Success in wastewater sustainability

A Sydney Water infrastructure project has received an excellent design rating from the Infrastructure Sustainability Council of Australia.

Sydney Water’s Lower South Creek Treatment Program has received what is claimed to be the highest rating ever achieved for an Australian water infrastructure project from the Infrastructure Sustainability Council of Australia (ISCA), earning an ‘Excellent’ IS Design rating of 69.7 points.The ISCA aims to enable sustainability outcomes in infrastructure, with a rating scheme that evaluates sustainability across the planning, design, construction and operational phases of infrastructure programs, projects, networks and assets.

Sydney Water’s Lower South Creek Treatment Program will involve the installation of new and upgraded wastewater infrastructure to improve quality, capacity and reliability at three wastewater treatment plants (WTPs) in Sydney’s north-west — Riverstone, Quakers Hill and St Marys — to support the additional half a million people projected to be living in the region by 2040.

The $450m upgrade of facilities at St Marys and Quakers Hill will see the adoption of innovative process technologies to make water treatment more sustainable, cost-effective and efficient.

ISCA CEO Ainsley Simpson said, “This is the highest IS rating ever achieved for a water infrastructure project and includes numerous innovations and sustainable outcomes which other water utilities can follow and learn from. A tremendous achievement for Sydney Water.”

ISCA Case Manager Kieren Heikkinen added, “The outcomes were particularly impressive considering the IS rating was initially undertaken as a benchmarking exercise with little additional effort expended on sustainability, which reflects Sydney Water’s focus on sustainable outcomes. Learnings from the project and IS rating can and should be applied across Sydney Water.”

Energy and carbon forecast modelling for the project estimates that the Sydney Water program will achieve a reduction of 870,000 tonnes (or a 42% reduction) of greenhouse gas total emissions during construction and across the 50 years of operation. This reduction includes embodied CO₂ emissions from construction materials and treatment chemicals.

On-site renewable energy use is a core objective of the project’s strategy, with the transfer of biosolids from Quakers Hill WTP to a regional biosolids hub at St Marys WTP creating feasibility for a new anaerobic digestion plant with thermal hydrolysis pretreatment (THP). This will deliver processing efficiencies and allow for cogeneration with energy recovery from the biogas produced. On-site thermal energy recovery and electricity generation will allow the program to self-generate 69% of its electricity demand.

The IS Rating Scheme

The Lower South Creek Program is Sydney Water’s first project to trial the ISCA’s IS Rating tool and certification process. This process has provided independent third-party assurance of sustainability outcomes in delivery of the project.

Sydney Water Lead Environmental Scientist Gill Fowler said, “Embarking on the IS journey provided greater incentive and opportunity to challenge current process thinking and explore new ways of operating. This helped drive sustainability benefits and reduced energy demand and our carbon footprint.

“Sydney Water has committed to obtaining a sustainability benchmark for all its major infrastructure projects,” she said.

To achieve Sydney Water’s first IS Rating, the program deployed several innovative processes and technologies, including the transfer of sludge for consolidated biosolids processing and installation of mechanical primary sedimentation screens, reported to be Australian firsts.

Other innovations included anaerobic digestion with THP at St Marys, with the secondary treatment process modified to a Nereda aerobic granulated sludge bioreactor after a successful pilot trial at the Quakers Hill plant.

This series of innovations helped to deliver industry-leading sustainability benefits, which resulted in an ISCA score of 10/10 for innovation; two of the innovation points were awarded for renewable energy supply and exceeding the benchmarks for energy and carbon reduction.

Benchmarking sustainability performance

The Lower South Creek Treatment Program used a novel approach to forecasting and benchmarking energy and carbon under the IS Rating tool. This involved comparison against robust energy benchmark data published by the Water Services Association of Australia from 245 WWTPs across Australia and New Zealand. The Lower South Creek Treatment Program’s delivery partners (WSP and UGL) put forward the IS tool to benchmark the project’s sustainability performance without incurring additional capital costs. This process has provided insights into how Sydney Water policies and procedures align with best practice in the IS Rating tool.

WSP Senior Sustainability Consultant James Logie said, “This is an amazing result for Sydney Water’s first IS Rating and highlights the impressive efforts from Sydney Water to plan and deliver innovative and more sustainable wastewater solutions.”

Program Director Anthony Korbel said, “ISCA certification of the Lower South Creek Treatment Program is a further step by the infrastructure industry, and in particular Sydney Water, in recognising the importance of sustainability in the delivery of large capital programs. It’s been both an interesting and rewarding process for the [WSP/UGL] team and I’m delighted to see such a fantastic result.”

Image courtesy of Sydney Water.