Burwood Beach and Boulder Bay waste water treatment works ocean outfalls

The Situation

To support decision-making about future wastewater management options for the Burwood Beach and Boulder Bay Wastewater Treatment Works, managed by Hunter Water Corporation, NSW, scientifically robust environmental assessment programs were required to assess with social and economic factors to arrive at a sustainable ongoing options for both plants.

Advisian (previously WorleyParsons) undertook the multidisciplinary Marine Environmental Assessment Program (MEAP) for the Burwood Beach and Boulder Bay WWTW Ocean Outfalls on the New South Wales Hunter Coast. The aim of the MEAP was to establish any gradient of impact of the ocean outfalls on the receiving environment with distance from the outfalls, the overall footprint in terms of environmental impact and to predict the footprint of any proposed future discharges.

Approach

The MEAP studies were undertaken over a two and a half year period, commencing in June 2011 and concluding in September 2013. The MEAP incorporated a mix of complementary physical, chemical and biological indicators to assess the overall effect of wastewaters on the ecological health of the local marine ecosystems. These included water quality and sediment quality, reef ecology, fish and infauna assemblages, seafood contamination and oyster bioaccumulation and ecotoxicology.

The combination of such a broad-range of studies afforded a more complete overall assessment or ‘weight of evidence’ in relation to ecosystem health. An integration report was prepared for each ocean outfall to bring together the results of the individual program components and provide an overall assessment of the environmental impact and the current environmental performance of the Burwood Beach and Boulder Bay discharges, as they affect the receiving waters and their associated ecosystems.

Results

Advisian successfully project managed, implemented and delivered over 18 concurrent offshore marine-based field studies, overcoming the numerous issues that can occur with field sampling in this type of environment.

Following the completion of these studies, impacts were detected but assessed to be localised and reversible. The results allowed a suitable option to be selected for the next Burwood Beach WWTW upgrade and ongoing operation, including a five-yearly marine environmental assessment. Decisions regarding Boulder Bay WWTW options are still under consideration.

Since the completion of this study, Advisian has also been engaged to undertake marine sediment and infauna studies in 2016 and 2017 for the Belmont WWTW Ocean Outfall, Hunter Water Corporation’s third ocean outfall