The ‘poo pipe’ disposes of excess treated effluent onto Pambula/Merimbula beach. Photo: Brent Occleshaw for Bega Valley Shire Council.
Five years after an environmental review for a major coastal sewerage infrastructure upgrade was completed, more details about the project have been revealed.
Bega Valley Shire Council has been planning upgrades to the Merimbula Sewerage Treatment Plant (STP) for years, putting forward a proposal in information sessions in 2019.
It wants to replace the so-called ‘poo pipe’ that releases excess treated effluent onto Pambula-Merimbula beach, which is part of its current method of dealing with the region’s effluent.
It’s hoped an alternative – an ocean outfall pipeline – will address long-standing controversy about the current arrangement.
A document containing updated information and modelling was released this month.
Council’s manager of water and sewer services Steve Marshall said the document followed a 2021 environmental impact statement.
“After that process, the department asked us to prepare this PIR to make sure all the project information is up to date,” he said.
A Preferred Infrastructure Report (PIR) notes that there have been further studies into areas associated with the project since the 2021 report.
“Overall, the assessment concludes that the project does not introduce new impact pathways and does not increase the significance of impacts identified in the EIS,” the report states of the subsequent studies.
“Updated information provides additional confidence in technical performance and environmental protection outcomes, but does not alter the conclusions of the original assessment.”
The newer report notes that the project is still set to involve the installation of a 2.7-kilometre offshore pipeline, disinfection infrastructure and storage stations.
This will see the STP’s effluent disposed of into Merimbula Bay at a depth of 30 metres.
The upgraded STP facilities will use chemicals to remove phosphorus, with the specific chemicals to be determined during the detailed design stage.
One possible method – aluminium chloride dosing – would increase the amount of solids needed to be handled by almost 20 per cent.
“Any chemical dosing will increase sludge production relative to no dosing, with the magnitude dependent on the final phosphorus limits and detailed design,” the PIR revealed.
“The selected dosing approach will seek to optimise chemical consumption, sludge generation and operational efficiency while meeting regulatory requirements.”
Another of those assessments confirmed that demand, environmental impacts and land availability mean that “surplus” effluent remains a problem for the STP to manage.
This will replace two dunal exfiltration ponds (located to the east of the facility) and the decommissioning of the existing beach-face outfall.
“The project will provide a reliable method for disposing excess effluent unable to be supplied as recycled water when demand for recycled water is low,” the document outlines.
The report also confirms that about 25 per cent of the recycled water will still be supplied to the Pambula-Merimbula Golf Club and Oaklands agricultural area.
The report is available on the NSW Department of Planning, Housing and Infrastructure (DPHI) website until 25 June.
Once the exhibition period closes, DPHI will review submissions and make a recommendation to the Minister for Planning and Public Spaces who will rule on the project.
