Transgrid has published the Project Specification Consultation Report (PSCR) for managing risk on Line 11 (Dapto-Sydney South). Publication of this PSCR represents the first step in the Regulatory Test for Transmission (RIT-T) process.
Line 11 is a single circuit steel tower 330 kV transmission line between Dapto and Sydney South substations, with a route length of 68km. There are 154 structures on this single circuit line including 129 suspension towers and 25 tension towers. The line is a key link in the Sydney South coastal region, and its route traverses urban areas near the substations, bushland in the Illawarra Escarpment, Sydney Water Catchment and National Park areas and also crosses the Princes Motorway (M1) at several locations.
Detailed analysis of asset condition information indicates that almost all suspension structures and/or other components on Line 11 have condition issues of some form (structure and conductor) including grillage deterioration which increase the probability of asset failure. This presents a bushfire and safety risk which Transgrid is obligated to manage. The proposed investment will enable us to continue to manage and operate this part of the network to a safety and risk mitigation level of ‘As Low As Reasonably Practicable’. Consequently, it is considered a reliability corrective action under the RIT-T.
Two credible network options have been identified that meet the underlying need from a technical, commercial, and project delivery perspective. Option 1 involves the replacement of 43 suspension structures, replacement of insulators, and refurbishment of assets, and has a capital cost of $39.95 million ($2024-25). Option 2 involves the replacement of 98 suspension structures, replacement of insulators, and refurbishment of assets, and has a capital cost of $69.32 million ($2024-25). Option 1 has been identified as the preferred option that maximises net benefits to participants in the National Electricity Market (NEM).
Transgrid welcomes written submissions on materials contained in this PSCR. Submissions are due on 15 July 2025.
In accordance with the requirements of the Rules, a summary of the Project Specification Consultation Report is made available on the AEMO website. A copy of the PSCR can be obtained from Transgrid’s website or by emailing regulatory.consultation@transgrid.com.au.