Clarification on Ocean Outfall

7 November 2019

Bega Valley Shire Council would like to clarify a number of points on the process that has led up to Council’s decision on the location of the proposed ocean outfall in Merimbula Bay, in the light of recent media coverage, following Council decision on 30 October 2019. 

The Merimbula Ocean Outfall and Sewage Treatment Plant upgrade has been a long-term project with a considerable amount of expert scientific and technical input, alongside engagement with the community, regulators, staff and councillors.  

In the mid-2000s, concerns were raised about the dunal exfiltration system and beach face outfall at Merimbula.  In 2008, the Environment Protection Authority (EPA) placed a condition on the Merimbula STP environment protection licence requiring BVSC to comprehensively investigate both the beneficial reuse and disposal options available for treated effluent generated at Merimbula.   

At the completion of the investigation into those options, Council, in July 2013, resolved to adopt an effluent management strategy, including a sewage treatment plant upgrade to improve effluent quality and construction of a deep water ocean outfall for disposal of effluent unable to be used beneficially.

The resolution was adopted in consideration of the recommendations of the focus group of stakeholders, which included representatives from the EPA, catchment management authorities, oyster growers and other concerned stakeholders.

Subsequently, in 2013, the EPA updated the conditions of the Merimbula STP licence requiring BVSC to obtain the necessary approvals to construct and commission a deep-water ocean outfall for the disposal of treated effluent from the plant.

Since that time the project has developed based on increasing levels of understanding underpinned by scientific and engineering study, along with stakeholder input.  Council’s adoption of the “north short” outfall diffuser location last week is supported by up to date oceanographic modelling that wasn’t available in 2013.   The modelling has given us better understanding of the impact of the currents and what happens to effluent discharged from the outfall which will achieve acceptable ambient water quality.

Council’s decision to construct a new outfall on a northern alignment 2.6 kilometres out to sea and 30 metres underwater provides a sustainable disposal option to return treated effluent back to the environment when it cannot be reused.  Council also decided to treat the water to a higher standard including an additional sand filtration step, further phosphorous removal and UV disinfection.

The solution will deliver significant environmental, cultural and public health improvements over the existing beach outfall and exfiltration ponds.

At the same meeting on 30 October 2019, Council also reinforced its commitment to expanding effluent reuse by resolving to undertake further investigations of effluent storage at the Pambula Merimbula Golf Club, which is one of several re-use schemes in operation across the Shire.

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