Page 4214 - Week 12 - Thursday, 1 December 2022
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9. Bureau of Meteorology water balance and water outlook models of the ACT predict that deep soil moisture content reached 30-year record high levels in 2021-2022. Inflows to LMWQCC historically reflect the deep soil moisture and have also seen record high inflows in late 2022.
Inflow and Infiltration (I&I) is a characteristic of all sewerage networks. Icon Water monitors industry best practice in identifying the levels of I&I within the network and assessing where it is economically viable to institute remedial works to actively target I&I. Specifically, Icon Water uses sewer gauging to identify catchments with the largest proportional flow to the services population which allows a targeted I&I reduction approach. Flow monitoring at sewer pump stations has also been utilised in this space to consider broader sewer catchment impacts. Individual inspections of existing backflow devices around the network have been undertaken to accelerate maintenance of these assets if required.
Icon Water has an extensive sewer flow gauging network across Canberra, which allows not only the monitoring of network demand over time but also the breakdown of demand from different areas of the city. The gauging network is a key tool in being able to track network performance trends over time. With regards to I&I, this allows Icon Water to analyse the system response to rainfall and assess performance against industry benchmarked metrics. More targeted network interventions and maintenance activities across smaller catchment areas can then be conducted to address I&I issues when they occur.
Icon Water’s sewerage network has historically had low rates of I&I due to its relatively young network age. Implementing additional cost-effective controls in this space is difficult as I&I identification and remediation works have high costs attached and small defects in the network can be numerous and very difficult to locate accurately. Other than the I&I management techniques mentioned above, Icon Water’s overall maintenance and targeted renewals programs also provide benefits of managing this issue. During the 2018-2023 regulatory period Icon Water will have renewed approximately 50 kilometres and cleaned or inspected approximately 1,400 kilometres of sewer mains. Additionally, Icon Water will have completed approximately 900 targeted localised sewer main repairs on reticulation, branch lines and service connections.
10. As noted in the response to question 1, LMWQCC’s original design capacity was 270,000 EP which was intended to be augmented in three stages to an ultimate capacity of 1,000,000 EP. In 2010, LMWQCC was augmented, increasing its treatment capacity to 100 megalitres per day which is equivalent to approximately 550,000 EP. Icon Water have several projects underway to further augment this capacity to cater for approximately 790,000 EP. These projects are planned for construction during the 2023 – 2028 regulatory period.
Icon Water has also recently completed a review of its Wastewater System Strategy which considers infrastructure required to support long term population growth over a 50-year planning horizon.
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