Corrib Ocean Bottom Cable Seismic Survey

Transcription

1 . se ru he ot to f c Fo op r i yr ns ig pe ht ct ow ion ne pu r r rp eq os ui es re o d nl fo y. ra ny Shell Exploration and Production Ireland Ltd Co ns en Corrib Ocean Bottom Cable Seismic Survey Natura Impact Statement (to support the Appropriate Assessment Process for the proposed West Connacht Coast SAC) FEBRUARY 2013 EPA Export :23:28:17

2 General notes Project No: Title: Corrib Ocean Bottom Cable Seismic Survey Natura Impact Statement (to support the Appropriate Assessment Process for the proposed West Connacht Coast SAC) Contracting Authority: Shell Exploration and Production Ireland Ltd Issue Date: 28th February 2013 Issuing Office: Helsby Prepared by: Authorised by: Andrew Bendell BSc Marine Biology with Oceanography MSc Marine Resource Development and Protection Dr. Dave Watson BSc Marine and Freshwater Biology PhD Marine Chemistry Author Date: 28th February 2013 Technical Reviewer Date: 28th February 2013 RSK/He/P/P40036/44/NIS for OBC rev00 i EPA Export :23:28:17

3 Contents 1 INTRODUCTION THE REQUIREMENT FOR AN ASSESSMENT UNDER ARTICLE THE AIM OF THIS REPORT BACKGROUND - AN OVERVIEW OF THE CORRIB GAS PROJECT Government Departments THE APPROPRIATE ASSESSMENT PROCESS INTRODUCTION STAGES ALTERNATIVES APPROACH TO THE ASSESSMENT INTRODUCTION IMPACT ASSESSMENT METHODOLOGY Introduction Evaluating the Potential Impacts DESCRIPTION OF THE PROJECT NATURA 2000 SITE CONSERVATION OBJECTIVES ASSESSMENT OF LIKELY EFFECTS CONSIDERATION OF SIGNIFICANCE IMPACTS OF NOISE ON MARINE FAUNA IMPACTS OF SEISMIC SOURCE SOUND ON ANNEX IV MARINE MAMMALS Impacts on Marine Mammals in the Corrib Field IMPACTS ON NATURA 2000 SITES Discussion of impacts on habitats in the West Connacht Coast SAC Discussion of impacts on qualifying species for the West Connacht Coast SAC Indirect Sources of Disturbance Cumulative impacts Seabed Trenching and Jet Trenching along the Corrib offshore umbilical route Impacts of seabed trenching operations on bottlenose dolphins in the proposed SAC Localised dredging works in Broadhaven Bay Umbilical Lay Operations Tie-in of the offshore umbilical at the Corrib Offshore Field RSK/He/P/P40036/44/NIS for OBC rev00 ii EPA Export :23:28:17

4 5.6.6 Rock placement works along the route of the Corrib Offshore Umbilical Impacts of rock placement and associated activities on bottlenose dolphins in the proposed SAC General marine survey work and vessel movements Well intervention works at the Corrib Offshore Gas Field CONCLUSION HABITATS Qualifying Habitats Non-Qualifying Habitats Non-Annexed Habitats psac SPECIES Qualifying species for the SAC Non-qualifying, listed faunal species of importance for the psac Annexed species not listed Non-qualifying, listed faunal species of importance for the psac DESIGNATED NATURA 2000 SITES IN THE WIDER LOCALITY REFERENCES RSK/He/P/P40036/44/NIS for OBC rev00 iii EPA Export :23:28:17

5 1 INTRODUCTION 1.1 THE REQUIREMENT FOR AN ASSESSMENT UNDER ARTICLE 6 The requirement for appropriate assessment is set out in Article 6(3) of the EU Habitats Directive (92/43 EEC) 1, which states: any plan or project not directly connected with or necessary to the management of the site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the site's conservation objectives 1.2 THE AIM OF THIS REPORT This Natura Impact Statement (NIS) has been prepared in accordance with the current guidance of the National Parks and Wildlife Service (NPWS) as described in Appropriate Assessment of Plans and Projects in Ireland: Guidance for Planning Authorities (Department of Environment, Heritage and Local Government, 2009 (as revised February 2010) and provides an ecological impact assessment (EcIA) for an Ocean Bottom Cable (OBC) seismic exploration survey and related activities at the Corrib Offshore Gas Field, approximately 65 km off the coast of Co. Mayo, Ireland. The NIS provides the information required in order to establish whether or not the proposed activities either alone or in combination with any other offshore works proposed that may have an overlapping timescale with the primary activity, are likely to have a significant impact on the Natura site in the context of their conservation objectives and specifically on the habitats and species for which the Natura 2000 conservation site has been designated. In the case of the proposed project activities, the proposed Natura 2000 site West Connacht Coast SAC (SAC Site Code ) forms the focus for this NIS, and for which impacts will be assessed. By taking the ecological impact assessment in a step by step manner in relation to the habitats and species of the Natura site, together with its conservation objectives, this report seeks to inform the screening process required as the first stage of the process pursuant to Article 6(3) of the EU Habitats Directive and also to provide full and detailed information as required for the second, that of Appropriate Assessment should the competent authority decide that such an assessment is required. 1.3 BACKGROUND - AN OVERVIEW OF THE CORRIB GAS PROJECT The Corrib natural gas field is located approximately 65 kilometres offshore from the coast of County Mayo. This medium sized gas field is being developed as a subsea tieback facility, connected by an 83 km offshore pipeline to an onshore processing terminal located approximately 9 kilometres inland. The Corrib Field was discovered in 1996 by Enterprise Energy Ireland Ltd, which was subsequently acquired by the Royal Dutch Shell Group in The Corrib Gas Partners are Shell E&P Ireland Limited () (45% - Operator), Statoil Exploration (Ireland) Limited (36.5%) and Vermilion Energy Ireland Limited (18.5%). The Corrib gas field development consists of a series of gas wells and seabed infrastructure in the Corrib field, a manifold that will gather the flow of gas from each of the wells, and a pipeline to the onshore gas terminal located at Bellanaboy Bridge. The 1 Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora, as amended by Council Directive 97/62/EC RSK/He/P/P40036/44/NIS for OBC rev00 1 EPA Export :23:28:17

6 gas pipeline comes ashore at Glengad in Broadhaven Bay from where it will run underground to the Terminal. There will also be a multipurpose umbilical that runs from the Terminal to the Corrib field. A treated water outfall pipeline for the discharge of treated surface water run-off from the Terminal site will run along the route of the pipeline between the Terminal and a point offshore approximately 12.7km from the landfall. A Landfall Valve Installation will be situated close to the landfall of the offshore pipeline, its function being to limit the pressure of the gas in the onshore section of the pipeline. All of the statutory permits and consents necessary to develop the Corrib gas field and associated facilities and infrastructure are in place. As of February 2013 the offshore production facilities have been installed, the 83km offshore section of the Corrib pipeline between the field and the landfall has been laid, and the gas terminal is more than 90% complete. To allow the connection of the Corrib development with the national gas distribution network the 150km Galway to Mayo pipeline was completed in 2006 and is now connected to the Terminal. The 8.3km onshore section of the Corrib pipeline and the offshore umbilical are in construction and will be the last major project elements to be completed. This Natura Impact Statement has been prepared for the proposed 2013 OBC Seismic Survey programme at the Corrib Offshore Gas Field Government Departments Consultations with the National Parks and Wildlife Service (NPWS) of the Department of the Arts, Heritage and the Gaeltacht (DAHG) in relation to the Corrib Gas Project are ongoing. Consultations have also taken place with the Department of Communications, Energy and Natural Resources. RSK/He/P/P40036/44/NIS for OBC rev00 2 EPA Export :23:28:17

7 2 THE APPROPRIATE ASSESSMENT PROCESS 2.1 INTRODUCTION Article 6(3) of the EU Habitats Directive (Directive 92/43/EEC), sets out the requirements to carry out an Appropriate Assessment. The first step of the Appropriate Assessment process is to establish whether, in relation to a particular plan or project, Appropriate Assessment is required. Article 6(3) states: Any plan or project not directly connected with or necessary to the management of the site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the site s conservation objectives. A number of guidance documents on the appropriate assessment process have been referred to during the preparation of this NIS. These are: Appropriate Assessment of Plans and Projects in Ireland - Guidance for Planning Authorities (NPWS 2009, Revised February 2010) EU Guidance document on Article 6(4) of the 'Habitats Directive' 92/43/EEC (2007) Assessment of plans and projects significantly affecting Natura 2000 sites. Methodological guidance on the provisions of Article 6(3) and (4) of the Habitats Directive 92/43/EEC (Nov published 2002) Managing Natura 2000 Sites: The provisions of Article 6 of the Habitats Directive 92/43/EEC (2000). Should a decision be reached to the effect that it cannot be said with sufficient certainty that the development will not have any significant effect on the Natura 2000 sites, then, as is stated above, it is necessary and appropriate to carry out an appropriate assessment of the implications of the development for the sites in view of their conservation objectives. The guidance for Appropriate Assessment (NPWS, 2009, revised February 2010) states: AA is an impact assessment process that fits within the decision-making framework and tests of Articles 6(3) and 6(4) and, for the purposes of this guidance, it comprises two main elements. Firstly a Natura Impact Statement i.e. a statement of the likely and possible impacts of the plan or project on a Natura 2000 site (abbreviated in the following guidance to NIS ) must be prepared. This comprises a comprehensive ecological impact assessment of a plan or project; it examines the direct and indirect impacts that the plan or project might have on its own or in combination with other plans and projects, on one or more Natura 2000 sites in view of the sites conservation objectives. Secondly, the competent authority carries out the AA, based on the NIS and any other information it may consider necessary. The AA process encompasses all of the processes covered by Article 6(3) of the Habitats Directive, i.e. the screening process, the NIS, the AA by the competent authority, and the record of decisions made by the competent authority at each stage of the process, up to the point at which Article 6(4) may come into play following a determination that a plan or project may adversely affect the integrity of a Natura 2000 site. 2.2 STAGES The European Commission s guidance promotes a fours stage process, as set out in Box 1 below, to complete the Appropriate Assessment, and outlines the tests required at RSK/He/P/P40036/44/NIS for OBC rev00 3 EPA Export :23:28:17

8 each stage. Stages 1 and 2 deal with the main requirements for assessment under Article 6(3). Stage 3 may be part of Article 6(3) or a necessary precursor for Stage 4. This NIS includes the ecological impact assessment and testing required under the provisions of Article 6(3) by means of the first stage of Appropriate Assessment, the screening process (as set out in the EU Guidance documents). For the screening stage, EU guidance 2 states: This stage examines the likely effects of a project or plan, either alone or in combination with other projects or plans, upon a Natura 2000 site and considers whether it can be objectively concluded that these effects will not be significant. This assessment comprises four steps: 1. determining whether the project or plan is directly connected with or necessary to the management of the site; 2. describing the project or plan and the description and characterisation of other projects or plans that in combination have the potential for having significant effects on the Natura 2000 site; 3. identifying the potential effects on the Natura 2000 site; 4. assessing the significance of any effects on the Natura 2000 site. The NIS also provides the information required for the Competent Authority to complete the Appropriate Assessment (Stage 2) should this be necessary in the opinion of the Competent Authority. An evaluation of alternatives has also been provided to demonstrate that all feasible alternatives for the proposed development have been considered and that the option with the least ecological impact has been selected. 2.3 ALTERNATIVES The primary objective of the proposed 3D OBC seismic survey is to acquire data to significantly improve the understanding and associated mapping of the Corrib field gas reservoir, and in particular to assist in determining the best location of future wells to most effectively produce the gas in the reservoir. The existing wells (P1 to P5) were drilled using seismic survey data collected in 1997 and the results of drilling those wells were broadly in line with expectations. However, the data acquired from the drilling of well P6 clearly demonstrated limitations in the quality of the 1997 seismic data. Well P6 encountered geological horizons that were not predicted by the seismic interpretation. A significant improvement in the quality of data is needed to understand the overall structural picture of the Corrib reservoir. On that basis, it is not feasible to carry out further production drilling (e.g. P7) until the uncertainty in the understanding of the reservoir structure is significantly reduced. 2 Paragraph 3.1 of Assessment of plans and projects significantly affecting Natura 2000 sites. Methodological Guidance on the provisions of Article 6(3) and (4) of the Habitats Directive 92/43/EEC (Nov. 2001). RSK/He/P/P40036/44/NIS for OBC rev00 4 EPA Export :23:28:17

9 The 3D OBC seismic data acquisition methodology was chosen following the evaluation of a number of alternatives. This resulted in the selection of Ocean Bottom Cable technology combined with a high level of overlapped results which improves the signal to noise ratio. This technology provides a significant improvement over conventional towed streamer seismic acquisition as it mitigates the multiple problem (spurious reflections) associated with the shallow basalts, which are located immediately beneath the seabed in the area of the Corrib field. RSK/He/P/P40036/44/NIS for OBC rev00 5 EPA Export :23:28:17

10 3 APPROACH TO THE ASSESSMENT 3.1 INTRODUCTION The approach to, and methodology used in, the Ecological Impact Assessment for this Natura Impact Statement has taken due regard of the World Bank definitions for residual impact severity, and the methodologies used for the calculation of residual impact severity are explained in Section 3.2 below. The ecological characteristics of the West Connacht Coast SAC are described in Section 4 of this statement, followed by Assessment of Likely Effects in Section 5. Conclusions are set out in Section 6. An impact risk assessment for Annex IV species of marine mammals for the 2013 OBC seismic survey was submitted to the Department of Communications, Energy and Natural Resources (DCENR) in January This risk assessment was undertaken in accordance with the DCENR s requirements for applications in respect of seismic survey works. This risk assessment document provides detailed technical characteristics of the OBC surveys activities and impacts on Annex IV species of marine mammal (RSK, 2013a). A summary of the 2013 OBC seismic survey is provided in Section IMPACT ASSESSMENT METHODOLOGY Introduction The predicted impacts from scheduled operations (those impacts expected to occur despite the mitigation measures proposed) are often referred to as residual impacts, and are covered in the first part of the risk assessment. Those impacts that have the potential to occur as a result of accidental events are discussed in the second part. The proposed work programmes have been separated in the risk assessment into a number of activities and impacts are identified for each activity. The assessment of impact of the activities associated with the 2013 OBC seismic survey, as well as these works in combination with other works e.g. the Corrib umbilical installation and route survey and stabilisation works, as well as offshore gas field well intervention works on the ecological and socio-economic environment uses a systematic process which involves identification of the project s: Activities / sources of impact. The environmental and socio-economic receptors. The effects of the project. Once these are in place the severity of the initial impacts or consequences can be assessed based on sensitivity of the environmental / socio-economic receptors and the intensity of the effect. Mitigation / protection measures are then applied to the project and the severity of the residual impacts assessed based on their effectiveness. This is presented in Table 5-2. Definitions for scoring intensity, sensitivity and severity are provided in Section below. RSK/He/P/P40036/44/NIS for OBC rev00 6

11 3.2.2 Evaluating the Potential Impacts Intensity For each source of impact the intensity of the effect is defined according to the following criteria: The nature of the change (what is affected and how). Its size and scale. Its geographical extent and distribution. Its duration, frequency and reversibility. The intensity is then scored from 1 (very low) to 4 (high) based on the definitions in Table 3.1 Table 3-1: Definitions to Assist with Scoring Intensity Score Definition 1 Very low Direct or indirect impacts on habitat and species largely not discernible. 2 Low Minor shift away from baseline conditions. Minor disruption of behaviour or species interactions not impacting overall health/integrity of the population of the species. Affects a specific group of localised individuals within a population over a short time period (one generation or less), but does not affect other trophic levels or the population itself. 3 Medium Direct or indirect impacts to one or more key elements / features of the baseline conditions (habitat and / or species) such that postdevelopment character / composition / attributes of baseline will be partially changed but the overall integrity of the habitat or species is not threatened. Affects a portion of a population and may bring about a change in abundance and / or distribution over one or more generations, but does not threaten the integrity of that population or any population dependent on it. 4 High Major direct or indirect impacts to key elements / features of the baseline conditions such that post-development character / composition / attributes will be fundamentally changed and the overall integrity of the habitat or species is threatened. Affects an entire population or species in sufficient magnitude to cause a decline in abundance and / or change in distribution beyond which natural recruitment (reproduction, immigration from unaffected areas) would not return that population or species, or any population or species dependent upon it, to its former level within several generations. RSK/He/P/P40036/44/NIS for OBC rev00 7

12 Sensitivity The sensitivity of the environmental receptor has been defined for this project taking into account such matters as the presence of protected areas or sensitive species, its ecosystem function, or its economic value. The sensitivity is then scored from 1 (very low) to 4 (high) based on the definitions in Table 3.2 Table 3-2: Definitions to Assist with Scoring Sensitivity Score Definition 1 Negligible sensitivity. Commonly occurring habitats and species, widespread in distribution not subject to significant decline. Low biodiversity value Habitats that are already disturbed, or which are periodically subject to natural disturbance. 2 Low sensitivity or local ecosystem value. Areas of local biodiversity value but not intact, fragile or unique. Widespread common species with low biodiversity value. Habitats that recover quickly following disturbance. 3 Medium sensitivity or regional / national ecosystem value. Sites of regional importance, or designated for protection at national level. Habitats of high species or habitat diversity or naturalness, or recognised as intact or unique, or areas recognised by NGOs as having considerable environmental value (e.g. key bird areas). Regionally or nationally important population of a species, either because of population size or distributional context Species listed as rare at country level. Species in significant decline at national or regional level. Habitats that are unlikely to return to natural conditions without some intervention, but which are capable of assisted recovery. 4 High sensitivity or international ecosystem value. Sites of international importance/designated for protection at international level. Species that are rare at an international level (i.e. listed on the CITES, IUCN lists, or require the designation of SAC / SPA / Ramsar sites). Critical habitats as defined by IFC P-S6 Biodiversity Conservation & Sustainable Natural Resource Management 3 Habitats that are very difficult to restore to natural conditions. 3 Critical Habitat Critical habitats are areas with high biodiversity value, including (i) habitat of significant importance to Critically Endangered and/or Endangered11 species; (ii) habitat of significant importance to endemic and/or restricted-range species; (iii) habitat supporting globally significant concentrations of migratory species and/or congregatory species; (iv) highly threatened and/or unique ecosystems; and/or (v) areas associated with key evolutionary processes. RSK/He/P/P40036/44/NIS for OBC rev00 8

13 Severity The severity of the impact can then be calculated as follows: Severity = Intensity x Sensitivity It is qualified according to a scale, which ranges from negligible to major based on World Bank definitions (environmental only). Definitions of impact severity are provided in Table 3.3 Table 3-3: Definitions of Impact Severity Score Severity Definition 1-2 Negligible Changes in ecosystem that are unlikely to be noticeable (i.e. well within the scope of natural variation). 3-4 Minor Minor adverse changes in an ecosystem. Changes might be noticeable, but fall within the range of normal variation. Effects are short-lived and natural recovery takes place in the short term. It is recognised that potentially a low level of impact may remain. No measurable impacts on European protected species or site. 5-9 Moderate Moderate adverse changes in an ecosystem. Changes may exceed the range of natural variation. Potential for natural recovery in the medium term is good. It is recognised that a low level of impact may remain. Potential for short-term effects on the integrity of a European protected species or site. > 9 Major Substantial adverse changes in an ecosystem (permanent loss of habitat / alteration of a large area / regionally significant habitat / permanent reduction in population numbers). Changes are well outside the range of natural variation and assisted rehabilitation is required. The recovery of affected ecosystem may be protracted. May have long term impacts on the integrity of a European protected species or site. Note: The definitions are intended to categorise predicted impacts following the implementation of mitigation measures or controls. An impact that would have been Significant without action by the Project may be assessed to be Moderate, Minor, or Negligible, after effective mitigation or control measures are in place. 3.3 DESCRIPTION OF THE PROJECT The proposed Corrib Field Ocean Bottom Cable (OBC) seismic survey will take place in the vicinity of the Corrib Offshore Gas Field, as shown in Figure 3.1, in water depths in the range m. The OBC data acquisition will be undertaken by Reservoir Exploration Technology ASA (RXT) on behalf of. The survey work is scheduled to commence early in March 2013 with an estimated duration of approximately 100 days. The main objective of the proposed OBC survey is to acquire approximately 122km 2 fullfold 3-D OBS data over the Corrib field using a dual source, 5-cable OBS survey spread. The 2013 programme will carry on from the 2012 survey, which was curtailed in October 2012 due to poor weather conditions. The field programme will consist of the following main components: RSK/He/P/P40036/44/NIS for OBC rev00 9

14 Mobilisation of vessels (including cable vessel, source vessel and support vessel(s)); Deployment of towed equipment (airgun array); Deployment and retrieval of ocean bottom cables (ongoing throughout survey, as cables are rolled along after each swath); Data acquisition, comprising the bulk of the programme (NB. Vessels may be kept on standby due to adverse weather conditions, equipment repair etc); and Retrieval of equipment and demobilisation from the area. During data acquisition, the source vessel will follow the pre-determined sail lines that may be subject to change depending on prevailing current and wind conditions. The actual distance covered by the source vessel during shooting and recording, during which the airguns will be fired at regular intervals, will be approximately 5,200 km (excluding turns, during which the airguns will continue to be fired). The total line km for the receivers (ocean bottom cables) will be 336 km. The overall survey was planned to consist of 39 swaths in total, plus 3 extra swaths on each end to allow for taper-in and taper out (required to achieve full fold coverage over the survey area). This results in a total source effort of 45 swaths. During 2012 approximately 40% of the overall survey was completed (18 swaths), with 60% (24 swaths plus 3 swaths for taper-out (as the survey will recommence at the point at which it was suspended in 2012, there is no taper-in)) remaining for completion in The source vessel has a starboard and a port array, and will flip flop between these two arrays, acquiring two source lines per source sail line. Per swath, the source vessel acquires three sets of four source sail lines (each km long); two on either side of the active spread, and one in the middle of the active spread (between cables 2 and 3). This results in 12 source sail lines per swath. Once these twelve source sail lines have been acquired, the first cable can be picked up, and the source vessel moves towards the next swath in the survey. The total survey comprises 45 x 12 x = 8,613 km of which 3,413 km has been acquired in 2012, leaving 5,200 km for the 2013 programme. Some of the marine works will generate underwater noise that may impact upon Bottlenose Dolphins (Tursiops truncatus). This species is the single qualifying feature for the West Connacht Coast SAC, located approximate 47.5km from the proposed seismic survey area. The seismic survey acoustic source will generate underwater noise, other sources of noise from project activities could include engines and the deployment and retrieval of ocean bottom cables. The impacts associated with these project activities have been assessed throughout Section 5 of this NIS report. Section 5 also covers other operational discharges from the vessels. RSK/He/P/P40036/44/NIS for OBC rev00 10

15 Natura Impact Statement Co ns en to f c Fo op r i yr ns ig pe ht ct ow ion ne pu r r rp eq os ui es re o d nl fo y. ra ny ot he ru se. Figure 3-1: OBC Seismic Survey Area in relation to the Connacht Coast SAC and the Corrib Offshore Pipeline / Umbilical Route RSK/He/P/P40036/44/NIS for OBC rev00 11

16 4 NATURA 2000 SITE The Natura 2000 site potentially affected by the marine works is: West Connacht Coast SAC (Site code: ). The site consists of a substantial area (66,016 ha) of marine waters lying off the coasts of counties Mayo and Galway in the west of Ireland (see Figure 3.1). The proposed marine works described in this report will not take place within the SAC itself, but at closest will occur at circa 47.5 km from the nearest boundary of the SAC. The Qualifying Interest under the Habitats Directive for this SAC is Bottlenose Dolphins Tursiops truncatus. Although not directly impacting the SAC itself, it is recognized that sound can travel a substantial distance underwater and that harmful or disturbance effects to cetaceans may occur over several kilometers from the source of the noise. The National Parks and Wildlife Service (NPWS) citation states that the West Connacht SAC encompasses a diverse range of shallow marine habitats occurring in waters less than 100 m deep. These include a variety of seabed structures including reefs, islets and sedimentary basins. The site contains physical and hydrographic features believed to be important for Bottlenose Dolphins Tursiops truncatus, one of two cetacean species listed on Annex II of the E.U. Habitats Directive. The physical features include shallow coastal bays, areas of steep seafloor topography and complex areas of strong current flow adjacent to estuaries, coastal headlands and islands, sandbanks, shoals and reefs. Its area borders existing designated sites for protected species and habitats, and lies adjacent to a wide array of coastal features including sheltered bays, estuaries, coastal cliffs and sea caves, several of which are located within protected sites. Bottlenose Dolphin occurs within the site in all seasons and the area comprises a key habitat for the species both regionally and within Irish waters as a whole. The NPWS citation notes that the SAC may contain a minimum of 123 dolphins with possibly up to individuals or more occurring within the site as a whole. The SAC is known to be used for a variety of activities including foraging and resting, and adults closely accompanying calves are commonly observed in summer and autumn months. Significant structural linkages have been established between groups of dolphins utilising various coastal habitats within the site while a high proportion of individuals have been shown to range freely within coastal waters. Coastal observations indicate widespread use of the area by individual groups of dolphins. Hence individuals may also traverse the area of the proposed marine works. According to O Cadhla et al., 2004, and Berrow 2002 Bottlenose dolphins are often associated with coastal areas, but an offshore population is also considered to be continuously distributed along Ireland s Atlantic Margin, to the continental slope and out to oceanic waters. Western Ireland is home to at least one resident bottlenose dolphin population, centred on the Shannon Estuary. The species is known to breed in Irish Waters and is known to be present in these waters year round. Peak sightings in the waters west of Mayo tend to occur during summer months however. During 2012 Marine Mammal Observers were present in the Corrib Offshore Gas Field during the OBC seismic survey programme. A number of marine mammal sightings were made during these works from the seismic source vessel Malene Ostervald. These sightings included 19 Bottlenose dolphins, which were seen twice as a single group on 17 th June. The group comprised 16 adult animals and 3 juveniles. They were observed to be foraging and were very active, breaching and tail slapping. The group broke into two, and a smaller group of 6 individuals approached the vessel and bow rode briefly RSK/He/P/P40036/44/NIS for OBC rev00 12

17 before rejoining the main group. At the time of the observation the air guns were in the process of being deployed, but were not shooting seismic. The total period of marine mammal observations in the Corrib Field in 2012 was approximately 786 hours. 4.1 CONSERVATION OBJECTIVES According to the EU Habitats Directive, favourable conservation status of a species is achieved when: population data on the species concerned indicate that it is maintaining itself the natural range of the species is neither being reduced or likely to be reduced for the foreseeable future, and there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis. The Minister of Arts, Heritage and the Gaeltacht (DAHG) intends to designate the West Connacht Coast SAC, and as such the conservation objectives for this proposed site have not been published. However the above bullet points indicate generic criteria for favorable conservation status. RSK/He/P/P40036/44/NIS for OBC rev00 13

18 5 ASSESSMENT OF LIKELY EFFECTS 5.1 CONSIDERATION OF SIGNIFICANCE In terms of significance, the NPWS Guidance (2010 Rev) uses an EC definition as follows: any element of a plan or project that has the potential to affect the conservation objectives of a Natura 2000 site, including its structure and function, should be considered significant (EC, 2006). In general, significance indicators might include: impact on Annex I habitat (including loss or reduction in size - percentage relative to the overall area of the habitat in the Natura site; impairment of function) fragmentation of habitat or population (depending upon the duration or permanence) disturbance (noise, light etc. - distance, duration) effect on species populations (direct or indirect damage to size, breeding patterns etc) changes in water quality. To summarise the significance issue, it is useful to quote from Morris (2008) who describes significance in the context of the Habitats Directive as follows: Within the Habitats Regulations, significance is quite different. It is used as a coarse filter and the test is a question over the possibility that there will be a significant effect on a key receptor that determines the conservation status of a European site. Thus, determining whether there will be a likely significant effect does not imply that there will be such an effect or even that such an effect is more likely than not; it simply flags the need to test the issues and then make a judgement of the pathways and mechanisms imposed by a project on the designated wildlife interest. This test best equates to the screening and scoping opinions sought for an EIA but is confined to the Natura 2000 and Ramsar interest rather than wider environmental or nature conservation issues. In order to assess the likely impacts and ascertain whether a significant impact on the integrity of the Natura site(s) is likely to occur as a result of the proposed development, should the appropriate assessment process be deemed to apply, it is necessary to consider what constitutes the integrity of a Site as referred to in Article 6(3). The document Managing Natura 2000 Sites, The provisions of Article 6 of the Habitats Directive 92/43/EEC (2000) gives clear guidance in this regard and states: The integrity of the site involves its ecological functions. The decision as to whether it is adversely affected should focus on and be limited to the site s conservation objectives. Integrity has been discussed and defined in various ways in guidance documentation and the literature. For example, Treweek (1999) discusses biological integrity and ecosystem health, and refers to three generally accepted criteria: systematic indicators of ecosystem functional and structural integrity; ecological sustainability or resilience (relating to the ability of a system to withstand natural or anthropogenic stresses); and absence of detectable symptoms of ecosystem disease or stress. A similar, but less academic, approach is adopted by the various guidance documents with a number of definitions proposed. RSK/He/P/P40036/44/NIS for OBC rev00 14

19 5.2 IMPACTS OF NOISE ON MARINE FAUNA One of the most important environmental concerns related to seismic survey activities are the potential effects of the sound waves produced by the acoustic source array on different marine biota, in particular marine mammals and other animals protected under Annex IV of the EU Habitats Directive (Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora). The propagation of low frequency sound in the sea is efficient, with little loss due to attenuation (i.e. due to absorption and scattering). The degree of attenuation is dependent on the propagation conditions (propagation is impacted by varying pressure, temperature and salinity). Close to the airgun array, spherical spreading loss (the reduction in intensity caused by the spreading of waves into an ever increasing space) results in signal intensity dropping quickly. This loss is around 6dB per doubling of distance. In good propagation conditions, the signal may be above the background level for more than 100 km; in poor propagation conditions, it may reach background level within a few tens of kilometres (McCauley, 1994). The sound waves that travel laterally will continue until they meet an object or they are dissipated by normal decay of the signal. Despite these factors, in-water sound travels a long distance and some low frequency sound waves from the seismic source may be detectable at tens of kilometres from the array. Nevertheless, the intensity of the sound waves does decay exponentially and although low-level signals travel for long distances, the higher amplitude waves lose much of their energy very close to the airgun array. An animal s ability to detect sounds produced by anthropogenic activities depends on the amount of natural ambient or background sound. Wind, precipitation, vessel traffic, and biological sources all contribute to ambient sound. Ambient sound is highly variable on oceanic continental shelves and this may result in considerable variability in the range at which marine animals can detect anthropogenic sounds. Table 5.1 shows various anthropogenic sources and received levels of sound in the marine environment. Shipping is the most dominant source of sound in the world s oceans in the frequency range of 5 to a few hundred Hertz (NRC, 2005). Activity High resolution geophysical survey; pingers, side-scan, echosounder Low resolution geophysical seismic survey; Seismic air gun Table 5-1: Sound sources from various maritime activities (Source data: adapted from: Evans & Nice, 1996; Richardson et al., 1995, in IOSEA2). Frequency range (khz) 10 to to 0.2 b 248 Average source Estimated received level at different ranges (km) by spherical spreading a level (db re 1μPa-m) 0.1 km 1 km 10 km 100 km < c 144 c 118 c 102 d Production drilling Jack-up drilling rig to to to to 66 <41 0 Semi-submersible to to to to to 85 6 to 10 RSK/He/P/P40036/44/NIS for OBC rev00 15

20 rig Drill ship 0.01 to to to to to to 30 Large vessel merchant to to to to to 104 <29 Military vessel to to to to 117 Super tanker 0.02 to to to to to to to 71 a Spherical spreading is calculated here using the formula presented in IOSEA2. b Seismic surveys produce occasional sounds with frequencies of 1 to 22 khz (Evans, 1998) c Actual measurements in St George s Channel, Irish Sea. d Extrapolated figure as presented by Evans & Nice, There are various potential effects of exposure to sound from seismic and other sources that can be characterised as pathological, physiological or behavioural. One way of estimating the level of effect on marine mammals is to consider species specific hearing audiograms, and to identify areas where the anthropogenic sound source level frequencies overlap with them. A calculated audiogram for the Bottlenose dolphin is presented in Figure 5-1. As noted in Table 5-1, the majority of the acoustic energy from the source for the seismic survey will be in the range 8-200Hz, Bottlenose dolphins can hear sound in part of that frequency range, but the pressure level of the sound needs to be at least 110dB to be perceived at all. Figure 5-1: Bottlenose dolphin hearing threshold audiogram RSK/He/P/P40036/44/NIS for OBC rev00 16

21 In the following sections, the potential impacts of seismic and other offshore construction sounds on Annex IV marine mammals species are considered. 5.3 IMPACTS OF SEISMIC SOURCE SOUND ON ANNEX IV MARINE MAMMALS Baleen whales are reported to have hearing sensitivity ranges between 10 Hz to 10 khz, with greatest sensitivities usually below 1 khz (Evans, 1998). This hearing range overlaps with the low frequency sounds produced by seismic surveys, which may mask long distance communication between whales over significant distances and prevent the detection of other faint sounds (Evans & Nice, 1996). Toothed whales rely on sound for echolocation, foraging and communication. Their auditory sensitivities range from 75 Hz to 150 khz, with greatest sensitivities around 20 khz. Their hearing is therefore most sensitive outside the peak energy range (0 to 120 Hz) of seismic air guns. However, air gun arrays can occasionally produce significant sound at frequencies of 1 to 20 khz. Southall et al. (2007) carried out an extensive review of the available literature and formulated scientific recommendations for marine mammal exposure criteria. For low frequency hearing cetaceans (auditory sensitivity range estimated at 7 Hz to 22 khz) and mid frequency hearing cetaceans (auditory sensitivity range estimated at 150 Hz to 160 khz), the sound exposure level (SEL) for injury was set at 198 db re 1μPa 2-s (Mmf 4 ), for peak sound pressure level this level increased to 230 db re 1μPa 2-s. It should be stressed that no marine mammal mortality or damage to tissue has been documented for exposure to air guns during seismic surveys and that the exposure level for injury is a theoretical value extrapolated from experimental data. It is recognised that many variables affect the nature and extent of responses to a particular stimulus. Such variables may include the recent experience of marine mammals with the sound stimulus, and their current activity (e.g. feeding vs. migrating). Observations undertaken during 201 seismic surveys in UK and adjacent waters have been analysed to examine effects on cetaceans (Stone & Tasker, 2006). Sighting rates, distance from airguns and orientation to the source were compared for periods when air guns were active and when they were silent. It was suggested that the different taxonomic groups of cetaceans may adopt different strategies in response to acoustic disturbance from seismic surveys. Some small odontocetes (toothed whales) move out of the immediate area, while the slower moving mysticetes (baleen whales) orient away from the vessel and increase their distance from the source but may not move away from the area completely. As shown in Figure 5.1, cetaceans tended to remain more than 500 m from the inactive seismic array and generally moved even further away when a seismic array was operating. This presumably reduces the sound exposure levels on the animal. 4 Frequency weighting for mid-frequency cetaceans (most Odontocetes) RSK/He/P/P40036/44/NIS for OBC rev00 17

22 Figure 5-2: Median closest distance of approach of cetaceans to large volume airgun arrays in relation to airgun activity (from Stone and Tasker, 2006) Some of the larger odontocetes, such as sperm whales and beaked whales, are deep diving species, which makes them potentially more susceptible to the impacts of underwater sound. Deep diving species are exposed to higher sound levels than animals near the surface, including the zone directly beneath the air gun array in which the sound is most focused (Gordon et al., 2004). Deep divers are also potentially more susceptible to physiological effects, as they stay at depth for relatively long periods of time, and operate on the extremes of their energy and oxygen use during their dives. Observations of responses of sperm whales to seismic surveys are contradictory however, ranging from no significant difference (e.g. Stone, 2003; Swift, 1998) to interrupted vocalisations at 370 km from a seismic air gun array (Bowles et al., 1994) Impacts on Marine Mammals in the Corrib Field It should be noted that the risk assessment (RSK, 2013a) focused on the hazards and risks posed to Annex IV species in and close to the Corrib Field during the OBC survey, and was not species specific. Furthermore, the assessment was based on a number of assumptions that need to be considered when interpreting the risk assessment: Some Annex IV species are easier / more difficult to detect by the onboard MMO. In the case of cetaceans, smaller species such as the harbour porpoise can be difficult to detect in sea states of more than 2 on the Beaufort scale. It is likely that some species will not be in the area of the Corrib Field during at all times throughout the OBS survey. RSK/He/P/P40036/44/NIS for OBC rev00 18

23 The assumption has been made that some species will leave the area during seismic activity, and as a result of the soft start approach. Some species, including Bottlenose dolphin, have been known to approach seismic vessels during seismic activity. In the majority of cases however evidence has shown that typical behavioural responses are avoidance (Southall et al., (2007). The assessment is based on the NWPS guidelines covered in the Code of Practice for the Protection of Marine Mammals during Acoustic Seafloor Surveys in Irish Waters (DEHLG, 2007) for soft start/pre soft start procedures and estimated safe distances. There is the possibility that the time and safe distance given may not be sufficient for a particular species, or an individual animal, as the guidelines cover all Annex IV species. The risk assessment concluded that impacts to marine mammals in the Corrib Field (including Bottlenose dolphins) would be minor. Section provides a brief assessment of the effects of the seismic survey work on bottlenose dolphins, which may be present in the Corrib Field. 5.4 IMPACTS ON NATURA 2000 SITES This section summarises the aspects, impacts, mitigation measures, predicted impacts, and significance of the predicted impacts from the proposed survey on bottlenose dolphins in the SAC, and individuals which have fidelity with the SAC and may be present in and around the Corrib Field periodically. The evaluation of the significance of impacts on bottlenose dolphin in the context of the proposed West Connacht Coast SAC is summarised in Table 5.2. The relative significance of a predicted impact is summarised by applying a keyword from a scale from Major through to Negligible (or Beneficial) as defined in Table 3.3. The evaluation considers the vulnerability, temporal sensitivity and recoverability of bottlenose dolphins and the geographical extent of the effect (See Section 3) Discussion of impacts on habitats in the West Connacht Coast SAC The proposal to designate the West Connacht Coast is dependent on the species present there rather than the habitats, and while the habitats present sustain the qualifying species, they are not considered to be qualifying features under Annex I of the Habitats Directive. It should be noted that the acoustic source situated a minimum of 47.5 km from the SAC would not be anticipated to have an impact on the SAC habitats, irrespective of whether or not they are of qualifying interest for the SAC Discussion of impacts on qualifying species for the West Connacht Coast SAC Bottlenose Dolphin is the only species of qualifying interest for the SAC. The seismic survey works could affect Bottlenose dolphins which have fidelity to the SAC either whilst they are within or outside of the designated area. Bottlenose dolphins would experience the highest noise levels if they were in close proximity to the sound source i.e. they were present in the Corrib Field. They could also perceive the sound from the survey work whilst they were located in the SAC, however noise levels will have reduced considerably in magnitude by the time they reach the SAC. RSK/He/P/P40036/44/NIS for OBC rev00 19

24 Impacts in the Corrib field According to Southall et al. (2007) mid-frequency cetaceans, which include Bottlenose dolphins have an estimated hearing range within the auditory bandwidth of 150Hz to 160 khz, and its criteria for injury is estimated at a sound pressure of 230 dbpeak re.1μpa (flat) and 198 db re.1μpa 2-s (Mmf). The hearing sensitivity of the high and mid frequency cetaceans (including bottlenose dolphins) is poor at the frequencies of the bulk of the acoustic energy from the seismic source (see Figure 5-1 for bottlenose dolphin). The example injury criteria contained within Southall et al. (2007) that have been adopted by the UK Joint Nature Conservation Committee (JNCC) as a suitable criteria to determine what constitutes an injury offence in accordance with Article 12 of the Habitats Directive is listed above. Overall, the majority of noise energy produced from the proposed OBC seismic survey works in water is in the range of Hz (Table 5-1) and as such is at a frequency at which the auditory capabilities of bottlenose dolphins are becoming less sensitive (see Figure 5-1). The average predicted noise output from the proposed marine works is estimated to be in the region of 250dB at a distance of one metre, and as such any animal in the immediate vicinity of the air guns is likely to suffer injury. It is for that reason that the survey operations incorporate the Code of Conduct defined by the NPWS (NPWS, 2007) which includes the employment of marine mammal observers to ensure that marine mammals are not present in the vicinity of the seismic source as it begins operation (it is assumed that if marine mammals approach a seismic source that is already active, that they accept that the noise is not harmful). A soft start approach is also used, whereby when the acoustic source is activated, it begins at a low intensity, building up slowly to its survey operational level. As noted above Bottlenose dolphins were observed in the Corrib Field during OBC work carried out in 2012, however, whilst the size of the group sighted was quite large, it was sighted only twice during 768 hours of observations. It may well be the case that the Bottlenose dolphins seen in the Corrib Field are part of the population with fidelity to the West Connacht Coast SAC. The above noted mitigation measures and the low frequency of observations of Bottlenose dolphins in the Corrib Field result indicate that the effects on individuals in the vicinity of the Corrib Field will be Minor. Other activities which take place as part of the seismic survey include mobilization of the vessel from port to the Corrib Field, deployment and retrieval of cables to/from the seabed and routine vessel discharges. The following paragraphs cover the impacts from these planned activities in the Corrib Field. Whilst in transit from the mobilization port (Killybegs) to the Corrib Field, engine noise will be introduced into the marine environment. This noise may disturb bottlenose dolphins in close proximity to the vessel itself, but will not cause injury to them. Table 5-1 presents typical vessel noise source levels and it can be seen that these are well below the auditory injury threshold (if engine noise for a large merchant vessel at 10km distance is used estimated noise levels are db). There is also a potential for collision of bottlenose dolphins with the vessel as it transits, though this is considered extremely unlikely, as is the potential for the presence of the vessel traumatizing bottlenose dolphins. The impacts from the vessel transit are therefore considered Minor. During the survey there will be frequent removal and replacement of seabed cables as the survey moves across the Field. Entanglement of marine mammals with these cables RSK/He/P/P40036/44/NIS for OBC rev00 20