Sydney
11.4 Wastewater collected

Supporting information

a. Sydney wastewater system overview

The wastewater system is one of three sub-components of Sydney's urban water system.  The three sub-components are the:

  • Urban water supply system
  • Wastewater system
  • Recycled water system.

In the Sydney region, wastewater is collected from users by the Sydney Water Corporation, Shoalhaven City Council or Wingecarribee Shire Council (11.4) and transferred to wastewater treatment plants throughout the region.There is also some stormwater ingress reported by Wingecarribee Shire Council which is considered a wastewater inflow (11.7).

During the 2011–12 year, 7% of treated wastewater was recycled; 78% discharged to the sea (19.7); and the rest discharged to inland surface water (19.5). The following figure shows all the inflows and outflows associated with the wastewater system.

For more detail on a particular flow associated with the wastewater system, refer to the line item notes. Note that volumes annotated with a * indicate flows between sub-components and are not reported in the account. As such, these flows do not have an associated line item number.


The Sydney region's wastewater system using data retrieved from Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council
The Sydney region's wastewater system using data retrieved from Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council

b. Volume of wastewater collected in the Sydney region

The volume for the line item is 601,502 ML.

A breakdown of the wastewater collected by the urban system is provided in the following table.


Volume of wastewater collected by the urban system during the 2011–12 year

 Council/Corporation

Wastewater volume collected

(ML)

Sydney Water Corporation

588,098

Shoalhaven City Council

8,525

Wingecarribbee Shire Council

4,879

Total

601,502



A breakdown of the wastewater treated by Sydney Water Corporation and collected by Wingecarribee Shire Council is provided in the following tables. A breakdown of the Shoalhaven City Council wastewater volumes is not available.



Volume of wastewater collected by Sydney Water Corporation during the 2011–12 year
Plant type Watewater Treatment Plant Volume of effluent treated (excluding volume of treated for on-site use) (ML)
Water recycling Bombo 1,900
Castle Hill 3,695
Gerroa 460
Glenfield 645
Liverpool 5,238
Penrith 9,856
Picton 1,028
Quakers Hill 14,282
Richmond 861
Rouse Hill 7,330
St Marys 17,277
West Camden 4,342
Wollongong 24,601
Camellia1
2,156
Wastewater treatment Bellambi2 1,018
Bondi 50,234
Brooklyn 100
Cronulla 23,288
Fairfield2 3,543
Hornsby Heights 2,990
Malabar 195,446
North Head 162,071
North Richmond 417
Port Kembla2 888
Riverstone 771
Shellharbour 7,743
Wallacia 372
Warriewood 8,092
West Hornsby 5,554
Winmalee 8,626
Sewer mining3
803
Modelled network wet weather overflows 
22,471
Total 588,098

1 Recycled water agreement - Veiolia accesses Sydney Water Corporation's secondary treated wastewater and further treats for Sydney Water Corporation's customers

2 A wet-weather wastewater treatment plant, which is only used during major storms

3 Volume of sewage supplied to other infrastructure operators


Volume of wastewater treated at Wingecarribee Shire Council wastewater treatment plants
Wastewater treatment plant Total wastewater treated in the 2011–12 year (ML)
Berrima 1,892
Bowral 352
Bundanoon 1,286
Mittagong 1,220
Moss Vale 129
Total 4,879


Quantification approach

Shoalhaven City Council

Data source

New South Wales Office of Water calculations.

Provided by

Shoalhaven City Council.

Method

This item represents the total metered volume of wastewater collected by Shoalhaven City Council's wastewater treatment plants.

The calculation includes:

  • grease trap waste
  • on-residential
  • residential
  • septic tank effluent
  • septic tank sludge/pan
  • tradewaste.

Assumptions, limitations, caveats and approximations

The volume of wastewater collected/treated at sewerage treatment plants may also include any net ingress of stormwater or groundwater to the sewer system.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 5%.

Sydney Water Corporation

Data source

Data managed and maintained in an internal data management system by Sydney Water Corporation's Service Delivery Division (Assurance and Monitoring).

Provided by

Sydney Water Corporation.

Method

Volumes for both components have been derived from metered outflow data from the plants. The flow meter data are continually monitored and recorded using the Integrated Instrumentation Control Automation and Telemetry System (IICATS). The data are stored within an internal data management system. Adjustments are made to the data (if necessary) to correct any interruptions, errors and so on. From the data management system, data have been extracted for the reporting period.

Modelled wet weather outflows are determined by the hydraulic sewer system model. Wet weather overflow events are defined as sewage overflow that is not the result of an identified blockage in the Sydney Water Corporation's sewerage system or a system failure. It is a result of failure in the systems capacity. Wet weather overflow volume and events will be measured by the hydraulic system models as specified in the Environmental Protection Authority Sewage Treatment System Licences.

Assumptions, limitations, caveats and approximations

  • The volume does not include water losses in the treatment process including biosolid removal, de-watering and evaporation.
  • Total wastewater treated can include net ingress from stormwater and groundwater.
  • At wet-weather wastewater treatment plants, wastewater treated usually also includes a certain volume of stormwater.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%.

Wingecarribee Shire Council

Data source

Wingecarribee Shire Council Plant Supervisory Control and Data Aquisition (SCADA) Citec records and Department of Environment and Climate Change annual return reports 2011–12.

Provided by

Wingecarribee Shire Council.

Method

This item represents the total volume of wastewater collected at wastewater treatment plants.  The volume is derived from data from inflow meters at wastewater treatment plant where applicable.

Assumptions, limitations, caveats and approximations

Total wastewater received can include net ingress from stormwater and groundwater. Inflows to plants have only been measured at Moss Vale, Berrima and Bundanoon wastewater treatment plants. Therefore, treated volumes shown above are the same as discharge volumes shown under 'Volume of (treated) wastewater discharged to surface water' for these plants.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy and professional judgment is +/– 7%.