The volume recognised in the water accounting statements (208,934 ML) represents the volume of wastewater discharged from the Melbourne region to Port Phillip Bay and Bass Strait.
The table below shows the breakdown of wastewater discharge for each treatment plant by water utility in the Melbourne region during 2009–10.
| Utility | Discharge location | Volume (ML) |
|---|---|---|
| Melbourne Water | Western Treatment Plant discharge to Port Phillip Bay |
93,663 |
| Eastern Treatment Plant discharge to Bass Strait |
102,627 |
|
| Melbourne Water subtotal |
196,290 |
|
| City West Water | Altona Sewage Treatment Plant (STP) discharge to Port Phillip Bay |
4,584 |
| City West Water subtotal |
4,584 |
|
| South East Water | Somers STP discharge to South East Outfall |
1,154 |
| Mt Martha STP discharge to South East Outfall |
4,273 |
|
| Boneo STP discharge to South East Outfall |
2,633 |
|
| South East Water subtotal |
8,060 |
|
| Total |
208,934 |
Melbourne Water: Waterworks database.
City West Water: supervisory control and data acquisition (SCADA) database.
South East Water: various internal sources.
Melbourne Water, City West Water and South East Water.
The total volume of wastewater discharge out of the region is the sum of a number of components that are provided from different water utilities as described below.
Melbourne Water
This item represents the sum of the volume of wastewater discharge to sea (including Port Phillip Bay) from Melbourne Water’s Western Treatment Plant and Eastern Treatment Plant.
City West Water
This item represents the daily metered volume of treated wastewater discharged from the Altona wastewater treatment plant to Port Phillip Bay. The line item was calculated by deducting the metered volume of water used in-process within the treatment plant from the metered wastewater discharge value.
South East Water
This item represents the daily metered volume of treated wastewater discharged to the sea via the South East Outfall.
Melbourne Water: Determined using a mass balance approach of all wastewater collected, treated, stored and recycled. Uncertainty is ungraded.
City West Water: Derived from metered data. Estimated uncertainty is +/–5%.
South East Water: Derived from metered data. Estimated uncertainty is +/–5%.
Uncertainty values provided by City West Water and South East Water refer to the Essential Services Commission’s standard confidence grades, as detailed in its June 2005 guideline for Approving, Conducting and Reporting Audits for Victorian Water Businesses (ESC 2005). Refer to Summary Audit Report – Regulatory Audit of AGL Energy Limited, October 2010 (ESC 2010) prepared individually for Yarra Valley Water and South East Water.
Nil.
National Water Account 2010
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