beauly-knocknagael-tomatin reinforcement - ssen · pdf file · 2016-08-18the...

Beauly-Knocknagael-Tomatin Reinforcement

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Who We Are Scottish and Southern Energy Power Distribution is part of the SSE plc group of companies. We own, maintain and invest in the electricity networks in the north of Scotland – the electricity transmission network (132kV and above) and the electricity distribution network (below 132kV). In Scotland, Scottish and Southern Energy Power Distribution is made up of two businesses:

Scottish Hydro Electric Transmission (SHE Transmission) owns and maintains the electricity transmission network across the north of Scotland, in some of the UK’s most challenging terrain; and Scottish Hydro Electric Power Distribution (SHEPD) operates the high and low voltage electricity network that distributes electricity to around 700,000 customers in north mainland Scotland and the Scottish islands.

Keeping the Lights On and Supporting Growth

SHE Transmission owns around 5,000km of electricity transmission infrastructure which spans about 70% of the land mass of Scotland. Electricity networks like this provide a physical link between electricity generators and electricity users. We have three main objectives over the next decade:

To keep the lights on for our customers across the north of Scotland; To invest for a greener future; and To minimise, as far as possible, our impact on the environment.

Our Approach

Throughout the life of our projects, we aim to work positively with local communities and keep people informed about what we are doing. This is particularly important when we are developing a proposal and want to understand what local people think about our plans. We endeavour to take the time to discuss proposals with local community councils, encourage engagement from the wider community and listen to the feedback we receive. We will do our best to answer any questions and address issues or concerns that are raised with us. If our project progresses into construction, we will continue working closely with the local community to ensure that our work has as little impact on the lives of those living and working in the area and as many long term positive effects as possible.


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Project Background

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. We have obligations to offer non-discriminatory terms for connection to the transmission system, both for new generation and for new sources of electricity demand. The area around Tomatin is currently served by a double circuit 132 kilovolt (kV) overhead line (OHL) which runs from the Beauly substation to the Boat of Garten substation. There is an additional 212MW of contracted generation to the south of Inverness around the Tomatin area, which will significantly exceed the capability of our existing 132kV OHL. There are further wind farms in the early stages of development, which if progressed could contribute up to a further 67.5MW of renewable generation. These would also require connection into our network between Beauly and Boat of Garten. This additional generation has triggered the need for reinforcement of our existing electricity transmission network in the area. The Beauly-Knocknagael-Tomatin OHL Reinforcement is the proposed solution to enable the additional wind farm generation to be connected into our network.

Helping to Secure a Renewable Future - Proposed Beauly-Knocknagael-Tomatin Reinforcement

Source: Scottish Natural Heritage - Data Download Available at: https://gateway.snh.gov.uk/natural-spaces/index.jsp

Windfarm Grid Connection Point

Moy Inverness Substation

Farr Farr Substation

Tom nan Clach Proposed Tomatin Substation

Kyllachy Proposed Tomatin Substation

Allt Duine Proposed Tomatin Substation

Dunmaglass Proposed Farigaig Substation

Corriegarth Proposed Farigaig Substation

Stronelairg Fort Augustus Substation


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Project Description

The aim of the project is to overcome the current capacity issue and enable renewable energy to connect to the transmission network. The proposed Beauly-Knocknagael-Tomatin Reinforcement comprises the following elements:

Beauly to Knocknagael – Upgrade approximately 18km of 132kV double circuit OHL between Beauly substation and Knocknagael substation with a new higher capacity 132kV conductor using the existing towers. Knocknagael to Tomatin - Construct approximately 20km of 275kV double circuit OHL between Knocknagael substation and the proposed Tomatin substation on a new alignment. Knocknagael to Farr – Dismantle the existing 132kV OHL between the Knocknagael substation and the Farr substation. Tomatin Substation – Construct a new outdoor 275/132kV Substation near Tomatin, adjacent to the existing 132kV double circuit OHL. Knocknagael Substation – Construct an extension to the existing 275kV busbar to facilitate connection to the proposed 275kV OHL to Tomatin.

Note: On completion of the above the existing 132kV OHL from the Farr Substation to the Boat of Garten Substation will remain in place to maintain connection to the Farr windfarm and supply electricity to Strathspey.

Project Overview Map

Proposed Project Timeline

2014 2015 2016 – 2018 2018

Complete substation site selection Consent Decision Anticipated Construction Remove Existing 132kV OHL from Knocknagael to Farr

Complete OHL consultation and select preferred OHL route

Contract Tendering and Procurement

Commence EIA (OHL) and EA (substation)

Submit Proposal of Application Notice (PAN)

PAN Public Exhibition

Production of the Environmental Statement (OHL) and Environmental Appraisal Report (Substation)

Submit T&C Planning and Section 37 Consent Applications


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The Proposal

The following proposal is in relation to a new double circuit 275 kV OHL between the existing Knocknagael Substation, located approximately 8 km to the south of Inverness city centre, and the proposed Tomatin Substation. As with the majority of high voltage OHL in the United Kingdom, the proposed 275 kV OHL would be constructed using self supporting lattice steel towers. The typical average height of a 132 kV tower on the existing 132 kV OHL is 26.3 m. A typical average height of a 275 kV tower on the proposed route would be 46 m up to a maximum of 60 m. The spacing between the proposed 275 kV towers would vary depending on topography, altitude and land usage. The height and distance between towers will be determined later in the design process; however an average span of 350 m is estimated. A photo of a typical 275 kV OHL is shown on the left in photograph 1 and the existing 132 kV OHL is shown in photograph 2 on the right.

Construction Process

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;

erect temporary scaffolds and protection to roads, railways and rivers;

erect conductors (wires);

dismantle and remove temporary scaffolds and protection; and

re-instate tower sites and remove temporary access tracks.

Photograph 1 - Proposed 275kV OHL tower

Photograph 2 - Existing 132kV OHL tower

Tower Construction

Foundations A tower compound would be established at each tower location, within which foundation installation and subsequent tower erection would take place. Each compound would be fenced for safety. There are three main types of tower foundation, which are:

Mass Gravity; Piled; and Rock Anchor.

Foundation types and designs for each tower would be confirmed following detailed geotechnical investigation at each tower position. The extent of ground works would vary according to the foundation design, however good practice construction methods would ensure environmental impacts are minimised. Photograph 3 shows a typical mass gravity foundation under construction. An excavation is made (sides supported by sheet piles), followed by the pouring of a reinforced concrete base.

Photograph 3 - Conventional Foundation construction

Tower Erection Tower steelwork is generally delivered to site either as individual steel members or as prefabricated panels, dependent on the method of erection for the tower. The preferred method of assembly and erection would use a crane, as shown in photograph 4.

Photograph 4 - Tower Assembly and Erection

Photograph 5 - 275kV Tower with rollers

Conductor Stringing Prior to stringing the conductors, temporary protection measures (normally netted scaffolds), would be erected if necessary for features such as roads, railways and existing transmission infrastructure is to be crossed. Conductor stringing is carried out by running a pilot line through rollers on the towers, and a winch is used to pull the conductor off drums onto the towers, as shown in photograph 5 and 6 respectively.

Photograph 6 - Winch ready for stringing


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Overhead Line Route Selection - Stage 1 We have undertaken a detailed assessment to identify potential OHL route options. The approach adopted in identifying and assessing possible corridors capable of accommodating the proposed new OHL was consistent with national guidance on the routing of steel lattice towers. The guidance recommends a hierarchical approach to routeing which first avoids major areas of highest amenity first, then avoids smaller areas of high amenity, and which then considers factors such as backdrop, woodland and orientation. Using this guidance four OHL corridors (as shown on the map below) were identified to a number of potential substation locations as identified on poster 7. Corridor A emerged as the most favoured route option due to having the least potential impact with the key environmental features and sensitivities considered in this study, as shown in table 1 below. They are listed in order of preference under each environmental aspect. Table 1 - Environmental Appraisal

Environmental Aspect Appraisal

Landscape and Visual Corridor A is preferred as it follows a broadly similar alignment to the existing 132kV OHL. It is preferred in terms of amenity to property in Strathdearn and Strathnairn. Corridor C is less favoured as it follows a new alignment parallel to the A9 and railway where intermittent views can be expected. Corridor B is less favoured as it would be considerably more visible than Corridor A or C as it takes a route over higher ground. Corridor D is the least favoured as it passes close to a Scenic Landscape Area.

Ecology and Ornithology Corridor A is preferred on the basis that it follows the existing 132kV OHL, and in regards to birds it is reasonable to assume some habituation to this structure. Corridor B is less favoured as it crosses moorland likely to support ecologically valuable habitat and species. Corridor C is less favoured as it contains the greatest area of woodland and is likely to support larger number of birds and mammals. Corridor D is the least favoured as it passes through a Special Area of Conservation (SAC), and crosses a large area of moorland as per corridor B.

Cultural Heritage Corridor B is preferred as it contains the least cultural heritage features. Corridor C is similar to Corridor B, but may affect unscheduled sections of General Wades road. Corridor A is less favoured as it contains several scheduled monuments, however the route alignment would be unlikely to compromise their setting. Corridor D is the least favoured as it has the greatest potential to affect areas of known cultural heritage features

Geology, Hydrology and Hydrogeology

Corridor A is preferred as it crosses the least number of watercourses and avoids national designations. Corridor D is less favoured as it crosses the River Findhorn three times. Corridor B is less favoured as it is crosses the greatest number of watercourses. Corridor C is the least favoured as it has potential to affect the Littlemill SSSI.

Recreation Corridor A is preferred as it affects the least public recreation features, such as core paths and national cycle network routes.

Settlements Corridor A is preferred as it affects the least amount of settlements and avoids Tomatin. All other corridors are in close proximity to Tomatin.


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Overhead Line Route Selection - Stage 2 Further engineering and environmental assessment identified a potential OHL route alignment within Corridor A. A Limit of Deviation (LOD) has been identified along the proposed alignment, which varies in width according to identified constraints. The LOD has been developed to allow for micrositing of towers following further engineering design. The proposed 275kV OHL route alignment is presented below. We produced a consultation document on the proposal, which was published in December 2013. The proposed OHL route alignment and LOD is indicative at this time and is subject to completion of this consultation process to identify the final alignment that will be taken forward for consent. This exhibition is your opportunity to have your say on the OHL route alignment. We will continue to work with environmental consultants and overhead line engineers to identify a technically feasible and economically viable transmission OHL route which gives rise to:

The least disruption to the amenity of people living and working in the area; The least impact on the physical and natural environment, and on nationally important species, habitats and cultural assets; The least disruption to current land use and management practices; and The least disruption to existing and proposed infrastructure.

To allow work to be carried out safely, a clearance of 70m needs to be maintained between the new and existing overhead lines wherever they run in parallel.


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Tomatin Substation Site Selection

To locate a substation site we undertook a preliminary assessment using a map based search using information obtained from the statutory authorities and other recognised information sources. Seven potential options for the proposed substation were identified, which are presented opposite. Following criteria detailed within the our Site Selection Guidelines, an internal workshop and several site visits were undertaken to assess positive and negative aspects of each site location. This process eliminated the following sites on the grounds of cost, engineering, or environmental considerations:

Site 1 is the favoured location for the proposed substation due to the shorter length of new 275kV line, and the distance from sensitive tourism and recreational receptors.

Substation Option

Reason for Elimination

Knocknagael Too far from windfarm connections

Farr Not enough space due to topography

Boat of Garten Too far from windfarm connections, greatest length of new 275kV OHL and within the Cairngorms National Park

Site 2 Within Cairngorms National Park and in proximity to other Environmental Designations. New bridge over railway also required

Site 3 Within Cairngorms National Park and in proximity to other Environmental Designations

Site 4 Proximity to the Cairngorms National Park, highly visible to the A9 and railway, and poor ground conditions

An indicative layout of the Proposed Tomatin 275/132kV Substation at Site 1 is presented below.


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Knocknagael Substation Extension

As an integral part of this project there is a requirement to extend the existing Knocknagael 275/132kV substation. An indicative layout of the proposed substation extension is presented in red below.

Indicative layout of the proposed Knocknagael Substation Extension Photograph showing the existing layout of the Knocknagael Substation

Beauly to Tomatin 132kV OHL Upgrade

In addition there is a requirement to upgrade approximately 18km of the existing 132kV double circuit OHL between Beauly substation and Knocknagael substation with a new higher capacity 132kV conductor using the existing towers. This work will involve the detailed inspection of the towers and their foundations. Following the outcome of this inspection there may be a requirement to undertake upgrade works to the towers. A map showing the route of this element of the works is presented opposite.


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Questions for Consideration

We are seeking feedback at this stage before we select a site for the proposed new substation and a route for the overhead line. A Consultation Document on the proposed 275kV OHL route alignment and design was published in December 2013. An electronic copy of this can be found on line at www.sse.com/beaulyknocknagaeltomatin/ Printed copies of the consultation document will also be placed at: Consultees are invited to consider the follow:

Is the rationale for the project clearly set out in the consultation? Is the approach to the selection of the preferred OHL connection option, identifying the optimum balance of technical feasibility, economic viability and least environmental disturbance, clearly set out? Are there any factors you consider may have been overlooked or given either insufficient or too much consideration during the selection process? Do you have any other comments about the preferred OHL route?

How do I have my say?

Inverarnie Stores Farr Community Hall

Tomatin Village Store Strathdearn Hall

Dores Post Office Dores Parish Hall

We are keen to receive feedback from the local community and other interested parties on our proposal. Please also take the time at the event to speak to members of our project team, who are here to answer any questions you may have and explain the information presented on the boards. Comments can be submitted as follows:

At the exhibition today – complete a Comments Form and place it in the box provided. By post – complete a Comments Form and post it to our Liaison Manager (details below). By email – complete a Comments Form and email it to our Liaison Manager (details below).

Comments forms and all the information from today’s event will also be available to download from the project website at www.sse.com/beaulyknocknagaeltomatin. Information can also be posted out to you by our Liaison Manager upon request. Please make your comments as specific as possible in order to help us consider them in relation to our proposal. The closing date for comments of this consultation is Friday 31st January 2014. Contact details for the Project Liaison Manager are as follows: Lisa Marchi

SHE Transmission

10 Henderson Road, Inverness, IV1 1SN

Email: [email protected]

Mobile: 07825 015507

Proposed Tomatin 275/132kV Substation Site option 1 - Photo taken facing west towards Garbole from the existing forest access road.

beauly-knocknagael-tomatin reinforcement - ssen · pdf file · 2016-08-18the...

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