Canberra

This line item refers to an estimate of the total ingress of water into the Lower Molonglo Water Quality Control Centre. The volume was calculated by the Bureau of Meteorology using data obtained from ActewAGL.

Data source

ActewAGL: sewer gauging and rainfall records in Hydstra.

Data provider

ActewAGL.

Method

Lower Molonglo Water Quality Control Centre

Base-flow calculations were used to assess infiltration to the Lower Molonglo Water Quality Control Centre (LMWQCC) during 2009–10 using rainfall records for the same time period.

A typical week with no rainfall (09–15 November 2009) was chosen to represent the base-flow conditions into LMWQCC. In this week, inflows were 555.7 ML. This flow rate was multiplied by 52 weeks to represent the total base-flow inflows to LMWQCC for the reporting year. This value was then subtracted from the total inflow to LMWQCC to give an estimate of the ingress of stormwater to the sewer (including any groundwater ingress where the water table has risen due to wet weather).

The total inflows were calculated as shown in the following table.

Uncertainty

Ungraded.

Assumptions, approximations and caveats/limitations

• The reported volume relates to the ingress into Canberra wastewater system only. Ingress into Queanbeyan sewerage system is unknown.
• This value is net volume of infiltration minus leakage and based on broad assumptions. It does not take into account groundwater ingress during dry weather, or discharge to groundwater as part of the base flows.