Page 2030 - Week 07 - Wednesday, 28 June 2023

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Lower Molonglo Water Quality Control Centre—wastewater treatment

MS CLAY: My question is to the minister for water. At Belconnen Community Council on 20 June, Icon Water told us about treatment at the Lower Molonglo Water Quality Control Centre in Holt. Residents raised various concerns.

Can you tell me what existing water treatment methods are in use out at the centre, and what new treatment method is proposed?

MR RATTENBURY: The Lower Molonglo Water Quality Control Centre was built in the mid-1970s and is currently on schedule for an upgrade. It was built to service the needs of a population of around 400,000 people. We have obviously exceeded that now, and the site has the potential to be extended to serve up to one million people.

The site can be split into primary, secondary and tertiary treatment processes, and these employ a series of techniques including physical, chemical and biological treatment processes. The treated effluent is water discharged into the Molonglo River under an environmental authorisation, which then flows into the Murrumbidgee River. They are the current methods—to go to Ms Clay’s question.

In terms of the new treatment methods, there are a number of proposals that have been put forward by Icon Water to upgrade various parts of the facility. These include the replacement of the existing furnaces, which is about renewing current technology, and then upgrade of the secondary treatment bioreactors, which is very much about the population growth of the territory.

Icon Water has also commenced a sewer master planning exercise to identify how to increase the capacity of sewerage collection and treatment infrastructure across Canberra over the next 50 years—again, to deal with that question of a growing population and ensuring the quality of the treatment of the water is adequate.

MS CLAY: How will the centre manage odours to make sure they do not impact on residents nearby in Holt and in Ginninderry? 

MR RATTENBURY: This is obviously a really important consideration. Whilst many people do not know where the sewerage treatment plant is, because it is quite a long way towards the edge of the city, obviously those in the nearby areas of Belconnen will have a particular interest in this question.

Odour modelling has been undertaken under the supervision of a working group comprising the Environment Protection Authority, Icon Water and the Environment, Planning and Sustainable Development Directorate. The study is overseen by a project auditor who reports to the Environment Protection Authority.

Icon Water did conduct a multi-criteria analysis of technological solutions to control odours from the odorous areas of the plant, and that work has now been completed. The projects are now at a concept design stage, with consultation with stakeholders currently underway, and they will be subject to the development of a business case and approval processes. The total cost of these projects is around $15 to $20 million.

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