Two 11,000-volt submarine cables currently supply Scotland Island and the West Pittwater residents and businesses. Ausgrid is implementing measures to improve energy security to the area following extended power outages in December 2013 and February 2015.
The installation of a backup electricity cable to Scotland Island is in the final stages of design with construction having started in February 2020. This work should take up to five months to complete.
The new cable will be housed in a conduit (plastic pipe) installed using a horizontal directional drill (HDD) to bore under the waterway between Church Point Carpark and Richard Road, Scotland Island.
A switching system will also be installed so we can isolate faults in the overhead network, as required. This will mean we can restrict power outages to a smaller number of residents whilst the problem is being resolved. In addition, space will be provided for future electricity cables and fibre, which can be used for future services.
In the event of an overhead outage, the existing submarine cable will supply power to the western side of the Island, and the new cable will supply the eastern side. This will allow for a much quicker restoration of power to the half of the island which does not have an issue on its overhead network.
Since the major outage in 2015, there have been six smaller outages on Scotland Island and West Pittwater. These have been associated with storm events or vegetation coming into contact with the overhead network. Access and safety issues to both locations have been challenging during these outages, and in turn have contributed to the time taken to restore power.
Ausgrid has completed feasibility and design studies to determine the best solution for each community. We have assessed several options and are moving forward with solutions that aim to minimise the impact of electrical outages to the residents and businesses of Scotland Island and West Pittwater.
Ausgrid has concluded that two different approaches are required for Scotland Island and West Pittwater due to the layout and design of the existing electricity network in each of these areas;
Scotland Island’s arrangement - a circular network
West Pittwater’s arrangement - a linear network
A number of project scenarios were assessed for each location including the original cable loop to arrive at the currently proposed solutions.
Current solution for Scotland Island
Ausgrid’s solution uses Horizontal Directional Drilling (HDD) to underbore beneath the ocean bed from Church Point to Richard Road, Scotland Island to install a new electricity cable. Both the new and existing cable will be in service at the same time to minimise the impact of a failure to a single cable. The new cable will lie in a conduit (plastic pipe) below the ocean bed rather than on the ocean floor as the current cable does, which minimises the risk of environmental impact or cable damage.
As part of the design for the HDD bore, Ausgrid is considering future energy requirements for the Island.
A geotechnical study was completed late 2018 at Church Point, Carols Wharf and along the marine cable route.
Under the Environmental Planning and Assessment Act 1979, Ausgrid is the determining authority for this project.
An environmental assessment will be prepared on the works in accordance with Part 5 of the Environmental Planning and Assessment Act 1979 and Clause 228 of the Environmental Planning and Assessment Regulation 2000.
Community feedback has been sought at various stages since 2017, to assist the project team better understand the needs of the Scotland Island community. This feedback has been integral in our decision-making.
Ausgrid has met with key stakeholders including Northern Beaches Council, Rural Fire Service, National Parks and Wildlife, local Members of Parliament (State and Federal) and community group representatives to get their input and provide project updates.
Ausgrid welcomes questions or comments about the project at any time. Please contact us on 1800 604 765 or email firstname.lastname@example.org