Sydney Water Annual Report 2009
Performance review: Optimising resource use
Sydney Water continues to expand renewable energy generation as part of its aim to reduce carbon emissions.

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Carbon neutral for energy and electricity use by 2020

Sydney Water is one of the largest energy users in NSW, consuming almost one per cent of the state’s electricity. Pumping stations and treatment plants used to treat and move water and wastewater around, utilise most of this electricity.

Sydney Water has continued to develop its Renewable Energy Generation Program as part of its aim to reduce carbon emissions by 60% by 2012 and be 100% carbon neutral for energy and electricity use by 2020. In 2008–09, Sydney Water achieved its target of a 24% reduction in greenhouse emissions.


Sydney Water captures biogas, produced in the wastewater treatment process, and converts it to electricity through a cogeneration process. This gas scrubber at the North Head Sewage Treatment Plant feeds into the cogeneration plant.

North Head Sewage Treatment plant

In an Australian first, Sydney Water will be generating hydroelectricity from wastewater flows within the network. Construction continued on the hydroelectric plants at North Head Sewage Treatment Plant as well as at Woronora and Prospect water filtration plants.

Cogeneration, using biogas, is another form of renewable energy being generated. Sydney Water captures the biogas, mainly methane, produced in the wastewater treatment process, and converts it to electricity through state-of-the-art combustion technology. Cogeneration plants have been operating successfully at Malabar, Cronulla and North Head.

During the year, Sydney Water completed work on the Bondi and Wollongong cogeneration plants. The Bondi plant was fully operational in May 2009 and Wollongong will be operating in August 2009. Final testing has commenced on the Glenfield, Liverpool and Warriewood plants, which will be operational in late 2009.

Once completed in November 2009, the 11 renewable energy plants will generate around 22% of Sydney Water’s energy. Greenhouse gas emissions will be reduced by about 80,000 tonnes a year. This represents over 15% of Sydney Water’s total emissions.

Sydney Water has begun reporting its emissions as required by the National Greenhouse and Emissions Reporting Act 2007.


Preparing for climate change

While climate variability is a key part of the Australian environment, Sydney Water is planning for the impacts of climate change. Both climate change and variability pose major challenges for delivering services to customers.

In April 2008, Sydney Water completed a qualitative assessment of the risk that climate change posed to its operations and infrastructure. Staff identified climate and weather related risks. These risks were ranked as higher or lower priorities based on their likelihood and consequence of occurring in 2030. Sydney Water has existing controls for the majority of the higher priority risks to reduce this likelihood or consequence.

Risks related to future sea level rises (combined with storm surge), bushfires, intense storms and extreme weather need further assessment.

Sydney Water will use the results of this assessment to prioritise research efforts over the next three years. Climate change risks will be integrated into all business areas including project planning, how sites are selected and managed, emergency response plans, business continuity plans, design standards and operational and maintenance protocols. Sydney Water is developing the business capability and tools to adapt to the future climate.

Low-lying pumping stations would be affected by rising sea levels

Low-lying pumping stations would be affected by rising seas levels.

Using 100% of captured biosolids

Biosolids are the nutrient-rich organic material produced during the treatment of wastewater at Sydney Water’s sewage treatment plants. This material is used in agriculture and composting.

One hundred per cent of biosolids captured during 2008–09 were beneficially used. Sydney Water has met this target for the past five years.

Sydney Water achieved a reduction in the total mass of biosolids produced in 2008–09 to 39,443 dry tonnes, or 184,764 wet tonnes. This is down about seven per cent from the amount produced in 2007–08, following major changes in treatment processes at key treatment plants.

In 2008–09, the Malabar plant stopped adding lime to dried biosolids, which reduced the dry mass produced by about 20%. The plant still captures solids at the same rate. New sludge digestion facilities installed at North Head Sewage Treatment Plant in 2007–08 also reduced the total mass of biosolids produced by removing the need for lime addition.


UK treatment methods may prove viable for Sydney

Vicky Burston and Jason Sylvester are Production Officers at Warriewood and North Head sewage treatment plants.

‘During 2008–09, we spent six months in the United Kingdom, on fellowships researching new biosolids treatments. We worked in the research and development division of United Utilities, in Manchester. We were involved in several projects examining the enzymic hydrolysis technique and other forms of pre-treatment developed there.

‘The enzymic hydrolysis process causes a rapid breakdown of large organic compounds, making it easier and quicker for the digesters to break the sludge down to produce methane gas and biosolids. With decreased retention time, increased biogas production, less odour and more stabilised biosolids, enzymic hydrolysis may prove a viable option for Sydney Water.

‘As a result of our research, Sydney Water is currently investigating pre-treatment of sludge before digestion. This would produce more gas for the cogeneration plants that supply power to Sydney Water’s sewage treatment plants.’

Biosolids compost

Biosolids compost

Recycled or reused 53% of solid waste

Sydney Water avoids generating waste whenever possible and aims to reduce waste through reuse and recycling. In 2008–09, Sydney Water recycled over 256,155 tonnes of waste. The amount of waste recycled or reused was 53%, compared to 86% in the previous year.

Recycling of construction waste was down significantly, compared to previous years. This was mainly due to high volumes of excavated soil generated from the water mains renewals and replacement flows construction projects. The bulk of the soil from the replacement flows project was contaminated and could not be reused.

During 2008–09, Sydney Water:

  • reduced the amount of waste generated from its Priority Sewerage Program by using pressure sewerage technology instead of gravity systems where possible
  • used pipe bursting methods on renewal work to reduce waste generation and spoil disposal
  • reduced the amount of spoil created during pipeline construction by changing from trenched to trenchless methods where possible
  • recycled 56% of grit and screenings from sewage treatment plants
  • recycled 50% of the sediment removed from stormwater channels and stormwater quality improvement devices
  • beneficially reused 95% of sediment removed during dredging of sewer mains
  • recycled 429.5 tonnes of office waste.

In line with the NSW Government’s Waste Reduction and Purchasing Policy (WRAPP), Sydney Water’s Waste Minimisation Procedure and plan includes strategies for communicating, measuring, reporting, target setting, procurement, planning and evaluation, and review. For more information, see Sydney Water’s 2008–09 WRAPP Statement.

Advances in bush regeneration and land management

Sydney Water is responsible for several wetland and creek systems around Sydney. This year, Sydney Water made significant advances in weed control, bush regeneration and land management.

A new method to plan and cost aquatic weed management has been developed. The NSW Weed Committee, local government and various state and commonwealth agencies are looking at adopting Sydney Water’s method once fully developed.

At the Botany Wetlands, near Southern Cross Drive, action continued to control weed infestations and protect the endangered Eastern Suburbs Banksia Scrub. An unexpected blue green algal bloom was washed into the wetland from upstream, requiring additional monitoring. A survey of birds using the wetland was also completed. This is done each five years.

The Eve Street wetlands at Kyeemagh include a salt marsh and mudflats. During 2008–09, Sydney Water repaired damage caused by road building and did weed management and bush regeneration work.

Sydney Water is the custodian of 245 hectares of stormwater drainage land, wetlands and basins in the Rouse Hill Development Area. In August 2008, Sydney Water participated in The Hills Shire Council’s Bushcare Expo for the local community. In early 2009–10, a Memorandum of Understanding will be signed with the council so their bushcare groups can help Sydney Water restore areas of endangered native bushland.

Replanting native vegetation helps filter pollutants from runoff, improving the quality of stormwater flowing into the Hawkesbury-Nepean River and reducing the impact of noxious weeds and introduced species on aquatic ecosystems. Over the past three years, Sydney Water has planted over 2.6 million plants in the Rouse Hill Development Area.

During 2008–09, Sydney Water let several major contracts for control of aquatic and terrestrial weeds, bush regeneration and native vegetation management at Rouse Hill. A $1 million weed control contract was awarded in August 2008 for five years. Work also started in August 2008 under a five-year bush regeneration contract worth $1.88 million.

This work will supply green corridors and help protect a valued habitat for flora and fauna.

In February 2009, Sydney Water started using a new Environmental Assessment Tool to support information sharing across Sydney Water.

More performance information on optimising resources is available in the Sustainability indicators section of this report.

The Sydney Water website contains more information on this topic.