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| NUMBERS CRUNCHED: John Hodgkinson (left) and Trevor Herse's solution could have averted the destruction of the 1974 and 2011 floods. |
IT HAS taken some serious number-crunching but a humble accountant, a retiree and an Imbil grazier have come up with a plan to flood and drought proof Brisbane.
After analysing flood volumes and rainfall figures as far back as 1893, accountant John Hodgkinson, Gold Coast retiree Trevor Herse and grazier Ron McMah believe the secret to safeguarding the southeast lies high in the Mary Valley.
They want the little-known Borumba Dam near Imbil connected by pipeline to Wivenhoe and Somerset and expanded into a mega-facility capable of holding two million mega-litres - four times the volume of Sydney Harbour.
As well as flood-proofing Brisbane, the scheme could also protect Ipswich and Gympie.
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| FLOODED: Aerial photo of part of Brisbane flooded in 2011. |
Two years from the day the 2011 floods damaged 20,000 properties in Brisbane and Ipswich, the Newman Government has been urged to consider their bold plan and is starting to show some interest.
Mr Hodgkinson said the idea was hatched during the fight to stop Traveston Dam and the trio had worked on it ever since.
The Bligh Government had previously studied the bid as an alternative to Traveston but rejected it on "financial and environmental grounds".
But Mr Hodgkinson believes it was rejected solely for political reasons in favour of Traveston and the Tugun desalination plant.
"The integration would have a dual purpose. Water could be pumped to Borumba from Wivenhoe and Somerset before a major flood and in times of drought, it could be pumped back," Mr Hodgkinson said. "We believe it would secure our future."
The beauty of the plan lies in its simplicity.
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| Wivenhoe Dam. |
A pipeline running 60km from Wivenhoe to an expanded Borumba could pump water up at the start of a La Nina wet season or when the catchment is saturated - just like it was just before the 2011 floods.
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This would allow Wivenhoe to drop to near zero per cent, effectively doubling its capacity to handle a flood. Somerset would be reduced to just 380,000 megalitres - the level of its drinking water compartment.
With these reductions, the two dams would be able to hold 3.1 million megalitres in a flood.
"With Wivenhoe at zero and Somerset reduced, you could easily handle even the 1893 flood - and it is our biggest on record," he said.
With the two dams holding back run-off from even an unusually high rain event in the catchment, it would also alter the impacts of flooding rain below the dam walls.
The Lockyer Creek and Bremer River below the dams could flow freely, mitigating floods in Ipswich.
Mr Hodgkinson said the project would take three years to complete. Engineers who built Wivenhoe have costed the project at $1.9 billion - $1.4 billion for a new 85m high dam wall including a hydro plant and $500 million for the pipeline.
"This is cost-effective when you consider one desalination plant costs $1.5 billion," he said.
Pumping could be done at night when there is ample power available on the grid at almost no cost.
As the dam already exists, there would be no displacement of people as the state owned some of the land near Borumba, while much of the remainder included national park.
Mr Hodgkinson said the proposal would also remove the dilemma faced by the Government at the start of each season about whether the Wivenhoe dam level should be dropped from 100 to 75 per cent to allow for more flood-absorbing capacity.
"Cabinet making the decision to drop the dams by 25 per cent is a serious decision," he said.
"If they're wrong the water is wasted."
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A spokeswoman for the Department of Energy and Water Supply said the Borumba Dam proposal had been raised with officers of the now-defunct Queensland Water Commission in 2008.
"In August 2011, the QWC wrote to Mr Hodgkinson rejecting the proposal on financial and environmental grounds," she said.
But since the Newman Government came to power, Mr Hodgkinson said the proposal had gained renewed interest and hoped it will be included in future plans.
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| LIKES SOLUTION: John Craigie at his house at Pine Mountain which flooded in January 2011 during the Brisbane Floods. |
The idea also has flood victims interested, including Pine Mountain nurseryman John Craigie, whose house was submerged in 2011 despite being on a cliff 26m above the Brisbane River.
Mr Craigie said he welcomed any new ideas on how to improve flood mitigation in the catchment.
"I think something like that does have to happen," he said.
"The flood storage capacity of Wivenhoe Dam needs to be re-examined to see if it's adequate."
Build a 60km pipleine to connect Wivenhoe and the Borumba Dam, 11km from Imbil
At the start of a La Nina wet season or when the catchment is saturated, water from Wivenhoe and Somerset could be pumped up to Borumba
With Wivenhoe near zero and Somerset reduced, flood storage capacity would be doubled
After the wet season or in times of drought, water could be pumped back down to Wivenhoe
BY THE NUMBERS
- 60 kilometres: Distance of a new pipeline built from Wivenhoe to Borumba Dam
- 85m: The additional height of the dam wall at Borumba
- $1.4b: For the new high dam wall
- $500m: For the Wivenhoe to Borumba pipeline
- $1.9b: Total cost of the project, as assessed by engineers who built Wivenhoe
- 3 years: Amount of time to build pipeline and new dam wall
- 2m: Megalitre capacity of an expanded Borumba
- 20,000: Properties damaged in Brisbane and Ipswich in the 2011 flood
13.1.13
COMMENT: This proposal is a sensible way forward for the future flood-proofing of Brisbane, Ipswich and possibly Gympie. It is financially achievable given the huge benefits it would produce for southeast Queensland. It cannot be simply dismissed by bureaucrats in Seqwater whose idea for the future is thinking about knock-off time. If Campbell Newman wants to leave his mark as the "Can Do" Premier of Queensland, he could do a lot worse than to review the feasibility of this plan with a view to its early implementation. - PaulGTully@gmail.com
