Transgrid has recently published a Project Assessment Conclusions Report (PACR) for managing risk on Line 9677/1 (Canberra-Queanbeyan). Publication of this PACR represents the final step in the Regulatory Test for Transmission (RIT-T) process.
Commissioned in its current arrangement in 1969, Line 977/1 spans a route of 54km. The line is comprised of 282 structures: 278 single circuit wood pole structures between Structure 5 and Queanbeyan; and a short section where it runs as a double circuit with Line 976/1 outside Canberra substation between Structure 1 and Structure 4. Line 977/1 mainly traverses through agricultural land on the outskirts of Canberra in both the ACT and NSW.
Condition assessments performed through our routine maintenance program between 2017 and 2021 identified several condition issues on Line 977/1. A significant proportion of the wood pole structures are impacted by various levels of deterioration and corrosion. The affected components include wood poles, insulators, crossarms, conductor fittings, earthwire fittings and pole guys.
Wood pole deterioration greatly increases the likelihood of structure failure, which leads to conductor drop and presents consequent safety and bushfire risk to our personnel and the public, as well as resulting in reactive maintenance costs to repair the failed elements. While this is the case for any deteriorated elements of the transmission network, the bushfire risks are elevated for Line 977/1 as the line traverses sections of bushland, ACT Forestry, rural agricultural areas in the outer ACT and NSW surrounding areas. As asset conditions deteriorate over time, the likelihood of failure and subsequent risks will increase should these issues not be addressed.
Transgrid manages and mitigates bushfire and safety risks to ensure they are below tolerance levels or ‘As Low As Reasonably Practicable’ (‘ALARP’), in accordance with Transgrid’s obligations under the New South Wales Electricity Supply (Safety and Network Management) Regulation 2014 and Transgrid’s Electricity Network Safety Management System (ENSMS). The proposed investment will enable Transgrid to continue to manage and operate this part of the network to a safety and risk mitigation level of ALARP.
In the PSCR Transgrid presented one credible network option that would meet the identified need from a technical, commercial, and project delivery perspective. The optimal commercially and technically feasible option presented in this PACR – Option 1 (replace wood pole structures that are known to be degraded and deteriorated transmission line components) – is the preferred option to meet the identified need at this stage of the RIT-T.
No submissions were received in response to the PSCR during the consultation period which closed in January 2024 and no additional credible options have been identified.
Option 1 remains the preferred option at this stage of the RIT-T process. The estimated capital cost of this option is approximately $12.1 million +/- 25 per cent. Transgrid is the proponent of the proposed network project.
In accordance with the requirements of the Rules, a summary of the Project Assessment Conclusions Report is made available on the AEMO website. A copy of the PACR can be obtained from Transgrid’s website or by emailing regulatory.consultation@transgrid.com.au.