Canberra
9.9 Discharge from urban water system

Supporting Information

(1) Overall

This line item is made up of several components. When capacity is available, treated water is transferred from Mount Stromlo Water Treatment Plant into Googong Reservoir via the water reticulation network. In addition to this there are two wastewater treatment plants (WWTPs) within the Canberra region that discharge treated water into the Molonglo River: the Lower Molonglo Water Quality Control Centre (LMWQCC) upstream from the Confluence with the Murrumbidgee, and the Queanbeyan WWTP upstream of Lake Burley Griffin. Only the LMWQCC and the Queanbeyan WWTP discharged treated wastewater to the surface water store.

The following table contains a breakdown of the volume of water discharge to surface water at each WWTP and the volume of water transferred to the Googong Reservoir.

Volume of treated water discharged to surface water in the Canberra region
  Plant  Volume treated (ML) 
Non-potable  Lower Molonglo Water Quality Control Centre 32,243
Queanbeyan Wastewater Treatment Plant 2,654
   
Subtotal 34,897
Potable  Mount Stromlo Water Treatment Plant 4,365
   
Subtotal  4,365
 Total
39,262


(2) ActewAGL – Potable water discharge

Under the urban water utility water access entitlement, ACTEW abstracts water from the regulated storages of Bendora and Cotter reservoirs, and the unregulated system of the Murrumbidgee River and transfers this water to Mount Stromlo Water Treatment Plant. If capacity is available, it is also possible to transfer treated water from Mount Stromlo Water Treatment Plant into Googong Reservoir via the water reticulation network.

(3) ActewAGL and Queanbeyan City Council – Treated wastewater discharge

The previous table provides a breakdown of the volume of wastewater discharge to surface water at each WWTP in the Canberra region for the 2010–11 year. Only the Lower Molonglo Water Quality Control Centre and the Queanbeyan WWTP discharged treated wastewater to the surface water store.

Quantification Approach

(1) ActewAGL – Potable water discharge

Data Source

ActewAGL Water Data Warehouse.

Provided by

ActewAGL.

Method

ActewAGL's flow meter measures the release from the water distribution system to Googong Reservoir.

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

Derived from measured data. Estimated uncertainty is +/– 5%.

 

(2) ActewAGL – Treated wastewater discharge

Data Source

ActewAGL Water Data Warehouse.

Provided by

ActewAGL.

Method

Treated wastewater discharged to the surface water store was measured by WWTP outflow flow meters. The 2009–10 discharge volume was extracted from the ActewAGL Water Data Warehouse. The Lower Molonglo Water Quality Control Centre is the only ActewAGL WWTP that discharges treated wastewater to the surface water store. Fyshwick WWTP has not been included in this line item, as discharges from this facility are directed back to the wastewater system or to the recycled water system.

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

Derived from measured data. Estimated uncertainty is +/– 5%.

(3) Queanbeyan – Treated wastewater discharge

Data Source

Queanbeyan City Council (QCC) database.

Provided by

QCC.

Method

Treated wastewater discharged to the surface water store was measured by WWTP outflow flow meters. The 2009–10 discharge volume was extracted from the QCC database. The Queanbeyan WWTP is the only QCC WWTP that discharges treated wastewater to the surface water store.

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

Derived from measured data. Estimated uncertainty is +/– 5%.

Comparative year

This line item corresponds to line item 13.7.1 Storages entitlement system, reported in the 2010 Account.  For the 2010 Account the volume reported was 29,122 ML.