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Wastewater Project of the Year

For the wastewater project, commissioned during 2020, that shows the greatest innovation in terms of optimising its physical or environmental footprint.

Sydney Harbour stormwater management, Australia

What is it?

An A$50 million project aimed at separating the last remaining combined stormwater and wastewater systems in Sydney, part of the huge Refresh Woolloomooloo legacy programme. It included laying 4.2km of wastewater pipes and 650m of stormwater pipes in a dense urban area, connecting over 200 properties, as well as the construction of 140 maintenance manholes, and repair to vent shafts. Full completion was achieved in March 2020.

Who is involved?

Sydney Water took an integrated team approach, taking on GHD to lead planning and design, and Diona Civil Engineering for the construction stages. Pezzimenti and UEA Australia were responsible for the trenchless pipe installation and technology, and Rocla supplied the prefabricated manholes.

What makes it special?

This was an extremely high-impact project as a result of the densely populated location, affecting more than 30,000 customers in the Woolloomooloo, Potts Point and Darlinghurst areas. The location challenges led the team to adopt advanced technologies like prefabricated manholes, that reduced installation times from 21 days to 3-5 days. State-of-the-art trenchless construction techniques such as bed bores, stitch boring and micro tunnelling were deployed, reducing noise impacts and minimising the impact on the environment.

The improved system now captures and transfers wet weather wastewater overflows in the Woolloomooloo catchment into the Bondi treatment plant. It has also eliminated wafted odours during the dry weather, which were a main cause of complaint for the surrounding community. The new separated system ameliorates the liveability of the area, minimises the contamination of the Sydney Harbour and bay, enhances its water quality and improves marine life.


The integrated team approach meant that a wide variety of stakeholders were involved in the planning and designing from the beginning of the project. It ably facilitated the community’s cooperation and involvement and led to exceeded public expectations.


Riviera Utilities WWTP upgrade, USA

What is it?

An advanced secondary treatment upgrade at a wastewater treatment plant in Wolf Creek, Alabama, that marks the first installation in the US of the AquaNereda aerobic granular sludge technology. The WWTP treats an average flow of 13,248m3/d and can handle a peak flow of 22,710m3/d.

Who is involved?

After a competitive bidding process, Riviera Utilities contracted Goodwyn, Mills and Cawood Inc. to design the upgrades in a $20 million project. Aqua-Aerobic Systems provided the AquaNereda systems, as the local supplier for technology developer Royal HaskoningDHV. It also provided AquaDisk cloth filtration media, while Hidrostal supplied the main lift station. Other key contractors involved were water and wastewater specialists Automation Control Service and Max Foote Construction.

What makes it special?

Instead of taking the straightforward approach of increasing the treatment capacity, this project also future-proofed the plant in anticipation of more stringent effluent limits for nitrogen and phosphorus, which are expected to be enacted in the future. In addition, the solution offers advanced biological nutrient removal without requiring multiple tanks, pumps, and mixers.

The upgrades provide smart aeration control, reduced equipment needs, and an improved substrate and oxygen utilisation through the use of granular sludge, transforming the plant’s operating capabilities. The adoption of the AquaNereda technology also led to huge energy cost savings of between 40% and 50% with an energy consumption rate of less than 0.3kWh/m3 registered in the first months of operation. The high operating mixed liquor solid suspension level, exceeding 8g/L, reduces settling time, producing a higher quality effluent with a vastly reduced plant footprint.


The improved capacity of the plant has meant that it can treat higher flows of effluent, including stormwater from tropical storms and hurricanes, which are very common in the region. In the midst of these challenging conditions, there is no subsequent decrease in discharge quality or degradation of the plant’s performance.

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