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Western Power Corporation (WPC) proposes to construct an Eastern Terminal electrical substation on a 20 hectare area of land in the Kalamunda, Mundaring or Gosnells area, together with the associated upgrading of the power transmission line from Collie to the proposed substation, and the progressive construction of additional transmission lines.  Western Power state:

Western Power is currently planning to complete this project in two stages.  Initially this will involve the construction of a 330,000 volt (330kV) switchyard, due to be completed by November 2010. Over time, Western Power proposes to further develop this site into a 330/132 kV terminal substation.

Western Power has engaged Environmental Resources Management (ERM) to assist in completing a site selection process, analysing all environmental, social, technical and economic constraints in the area. Key stakeholders, including the community will be invited to provide input into the constraints analysis, to assist in determining the most suitable site.

The study area under investigation includes land within the Shire of Kalamunda, the Shire of Mundaring and the City of Gosnells.

The eastern metropolitan hills area was selected because of the proximity of existing 132,000 volt (132 kV) and 330,000 volt (330 kV) transmission lines from the Kwinana and Collie power stations that are needed to connect with the substation, minimising the impact on the local environment.  

The Study Area

Western Power identified a wide area which they deem appropriate for the sub-station to be established.  Localities within the study area include Carmel, Bickley Valley, Hackett's Gully, Paulls Valley, Pickering Brook and Piesse Brook.

Click on this link to view the constraints map of the “study area” which is marked with a red dashed line within which the proposed substation would be located.

http://www.wpcorp.com.au/documents/currentProjects/easternTerminal/All%20Constraints.pdf

The study area encompasses substantial areas of State Forest and National Park and is a highly valued tourist precinct and recreational area.  Almost all of the study area is a Priority 1 or Priority 2 water catchment area.

The Project

Western Power’s preferred option to reinforce its bulk transmission network is to establish a new 330kV transmission line from Shotts Terminal (near Collie) to Wells Terminal (near Boddington Gold Mine) and a double circuited 330kV transmission line from Wells Terminal to Eastern Terminal.

This would involve upgrading the existing 132kV transmission line shown on the constraints map.  Eastern Terminal will need to be cut into two existing 330kV transmission lines – Kwinana (KW) to Northern Terminal (NT).  The second side of the Shotts Terminal will be strung to Wells Terminal 330 kV double circuit transmission line (eg. See the below map).  The new 330 kV transmission line would allow the connection of new generation sources remote from the Perth metropolitan area.

The substation would be constructed in two stages.  In the first stage a 330kV switchyard would be constructed on 4 hectares, and connected to the three existing transmission lines (see map).  The second stage would involve the progressive development of two terminal substations within the same area: a 330/132 kV terminal substation covering 20 hectares, incorporating a separate 132 kV switchyard, transformers containing up to 300,000 litres of transformer oil, and associated 330kV and 132kV transmission lines.

The substation would have the capability of connecting to a total of 27 transmission lines.  In addition to the terminal substation, the ultimate configuration of the project would potentially include up to 13 x 330 kV transmission lines on 50 m high steel lattice towers, and up to 14 x 132 kV transmission lines on 25 m high towers.   There would be up to 14 x 60m + wide cleared corridors for the transmission lines (2 lines per corridor), consuming at leaste 6 hectares of forest per km of corridor.

What happens in a terminal substation?

A terminal substation fulfils two primary roles:

• It provides a connection point where transmission lines of the same voltage may be interconnected.  This enables an electricity supply to be provided to a new demand centre, or a greater degree of power supply security within the existing system to be achieved.
• It is a transformation point where transmission voltages are lowered or stabilised to make them suitable to supply zone substations in the metropolitan and country transmission system.

For effective operation of the power system, terminal substations and zone substations are best installed close to or within areas where the demand for electricity is greatest.

What will the terminal substation look like?

Terminal substations vary in appearance, but consist of many high voltage transmission lines, lower voltage power lines and equipment.  They emit loud constant humming noises and are lit all night.  They incorporate several transformers that hold around 100,000 litres of mineral oil each, buildings housing specialised equipment, control facilities and typically two switchyards (330kV & 132kV). The Eastern Terminal substation would be surrounded by a security fence, would have an access road, and would be surrounded by a low vegetation fire “buffer” zone.

Why Here?

The Eastern Terminal substation would be linked to 3 existing lines that run through the area.  On the study area map provided by Western Power, referred to earlier, Eastern Terminal substation would link to the dark blue line (330kV) and the orange line (132kV to be upgraded to 330kV).  It is expected that the existing 66kV line would in time be upgraded to 132kV and also linked into the terminal substation.  Ideally the substation would be built close to these lines.  However, as you can see on the map, these lines intercept in the Hackett’s Gully area which would be Western Power’s preferred site.

Western Power’s decision to build the terminal substation in the study area is based only on technical and economic factors.

Community consultation?

Western Power state that they wish to engage the community and key stakeholders in the site selection process.  We believe Western Power’s consultation processes to be a sham.  Western Power has not consulted the community in any way about the proposal to locate a 20 hectare terminal substation in this precious area.

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