South East Queensland
11.4 Wastewater collected

Supporting information

The volumetric value for the line item at the end of the 2011–12 year was 246,055 ML.

This line item consists of the wastewater collected by the wastewater collection system within the South East Queensland (SEQ) region. As data were not available for line item 11.7 Stormwater ingress and line item 11.8 Infiltration from groundwater to urban water system and the only data available for this line item was wastewater treatment plant (WWTP) inflow, this line item actually represents WWTP inflow as a proxy for wastewater collected. The overestimation for this line item is offset by the under estimation for line item 11.7 Stormwater ingress and line item 11.8 Infiltration from groundwater to urban water system.

 

Wastewater treatment plant inflow by urban utility
Council/Water Utility

Volume (ML)

Gold Coast City Council

53,103

Logan City Council

22,761

Redland City Council

11,120

Queensland Urban Utilities

131,007

Unitywater

28,064

Total

246,055

Quantification approach

Data source

Qldwater: Statewide Water Information Management (SWIM) data (WA18: Total volume sewage collected) for Queensland Urban Utilities and Unitywater regions.

Redland City Council, Gold Coast City Council and Logan City Council provided annual WWTP inflow data for their regions.

 

Provided by

Bureau of Meteorology.

Method

Most of the individual discharges into the wastewater collection system are not metered and data on trade waste discharges were not available. Metered data for inflow into the WWTPs were available and  were used to populate this line item. If data for line item 11.7 Stormwater ingress and line item 11.8 Infiltration from groundwater to urban water system from groundwater were available, this would have been removed from the WWTP data to estimate wastewater collected by the wastewater collection system. As data were not available for these line items, the wastewater collected was assumed to be the entire WWTP inflows.

Assumptions, limitations, caveats and approximations

Including all WWTP inflow in this line item has resulted in an over estimation of wastewater collection, expected to be in the order of around 20 – 60 %. The over estimation for this line item is offset by the under estimation for line item 11.7 Stormwater ingress and 11.8 Infiltration from groundwater to urban water system. With the development of methods for calculating stormwater ingress and groundwater infiltration the WWTP inflow represented in this line item in the 2011 Account may be split across line item 11.4 Wastewater collected, 11.7 Stormwater ingress and 11.8 Infiltration from groundwater to urban water system.

Uncertainty information

The uncertainty estimate was not quantified.

Comparative year

Wastewater collected was reported according to WWTPs in 2011 Account but in 2012 Account data are provided Council wise.