Powerlink has recently published a ‘Project Assessment Conclusions Report’ (PACR) “Maintaining reliability of supply in the Cairns region Stage 1, Addressing the condition risks of the transmission towers between Davies Creek and Bayview Heights.”
The majority of supply to the Cairns region is delivered through the inland 275kV network to Ross, near Townsville. From Ross it is transferred via a 275kV transmission line to Chalumbin, continuing via a second 275kV transmission line from Chalumbin to the Woree Substation on the outskirts of Cairns. These 275kV transmission lines also provide connections to the Mt Emerald Wind Farm and Kareeya Power Station.
Emerging condition risks due to structural corrosion on the 275kV transmission lines between Ross, Chalumbin and Woree substations puts at risk Powerlink’s ongoing compliance with the reliability and service standards set out in the National Electricity Rules (the Rules), Powerlink’s Transmission Authority and applicable regulatory instruments. Given the non-homogenous condition of the transmission structures over the 348km transmission line route, Powerlink is applying a prudent and staged approach to address higher risk components in the nearer term based on deteriorating condition.
The final 16km of the Chalumbin to Woree section of the transmission line, between Davies Creek and Bayview Heights, traverses the environmentally sensitive World Heritage Wet Tropics area terminating near Trinity Inlet Marine Park, and has required a comprehensive ongoing maintenance program due to its heightened exposure to highly corrosive coastal winds. The condition of the steel lattice towers in this section of the line requires priority action to address their more complex and advanced condition risks (Stage 1).
In March 2021 Powerlink published a ‘Project Specification Consultation Report’ (PSCR) identifying the proposed preferred option to address the risks and claiming exemption from producing a ‘Project Assessment Draft Report’ as allowed for under NER Clause 5.16.4(z1).
There were no submissions received in response to the PSCR, which closed in July 2021. As a result, no additional credible options that could deliver a material market benefit have been identified and the outcomes of the economic analysis contained in the PACR remain unchanged from those published in the PSCR.
The PACR recommends implementation of Option 2 which involves the refurbishment of the 37 towers through the selective replacement of corroded members and components, along with the painting of all 37 towers by December 2023. The indicative capital cost of the RIT-T project for the preferred option is $38.37 million in 2020/21 prices. Powerlink is the proponent of this network option.
Under Option 2, consultation and joint planning with Wet Tropics’ stakeholders will be undertaken in late-2022, with contractors deployed to site in 2022/23 and work completed by December 2023.
In accordance with the requirements of the Rules, a summary of the PACR has been made available on AEMO’s website. A copy of the PACR can be obtained from the Powerlink Website on the RIT-T Consultations page or by emailing networkassessments@powerlink.com.au.
Any enquiries in the first instance should be directed to:
Roger Smith
Manager Network and Alternate Solutions
Powerlink Queensland
PO Box 1193
VIRGINIA, QLD 4014
Tel: (+617) 3860 2328