RWE npower renewables’ North Hoyle Offshore Wind Fa … · TRITON KNOLL OFFSHORE WIND FARM...

TRITON KNOLL OFFSHORE WIND FARM

Environmental Statement

Volume 2: Chapter 12 – Other Marine Users

January 2012 Revision A

Document reference: 05/01/02/12

Pursuant to: Reg 5(2)(a)

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Triton Knoll Offshore Wind Farm Ltd Environmental Statement

Volume 2 – Chapter 12 RWE Npower Renewables Ltd


Triton Knoll Offshore Wind Farm

Environmental Statement

Volume 2: Chapter 12 – Other Marine Users

Document reference: 05/01/02/12

Pursuant to: Reg 5(2)(a)

January 2012

Revision A

Status: Final

Drafted By: RWE Npower Renewables Ltd

Approved By: Trevor Baker, RWE Npower Renewables Ltd

Date/ initial approval: 20th January 2012, TB.


RWE npower renewables

Auckland House

Lydiard Fields

Great Western Way

Swindon

Wiltshire, SN5 8ZT

Tel: 01793 474100

Email: [email protected]


Volume 2 – Chapter 12 RWE Npower Renewables Ltd

12 Other marine users 12.1

Introduction 12.1

Consultation and scoping 12.1

Methodology 12.2

Assessment criteria and assignment of significance 12.2

Baseline environment 12.3

Key parameters for assessment 12.8

Environmental assessment: construction and decommissioning phases 12.10

Environmental assessment: operational phase 12.11

Environmental assessment: cumulative effects 12.12

Conclusions 12.13

Transboundary effects statement 12.13

Summary 12.13


Volume 2 – Chapter 12 12.1 RWE Npower Renewables Ltd

12 Other marine users

Introduction

12.1 This chapter of the Environmental Statement (ES) considers the likely impacts of the proposed Triton Knoll Offshore Wind Farm (TKOWF) on other users of the marine environment, excluding commercial shipping and fishing. Throughout this chapter 'other marine users' is used as a specific term to include the following types of activity:

i) Renewable energy developments;

ii) Oil and gas developments;

iii) Cables and pipelines;

iv) Marine aggregate extraction; and

v) Telecommunications.

12.2 The potential impacts on recreational sailing and angling activities during the construction, operational and decommissioning phases of the TKOWF have been assessed in detail in Volume 2: Chapter 14 (Socio-economic assessment). The impacts on shipping and safety of navigation are considered in Volume 2: Chapter 10 (Shipping and navigation assessment). Impacts on commercial fishing are set out in Volume 2: Chapter 8.

Consultation and scoping

12.3 As part of the EIA process for the TKOWF, a scoping report was submitted to the IPC detailing the proposed approach to assessing the environmental impacts of the project (see Volume 3: Annex A). A formal scoping opinion was received from the IPC in September 2010 (see Volume 3: Annex B), which was used to inform the scope and content of the EIA process. Consultation relating to other marine users was carried out with a number of key organisations and stakeholders as part of the EIA process. This process was both informal and formal, the latter under S42 and S47 of the Planning Act 2008. A summary of the key issues raised by those consultees is presented in Table 12.1.

Table 12.1 Summary of key issues from consultation in relation to other marine users

Consultee, document and date

Consultation summarised comment Section where comment addressed

BP

meetings held on 29 June 2009, 15 September 2010 and 2 March 2011

Letter received on 12 July 2011

Radar: Impact to BP’s early warning radar system.

Seismic survey: impacts on safe conduct of seismic surveys and performance of data acquisition equipment.

Helicopter access: impact on instrument helicopter access, especially to B1D

See Volume 2: Chapter 10 for navigational impacts

Environmental assessment: Construction; paragraphs 12.23 - 12.34; Operational phase: paragraphs 12.43 - 12.47

See Volume 2: Chapter 13 for impact on helicopter

platform; potential impact on BP’s business.

access.

Conoco Phillips

meetings held 12 August 2008, 16 June 2009, 15 September 2009 and 3 March 2011

Pipelines: Potential crossings on pipelines running through the TKOWF project area by inter-array and inter-substation cables; proximity of turbines to the pipeline; potential risk of damage during construction.

Navigation: Potential impact upon pipeline maintenance and supply vessels.

Helicopter operations: Impact to ATC radars and helicopter operations.

Environmental assessment: Construction and decommissioning phases: paragraphs 12.35 - 12.38

See Volume 2: Chapter 10 for navigational impacts

See Volume 2: Chapter 13 for radar and helicopter interactions

Perenco UK

meetings held on 7 July 2009 and 17 September 2010

Letter received on 8

July 2011

Pipelines: Potential crossings on pipelines running through the TKOWF project area by inter-array and inter-substation cables; proximity of turbines to the pipeline; potential risk of damage during construction.

Microwave communication links: Conflict with two microwave links going through the OWF site from Pickerill A and B platforms to Sutton-on-Sea tower.

Helicopter operations: Impact on helicopter buffer on Pickerill A and B. Assessment and consultations have concluded the impact is negligible.



See Volume 2: Chapter 13 for radar and helicopter interactions

Shell UK Exploration and Production

correspondence dated 25/06/2009 and 16/07/2009

Telecommunications links: Potential conflict with offshore radio links that cross the TKOWF project area. Shell subsequently confirmed the TKOWF development will not affect these links.

No further assessment required

Westminster Dredging Ltd

Meetings held 7 May 2007, 12 December 2008, 22 February 2010, 19 January 2011 and 5th April 2011

Aggregate dredging operations:

The potential effect of the turbines on dredging vessels turning circles.

Impact on transit to/from the aggregate areas.

Displacement of fishing activity into Aggregates area 440

Inter-related impacts with other environmental aspects (e.g. physical processes).

Safety of dredging vessels in event of loss of power and drifting towards the wind farm

Environmental assessment: paragraphs 12.39 and 12.48 - 12.50

See Volume 2: Chapter 10 for navigational issues

No further assessment required

See Volume 2: Chapter 8 for issues relating to fishing

Volume 2: Chapter 15: inter-related impacts and Volume 2: Chapter 2 cumulative effects on physical processes



Methodology

12.4 The assessment considered the potential interaction of the TKOWF as described by the project details set out in Volume 1: Chapter 6 and contained within the boundary area of the site presented in Figure 12.1, on the current operations and existing features in the marine environment. The scope of the assessment has been defined through a process of consultation with the operators of existing marine infrastructure.

12.5 Identification of other marine users was initially made through a desktop review of GIS datasets through the earliest constraints mapping process in order to identify features and operators and buffers that may be potentially affected by the TKOWF project. The features identified and the datasets used were:

i) UK Hydrographic Office (UKHO);

ii) The Crown Estate ( for offshore wind farm data);

iii) UK Digital Energy Atlas Library (UKDEAL); and

iv) Telecommunications operator’s data.

12.6 Stakeholder consultation enabled the scope of the ensuing impact assessments to be defined and informed the evolution of the boundary of the wind farm site.

12.7 Additional work has been undertaken following consultation to assess potential effects on telecommunication links (undertaken by Sutton Electronics on behalf of RWE and Perenco UK Ltd). The study was carried out in two phases: the first phase was to identify feasible options; the second phase was a detailed feasibility and costing study on the preferred option(s) to inform a commercial agreement between TKOWFL and Perenco UK Ltd. The results of this study have been used to inform this ES and can be found in Volume 3: Annex M.

12.8 In addition, further work was carried out into the risk of collision with turbines and other structures from possible drifting of dredgers operating in the adjacent licensed aggregate Area 440. The results of the study are contained in Volume 3: Annex K, and will form the basis of an agreement between TKOWFL and the dredging operators.

Assessment criteria and assignment of significance

12.9 The impact assessment for other marine users has been carried out in accordance with the approach described in Volume 1: Chapter 5, drawn from the requirements of the Infrastructure Planning (EIA) Regulations 2009.

12.10 The sensitivities of marine infrastructure and operational features were defined by both their potential vulnerability to an impact from the wind farm and their recoverability. Magnitude was defined by a series of factors including a consideration of the maintenance of separation distance as defined through consultation, the spatial extent of any potential interaction, the likelihood, duration and frequency of a potential impact.

12.11 Definitions of significance were rated between low where no impact is foreseen, to high where interaction between the TKOWF and the other marine users may occur. The combination of sensitivity of receptor and magnitude has been used to define a level of significance through the use of a matrix approach as presented in Volume 1: Chapter 5.

12.12 The scope of this assessment included the issues listed in Table 12.2, identified through desk based assessment and consultation.

Table 12.2 Key issues for assessment

Assessed issues

Renewable energy developments

Vessel operation interaction during maintenance operations at other wind farm sites (assessed in Volume 2: Chapter 10)

Impacts on oil and gas support services during construction, operation and decommissioning

Oil and gas developments

Buffers between TKOWF and oil and gas infrastructure during construction, operation and decommissioning

Gas pipelines Buffers and crossings at gas pipelines where inter-array cables cross during construction, operation and decommissioning

Marine aggregate extraction Safety and commercial viability of dredging vessel operations during construction, operation and decommissioning

Telecommunications Interference with telecommunications links during operation

12.13 In addition, guidance provided within the National Policy Statement for Renewable Energy Infrastructure (EN-3; DECC, 2011) with regard to oil and gas and other offshore infrastructure and activities was considered in undertaking the assessment on other marine users. NPS EN-3 (para 2.6.179 – 2.6.181) includes guidance on what matters are to be included in an applicant’s assessment of potential impacts to other marine users and are summarised below in Table 12.3.

Table 12.3 Summary of NPS EN-3 guidance of assessment on other marine users and consideration in the TKOWF assessment

Summary of NPS EN-3 guidance on assessment of other marine users

TKOWF assessment

Applicants should undertake an assessment of the potential effect of the proposed development on existing or permitted offshore infrastructure or activities and for all stages of the development

Applicants should engage with interested parties in the potentially affected offshore sectors early in the development phase with an aim to resolve as many issues as possible prior to the submission of an application to the IPC. Such engagement should continue throughout the life of the development where necessary. Such engagement should be taken to ensure that solutions are sought that allow offshore wind farms and other uses of the sea to successfully co-exist.

The TKOWF assessment has considered the potential effects and provided an assessment of their likely significance, considering each phase of the development process (i.e. construction, operation and decommissioning), based in large part on the results of extensive consultation with the relevant interests. Engagement will continue between TKOWFL and other marine users to refine solutions as projects progress,

12.14 NPS EN-3 (para 2.6.182 – 2.6.188) also contains guidance on those things the IPC should consider in its decision making and on mitigation. A summary of this guidance is provided in Table 12.4.



Table 12.4 Summary of NPS EN-3 guidance on the IPC’s decision making with regard to other marine users and consideration in the TKOWF assessment

Summary of NPS EN-3 guidance on IPC assessment TKOWF assessment

There are statutory requirements on the establishment of navigational safety zones relating to offshore petroleum developments.

A 500 m buffer area around the gas platforms and pipelines has been designed into the TKOWF.

Where a wind farm potentially affects other infrastructure or activity, a pragmatic approach should be employed by the IPC. The IPC should expect the applicant to minimise negative impacts and reduce risks to as low as reasonably practicable (ALARP).

Advice on the activities of other marine industries is being sought to avoid or reduce the effect through mutually agreed solutions.

The IPC should be satisfied that the site selection and site design of the wind farm has avoided or minimised adverse effects on other offshore industries. The IPC should not consent applications which pose unacceptable risks to safety after mitigation measures have been considered.

Where a proposed development is likely to affect the future viability or safety of an existing or approved/ licensed offshore infrastructure or activity, the IPC should give these adverse effects substantial weight in its decision-making.

Where schemes have been carefully designed and the necessary consultation has been undertaken at an early stage, mitigation measures may be found that can negate or reduce effects on other offshore infrastructure or operations to a level sufficient to enable the IPC to grant consent.

In relation to mitigation: Detailed discussions between the applicant and the relevant consultees should have progressed as far as reasonably possible prior to the submission of an application. As such, appropriate mitigation should be included in any application and ideally agreed between relevant parties. In some circumstances, the IPC may wish to consider the potential to use requirements involving arbitration as a means of resolving how adverse impacts on other commercial activities will be addressed.

TKOWF has been sited to minimise conflicts with other users. Where such conflicts remain they are being addressed through discussion with the other operators to ensure adequate mitigation and safe working.

Summary of data sources used in assessment

Baseline environment

12.15 The baseline environment for other marine users and activities in the TKOWF area is summarised within Table 12.5 and also shown in Figure 12.1, with the operations and infrastructure closest to TKOWF shown in more detail in Figure 12.2.

Data limitations

12.16 Charts are prepared to inform the impact assessment only and are prepared with the best available data at the time.



Table 12.5 Summary of other marine users relevant to the TKOWF project

Activity Project details Developer Status Distance (km) from TKOWF site (Order Limits)

Predicted construction period

Lynn Centrica Operational 40.5 Operational

Inner Dowsing Centrica Operational 35.0 Operational

Lincs Offshore Centrica Construction phase 25.7 2011-2012

Sheringham Shoal Statoil Hydro Construction phase 26.4 2011-2012

Dudgeon (formerly 'Dudgeon East') Warwick Energy Offshore consent granted; onshore consent in determination

26.7 2013-2015

Humber Gateway E.ON UK Renewables Consented 28.9 2012-2013

Race Bank Centrica Determination 11.0 2013-2014

Docking Shoal Centrica Determination 31.5 2015-2016

Hornsea Zone Round 3 OWF (Project 1) SMartwind Pre-application 33.0 2014-2017

Offshore wind farms

Westermost Rough DONG Consented 45.0 2012-2014

Area 440 Westminster Dredging Ltd Operational 0.0 N/A

Area 441 (1) Westminster Dredging Ltd Operational 5.6 N/A

Area 441 (2) Westminster Dredging Ltd Operational 9.1 N/A

Area 105 Cemex UK Marine Operational 4.3 N/A



Area 106 (a) Hanson Aggregates Marine Ltd Operational 9.8 N/A

Area 106 (b) Hanson Aggregates Marine Ltd Operational 7.7 N/A

Area 106 (c) Hanson Aggregates Marine Ltd Operational 10.2 N/A


Area 197 United Marine Dredging Operational 16.2 N/A

Area 408 (Coal Pit/Sole Pit) Hanson Aggregates Marine Ltd Operational 48.0 N/A

Area 481 (1) Tarmac Marine Dredging Ltd Operational 18.3 N/A

Marine aggregate extraction

Area 481 (2) Van Oord Ltd Operational 20.5 N/A

PL816/PL817: Pickerill to Theddlethorpe 24 inch gas pipeline and 3 inch methanol pipeline

Perenco UK Ltd Live 0.5 N/A Subsea pipelines

PL929: Theddlethorpe to Murdoch MD 26 inch gas pipeline and 4 inch methanol line

Conoco Phillips Live 0.5 N/A

Block 47/15a (Amethyst field) BP Exploration Operating Company Limited

In exploitation -0.5 (maximum overlap of 500m within block 47/15a)

N/A Oil and gas

Block 47/14b GDF Suez E&P UK Ltd In exploration 0 N/A



Activity Project details Developer Status Distance (km) from TKOWF site (Order Limits)

Predicted construction period

Blocks 47/14c (exploration licence) GDF Suez E&P UK Ltd Licence to explore blocks awarded in September 2010

-6.3 (maximum overlap of 6.3 km)

N/A

Block 47/19a Bridge Resources E&P Ltd Relinquished in December 2010 -4.8 (maximum overlap of 4.8 km)

N/A

Amethyst B1D (normally unmanned installation (NUI))

BP Exploration Operating Company Limited

Operating 2.8 N/A

Amethyst A2D (NUI) BP Exploration Operating Company Limited

Operating 9.8 N/A

Amethyst A1D(NUI) BP Exploration Operating Company Limited

Operating 9.3 N/A

Amethyst C1D (NUI) BP Exploration Operating Company Limited

Operating 15.0 N/A

Pickerill A (NUI) Perenco UK Ltd Operating 12.6 N/A

Pickerill B (NUI) Perenco UK Ltd Operating 15.9 N/A

Guinevere Perenco UK Ltd Operating 18.3 N/A

Juliet well GDF Suez E&P UK Ltd Under development 2.2 2012

Pickerill A to Sutton-on-Sea Tower Perenco UK Ltd Operational 0 N/A

Pickerill B to Sutton-on-Sea Tower Perenco UK Ltd Operational 0 N/A

Location A (Carrack North) Shell UK Exploration & Production Ltd

Operational - main 0 N/A Telecommunications

Location B (Cutter QC) Shell UK Exploration & Production Ltd

Operational - diversity 0 N/A



Figure 12.1 TKOWF project area, regional location and other marine users



Figure 12.2 Marine users in close proximity to the TKOWF



Key parameters for assessment

12.17 The TKOWF project infrastructure is described in Volume 1: Chapter 6 of this ES. As discussed in Volume 2: Chapter 7, a maximum development envelope based on the Rochdale envelope principle has been developed for the project EIA. Table 12.6 describes the Rochdale envelope scenario for each potential effect on other marine users upon which the EIA has been based.

12.18 The assessment of the maximum adverse scenario for each receptor establishes the maximum potential adverse impact as a result. TKOWFL is, therefore, confident that impacts of greater adverse significance would not arise should any other development scenario (as described in Volume 1: Chapter 6) to that assessed within this chapter be taken forward in the final scheme design. For instance, subsequent to this assessment the maximum number of turbines has been reduced from 333 to 288, and thus the maximum adverse scenario has been assessed.

12.19 It is noted that only those design parameters detailed under each specific impact in Table 12.6 have the potential to influence the significance of the impact described. Therefore, if a particular design parameter is not discussed then it is considered not to have a material bearing on the outcome of the assessment.

12.20 The maximum adverse effects scenarios set out in Table 12.6 consider both direct and indirect impacts as required. Cumulative impacts scenarios are also described.

Table 12.6 Rochdale envelope scenario assessed

Potential effect Maximum adverse

scenario Justification

Construction / decommissioning:

Physical obstruction - turbines creating permanent obstacles for helicopter approaches to, and departures from, gas platforms, especially for instrument approaches, leading to potential impact on gas production and business revenues.

Within the TKOWF site (Order Limits) and for the life of the project, placement of the following structures:

150 x 8 MW class turbines with a tip height of up to 220 m, hub height up to 140 m and rotor diameter of up to 180 m

4 meteorological monitoring masts of up to 200 m height (Above LAT)

Up to 8 offshore substations up to 100 m height (above LAT)

The largest turbines placed within the TKOWF area provides the maximum adverse case as instrument approaches have to start 1000 ft above any vertical obstacle. Depending on wind direction, the presence of the turbines could make the descent gradient too steep to approach the platform into the wind. Maximum heights of met masts and substation platforms provide the greatest potential for these to have an effect on helicopter approaches.

Any of the other development scenarios considered within Volume 1: Chapter 6 would result in no greater or less of an effect on helicopter approaches.



Temporary disturbance during construction and decommissioning phases to dredging vessels transiting to/from extraction sites through TKOWF project area.

Complete exclusion from the TKOWF site (Order Limits) and during 5 years of construction.

Maximum number of construction vessel movements estimated to be circa 7,700 per year.

It is assumed that all vessels, including dredging vessels, will avoid the entire area during construction thereby giving rise to the greatest potential effect on their operations. The greatest number of construction vessel movements similarly gives rise to the greatest potential for effects on dredger operations and safety.

Any of the other development scenarios or installation techniques considered within Volume 1: Chapter 6 would result in no greater or less vessel movements and corresponding effects on dredging vessels.

Temporary disturbance to existing pipelines during construction

Within the TKOWF site (Order Limits) and during 5 years of construction, installation of:

Up to 333 x 3.6 MW class turbines

Up to 475 km of associated inter-array and inter-substation cabling with cable crossings

Maximum number of construction vessel movements estimated to be circa 7,700 per year.

The greatest number of turbines gives rise to the greatest length of installed cables and associated pipeline cable crossings, thereby providing the greatest potential for impacts on the pipelines. This scenario also gives rise to the greatest number of construction vessel movements with attendant risks to the pipelines from anchoring, jack up vessels etc.

Any of the other development scenarios or installation techniques considered within Volume 1: Chapter 6 would result in no greater or less cable crossings and vessel movements and corresponding effects on pipeline integrity.

Operation:

Physical obstruction - turbines creating permanent obstacles for helicopter approaches to, and departures from, gas platforms, especially for instrument approaches, leading to potential impact on gas production

Within the TKOWF site (Order Limits) and for the life of the project, placement of the following structures:

150 x 8 MW class turbines with a tip height of up to 220 m, hub height up to 140 m and rotor diameter of up to 180 m

4 meteorological monitoring masts of up to 200 m height (Above LAT)

The largest turbines placed within the TKOWF area provides the maximum adverse case as instrument approaches have to start 1000 ft above any vertical obstacle. Depending on wind direction, the presence of the turbines could make the descent gradient too steep to approach the platform into the wind. Maximum heights of met masts and substation platforms provide the greatest potential for these to have an effect on helicopter approaches.

Any of the other development scenarios considered within Volume 1: Chapter 6 would result in no greater or less of an effect on helicopter approaches.





and business revenues.

Up to 8 offshore substations up to 100 m height (Above LAT)

Physical disturbance to seismic surveys associated with oil and gas operations during wind farm operations

Within the TKOWF site (Order Limits) and for the life of the project, installation of:


Up to 4 meteorological monitoring masts;

Up to 8 offshore substations

The greatest number of turbines results in the smallest turbine spacing and therefore the greatest potential constraint on seismic survey operations (along with the greatest number of met masts and substations).

Any of the other development scenarios considered within Volume 1: Chapter 6 would result in no greater or less effects on O&G seismic operations within the TKOWF site.

Physical presence - turbines creating permanent obstacle to dredging vessels transiting through TKOWF project area to/from extraction sites.



Up to 4 meteorological monitoring masts;

Up to 8 offshore substations

The greatest number of turbines results in the smallest turbine spacing and therefore the greatest potential constraint on the navigation of dredging vessels through the wind farm (along with the greatest number of met masts and substations).

Any of the other development scenarios considered within Volume 1: Chapter 6 would result in no greater or less effects on dredging vessel navigation within the TKOWF site.

Physical presence - wind farm structures creating permanent obstacle to dredging vessels turning circles for those operating in Area 440 adjacent to the TKOWF site boundary.

The installation of any wind farm structures within the TKOWF site (Order Limits) and for the life of the project, along the boundary with Area 440.

The presence of any offshore wind farm structure (turbine, met mast or substation) along the southern boundary gives rise to a risk of collision and therefore may impact upon the operation of that dredging vessel.

Physical presence - turbines creating interference for

Telecommunicati-on links through the TKOWF


Up to 333 x 3.6 MW turbines; up to 75 m hub height, 160 m tip height

The greatest number of turbines (and met masts and substations) located within the wind farm area provides for the greatest blocking potential to line of sight telecommunications links between offshore platforms and the coast.

Any of the other development scenarios considered within Volume 1: Chapter 6 would



project area between oil and gas platforms and the mainland.

and 125 m rotor diameter.

Up to 4 meteorological monitoring masts (Up to 200 m height)

Up to 8 offshore substations (Up to 100 m height

result in no greater or less effects on telecommunications links.

Cumulative:

Additional vessel traffic during construction, operation and decommissioning with all existing and planned activities

TKOWF scenario as described above for construction vessels; for operations, estimated vessel movements circa 18,440 per annum (mostly within the TKOWF area).

Cumulative impacts with vessels/ activities laying the TKOWF export cables, at R1, R2 and R3 OWFs, marine aggregate extraction areas, oil and gas exploration and production facilities (platforms, wells)

The TKOWF scenarios provide for the greatest estimated number of vessel movements and thereby provides the maximum adverse case for the cumulative assessment.

Specific details and assumptions applied for the other activities are set out in the assessment text and also by reference to the Shipping and Navigation Assessment (Volume 2: Chapter 10).

12.21 The project design envelope was established with a maximum number of turbines and associated foundations of ‘up to 333’ which has been used where appropriate as the basis for the ‘maximum adverse scenario’ in the impact assessment. Subsequently, and in response to the assessment of impacts on birds (see Volume 2: Chapter 6), the maximum turbine number has been reduced to ‘up to 288’ – the number set out in Schedule 1 of the draft DCO (application document reference 03/01). The basis of the assessment using the maximum of 333 turbines has been subsequently reviewed and an assessment based on the 288 turbine layout would be no greater than, and probably less than, the scenario assessed in the EIA.



Environmental assessment: construction and decommissioning phases

12.22 The potential effects on other marine users during the construction and/or decommissioning phase of the TKOWF project are discussed below.

Physical presence – interaction with oil and gas activities

12.23 The TKOWF site overlaps BP’s licensed block 47/15a, by up to approximately 500 m in the northern corner of the site. Although there is no current structure on that part of the block, BP raised concerns about the impact on their ability to undertake seismic surveys. BP conducts seismic surveys using air guns which emit pressure waves that are reflected by subsurface ground layers and detected by seismic detectors. Seismic surveys are typically carried out by a vessel towing the detectors through the water, necessitating approximately 10 km of open sea around the area being surveyed to secure complete coverage from all the recording cables and ensure that the boat and cables can be turned at the end of each set of measurements (BP consultations minutes, 15/09/2010). These turning circles would not be possible once the wind farm is constructed if BP wants to survey that part of the block. However, consultation with BP has identified a potential for seismic surveys to be undertaken before construction of the TKOWF depending on the construction programme.

12.24 The closest operational offshore installation to the TKOWF is Amethyst B1D, lying 2.8 km (1.5 nm) to the north and within BP’s licence block 47/15a (Amethyst East Field). Possible impacts on this platform include possible effects on helicopter operations to/from the platform (the assessment of this impact on flight operations is discussed in Volume 2: Chapter 13; paragraphs 13.35 to 13.52), and impacts upon passing shipping traffic (assessment discussed in Volume 2: Chapter 10; paragraph 10.96). Impacts on the other platforms in the wider area are also discussed in these chapters and are assessed as being of negligible significance.

12.25 BP was concerned that even a small reduction of platform access probability could have an impact on their business. The B1D platform is a Normally Unmanned Installation (NUI), which requires helicopter access for planned maintenance campaigns and emergency repairs. Therefore the potential impact of TKOWF depends on weather conditions and wind direction during these campaigns and when failures happen. Although the percentage of precluded flights to B1D might be negligible averaged on a whole year, it might become significant if it happens during the maintenance campaign (planned or unplanned). However the likelihood of this happening is very small. The impact on BP’s business is therefore difficult to predict and BP has not been able to determine the extent of the potential impact on their business.

12.26 BP announced in 2011 that they would sell their Amethyst assets. The process is yet to be concluded. Any ongoing discussion with BP about interaction with TKOWF will be continued with the new owner.

12.27 The TKOWF project area also overlaps three oil and gas blocks licensed by GDF Suez: (47/14b and 47/14c) and one block licensed by Bridge Resources (47/19a) (Figure 12.1). Consultation with Bridge Resources has identified that they have relinquished block 47/19a and other blocks around it in December 2010. There are no installations on these blocks. Consultations with GDF Suez have identified the development of a subsea well on the Juliet field in the 47/14b block, to the north of TKOWF (Figure 12.2). GDF Suez has confirmed that there are not likely to be any significant effects to their activities

regarding the Juliet development as the infrastructure will be subsea. The latest consultation with GDF Suez in September 2011 showed GDF’s intention to tie back the Juliet well to the Pickerill A platform, instead of Amethyst A2D as previously envisaged, with a pipeline running to the North of the TKOWF site taking its boundary into account. However GDF does not preclude any future interaction on the rest of the blocks during seismic surveys and potential future gas finds.

12.28 A number of other wells exist within 3 km of the TKOWF site, the closest being located to the east of the TKOWF site (Figure 12.2). These wells are either suspended or plugged and abandoned.

Mitigation measures

12.29 TKOWFL envisage close cooperation with BP to plan the timing of construction activities to minimise the impact on BP’s seismic surveys where possible. BP’s seismic surveys will be factored into the site construction sequence and, if possible, early construction activities will be started away from the BP licensed block.

12.30 Mitigation measures for helicopter access to Amethyst B1D are discussed in Volume 2: Chapter 13. TKOWFL will follow BP’s requirement stated in their letter on 12th July 2011: “If the affect on Amethyst B1D is sufficiently material to have a business impact then BP will seek the implementation of mitigation measures to reduce this impact.” Communication will be maintained between TKOWFL and BP (or its successor) and its helicopter operators during the lifetime of the project to address potential significant impact on their business.

12.31 A study on potential impact on navigation radar systems has been undertaken by QinetiQ (contained in Volume 3: Annex K) and the navigation assessment has concluded that there would not be any adverse effect on BP’s early warning system (assessment discussed in Volume 2: Chapter 10; paragraphs 10.165 to 10.169). The study looked at the effects of the early warning radars located on the Cleeton Ravensburn B, A1D and West Sole Alpha platforms. Whilst the study indicated that there may be some effect, i.e. false plots in the area between the A1D platform and the wind farm, it was considered that because this radar forms one of four inputs into a composite radar picture the false plots would be detected and eliminated by the radar operator. However, BP had concerns that the composite picture might be affected and required the QinetiQ report to be passed to their radar operator Ultra Electronic CCS for their technical assessment. TKOWFL has not, as yet, been provided by BP with the review of this study that has been completed by Ultra Electronics CCS. From communication with BP it is understood that BP was unavailable to complete the review because of the commitments required in the sale process of the assets. Therefore it is not known whether the composite picture of the Radar Early Warning System operated by Ultra Electronics will be affected by the offshore wind farm. If this is identified as a potential impact, the following mitigation measures could be applied:

i) TKOWF is already proposing a vessel monitoring system as a safety control for navigation and collision prevention. This system could potentially be extended to BP platforms as a complement to the radar system. A cooperation and communication system between the two parties would be agreed; and

ii) The other possibility would be the installation of an additional radar system to supplement the existing system to overcome potential significant deficiencies caused by the presence of the wind farm.



12.32 TKOWFL will continue to work with BP and the new asset owner to resolve this issue. In the event of the Ultra Electronics report identifying a potential impact on BP’s radar system, both parties will agree whether an additional study is required to identify appropriate mitigation.

12.33 Discussion and communication will be on-going with GDF Suez or any successive operators of the blocks on and around the TKOWF site during the lifetime of the project. Mitigation measures, compromises and synergies will be sought wherever possible in order to accommodate continued exploitation of both resources.

Likely environmental effects

12.34 Where suitable mitigation and operating procedures are agreed there will be no significant effect on existing or proposed oil and gas operations.

Potential impacts on existing pipelines

12.35 There are two pipelines that bisect the TKOWF site (see Figure 12.1): the Theddlethorpe to Murdoch pipeline and the Pickerill A to Theddlethorpe pipeline. Both are followed by methanol lines running parallel to them. A 500 m exclusion zone has been imposed to each side of the pipelines. Within this exclusion zone, no construction operations will occur with the exception of mutually agreed pipeline crossing operations.

12.36 The crossing of existing pipelines by the inter-array cabling is being discussed with the relevant pipeline operators. During consultations with the pipeline owners, TKOWFL has proposed to put in place agreements to govern the proposed crossings of inter-array cables and inter-platforms cables and the issue of turbine proximity to the pipelines. Such agreement has been progressed between Perenco and TKOWFL up to a point where both parties are satisfied with the terms and conditions. However the agreement remains unsigned. Negotiations are also on-going between Conoco-Phillips and TKOWFL. It has been agreed that more discussions will be needed once the wind farm and crossing designs are finalised. The final design of the crossings will be agreed between TKOWFL and the pipeline operators when more design details are available, including consideration of potential induced electromagnetic currents and associated effects. It is TKOWFL’s intention to continue these discussions with Perenco and Conoco-Phillips and complete the agreements before the start of construction.

Mitigation measures

12.37 Pipeline crossing and proximity agreements are being discussed with Conoco Phillips and Perenco and will be put in place prior to construction of the inter-array cabling across the existing pipelines and construction of the met mast/ turbines.


12.38 Where suitable mitigation and operating procedures are agreed there will be no significant effect on existing pipelines.

Temporary obstruction to transit routes used by marine aggregate dredging vessels

12.39 Marine aggregate extraction activities occur in the vicinity of the TKOWF site, with the closest consented extraction site (Area 440) lying directly adjacent to the TKOWF southern boundary (Figure 12.1). During construction, increased vessel traffic

associated with TKOWF may increase the risk of ship to ship collisions for aggregate dredgers in transit to east coast port facilities. The potential for this impact to arise has been assessed in detail in Volume 2: Chapter 10; paragraphs 10.158 to 10.163.

Mitigation measures

12.40 The need for mitigation measures in relation to potential effects on dredging vessels are set out in Volume 2: Chapter 1; paragraph 10.161.


12.41 Proposed mitigation measures will reduce the residual navigational risk to a tolerable level (see Volume 2: Chapter 10; pargraph 10.163).

Environmental assessment: operational phase

12.42 The potential effects to other marine users during the operational phase of the TKOWF are to oil and gas operations, marine aggregate dredging and telecommunications links. These are discussed below.

Physical presence – interaction with oil and gas operations

12.43 Interactions between oil and gas operations and the TKOWF include those with early warning radar system, helicopter support operations and seismic surveys. These potential effects during operational phase are similar to those described in paragraph 12.23 to 12.28 above.

12.44 Further discussion with BP identified the need for seismic surveys after the construction of TKOWF. BP also mentioned that an alternative survey method was available, which would not necessitate large turning circles and could potentially constitute a solution that would allow BP to carry out seismic surveys after installation of the TKOWF. This method uses Ocean Bottom Cables (OBC) with seismic detectors laid on the seabed, which can detect both pressure and shear waves. However, BP has expressed concerns that seismic vibrations produced by the turbines in operation could be detrimental to the data quality of the recording and can affect BP’s ability to produce accurate subsurface maps for gas field development.

12.45 As this issue was raised late in the consultation process, discussions and assessment are still on-going. The impact will depend on seismic frequencies and amplitudes produced by the turbines and those of interest to oil and gas field mapping.

Mitigation measures

12.46 TKOWF intends to continue working with BP to understand better the requirements of the OBC type of equipment and the potential impact of the seismic vibrations emitted by the turbines in operation in order to find potential mitigation measures.


12.47 Where suitable mitigation and operating procedures are agreed there will be no significant effect on oil and gas operations during the operational phase.



Obstacle to transit routes used by aggregate dredging vessels

12.48 The physical obstruction of the Triton Knoll wind turbine array could impede transiting dredging vessels to and/or from excavation sites passing through the wind farm area.

Mitigation measures

12.49 The extent of the impact and possible mitigation measures for the impacts to marine aggregate extraction due to possible diversions of dredging vessels around the TKOWF when transiting to and/or from extraction sites are discussed in detail in Volume 2: Chapter 10; paragraphs 10.97 to 10.107.


12.50 The effect of the proposed wind farm on the safe navigation of vessels engaged in marine aggregate dredging, once the mitigation control measures and operating agreement described in Volume 2: Chapter 10; paragraphs 10.161 to 10.107 are in place, would reduce the likelihood of any occurrence to very infrequent. The residual navigational risk was therefore concluded to be tolerable.

Impacts on dredging vessel activity in the adjacent dredging Area 440

12.51 During operation, the presence of the southern-most TKOWF turbines may create an obstacle for dredging vessels turning out of area in a northerly direction, which may occur outside of the licensed dredging area, the vessel at that time being limited in its ability to manoeuvre. The impact on dredging vessels (normal operations and drifting ships scenarios) has been considered in Volume 2: Chapter 10; paragraphs 10.161 to 10.163).

Mitigation measures

12.52 The shipping and navigation assessment, and discussions with the dredging company has identified that some form of mitigation would be required to ensure adequate separation between dredging activities and the closest wind turbines (both to mitigate against out of area turning and drifting ship scenarios). An agreement is being reached on these issues with the dredging company, taking into consideration vessel types, size, tide and weather conditions.


12.53 Where suitable mitigation and operating procedures are agreed there will be no significant effect on marine aggregate dredging operations during the operational phase.

Interference with telecommunication links

12.54 Two telecommunication links owned by Perenco will be affected by the TKOWF (Table 12.5). During operation, the turbines may affect line of sight transmission for these fixed communications links between the UK coast and Perenco’s platforms at Pickerill A and B.

Mitigation measures

12.55 A feasibility study investigated the available options to replace the existing microwave links (report by Sutton Electronics; see Volume 3: Annex M). The study looked at alternative technologies and alternative line of sight paths. The study was carried out in two phases: the first phase was to identify feasible options; the second phase was a detailed feasibility and costing study of the preferred option(s). The results of this study can be found in Volume 3: Annex M. In consultation with Perenco, three preferred solutions were identified at the end of phase 1. These are alternative paths for microwave line-of-sight technology, which is the technology currently used by Perenco. These paths use existing infrastructure in the southern North Sea, sometimes owned by third parties. The three options are summarised as follows:

i) Use of Amethyst platform (BP) and Dimlington tower

ii) Use of Waveney platform (Perenco) – Bodham tower (Norfolk Constabulary)

iii) Use of South Clipper platform (RWE Dea) – LOGG platform system (Conoco-Phillips) – 27A platform (Perenco)

12.56 Phase 2 of the feasibility study investigated in more detail the feasibility and cost of the potential options by contacting the third parties involved and identifying additional works and equipment. The study shows that viable solutions are available to mitigate the impact of the TKOWF. The study will be used as a basis to inform a commercial agreement between Perenco UK Ltd and TKOWFL, whereby TKOWFL agrees to fund the solution and any reasonable operational costs over and above costs currently incurred by Perenco for the operation of their communication links. The preferred option will be discussed with Perenco and will be reviewed again before construction of the TKOWF to ensure the best possible solution is in place at the time of construction to maintain the same capacity and reliability as the current links.


12.57 The feasibility study has demonstrated that solutions are available at reasonable cost for TKOWFL to provide Perenco with the best possible solution to maintain the same capacity and reliability as the current links. Therefore the environmental effect will be of negligible significance.

Environmental assessment: cumulative effects

12.58 Where the construction of one or more wind farm projects overlap, mitigation measures proposed for the safety of navigation and detailed in Volume 2: Chapter 10 will manage the wind farm traffic in order to minimise interactions during construction. Additional maintenance vessel traffic, and potential interactions with Westernmost Roughs, Humber Gateway or other wind farms in the Greater Wash, which may also use the Humber ports, would also be addressed through a traffic management system, effective traffic liaison and providing indications of and broadcast information about any potential vessel traffic problems in the project area and its proximity (see Volume 2: Chapter 10).

12.59 No cumulative impact will occur from TKOWF vessel traffic with oil and gas maintenance or support operations as any potential interaction of vessels will occur on only a temporary and intermittent basis and will be subject to appropriate vessel management and monitoring.



12.60 Cumulative impacts during construction, maintenance operations and decommissioning and effects on marine traffic related to marine aggregate extraction are discussed in more detail in Volume 2: Chapter 10.

12.61 There is no cumulative interaction between the TKOWF infrastructure and the existing telecommunications infrastructure.

Conclusions

12.62 For most activities and users of the TKOWF site the following mitigation measures will ensure that there are no significant impacts on other marine users:

i) Oil and gas activities - impacts to seismic surveys will be considered further during ongoing consultation to provide a suitable solution to ensure no significant effect. Helicopter operations to and from adjacent gas platforms in the southern North Sea are discussed in more detail in Volume 2: Chapter 13; TKOWFL will continue to work with the helicopter operators and BP or its successor to agree on mitigation in case of significant impact on BP’s business.

ii) Marine aggregate extraction - likely to be impacted by construction activity (safety zones, increased vessel traffic), and physical presence of the turbines during operation hampering transit through the TKOWF site and the safety of dredging vessels. These potential effects are discussed in more detail in Volume 2: Chapter 10 and will be subject to agreement with the dredging operators.

iii) Telecommunications – the oil and gas communication links were the subject of a detailed feasibility study concluding that viable solutions are available to replace these links, whilst maintaining the same capacity and reliability. A study of impact on BP’s early warning radar system within the QinetiQ study has concluded that there would be no significant impact after mitigation. However, BP still has concerns over the impact on the radar composite picture. The final assessment will depend on BP’s technical assessment. Other impacts on telecommunications (navigation radars, Automatic Identification System (AIS), etc.) are discussed in Volume 2: Chapter 10.

12.63 Commercial shipping, fishing and recreational sailing and angling are discussed in separate topic chapters in Volume 2: Chapters 10, 8 and 14, respectively.

Transboundary effects statement

12.64 There will be no significant effects on oil and gas nor marine aggregate dredging interests given the proposed mitigation and anticipated agreements set out in this chapter. Given this conclusion, and the fact that the TKOWF lies entirely in the UK REZ and at least 130 km from the nearest EEZ of another member state, there can be no significant transboundary effects in relation to other marine development activities.

Summary

12.65 The assessment on marine users in the vicinity of the proposed TKOWF development has concluded that there would be no significant effect on other marine users where the proposed mitigation measures are agreed and implemented. Further consultation and discussion will take place during the life time of the project and TKOWFL will continue to

work in cooperation with the other marine users and operators as the project progresses to ensure all projects are viable and safe to operate.

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