Treatment plant shuts down for dioxin testing
By Wendy Frew Environment Reporter, May 5, 2006
THE plant being used to treat a plume of toxic chemicals beneath parts of Botany has been closed down, after it was discovered dioxin was being released from the plant into the atmosphere at higher than acceptable levels.
The Department of Environment and Conservation yesterday asked Orica, the company that operates the plant and is responsible for the contamination of the groundwater, to voluntarily shut down its treatment plant following test results that revealed dioxin emissions at levels above licence conditions.
The department’s director general, Lisa Corbyn, said the plant would be shut down until the problem could be properly investigated and remedied.
“Although an Orica health risk assessment shows that these results will not have any significant impact on the community, we are taking no chances with the safety of the local residents and workers in the area,” Ms Corbyn said.
Dioxins are a group of hundreds of toxic chemicals that last a long time in the environment and build up in body fat.
Dioxins came to Sydneysiders’ notice recently because of high levels detected in harbour fish and in some of the commercial fishermen and their families who eat large amounts of it every week.
Ms Corbyn said when approval was granted to construct the Orica plant in February last year, there were many strict conditions attached to the consent, including stringent international standards on air emissions.
Orica told the department on Wednesday afternoon that on two recent occasions dioxin emissions had measured above those standards.
Orica began closing the plant at noon yesterday, but it will take three days before it is cool enough to enter.
Orica expects the plant to be closed for a week while work is carried out to ensure dioxin emissions do not again breach the accepted levels.
However, the company’s groundwater treatment project manager, Graeme Richardson, said the closure would not affect containment of the groundwater plumes, which move very slowly.
“We have always factored in a shutdown for plant modifications if required and this is part of that process,” Mr Richardson said.
The Orica contamination – left behind by the old ICI plant at Banksmeadow in the 1940s – will cost an estimated $167 million to mop up and may be the biggest and most expensive such job in the southern hemisphere.
The dioxin detected recently in Orica’s monthly emission tests is a by-product of the process used to strip contaminants from the water, and then burn them at very high temperatures.
Dioxins are originally formed when material burns, such as in bush fires or the processing of household or industrial waste. They are also produced in some industrial processes, such as the manufacture of pesticides.
The State Government last month caved in to public pressure by offering the harbour’s 44 commercial fishermen and their immediate families free dioxin tests.
Critics, including environmentalists and medical and chemical experts, have said the Government was not doing enough to make sure waterways were cleaned of toxic substances dumped decades ago by the likes of the chemical manufacturer Union Carbide, which is responsible for the harbour dioxins.
All fishing is banned around the old Union Carbide site at Homebush Bay and commercial fishing is banned throughout Sydney Harbour.