South East Queensland
9.9 Discharge from urban water system

Supporting information

a. Overview

The volumetric value for the line item at the end of the 2011–12 year was 62,517 ML.

This line item consists of urban water supply system (including potable and non-potable water), wastewater collection system and recycled water supply system discharges to surface water within the South East Queensland (SEQ) region.

Urban water supply system discharges

Discharges from the urban water supply system could not be quantified in a way that is complete, neutral and free from material error, but are expected to be minor compared to wastewater and recycled water discharges. Discharges may include supply system flushing, air valve releases and tank cleaning.

Wastewater collection system discharges

A number of wastewater treatment plants (WWTPs) discharge treated wastewater to rivers and creeks within the SEQ region. This line item includes discharges to freshwater rivers and creeks that form part of the surface water system. Discharges to estuarine rivers, creeks, inlets and the sea are reported in line item 19.7 Wastewater discharge outside of region. A number of WWTPs that discharge to the Brisbane River are included in line item 19.7 Wastewater discharge outside of region, as the Brisbane River is estuarine through much of the urban Brisbane area.

Recycled water supply system discharges

Reverse osmosis brine concentrate from the Bundamba advanced water treatment plant was discharged to the Bremer River as part of the Western Corridor Recycled Water Scheme treatment process.

Excess purified recycled water discharges occurred from the Gibson Island and Luggage Point advanced water treatment plants, but as the Brisbane River is estuarine at the discharge point, these discharges were reported in line item 19.7 Wastewater discharge outside of region. No excess purified recycled water discharges to surface water occurred from Bundamba advanced water treatment plant.

There is potential for recycled water discharges from the Western Corridor Recycled Water Scheme to Lake Wivenhoe in accordance with the current SEQ System Operating Plan when SEQ water grid storages fall below 40%. When the total volume of water stored by key water grid storages falls below 40% of the total water storage capacity of these storages, the supply of purified recycled water to Lake Wivenhoe from the Western Corridor Recycled Water Scheme is to be maximised, subject to appropriate approvals from Queensland Department of Natural Resources and Mines (DNRM). If and when purified recycled water is introduced into Lake Wivenhoe, this water will then be available for use throughout the entire SEQ region via the SEQ water grid.

 

Wastewater and recycled water discharges to surface water
Discharge description

Volume (ML)

Treated wastewater discharge

                       61,705

Excess recycled water discharge

0

Reverse osmosis concentrate discharge

                           812

Total SEQ region

                       62,517

 

Quantification approach

Data source

Queensland Department of Science, Information Technology, Innovation and Arts (DSITIA): licensed discharge data from the Point Source Database.

Seqwater: Western Corridor Recycled Water Scheme dataset.

 

Provided by

Bureau of Meteorology.

Method

Wastewater collection system discharges

Annual waste water treatment plant (WWTP) discharge volumes obtained from DSITIA's Point Source Database. Each WWTP discharge point was then identified and WWTP that discharge to surface water were selected and summed.

Recycled water supply system discharges

Annual advanced wastewater treatment plant discharge data for reverse osmosis concentrate was obtained from Seqwater datasets for Bundamba advanced wastewater treatment plant.

 

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The uncertainty was not quantified.