Melbourne
9.9 Discharge from urban water system

Supporting information

The volume presented (26,243 ML) represents the treated wastewater discharged to surface water from Western Water's recycled water plants (RWPs) and Yarra Valley Water's local treatment plants (LTPs), and recycled water provided from the Melbourne Water Western Treatment Plant as environmental flows to the Lake Borrie wetlands.

The breakdown of treated wastewater discharged to surface water in the Melbourne region during the 2012–13 year is presented in the following table.

Wastewater discharge
Authority Discharge location Volume (ML)
Western Water Bacchus Marsh RWP to Land lot/lagoon 141
Gisborne RWP to Jacksons Creek 488
Melton RWP to Werribee River 878
Riddells Creek RWP to Riddells Creek 97
Romsey RWP to Deep Creek 280
Sunbury RWP to Jacksons Creek 1,256
Subtotal for Western Water 3,140
Yarra Valley Water Brushy Creek LTP to Brushy Creek 3,245
Craigieburn LTP to Merri Creek 395
Healesville LTP to Yarra River 319
Upper Yarra LTP to Yarra River 739
Lilydale LTP to Olinda Creek 1,767
Monbulk LTP to Sassafras Creek 18
Wallan LTP to Merri Creek 204
Subtotal for Yarra Valley Water 6,687
Melbourne Water Recycled water to Lake Borrie wetlands
16,416
Total  26,243

Quantification approach

Melbourne Water

Data source

Supervisory control and data acquisition (SCADA) database.

Provided by

Melbourne Water.

Method

Water recycled and used for conservation flows is metered using an ultrasonic level transmitter. This recycled water is measured by Melbourne Water before being discharged to the Lake Borrie wetlands (Ramsar-listed).

Assumptions, limitations, caveats and approximations

Data are logged daily and reported quarterly, and thus metering periods align with the reporting year.

Uncertainty information

Ultrasonic level transmitters are used to measure flows and are assumed to have an accuracy of +/–5 to +/–10%.

Western Water

Data source

RWP data.

Provided by

Western Water.

Method

Meters are located at the outlet of the treatment plants and are read daily by the treatment plant operators. 

Assumptions, limitations, caveats and approximations

Excludes discharge at Woodend RWP to Five Mile Creek, as this is not located within the Melbourne region.

Uncertainty information

The uncertainty is estimated to be +/– 5% based on meter specifications.

Yarra Valley Water

Data source

BI reporting system, treatment plant, and trade waste dashboard and Flow and reuse summary report.

Provided by

Yarra Valley Water.

Method

Meters measuring the volume of treated wastewater discharged from local treatment plants to surface water are read daily.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The uncertainty is estimated to be +/– 5% based on meter specifications.