Sydney
9.9 Discharge from urban water system

Supporting Information

The volume of treated water from wastewater treatment plants and water recycling plants discharged to surface water during the 2010–11 year is 64,591 ML made up of flows that reached the sea (58,402 ML), and flows that reached downstream storages (6,189). Details of discharge volumes are provided in the following tables.

Sydney Water Corporation released 15,989 ML of recycled water from St Marys Water Recycling Plant to Boundary Creek (a tributary of the Nepean River). In the future, such releases are intended to replace outflows released for environmental purposes from Lake Burragorang (Warragamba Dam) to the river. The date for these releases is yet to be determined.

Breakdown of urban wastewater discharge to rivers

Description

Plant

Discharging to watercourse

Volume discharged during 2010–11 (ML)

Sydney Water Corporation – treated wastewater from water recycling plants

 

Castle Hill

Cattai Creek

2,991

Glenfield

Georges River

156

Liverpool

Georges River

1,434

Penrith

Boundary Creek

1,526

Picton

Stonequarry Creek

220

Quakers Hill

Breakfast Creek

6,946

Richmond

Rickabys Creek

501

Rouse Hill

Second Ponds Creek

3,887

St Marys

South Creek

3,662

St Marys

Boundary Creek

15,989

West Camden

Matahil Creek

1,805

Sydney Water Corporation – treated wastewater from wastewater treatment plants

 

Brooklyn

Hawkesbury River

94

Fairfield

Orphan School Creek

740

Hornsby Heights

Calna Creek

2,250

North Richmond

Redbank Creek

317

Riverstone

Eastern Creek

561

Wallacia

Warragamba River

227

West Hornsby

Waitara Creek

4,840

Winmalee

Nepean River

7,339

Shoalhaven City Council – treated wastewater from wastewater treatment plant

 

Berry

Broughton Creek

200

Bomaderry

Abernathy's Creek

844

Nowra

Shoalhaven River

1,873

Total

58,402

The volumes shown in the previous table reached the sea. They did not become inflows to downstream storages.

Treated water released from wastewater treatment plants to streams reaching downstream storages are detailed in the following table. The volume reported below has been deducted from 9.4 Rainfall runoff.

Details of discharge volumes to downstream storages are also available in line item 19.5.

Details of discharge volumes in downstream storages

Operator

Wastewater treatment plant

Discharging to watercourse

Reservoir receiving the discharge

Volume discharged during 2010–11 (ML)

Comments

Goulburn Mulwaree Council

Goulburn and Marulan

No

No

0

The plants received 2,517 ML

Treated water was used for irrigation

Lithgow City Council

Lithgow

A tributary of the Coxs River

Lake Lyell

2,036

Metered inflows to the plants

Wallerawang

Coxs River

Lake Wallace

            177

Palerang Council

Braidwood

A tributary of the Shoalhaven River

Lake Yarrunga (Tallowa Dam)

87

Estimated volume from metered inflow to the plant

Wingecarribee Shire Council

Berrima

Olbury Creek

Lake Burragorang (Warragamba Dam)

101

Recorded from outflow meters

Bowral

Wingecarribee River

1,594

Braemar

Iron Mines Creek

1,013

Bundanoon

Reedy Creek

283

Moss Vale

Whites Creek

Medway

898

Total

6,189

 

 

Quantification Approach

Shoalhaven City Council

Data Source

Shoalhaven City Council telemetry system. Daily data registers in respect of the operations of the plants.

Provided by

Shoalhaven City Council.

Method

Outflows from wastewater treatment plants were measured as follows:

  • Berry Wastewater Treatment Plant: Vega-type ultrasonic flow meter
  • Bomaderry and Nowra wastewater treatment plants: a Parshall flume with a venturi flow meter at each site.

Assumptions, Limitations, Caveats and Approximations

Nil.

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 Operations Division (Systems Assurance) of Sydney Water Corporation (SWC). Metered data reported in SWC's Water Efficiency Report 2010–11

Provided by

SWC.

Method

Total metered volume of treated wastewater discharge to surface water from SWC's wastewater treatment plants and water recycling plants is provided. Water from St Marys Recycling plant was measured using SWC's Water Efficiency Report 2010–2011.

The flow of wastewater and recycled water from plants was measured using flow meters. These measured data are continually monitored and recorded using the Integrated Instrumentation Control Automation and Telemetry System (IICATS). The data are stored within a complex data management system. Adjustments are made to the data (if necessary) to correct any interruptions, errors and so on. Data have been extracted for 2010–11 from the data management system.

Assumptions, Limitations, Caveats and Approximations

The main difference between treated wastewater and recycled water produced by SWC is quality, and quality is determined by the level of treatment. Recycled water is produced by treating water generated from sewage, greywater or stormwater systems to achieve high quality as required. Information on SWC's wastewater treatment levels in producing recycled water is available on their website.

Uncertainty Information

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

Comparative year

The following table compares the value for the 2009–10 year reported in this account with the corresponding value reported in the 2010 Account.

 

Comparative information from the 2010 Account for line item 9.1

2011 Account line item

2010 Account line item

Value reported in the 2010 Account (ML)

Value reported in the 2011 Account (ML)

Additional information

9.9 Discharge from urban water system  

13.7.1 Discharge of urban wastewater to connected surface water

54,576

56,556

Restatement: these two line items have been merged in the 2011 Account

13.7.2 Urban recycled water discharge to connected surface water

1,980