By KIERAN FINNANE
The popular misconception about sand being taken out of the Todd River is that this is done as a flood mitigation measure, deepening the channel to allow a greater volume of water to flow within the banks. In truth, it would take major works to achieve this, including the removal of causeways and the re-location or re-laying of services that are under the river (such as water, sewerage, and electricity).
The works that are undertaken are better described as “channel improvement” to prevent channel migration and bank scouring.
The Town Council’s Director of Technical Services, Greg Buxton explains why this is done “to ensure the river doesn’t change course and endanger the properties close to the existing river banks.”
The sand won from the works is used at the landfill, mixed with other soils to cover rubbish. This use does not motivate the works, says Mr Buxton. Council’s new management regime at the landfill has reduced the requirement for cover by 65% and it will be further reduced when the new transfer station is built, by the end of 2012 or early 2013. This means that there is more than enough clean fill both stockpiled and coming in from construction sites, in particular from infrastructure works in the town camps, to cater for cover needs for years to come. Having the river sand as part of the mix puts it to use but it could be done without, says Mr Buxton.
Guided by bed level data produced by the Department of Natural Resources, council has completed sand removal from north of the Schwarz Crescent causeway. Works downstream are waiting for Aboriginal Areas Protection Authority (AAPA) approval. As reported earlier this week (see separate article, ‘No shift in council’s priorities in the river’), works at Heavitree Gap are seen as a priority and would contribute to reducing the threat of flooding. “Silt, fines and sand” deposited at the gap by flows have “grassed up” with couch and kikuya, matted into a solid mound (pictured) that now stands well above the Bloomfield drainage line. These conditions could lead to the river breaking its banks in a Q20, let alone a Q100.
Mr Buxton says action to remove this “beaver dam” has been supported by three native title holders who contacted council at the beginning of the year on the matter. AAPA, however, is obliged to consult a wider group of custodians before a certificate can be issued. Mr Buxton says they are working towards a certificate that would allow re-channeling works on an on-going basis to bring the bed back to “a manageable level”.
The Alice Springs News Online asked Mr Buxton why that situation had been allowed to build up to the point that it has. We recalled the extensive works to clear this section of the riverbed of weeds, particularly couch grass, and sand, undertaken in the early 2000s as part of the Alice in 10 Todd and Charles Rivers Project. Why hasn’t there been regular follow-up maintenance?
The Alice in 10 project was before Mr Buxton’s time – he’s been in his current position for four years – but he ‘s also of the view that the work has only become necessary as the result of the rainfall over the last 12 months.
This time 11 years ago we were reporting on the lack of a long term strategy to manage the river for weeds. There’s no sign of this changing anytime soon.
We put to Mr Buxton that council’s management of buffel and couch amounts to no more than a token effort. However, he does not agree that these grasses are “a huge problem”. He says council manages them by slashing in an ongoing six to eight week cycle, with its own crew aided by trusties from the prison. He admits, however, that this effort has been “a bit light on” over the last couple of months as the crew was redirected elsewhere to slash and burn firebreaks, with priority areas identified by the fire service.
He also suggests that management of buffel grass would not have prevented the loss of the last three major trees in the river to burn, as they had been deliberately targeted by arsonists.
He says council could only consider a more intensive weed management program, including spraying, with funding from the government. Council simply does not have the workforce to do a careful spraying program.
Would he push for the necessary funding? He was reluctant to go that far.
Pictured below: Council removing river sand north of Schwarz Crescent in May 2010. Photo by ALEX NELSON.