10.10 Discharge from urban water system to groundwater
This line item volume (1,668 ML) represents the total volume of treated wastewater infiltrated to groundwater from the Kwinana Wastewater Treatment Plant during the 2011–12 year.
Treated wastewater from the Kwinana treatment plant is infiltrated to the groundwater store to assist in maintaining environmental values at the Spectacles Wetlands on the Swan Coastal Plain. The groundwater in this region is also extracted and recycled by Alcoa as part of the overall allocation of groundwater in the region.
Treated wastewater from the Kwinana Wastewater Treatment Plant is infiltrated to the groundwater store via infiltration ponds. The volume of treated wastewater infiltrated to groundwater is based on metered data at the treatment plant that is collected on an almost continuous basis.
Assumptions, limitations, caveats and approximations
Expected error for water meters is +/– 5%.
The Department of Water requires that all water meters, when tested under in situ conditions, must be within 5% accuracy across the full flow rate range (Guidelines for water meter installation 2009).
This line item corresponds to line item '10.10 Urban water discharge to groundwater' reported in the 2011 Account.