Transmission Line 99M forms an approximate 73 km 132 kV single circuit connection between the Yass 330 kV substation and the Murrumburrah 132 kV substation, located in the Southern Tablelands region.

To facilitate the grid connection of the Coppabella Wind Farm development, Transgrid is proposing to rebuild an approximate 39 km section of Line 99M between the Coppabella Wind Farm (at Structure 143) and Yass substation as a double circuit line (the project).

The rebuilt section of Line 99M would comprise new 40 metre high steel or concrete pole transmission structures, which would be up to 20 meters higher than the existing wooden pole structures. The project would also involve the construction of a new switch bay and associated electrical and communications connection works at Yass substation.

Construction is expected to start in mid 2024.

Why is the work taking place?

Goldwind Pty Ltd. has received approval to construct and operate the Coppabella Wind Farm. The Coppabella Wind Farm would connect to the National Electricity Market via Transgrid’s Transmission Line 99M.

The current line rating of Line 99M was not sufficient to accommodate the proposed generation of the Coppabella Wind Farm. While the former approved project (July 2018) involved uprating the line by replacing the existing conductors, further network constraint studies determined that the line would still be constrained under certain operating conditions, particularly due to the introduction of new renewable generation sources in the region.

Additionally, the rebuild of Line 99M would address the marginal loss factor which would have been applied to the former approved transmission line uprating project by the Australian Energy Market Operator (AEMO).


Main REF

Transgrid prepared a Review of Environmental Factors (REF) under Part 5 of the Environmental Planning and Assessment Act 1979, which was made available for community and stakeholder comment between 13 June 2019 and 9 August 2019.

The project has now been determined. View the Review of Environmental Factors, Submissions Report and Decision Statement in the resources section.  

Addendum REF

An Addendum REF was prepared to seek approval for the installation of an additional transformer at Yass substation. This would support the grid connection of the Coppabella Wind Farm. The Addendum REF was publicly displayed on the Transgrid website between 3 August and 7 September 2020 for community and stakeholder comment.

The Addendum REF has now been determined. The Addendum REF, Submissions Report and Decision Statement can be viewed in the resources section

Addendum REF 2

An Addendum REF was prepared to seek approval for the installation of a static synchronous compensator (STATCOM) at Yass substation to meet the connection requirements of the Australian Energy Regulator and address network planning constraints due to the Coppabella Wind Farm grid connection. The STATCOM would be installed on the former switchyard bench, adjacent to the new 132/330 kV transformer compound. The Addendum REF was publicly displayed on the Transgrid website between 22 November to 22 December 2023 for community and stakeholder comment.

The Addendum REF has now been determined. The Addendum REF, Submissions Report and Decision Statement can be viewed in the resources section

Frequently Asked Questions

1. What is the Coppabella Wind Farm (CWF)?

The CWF is located in the Southern Tablelands of New South Wales approximately 30km west of Yass.

The NSW Government has approved construction and operation of up to 75 wind turbines and related civil and electrical infrastructure a part of the CWF.

Once operational, the wind farm production will power around 159,000 homes each year.

See here for the indicative project layout

2. Who is responsible for building and operating CWF?

CWF is owned by Goldwind Australia, who will be responsible for its construction and operation.

For more information or to contact the CWF via:

To enable the grid connection of CWF, an approximate 39km section of Line 99M (TL99M) is required to be rebuilt as a double circuit line. The rebuild of Line 99M is being carried out by Transgrid.

3. What is Transgrid? What is their role?

Transgrid owns and operates the high voltage transmission network in NSW and the ACT, with connections to Victoria and Queensland. Our network currently consists of over 13,000 km of high voltage transmission wires and 121 substations.

We are leading the transition to Australia’s clean energy future. The traditional coal system that served our country for decades is nearing the end of its life, to be replaced by wind and solar generation. 

4. Why does TL99M have to be rebuilt between CWF and Yass substation?

The current capacity of Line 99M does not meet the required rating to transmit the generation capacity of the CWF to the electricity network. Rebuilding 39km (approx.) section of Line 99M from the CWF site to Yass substation as a double circuit 132kV line will ensure the clean energy generated by the wind farm would be safely and reliably connected to the grid.

5. What does the planned rebuild of TL99M involve?

Rebuild transmission line 99M involves:

  • Replacing all existing wooden pole transmission structures between Yass 330 kV substation and the CWF ‘tie in’ point (Structure 143) near the CWF with new steel or concrete pole transmission structures up to 40m in height. The new poles would be up to 20m higher than the existing wooden pole structures.
  • Upgrading existing access tracks and installing new access tracks where required.
  • Constructing a new transformer bay switch bay and STATCOM at Yass substation.

6. When is construction due to start?

Construction is expected to start in mid-2024 and would take approximately 20 months to complete.

7. Is this project related to Humelink?

The 99M Rebuild is not part of the HumeLink Project. For more information on HumeLink please visit the HumeLink page.

8. What will the new transmission structures look like?

The new structures will be a either steel or concrete pole structures up to 40m high, like those shown on the next page.

For more images of the likely new structures please visit see REF Appendix F here.


Below: current view looking north-west from Black Range Rd

9. What is an easement?

To protect your safety and provide a safe, reliable network, we have easements over its transmission lines and underground cables.

Easements are also ‘rights of way’, giving our people and contractors access to our assets including towers and lines to build, operate and maintain infrastructure. We restrict certain activities on easements to protect the public and the assets themselves. Easements vary in width depending on the voltage and design of the infrastructure.

10. Would a new easement be needed for the Project?

The rebuild of Line 99M would occur within the existing 45m wide transmission line easement.
To enable the transition of the rebuilt line into the connection point at Yass 330kV substation, Transgrid may require an additional easement (approximately 0.5 ha) external to Yass 330kV substation. This would be confirmed during detailed design.

11. Will livestock still be able to graze under the new line?

Yes, livestock will still be able the graze on the easement. The width of the easement will be the same as before the line upgrade.

12. What about operating machinery in the easement? Where can I find out more about the activities which can be undertaken on or near easements?

To protect your safety and the network we have easement guidelines which restrict what activities you can undertake on an easement, like the height of a harvester you can use, the height of trees, types of fences you can build, and what items can be stored within the easement and in the vicinity of transmission lines.

For more information, please access our Easement Guidelines.

13. Where will the new structures go?

The new structures will generally be placed in the same position as the existing poles.

14. Who is the determining authority for the project?

Transgrid is the proponent and determining authority for the rebuild of TL99M and associated works at Yass substation.

15. What are the project benefits?

The project would result in the positive impact by facilitating the connection 290 MW of renewable energy into the National Electricity Market (NEM), which would further help to secure the long-term supply of electricity throughout the NEM.

Furthermore, positive economic benefits would be derived from the workforce sourcing daily needs and accommodation from the local area.

16. When will the project be built?

The upgrade of TL99M and associated substation works is expected to commence in mid-2024. The start date is subject to several variables change including funding from the operator of the CWF, who is funding the upgrade and substation works.

17. I am worried about environmental damage. How will the environment be considered and protected during the process?

On each transmission project, we ensure our activities and services minimise environmental impacts or reduce them as much as possible.
We do this to protect communities, to achieve sustainable growth and to comply with legislation.
Protecting the habitats of native species is a key priority.

Transgrid’s controlled environmental measures include:

  • avoiding clearing vegetation and mature trees
  • retaining vegetation while keeping foliage clear of powerlines
  • avoiding habitat disturbance
  • revegetation with local plants
  • providing escape routes for fauna.

18. As a landowner, will I be compensated for financial loss from disturbances to agricultural land from the project if it impacts my farm operations?

To access the transmission line easement, construction vehicles would use the existing access roads and access routes. Additionally, some new tracks would need to be constructed. Disturbances to farm operations including stock movements would aim to be minimised through consultation with landholders on an individual basis.

Transgrid is committed to undertaking any repair works of any tracks and watercourses which has been damaged during construction in consultation with the landholder.

Additionally, remediation of disturbed areas at the transmission tower and brake and winch sites would be carried out in consultation with the landholder.

Where direct disturbance and/or crop damage has occurred as part of the construction works (e.g., crop damage/ temporary loss of agricultural land from a construction bench), Transgrid would offer compensation to the landholder for that loss. Compensation payment would be determined on a case-by-case basis in consultation with the landholder.

Please contact the site manager or contact us on 1800 222 537 or email community@transgrid.com.au if you think there have been damage to your property which need to be rectified.

19. I am concerned about bio-security risks and pests and diseases with plant, equipment and people coming onto my land during the project. How is this managed?

Transgrid is committed to ensuring the risk of weed and pathogen infestation into agricultural areas is minimised as far as practicable.

Transgrid will consult directly with landholders prior to the commencement of construction to understand any specific biosecurity risks/issues on the subject land and incorporate any specific mitigation measures into the Construction Environmental Management Plan.

Accessing property has the potential to spread pests, diseases, weeds and contaminants.

Minimising biosecurity risks is a shared responsibility between Transgrid, our delivery partners, local and state government bodies, industries, landholders and the community.

We work closely with all of these parties to identify the best ways to reduce these risks, like using wash down bays to reduce the chance of our vehicles taking biosecurity risk from one property to another.

Please contact us on 1800 222 537 or email community@transgrid.com.au and we will confirm/ record your bio-security requirements in our access database.

20. I am worried about damage to indigenous cultural heritage. How will indigenous heritage be protected?

An Aboriginal cultural heritage assessment was carried as part of the environmental impact assessment of the project.

The assessment identified three Aboriginal heritage sites (stone artefact sites) within the project area that require management.

Of the three sites, impacts to two of the sites can be avoided through the implementation of appropriate mitigation during construction. Impacts to one site (Yass River Open Site 1) consisting of a stone artefact scatter and subsurface deposit could not be avoided.

As such, an Aboriginal Heritage Impact Permit (AHIP) was sought. Prior to carrying out works in the area subject to the AHIP, a salvage program would be implemented in accordance with the AHIP conditions.

Salvaged artefacts would be reburied on country under consultation with the Registered Aboriginal parties.

21. Is there any risk of power outages, as part of the project works?

Power outages are unlikely to occur during construction of the project. The network will be reconfigured to allow works to proceed and power to be maintained.

22. I am worried about a potential increase in Electric and Magnetic Fields as a result of a change in the transmission line.

Our EMF fact sheet provides general information on electric and magnetic fields in relation to our network as well as resources for further information. Go to: www.transgrid.com.au/media/1nrfxwtf/emf-fact-sheet.pdf 

The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has advised: “The scientific evidence does not establish that exposure to the electric and magnetic fields found around the home, the office or near powerlines causes health effects.”

23. Who can I contact to attain further information?

Please contact us on 1800 222 537 or email community@transgrid.com.au if you have any further questions or concerns about the rebuild of Transmission Line 99M or works at Yass Substation as part of the project.


Main REF


PDF 5.50 MB


PDF 9.55 MB


PDF 5.39 MB


PDF 9.88 MB


PDF 6.07 MB


PDF 4.01 MB


PDF 217.68 KB

Addendum REF


PDF 4.09 MB


PDF 507.19 KB


PDF 173.64 KB

Addendum REF 2


PDF 9.69 MB


PDF 169.30 KB


PDF 3.82 MB

Contact us

You can contact our Community Engagement team on 1800 222 537 or via community@transgrid.com.au.