A LONGTIME Tamar estuary researcher believes its silt problem could be solved by redirecting Tailrace flows through a canal on the river’s western side.
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Ian Kidd, who is completing a PhD on estuarine science, has estimated that this waterway could remove 285,000 cubic metres of silt from the Yacht Basin.
Mr Kidd said the plan would address flow issues with the Tamar and would be an alternative to releasing the South Esk River.
“It will get water back into the basin with the added advantage of bringing a huge tidal volume with it,” he said.
He said water in the canal would have been already through the Trevallyn Power Station so it would not reduce its hydroelectric power capacity.
He said the canal would flush silt and pollutants from the upper Tamar and provide a recreational waterbody at the edge of central Launceston.
The solution to pollution is dilution
- Tamar estuary researcher Ian Kidd
Mr Kidd said it would create new expensive riverside property creation and boost the value of existing surrounding property.
He said the canal could be funded through a public and private partnership given the commercial opportunities in and around the estuary that came with a new waterway and silt-free basin.
Mr Kidd said during floods the flow would be reversed within the waterway and drain over a spillway at the Riverside end.
He said flood threats were alleviated by an increased cross-sectional area available to accommodate the flood flow.
The canal proposal to scour silt has been previously been mentioned in the significant 2008 Upper Tamar River Sediment Evaluation Study by BMT.
In the report, it was suggested that a divisional canal could take the water of the North Esk River directly to Stephenson’s Bend.
Fine particles carried by the North and South Esk rivers and mixed with the Tamar's saltwater would continue to cause at least 30,000 cubic metres of sediment a year.
More than 100,000 cubic metres has steadily built up in the Yacht Basin in the last year following silt raking and three minor releases from the Trevallyn Dam in August.
TasWater proposal to reduce their impact on water pollution and sedimentation build-up in the Tamar involves building a new $285 million secondary treatment plant at Ti Tree Bend.
Mr Kidd said to be effective, the plant would need to be positioned more than 10 kilometres down the river near Rosevears or Legana where the tidal volume was higher.
“The solution to pollution is dilution,” he said.