Sydney

20.4.2 Wastewater discharge out of the region

Supporting information

The total metered volume of treated wastewater discharged to the sea at wastewater treatment plants and water recycling plants managed by Shoalhaven City Council and Sydney Water Corporation during 2009–10 was 395,186 ML (see the following table).

Managing authority	Plant type	Plant	Discharge volume to sea (ML)
Shoalhaven City Council	Wastewater treatment	Shoalhaven Heads*	152
Sydney Water Corporation	Wastewater treatment	Bellambi	356
		Port Kembla	505
		Warriewood	5,811
		Shellharbour	6,056
		Cronulla	18,865
		Bondi	44,548
		North Head	133,570
		Malabar	171,557
	Water recycling plant	Gerroa	148
		Bombo	1,327
		Wollongong	12,291
Total			395,186
* Discharge occurs via sand dunes to the sea.

Quantification approach

This line item comprises two different data-sets. The method for each data-set is shown below.

Note a: Shoalhaven City Council

Data source

NSW Water Supply and Sewerage: ‘Performance monitoring’ Report 2009–10. (Access through the ‘Performance monitoring’ webpage of the NSW Office of Water. The report will be included on the webpage from June 2011.)

Data provider

Shoalhaven City Council.

Method

Outflow volumes from Shoalhaven Heads Wastewater Treatment Plant were measured using an Elster meter and a Parshall flume with a venturi flow meter.

Uncertainty

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

Approximations, assumptions, caveats/limitations

Treated wastewater was discharged to the sea via sand dunes, which act as natural sand-bed filters.

Note b: Sydney Water Corporation

Data source

Data managed and maintained in an internal data management system by Sydney Water Corporation’s Operations Division (Systems Assurance).

Data provider

Sydney Water Corporation.

Method

The number represents the total volume of treated wastewater discharged to the sea, based on flow meter readings from wastewater treatment plants and water recycling plants managed by Sydney Water Corporation.

The flow of wastewater from the 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 is stored within an internal data management system. Adjustments are made to the data (if necessary) to correct any interruptions, errors and so on. Data have been extracted for 2009–10 from the data management system.

Uncertainty

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

Approximations, assumptions, caveats/limitations

Nil.

National Water Account 2010