Sydney Water Annual Report 2009
Performance review: Contributing to clean beaches, oceans, rivers and harbours
Sydney Water is
working with
councils and
businesses to
set up small,
local stormwater
harvesting schemes.

In this section:

download View our sustainability performance indicators for this goal

Meeting Sydney’s growth by upgrading capacity

During 2008–09, Sydney Water maintained sewage treatment plant performance and reliability, while increasing the capacity to service population growth.

Work to upgrade capacity was completed at Warriewood and West Camden sewage treatment plants, is nearing completion at Bondi and is underway at North Head, Winmalee and Rouse Hill plants.

Sydney Water, through an alliance with United Group, John Holland Group, MWH Australia, Worley Parsons and Manidis Roberts, is delivering a $150 million improvement program at North Head. This will ensure reliable plant performance, maintenance of wastewater quality and a safer work environment. Improvements completed during 2008–09 included:

  • constructing a new biosolids management facility that uses a digestion process to reduce the amount of biosolids from three or four truckloads a day to one load
  • constructing a cogeneration power plant producing about 15% of the plant’s energy needs.

In September 2008, construction work started on a two-megawatt hydroelectric plant. The plant, an Australian first, will produce energy from treated wastewater as it falls 60 metres to the deepwater ocean outfall.

Sydney Water is upgrading the Northside Storage Tunnel’s pump station and wet well at North Head, providing additional sedimentation tanks and overhauling the plant’s electrical and control systems. These will be completed in late 2009.

At Winmalee Sewage Treatment Plant, Sydney Water is improving overall reliability and the quality of treated wastewater leaving the plant. Construction began in February 2009 and will be completed by December 2010.

Work to minimise odours at Warriewood Sewage Treatment Plant and to support further residential development in the existing buffer zone, was also completed by Sydney Water.

Rouse Hill Recycled Water Plant was enlarged to accommodate the growth in the north-west of Sydney. Customers use the recycled wastewater from this plant to flush toilets and water gardens.

West Camden Sewage Treatment Plant was enlarged to process 8.4 billion litres a year – more than double its previous capacity of 3.9 billion litres. The plant will supply up to 1.8 billion litres of high quality treated wastewater a day for local agriculture use, such as turf and lucerne crops and in dairy farming. This means the volume of water taken from the Hawkesbury-Nepean River for these purposes will be reduced.

This upgrade will cater for future population growth, projected to be 80,000 during the next 20 years. It will also help improve the quality of wastewater being released into the Nepean River.

In February 2009, Sydney Water began detailed design work on major new water, sewer and recycled water services for the North-west Growth Centre. A 40 million litre drinking water reservoir and about 24 km of water, wastewater and recycled water mains will be built to service 6,000 new homes.

Australian Water, using Reed Construction as its design and construction contractor, will deliver the $90 million project under contract to Sydney Water. Construction has started and will be completed in early 2011.

Reducing overflows and sewer blockages

Under its Sewer Fix Program, Sydney Water inspects and repairs the sewerage network. Sewers can be damaged by corrosion, subsidence and human activities. Sewer blockages result from the build-up of silt and debris and the intrusion of tree roots. The disposal of oil, grease and non-dispersible solids to sewers adds to the problem. Clean, structurally sound sewers are less likely to block or overflow.

This year, Sydney Water inspected 260 km of large high-risk sewers to ensure they did not fail and spent over $54 million to rehabilitate 16 km of large sewers. This included repairing the:

  • Western Branch Main Sewer, between Marrickville and Burwood
  • Southern Suburbs Ocean Outfall Sewer at Botany from Hayden Place to Excell Street.

Repair work also began on the North Georges River submain, between Peakhurst and Padstow, and the Northern Suburbs Ocean Outfall Sewer at Manly.

During 2008–09, Sydney Water also focused on inspecting and repairing low-risk sewers. This included:

  • inspecting 344 km of sewerage pipes at a cost of $3.8 million
  • lining 62.5 km of pipes at a cost of $18.7 million
  • completing 1,173 dig and repair jobs at a cost of $5.7 million
  • cleaning sewerage pipes at a cost of $9.7 million.

Significant research into better managing odour and corrosion is being done, including a five-year project with the Australian Research Council.

In 2008–09, 16,028 private properties were reported as affected by dry weather uncontrolled sewage overflow, compared to 18,148 in 2007–08. The biggest single cause of dry weather overflows is tree roots breaking into sewer pipes.

Sydney Water has significantly reduced wet weather overflows into Sydney Harbour at Neutral Bay. This is part of the $200 million SewerFix Wet Weather Overflow Abatement Program.

The project, which started in February 2009, will see the construction of an underground pumping station to pump excess wet weather flows to North Head Sewage Treatment Plant.

Overflows at this location occur about 200 times every 10 years. This solution will reduce overflows by 90%, protecting the environment and meeting the Department of Environment, Climate Change and Water’s licence target of 20 spills every 10 years.


Beachside residents help reduce sewer overflows

Residents of Bondi, Bronte and Tamarama are helping protect local waterways and reduce sewer overflows by removing tree roots from their private sewerage pipes.

Tree roots entering public sewers from privately owned pipes can cause wastewater to build up and overflow into the environment, potentially reaching waterways such as Bondi Beach.

Sydney Water contacted about 30 households in late 2008–09 to alert them that tree roots in their sewerage pipes were affecting the public sewers.

Residents responded positively, with two thirds taking prompt action to clear roots from their pipes. Waverley Council also took action, clearing street tree roots from private sewerage pipes.

Residents can reduce the risk of overflows by having their sewerage pipes cleaned by a licensed plumber every couple of years and by being careful what they plant near their sewerage pipes. About 40% of the dry weather sewer overflows from the public sewerage system that reach waterways are caused by tree roots that have entered private sewers.

Sydney Water has a four-year, $560 million maintenance program for its 24,000 km network of sewerage pipes. However, there is another 22,000 km of privately owned sewerage pipes connecting homes to Sydney Water’s network.

Removing tree roots from a sewer

Removing tree roots from a sewer

Better managing trade waste

Trade wastewater discharge can contain chemicals and heavy metals and must be managed to protect the health of waterways, sewers and Sydney Water’s staff.

In 2008–09, about 15.6 billion litres of trade wastewater was discharged into the system, compared to about 16 billion litres in 2007–08. As the Sydney region has a relatively small manufacturing base, year-to-year changes in business numbers and processes affect the amount of trade wastewater discharged.

During the year, Sydney Water introduced Wastelink, an updated electronic system to manage greasy waste. The system records when businesses clean their grease traps and creates a reminder for the next pump out.

Sydney Water worked with businesses in the Smithfield area to significantly reduce their trade waste, discharges which have caused serious corrosion to local sewerage pipes. Six companies with large trade waste discharges were identified by Sydney Water, four of which needed major upgrades of their own wastewater treatment plants.

The largest customer, Visy Paper, made a major investment in a new plant to more effectively treat their waste. Arnotts Snack Foods, Australian Cooperative Foods and Golden Sunshine Foods also installed new treatment systems.

Other companies such as Coca-Cola made extensive changes to their processes to improve the quality of their discharge.

With these new treatment systems fully operational in late 2009, Sydney Water expects a major reduction in corrosive trade wastewater discharging into sewers in the Smithfield area.

Sewering communities, especially environmentally
sensitive areas

The Priority Sewerage Program provides improved wastewater services to urban areas that are serviced by on-site wastewater systems, such as septic tanks. The Department of Environment, Climate Change and Water identified these areas as having high environmental sensitivity.

In January 2009, Sydney Water completed the $156 million Upper Blue Mountains Sewerage Scheme that serves about 1,400 properties in Mount Victoria, Blackheath and Medlow Bath. The scheme will help improve water quality in local creeks and streams and help protect the Blue Mountains World Heritage Area.

Sydney Water began planning work during 2009 on a sewerage scheme for Agnes Banks and Londonderry, with $30 million committed to the project. From the middle of 2010, the first of about 290 households in Agnes Banks and Londonderry will be able to connect to the new sewerage service. Five km of sewerage pipes will be laid to transport wastewater from the two villages to Richmond Sewage Treatment Plant.

The Hawkesbury Heights and Yellow Rock Sewerage Schemes will provide improved sewerage services to unsewered urban areas through the installation of a pressure sewerage system. Connections to the sewer system are expected to be available to eligible properties from 2010. Wastewater from both Hawkesbury Heights and Yellow Rock will be transferred to Winmalee Sewage Treatment Plant.

In May 2009, work started on the $138 million sewerage scheme for the villages of Glossodia, Freemans Reach and Wilberforce. The scheme includes building a pressure sewerage system and 20 km of transfer pipeline to transport wastewater to the Richmond Sewage Treatment Plant. About 1,660 households will be eligible to connect to the new sewerage system when it is completed in 2011. The scheme will help improve the quality of the Hawkesbury River and protect public health by reducing the risk of runoff from on-site septic systems.

Working smarter to capture stormwater

Stormwater is rainwater that is collected from roofs, the ground, roads and other surfaces. It is often polluted and needs treatment before the water is suitable for use.

‘Stormwater needs to be stored for use, but it comes in anything from a trickle to a flood. Reservoirs to hold, and plants to treat, the collected water are expensive to build and challenging to fit into Sydney,’ Chris Davis, Interim Chair, Metropolitan Water Plan Independent Review Panel said.

‘Stormwater harvesting is usually only practical if there is a convenient pond, an aquifer or some other existing storage.’

The estimated stormwater runoff in Sydney each year is equivalent to the volume of Sydney Harbour. Stormwater generally flows into small street drains owned by local councils and then into much larger pipes or channels. Sydney Water owns less than five per cent of these channels, but they drain 25% of Sydney’s stormwater. It makes sense to work with councils and businesses to set up small, local harvesting schemes.

Over the year, Sydney Water and the City of Sydney Council worked jointly on a stormwater harvesting project in Sydney Park at St Peters to irrigate a section of the park. The council will complete construction of Stage 1 of the project in 2009–10. Stage 2 will use filtered stormwater for further irrigation and may also supply nearby commercial and industrial premises if the natural treatment system achieves water of suitable quality. Treating and reusing stormwater will also help improve water quality in Alexandria Canal.

Sydney Water is also working with local councils and other stakeholders to replace sections of concrete banks in the Cooks River stormwater channel. Three priority sites have been chosen for bank replacement:

  • Cup and Saucer Creek, adjoining the Cooks River in Canterbury
  • near Flockhart Park in Campsie
  • near Whiddon Reserve in Belfield.

In December 2008, Sydney Water displayed draft designs for the three sites to the community. The design work took into account flooding and sea level rises resulting from climate change. In June 2009, Sydney Water completed the site investigations required to finalise the concept design. Work will start at the Cup and Saucer Creek site in early 2010.

Powells Creek, next to Bicentennial Park in Homebush, carries stormwater to the Parramatta River, and adjoins the sensitive Mason Park salt marsh wetland. Sydney Water completed a flood study this year and concept design work progressed for renewal of the stormwater channel banks. A similar approach to the bank replacement works along the Cooks River is proposed. Residents will continue to be consulted and the construction of new banks is due to commence in late 2010.


Heritage award for stormwater channel built in 1863

In May 2009, work to restore one of Sydney’s oldest stormwater channels earned Sydney Water an Engineering Excellence Award, from the Institute of Public Works Engineering Australia. The Hay Street channel was built as a sewer in 1863 and converted to a stormwater channel in the early 1900s.

Repairs to the channel had to strike a balance between maintaining operations and protecting its historical value. Sydney Water investigated over 20 repair options before inserting a liner inside the stormwater channel in late 2007. This ensured the channel was structurally sound while protecting the original stonework from further erosion.

The original channel is built from sandstone blocks. The liner is elliptical in shape and a membrane covers the stonework. Importantly, the liner can be removed in future without damaging the heritage stonework.

The methods used in the $4.1 million project were specifically developed to suit the unique conditions in the Hay Street channel. With its new liner, the Hay Street channel can continue to play a role in Sydney’s stormwater operations for many years to come.

Hay Street stormwater channel restoration project

Hay Street stormwater channel restoration project

The Sydney Water website contains more information on this topic.