective alternatives to the dam gained widespread currency.
Potential impacts downstream, especially around the river's mouth at the northern end of Hervey Bay, worry commercial and recreational fishers and tourism operators. An international World Wide Fund for Nature (WWF) report in 2005 blacklisted Paradise Dam and five other dams around the world. The report said the Paradise project had failed to meet World Commission on Dams (WCD) guidelines on gaining public acceptance, sustaining rivers and livelihoods and assessing alternatives.
In 2007 a Senate committee inquiring into the Traveston Crossing Dam proposal expressed concern that ‘mitigation strategies for endangered species do not appear to have been effectively implemented' at Paradise Dam. In February 2008 a study by federal environment minister Peter Garrett's department cast further doubt on the fishway's effectiveness. It said ‘findings indicated only partial compliance with a key condition requiring a fish transfer device (fishway) to facilitate passage for the Queensland lungfish downstream past the dam wall ... The fishway cannot presently facilitate the transfer of lungfish downstream due to drought conditions and low dam levels.'
Little about Paradise Dam has galvanised public opinion more than the plight of the endangered Australian, or Queensland, lungfish. One of the last of a group that lived four hundred million years ago, it uses its single lung to supplement oxygen from its gills when stressed. Once abundant across the continent, it's now confined almost entirely to the Burnett, Mary and Brisbane Rivers.
The dam's fishway was installed to comply with the Commonwealth's Environment Protection and Biodiversity Conservation Act, which lists the lungfish as endangered. Scientists believe Paradise Dam has had, and will have, serious consequences for the lungfish. Jean Joss, Professor of Biology at Sydney's Macquarie University, noted that lungfish spawned in slow-flowing shallows with plenty of weed and that under the Act the fish's spawning and nursery habitat must not be destroyed. ‘This has not been addressed at all ... It is exactly these features that are lost entirely by permanent flooding resulting from the construction of dam walls. When it is full, it will have permanently destroyed forty-two kilometres of lungfish spawning/nursery grounds.'