TasNetworks has published the Project Assessment Conclusion Report (PACR) for Managing risk on the George Town – TEMCO (GT-TE) transmission line. Publication of this PACR represents the final step in the Regulatory Investment Test for Transmission (RIT-T) process.
The GT-TE 110 kV transmission line was constructed in 1962 to supply the TEMCO (now Liberty Bell Bay) manganese processing plant. The 3.1 km line consists of steel lattice towers supporting mainly aluminium conductor steel reinforced conductors, with a short section of the original 19/.116 hard drawn copper conductors.
During recent condition assessments performed through our routine maintenance program, numerous corrosion issues were identified on the GT-TE transmission line. These conditions have been attributed to the costal location of the line, the exposure of the line to industrial pollution and the total breakdown of the structure’s protective coatings.
The corrosion issues on the GT-TE line serve to increase the probability that one of the structures of the line will fail and, as these assets continue to age, this probability will continue to increase. The GT-TE line is the only source of supply to the Liberty manganese alloy processing plant at Bell Bay, meaning its failure would result in significant volumes of unserved energy. Further, the line traverses areas of bushland and, as such, in the event of a failure of the line’s structure there is the potential for the ignition of a bushfire.
Addressing the condition issues of the GT-TE line will enable us to manage reliability and other risks in the George Town area. TasNetworks expects that addressing these issues will result in significant market benefits and, as such, we consider the identified need for this investment to be market benefits under the RIT-T.
We considered there were four credible options from a technical, commercial, and project delivery perspective that could be implemented in sufficient time to meet the identified need. This PACR has found that Option 4 is the preferred option at this stage of the RIT-T (consistent with the draft conclusion in the earlier Project Specification Consultation Report (PSCR)).
Option 4 involves completely replacing the existing 110kV transmission line. Specifically, a new double circuit 110kV transmission line will be constructed within the existing corridor to TasNetworks’ design standards. This standard design uses double circuit steel pole support structures with conductor strung at 75°C.
The estimated capital expenditure associated with Option 4 is $5.6 million (in 2023/24 dollars). On a weighted basis, Option 4 is found to deliver net benefits of approximately $70.2 million. The works are estimated to take 24 months to complete with project completion expected in 2026/27.
No submissions were received in response to the PSCR during the consultation period which closed in October 2024 and no additional credible options have been identified.
In accordance with the requirements of the Rules, a summary of this PACR is made available on the AEMO website. A copy of the PACR can be obtained from either the TasNetworks website or by emailing our regulation team via regulation@tasnetworks.com.au.