‘No swimming’ health alert could extend for a week in some sections of the River Derwent
FREE: Parts of the River Derwent could be shut off to swimmers beyond Boxing Day after a sewage leak.
It could take up to a week for authorities to stop partially treated sewage from flowing into the River Derwent at Berriedale, meaning a number of popular beaches across the Greater Hobart area may be off-limits for swimming until after Boxing Day.
On a sunny first day of holidays for Tasmanian state school students, numerous ‘do not swim’ notices were posted at beaches ranging from Austins Ferry and Old Beach in the north and Sandy Bay and Howrah in the south.
It came after high-strength trade waste discharged from Mondelez International’s Cadbury chocolate factory at Claremont effectively forced the Cameron Bay Sewage Treatment Plant at Berriedale offline, due to a “big spike of sugar” disrupting the biological processes TasWater uses to treat wastewater.
The Department of Health is warning people against swimming in parts of the Derwent, saying it could pose a risk to human health through the spread of viruses and bacteria, such as gastroenteritis.
TasWater general manager of customer and community Matt Balfe said the water and sewage utility had been aware of issues with Mondelez’s wastewater treatment processes for three weeks but it wasn’t until 6.30pm on Thursday evening that the bacteria used to “eat the sewage” at Cameron Bay began to “die off” as a result of exposure to the trade waste.
“We’re really disappointed that this has happened at a time in the year when families are gathering around the foreshore of the Derwent, particularly the week that children are leaving school,” Mr Balfe told reporters on Friday.
“We’re working hand-in-glove with both the Environment Protection Authority (EPA) and the Department of Health to make sure we get the plant back online as soon as possible.”
Mr Balfe said TasWater “started to notice more bugs dying off” on Wednesday before “we really hit critical mass” on Thursday night.
He said it could take “a couple of days to a week” for the plant to be “reseeded”, enabling safe levels of effluent to be discharged into the river.
Mondelez has been directed to stop sending trade waste to the Cameron Bay plant for the time being and Mr Balfe did not rule out the possibility of TasWater seeking to impose penalties on the multinational company.
The EPA is working with Mondelez to determine the best option for storing or safely discharging its trade waste.
A Mondelez spokeswoman said the company had recently commenced a $3m upgrade of its own wastewater treatment plant at Claremont, which prepares milk solids and other manufacturing by-products “for safe disposal”.
“We are working vigorously and collaboratively with TasWater to fully investigate and resolve the matter,” she said.
Cameron Bay is a small plant that treats about 4500 kilolitres of wastewater per day during dry weather.
Public Health director Dr Mark Veitch said the Department of Health was advising people to “avoid activities” such as swimming in affected parts of the Derwent until the issues at the treatment plant were addressed.
“We know that the main recreational areas where people swim in the Derwent are well downstream of where this incident is, but it’s our view that until we get some information from further testing of the popular recreational sites, we should provide quite conservative advice for people to avoid swimming in that stretch of the Derwent,” he said.
Dr Veitch said once the plant was fully functional again, beaches should be safe to swim at once more.
“I think we can take some comfort that the highest risk is probably closest to the point of discharge and that people who have spent time swimming the last day or so in parts of the Derwent that are quite a long way away from the point of discharge … their likelihood of getting sick is pretty small,” he said.
Premier Jeremy Rockliff said the state government had met with Mondelez representatives on Friday and was “working very closely with everyone involved in the situation to have it resolved as quickly as possible”.
“Our focus, and my focus … will clearly be on resolving the situation so people can enjoy their beaches and their recreation as soon as possible,” he said.
Glenorchy Mayor Sue Hickey said the council was conducting its own water sampling in response to the Mondelez situation.
“Obviously any incident which causes areas to be closed for swimming and recreational use is a concern, and we’ll await further advice from TasWater and other relevant agencies as the situation hopefully resolves as quickly as possible,” she said.
Greens water spokeswoman Helen Burnet called on Mondelez to apologise to the Tasmanian community, saying it had committed “a breach that should not have happened”.
“Clearly, there has to be better standards and better responsibilities by companies such as Mondelez International, and it’ll be incumbent on both TasWater and the EPA to ensure that there are higher standards,” she said.
Originally published as ‘No swimming’ health alert could extend for a week in some sections of the River Derwent
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