Triton Knoll Offshore Wind Farm Limited

TRITON KNOLL ELECTRICAL SYSTEM

Environmental Statement

Volume 2

Chapter 6: Marine Mammals

April 2015, Revision A

Document Reference: 6.2.2.6 Pursuant to: APFP Reg. 5(2)(a) Triton Knoll Offshore Wind Farm Ltd Triton Knoll Electrical System Environmental Statement - Volume 2

Copyright © 2015 Triton Knoll Offshore Wind Farm Limited All pre-existing rights reserved. Triton Knoll Offshore Wind Farm Limited

Triton Knoll Electrical System Liability In preparation of this document Triton Knoll Offshore Wind Farm Limited (TKOWFL), a joint venture between RWE Environmental Statement Innogy UK (RWE) and Statkraft UK, subconsultants working on behalf of TKOWFL, have made reasonable efforts to Volume 2: Chapter 6 – Marine Mammals ensure that the content is accurate, up to date and complete for the purpose for which it was prepared. Neither TKOWFL nor their subcontractors make any warranty as to the April 2015 accuracy or completeness of material supplied. Other than any liability on TKOWFL or their subcontractors detailed in the contracts between the parties for this work neither TKOWFL or their subcontractors shall have any liability for any loss, damage, injury, claim, expense, cost or other Drafted By: GoBe Consultants Ltd consequence arising as a result of use or reliance upon any information contained in or omitted from this document. Approved By: Kim Gauld-Clark Any persons intending to use this document should satisfy themselves as to its applicability for their intended purpose. Date of Approval April 2015 Where appropriate, the user of this document has the Revision A obligation to employ safe working practices for any activities referred to and to adopt specific practices appropriate to local conditions.

Triton Knoll Offshore Wind Farm Ltd Triton Knoll Offshore Wind Farm Limited have been awarded Auckland House EU TEN-E funding to support the development of the Triton Great Western Way Knoll Offshore Wind Farm Electrical System located in both Swindon UK Territorial waters and the UK’s Exclusive Economic Zone. Wiltshire, SN5 8ZT The funding which is to be matched will support a number of surveys, engineering reports, and environmental impact T +44 (0)845 720 090 assessment studies for the Triton Knoll Electrical System. The studies will form part of the formal documentation that F +44 (0)845 720 050 will accompany the Development Consent Order which will I www.rweinnogy.com be submitted to the Planning Inspectorate. The sum of €1,159,559 has been granted and the process to reclaim this funding is ongoing. www.rweinnogy.com/tritonknoll [email protected]

ii Triton Knoll Offshore Wind Farm Ltd Triton Knoll Electrical System Environmental Statement - Volume 2

Table of Contents 6 Marine Mammals ...... 6-1 Introduction ...... 6-1 Statutory and policy context ...... 6-1 Consultation and scoping ...... 6-3 Scope and methodology ...... 6-6 Existing environment ...... 6-10 Key parameters for assessment ...... 6-13 Environmental assessment: construction phase ...... 6-15 Environmental assessment: operational phase ...... 6-15 Environmental assessment: decommissioning phase ...... 6-16 Environmental assessment: cumulative effects ...... 6-16 Inter-relationships ...... 6-23 Mitigation...... 6-23 Transboundary statement ...... 6-23 Summary of effects ...... 6-23 References ...... 6-24

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6 Marine Mammals o The Offshore Marine Conservation (Natural Habitats, &c.) Regulations 2007 (the Habitats Regulations) which implement the Habitats Directive in Introduction relation to marine areas where the UK has jurisdiction beyond territorial waters (broadly 12 nautical miles to 200 nautical miles); 6.1 This chapter of the Environmental Statement (ES) presents an assessment of potential The Conservation of Habitats and Species Regulations 2010 (the Offshore impacts upon marine mammals arising from the construction, operation and o Habitats Regulations) which implement the Habitats Directive in relation to decommissioning of the offshore components of the proposed Triton Knoll Electrical England and Wales as far as the limit of territorial waters (usually 12 System, as defined in Volume 2; Chapter 1; Offshore Project Description. The chapter nautical miles). also provides an assessment of cumulative effects with other developments in the area. • The Wildlife and Countryside Act 1981 , which gives protection to all cetaceans. 6.2 Reference should also be made to Volume 2 Chapter 7: Nature Conservation, which • The Conservation of Seals Act (1970) and associated Orders, under which both contains additional information of relevance to marine mammals in relation to the harbour seal (Phoca vitulina - also referred to as the common seal) and the European Protected Species and Special Areas of Conservation. grey seal (Halichoerus grypus) are protected all year round. 6.3 The following sections of this chapter include: • The Bern Convention (1979), which lists harbour porpoise in Appendix II. • A summary of relevant legislation and planning policy; • ASCOBANS (Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas, established under the Bonn Convention), which was formulated in • A description of the methodology for the assessment, including details of the study 1992 to offer protection primarily to dolphins and porpoises and to provide area and the approach to the assessment of effects; resources to monitor and carry out research. Ten European countries including the • A summary of consultation with stakeholders; UK have now signed the agreement. • A review of baseline (existing) conditions; • The OSPAR Convention (named for the original Oslo and Paris Conventions) lists • Details of the measures proposed as part of the project to avoid or reduce harbour porpoise as a threatened and declining species. environmental effects, including mitigation and design measures that form part of • UK Post-2010 Biodiversity Framework / United Kingdom Biodiversity Action Plan the project; (UKBAP) under the Convention on Biological Diversity – both the harbour porpoise • An assessment of the likely effects for the construction, operation and and common / harbour seal are BAP priority species. decommissioning phases of the project, taking into account the measures 6.5 The Habitats Directive is of relevance to this chapter for the following reasons: proposed; • Seals and cetaceans are listed on Annex II of the Habitats Directive, with harbour • Identification of any further mitigation measures or monitoring required in relation to porpoise also listed on Annex IV, and seals on Annex V. All cetaceans in the UK likely significant effects; and are classed as European Protected Species (EPS). • Assessment of any cumulative effects with other proposed developments. • Harbour seal is listed as a primary reason for site selection in the Wash and North Norfolk Coast SAC (Special Area for Conservation; sites provided protection under Statutory and policy context the Habitats Directive), whilst grey seal is cited as a qualifying feature of the Humber Estuary SAC and as a non-qualifying feature of the Inner Dowsing, Race 6.4 In undertaking the assessment, the following relevant conventions and legislation have Bank and North Ridge SCI (Site of Comminity Importance) and the Haisborough, been considered: Hammond and Winterton SCI. Both harbour and grey seals are also included as • Marine and Coastal Access Act 2009. non-qualifying species at the more distant (~110 km) Dogger Bank SCI. • EU Council Directive 92/43/EEC on the conservation of natural habitats and of wild • Harbour porpoise is named as a non-qualifying species in the Inner Dowsing, Race flora and fauna (the ‘Habitats Directive’) as transposed into UK legislation through: Bank and North Ridge SCI and the Haisborough, Hammond and Winterton SCI

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and at the more distant (~ 110 km) Dogger Bank SCI. A licence is required if the structures are unlikely to pose a significant collision risk to marine mammals. Further risk of injury or disturbance to EPS is assessed as likely under regulations 41(1)(a) information with regards to the guidance on decision making in relation to marine and (b) the Habitats Regulations and 39(1)(a) and (b) of the Offshore Habitats mammals is presented within Table 6-1. Regulations. However, it is expected that an EPS licence is unlikely to be required 6.10 In addition to legislative and policy aspects highlighted above, the following guidance for the proposed development since construction activities will not include piling of documents have also been referred to when considering potential impacts to marine any structures. mammals for the development: 6.6 For the purposes of the Infrastructure Planning (Applications: Prescribed Forms and • Guidelines for Ecological Impact Assessment in Britain and Ireland, Marine and Procedure) Regulations 2009, Figures 6-1 et seq taken together with this chapter (and Coastal (Institute for Ecology and Environmental Management (IEEM, 2010)); those matters referred to in Volume 2 Chapter 7), fulfil the requirements of Regulation 5(2)(l) in relation to the effects of the proposed development that is the subject of the • Guidelines for data acquisition to support marine environmental assessments of DCO application on statutory and non-statutory sites and features of nature offshore renewable energy projects (Judd, 2012); and conservation, habitats of protected species, important habitats or other diversity • Guidance for Statutory Nature Conservation Agency staff advising on the potential risk features. of seal corkscrew injuries, April 2012. 6.7 Guidance on the issues to be assessed for offshore renewable energy developments Table 6-1 Legislation and policy context in general have been obtained through reference to the National Policy Statements Policy/ 1 2 Key provisions Section where addressed (NPS): EN-1 (Overarching National Policy Statement for Energy) and EN-3 (National legislation Policy Statement for Renewable Energy Infrastructure). Section 5.3 of EN-1 sets out the policy for the Planning Inspectorate (PINS) in relation to generic biodiversity EN-1 Applicants should ensure that the Construction, operation and Overarching Environmental Statement clearly impacts, with EN-3 paragraphs 2.6.58 to 2.6.71 setting out offshore wind-specific decommissioning phases of the Triton NPS for sets out any effects on biodiversity policy. In addition, there are specific considerations for piling noise which Knoll Electrical System have been Energy internationally, nationally and locally assessed as part of the EIA process on apply to offshore wind energy infrastructure proposals with regard to marine mammals, designated sites of ecological or designated sites as well as protected however the Triton Knoll Electrical System does not require any piling to be geological conservation importance, habitats and species (paragraph 6.4). undertaken and as such these provisions are not relevant for the proposed on protected species and on An assessment of impacts arising on the development assessed herein. Key points within the NPS, on issues to be addressed habitats and other species identified sites according to the EIA Regulations are summarised below in Table 6-1. as being of principal importance for the conservation of biodiversity has been undertaken in Volume 2 6.8 Further guidance on the issues to be assessed for the Triton Knoll Electrical System (paragraph 5.3.3 of NPS EN-1). Chapter 7 Nature Conservation. has been obtained through reference to the UK Marine Policy Statement, specifically The only impact specifically addressed in the the guidance and policies contained within the East Inshore and East Offshore The assessment of the effects on marine mammals should include relation to marine mammals in National Marine Plans (Table 6-1). details of: likely feeding areas; Policy Statement for Renewable Infrastructure (NPS EN-3) (2.6.90-2.6.99) known birthing areas/haul out sites; 6.9 With regard to PINS’ decision making, NPS paragraphs 2.6.94 to 2.6.99 set out the is underwater noise emissions. The nursery grounds; known migration issues and mitigation that may be considered. Of relevance to the proposed proposed development will not result in routes; duration of disturbing activity development are the conservation status of marine EPSs (and the need to take significant underwater noise emissions, EN-3 including cumulative/in-combination which are known to be a potentially account of the views of the relevant statutory advisers) and the note that fixed Renewable effects; baseline noise levels; significant source of impact to cetaceans Energy predicted noise levels in relation to in particular. No piling or blasting of rock mortality, permanent threshold shift is anticipated during cable installation. (PTS) and temporary threshold shift

(TTS); soft-start noise levels; and As detailed within OSPAR best environmental practice there are no clear 1 operational noise (NPS EN-3; EN-1 Overarching Energy National Policy Statement indications that noise impacts related to paragraph 2.6.92). 2 EN-3 Renewable Energy Infrastructure National Policy Statement the installation (or removal) and operation

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Policy/ NPS EN-3 guidance on decision making Section where addressed Key provisions Section where addressed legislation (and mitigation) in relation to marine

EN-3 also refers to marine of cables pose a high risk for harming mammals mammals in relation to general marine fauna (OSPAR, 2012). continues to be, undertaken (see Table 6-3). consideration of biodiversity Noise as an impact does not therefore Fixed submerged structures are likely to Collision risk with associated boat traffic and (2.6.59). require assessment in the EIA, as pose little collision risk for marine mammals fixed construction vessels (i.e. jack up reflected in the scoping opinion (The and PINS is not likely to have to refuse to barges) has been scoped out from Planning Inspectorate, 2014) (see grant consent on the grounds that offshore assessment as per the scoping opinion. The paragraph 6.13). wind farm foundations pose a collision risk to risk posed by ducted propellors is assessed East Inshore ECO1 (Environment Policy) Cumulative impacts are considered in the marine mammals. (paragraphs 6.61 et seq), noting the guidance of the NPSs. and Offshore Cumulative impacts affecting the cumulative impact assessment (paragraphs 6.74 et seq). Marine Plan ecosystem of the East marine plans

and adjacent areas (marine, terrestrial) should be addressed in decision-making and plan Consultation and scoping implementation. 6.12 For the Triton Knoll Offshore Wind Farm (TKOWF) array, consultation comments relevant to marine mammal species were mostly concerned with piling activities (RWE, 6.11 The planning process for Nationall Significant Infrastructure Projects (NSIPs) is 3 administered by PINS with the decision on the Development Consent Order (DCO) 2012 ), and are therefore not relevant to the Electrical System development since no being taken by the Secretary of State. NPS EN-3 highlights a number of points to be such methods are proposed (see Volume 2; Chapter 1: Offshore Project Description). taken into account in that decision making process. These are summarised in Table However, during TKOWF Section 42 consultation JNCC requested that an impact 6.2 below. assessment for marine mammal collision risk with ducted propellers be conducted; this is of relevance to the proposed development and as such has been undertaken within

this chapter. Table 6-2 Summary of NPS EN-3 guidance on decision making with regard to marine mammals and relevance to the Triton Knoll Electrical System Assessment 6.13 As part of the EIA process for the Electrical System, a number of consultations were undertaken with various statutory and non-statutory authorities. A formal scoping

NPS EN-3 guidance on decision making Section where addressed opinion was sought from the Secretary of State following submission of the scoping (and mitigation) in relation to marine mammals report (RWE, 2014), with consultation on the Preliminary Environmental Information (RWE, Sept 2014) undertaken under the Planning Act. PINS should be satisfied that the preferred The methods of cable installation which may methods of construction, in particular for be deployed include jetting, mechanical 6.14 The scoping opinion (PINS, 2014; Application Document 8.1) agreed that a range of foundations and the foundation type are trenching and ploughing. The offshore impacts could be scoped out of the ES: designed to reasonably minimise significant platforms (OSPs) considered within the disturbance effects. PINS will need to scoping report (RWE, 2014) are no longer • Underwater noise: The SoS agrees that cable installation is unlikely to result in consider refusing the application unless part of the application (see Table 6-3 and noise emissions likely to impact on cetaceans, and therefore can be scoped out suitable noise mitigation measures can be Volume 2 Chapter 1 Offshore Project from further assessment. imposed by conditions to any development Description) and therefore foundation types, • consent. and the method of installation of them, are Temporary localised increase in suspended sediment concentrations and not considered within the assessment. smothering: The SoS agrees that this can be scoped out from further assessment

The conservation status of marine EPS of The conservation status of species has been cetacean and seals are of relevance to PINS; factored into the assessment of significance. PINS should take into account the views of Consultation with relevant statutory nature the relevant statutory advisors. conservation bodies (SNCBs) has been, and 3 TKOWF ES Volume 2, Chapter 5: Marine Mammals (document reference 05/01/02/05), Table 5.2

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given the mobile nature of marine mammals and the temporary and localised nature of the impact. • Disturbance and displacement of seal from haul out and breeding sites: The SoS agrees this can be scoped out from further assessment given the distance of the seal breeding colonies and that the small area of the cable landfall is unlikely to be used as a seal haul out area given its proximity to settlements and its sandy nature. • Electromagnetic Fields (EMF): The SoS agrees this can be scoped out from further assessment given the mobile nature of marine mammals and the lack of evidence for electro-sensitivity. • Localised changes in distribution of prey during operation: Given the impacts on prey would be limited to a small part of the marine mammals foraging range, the SoS agrees this can be scoped out from further assessment. 6.15 Ongoing consultation has taken place through the development of the Triton Knoll Electrical System EIA Evidence Plan (Evidence Plan) within which agreement has been sought as to the suitability of available evidence, assessment methodologies, and forthcoming guidance where appropriate. Details of the Evidence Plan process are contained in Document 8.16. 6.16 Formal consultation with statutory and non-statutory consultees under Section 42 of the Planning Act 2008, and with community under Section 47 of the Planning Act, on the Preliminary Environmental Information (PEI) took place between 15 October and 19 November 2014. Consultation responses and ongoing informal consultation through the development of an EIA Evidence Plan [Document 8.16] have been important in informing this Environmental Statement and in the development of the technical supporting annexes. Responses received during consultation on the PEI have been reviewed and analysed to: • Ensure TKOWFL has properly considered all the potential impacts of the proposal; and • Consider and take account, where appropriate, of feedback and responses received as TKOWFL progresses the proposal towards application submission. 6.17 Further details on consultation are provided in the Consultation Report (Document 5.1) with specific details of consultation on site selection and alternatives and where consideration of marine mammals has influenced the site selection process is given in Vol 1; Chapter 4 Site selection and alternatives. Responses relating to marine mammals are addressed throughout this chapter. Table 6-3 provides a summary of key points raised, and describes how they have been addressed.

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Table 6-3 Summary of consultation relating to Marine Mammals

Date and consultation phase/ Consultation and key issues raised Section where comment addressed type

Scoping opinion No further surveys are proposed but given the age of this data [the data used in the Subsequent consultation with the relevant authorities has confirmed Scoping baseline] this approach should be agreed with the relevant consultees including that available survey data is adequate (Offshore Ecology Review NE and the MMO. Panel Meeting 15 May 2014).

Scoping opinion The ES should detail the measures of the marine mammal mitigation plan that will be The principal provisions and commitments for the Marine Mammal adopted. Mitigation Protocol (MMMP) are presented in Table 6-8.

Scoping opinion The ES should set out in full the potential risk to European Protected Species (EPS) and Although no piling is proposed as part of the development, and thus confirm if any EPS licences will be required, for example, for harbour porpoises and grey there is unlikely to be a need for an EPS licence, consideration of the seals, [Reference was made to Natural England’s consultation response on the matter, requirements for such is given in Volume 2 Chapter 7: Nature which stated that “Whilst Natural England believes it is unlikely that a European Protected Conservation. Species (EPS) licence will be required for cetaceans for the proposed development, consideration of the requirements for a licence should be included in the ES.”]

Scoping opinion The scoping report states that no mitigation measures to reduce the risk of seal corkscrew The use of ducted propellers on vessels have been considered in injuries will be employed given the distance of the proposed development from SACs relation to pinniped use of the area (see paragraphs 6.61 to 6.72). designated for seals. However, the scoping report states that telemetry studies have identified seals traversing the cable corridor (and states this will be reported in the ES). Therefore the applicant should consider mitigation based on the usage of the site by seals (and not limited solely to seals from SACs) and should be discussed with NE and MMO.

Scoping opinion The SoS welcomes that the assessment of impacts from ducted propellers will be The assessment of potential cumulative effects ducted propellors is undertaken at a cumulative scale but considers the EIA should also include the impacts of presented in paragraphs 6.78 – 6.89. noise and vibration. As offshore platforms are not part of the development and as per OSPAR (2012) guidance there are no significant effects anticipated as a result of vessel/cable installation noise this assessment does not consider noise impacts either in isolation or cumulatively (see paragraph 6.13 and Table 6-2).

Section 42 consultation Clarity and consistency required on maintenance requirements Operation and maintenance phase impacts are considered in Section (Natural England) 6.71 et seq. For the assessment of maximum adverse impacts it is assumed that each cable will require some form of remedial works employing Dynamic Positioning System (DPS) vessels twice during the operational lifetime .

At the end of their operational lifetime, preference would be for cables to remain in-situ The preference to leave cables in-situ is noted; in line with standard practice the decision as to whether the cables are removed or left in- situ will be made at the time based on legal obligations and other requirements at that time

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Scope and methodology • Atlas of Cetacean Distribution in North West European Waters, JNCC Report (Reid et al. 2003); 6.18 As marine mammals are highly mobile, the study area for the proposed development • Annual reports from the Special Committee on Seals (SCOS) produced by the Sea is broad and lies in the southern North Sea, approximately between the mouth of the Mammals Research Unit (e.g. SMRU 2013); Humber estuary and the northern coast of Norfolk. The survey area falls wholly within the study area, with the survey area shown in Figure 6-1. • Norfolk Bird and Mammal Reports from 1991-2007 produced annually by the Norfolk and Norwich Naturalists’ Society, which also periodically review all 6.19 The offshore boundary for the development area includes the TKOWF array area as sightings of marine mammals extending back over 100 years; well as the linear corridor (referred to henceforth as the export cable corridor) beyond the array boundary up to mean high water spring (MHWS4) mark. • Records of marine mammals from the Lincs Environmental Records Centre; 6.20 The features of interest in terms of marine mammals within the array itself were • Information from the Small Cetaceans Abundance in the North Sea (SCANS) and considered in the TKOWF ES, and mitigation measures to limit impacts were included SCANS II projects (Hammond, 2002; SCANS II, 2008); in the Development Consent Order/deemed Marine Licence (DCO/dML) for the wind • Distribution and movements of harbour seals around the coast of Britain: Outer farm. Those relevant measures included in the TKOWF DCO/dML will also be adopted Hebrides, Shetland, Orkney, the Moray Firth, St Andrews Bay, The Wash and the for the installation, operation and decommissioning of the export cable; these are Thames. Report to DTI 2008 (Sharples et al. 2008); and summarised in Table 6-8. The remainder of this chapter is written using the assumption that, where relevant, such measures committed to in the TKOWF • Environmental statements produced for other offshore wind farms in the Greater DCO/dML to protect marine mammals will be employed as standard for the Triton Wash region (e.g. Hornsea Project ONE, Triton Knoll array, Race Bank, and Knoll Electrical System. Sheringham Shoal). 6.21 Data sources for this assessment include broad regional characterisations such as the 6.24 Site-specific baseline surveys carried out for the TKOWF ES included the following: Humber Aggregate Dredging Association (HADA) Marine Aggregate Regional • Thirty-six boat-based surveys (marine mammal/ornithological) commissioned by Environmental Assessment (MAREA) (HADA, 2012) and Outer Humber Regional TKOWFL (Figure 6-1). One or two surveys a month were carried out between Environment Characterisation (REC) (Tappin et al. 2011) studies. Further information January 2008 to December 2009 using a boat that complied with COWRIE relevant to the ES includes the Sea Mammal Research Unit (SMRU) report on seal recommendations and experienced surveyors. The survey route measured 171 km mortalities caused by lacerations (Thompson et al., 2010). This adds to an extensive and covered the array, a 1 km buffer, and a larger control reference area. A total of knowledge of the area based on numerous other developments in the Greater Wash, 6,173 km2 was therefore surveyed for marine mammals over the whole survey such as offshore wind farms. period (further detailed in RWE, 20127); 6.22 A large amount of information on the marine mammal communities in the study area • Telemetry studies of grey and harbour seals tagged by SMRU since 1988 and 5 for the proposed development was compiled in RWE (2012 ). This includes data 2001 respectively (Figure 6-2 and Figure 6-3). SMRU analysed existing data at the obtained both from site-specific baseline surveys and from extensive desk-based time of the TKOWF ES in relation to the TKOWF study area (including the 6 searches, which are described in detail in RWE (2012 ). proposed development); and 6.23 The detailed desk-based review carried out for TKOWF and added to for this • A number of aerial surveys (that recorded data on both birds and marine mammals) application covered the following information sources (in addition to academic papers): have been undertaken in the study area by the Wildfowl and Wetlands Trust (WWT), on behalf of UK Government, using the recommended COWRIE methodology. Marine mammal data from these surveys was summarised by WWT (2009). The Greater

4 As defined by the Marine Management Organisation (2015)

5 TKOWF ES Volume 2, Chapter 5: Marine Mammals (document reference 05/01/02/05)

6 TKOWF ES Volume 3 Annex G1, Marine Mammal Technical Report (document reference 05/01/03/g), Section 2.5. 7 TKOWF ES Volume 3 Annex G1, Marine Mammal Technical Report (document reference 05/01/03/g), Section 2.7-2.10

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Wash region was divided into several ‘GW’ survey blocks, with the development propeller impacts (see Table 6-4). The criteria employed in the assessment for boundary passing through three of these: defining impact magnitude and the significance of effect are presented in Table 6-5 and Table 6-6, respectively. o GW1b: This area encompasses most of the inshore half of the development boundary. A total of seven surveys were conducted over this 6.29 Since the summer of 2008, there has been increasing concern over the number of seal block; four in the period November 2004-April 2005 (DTI, 2006), and three carcasses washed up at various locations on the UK coastline, all displaying the same in the period November 2005-March 2006 (BERR, 2007); fatal injury. They are predominantly harbour seals, mainly adult females, although some grey seals have also been recorded. Each carcass displays a characteristic o GW3: This area encompassed the TKOWF array and most of the offshore half of the development boundary. A total of 14 surveys were conducted wound consisting of a single, smooth edged cut starting on the side of the head and over this block; seven in the period October 2004-August 2005 (DTI, spiralling around the body. The neat edge to the wound strongly suggested the effects 2006), and seven in the period November 2005-August 2006 (BERR, of a blade with a smooth edge applied with considerable force, while the spiral shape 2007); and is consistent with rotation about the longitudinal axis of the animal. 6.30 The injuries had been considered to be consistent with those one might expect if the o GW4: This area encompassed two small portions of the development boundary. A total of 19 surveys were conducted over this block; eight in seals were being drawn through a ducted propeller such as a Kort or rice nozzle or the period October 2004-September 2005 (DTI, 2006); seven in the period some types of Azimuth thruster, although at the moment there has been no definitive November 2005-August 2006 (BERR, 2007); and four in the period evidence to confirm this and this suggestion has subsequently been questioned November 2007- March 2008 (DECC, 2009). (Thomson et al, 2015). Ducted propellers and azimuth thrusters are used for the dynamic positioning of vessels. These boats maintain their position by altering the Assessment criteria and assignment of significance speed and direction of their thrust. This can involve an almost stationary vessel repeatedly starting or reversing its rapidly rotating propellers. This type of operation 6.25 In order to assess the significance of potential effects arising from impacts on had been considered to increase the opportunities for animals to approach propellers receptors (in this instance marine mammals), the value/ sensitivity of the receptor is and be drawn into them (Thompson et al., 2010), however observations made in 2014 considered against the predicted magnitude of the impact using a matrix-based bring this into question. Thompson et al. (2015) record a number of observations made approach. in 2015 of predation of juvenile grey seal pups by adult male grey seals with the 6.26 The sensitivity or value of a receptor (or ecological feature) is dependent upon their resultant injury being characteristic of cuts on the side of the head spiralling around the biodiversity, social, and economic value within a geographic framework of appropriate body. Whilst it is noted that it would be premature to assume that the interactions with reference (IEEM, 2010). The most straightforward context for assessing ecological propellers are not responsible for any of the observed corkscrew injuries, the value is to identify those species and habitats that have a specific biodiversity observations of predation could explain many, if not most of the observed mortalities. importance recognised through international or national legislation or through local, 6.31 The significance of these deaths to the status of the overall UK harbour seal regional or national conservation plans (e.g. Annex II and/or IV species under the population is unknown. This is of particular concern in respect of the harbour seal Habitats Directive, Biodiversity Action Plans (BAPs), existing and recommended populations on the east coast of Scotland and in the Northern Isles which are in Marine Conservation Zones (MCZ) etc.). serious decline. In contrast, counts along the English east coast were 18% higher in 6.27 As agreed in the scoping opinion, this chapter assesses the potential impacts from 2012 than in 2011 and are now above the counts obtained before the 2002 phocine ducted propeller collision and injury. All other impacts, beyond the potential for distemper virus (PDV) epidemic (SMRU, 2013). cumulative impacts associated with ducted propellors have been scoped out of the 6.32 Currently the UK grey seal population is at favourable conservation status, the risk and assessment (see paragraph 6.13). significance of the observed grey seal fatalities is considered much lower than for the 6.28 As the impact assessment is focused on this sole impact (during construction, harbour seals. operation, and decommissioning phases) the approach to determining receptor sensitivity has drawn upon risk categories given in specific internal statutory agency guidance (Anon, 2012), which identifies sensitivity categories for seals to ducted

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6.33 Table 6-4 describes the sensitivity of seals to impacts from ducted propellers, with the Sensitivity Description/ reason high / medium / low risk categories based on internal statutory agency guidance8. 6.34 Magnitude of impact is defined in Table 6-5 through reference to the methodology Seals: Activity proposed to take place between 4 and 30 nautical miles of a employed during the consented TKOWF array and the population estimates presented Medium harbour seal SAC and not covered above, OR therein. Activity proposed to take place within 4 nautical miles of a grey seal SAC 6.35 Criteria for determining the significance of potential effects is described in Table 6-6. Where an effect is classified as major or moderate, this is deemed to be significant in Activity proposed to take place beyond 30 nm distance from a harbour seal EIA terms and mitigation will normally be required to eliminate or reduce the predicted Low SAC, AND impact. Activity proposed to take place beyond 4nm distance from a grey seal SAC 6.36 Whilst seals have been the focus of the corkscrew injury research, there is evidence emerging that harbour porpoise may also be vulnerable to corkscrew injury Very Low No designated SAC protecting harbour or grey seals within 50 nautical miles (Thompson et al., 2010 and updated in Thompson et al, 2015). The evidence for lethal injury from boat collisions to harbour porpoise suggests that incidents are likely to be rare: out of 478 post mortem examinations of harbour porpoise in the UK carried out between 2005 and 2010, only 4 (0.8%) were attributed to boat collisions (CSIP, 2011). As there is currently no guidance on harbour porpoise regarding potential sensitivity to corkscrew injuries, this species has not been considered further herein. However, TKOWFL will continue to monitor information and recommendations that become available with respect to corkscrew type injuries on harbour porpoise. Appropriate mitigation will be discussed in light of further scientific studies and guidelines that become available as required. Table 6-4 Sensitivity/ importance of the environment (based on risk of injury from ducted propellers to harbour and grey seals)

Sensitivity Description/ reason

Seals: Activity proposed to take place within the boundaries of a SAC Very high designated to protect harbour and / or grey seals

Seals: Activity proposed to take place within 4 nautical miles of a harbour seal High SAC and areas where the harbour seal population is in significant decline (the English east coast population is stable / increasing, see SMRU, 2013)

8 Guidance for Statutory Nature Conservation Agency staff advising on the potential risk of seal corkscrew injuries (April 2012)

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Table 6-5 Magnitude of impact Table 6-6 Significance of potential effects

Magnitude Definition Magnitude of impact

Very significant, permanent/ irreversible changes, over the whole feature/ asset, and/or significant alteration to key characteristics or Very High Very High High Medium Low Very Low features of the particular environmental aspect’s character or distinctiveness.

High Significant, permanent/ irreversible changes, over the majority of the feature/ asset, and/or noticeable alteration to key characteristics or Very High Major Major Moderate Minor Minor features of the particular environmental aspect’s character or

distinctiveness. Impact certain or likely to occur.

Guide: 20-80% of population/habitat lost High Major Moderate Minor Minor Negligible Noticeable, temporary (during the project duration) change, over a minority of the feature/ asset, and/or limited but noticeable alteration to key characteristics or features of the particular environmental aspect’s Medium character or distinctiveness.

Receptor sensitivity Receptor Medium Moderate Minor Minor Negligible Negligible Impact will possibly occur. Guide: 5-20 %of the population/ habitat lost

Noticeable, temporary (for part of the project duration) change, or Low Minor Minor Negligible Negligible Negligible barely discernible change for any length of time, over a small area of the feature or asset, and/or slight alteration to key characteristics or features of the particular environmental aspect’s character or Low distinctiveness. Impact unlikely or rare. Very Low Minor Negligible Negligible Negligible Negligible Guide: 1-5% of population/ habitat lost

Note: red shaded cells are defined as significant impacts in EIA terms. Barely discernible temporary change or impact on the feature / asset. Very low Impact unlikely or rare.

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description of the existing environment. It is not intended to repeat or to carry out any Uncertainty and data limitations encountered additional assessment of impacts within the array boundary. 6.37 Boat-based and aerial surveys simultaneously gathered information upon the 6.42 Extensive desk-based review of data gathered for the TKOWF ES, including extensive distribution and abundance of birds and marine mammals. Whereas aerial surveys survey data, found that only harbour porpoise, grey seal and harbour seal were were routinely conducted in conditions that were conducive to detection of marine present in or around the site with any regularity; in agreement with JNCC and Natural mammals, boat-based surveys were also conducted in higher sea states that, whilst England, these were the only species that were included in the assessment of suitable for detection of birds, were thought less likely to detect marine mammals. TKOWF. The baseline information presented here therefore focuses only on these These surveys represent snapshots in time, and seals could not always be identified to three species. species level. Harbour porpoise 6.38 It is acknowledged that counts of marine mammals from visual surveys, either from 6.43 The most robust estimates of harbour porpoise population size in the UK are from the boats or planes, are likely to under-represent the number of marine mammals present, SCANS I which estimated the harbour porpoise population of the North Sea at since marine mammals spend a significant proportion of their time underwater with sea between 210,000 to 340,000 individuals in the summer of 1994; and the SCANS II state markedly affecting the ability to observe marine mammals at the surface. projects which in 2005 provided an estimated North Sea population of 335,000. Thus Moreover, in both boat-based and aerial surveys because the survey platform is indicating that the population did not change significantly between 1994 and 2005 continuously moving even if the marine mammal surfaces regularly there is still the (SCANS II, 2008). The development area is located within the Block U SCANS survey possibility that it may not be visible when the vessel/plane passes along the transect area. SCANS II provided a population estimate of 88,143 harbour porpoise within line. Data thus have to be considered with these limitations in mind. Block U. 6.39 Telemetry studies provide detailed species-specific information on movement but are 6.44 Aerial survey data from 2001-2008 (RWE, 201210) showed that although porpoises are limited to a relatively small number of individuals. recorded in the study area of the TKOWF array, these occur at relatively low densities 6.40 Nevertheless, the data drawn from in this chapter have previously underpinned the compared to the high frequencies in the area of the Silver Pit to the west and the very EIA for the TKOWF array. The approach adopted was consistent with all other high frequencies recorded off the Norfolk coast (WWT, 2009). planned, consented and operational wind farm developments in the Greater Wash. As Grey seals such, the survey methods as applied have provided sufficient data to determine the presence of marine mammal species and an indication of the relative population size 6.45 Grey seals are a qualifying feature of the Humber Estuary Special Area of of one area compared with another. The existing information is considered Conservation (SAC, see Figure 6-1), and come ashore in autumn to form breeding representative of the area and sufficient for the purpose of the impact assessment for colonies at Donna Nook, over 20 km to the north of the landfall of the proposed the electrical system. development; peak sightings in the region in spring and autumn are thought to be related to movement to this breeding site. Existing environment 6.46 Figure 6-1 shows grey seal sightings data from boat-based surveys that were carried 11 6.41 A technical report and ES chapter were produced for the area of the array (RWE, out for the TKOWF EIA (RWE, 2012 ). 20129). The report and the information presented here draw on the site specific survey (covering the area depicted in Figure 6-1) together the wealth of data for the region, which together encompasses the entire export cable corridor and environs. A review of the key findings from that study has been incorporated here into the

10 TKOWF ES Volume 3 Annex G3 - Aerial Surveys of the Greater Wash Area – density estimates for seals and harbour porpoises (document reference 05/01/03/g)

11 TKOWF ES Volume 3 Annex G3 - Aerial Surveys of the Greater Wash Area – density estimates for seals and harbour porpoises (document 9 TKOWF ES Volume 2, Chapter 5: Marine Mammals (document reference 05/01/02/05) reference 05/01/03/g)

6-10 3000000°0'0" 310000 0°10'0"E 320000 0°20'0"E 330000 0°30'0"E 340000 0°40'0"E 350000 0°50'0"E 360000 1°0'0"E 370000 1°10'0"E380000 Legend Proposed Development Humber Estuary SAC Boundary 5940000 TKOWF Array Boundary

Area of site surveyed

Special Area of 53°30'0"N Conservation Common / Harbour Seals 5930000 1 2 3 - 5 Grey Seals 1 5920000 2 3 - 5 Unidentified Seals 53°20'0"N 1 2

5910000 3 - 5

Notes: This map contains data from the following sources: UKHO (2014), Ordnance Survey (2014) and RWE (2012) Coordinate System: WGS 1984 UTM Zone 31N Projection: Transverse Mercator Datum: WGS 1984 Units: Meter

5900000

Source: Global Land Cover Facility, www.landcover.org.

53°10'0"N

02 06/03/2015 Draft LL SL SL

00 23/06/2014 Draft LL SL SL

Rev Date Description Drn Chk App 5890000 Triton Knoll Electrical System

TITLE: Figure 6-1 Seal observations from boat-based surveys 5880000 carried out for the TKOWF ES

The Wash and North Norfolk Coast SAC 0 5 10 Kilometres / 53°0'0"N Source: Esri, DigitalGlobe, GeoEye, i-cubed, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, SCALE: 1:260,657.89@ A3 IGN, IGP, swisstopo, and the GIS User Community REV 02 Document Path:C:\GIS Data\Projects\Triton Knoll Cable 2013-14\Triton Knoll Electrical System Post PEI\Maps\2015_01_GoBe_TKES_ES_Vol2Ch6_MM_6_1.mxd

© Crown copyright, All rights reserved. 2014 License No. EK001-20140601. Contains Ordnance Survey data © Crown copyright and database right 2014. Not to be used for navigation. Triton Knoll Offshore Wind Farm Ltd Triton Knoll Electrical System Environmental Statement - Volume 2

6.47 Grey seals can be particularly wide-ranging, with home ranges of up to several Harbour seals 2 thousand km . Analysis of tagging data from 13 adult grey seals hauled out at Donna 6.48 Harbour seals are a primary reason for the selection of the Wash and North Norfolk 12 Nook (conducted for the TKOWF ES – RWE, 2012 ) considered in relation to the Coast SAC (see Figure 6-1); it is the largest colony of this species in England. Harbour offshore development boundary showed that although some individuals occasionally seals give birth during summer, and this species generally forages close (< 60km) to traversed it, the vast majority of tracks did not (see Figure 6-2). The same conclusions haul-out sites. can be applied to the export cable corridor. 6.49 The Department of Business Enterprise and Regulatory Reform (BERR) commissioned satellite telemetry on harbour seals in the Greater Wash region between October 2003 and March 2005. A total of 3,648 days data were gathered on a total of 24 tagged harbour seals (13 female, 11 male). The seals made repeated trips of relatively long distance and duration. With the exception of one animal that remained within 20 km of the haul-out, seals travelled repeatedly between 75 and 120 km offshore and as far as 220 km to assumed foraging patches. Foraging trips averaged 8.3 days in duration and lasted an individual mean maximum of 16 days. All seals were highly consistent in their individual foraging habits repeatedly travelling to the same areas. No seasonality in behaviour was apparent. All but one of the seals tagged, which used a haul-out site 60 km north of the Wash, remained faithful to the haul-out site at which they were tagged (Sharples et al. 2008). Track lines showed that foraging harbour seals utilised virtually the entire Greater Wash region. The seals also appeared to regularly pass from the Inner Wash out to their main foraging areas along the Silver Pit (Figure 6-3). 6.50 Figure 6-1 shows harbour seal sightings data from boat-based surveys that were carried out for the TKOWF EIA (RWE, 201214).

Figure 6-2 Telemetry tracks of the grey seals which hauled out at Donna Nook13. Each seal is represented by a different colour.

12 TKOWF ES Volume 3 Annex G3 - Aerial Surveys of the Greater Wash Area – density estimates for seals and harbour porpoises (document reference 05/01/03/g)

13 Figure reproduced from figure 5.5 in Volume 2 Chapter 5 Marine Mammals of the TKOWF ES (RWE, 2012), document reference 14 TKOWF ES Volume 3 Annex G3 - Aerial Surveys of the Greater Wash Area – density estimates for seals and harbour porpoises (document 05/01/02/05 reference 05/01/03/g)

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Design envelope assessed

6.52 As agreed at the scoping stage, the only potential impact from the proposed development during construction is an increased risk to marine mammals of injury resulting from collision with, or entrainment into, ducted propellers used by dynamically positioned (DP) vessels. The realistic maximum adverse scenario assumes that vessels with ducted propellers will be used during cable installation and repairs. 6.53 Offshore cable installation works are typically carried out under calm metocean conditions which might be anticipated to occur during the summer months, however construction activities could take place at any time during the calendar year. 6.54 For the purpose of this chapter, the realistic maximum adverse scenario (as highlighted in Table 6-7) for cable installation works is as follows: • A maximum of six cable circuits, with a maximum of two cables being laid simultaneously, though activity would not occur simultaneously along the entire circuit length at any given point in time; • The installation works could take up to 12 months (spread over two years), • Each cable would require a maximum total of 11 vessels to complete all stages of the installation works, though these would not all be operating simultaneously; • A maximum of 20 vessels using ducted propellers could be operating simultaneously Figure 6-3 The telemetry tracks of the harbour seals which hauled-out in the Wash (data at any given point in time. 15 from Sharples et al. 2008, figure reproduced from RWE, 2012 ). Each seal is 6.55 Once installed, it is envisaged that there will be up to 12 maintenance events (2 per represented by a different colour. cable) during the lifetime of the project. In the event a fault does develop, a repair would be effected by maintenance vessels potentially using ducted propellers. Repairs would involve locating the fault, exposing the cable at this point, recovering the cable Key parameters for assessment on to the vessel, splicing in a new section, re-laying and finally re-burying the cable. 6.51 The key parameters for assessment, i.e. maximum adverse scenario, for each of the 6.56 When use of the cables is no longer required they could either be recovered for impacts on marine mammals during construction, operational and decommissioning material reuse through methods similar to that used for installation or else could be left phases are presented in Table 6-7. The assessment of the maximum adverse in situ to prevent disturbance of the seabed. Currently best practice is to leave in situ. scenario for each receptor establishes the maximum potential adverse impact as a A decommissioning plan will be developed in line with legal and any other result and, therefore, any other scenarios (within the Rochdale envelope) will have requirements. The maximum adverse scenario assumes that the cables are removed impacts of equal to or less than those discussed within the following assessment. utilising the same vessel parameters as per the construction phase i.e. a maximum of 20 vessels utilising ducted propellors operating simultaneously.

15 Volume 2 Chapter 5, Marine Mammals, document reference 05/01/02/05, figure 5.6

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Table 6-7 Design envelope scenario assessed Embedded mitigation Maximum adverse Potential effect Justification scenario assessed 6.57 Mitigation measures that were identified and adopted as part of the evolution of the Construction project design (embedded into the project design) and that are relevant to marine mammals are listed inTable 6-8. General mitigation measures, which would apply to all The greatest potential for seals to be exposed to DPs parts of the electrical transmission works, are set out first. Thereafter mitigation would result from the maximum potential number of measures that would apply specifically to marine mammal issues associated with the DP vessels being used for construction along the entire cable route, and for the construction period to cable route are described separately. Maximum vessels last for 12 months, although vessels would only 6.58 There will be embedded mitigation in the form of a marine mammal mitigation plan for using ducted operate at given location for short periods. the array, with appropriate reference to that stipulated in the TKOWF DCO, with the propellers operating mitigation proposed for the Triton Knoll Electrical Infrastructure summarised inTable 6- simultaneously at Two vessel spreads may be working at any one time any given time = 20 (in different locations along the cable route), consisting 8. Any measures which apply to inter-array cabling will also be adopted for the export Impacts from (10 per spread); of a combination of the following (of which potentially cable. dynamic Maximum duration all but the barge may have DPs: 6.59 Currently, best practice is outlined by ‘Guidance for [Statutory Nature Conservation positioning of works = 12 vessels months (spread over 1 x Large/Capable DP Floating vessel for the main run Agency] staff advising on the potential risk of seal corkscrew injuries, April 2012’. This two years); of offshore cable installation guidance divides offshore activities into high, medium or low risk based on the Length of each 1 x Flat-Bottomed Barge for the shallows / beach minimum distance from the activity to SACs designated for seals, with SACs cable circuit 2 x Anchor Handling Tug for assisting the barge designated for harbour seals identified as representing higher risk. (maximum of six): 6 x Dedicated support and survey vessels 66km Table 6-8 Embedded mitigation relating to Marine Mammals The maximum adverse combination of DP vessels operating simultaneously would be a maximum of 10 Parameter Mitigation measures embedded into the project design per spread. Construction Operation In the eventuality of vessels with ducted propellers being used (during construction, repair, maintenance or decommissioning), The maximum adverse scenario during the operational Impacts from 12 maintenance phase of the Triton Knoll Electrical System is the use TKOWFL would agree appropriate mitigation with regulatory authorities in accordance with relevant guidance and best dynamic events (2 per cable) of jack up barges within the nearshore. The maximum Impacts from positioning during the lifetime of number anticipated is two events per cable during the practice at the time (this commitment has been made for work ducted vessels the project lifetime of the project, resulting in 12 maintenance within the Array and will also be adopted for the export cable propellers events using jack-up barges. route). Decommissioning Please refer to section 2.6 of the Mitigation Strategy (Document Impacts from 8.15) which provides full details of where this mitigation will be Based on current best practice cables would be left in dynamic As for construction secured within any consent granted for the Electrical System. situ.However, if they are recovered, the methods will positioning phase be similar to those used in construction. Operation vessels Impacts from ducted as above propellers Decommissioning

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be low. On this basis, the potential magnitude of impact on grey seal populations is Parameter Mitigation measures embedded into the project design classed as low. Impacts from 6.65 Given the predicted low magnitude of impact on grey seal populations, and the low ducted as above sensitivity of the receptor, overall significance of adverse effect on grey seal propellers populations is considered to be negligible. 6.60 Full details of the mitigation referred to within this table and associated with this Harbour seals chapter are set out within section 2.6 of the Mitigation Strategy (Document 8.15). That strategy also shows where this mitigation will be secured within any consent granted 6.66 As the shortest distance from the offshore development boundary to the nearest part for the Electrical System. of the Wash and North Norfolk SAC (and also the Gibraltar Point haul out site), designated for harbour seals, is approximately 14.2km (7.6 nautical miles), this would Environmental assessment: construction phase place the proposed development in the ‘medium’ risk category (i.e. between 4-30 nautical miles). Thus, the sensitivity of the receptor is classed as medium. Injury resulting from collision with, or entrainment into, ducted propellers 6.67 Harbour seals have breeding and haul-out sites in the Wash and at Gibraltar Point. 6.61 As summarised in Table 6-7, the realistic maximum adverse scenario is for 20 vessels Evidence from telemetry studies indicates that harbour seals travel regularly between using ducted propellers operating along the cable route at any given point in time, over these sites and feeding areas in the Silver Pit, traversing the cable route to the south a maximum construction period of 12 months which may be spread over the two year of the Silver Pit. DP vessels would be operating along this section of the route for part construction phase. Embedded mitigation measures are summarised in Table 6-8 of the construction period only, therefore the magnitude of impact on harbour seal Please refer to section 2.6 of the Mitigation Strategy (Document 8.15) which provides populations is predicted to be low. full details of where this mitigation will be secured within any consent granted for the 6.68 Given the predicted low magnitude of impact on harbour seal populations, and the Electrical System. medium sensitivity of the receptor, overall significance of the adverse effect on 6.62 Two receptors are considered for this impact: grey seal populations, and harbour seal harbour seal populations is considered to be negligible. populations. As stated in paragraph 6.36, harbour porpoise are not included as a 6.69 The recommended mitigation measures for the ‘medium’ risk category as per the receptor in this impact assessment, as the evidence for lethal injury from boat statutory agency guidance referred to above are as follows: collisions to marine mammals suggests that collision incidents are rare for this species. • Consider alternatives to using ducted propellers; and Grey seals • Avoid the (harbour seal) breeding season (defined as 1st June-31st August) if possible. 6.63 For grey seals, the shortest distance to the Humber SAC from the offshore development boundary (i.e. to the export cable corridor) is approximately 16 km or 8.6 6.70 However, as no potentially significant construction impacts to marine mammals are nautical miles. This represents ‘low’ risk (> 4 nautical miles from a grey seal SAC) predicted from the proposed development other than the negligible impacts from DP according to the statutory advisory body guidance referred to above (with no vessels, no further mitigation beyond that identified in Table 6-8 specifically for DP recommended mitigation measures at this low risk level). The sensitivity of the vessels is necessary and no monitoring is proposed. Please refer to section 2.6 of the receptor, therefore, is classed as low for the grey seal population in the area. Mitigation Strategy (Document 8.15) which provides full details of where this mitigation will be secured within any consent granted for the Electrical System. 6.64 The baseline environmental information highlights that there are grey seal breeding colonies at Donna Nook. Telemetry data showed that seals from these colonies only Environmental assessment: operational phase occasionally traversed the development area. Table 6-7 indicates that a maximum of 20 DP vessels operating at any given time, however, these would not be Injury resulting from collision with, or entrainment in, ducted propellers simultaneously operating along the length entire cable route, and the relatively low 6.71 If maintenance or repair activities are required during the operational life of the frequency of tracks recorded traversing the area, the risk of encounter is considered to proposed development, and if these activities involve the use of DP vessels, there may

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be a risk of injury or mortality to marine mammals. The duration of any maintenance allocated into ‘Tiers’, reflecting their current stage within the planning and development works (12 events during the operational phase) would be shorter than that for process. construction and the spatial extent of any maintenance works would be much smaller. 6.77 The proposed tier structure that is intended to ensure that there is a clear The magnitude of any potential impacts would therefore be lower than those for the understanding of the level of confidence in the cumulative assessments provided in construction phase. The potential effects arising from operation and maintenance are the Triton Knoll Electrical System EIA is as follows: therefore considered to be of negligible significance, therefore no further mitigation is necessary and no monitoring is proposed. Tier 1 6.78 Tier 1 projects comprise those other projects / plans currently under construction and/ Environmental assessment: decommissioning phase or those consented but not yet implemented, and/ or those submitted but not yet determined where data confidence for the projects falling within this category is high. Injury resulting from collision with, or entrainment in, ducted propellers 6.79 Built and operational projects are included within the cumulative assessment where 6.72 If the cable (and any associated material, e.g. cable protection) is recovered and they have not been included within the environmental characterisation survey, i.e. they vessels with ducted propellers are used, potential impacts will be equivalent to (and no greater than) those during construction. were not operational when baseline surveys were undertaken, and/ or any residual impact may not have yet fed through to and been captured in estimates of ‘baseline’ 6.73 Based on the assumption that the impacts associated with decommissioning will be no conditions or there is an ongoing effect. greater than those arising from construction the potential effects are considered to be 6.80 The Tier 1 assessment considers the potential effects arising from the Triton Knoll of negligible significance during the decommissioning phase of this development. Electrical System together with impacts and effects arising from relevant projects / Environmental assessment: cumulative effects plans categorised as Tier 1 projects. Tier 2 6.74 Cumulative effects refer to effects upon receptors arising from the Triton Knoll Electrical System when considered in addition to those arising from other proposed 6.81 Tier 2 projects comprise those projects/ plans that are consented but not yet developments and activities and any other reasonably foreseeable project(s). In this implemented and/ or submitted applications not yet determined and / or where detailed context the term project(s) is considered to refer to any past, present or reasonably scoping reports are available where data confidence for the projects falling into this forseeable project, programme or plan that could result in an additive impact with the category is medium. This includes projects that are expected to be submitted over a Triton Knoll Electrical System. similar timeframe to that of the Triton Knoll Electrical System. 6.75 The approach to cumulative assessment for the Triton Knoll Electrical System takes 6.82 The Tier 2 assessment considers the potential effects arising from the Triton Knoll into account the Cumulative Impact Assessment Guidelines issued by RenewableUK Electrical System together with impacts and effects arising from projects included in in June 2013, together with the PINS ‘Advice Note 9: Rochdale Approach’, comments Tier 1 and those categorised as Tier 2 projects. made in response to other renewable energy developments within the southern North Tier 3 Sea, and relevant National policy. Full details of the approach to cumulative 6.83 Tier 3 projects comprise those for which a developer has notified the relevant planning assessment is provided within the accompanying annex (Volume 1; Annex 3.1) authority in writing that they intend to submit an application in the future. This includes entitled “Approach to Cumulative and Inter-relationships Impact Assessment for the projects where a scoping report may be available, but where data presented is limited Triton Knoll Electrical System”, which should be read alongside this ES chapter. and / or data confidence is low. 6.76 There can be some uncertainty in terms of the status of some projects as it is often 6.84 The Tier 3 assessment would consider the potential effects arising from the Triton very difficult to establish whether a development has been lawfully implemented and Knoll Electrical System together with impacts and effects arising from projects included determining construction stages and timescales may not always be achievable due to in Tiers 1, 2 and 3. However, the lack of information for projects categorised as Tier 3, a lack of available information. For this reason the status of each project is based on with attendant low data confidence, prevents a meaningful assessment of such reasonable assumptions, as described in Annex 3.1. All relevant projects/ plans projects to be undertaken and therefore no detailed Tier 3 assessment has been considered cumulatively alongside the Triton Knoll Electrical System have been

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presented. It should be noted that where scoping reports have provided sufficient detail, such projects have been elevated to Tier 2 to ensure that a comprehensive cumulative assessment, commensurate with the level of information available, has been provided for the Electrical System application. 6.85 The specific projects scoped into this cumulative impact assessment, and the tiers into which they have been allocated are presented in Table 6-9. The operational projects included within the table are included due to their completion/ commission subsequent to the data collection process for the Triton Knoll Electrical System and as such not included within the baseline characterisation. 6.86 Each project, plan or activity has been considered and scoped in or out on the basis of effect–receptor pathway, data confidence and the temporal and spatial scales involved. For the purposes of assessing the impact of the Triton Knoll Electrical System on marine mammals, professional judgement has been used in order to create a shortlist of projects for assessment for this topic. The ‘Approach to Cumulative and Inter-relationships Impact Assessment’ annex provides further detail about the projects proposed for consideration in this ES chapter. 6.87 The specific projects scoped into this cumulative impact assessment that are relevant to marine mammals, and the tiers into which they have been allocated, are presented in Table 6-9 below.

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Table 6-9 Projects for cumulative assessment

Distance Overlap with TK Overlap with TK from TK Dates of Offshore Construction / Electrical System Tier Phase Project / Plan Details Electrical System Electrical Operation (as applicable) (construction (operation phase) System phase)

Offshore Wind Farms

construction phase 2016-2018, plus Race Bank Offshore Wind Farm 2.0km Up to 226 turbines   operational lifetime

Triton Knoll Offshore Wind Farm 0 Up to 288 turbines 2018-2022, plus operational lifetime  

9km to A single vessel visit per Lincs and LID Operation and Lincs and turbine per year for 25 During operational lifetime   Maintenance 11km to years (for both Lincs and Consented LID LID)

Hornsea Project One Offshore Wind   2.1km Up to 332 turbines 2015-2019, plus operational lifetime Farm

Construction 2017-2025 (max 8.5   Submitted/Application Hornsea Project Two 2km 120 – 360 turbines year period in up to four phases) (PEI) plus operational lifetime

Aggregate Extraction Areas Tier 1 Area 105 - East Humber 14km 6.27km2 ongoing   Area 107 - Docking 8.8km 4.36km2 ongoing   Area 197 - Protector Overfalls 4km 26.18km2 ongoing   Area 515/1 - Outer Dowsing 0 33.62km2 ongoing   Area 441/1 - Outer Dowsing 10km 13.25km2 ongoing   Area 441/2 - Outer Dowsing 6km 34.42km2 ongoing   Area 480 3.9km 9.84km2 ongoing   Area 481/1 - Inner Dowsing 3km 6.07km2 ongoing   2 Operational (with on - (with Operational effects) going Area 481/2 - Inner Dowsing 6km 1.93km ongoing   maximum adverse assumption is   Area 106/1 - Humber Estuary 9km 3.94km2 that activity will be ongoing maximum adverse assumption is   Area 106/2 - Humber Estuary 8.5km 3.20km2 that activity will be ongoing Application maximum adverse assumption is   Area 106/3 - Humber Estuary 2.3km 35.36km2 that activity will be ongoing maximum adverse assumption is   Area 400 - North Dowsing 1.6km 14.25km2 Application that activity will be ongoing maximum adverse assumption is   Area 439 - Inner Dowsing 0 26.28km2 that activity will be ongoing

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Distance Overlap with TK Overlap with TK from TK Dates of Offshore Construction / Electrical System Tier Phase Project / Plan Details Electrical System Electrical Operation (as applicable) (construction (operation phase) System phase) maximum adverse assumption is   Area 493 - Humber Overfalls 3km 12.21km2 that activity will be ongoing maximum adverse assumption is Area 514/4 - Humber 4 13km 22.02km2   that activity will be ongoing Disposal Sites Lincs Offshore Wind Farm Disposal of construction Operational 4.6km Construction 2010 - 2013  none Disposal Site16 related material Triton Knoll Offshore Wind Farm Disposal of construction Consented 0 Construction 2018 - 2024  none Disposal Site related material

Oil and Gas Licence Blocks

Start date: 05/07/2012 47/13b Oil & Gas Licence Blocks 6.3km Contingent well   Anticipated end date: 31/01/2038

Start date: 05/07/2012 47/14d Oil & Gas Licence Blocks 6km Contingent well   Anticipated end date: 31/01/2038

Start date: 10/04/2013 Tier 2 47/15d Oil & Gas Licence Blocks 12km Drill-or-drop   Anticipated end date: 31/12/2038

Start date: 05/07/2012 47/18 Oil & Gas Licence Blocks 6km Contingent well   Anticipated end date: 31/01/2038

Start date: 05/07/2012 47/19b Oil & Gas Licence Blocks 0 Contingent well   Anticipated end date: 31/01/2038 Start date: 10/04/2013 48/11e Oil & Gas Licence Blocks 5.7km Drill-or-drop  

Consented Anticipated end date: 31/12/2038

16 The Lincs OWF disposal site is licensed as ongoing within released metadata; it was however licenced for the sole purpose of construction related material and as the project is now post-construction use of the disposal site is not considered further.

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Table 6-10 Cumulative Rochdale Envelope

Potential Impact Direct / indirect Maximum adverse scenario Justification construction

Electrical System: maximum of 20 DP vessels operating at any given time during the construction period Offshore wind farms: For Hornsea Project 2, a maximum of 42 vessels with ducted propellers will be active at any given time during construction (SMartWind, 2014). For Lincs and LID, up to one O&M visit per turbine is anticipated to occur per year. Therefore for the period of installation of the cable at Triton Knoll, expected to take up to 12 months spread over two years, up to 75 vessel visits for Lincs and 54 visits to LID would be made. Tier 1: Such visits would not be expected to be made concurrently and a similar adherence to JNCC mitigation is anticipated for Lincs and LID. All projects within Tier 1 In the absence of detailed vessel spread information the assumption is made that Hornsea Impacts from dynamic positioning vessels direct Tier 2: Project 1 have a similar maximum number of DP vessels as Hornsea P2 (40 each), and that All projects within Tier 2 Race Bank and Triton Knoll will have a maximum of 20). Aggregate extraction: On the basis of the HADA (2012) 28 day shipping survey, which recorded an average of 3 aggregate vessels within the entire region and 5 on the peak/busiest day, the maximum adverse scenario for the Triton Knoll Electrical System study area is 3 aggregate vessels working within the area at any given time. Disposal sites: No activity is predicted to occur within the Lincs wind farm disposal site during the lifetime of the Electrical System (as the wind farm construction is complete). Vessels using the Triton Knoll disposal site during are accounted for in the figures for offshore wind farms. Oil and gas licence blocks: Based on the approach of DECC (2010), the assumption is made that a maximum of 1 DP vessel per block will be active at any given time.

Operation

Electrical System: maximum number of vessel movements within the electrical system during the operational period; 12 repair events with each event requiring the use of a maximum of 5 Tier 1: vessels; of these, one is a barge therefore only 4 vesslels using dynamic positioning. All projects within Tier 1 Offshore wind farms: For Race Bank, no information is available, so the assumption is that the impact will be equivalent to that of Triton Knoll offshore wind farm (10 vessels). Impacts from dynamic positioning vessels direct Tier 2: For Lincs and LID, up to one O&M visit per turbine is anticipated to occur per year. Therefore All rojects within Tier 2 for the period of operation of the Triton Knoll cable, up to 75 vessel visits for Lincs and 54 visits to LID would be made. Such visits would not be expected to be made concurrently and a similar adherence to JNCC mitigation is anticipated for Lincs and LID. For Hornsea Project 1, a maximum of 68 DP vessel movements are predicted per year

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Potential Impact Direct / indirect Maximum adverse scenario Justification

(SMartWind 2013). For Hornsea Project 2, a maximum of 11 vessels with ducted propellers are predicted to be active during the operation phase, though the number of DP vessel movements is not quantified (SMartWind, 2014). Assuming each wind farm will have a maximum of 11 DP vessels active at any one time, this gives a maximum total of 44 vessels. Aggregate extraction and oil and gas assumptions remain as per construction phase

Decommissioning

Impacts from dynamic positioning vessels Direct As for construction As for construction

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Cumulative Impact Assessment – construction phase they will be for TK) and that no additional controls or timing restrictions need to be placed on TKES. Injury resulting from collision with, or entrainment in, ducted propellers Cumulative Impact Assessment – operation phase 6.88 For grey seals, the shortest distance to the Humber SAC from the offshore cable corridor (see Figure 6-1) is approximately 16km or 8.6 nautical miles. This represents Injury resulting from collision with, or entrainment in, ducted propellers ‘low’ risk (> 4 nautical miles from a grey seal SAC) according to the statutory advisory body guidance referred to above (with no recommended mitigation measures at this 6.95 As highlighted above, the sensitivity of grey seals is classed as low, and that of low risk level). The sensitivity of grey seals, therefore, is classed as low for the grey harbour seals is classed as medium. seal population in the area. 6.96 The magnitude of the cumulative impact is assessed as low on the basis that all tier 1 6.89 As the shortest distance from the offshore cable corridor to the nearest part of the and tier 2 plans and projects will develop and implement an MMMP (as per DECC Wash and North Norfolk SAC (and also the Gibraltar Point haul out site), designated 2012). for harbour seals, is approximately 14.2km (7.6 nautical miles), this would place the 6.97 Given the predicted low magnitude of impact on harbour and grey seal populations, proposed development in the ‘medium’ risk category (i.e. between 4-30 nautical miles). and the medium sensitivity of the most sensitive receptor, overall significance of Thus, the sensitivity of harbour seals is classed as medium. adverse effect is considered to be negligible. 6.90 Following the guidance presented in the Record of Appropriate Assessment for 6.98 In relation to Tier 1 projects that there are no potential cumulative impacts and as such applications under Section 36 of the Electricity Act 1989 (Docking Shoal, Race Bank there is no need to change or control the TKES scheme. In relation to Tier 2 projects it and Dudgeon) (DECC, 2012), it is noted that a detailed MMMP shall be agreed with is assumed that suitable and reasonable controls will be placed on those projects (as the MMO in consultation with JNCC and Natural England prior to construction of each they will be for TK) and that no additional controls or timing restrictions need to be OWF project. placed on TKES. 6.91 Further, DECC (2012) noted that there is currently insufficient evidence that seal Cumulative Impact Assessment – decommissioning phase corkscrew deaths would be caused by wind farm installation because contracts for construction vessels would not be awarded until consent is granted. The DECC Injury resulting from collision with, or entrainment in, ducted propellers appropriate assessment (DECC, 2012) concluded that DECC and the MMO are content that likely significant effects on breeding harbour seals can be avoided or 6.99 As highlighted above, the sensitivity of grey seals is classed as low, and that of managed using a Marine Mammal Mitigation Protocol. harbour seals is classed as medium. 6.92 On this basis, the potential magnitude of cumulative impact on grey and harbour seal 6.100 The magnitude of the cumulative impact is assessed as low on the basis that all tier 1 populations is classed as low for both tier 1 and tier 2. The conclusion has been and tier 2 plans and projects will develop and implement an MMMP (as per DECC made with due consideration to the distance between the Wash and North Norfolk 2010), and impacts will be no greater than those of the construction phase. SAC and the Humber SAC and the individual projects given in Table 6-9; all of these 6.101 Given the predicted low magnitude of impact on harbour and grey seal populations, projects have an equal or lesser risk associated with them from cork screw injuries as and the medium sensitivity of the most sensitive receptor, overall significance of the Triton Knoll Electrical System. The conclusion is reinforced by the recent findings adverse effect is considered to be negligible. reported by Thompson et al (2015) and as described in paragraph 6.30. 6.102 In relation to Tier 1 projects that there are no potential cumulative impacts and as such 6.93 Given the predicted low magnitude of impact on harbour and grey seal populations, there is no need to change or control the TKES scheme. In relation to Tier 2 projects it and the medium sensitivity of the most sensitive receptor, overall significance of is assumed that suitable and reasonable controls will be placed on those projects (as adverse effect on the three receptors is considered to be negligible. they will be for TK) and that no additional controls or timing restrictions need to be 6.94 In relation to Tier 1 projects that there are no potential cumulative impacts and as such placed on TKES. there is no need to change or control the TKES scheme. In relation to Tier 2 projects it is assumed that suitable and reasonable controls will be placed on those projects (as

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Inter-relationships 6.109 Even adopting the conservative assessment approach described above, it has been found that for all of the marine mammal receptors included in this assessment, the 6.103 Volume 2, Chapter 12: Inter-relationships should be referred to for a summary of all level of effect significance is negligible, and therefore not significant in terms of the potential inter-related effects associated with the proposed development. EIA Regulations (Volume 1 Chapter 3). Mitigation 6.110 Table 6-11 presents a summary of the effects of the proposed development during the construction, operation and decommissioning phases on marine mammals at the 6.104 As identified in the preceding sections there are no significant EIA effects anticipated Triton Knoll Electrical System site. as a result of the proposed development. Beyond those forms of mitigation that have Table 6-11 Summary of predicted impacts of the Triton Knoll Electrical System been embedded within the assessment such as development of an agreed MMMP no Possible mitigation further mitigation measures are considerd necessary. Please refer to section 2.6 of Description of impact Effect Residual effect the Mitigation Strategy (Document 8.15) which provides full details of where this measures mitigation will be secured within any consent granted for the Electrical System. Construction Transboundary statement Injury resulting from collision with, or Negligible N/A Negligible entrainment into, ducted propellers 6.105 Following completion of a transboundary screening matrix (PINS reference EN020019) and in agreement with The Planning Inspectorate, it is considered that transboundary Operation impacts are not likely to arise as a result of this development (see Volume 1 Annex 3.2). Transboundary effects are therefore not considered further. Injury resulting from collision with, or Negligible N/A Negligible entrainment in, ducted propellers Summary of effects Decommissioning 6.106 This chapter has investigated potential effects on marine mammal receptors arising from the Triton Knoll Electrical System. The range of potential impacts and associated Injury resulting from collision with, or Negligible N/A Negligible effects considered has been informed by scoping responses, the subsequent formal entrainment in, ducted propellers and informal consultation completed (Table 6-3) as well as reference to existing policy and guidance. This process narrowed the range of impacts considered to a single relevant potential impact during the construction, operation and decommissioning Possible mitigation Description of impact Effect Residual effect phases of the development: the potential for injury resulting from collisions with, or measures entrainment into, ducted propellers. Cumulative effects 6.107 Cumulative impacts were also considered and an assessment was carried out looking at the potential for interaction with increased vessel traffic as a result of the combined Injury resulting from collision with, or activities of export cable installation and other industrial activities in the study area. entrainment in, ducted propellers during construction during Negligible N/A Negligible These include aggregate extraction operations, construction of offshore wind farms as construction, operation and well as dredge disposal activities. decommissioning 6.108 These potential impacts have been investigated using a combination of methods including analytical techniques, the existing evidence base and numerical modelling. In accordance with the requirements of the Rochdale Envelope approach to EIA, the maximum adverse characteristics of the proposed development have been considered thereby providing a highly conservative assessment.

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• Judd, A. (2012) Guidelines for data acquisition to support marine environmental References assessments of offshore renewable energy projects. Cefas contract report: ME5403 – Module 15 • BERR (2007) Aerial surveys of Waterbirds in Strategic Wind Farm Areas: 2005/06 http://www.marinemanagement.org.uk/licensing/groups/documents/orelg/e5403.pdf Final report. Available from: http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None& • OSPAR. (2012) Guidelines on Best environmental Practice (BEP) in cable laying and Completed=0&ProjectID=14004 operation (Agreement 2012-2). OSPAR 12/22/1, Annex 14) • CSIP (2011) UK Cetaceans Strandings Investigations Programme Final Report for the • Reid, J B, Evans, P G H and Northridge, S P. (2003) Atlas of cetacean distribution in period 1st January 2005 – 31st December 2010. Available from: north-west European waters. JNCC, Peterborough, UK. http://ukstrandings.org/csip-reports/ • RWE (2012) Triton Knoll Offshore Wind Farm Environmental Statement • DECC (2009) Aerial surveys of Waterbirds in the UK: 2007/08. WWT Consulting • RWE (2014) Triton Knoll Offshore Wind Farm Electrical System Environmental Impact report. Available from: Assessment Scoping Report http://infrastructure.planningportal.gov.uk/projects/east- https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/196490/ midlands/triton-knoll-electrical-system/ OES_Aerial_Surveys_2007_08.pdf • SCANS-II (2008) Small Cetaceans in the European Atlantic and North Sea. Final • DECC, 2010. Offshore Oil & Gas Licensing 25th Seaward Round; Southern North Sea Report to the European Commission under project LIFE04NAT/GB/000245. Available Blocks 42/27d, 42/27e, 43/13b, 43/14a, 43/15c, 43/17, 43/18, 43/19b, 43/20d, 43/23, at: http://biology.standrews.ac.uk/scans2/inner-finalReport.html. 44/7, 44/8, 44/9, 44/11b, 44/12b, 44/16d, 44/19f, 48/8c, 48/22, 48/23a, 48/29b, 49/7, • Sharples, R J, Matthiopoulos, J and Hammond, P S. (2008) Distribution and 49/8b and 49/13. Phase 2 Screening/ Appropriate Assessment February 2010 movements of harbour seals around the coast of Britain: Outer Hebrides, Shetland, • DECC (2012) Record of the Appropriate Assessment undertaken for applications Orkney, the Moray Firth, St Andrews Bay, The Wash and the Thames. Report to DTI. under Section 36 of the Electricity Act 1989. Projects: Docking Shoal offshore wind • SMartWind (2013) Hornsea Project One Offshore Wind Farm Environmental farm, Race Bank offshore wind farm, Dudgeon offshore wind farm Statement • DTI (2006) Aerial surveys of Waterbirds in Strategic Wind Farm Areas: 2004/05 Final • SMartWind (2014) Hornsea Project Two Offshore Wind Farm Draft Environmental report. Available from: Statement http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file32485.pdf • SMRU (2013) SCOS Main Advice. Scientific Advice on Matters Related to the • Hammond, P.S., Berggren, P., Benke, H., Borchers, D.L., Collet, A., Heide-Jørgensen, M.P., Heimlich, S., Hiby, A.R., Leopold, M.F. & Øien, N. (2002). Abundance of harbour Management of Seal Populations: 2013 http://www.smru.st- and.ac.uk/documents/1619.pdf porpoises and other cetaceans in the North Sea and adjacent waters. Journal of Applied Ecology 39: 361-376 • Tappin, D R, Pearce, B, Fitch, S, Dove, D, Geary, B, Hill, J M, Chambers, C, Bates, R, • Humber Aggregate Dredging Association (HADA) (2012) Marine Aggregate Regional Pinnion, J, Diaz Doce, D, Green, M, Gallyot, J, Georgiou, L, Brutto, D, Marzialetti, S, Hopla, E, Ramsay, E, and Fielding, H (2011) The Humber Regional Environmental Environmental Assessment of the Humber and Outer Wash Region. Volume I: Characterisation. British Geological Survey Open Report OR/10/54. 357pp. Chapters 1-6. Issued May 2012. • The Planning Inspectorate (2014) Scoping Opinion. Proposed Triton Knoll Electrical • Anon (2012) Guidance for Statutory Nature Conservation Agency staff advising on the System http://infrastructure.planningportal.gov.uk/projects/east-midlands/triton-knoll- potential risk of seal corkscrew injuries, April 2012 electrical-system/ • IEEM (2010) Guidelines for Ecological Impact Assessment in Britain and Ireland: • Thompson D., Bexton S., Brownlow A., Wood D., Patterson T., Pye, K., Lonergan, M. Marine and Coastal. Institute of Ecology and Environmental Management. Final Milne, R. (2010) Report on recent seal mortalities in UK waters caused by extensive version 5 August 2010. lacerations. SMRU report available from: http://www.smru.st- and.ac.uk/documents/366.pdf

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• Thompson, D., Onoufriou, J., Brownlow, A., Bishop, A. (2015) Preliminary report on predation by adudlt grey seals on grey seal pups as a possible explanation for corkscrew injury patterns seen in the unexplained seal deaths. SMRU report available from: http://www.smru.st-and.ac.uk/documents/2173.pdf • Wildfowl and Wetland Trust (WWT) (2009). Distributions of Cetaceans, Seals, Turtles, Sharks and Ocean Sunfish recorded from Aerial Surveys 2001-2008. WWT Consulting. Report to Department of Energy and Climate Change.

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