Sydney
11.12 Allocation diversion of surface water to urban water system

The following tables provide a summary and breakdown of the allocation diversion of flows by urban water utilities in the Sydney region.

The previous table is based on supply records of the bulk supplier, SCA. However, the water receivers, in the form of the Shoalhaven City Council, Sydney Water Corporation and Wingecarribee Shire Council, record differences in received volumes. The differences have been attributed to limits in meter accuracy. In order to maintain consistency in calculations, the previous table, as well as the accounting statements, show the volumes recorded by the bulk supplier.

The Fish River Water Supply Scheme delivered 506 ML to Lithgow City Council's distribution system within the Sydney region. This volume was not diverted from surface water sources in the Sydney region. Therefore, it is not included in the previous table, but instead included in line item 11.9 Delivery of water to urban system under inter-region agreement.

Diversions to the water treatment plants (WTPs) were measured at the plants. At Goulburn WTP, inflow from the plant was measured using a flow meter.

The volume is based on metered data. Estimated accuracy based on meter accuracy and professional judgment is +/– 20%.

The flow diverted from Farmers Creek No. 2 Reservoir to Oakey Park WTP was measured by the height of the water over the weir in the channel at the inlet works at the WTP. There is a direct pipeline connection between the storage and the WTP. The outflow from the WTP was measured by an ABB Magflow meter.

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%. Meters are calibrated annually by ABB (meter supplier).

Full-bore magnetic flow meters and ultrasonic flow meters were used to measure water diversions to urban utilities.

There are minor differences in the supplied volumes recorded by the SCA and its recipients. In order to maintain consistency, the values provided by the SCA have been used for this line item.

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

Volumes were derived from ABB Magflow meter data received through the SCADA system and transferred into spreadsheets.

The quantification method used in this note only applies to the council's water diversions from Medway and Bundanoon storage reservoirs to their respective WTPs. Supplies to the council's Wingecarribee WTP are made by the SCA.

The volume is based on measured data. Estimated accuracy based on meter accuracy is +/– 7%. External flow verification audits for the flow meters are conducted annually by Hydrometric Consulting Services.

The following table compares the value at 30 June 2010 reported in this account with the corresponding value reported in the 2010 Account.