Connecting Archer Zone Substation to Palmerston Zone Substation
Power and Water is in the final stages of construction of a 66kV transmission line connecting Archer Zone Substation to Palmerston Zone Substation. The new transmission line will increase the capacity, security and flexibility of the electricity transmission and distribution networks servicing the growing Palmerston and rural areas.
About the project
What route will the transmission line take to connect Archer Zone Substation to Palmerston Zone Substation?
The transmission line route partly follows the previous 132kV and 66kV transmission lines. Starting at Archer Zone Substation it will run through Crown land and the Marlow Lagoon utility easements to the edge of Durack, on land currently being developed by CIC Australia. It will then follow the road reserve along and across Roystonea Avenue at Yarrawonga and turn before Temple Terrace ending at the Palmerston Zone Substation. See the route map for details.
Why has this transmission line route been chosen?
This route has been chosen to:
- maximise the benefit to customers by:
- providing a network that is more resilient to extreme weather and electrical storms
- improving supply reliability through alternative and more diverse routes.
- minimise the cost impact to customers because
- a portion of the infrastructure needed is already in place.
How will the transmission line be installed?
Installation of the transmission line will be a combination of approximately:
- two thirds overhead, using existing power poles that require no upgrades and replacing/upgrading some existing transmission towers to mono pole structures
- one third underground, using existing infrastructure and installing new infrastructure.
Which parts of the line will be overhead and which will be underground?
From Archer Zone Substation the transmission line will run overhead through Crown land on existing power poles already in use.
Through the Marlow Lagoon utility easements, one line of existing transmission lattice towers will be replaced/upgraded with new slim profile transmission poles able to accommodate the existing 132kV line and the new 66kV line.
It will then carry on through Crown land, again using existing power poles until it reaches the edge of Durack on land currently being developed by CIC Australia. From this point the line will be undergrounded at the edge of the development in pre-existing conduits, and then follow the road reserve along and under Roystonea Avenue at Yarrawonga and turn before Temple Terrace ending at the Palmerston Zone Substation.
Who will undertake these works?
Power and Water has contracted MG Electrical, a local Darwin business, to construct the new and remove the old transmission line towers. MG Electrical will undertake both the overhead and underground sections of the works.
(added 26 May 2017)
When will construction start?
Construction commenced in October 2017and will take place in three stages, primarily in and around the exiting tower locations:
- Stage one: 9 October to 30 November 2017 - concrete footings constructed for the new poles.
- Stage two: will commence in June 2018
- New poles to be transported to site and assembled (cross arms attached).
- Poles to be stood and new powerlines strung.
- Towers being replaced to have tops and arms removed.
- Stage three: to follow from Stage two - remove remaining tower structures, old footings and construction site cleaned up.
Underground installation has now been completed.
(updated 21 May 2018)
What installation options were considered for Marlow Lagoon properties?
Power and Water considered a number of solutions for the Marlow Lagoon section to accommodate the new transmission line including:
- installation of a new row of poles
- undergrounding of the new line
- upgrading one row of existing towers (on the western side of the easement) to accommodate the new line.
Why can’t the existing transmission towers in the Marlow Lagoon utility easement be used?
The existing towers were designed for the current load and adding more conductors would compromise their strength. Replacing the row of towers on the western side of the easement that currently only accommodates a single 132kV line (three conductors) with stronger slimmer poles will allow the new 66kV line to also be accommodated without increasing the number of poles/towers in the easement. Poles will also take less ground space with the base area needed for a pole being approximately two meters in diameter compared to a tower footprint of approximately 8m x 8m. See the drawings of the existing transmission and proposed transmission arrangements.
Will footings from the replaced towers be removed?
Footings from the towers being replaced will be removed up to approximately 500 mm below the surface.
Why can’t the transmission line be put underground through the Marlow Lagoon utility easement?
The Marlow Lagoon easement is a dedicated utility corridor already in existence and in use. Replacing/upgrading poles through the utility easement, without increasing the number of poles will cause less disruption to property owners/occupiers and is a quicker installation process than undergrounding.
Undergrounding would require a corridor of 8 – 10 metres to be cleared of all trees, shrubs and any plantings. This would allow the necessary machinery to have safe manoeuvrability for trenching, conduit laying and cables to be pulled through. Trenching would also create disruptions in the form of dust and noise.
The new mono poles have a smaller base footprint than the existing towers that will also make more ground space available to property owners/occupiers.
To be able to restore power to customers as quickly as possible Power and Water prefer to install transmission lines above ground wherever feasible. Overhead lines allow for quicker fault-finding and repair, easier access and general maintenance.
The transmission line will be installed underground for a portion of the route to meet Department of Infrastructure, Planning and Logistics’ future major traffic corridor requirements.
Cost is also a factor. Traditionally overhead construction costs are around $300,000 per kilometre, the underground equivalent would cost around three times more.
Where will the new poles be placed e.g. next to existing, in same line as existing?
It is anticipated the new mono pole structures will be placed in near alignment to the existing 132kV towers with the distance between the new pole and existing tower being within five meters. This will be confirmed once design is finalised.
Will any additional poles be installed?
It is anticipated that no additional poles will be installed. One existing row of towers only will be replaced through the Marlow Lagoon property easements, one pole for one tower.
How many transmission towers will be replaced?
In total eight towers are identified for replacement, made up of six towers on properties within the easement and one tower at each end of the properties.
Will any of the new poles be installed in properties that do not currently have transmission towers in them?
No. All new mono poles will be installed in the same properties as the current transmission towers, in near alignment with the existing 132kV circuit and within close proximity to the towers to be removed (exact distance to be confirmed once tender is awarded).
How far from the edge of the existing easement will the nearest conductor be?
The horizontal distance is approximately seven metres from the easement edge to the nearest conductor. The minimum clearance required from any building to the nearest conductor is 6.7 metres, as per Australian Standards.
Will steel or concrete poles be used when replacing the row of towers?
The row of towers being removed will be replaced with steel poles.
(updated 26 May 2017)
When will the second row of transmission towers that currently accommodates a 132kV and a 66kV line through the Marlow Lagoon property easements be replaced/upgraded to the slim profile poles?
Power and Water has no plans to replace/upgrade the second row of lattice towers at this time.
Will Marlow Lagoon property owners be notified if access to property is required?
Power and Water or the contactor installing the new line and mono poles will contact property owners before entering and commencing work on properties.
How long is the Marlow Lagoon portion of the works expected to take?
Stage 2 construction works are proposed to be undertaken for three weeks from the 11th of June 2018 through till 1st July 2018, changing out approximately one tower to pole per day. Stage 3 tidy up works are expected to take approximately 2 weeks to complete.
(updated 21 May 2018)
Will existing trees be removed from the route of the new transmission line?
Some trees will be removed, but only where necessary to allow for the works to take place.
What types of activities are allowed within a utility easement?
See the types of activities that are allowed within an electricity easement.
What effect will adding the new 66kV line to this utility corridor have on the electromagnetic field in the area?
Power and Water commissioned Entura, to study and report on the electric and magnetic fields that may be generated from the installation of the new 66kV transmission line within the existing Marlow Lagoon utility easement. See the Executive Summary of the report. The full report is available and can be obtained by contacting the Project Manager via the Feedback Form or calling 1800 245 092.
The Australian Government’s Australian Radiation Protection and Nuclear Safety Agency also offers the following factsheets in relation to powerlines and health:
How much disruption is expected for residents in Durack to install the new 66kV transmission line?
It is anticipated minimal disruption will be caused to residents in the Durack area. As part of the Durack extension development a shared services easement is pre-existing and has spare underground electrical conduits available for use. Minimal trenching will be required in this area to change the cable from overhead to the underground and for approximately 15 metres either side of the service pits. Installing the cables will require access to the easement service pits by trucks carrying the cables and workers installing them.
What route will the works take from Durack to the Palmerston Zone Substation?
Installation of the new transmission line will take place in the easement on the Roystonea Avenue road verge, Durack, from Lot 12968 (behind 8 Teece Street) to Lot 7823 (Palmerston Bus Terminal). It will then cross Roystonea Avenue into Lot 1132 (36A Georgina Crescent, Yarrawonga) through a shared services easement into the Palmerston Zone Substation.
How long is the Roystonea Avenue portion of the works expected to take?
Roystonea works are complete with the exception of lawn re-establishment on Georgina Crescent which are underway.
(updated 21 May 2018)
Will there be any disruption to traffic along Roystonea Avenue while works take place?
As the majority of works will be taking place on the road verge, minimal disruption to road traffic is anticipated.
However, the footpath may be excavated past Bunnings.
For public safety barriers will be erected around the work site as it moves along the road and traffic management may be in place while directional drilling takes place at road crossings. Any disruption to road access will be advertised.
Will there be any disruption to businesses in the area?
Businesses backing onto Roystonea Avenue may experience some temporary noise and dust while works move along the road. All efforts will be made to keep any disruption to a minimum.
How can I give my feedback about this project?
For more information about this project or to give your feedback you can contact the Project Manager by:
- completing the Feedback Form
- phone on 1800 245 092.
This page will be updated as more information becomes available.
Last updated: 26 May 2017