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Aultbea to Dundonnell 33kV Overhead Distribution Line Upgrade Environmental Statement Volume 1 Written Statement December 2009 By: For: AULTBEA TO DUNDONNELL 33kV DISTRIBUTION LINE UPGRADE ENVIRONMENTAL STATEMENT DECEMBER 2009 ash design+assessment 21 Gordon Street Glasgow G1 3PL Tel: 0141227 3388 Fax: 0141 227 3399 email: [email protected] www.ashdesignassessment.co Scottish and Southern Energy Aultbea to Dundonnell 33kV Distribution Line Upgrade Environmental Statement PREFACE Scottish Hydro Electric Power Distribution Plc (SHEPD) are proposing to replace the existing 11,000 volt wood pole overhead distribution network between Aultbea and Dundonnell. The existing overhead line is 58km including the existing spurs and provides electricity to 344 customers. It is one of the last remaining cadmium copper overhead line circuits on the exposed west coast of Scotland and is considered to be a high priority for major refurbishment due to unacceptable physical condition and poor system performance. The majority of the overhead line was built in 1950 to a light duty, long span specification using 3/.093 (.017sq in) cadmium copper conductors. The circuit is three phase (three wire) for the first few kilometres from Aultbea to Laide and part way along the Opinan 11,000 volt spur. The remainder of the circuit is single phase (two wire). The original line was extended from Dundonnell Forest to Eilean Darroch in 1956 and then on to Dundonnell House in 1958. These sections of line incorporate shorter span lengths and use 3/.104 (.025sq in) copper conductors. The circuit has suffered 20 faults over the last 5 years. The majority of faults on this circuit relate to age, deterioration and under-design. These statistics exclude the interruption associated with an exceptional circumstance on 11th January 2005 when a severe storm caused multiple faults throughout the circuit. This single incident reinforces an underlying concern that the circuit is no longer fit for purpose when considering its design strength, in context with the weather zone for this area. It is proposed to replace the original cadmium copper 11,000 volt overhead lines between Aultbea Substation and Dundonnell using the Company’s COP7 design specification. In line with the long term strategy, the main line would be constructed using 3x100mm2 copper conductors and incorporates 33,000 volt insulation. The shorter spur lines would be rebuilt using 2x25mm2 copper conductors and 33,000 volt insulation with the longer spur lines using 2x25mm2 copper conductors and 11,000 volt insulation. The latter would be supplied using 33/11kV ‘step-down’ transformers in the future. The overall project cost is estimated at £1600k. The completed project would provide an extremely robust circuit providing significantly improved reliability and supply quality to 344 customers along this exposed coastal route. This Environmental Statement documents the findings of the environmental impact assessments undertaken during the preliminary design of the proposal and during formal assessment of the proposed route and its associated design, construction and management proposals. 1 Scottish and Southern Energy Aultbea to Dundonnell 33kV Distribution Line Upgrade Environmental Statement 2 Scottish and Southern Energy Aultbea to Dundonnell 33kV Distribution Line Upgrade Environmental Statement CONTENTS PART ONE - INTRODUCTION AND BACKGROUND ............................................... 8 1 INTRODUCTION AND BACKGROUND ........................................................................... 8 1.1 Background to the Scheme ............................................................................................... 8 1.2 Statutory Obligations......................................................................................................... 8 1.3 Consent Requirements ..................................................................................................... 9 1.4 The Environmental Statement ........................................................................................... 9 1.5 The Environmental Statement Requirements ...................................................................10 1.6 Structure of the Environmental Statement ........................................................................11 1.7 Consultations ...................................................................................................................12 PART TWO – ALTERNATIVES AND THE PROPOSED ROUTE ............................ 14 2 ALTERNATIVES .............................................................................................................14 2.1 Introduction ......................................................................................................................14 2.2 Project Components and Support Structure .....................................................................15 2.3 Underground Routing .......................................................................................................15 2.4 Route Options ..................................................................................................................16 2.5 Construction ....................................................................................................................17 2.6 Mitigation Measures .........................................................................................................17 2.7 De-commissioning ...........................................................................................................18 PART THREE – ASSESSMENT OF ENVIRONMENTAL EFFECTS........................ 20 3 LANDSCAPE CHARACTER ...........................................................................................20 3.2 Study Area .......................................................................................................................20 3.3 Potential Impacts .............................................................................................................20 3.4 Method of Assessment ....................................................................................................21 3.5 Baseline Conditions .........................................................................................................25 3.6 Mitigation Measures .........................................................................................................34 3.7 Assessment of Environmental Effects ..............................................................................34 3.8 Summary and Conclusions ..............................................................................................40 4 VISUAL IMPACTS ..........................................................................................................42 3 Scottish and Southern Energy Aultbea to Dundonnell 33kV Distribution Line Upgrade Environmental Statement 4.1 Introduction ......................................................................................................................42 4.2 Study Area .......................................................................................................................42 4.3 Potential Impacts .............................................................................................................42 4.4 Statutory and Planning Context ........................................................................................42 4.5 Method of Assessment ....................................................................................................43 4.6 Baseline Conditions .........................................................................................................46 4.7 Assessment of Visual Effects ...........................................................................................46 4.8 Summary and Conclusions ..............................................................................................49 5 ECOLOGY ......................................................................................................................52 5.1 Introduction ......................................................................................................................52 5.2 Methodology ....................................................................................................................52 5.3 Policy...............................................................................................................................59 5.4 Baseline ..........................................................................................................................65 5.5 Impact Assessment..........................................................................................................75 5.6 Mitigation .........................................................................................................................77 5.7 Residual Impacts .............................................................................................................80 5.8 Limitations and Assumptions ............................................................................................81 5.9 Compliance with Legislation and Planning Policy .............................................................82 5.10 CONCLUSION .................................................................................................................82 6 CULTURAL HERITAGE AND ARCHAEOLOGY .............................................................84 6.1 Background .....................................................................................................................84