consultation document - ssen transmission€¦ · a new 4 km double circuit 132 kv ohl supported by...

28th May 2012

Caithness Reinforcements Dounreay – Mybster 275 kV/ 132 kV

Consultation Document

Scottish Hydro Electric Transmission Limited (SHETL)

Caithness Reinforcements Dounreay – Mybster 275 kV/ 132 kV

Consultation Document

Published by Scottish Hydro Electric Transmission Limited

10 Henderson Road Inverness IV1 1SN

28 May 2012

CONTENTS

1 INTRODUCTION 1

1.1 ABOUT THE CONSULTATION DOCUMENT 1

1.2 THE NEXT STAGES 2 1.3 STATUTORY CONSENTS PROCEDURE 3

2 THE PROPOSALS 4

2.1 THE NEED FOR THE PROPOSAL 4

2.2 PROPOSAL OVERVIEW 6 2.3 LINE DESIGN AND CONSTRUCTION 6

3 ROUTE SELECTION METHODOLOGY 10

3.1 OVERVIEW 10

3.2 IDENTIFICATION OF ROUTEING CONSTRAINTS 11 3.3 ROUTEING STRATEGY: DEVELOPMENT OF ROUTE CORRIDORS 12

3.4 DEVELOPMENT OF ROUTE OPTIONS 13

4 ENVIRONMENTAL CHARACTER 14

4.1 INTRODUCTION 14 4.2 LANDSCAPE (INCLUDING TOPOGRAPHY, LANDFORM AND SETTLEMENT PATTERNS) 14

4.3 ECOLOGY AND ORNITHOLOGY 15

4.4 CULTURAL HERITAGE 15

4.5 GEOLOGY, HYDROGEOLOGY, AND HYDROLOGY 16 4.6 SOILS, LAND USE AND AGRICULTURE 17

4.7 FORESTRY AND WOODLAND 17

4.8 TRANSPORTATION AND INFRASTRUCTURE 17

4.9 SOCIO-ECONOMICS, RECREATION AND TOURISM 18 4.10 PROPOSED NEW DEVELOPMENT 18

5 CONSULTATION ON THE PREFERRED ROUTE 19

5.1 ROUTE SELECTION PROCESS 19

5.2 THE PREFERRED ROUTE 19 5.3 QUESTIONS FOR CONSIDERATION BY CONSULTEES 20

ANNEX A FIGURE 1: PREFERRED ROUTE OVERVIEW (1:250K @ A3) FIGURE 2 A, B AND C: PREFERRED ROUTE (1:50K @ A3) FIGURE 3: INDICATIVE TOWER DESIGNS FIGURE 4A, B AND C: ROUTE OPTIONS FIGURE 5A, B AND C: ENVIRONMENTAL CONSTRAINTS (1:50K @A3)

Scottish Hydro-Electric Transmission Limited (SHETL) Dounreay - Mybster 275 / 132kV

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Caithness Reinforcements - Consultation Document Dounreay - Mybster 275 kV / 132 kV

Comments on this document should be sent to:

Lisa Kelly

Scottish Hydro Electric Transmission Limited

10 Henderson Road

Inverness

IV1 1SN

e-mail address for representations: [email protected]

Copies of this document can be found online at: www.sse.com/DounreayMybster

Copies will be placed on deposit for public viewing during normal opening hours at the following locations:

Thurso Service Point Council Offices Rotterdam Street Thurso KW14 8AB

Caithness Planning and Building Standards Office Market Square Wick KW1 4AB

Thurso Library Davidson's Lane

Thurso Caithness

KW14 7AF

Caithness Mobile Library (Wick)

Please submit comments by: Monday 16th July 2012

Published by: Scottish Hydro Electric Transmission Limited (SHETL)

mailto:[email protected]�

http://www.sse.com/DounreayMybster�


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Glossary 275kV 275 kilo-volt capacity of an electricity power line

132 kV 132 kilo-volt capacity of an electricity power line

ancillary works works that facilitate the main development, such as access tracks, temporary construction compounds, etc.

EIA Environmental Impact Assessment

ES Environmental Statement

GWDTE Groundwater Dependent Terrestrial Ecosystem

Holford Rules A set of 7 rules, first developed in 1959 by Sir William Holford, which define the principles of route selection and which continue to inform transmission line routeing in the UK.

OHL overhead line

planning application an application for planning permission under the Town and Country Planning (Scotland) Act 1997, as amended by the Planning etc (Scotland) Act 2006;

preferred route the route alignment which is considered to represent the optimum balance between technical, economic and environmental considerations and which is consulted on herein;

proposed route the final route alignment which will be brought forward with an application for consent;

route alignment the route followed by a transmission line across the land;

route corridor a linear area of search within the study area, through which a new transmission line could be located;

route option one of several possible alignments which a new transmission line could follow, within identified route corridors

route selection process the process of selecting a preferred route alignment for a new transmission line;

Section 37 application An application for development consent under section 37 of the Electricity Act 1989

SAC Special Area of Conservation

SAM Scheduled Ancient Monument

SHETL Scottish Hydro Electric Transmission Limited

SPA Special Protection Area

SSSI Site of Special Scientific Interest

study area the area of land, at its widest extent, which was considered within the route selection process, defined here as the broad area between Dounreay to the west, Thurso to the east, the coast to the north and Mybster to the south


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Executive Summary This consultation document invites all interested parties to comment on the proposals by SHETL to construct a new 26 km double circuit 275 kV overhead line (OHL), supported by steel lattice towers, between a substation at Dounreay and a new substation at Spittal, via a new substation south of Thurso; and a new 4 km double circuit 132 kV overhead line, supported by steel lattice towers, between the new substation at Spittal and an extension to the existing Mybster substation. The proposed development forms part of a national strategic reinforcement of the electricity network in the north of Scotland.

This consultation document outlines the process by which the preferred route has been selected. Comments are now sought from a range of statutory authorities, key stakeholders, politicians and the general public.

The objective of the process by which the preferred route has been selected was to identify a technically feasible (both in terms of constructability and long term maintenance), economically viable transmission route, between defined points, which give rise to the:

• 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 and other economically beneficial uses of land.

A preferred route has been identified, which is considered to represent the optimum balance of technical, economic and environmental feasibility.

The proposed 275 kV OHL between Dounreay and Spittal and 132 kV OHL between Spittal and Mybster will be constructed using self-supporting steel lattice towers. The towers used for the 275 kV OHL and the 132 kV OHL will be similar in appearance (both being steel lattice structures); however the 275 kV towers will be of larger dimensions than those for the 132kV OHL.

An initial study area was defined for the consideration of environmental constraints, which covered the broad area between Dounreay to the west, Thurso to the east, the coast to the north and Mybster to the south. Identified environmental constraints in this area included: Sites of Special Scientific Interest (SSSIs); Special Areas of Conservation (SAC); listed buildings; scheduled monuments; areas of grade 3 agricultural land; registered private water supplies to individual dwellings; watercourses; the Thurso-Wick railway line; various major and minor roads; existing electricity infrastructure; various wind farms (existing and proposed); sensitive ecological habitat types; areas of flood risk; areas of recreational amenity: and non-designated areas of archaeological and cultural heritage interest.

The preferred route described in this document may be subject to minor localised adjustment. Detailed design will be informed, both through this consultation exercise and through continuing detailed surveys, which may identify any as yet unknown, engineering, environmental or land use constraints which may require modifications to the route alignments before finalising the proposed route. The proposed route will then be brought forward with an application for consent.


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When providing comment and feedback, SHETL would be grateful for your consideration of the questions below:

• Is the rationale for the project clearly set out in the consultation document?

• Is the approach to the selection of the preferred route, identifying the optimum balance of technical, economic and environmental feasibility, 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 route?


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1 INTRODUCTION

1.1 About the Consultation Document

1.1.1 This consultation document invites all interested parties to comment on the proposals by Scottish Hydro Electric Transmission Limited (SHETL) to construct:

• A new replacement1 26 km double circuit 275 kV overhead line (OHL) supported by steel lattice towers between a substation at Dounreay (Dounreay substation) and a new substation currently being developed at Spittal (new Spittal substation)2, via a proposed new substation south of Thurso (new Thurso south substation)3

• A new 4 km double circuit 132 kV OHL supported by steel lattice towers between the new Spittal Substation and Mybster substation

; and

4

1.1.2 Figure 1 provides an overview of the preferred route.

.

1.1.3 The consultation document outlines the process by which the preferred route has been selected. Comments are now sought from a wide range of statutory authorities, key stakeholders, politicians and the general public on the route selection process and the preferred route described. These comments will inform further consideration of the route and the eventual selection of a proposed route for which consent will then be sought.

1.1.4 A separate ‘Scoping Report’ will be issued to consult specifically on the proposed scope of and approach to an Environmental Impact Assessment (EIA) which will be undertaken according to the provision of the Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2000 (as amended). The scoping process will be undertaken in parallel with this consultation exercise.

1.1.5 Copies of this Consultation Document have also been deposited for public viewing at the following locations:

Thurso Service Point Council Offices Rotterdam Street Thurso KW14 8AB

Caithness Planning and Building Standards Office Market Square Wick KW1 4AB

1 The proposed 275 kV overhead line will ultimately replace the existing 132 kV overhead line between Dounreay and Spittal;

2 The proposed 275 kV overhead line will connect to the new Spittal substation, which was granted planning consent in

November 2011. The substation is not the subject of this consultation and is being developed under a different project. 3 The proposed 275 kV overhead line will connect to a new Thurso South substation, approximately 1.2 km south of the

existing substation. The substation is being developed as a separate part of this project and has already been the subject of an initial consultation exercise, in early 2012 and is therefore not the subject of this consultation. Further consultations will be carried out on the substation development at a future date.

4 The proposed 132 kV overhead line will connect to an extended Mybster substation. The proposed extension to the existing

Mybster substation is part of this project but will be consulted on through a separate exercise and is therefore not the subject of this consultation report.


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Thurso Library Davidson's Lane

Thurso Caithness

KW14 7AF

Caithness Mobile Library (Wick)

1.1.6 Public consultation exhibitions will be held as follows:

• 4th July 2012 between 2pm and 7pm at Caithness Horizons, Old Town Hall, High Street, Thurso; and

• 5th July 2012 between 2pm and 7pm at Ulbster Arms Hotel, Halkirk.

1.1.7 Comments should be sent to: [email protected]

Structure of the Document

Section 1: Introduction

1.1.8 Section 1 provides an overview of the proposals and the purpose of the consultation document.

Section 2: The Proposals

1.1.9 Section 2 describes the need for the proposal, the strategic alternatives considered, the preferred route and the anticipated general design and typical construction methods.

Section 3: Route Selection Methodology

1.1.10 Section 3 sets out the route selection methodology that has been applied to date.

Section 4: Environmental Character

1.1.11 Section 4 describes the environmental characteristics of the initial route corridor within which the preferred route has been developed, based on desktop and detailed site surveys.

Section 5: Consultation on the Preferred Route

1.1.12 Based on the work carried out to date, this section reviews the preferred route and invites comments on the route and the route selection process.

1.2 The Next Stages

1.2.1 Following the completion of the consultation process, SHETL will review all comments received. Together with the assessment of environmental impacts undertaken as the EIA process, the comments will be used to develop and refine the preferred route and select a proposed route to bring forward for consent.

mailto:[email protected]�


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1.2.2 SHETL will apply for consent under Section 37 of the Electricity Act 1989 (The 1989 Act). The intention is to bring an application for consent to the Scottish Ministers in late 2012.

1.3 Statutory Consents Procedure

1.3.1 Applications for consent for the construction of OHLs are considered by the Scottish Ministers under the terms of the 1989 Act. As part of the application for consent SHETL will also request that planning permission for ancillary works associated with OHLs be deemed to be granted under section 57(2) of the Town and Country Planning (Scotland) Act 1997 (the 1997 Act).

1.3.2 Following receipt of all views and representations, the Scottish Government will determine the application for consent in one of two ways:

• Consent the proposal, with or without conditions attached; or

• Reject the proposal.

1.3.3 The new substation development at Thurso South and the new substation extension at Mybster are not part of this consultation document. The substation sites are however subject to separate consultation exercises and it should be noted that these will be the subject of applications for planning permission under the Town and Country Planning (Scotland) Act 1997. These projects are discussed further as part of the preferred network reinforcement options in paragraph 2.2.4.


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2 THE PROPOSALS

2.1 The Need for the Proposal

2.1.1 SHETL is proposing a new 275 kV double circuit OHL between the Dounreay and the new Spittal substation via the new Thurso south substation. This new OHL will replace the existing 132 kV double circuit OHL. In addition SHETL is proposing to construct a new 132 kV OHL which would run in parallel with the existing 132 kV OHL between the Spittal substation and the new Mybster substation extension.

2.1.2 This proposal is part of the reinforcement of the electricity transmission network, envisaged by the National Planning Framework (NPF2)5 and the Energy Networks Strategy Group6

2.1.3 Analysis of the existing transmission network in the north of Scotland identifies the need for increased network capacity to facilitate the transmission of renewable generation projects north of Beauly including onshore/offshore wind and marine and tidal generation. This increase in network capacity can only be achieved by undertaking reinforcement of the transmission network in the North of Scotland.

.

2.1.4 The proposal described in this Consultation Document is part of this reinforcement along with other proposed reinforcement projects that will link Caithness, Moray Firth and Shetland (CMS) by a multi-terminal high voltage direct current (HVDC link).

2.2 Alternative Options Considered

2.2.1 As transmission licence holder under section 9(2) of the 1989 Act, SHETL has a statutory obligation to:

i. develop and maintain an efficient, co-ordinated and economical system of electricity transmission; and

ii. to facilitate competition in the supply and generation of electricity.

2.2.2 In terms of Section 38 and Schedule 9 of the 1989 Act, SHETL also has statutory obligations to have regard to environmental considerations when formulating proposals for OHLs.

2.2.3 With these statutory obligations in mind, SHETL has undertaken a detailed review of the alternative options available to achieve the network reinforcement required (as described in section 2.1). This involved a review of seven network reinforcement options. The seven options were assessed against the following criteria:

• Capital cost;

• Planning and consenting risk;

• Environmental impact;

5 http://www.scotland.gov.uk/Topics/Built-Environment/planning/National-Planning-Policy/npf

6 ENSG (February 2012) ‘Our Electricity Transmission Network: A Vision For 2020’, , URL:

http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/future-elec-network/4263-ensgfull.pdf (accessed 20th March 2012)

http://www.scotland.gov.uk/Topics/Built-Environment/planning/National-Planning-Policy/npf�

http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/future-elec-network/4263-ensgfull.pdf�


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• Potential generation constraint costs;

• Capability to facilitate initial Pentland Firth marine generation development;

• Technical capacity benefit across the North of Beauly grid boundary and the North-West grid boundary;

Preferred Network Reinforcement Option

2.2.4 Following this review, the most effective network reinforcement option in terms of cost, timing and environmental impact for the Caithness area and for the wider transmission network was considered to comprise the following:

• 1) Construction of a new 275/132 kV substation and HVDC Converter Station at Spittal, approximately 4 km north of Mybster. A planning application was made to The Highland Council and consent has been approved. A voluntary EIA was undertaken and an ES was prepared as part of the planning application;

• 2) Construction of a new 400 kV extension at the existing Blackhillock substation. A planning application to The Moray Council has been submitted in 2012. A voluntary EIA was undertaken and an ES was prepared as part of the planning application;

• 3) Installation of an HVDC Link between Spittal and Blackhillock. The onshore elements of the project between Spittal and Noss Head in Caithness, and Blackhillock and Port Gordon in Moray are classed as permitted development under Town and Country Planning (General Permitted Development) (Scotland) Order 1992 (as amended) (GPDO).

• 4) Construction of a new 275 kV/132 kV substation near Cambusmore (to be known as the Loch Buidhe substation), at the crossing of the Beauly to Dounreay 275 kV and Shin to Brora/Mybster 132 kV overhead lines. A screening opinion from The Highland Council has confirmed that the Loch Buidhe substation proposals are not EIA development. Further environmental and engineering evaluation is currently underway to establish the appropriate level of voluntary environmental supporting information to support the planning application;

• 5) Construction of a 275/132kV substation (to be known as the Fyrish substation) near the existing Alness 132 kV Tee point and interface with the existing Alness Grid Supply Point. A voluntary Environmental Appraisal is currently underway and will be submitted in support of the planning application, in summer 2012;

• 6) Reconductor the existing single 275 kV circuit between Beauly and the proposed new substation at Cambusmore (c.62 km). This circuit has an existing Section 37 consent, therefore an EIA is not required;

• 7) Construction of a new Dounreay – Thurso – Spittal 275 kV OHL to replace the existing 132 kV OHL (c. 26 km), and construction of a new Thurso south substation. Environmental and engineering assessments are currently being undertaken, which will inform the EIA to be undertaken and the preparation of an ES to accompany the Section 37 consent application, and a voluntary


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Environmental Appraisal to accompany the planning application for the new Thurso south substation; and

• 8) Construction of a new 132 kV double circuit overhead line between Mybster and the new Spittal substation (c. 4 km) and construction of an extension to the existing Mybster 132/33kV substation. Environmental and engineering assessments are currently being undertaken, which will inform the EIA to be undertaken and the preparation of an ES to accompany the Section 37 application and a voluntary Environmental Appraisal to accompany the planning application for substation extension.

2.2.5 The OHL elements of Items 7 and 8 on this list form the basis of the proposal described in this Consultation Document. Substation development in support of items 7 and 8 is the subject to separate Consultation.

Alternative Line and Tower design

2.2.6 SHETL considered a series of network reinforcement options, favouring a standard steel lattice tower design solution suited to the specified network requirements, the nature of the receiving environment (including climatic conditions as well as coastal and inland topography etc) and technical compatibility with the existing network infrastructure.

2.3 Proposal Overview

2.3.1 The proposal comprises the following7,8

• Section 1: 275 kV double circuit OHL from the Dounreay substation (NGR NC 983 666) to the new Thurso South substation near Geiselittle (NGR NC 122 649);

:

• Section 2: 275kV double circuit OHL from the new Thurso South substation near Geiselittle (NGR NC 122 649) to the new Spittal substation (NGR ND 152 555);

• Section 3: 132kV double circuit OHL from the new Spittal substation (NGR ND 152 555) to the Mybster substation extension (NGR ND 169 516).

2.3.2 The preferred route is illustrated in Figure 1 and Figures 2a, b and c.

2.3.3 The route between each of the substations has been the subject of a route selection process, which has considered alternative route corridors and alternative alignments within the corridors. A brief description of each section of the preferred route is provided in section 5.

2.4 Line Design and Construction Typical Tower Design

7 References to section 1, 2 etc. are for ease of description only and do not constitute different phases or elements of the

proposal. 8 Six figure National Grid References (NGRs) are provided as approximate locations at this stage, and are subject to variation

as the design progresses. Precise locations of substation connections, line, section and angle towers are all to be confirmed later in the design process.


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2.4.1 As with the majority of high voltage OHL in the United Kingdom, the proposed 275 kV OHL between the Dounreay and the new Spittal substations and 132 kV OHL between the new Spittal substation and Mybster substation extension will be constructed using self-supporting steel lattice towers.

2.4.2 The towers used for the 275 kV OHL and the 132 kV OHL will be similar in appearance (both being steel lattice structures); however the 275 kV towers will be taller and have a larger footprint than the 132kV towers.

2.4.3 Towers along the OHL between the Dounreay and the new Spittal substations will vary in height, between a minimum of 32 m and a maximum of 52 m to accommodate changes in topography and where the line crosses roads and rivers, although the height will generally be in the region of 40 m.

2.4.4 The line between Spittal and the new Mybster substation extension will vary in height between a minimum of 23 m and a maximum of 38 m although the height will generally be in the range of 28 m.

2.4.5 Figure 3 illustrates the key characteristics and relative scales of the anticipated tower types.

2.4.6 The spacing between towers will vary depending on topography, altitude and land usage. The height and distance between towers will be determined later in the design process; however the spacing will be generally in the range of 260-360 m for the 275 kV towers and 200-300 m for the 132 kV towers.

High voltage OHL Construction

2.4.7 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;

• string conductors (wires);

• dismantle and remove temporary scaffolds and protection; and

• reinstate tower sites and remove temporary access tracks.

Access Strategy

2.4.8 Temporary tracks (or permanent, subject to necessary consents, and landowner and future maintenance requirements) capable of taking a crane and other heavy plant, including concrete deliveries, are generally required for the construction of each tower. Where ground conditions permit, it may be possible to construct the towers without an access track (e.g. on dry and level pasture). However stone roads to all towers are preferred where conductor stringing machines would be used. Matting may be used in some sensitive areas subject to an assessment of gradients and ground conditions. Helicopters may also be used to facilitate access in particularly


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sensitive or remote areas. Tracks will generally be constructed using a geotextile, with approximately 200 mm of crushed and compact stone laid on top. Tracks may be floated over areas of peat, or may use cut and fill approaches, subject to ground conditions and gradients. It is likely for most of the route, that a temporary track will be established along the route alignment with access back to the local road network, connecting at intermittent locations along the route

2.4.9 Temporary construction compounds will also be required along the route, the location of which will be determined through further on-going design works.

Foundation installation

2.4.10 A tower compound will be established at each tower location, within which foundation installation and subsequent tower erection would take place. Each compound would be fenced for safety reasons. There are three different types of foundations available, including:

• Spread type e.g. pad and chimney and pyramid and chimney;

• Piled type e.g. tube, augured shaft and micro pile; or

• rock anchor.

2.4.11 The majority of the foundations are likely to be of a spread type. However, depending on particular ground conditions, there may be the requirement to use mini-piled, auger or rock anchor foundations. Foundation types and designs for each tower would be confirmed following detailed geotechnical investigation at each tower position.

2.4.12 For the majority of towers using spread type foundations, excavations are advanced for each leg of the tower. The size of excavation will vary according to the foundation design however they are typically 3-4 m deep with excavation carried out by mechanical excavator, with rock breaking required in some locations. The foundation stub is then concreted into position using the foundation formwork.

2.4.13 After the concrete has cured, the excavations can be backfilled using the excavated materials.

Tower Assembly and Erection

2.4.14 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.

2.4.15 If the access is suitable, a crane would be used to complete the assembly and erection of the tower. If there is no vehicular access or it is unsuitable for a crane then a helicopter could be used to deliver an erection derrick, winch and ancillary equipment to site to effect the tower erection.

Conductor Stringing

2.4.16 Prior to stringing the conductors, temporary protection measures (normally netted scaffolds), will be erected for features such as roads, railways, and existing OHL which are to be crossed. The heavy plant and equipment required, including heavy towing tractors, winches, tensioners, pilot reels and conductor drums would be taken to the conductor stringing machine sites along the ground using a mixture of low-loaders and 4x4/6x6 ‘Hiab’ crane lorries.


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2.4.17 Conductor stringing equipment i.e. winches, tensioners and ancillary equipment are set up at either end of pre-selected sections of the OHL. Firstly, pilot wires are pulled through the section to be strung. The pilot wires are hung in blocks (wheels) at each suspension tower in the section and connected to a winch and tensioner at the respective end of the section. The winch in conjunction with the tensioner is used to pull the pilot wires which are connected to the conductor at the tensioner end. The conductor is pulled via the pilot wires through the section and under controlled tension to avoid contact with the ground and any under-running obstacles including protection scaffolds. Once the conductor has been strung between the ends of the section it is then tensioned to provide the necessary sag and then permanently clamped at each tower.

Construction programme

2.4.18 It is anticipated that the construction programme would last approximately 34 to 36 months. A notional start date in January 2014 would allow the completion of construction by December 2016. The detailed construction phasing and programme will be subject to change as the design progresses and also due to necessary consents and wayleaves being agreed.


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3 ROUTE SELECTION METHODOLOGY

3.1 Overview

3.1.1 The approach to route selection was informed by SHETL guidance9

3.1.2 Individual studies were undertaken for each component of the proposals to determine the technical feasibility, economic viability and any environmental constraints affecting the consideration of different route options, in consultation with key statutory consultees. These were then reviewed together to identify the preferred route that balanced each of these considerations.

, which sets out the key routeing principles for high voltage steel lattice tower transmission OHLs. The flowchart below summarises that approach.

Flowchart 1: Approach to Route Selection

9 SHETL (2004) Electricity Transmission Development Proposals in Scotland, The Scottish Hydro-Electric Transmission

Limited (SHETL) Approach. A Guidance Document Outlining the SHETL Approach to the Routeing of High Voltage Steel Lattice Tower Transmission Lines, Leading to an Application for Consent in Scotland.


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3.2 Identification of Routeing Constraints

3.2.1 The first step involved the identification of routeing constraints which informed the development of the routeing strategy, including development of route corridors and the selection of preferred corridors that would provide the required connection(s) between existing or proposed sub-stations.

3.2.2 The following requirements informed the routeing process:

• minimising the extent of new transmission assets and cost, for example, through minimising the length of new transmission OHL and the number of towers;

• reducing angles of deviation to a minimum, of approximately 60°;

• minimising electricity outages on the existing transmission and distribution networks during construction;

• the interaction of the proposals with existing infrastructure and with other proposed transmission projects in the vicinity;

• ensuring a direct approach for substation line entries, as far as possible;

• minimising construction effort on-site;

• the preference to avoid specific mid route underground sections;

• land ownership boundaries and grantor requirements;

• opportunities to avoid crossing linear features as much as possible, for example, roads, railway lines, rivers;

• general landscape and visual amenity (backcloth and screening);

• opportunities to mitigate the wirescape of the area and to minimise 'new' visual impact by following the routes of existing electricity infrastructure wherever possible;

• minimising land-take, or severance, of existing agricultural land;

• minimising impact on traffic and access;

• opportunities to avoid areas of residential amenity such as residential dwellings and curtilages;

• minimising impacts on sensitive environmental features10

10

Sensitive environmental features are defined in the SHETL guidance as including:

, including sites designated for ecological protection, risk of flooding, visual amenity, and cultural heritage value; and

- Special Areas of Conservation (SACs); - Special Protection Areas (SPAs); - Ramsar Sites; - National Scenic Areas; - National Parks; - National Nature Reserves; - Protected Coastal Zone Designations; - Sites of Special Scientific Interest (SSSIs); - Scheduled Ancient Monuments;


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• known information on proposed wind farms.

3.2.3 Section 4 of this consultation document describes the environmental sensitivities considered in formulating the Preferred Route in more detail.

3.3 Routeing Strategy: development of route corridors

3.3.1 The second step involved the development of route corridor options. This was achieved through understanding the nature and extent of key routing constraints in greater detail, using a combination of desk based and site based assessment.

3.3.2 A route corridor options appraisal was undertaken by SHETL in April 201111

3.3.3 The appraisal involved the following:

, which considered various options for the reinforcement of the transmission network in Caithness, including, but not limited to the 275 kV / 132 kV Dounreay substation to Mybster OHL. The appraisal considered a number of 2 km-wide corridor options for the 275 kV circuit, taking into account the technical requirement to connect to the existing network at Thurso.

• Environmental routing constraints - constraints identified from desk sources were mapped across the study area;

• Options mapping and data gathering - the corridor options were overlaid on the constraints maps, with additional data on topography, settlements, roads and paths considered;

• Initial options appraisal and consultation - SEPA, SNH and The Highland Council were consulted on the corridor options and implications;

• Site reconnaissance - site visits were made to establish current land uses, broad habitat types and likely visibility, to ground truth the desk based appraisal, and to determine the technical feasibility of the options;

• Options appraisal - corridor options were assessed based on the suitability to accommodate a new OHL, taking factors such as topography, accessibility, land use, visual amenity, environmental character, into account ;

• Recommendations. Corridor options were compared on the basis of technical constraints, constructability, cost and environmental character, and preferred corridors selected for further consideration.

- Listed Buildings; - Conservation Areas; - World Heritage Sites; and - Historic Gardens and Designated Landscapes.

11 Natural Capital (April 2011) Caithness Connections: Strategy for Reinforcements


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3.4 Development of Route Options Analysis and Comparison of Route Options

3.4.1 The third step involved an iterative process of analysis and comparison of the route alignment options within the route corridors, as follows:

• Option 1 - the initial stage identified a base case route option selected on the basis of:

- build-ability,

- cost,

- minimisation of new transmission asset requirements; and

- minimisation of electricity outages during construction.

• Option 2 - the second stage considered alternative alignments to Option 1 at specific locations along the route in order to:

- minimise crossing of linear features, such as roads, railway lines and rivers;

- avoid residential dwellings and other sensitive properties (such as schools); and

- avoid disruption to land owners and existing land use (such as farming) by seeking to follow field boundaries as far as practicable;

• Option 312

3.4.2 Figures 4 a, b and c illustrate the different route options considered. The outcome of the analysis and comparison of the route options led to the selection of the preferred route.

– this stage considered alternative alignments to both Options 1 and 2 at specific locations along the route, to minimise any potential environmental impact, having regard to the Holford Rules and the desirability of avoiding important physical, natural and built environment assets.

12

Note. Whilst we refer here to options, these stages describe the evolution of the route selection process; the options presented represent iterations of the design rather than design alternatives.


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4 ENVIRONMENTAL CHARACTER

4.1 Introduction

4.1.1 The information provided in the following section, provides a description of the key environmental sensitivities within the study area13

4.2 Landscape (including topography, landform and settlement patterns)

. The significance and relevance of each of the sensitivities to the proposals are also highlighted where appropriate.

4.2.1 There are no areas of Highest Amenity Value for landscape or visual amenity within 10 km14

4.2.2 There are a small number of Less Important landscape and scenic designations within 10 km of the preferred route, as follows:

of the preferred route (i.e. National Scenic Areas, National Parks, World Heritage Sites).

• Dunnet Head Special Landscape Area (SLA);

• The Flow Country and Berriedale Coast SLA; and

• A Search Area for Wild Land (SAWL),

4.2.3 In addition Farr Bay, Strathy and Portskerra SLA lies just outside the 10 km radius, to the west.

4.2.4 The principal landscape character types found along the preferred route include:

• Open Intensive Farmland;

• Mixed Agriculture and Settlement; and

• Coniferous Forest.

4.2.5 Given the generally flat and sparsely planted landscape, close attention was given to the Holford Rules during the route selection process. The aim was to design out potential significant landscape and visual impacts. The preferred route has generally taken the most direct line, avoiding sharp changes of direction where possible. The preferred route between the new Thurso south and new Spittal substations was selected west of the river on the grounds that it would be more remote from the A9 and would benefit to a large extent from backclothing of rising ground to the west.

4.2.6 By generally following the existing 132 kV OHL from Dounreay to Spittal (which would be removed following the completion of the 275 kV OHL), the preferred route minimises potential wirescape effects and 'new' visual impact.

13

The study area is the area of land, at its widest extent, which was considered within the route selection process. Defined here as the broad area between Dounreay to the west, Thurso to the east, the coast to the north and Mybster to the south

14 Given the nature and scale of the proposed steel lattice tower lines, it is considered unlikely that significant landscape and visual effects would be experienced at distances in excess of 10 km from the line. This is in accordance with guidance contained in I. McAulay and M. Turnbull (2008) Wood Pole Transmission and Distribution Lines in Rural Landscapes: Perceptibility.


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4.3 Ecology and Ornithology

4.3.1 The study area is dominated by improved grassland fields with occasional areas of wetland, coniferous plantation and waterbodies. The majority of the preferred route avoids all areas of highest ecological amenity value i.e. Special Areas of Conservation (SAC), Special Protection Areas (SPA), Ramsar Sites, National Nature Reserves and Sites of Special Scientific Interest (SSSI). The exception is where the route is required to cross the River Thurso, which is designated as an SAC and SSSI. Sites designated for ecological protection are marked on Figures 5a, b and c.

4.3.2 The preferred route runs in close proximity (< 1 km) to a small number of designated sites. The route runs to the north of the Loch Lieurary SSSI, designated for its basin fen habitat, and the Westfield Bridge Site of Special Scientific Interest (SSSI), notified for its nationally important fen meadow and calcareous grassland vegetation.

4.3.3 It runs in close proximity (< 1 km) to a small number of features, which while not designated for ecological value, are considered to be sensitive. An undesignated small waterbody, Loch Achbuilligan, located south of the preferred route has the potential to support otter or water vole, both of which are European Protected Species. South of Spittal there is an area of undesignated, but sensitive wet modified bog around Achanarras Quarry geological SSSI. There is an area of young plantation broad leaved woodland at the B870, and there are patches of mire habitat in close proximity to the new Mybster substation extension.

4.3.4 An ornithological survey is currently being undertaken within a 2 km corridor which includes the preferred route. Much of the study area contains geese foraging and roosting areas. The Forss Water is a locally known corridor for Greenland White-fronted geese and other wildfowl commuting between roost and foraging sites. Baillie Hill is also a key location for geese and wildfowl. There are potential flight corridors from Broubster Leans SPA/SAC/Ramsar/SSSI, designated for whooper swan Cygnus cygnus, Greenland white-fronted goose Anser albifrons and greylag goose Anser anser, within the south western part of the study area, and Loch Calder SPA/Ramsar/SSSI, designated for the same species.

4.3.5 Areas of suitable habitat for upland raptors occur at Hill of Shebster; Baillie Hill, Moss of Geise and the moorland around Fryster. The peatlands and heaths at Forsie, Hill of Lieurary, Hill of Calder and Yellow Moss appear suitable for use by raptors such as Hen harrier Circus cyaneus, merlin Falco columbarius and short-eared owl Asio flammeus and wading bird species such as golden plover Pluvialis apricaria. The area between Spittal Hill and Watten also provides potential passage locations for wading birds.

4.4 Cultural Heritage

4.4.1 Only one Scheduled Ancient Monument (SAM) and a small number of features of lesser importance have been identified within 50 m of the preferred route. The SAM is a scheduled broch of Cnoc Urray, which survives as a turf-covered mound with some stone visible. This area would be marked off and safeguarded during construction. No other designated or notable features have been identified.

4.4.2 The preferred route falls within 1 km of 19 SAMs and seven listed buildings, however while there is the potential for effects on settings of these features; it is considered unlikely for there to be any direct impact.


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4.5 Geology, Hydrogeology, and Hydrology Geology

4.5.1 The preferred route avoids designated geological sites, and former quarry sites (for geotechnical reasons). There is one site, Achanarras Quarry SSSI south west of Spittal within a 1 km radius designated for geology and vertebrate palaeontology.

Hydrogeology

4.5.2 The BGS Hydrogeology and Groundwater Vulnerability Maps (1: 625 000) indicate that the site is underlain by a moderately permeable aquifer. While the Upper Caithness Flagstone Group will seldom produce large quantities of water for abstraction, it is important for local supplies and for supplying base flow to rivers. Within the Caithness area the bedrock is classified as a locally important aquifer, and groundwater is largely confined to a shallow zone of weathered rock and borehole yields are limited. The local bedrock and sand and gravel aquifers are designated by SEPA as a drinking water protection zone. While this will not constrain the route selection, mitigation measures will be required during construction to ensure that there is no significant environmental effects arising from potential ground water pollution or abstraction (in the event of dewater excavations).

Hydrology

4.5.3 The preferred route crosses the Dounreay Burn, Forss Water and the River Thurso (at two locations), and some other small burns. However, given the likely span length, their presence has not materially influenced the route selection process.

4.5.4 The Dounreay burn and River Thurso were classified in 2008 by SEPA15

4.5.5 Flood risk areas have been identified with reference to the Scottish Environment Protection Agency (SEPA) online flood risk mapping

under the Water Framework Directive as having overall ‘Good’ status. The Forss Water was classified overall as ‘Poor’ due to abstractions, although the chemical status remains good. The Forss water is protected for freshwater fish. While these watercourses do not represent a material constraint to route selection, mitigation measures will be required during construction to ensure that there is no significant environmental effect.

16

4.5.6 The following properties have private water supplies, as registered with The Highland Council:

, which shows the area at risk of flooding in the 1 in 200 year flood event. Towers will be located to avoid the flood risk areas; however the potential for flooding does not compromise the safe operation of the OHL. In general, the design will seek to avoid any construction within 50 m of watercourses.

• Achnabrae, Skaill;

• Knockglass Farm, Westfield;

• Lieurary Mains, Westfield; and

• Cathel Sheiling, Cathel, Halkirk.

15

http://www.sepa.org.uk/water/river_basin_planning.aspx 16

http://go.mappoint.net/sepa/, accessed 16.01.2012

http://www.sepa.org.uk/water/river_basin_planning.aspx�

http://go.mappoint.net/sepa/�


Page 17

4.5.7 In addition, Knockglass spring is registered with The Highland Council as the location of the private water supply to Knockglass Farm.

4.5.8 Registering a domestic private water supply with the local authority is not currently a mandatory requirement therefore it is possible that additional unregistered private water supplies exist. Private Water Supplies do not represent a material constraint to route selection; however they would require protection from pollution during construction.

4.6 Soils, land use and agriculture

4.6.1 In general, the study area comprises improved grassland fields and pastures with occasional marshland, moorland and waterbodies. The Land Capability for Agriculture map system17

4.6.2 Within the route corridors, there are various areas of Grade 3 Agricultural Land, located as follows:

grades land in terms of its suitability for agriculture. Grades 1, 2 and 3 agricultural land are considered capable of producing a moderate to very high range of crops, and are treated as sensitive areas, while grades 4, 5, 6 and 7 are noted as only suitable for producing a narrow range of crops, or for use as grazing land and are not sensitive to development.

• at either side of the River Thurso: are areas noted as having soil and/or climate limitations and cover the surroundings of Geise and Upper Geiselittle;

• the area around Calder Holdings and southwards to Achavrole.

4.6.3 The preferred route avoids the majority of grade 3 agricultural land.

4.7 Forestry and Woodland

4.7.1 There are occasional patches of Forestry Commission and other plantation woodland within the study area, however the preferred route avoids the need for substantial woodland removal.

4.8 Transportation and Infrastructure

4.8.1 The mainline railway link to Wick crosses the study area south of Halkirk and branches off north to Thurso.

4.8.2 Various roads cross the study area, the largest of which are as follows:

• the A836 south east of Lower Dounreay, between Balmore and Isauld;

• the B870 south of Thurso, between Glengolly and West Calder, and east of Loch Calder between West Calder and Olgrinmore;

• the B874 south of Thurso, which forks east of the B870 and runs between Glengolly and Aimster, and west of Brabsterdorran between Corsback and Lynegar;

• the A9 south of Thurso, between Thurso and Bulliemore, and south east of Halkirk between Achalone and Spittal; and

17

Soil Survey of Scotland (1987) Sheet 12: Thurso and Wick


Page 18

• the A882 south east of Halkirk between Gelshfield and Oldhall Ho.

4.8.3 In addition, there are minor roads throughout the study area. The route selection process has sought to minimise crossings of transportation routes.

4.8.4 The existing electricity distribution/transmission OHL within the study area comprise low voltage (LV), 11 kV, 32 kV and 132 kV OHL circuits which may require to be diverted or undergrounded as part of the proposals to facilitate the installation of the new 275 kV and 132 kV OHL.

4.8.5 There are also two water treatment works within the study area; one west of Shebster and a second at Calder Bridge, south of Westfield. Neither will be affected by the preferred route.

4.9 Socio-Economics, Recreation and Tourism

4.9.1 The following recreation and tourism sites are identified within the route corridor:

• National Cycle Route No. 1, which runs from Dounreay to Thurso and around the coast to Gills Bay;

• woodland walks at Achvarsadal Wood , Reay;

• the River Thurso, which is popular for salmon fishing; and

• Loch Calder, which is popular for trout and charr fishing.

4.9.2 A number of Core Paths also fall within the study area, as identified within the Highland Council Core Paths Plan18

4.9.3 The preferred route has been selected to minimise impacts on tourism and recreation. There is the potential for some temporary disruption during the construction programme; however by following the existing tower line infrastructure the preferred route ensures that there will be no permanent or long term effects on these sites.

.

4.10 Proposed New Development

4.10.1 The following wind farm or single wind turbine sites within the study area are also proposed19

• South Shebster: 9-turbine wind farm; application refused;

:

• Baillie Hill: 21-turbine wind farm; consented;

• Hill of Forss: wind farm at the design and feasibility stage;

• Hill of Lieurary: 2-turbine wind farm; awaiting determination;

• Spittal Hill: 30-turbine wind farm; application refused;

• Halsary: 18-turbine wind farm; awaiting determination.

18

Highland Council Core Paths Plan, adopted 21 September 2011 19

Taken from The Highland Council Wind Farm Activity Map, Feb 2012


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5 CONSULTATION ON THE PREFERRED ROUTE

5.1 Route Selection Process

5.1.1 The objective of the route selection process has been to identify a technically feasible (both in terms of constructability and long term maintenance), economically viable transmission route, between defined points, which give 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 and other economically beneficial uses of land.

5.1.2 The assessment has been based on:

• detailed baseline data on land use and environmental character and sensitivity, obtained from desk sources and site reconnaissance;

• 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.

5.1.3 A preferred route has been identified, which on the basis of the route selection process is considered to represent the optimum balance of technical, economic and environmental feasibility.

5.2 The Preferred Route

5.2.1 This section provides a description of the preferred route, as shown in Figures 2a, 2b and 2c. 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.

Section 1

5.2.2 Section 1 of the preferred route follows an alignment between the Dounreay substation (NGR NC 983 666) and the new Thurso South substation at a location near Geiselittle (NGR ND 122 649). Section 1 is illustrated by Figure 2a.

5.2.3 The alignment runs parallel to and approximately 90 m north of the existing Dounreay-Mybster 132 kV OHL from Dounreay, until it reaches the crossing of the B870 at Moss of Geise (NGR ND 099 646). The preferred route traverses on to the south side of the existing 132 kV line at this point, turning slightly to the north east to cross the railway line and River Thurso at a point approximately 350 m south of the existing 132 kV OHL, terminating in a new substation (Thurso South) near to Geiselittle (NGR NC 122 649).


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5.2.4 The preferred route currently includes a short alternative alignment through the eastern part of the Bailie Hill wind farm site, deviating from the existing 132 kV line to the north from NGR ND 028 649, passing approximately 250 m south of Hill of Stemster broch, and re-joining the route parallel to the existing 132 kV line west of the minor road to Baillie farm at NGR ND 048 647. The eventual alignment will be determined following more detailed survey.

Section 2

5.2.5 Section 2 (Figure 2b) follows a route between the new Thurso South substation near Geiselittle (NGR NC 122 649) and Spittal substation (NGR ND 152 555).

5.2.6 It initially runs south east from the proposed new Thurso South substation before turning southwards at Todholes Farm to cross the railway line and River Thurso, crossing to the western bank of the river at NGR ND 125 633. It then turns to the south east to re-cross the river approximately 500 m north of Hoy and Braal Holdings (at NGR ND 137 616) before turning to run north to south at NGR ND 143 611, from where it runs parallel to the existing 132 kV OHL until it reaches the new Spittal substation.

Section 3

5.2.7 Section 3 (Figure 2c) runs between the new Spittal substation (NGR ND 152 555) and the existing Mybster substation (NGR ND 169 516).

5.2.8 This section runs in parallel to the existing Dounreay-Mybster 132 kV OHL, on the east side. The existing 132 kV OHL would remain in use between Spittal and Mybster following construction of the proposed 132 kV OHL.

5.3 Questions for consideration by consultees

5.3.1 When providing comment and feedback, SHETL would be grateful for your consideration of the questions below:

• Is the rationale for the project clearly set out in the Consultation Document?

• Is the approach to the selection of the preferred route, identifying the optimum balance of technical, economic and environmental feasibility, 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 route?


Annex A: Figures

Figure 1: Preferred Route Overview (1:250k @ A3)

Figure 2 a, b and c: Preferred Route (1:50k @ A3)

Figure 3: Indicative Tower Designs

Figure 4 a, b and c: Route Options

Figure 5 a, b and c: Environmental Constraints (1:50k @A3)

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