South East Queensland
11.4 Wastewater collected
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 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.
|Urban utility||Wastewater treatment plant (WWTP)|| Volume
|Queensland Urban Utilities||Aratula||19|
|Total Queensland Urban Utilities||149,183|
|Total SEQ region||269,214|
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 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 overestimation of wastewater collection, expected to be in the order of around 20–60%. The overestimation for this line item is offset by the underestimation for line item 11.7 Stormwater ingress and line item 11.8 Infiltration from groundwater. 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, line item 11.7 Stormwater ingress and line item 11.8 Infiltration from groundwater in future accounts.
The uncertainty estimate was not quantified.
This line item was not included in the 2010 Account as retail customers of the urban water system were considered to be part of the urban water system. The supply of urban water to, and collection of wastewater from, these retail customers was considered to be a within store flow and was not included in the 2010 Account water accounting statements.
Wastewater collected was included in the Urban water region note of the 2010 Account. The volume reported in this note of 212,085 ML has been included in the 2011 Account as the comparative year volume for this line item.