TransGrid has recently published a Project Assessment Draft Report for managing safety and environmental risks on Line 25 & Line 26 (Vineyard – Munmorah).
Lines 25 and Line 26 are two key 330 kV transmission lines from the Central Coast to Sydney. Spanning a route of 109 km, Line 25 connects Eraring substation on the Central Coast and Vineyard substation on the Greater Sydney network. Line 26 spans 123 km and runs between Munmorah substation on the Central Coast and Sydney West substation on the Greater Sydney network.
This RIT-T relates to single circuit section of Line 26, as well as the double circuit section of Line 25 and Line 26 between transmission Structure 11 and the Vineyard substation.
The transmission lines are part of the network that connects more than 4,000 MW of existing generators north of Sydney (Central Coast, Upper Hunter and northern NSW) and the major load centre of Sydney. They will continue to play a central role in supporting the flow of energy between regions 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.
Corrosion-related issues that will impact the safe and reliable operation of the network have been found on Line 25 and Line 26. The condition issues raise a number of risks associated with asset failure, including safety and environmental (bushfire) risks. As the asset condition deteriorates over time, the likelihood of failure and subsequent risks may increase should these issues not be addressed.
TransGrid published a Project Specification Consultation Report (PSCR) for managing safety and environmental risks on Line 25 and Line 26 in October 2018. No submissions were received in response to the PSCR during the consultation period which closed in January 2019.
TransGrid considered four credible options that would meet the identified need from a technological and project delivery perspective. Refurbishment of the line remains the most economical and preferred option at this stage of the RIT-T process.
At the time the PSCR was published, TransGrid’s cost estimate for the preferred option — refurbishing Line 25 and Line 26 — was primarily based on a desktop assessment of the activity required to refurbish the line.
TransGrid has since undertaken detailed inspections of the asset involving extensive climbing of every structure to further develop the scope. The inspections determined the quantum and extent of the condition issues has increased from TransGrid’s initial outline noted in the PSCR in October 2018.
Due to the issues described above, the cost estimate of refurbishing Line 25 and Line 26 in the PSCR ($6.7 million +/- 25 per cent) is not adequate to cover the scope of Option 1 and has been revised accordingly. As a result of the condition of the asset being further deteriorated than expected, the associated estimates proposed to remediate those issues has been revised to factor in:
- increase in identified condition issues and associated increase in the required scope of works
- revision of pricing rates to reflect the latest market conditions.
No additional credible options were identified during the consultation period following publication of the PSCR. TransGrid has recalculated the NPV analysis for this PADR using the updated estimate for capital expenditure and risk cost benefits for Option 1.
Option 1, refurbishing Line 25 and Line 26, remains the preferred option at this stage of the RIT-T process.
In accordance with the requirements of the Rules, a summary of the Project Assessment Draft Report is made available on the AEMO website. A copy of the Project Assessment Draft Report can be obtained from TransGrid Website on the Regulatory Investments Test page or by emailing RIT-TConsultations@TransGrid.com.au
Submissions in response to this Project Assessment Draft Report are required by the closing date of 10 March 2020.