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Lower South Creek Treatment Program

With northwest Sydney expecting another half a million residents by 2040, Sydney Water¡¯s Lower South Creek Treatment Program is helping future proof essential infrastructure. The upgrades at Riverstone, St Marys, and Quakers Hill wastewater treatment plants are designed to increase capacity, improve environmental outcomes, and support population growth.

We¡¯ve supported Sydney Water on this program since 2016, starting with detailed design at Riverstone. Our involvement expanded to include concept and detailed design at St Marys, further upgrades at Riverstone, and detailed design at Quakers Hill. We¡¯ve remained involved as technical support throughout construction and commissioning.

Together, the upgraded plants now treat over 100 million litres (over 26 million gallons) of wastewater a day¡ªservicing more than 600,000 people. The program delivered several firsts, including Australia¡¯s first mechanical primary screens at all three sites and the country¡¯s largest aerobic granular sludge bioreactor at Quakers Hill. We also supported Sydney¡¯s first pumped sludge transfer between plants using an existing 12.5-kilometre (7.8-mile) pipeline.

Working within active brownfield environments, we delivered upgrades across inlet, secondary, tertiary, and disinfection processes. Our building information model, supported by over 1,000 drawings, helped guide construction and identify efficiencies. The program was recognized by the Infrastructure Sustainability Council for achieving the highest sustainability design rating in Australia at the time.