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Vattenfall Wind Power Ltd Kentish Flats Offshore Wind Farm Extension Application for Development Consent Order Grid Connection Statement and Cable Details Document Reference Number 6.1

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Vattenfall Wind Power Ltd

Kentish Flats Offshore Wind Farm Extension

Application for

Development Consent Order

Grid Connection Statement and Cable Details

Document Reference Number 6.1

- i - Kentish Flats Offshore Wind Farm Extension October 2011 Document: Grid Connection Statement and Cable Details

Company Org Doc Status Version

Vattenfall Wind Power Ltd WW-QP Report Approved Ap1

Project Author Reviewed by Kentish Flats Offshore Wind Farm Extension

Åke Larsson Louise Pepper

Doc Reference Number Date Approved by

6.1 October 2011 Göran Loman

Title

Grid Connection Statement and cable details

Distribution

Regulation 5(2) Reference

5(2)(q) and 6(1)(b)(i)

Address

Vattenfall Wind Power Ltd First Floor 1 Tudor Street London EC4T 0AM

- iii - Kentish Flats Offshore Wind Farm Extension October 2011 Document: Grid Connection Statement and Cable Details

Table of Contents

Summary

1 INTRODUCTION 1

2 BACKGROUND TO GRID CONNECTION 5

3 GRID CONNECTION FOR KENTISH FLATS EXTENSION PROJECT 6

4 CONSENTING OF GRID CONNECTION 11

5 DESCRIPTION OF THE GENERATION 12

6 INSTALLATION AND CONSTRUCTION DETAILS 13

7 STATUS OF GRID CONNECTION 17

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- vii - Kentish Flats Offshore Wind Farm Extension October 2011 Document: Grid Connection Statement and Cable Details

SUMMARY

1 This document is submitted on behalf of Vattenfall Wind Power Ltd in support of its application to construct and operate the Kentish Flats Offshore Wind Farm Extension. The Kentish Flats Extension will comprise 10 to17 wind turbines.

2 The Kentish Flats Extension is located on the southern side of the Outer Thames Estuary off the North Kent coast adjacent to the existing Kentish Flats wind farm. The existing wind farm has an installed capacity of 90MW and the proposed development will be up to 51MW.

3 The electricity generated by the existing Kentish Flats scheme is connected to the local 33kV distribution network through UK Power Networks (UKPN) Red House substation. The Kentish Flats Extension will connect into the same substation. Generated power from the Extension will be brought onshore in the vicinity of Hampton Pier, by 33 kV submarine cables. The submarine cables will be jointed to conventional 33kV XLPE insulated cables at a cable transition pit located in the Hampton Pier car park. The onshore cables deliver the power from Hampton Pier to the Red House 132/33kV substation.

4 The grid connection for the Kentish Flats Extension is made up of two elements, the offshore works and the onshore works. All the offshore works, and the onshore works up to and including the cable transition pit are included within the development consent order application. The remainder of the onshore works from the transition pit to the Red House substation will be the subject of a separate planning application to Canterbury City Council.

5 The offshore grid connection works comprise the inter-array and export cables. Both cables will be buried within the seabed. The inter-array cables connect the turbines together and the export cables will take the electricity generated to shore.

6 The onshore cables will be installed underground following, broadly, the route of the existing Kentish Flats grid connection to the Red House substation. As these works will be the subject of a separate planning application detail is provided on them for information only.

7 A feasibility study was undertaken by UKPN on behalf of Vattenfall during 2011 to investigate available connection options within

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UKPN’s network. The feasibility study showed several possible options to connect to the Red House substation. Vattenfall submitted an application to UKPN on 18 August 2011 for a connection for the Kentish Flats Extension to the Red House substation. It is expected that a grid connection offer will be received during November 2011.

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1 Introduction

1.1.1 This Grid Connection Statement and Cable Details (the "Statement") is submitted on behalf of Vattenfall Wind Power Ltd ("Vattenfall") and relates to its proposal to construct and operate the Kentish Flats Offshore Wind Farm Extension ("Kentish Flats Extension"). The Kentish Flats Extension will be a generating station comprising 10 to 17 wind turbines with an installed capacity of up to 51 MW. The Kentish Flats Extension is located on the southern side of the Outer Thames Estuary off the North Kent coast, and its location is shown in Figure 1.

1.1.2 The existing wind farm has an installed capacity of 90MW and the proposed development will be up to 51MW. As the total capacity will exceed 100MW the project is a Nationally Significant Infrastructure Project ("NSIP") under sections 14(1)(a) and 15(3) of the Planning Act 2008 and requires an application to be made to the Infrastructure Planning Commission (the "IPC").

1.1.3 This Statement is part of a suite of documents which accompany the application to the IPC (the "Application") submitted in accordance with Section 37 of the Planning Act and Regulations 5 and 6 of the Infrastructure Planning (Applications: Prescribed Forms and Procedures) Regulations 2009 (the "APFP Regulations"). The Application seeks the making of the proposed Kentish Flats Extension Order, which would confer the powers sought to construct and operate the Kentish Flats Extension.

1.1.4 This Statement has been prepared pursuant to Regulations 5(2)(q) and 6(1)(b)(i) of the APFP Regulations. Whilst it is not a requirement for a grid connection statement to be produced for an offshore wind farm it is considered that this Statement will assist in the determination of the Application. Details of the proposed cable route and installation methods are required by the APFP Regulations and these are provided in this document and in the Project Design Statement (Document 7.2).

1.1.5 This Statement addresses who will be responsible for designing and building the connection to the electricity distribution network for the Kentish Flats Extension and provides details of the proposed offshore and onshore cable route and cable installation methods.

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1.1.6 No separate glossary has been produced for this statement, as the Glossary for the Environmental Statement (Document 4.2) is appropriate.

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2 Background to Grid Connection

2.1.1 Electricity in the Herne Bay area is supplied by UK Power Networks Ltd (“UKPN”), who are the relevant Distribution Network Operator ("DNO") pursuant to an electricity distribution licence issued in accordance with the provision of the Electricity Act 1989 (as amended by the Utilities Act 2000).

2.1.2 The existing 90MW Kentish Flats Offshore Wind Farm is situated approximately 10 km from Herne Bay. Generated power is brought onshore at Hampton Pier, by three 33 kV submarine cables (see Figure 1).

2.1.3 The submarine cables are jointed to conventional 33kV XLPE (cross linked polyethylene) insulated cables at a cable transition pit located in the Hampton Pier car park. The onshore cables are installed within the public highway and deliver the power from Hampton Pier to the Red House 132/33kV electricity substation where they are terminated into a 33kV switchgear. The locations of the existing onshore cables and the Red House substation are shown on Figure 3.

2.1.4 The electricity generated by the existing Kentish Flats scheme is imported to the local 33kV system through UKPN switchgear. If generation exceeds local demand, power is exported at 132kV into the wider distribution system.

2.1.5 The Red House substation provides three basic functions:

(a) It is a grid site supplying the local 33kV network;

(b) It imports electricity generated by the Kentish Flats Wind Farm; and

(c) It provides electricity to the Kentish Flats Wind Farm.

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3 Grid Connection for

Kentish Flats Extension Project

3.1.1 The grid connection for the Kentish Flats Extension is made up of two elements, the offshore works and the onshore works.

3.2 Offshore Works

3.2.1 The wind turbines will be connected to each other and to the export cable(s) via inter-array cables. The total length of the inter-array cabling will be approximately 12km. Indicative layouts are shown on Figure 2 but the final arrangement of the inter-array cabling will be determined as part of the final project design process and details being provided to the Marine Management Organisation (the "MMO") in accordance with the requirements of the marine licence.

3.2.2 Up to two export cables will be required to bring the electricity generated to shore and these will each extend for up to 9km from the turbine array to the cable landfall as shown on Figure 2.

3.2.3 The cable(s) will be installed from one or two of the new turbines and run parallel to the existing export cables, to the cable landfall point at or adjacent to Hampton Pier, as is the case for Kentish Flats.

3.2.4 The offshore export cables will be buried up to 1.5m into the seabed using a plough or a jetting device.

3.2.5 The size of the Kentish Flats Extension and the connection to the local distribution network means the cables will operate at a voltage of 33 kV with no requirement for an offshore substation.

3.2.6 Further detail on the offshore cable works is included in section 5.17–5.21 of the Project Design Statement (Document 7.2).

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3.3 Onshore Works

3.3.1 The onshore works extend for approximately 2.4km from the cable landfall to the Red House electricity substation (Figure 3).

3.3.2 The offshore export cables will come ashore at a point near Hampton Pier at the western end of Herne Bay (in the vicinity of the existing Kentish Flats cable landfall). The cables will be jointed to the onshore trefoil cables in a cable transition pit located in the Hampton Pier car park. From here the cables will be installed underground within the public highway following, broadly, the route of the existing Kentish Flats cables inland to the Red House substation, where the connection to the grid will be achieved.

3.3.3 The export cables will be installed beneath the coastal defences and the beach at Hampton Pier using horizontal directional drilling (HDD) with the cable pulled through ducting, as was the case for Kentish Flats.

3.3.4 Vattenfall’s application to the IPC only covers the works as far as the cable transition pit. The remainder of the onshore cable works will be the subject of a separate planning application to Canterbury City Council. Detail is provided on those works for information only.

3.3.5 The onshore cables will be installed underground wherever possible within the public highway in a similar manner to the cables already in-situ for Kentish Flats, with burial below the road surface and subsequent full re-instatement. Further detail on the onshore grid connection works is provided in section 6 of the Project Design Statement (Document 7.2).

3.3.6 The connection to the Red House substation will be made by extending the existing UKPN switchboard in the UKPN switchroom by one circuit breaker panel, adding a standalone two-panel switchboard and cabling between the two switchrooms.

3.3.7 Only minor internal works will be needed to the existing Kentish Flats switchroom to accommodate the two-panel switchboard as existing spare cable ducts can be utilised in the cable basement of the building.

3.3.8 Vattenfall will be responsible for designing, building, installing, testing and energising the offshore export cables from the turbine array to the

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cable transition pit and may also take responsibility for the onshore cables from the transition pit to the Red House substation.

3.3.9 UKPN will be responsible for designing, building, installing, testing and energising the circuit breaker and switchboard at Red House substation, and in the event that Vattenfall does not take responsibility for the onshore cables from the transition pit to the Red House substation, for these works as well.

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4 Consenting of Grid Connection

4.1 Offshore Works −−−−

from Turbine Array to Onshore Transition Pit

4.1.1 The inter-array cables and export cables are included within the development consent order (DCO) application to the IPC. The inter-array cables form Work No 1b, (Work No 1a being the turbine array), the export cables Work No 2a and the transition pit and associated cabling Work No 2b. The export cables and the transition pit are considered to be "associated development" within section 115 of the Planning Act 2008 in that they are not a project in themselves but are required to export the electricity generated by the turbines and to connect the export and onshore electricity cables.

4.1.2 Indicative details and locations are provided on Documents 2.2 - 2.5 for each of the numbered Works, however these Works are each subject to the limits of deviation shown on the Works Plan (Document 5.4). In respect of the transition pit, the location and detailed specification of these works must be approved by Canterbury City Council prior to any works commencing.

4.2 Onshore Works −−−−

from Transition Pit to Electricity Substation

4.2.1 Although it would have been possible to do so, Vattenfall has decided not to include the onshore grid connection works within the Kentish Flats Extension DCO and instead they will be the subject of a separate planning application to Canterbury City Council. This was the approach taken for the original Kentish Flats scheme, and is considered appropriate for the extension project. This is considered to put more control over the works into the hands of Canterbury City Council as the local planning authority and Kent County Council as the highways authority. This application will run concurrently with Vattenfall's application to the IPC. A highways licence from Kent County Council is also required to authorise the laying of the cables within the public highway.

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5 Description of the Generation

5.1.1 The Kentish Flats Extension will be a generating station comprising 10 to 17 wind turbine generators with an installed capacity of up to 51MW.

5.1.2 The wind turbine generators will generate electricity at approximately 1kV which will be increased to 33kV for export. A step up transformer will be provided in each wind turbine to enable this. More details on the turbines and their installation is provided in section 5.14 of the Project Design Statement (Document 7.2).

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6 Installation and Construction Details

6.1 Vattenfall Works

6.1.1 All onshore and offshore construction operations will comply with all relevant legislation and guidance, including Health and Safety at Work Act (1974), the Construction Design and Management (CDM) Regulation (2007) and the Management of Health and Safety at Work Regulations (1999).

6.2 Vattenfall Offshore Works

6.2.1 The offshore cables (both the inter-array and export cables) will be installed from a barge. The barge will be equipped with specialist cable handling equipment and will have a support vessel in attendance as necessary. The cables will be stored on reels or on deck aboard the barge and will be deployed onto the seabed using cable handling equipment.

6.2.2 The offshore export cables will be installed in ducts as they approach shore in the inter-tidal zone. The high density polyethylene (HDPE) ducts will be installed using directional drilling.

6.2.3 Directional drilling typically progresses at a rate of several metres per hour. It is estimated that the finalisation of the ducts that form the cable landfall protection system will take 9−14 days, based on ten hour working days.

6.2.4 The installation of the export cables is likely to be carried out as follows:

o The cables will be pulled out towards the shore from a vessel positioned just offshore;

o The cable will be pulled onto the beach;

o Where the cable ducts are installed, the cables will be manoeuvred to the duct bell-mouth, cables attached to the draw wire in the duct and the cables winched through the duct and anchored in the onshore joint transition pit;

o The landing and pulling of each cable will take approximately 1 day; and

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o When the cable has been anchored in the transition pit the cable laying vessel will then proceed to lay it in an offshore direction towards the wind farm site for pulling in and termination in one of the wind turbines.

6.2.5 The offshore cable(s) will be buried and protected as appropriate in order to:

o Prevent movement of the cables over the life of the wind farm;

o Protect the cables from other activities such as fishing or the dragging of anchors; and

o Protect against the additional small risk posed from dropped objects.

6.2.6 Outside of the inter-tidal area the offshore cables will be buried using an underwater cable plough or trenching tool, such as water jetting unit, to a maximum depth of 1.5m below the seabed surface. The final target burial depth will be determined based on specific ground conditions as part of the final engineering design work.

6.2.7 The use of a cable plough results in the immediate installation and burial of the cable and seeks to ensure the minimum disturbance to the seabed. Total width of the area disturbed by plough installation is typically 0.5 to 1.0m. Further detail on these works is provided in sections 5.18 to 5.20 of the Project Design Statement (Document 7.2).

6.3 Vattenfall Offshore Cable Crossings

6.3.1 The Kentish Flats Extension export cables will cross the electricity export cables from the London Array Offshore Wind Farm approximately five kilometres from shore as shown on the Indicative Cable Crossing Plan (Document 2.5).

6.3.2 A pre-survey will be carried out using cable tracking device or similar. The survey area will be at least 50m both sides of the cable crossing over the existing cable to ensure location and heading.

6.3.3 Marker buoys will be used at the ‘As Found’ location of the cable. The location will also be highlighted within the navigation systems.

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6.3.4 To help maintain a positive separation between cables before laying the new cable concrete mattresses may be installed over the installed cables up to 20m either side.

6.3.5 A more detailed technical specification will be prepared as part of the legal agreement between Vattenfall and London Array Ltd. This specification will contain details of any anchor exclusion zones together with a technical specification for the crossing detail. The technical specification will include as a minimum, stability calculations to show that any cable covering material (such as mattresses or rock dumping) used at the crossing point will maintain its integrity for the anticipated lifetime of both the London Array and Kentish Flats Extension projects. Further details on the cable crossing works are provided in section 5.20 of the Project Design Statement (Document 7.2).

6.4 Vattenfall Onshore Works

6.4.1 The offshore cables will be jointed to onshore cables in a cable transition pit within the Hampton Pier car park.

6.4.2 The transition pit is typically built underground but close to the surface (see Document Number 2.3, Indicative Transition Pit Details). The construction of the transition pit is likely to be as follows:

o First is the tarmac surface broken up;

o A pit is then excavated, levelled and secured; and

o Once the pit is excavated, the supporting structure is built. This structure is likely to be comprised of a timber frame and a concrete plinth which constitutes the pit floor.

6.4.3 During the period of the construction works access to members of the public will be prevented and the area fenced and likely guarded. Further detail on the transition pit works is at section 6.2 of the Project Design Statement (Document 7.2).

6.4.4 The onshore export cables will be buried and installed in a similar manner to the existing cables already in-situ for Kentish Flats, with burial below the road surface with subsequent full-reinstatement.

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6.4.5 The cables will be installed directly in the ground at the bottom of a trench. The trench is likely to be about 1.2m deep and 0.5m wide. Fibre optics will have to be laid adjacent and parallel to the cables.

6.4.6 The trench will be backfilled using excavated materials and/or lean-mix cement, and there will be permanent reinstatement of roads and footpaths where affected by excavations. Further detail on the onshore cable works are set out in section 6.3 of the Project Design Statement.

6.4.7 Excavations to lay the 33kV on shore cables involve techniques in cable location, identification and avoidance. Excavation of trenches for ducts or direct buried cables will be carried out by hand in the vicinity of existing cables and other services. Mechanical excavators or powered hand tools will only be used to break surfaces or in areas where it has been confirmed that no other services are present.

6.4.8 In order to carry out excavation works persons need to: (i) have undergone excavations training, (ii) have been trained and know how to use excavation equipment, (iii) have appropriate certificates, (iv) hold a certificate for use with specialised equipment, and (v) have received training in reading cable plans and approved Codes of Practice for excavations.

6.5 Onshore Cable Duct Specification and Installation

6.5.1 If needed cable ducts will be installed in accordance to the Electricity Association Technical Specification 12-24 – Plastic Ducts for Buried Electric Cables.

6.5.2 Where cable ducts are installed in a common service trench with other services, a minimum distance of 200mm will be maintained between the cable duct and any water pipe and 100mm to any other service.

6.6 UKPN works

6.6.1 The design and installation methodology of the UKPN works at the Red House substation will be developed in due course by UKPN as appropriate.

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6.7 Status of Grid Connection

6.7.1 Vattenfall has held discussions with UKPN regarding the grid connection for the Kentish Flats Extension.

6.7.2 A feasibility study was undertaken by UKPN on behalf of Vattenfall during 2011 to investigate the availability of connection options within UKPN’s network. The feasibility study showed several possible options to connect to the Red House substation. The preferred option is described in paragraphs 3.3.6 – 7.

6.7.3 Vattenfall submitted an application to UKPN on 18 August 2011 for a connection for the Kentish Flats Extension to the Red House substation. This application requests both a full works offer (where UKPN will be responsible for designing and installing the onshore cable from the transition pit as well as their substation connection works) and a non-contestable offer (where Vattenfall will be responsible for the onshore cable works). It is expected that a grid connection offer will be received in November and Vattenfall will keep the IPC updated on progress with this, and the planning application for the onshore grid works, during the examination of the Kentish Flats Extension DCO.