Sydney

20.4.1 Discharge of urban wastewater to connected surface water

Supporting information

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.

Plant operator and description of wastewater discharge	Plant	Discharging to watercourse	Volume discharged during 2009–10 (ML)
Goulburn Mulwaree Council—treated wastewater from wastewater treatment plants	Goulburn and Marulan	Not applicable	0*
Lithgow City Council—treated wastewater from wastewater treatment plants	Lithgow	A tributary of the Coxs River	1,516
	Wallerawang	Coxs River	218
Palerang Council—treated wastewater from wastewater treatment plants	Braidwood	A tributary of the Shoalhaven River	79
Shoalhaven City Council—treated wastewater from wastewater treatment plants	Berry	Broughton Creek	149
	Bomaderry	Abernathys Creek	927
	Nowra	Shoalhaven River	1,666
Sydney Water Corporation—treated wastewater from water recycling plants	Castle Hill	Cattai Creek	2,645
	Glenfield	Georges River	101
	Liverpool	Georges River	1,361
	Penrith	Boundary Creek	8,356
	Picton	Stonequarry Creek	0**
	Quakers Hill	Breakfast Creek	11,369
	Richmond	Rickabys Creek	223
	Rouse Hill	Second Ponds Creek	3,513
	St Marys	South Creek	7,999
	West Camden	Matahil Creek	1,126
Sydney Water Corporation—treated wastewater from wastewater treatment plants	Brooklyn	Hawkesbury River	75
	Fairfield	Orphan School Creek	872
	Hornsby Heights	Calna Creek	2,106
	North Richmond	Redbank Creek	292
	Riverstone	Eastern Creek	600
	Wallacia	Warragamba River	211
	West Hornsby	Waitara Creek	4,520
	Winmalee	Nepean River	6,465
Wingecarribee Shire Council—treated wastewater from wastewater treatment plants	Berrima	Olbury Creek	78
	Bowral	Wingecarribee River	1,127
	Braemar	Iron Mines Creek	785
	Bundanoon	Reedy Creek	303
	Moss Vale	Whites Creek	793
Total			59,475

* 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

Wastewater treatment plants releasing treated water	Reservoir receiving treated water	Wastewater treatment plant operator	Reservoir managing authority
Lithgow	Lake Lyell	Lithgow City Council	Delta Electricity
Wallerawang	Lake Wallace	Lithgow City Council	Delta Electricity
Berrima, Bowral, Braemar and Bundanoon	Lake Burragorang (Warragamba Dam)	Wingecarribee Shire Council	The Sydney Catchment Authority
Moss Vale	Medway	Wingecarribee Shire Council	Wingecarribee Shire Council
Braidwood	Lake Yarrunga (Tallowa Dam)	Palerang Council	The Sydney Catchment Authority

Quantification approach

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.