The plant to treat fire fighting foam contaminants perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) from leaving the base’s man-made Lake Cochran should be operating by September.

The water treatment plant was announced on Friday by Assistant Minister for Defence Michael McCormack.

Defence will fund the plant to ensure PFOS and PFOA levels in water leaving the lake, which is a retention basin for the base and close to a boundary, are below accepted drinking water levels.

Ground and surface water from Lake Cochran leaves the base and flows into Dawsons drain. The water has been found to have extremely high levels of PFOS and PFOA.

“The installation of a water treatment plant is an important interim step while Defence continues to investigate long-term remediation options for Lake Cochran,” Mr McCormack said.

“An expression of interest for the long-term remediation of Lake Cochran will be released to industry in July.”

Mr McCormack noted that retiring Paterson MP Bob Baldwin had consistently argued that cleaning up Lake Cochran had to be a priority to prevent contaminated water leaving the base and entering surrounding areas, including privately-owned land.

“Once the necessary materials arrive from Europe, it is expected the plant will be up and running in September,” Mr McCormack said.

“These steps are being taken now after extensive testing and careful consideration of water remediation techniques to ensure an effective methodology with a proven solution is adopted.”

Defence is also carrying out a Stage 2B environmental investigation at Williamtown after the extent of contamination both on and off the base was revealed in September 2015, at least a decade after Defence first knew about fire fighting foam contamination at the site.

Mr McCormack said Defence had collected more than 900 samples of groundwater, surface water, soil, sediment and biota in and around RAAF Base Williamtown as part of the environmental investigation.

PFOS and PFOA had not been detected in 80 to 90 per cent of samples taken across the investigation area declared by the NSW Environment Protection Authority in 2015.

“Most people living in developed nations have some PFOS and PFOA in their systems as these compounds have also been used in common household products and industrial applications,” Mr McCormack said.

“It is also important to note, the enHealth guidance statement states there is currently no consistent evidence that exposure to PFOS and PFOA causes adverse human health effects.”