Sydney

The volume of water discharged from urban wastewater systems during 2009–10 was 59,475 ML.

A breakdown of treated water from wastewater treatment plants and water recycling plants discharged to the streams is provided in the following table. The discharged volume is a decrease to the water distribution system store.

* 1,569 ML was received at the plants for treatment. All treated water was used for irrigation.

** During 2009–10, received wastewater was treated to produce recycled water for on-site and agricultural uses.

Wallerawang wastewater treatment plant receives wastewater generated from supplies made to the Lithgow City Council’s distribution system from the Fish River Water Supply Scheme. Lithgow wastewater treatment plant receives wastewater generated from supplies made to the distribution system from Oakey Park Water Treatment Plant. Wastewater received at these wastewater treatment plants includes inflow and infiltration resulting from stormwater.

Treated water released from some of the wastewater treatment plants included in the above table becomes inflow to downstream reservoirs as shown in the following table. (Line item 13.7.1 does not include these releases and, therefore, the volumes for the line items 20.4.1 and 13.7.1 are not equal.)

Treated water released from wastewater treatment plants received at reservoirs

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

Note a: Goulburn Mulwaree Council

Quantification approaches are not provided because the volume discharged was zero.

Note b: Lithgow City Council

Data source

Data spreadsheets.

Data provider

Lithgow City Council.

Method

Flows were measured by water channel and height sensors, and converting water level to a volume in a spreadsheet using a rating table.

Uncertainty

The volume was estimated from measured data. Uncertainty is ungraded.

Approximations, assumptions, caveats/limitations

Wastewater received at Lithgow and Wallerawang wastewater treatment plants includes inflow and infiltration resulting from stormwater, in addition to wastewater generated from potable water supplies made to the water distribution system. Therefore, all of these sources contribute to the volume of treated wastewater released from the plants to the streams.

Note c: Palerang Council

Data source

Database maintained as spreadsheets.

Data provider

Palerang Council.

Method

For 2009–10, the wastewater treatment plant (now decommissioned) did not have any dedicated flow measurement at the outlet. The outflow from the plant was from a tertiary pond system. Measurement was made at the inlet to the plant only and this was done by an ABB Magmaster-type flow meter. The inflow measured from the flow meter has been approximated to the outflow, disregarding any inflow that may be lost through evaporation, or that may be supplemented through rainfall or infiltration to the pond system.

Uncertainty

The volume was estimated from measured data. Estimated uncertainty based on meter accuracy and professional judgment is +/–10%.

Approximations, assumptions, caveats/limitations

Nil.

Note d: Shoalhaven City Council

Data source

• Shoalhaven City Council telemetry system.
• Daily data registers from the plant operations section.

Data provider

Shoalhaven City Council.

Method

Outflows from wastewater treatment plants were measured as follows:

• Berry wastewater treatment plant: Vega-type ultrasonic flow meter
• Bomaderry and Nowra wastewater treatment plants: a Parshall flume with a venturi flow meter at each site.

Uncertainty

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

Approximations, assumptions, caveats/limitations

Nil.

Note e: Sydney Water Corporation

Data source

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

Data provider

Sydney Water Corporation.

Method

The value represents the sum of total metered volume of treated wastewater discharge to surface water 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. The data is stored within a complex 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.

Note f: Wingecarribee Shire Council

Data source

Supervisory control and data acquisition (SCADA) data records from wastewater treatment plants.

Data provider

Wingecarribee Shire Council.

Method

The value represents the total volume of treated wastewater discharge to surface water from wastewater treatment plants.

The flow of wastewater from the plants was measured using ABB Magmaster flow meters installed on-site. The data from the flow meters are continually monitored and recorded.

Uncertainty

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

Approximations, assumptions, caveats/limitations

Nil.