Transgrid has recently published a Project Assessment Conclusions Report (PACR) for managing safety and environmental risks on Line 18 (Kangaroo Valley – Dapto).
Commissioned in 1974, the 43 km single circuit 330 kV transmission line is comprised of 107 steel tower structures between Kangaroo Valley switching station and Dapto 330 kV substation. The section from Kangaroo Valley to Robertson was built in 1974 whilst the remaining section to Dapto substation was built in 1962, previously part of a Yass-Dapto connection. Line 18 forms a key link between the Shoalhaven and Wollongong regions and supports the transmission of electricity from existing generators in southern NSW to the major load centres of Sydney, Newcastle and Wollongong.
The line will continue to play a central role in supporting the flow of energy to take advantage of naturally diverse weather patterns, and in the safe and reliable operation of the power system throughout and after the transition to a low-carbon electricity future.
The transmission line mainly traverses farmland and Morton National Park – after leaving Dapto, it climbs from the coastal plain up the Illawarra Escarpment.
Condition issues that will impact the safe and reliable operation of the network have been found on Line 18. The condition issues raise a number of risks associated with asset failure, including safety and environmental (bushfire) risks. Investment to address the deterioration of the assets along Line 18 due to corrosion is needed to mitigate risks to safety and the environment.
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. Consequently, it is considered a reliability corrective action under the RIT-T.
Transgrid published a Project Specification Consultation Report (PSCR) In May 2021. Transgrid invited written submissions on the materials contained within the PSCR and received one submission which covered consideration of the maintenance regime, assessment of the risk costs, and demonstrating the value for money of the investment. Transgrid values the feedback raised in the submission and has taken it into account in preparing this report.
No additional credible options were identified during the consultation period following publication of the PSCR. The following changes have occurred since the PSCR which have not made an impact on the preferred option:
- The cost estimate factors for Option 1 have been adjusted to reflect the latest estimated resourcing requirements to implement the preferred option. This resulted in an increase to the total cost estimate from $8.66m to $8.83m.
- Financial risk costs have been included in the analysis in response to the submission received.
Option 1 (line refurbishment) remains the preferred option at this stage of the RIT-T process. This option is estimated to have a capital cost of $8.83 million +/- 25% and is expected to be completed in 2022/23. Transgrid is the proponent of the proposed network project.
In accordance with the requirements of the National Electricity Rules, a summary of the PACR is made available on the AEMO website. A copy of the PACR can be obtained from Transgrid’s website or by emailing RIT-TConsultations@Transgrid.com.au.