Maragle Switching Station and Transmission Line

The Project

UGL submitted a competitive tender to TransGrid under the existing Panel Agreement for a high voltage separable portion transmission and switching station project based in Maragle in New South Wales, approx. 500km /southwest of Sydney, as part of the Snowy Mountain 2.0 Project.

TransGrid awarded to UGL Engineering Pty Ltd contract SR1610931 (1611) for the Maragle Switching Station and Transmission Line on 21 October 2020, here in identified as the ‘Main Contract’.

The Contract is based on the General Conditions of Contract established under the Panel Agreement with amendments to suit the specific conditions and risks of the project as well as incorporating a provision to manage COVID-19.

The scope of the work under the Contract is for the design, supply (except for Principal supplied materials), construct manage, test and commissioning of a new 330kV switching station, OPGW/OHEW upgrade cut into existing Line 64, and 10km of two new double circuit 330kV transmission lines.

Project Overview – 330kV Switching Station

The scope of works includes the Design, Supply, Construct, Testing and Commissioning of a new 330kV Switching Station

1. Bulk earthworks suitable for construction and laydown areas for the Maragle switching station construction and a separate laydown area for the transmission line work;
2. Communication equipment within the Maragle substation and the remote substations (Upper Tumut and Lower Tumut Substations) to link the Snowy 2.0 Project and the Maragle Substation to the network.
3. Delivery to Site, erection and site acceptance testing (SAT) of the HV equipment supplied under Section 1.14;
4. Furnishing and cleaning (until the date of Practical Completion) of the new 330kV secondary systems building;
5. Secondary systems (including communications, protection, metering and control systems) in the new Maragle 330kV switching station;
6. Permanent access road linking Elliot Way to Maragle switching station. The access road spur to the future 500kV substation shall be constructed under a separate contract.
7. All testing and commissioning including but not limited to factory acceptance testing (FAT), SCADA acceptance testing, site acceptance testing (SAT) and commissioning of the new 330kV switching station;
8. All studies necessary to inform the design and construction of the Maragle substation including weather impacts and elevation of the Site;
9. Remote end protection, control, automation and communication Works of line 64 located at remote end substations (Upper Tumut and Lower Tumut Substations).

Project Overview – 330kV Transmission Line

1. New or upgrade of existing access tracks, including the need for water crossings, as required for the construction and maintenance of the new 330kV transmission lines, cut into Line 64 at Structure 43, and the installation of OPGW on Line 64;
2. Clearing and disposal to form the 120m wide easement required for the new 330kV transmission lines.  The easement must be cleared in accordance with the Transmission Connection EIS determination once received
3. Ancillary provisions, including brake and winch sites, crane pads, site compounds and equipment laydown areas;
4. Two double circuit 330kV transmission lines to connect the new Maragle switching station to the Snowy 2.0 cable yard in Lob’s Hole Ravine area. Design for all critical load cases, including snow and ice loading and vibration control. Prototype assembly and fabrication drawings are required for all tower types. Full scale load testing to destruction will be required for possibly (to be determined) two types;
5. Double circuit 330kV transmission line with OPGW connecting the new Maragle switching station cut into Line 64. Design of the new double circuit line for all critical load cases, including snow and ice loading;
6. New OPGW and  earthwire on Line 64 between structures 21 and 69, approximately 19km. The work includes any tower earth peak and body strengthening required;
7. Disposal of all redundant transmission line items;
8. All studies necessary to inform the design and construction of the transmission lines including weather impacts and elevation along the length of the transmission lines;