LEVELS of toxic chemicals in groundwater at RAAF Williamtown and parts of the Tilligerry state conservation area have been found to exceed drinking water standards, according to a report commissioned by the Department of Defence.
A draft of the document was given to state authorities two weeks before they warned local residents on September 3 to stop drinking their bore water and eating fish caught nearby or eggs from backyard chickens.
A final version of the ‘‘stage two investigation’’ report has now been released, ahead of a public meeting about the contamination to be held at Stockton RSL on Wednesday night to discuss the detection of the chemicals perfluoro-octane sulfonate and perfluoro-octanoic acid in water and fish at Tilligerry Creek and Fullerton Cove.
But it follows at least two earlier reports to Defence, in 2013 and 2003, warning of potential or actual leaking of the chemicals off the base.
The chemicals were contained in a fire fighting foam used at the base until it was officially phased out in 2012.
The new report says groundwater sampling done on the base showed concentrations of the chemicals exceeded drinking water criteria.
Concentrations in groundwater samples taken outside the base were generally lower, but some taken from land south of the base and to its east in the Tilligerry state conservation area also exceeded the drinking water standards.
As well, perfluoro-octane sulfonate had been found in surface water samples taken several kilometres east-northeast and south of the base, indicating that the chemical could spread longer distances and in different directions than was expected.
The highest concentrations of the chemicals were found on the base near its fire training pit.
More than 70 of 230 soil samples taken on the base had elevated levels of perfluoro-octane sulfonate.
Lower levels were found in Lake Cochran, Dawsons Drain, Moors Drain and Tilligerry Creek.
The report concluded the extent that the chemicals had spread off site still needed further investigation, along with the impacts on aquatic fauna at Tilligerry Creek and Fullerton Cove.
A ‘‘stage one’’ report, done in early 2013, said no chemicals had been found in Hunter Water’s bores but that they had been discovered in surface water and drain sediments both on and off the base, with some concentrations ‘‘exceeding the adopted health risk levels’’.
Defence was also warned in 2003 that its fire training pit appeared to be leaking and needed repairs.
The state government has convened an expert panel to oversee the problem, led by Chief Scientist and Engineer, Professor Mary O’Kane.
The Department of Primary Industries expected to receive the first results of its own testing samples conducted in the area by next week.
Advice issued by NSW Health on September 11 said blood tests can provide a measure of perfluoro-octane sulfonate but ‘‘are not recommended because they don’t predict level of health risk’’.
‘‘Whether [the two chemicals] causes adverse health effects in humans is currently unknown, but on current evidence, the potential for adverse health outcomes cannot be excluded,’’ NSW Health said.