Proposed Gills Bay 132kV Project Background Scottish Hydro Electric Transmission plc (SHE Transmission) is the transmission licence holder in the north of Scotland and has a duty under Section 9 of the Electricity Act 1989 to facilitate competition in the generation and supply of electricity. The company also has obligations to offer non-discriminatory terms for connection to the transmission system, both for new generation and for new sources of electricity demand. In March 2010, the Crown Estate announced the successful companies that will develop marine generation in the Round 1 lease areas in the Pentland Firth and Orkney Waters. This includes a generation potential of up to 1600 MW (wave & tidal). Two tidal developers in the vicinity of Gills Bay KDYH DFFHSWHG 6+( 7UDQVPLVVLRQ¶V connection offers, phased between 2016 and 2018/19. System studies have established that this anticipated capacity exceeds that available via the existing network in the north of Scotland. There is also currently no transmission infrastructure in the Gills Bay area where some of the marine generation is to be located. As a result, SHE Transmission is proposing to construct a new 22km double circuit 132 kilovolt (kV) (1 kV = 1000 volts) overhead line (OHL) supported on lattice steel towers between a proposed new substation south of Thurso (Thurso South) and a new substation proposed at Philips Mains, south of Gills Bay (Gills Bay substation). Helping to Secure a Renewable Future ² Proposed Gills Bay 132kV Source: SSE Power Distribution RIIO-T1 Price Control Period 1 April 2013 to 31 March 2021 - Supporting Document 5 Source: The Crown Estate - Pentland Firth and Orkney Waters Strategic Area Review Project, July 2013 Consultation Process As well as endeavouring to select the best possible connection option (route and conductor support type combination), we want to keep everyone affected by the proposal informed of our intentions. We firmly believe that early and regular communication and consultation Have Your Say with those likely to be affected by the proposal forms a critical part of its development. This exhibition is your opportunity to comment on and ask questions In order to address the need for the proposals a series of studies to determine technical about our proposals so far. We would greatly appreciate it if you would feasibility, economic viability, land use and any environmental constraints have been take the time to fill out our short questionnaire and post it in the undertaken. This included corridor studies to examine options for the reinforcement of comments box. transmission infrastructure in Caithness, site selection studies to identify a proposed substation location at Philips Mains, and a routing study which evaluated alternative route Alternatively, you can contact our Liaison Manager: alignments and conductor support type combinations. Gavin Steel As part of these studies we consulted with the Highland Council, statutory and Scottish Hydro Electric Transmission plc non-statutory bodies and other interested parties to obtain information and feedback. We 10 Henderson Road also undertook a public exhibition in June 2011 regarding the Gills Bay substation site Inverness selection. Following this event a proposed site at Phillips Mains was chosen as the IV1 1SN preferred site. The Gills Bay substation will be the subject of a separate application for E: [email protected] planning permission in 2014 and a further public exhibition will be held at this time. T: 07584 313481 A Consultation Document on the proposed 132kV OHL route alignment and design has Please submit your comments on the OHL proposal at the end of the been published. A copy of this can be found on line at www.sse.com/Gills Bay. Copies event today or by 9th September 2013. If you require longer to respond have also been placed at The Highland Council Service Point in Thurso, Caithness please let us know and we will endeavour to accommodate this. Horizons in Thurso, and The Highland Council Planning & Building Standards office in Wick. 1 Gills Bay 132kV Project Description The aim of the project is to provide electricity transmission infrastructure in the Gills Bay area where marine generation is to be located. The main elements of the project are as follows: Construction of a new double circuit 132 kV OHL (lattice steel tower) from the proposed Air Insulated Switchgear (AIS) Thurso South substation (currently being progressed via a different project) to the proposed Gills Bay Gas Insulated Switchgear (GIS) substation (c. 22km). Construction of a 132 kV / 33 kV GIS substation located at Phillips Mains Farm in the vicinity of Gills Bay. Connection of the new 132 kV OHL to the proposed AIS substation at Thurso South and the GIS substation at Phillips Mains Farm. Project Program Landscape in the vicinity of the Hill of Olrig The current programme for the Gills Bay Substation is shown below: Develop and compare substation sites options Complete Identify preferred substation sites Complete Undertake public exhibition for preferred substation sites Complete Submit Proposal of Application Notice (PAN) for substation site Early 2014 PAN Exhibition for Substation Town & Country Planning Application Early 2014 Complete Environmental Appraisal Summer 2014 Apply for Town and Country Planning consent Summer 2014 Start Construction Summer 2015 Phased completion and commissioning 2017 The current programme for the Gills Bay 132 kV Overhead Line is shown below: Develop and compare OHL route options Complete Identify preferred route for overhead lines Complete Publish consultation document on overhead lines Complete Undertake public exhibition for overhead line consultation Sept 2013 Refine the preferred route and select a proposed route Sept 2013 Complete Environmental Impact Assessment Summer 2014 Apply for Section 37 consent Summer 2014 Start Construction Summer 2015 Phased completion and commissioning 2017 Overhead Routing Study Process We have worked closely with a team of environmental consultants and overhead line engineers to identify a technically feasible, economically Project Overview Map viable, new transmission OHL which gives rise to: least disruption to the amenity of people living and working in the area; least impact on the physical and natural environment, and on nationally important species, habitats and cultural assets; least disruption to current land use and management practices; and least disruption to existing and proposed infrastructure. A number of route options were assessed (see opposite), taking into account the technical requirements to connect to the existing electricity network. A process of analysis and comparison of potential routes was then followed. The assessment has been based on: detailed baseline data on land use and environmental character and sensitivity, obtained from desk sources and site visits; identification of potential effects, to inform strategies for enhancing positive outcomes and for avoiding, reducing, controlling or offsetting potentially undesirable or significant negative outcomes; initial consultations with key stakeholders to inform the above and the subsequent refinement of the routing study and selection of the preferred route. The preferred overhead line alignment is route option 1A, which is shown in greater detail on Poster 5. The final proposed route will be determined after this detailed consultation and will be subject to an environmental impact assessment. The preferred route is considered to represent the optimum balance of technical, economic and environmental feasibility. The precise route alignment of the OHL and the location of individual towers will be determined following completion of ongoing detailed surveys to identify engineering, land use or environmental constraints which may require localised modifications to the route. 2 Gills Bay 132kV The Preferred Overhead Line Tower Design Three conductor support types were considered initially: 1. Lattice steel towers; 2. Twin Trident woodpole (Comprising two 132 kV OHL circuits supported on Trident woodpole supports, running in parallel along a single route alignment); or 3. Dual Trident woodpole (Comprising two 132 kV HL circuits support on Trident woodpole supports following different alignments between the two substations): Initial engineering and business case studies concluded that the dual Trident configuration did not present a feasible alternative. This configuration was therefore not considered further. Following environmental analysis, route Option 1A was identified as the most appropriate route option for either lattice or twin trident. A subsequent comparison was then completed of whether the preferred route could better accommodate lattice steel towers or twin Trident woodpoles. This analysis concluded that on balance of the considerations that lattice steel towers were the preferred option. The following table details indicative key design paramaters of each type of tower. Indicative Key Design Parameters Overhead Line Tower Options Single 132kV trident woodpole The above L7 132kV OHL lattice steel tower is indicative of the tower type proposed for the preferred route option. Construction High voltage OHL construction typically follows a standard sequence of events which are: complete pre-construction surveys, as required by a construction environmental management plan; establish access (including any necessary vegetation management); install tower foundations; assemble and erect towers; Indicative design of a single 132kV trident woodpole.
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