Physical environment Table of Contents 8 PHYSICAL ENVIRONMENT 8-4 8.1 Introduction 8-4 8.2 Legislative context and relevant guidance 8-5 8.3 Scoping and consultation 8-6 8.4 Baseline description 8-6 8.4.1 Introduction 8-6 8.4.2 Designated features 8-9 8.4.3 Bathymetry 8-11 8.4.4 Wind 8-11 8.4.5 Wave 8-13 8.4.6 Current 8-13 8.4.7 Water levels 8-15 8.4.8 Seabed sediment and geology 8-15 8.4.9 Coastal description 8-19 8.4.10 Water quality 8-19 8.4.11 Data gaps and uncertainties 8-21 8.5 Impact assessment 8-21 8.5.1 Overview 8-21 8.5.2 Assessment criteria 8-21 8.5.3 Design Envelope 8-23 8.6 Impacts during construction and installation 8-23 8.6.1 Effects on the coast at the cable landfall 8-23 8.6.2 Effects on the Scottish Water outfall 8-24 8.7 Impacts during operation and maintenance 8-24 8.7.1 Effects on the coast at the cable landfall 8-24 8.7.2 Introduction of scour within the Pilot Park 8-25 8.8 Potential variances in environmental impacts (based on Design Envelope) 8-25 8.9 Cumulative and in-combination impacts 8-25 8.9.1 Introduction 8-25 8.9.2 Potential cumulative and in-combination impacts during construction and installation, operation and maintenance 8-26 8.9.3 Mitigation requirements for potential cumulative and in-combination impacts 8-26 8.10 Monitoring 8-26 8.11 References 8-26 Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-002 8-3 8 PHYSICAL ENVIRONMENT Characterisation of the existing physical environment and sediment processes is based on both existing and site- specific survey data. The turbine deployment area and majority of the export cable corridor are characterised by thick sediment cover. The deep water at the turbine deployment area means that wave action is unlikely to influence scour. The coast at the cable landfall is comprised of irregular basement rock, with mobile cobbles and boulders lying towards the west of the potential landfall site. The base case for cable landfall is installation via HDD; however the option of cable installation via a surface trench has been assessed as this would result in greater impacts compared with the HDD option. Through scoping, it was identified that the physical environment may be affected as a result of: • Effects on the coast at the export cable landfall; • Effects on the Scottish Water outfall; and • Introduction of scour within the Pilot Park. The coastal environment at the cable landfall is considered to be tolerable to change, due to its irregular rocky nature, and mobile cobbles and boulders, therefore the sensitivity of the rocky shore and seabed is considered to be low. Any changes are expected to be of short duration and minor magnitude. The beach at the cable landfall has a seawall for shore protection and the Buchanhaven combined sewer overflow (CSO) discharge pipe is located within the cable landfall footprint. This existing infrastructure could be impacted should the cable be installed across the beach (rather than via HDD). HSL will ensure any necessary measures are taken to protect the seawall and outfall during cable installation. There is potential for some limited areas of scour around suction anchors and if required scour protection will be installed over an area of not more than 15 m from the edge of each anchor. The impacts of this are assessed as relevant in other chapters of the ES e.g. benthic ecology. 8.1 Introduction This section assesses the impacts of the Project on the physical environment. A number of different specialists have contributed to this assessment: > MMT – seabed survey, video footage analysis, biotope mapping, seabed survey reporting; > GEO – geotechnical survey, soil analysis, survey reporting; > Statoil – metocean design basis; and > Xodus – landfall site walkover, geotechnical evaluation, geotechnical desk study report, phase 1 intertidal survey report, baseline description, impact assessment and ES chapter write up. Table 8-1 provides a list of the supporting studies which relate to the physical environment impact assessment. All supporting studies are provided on the accompanying CD. Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-002 8-4 Table 8-1 Supporting studies Details of study Geophysical survey report (MMT, 2013a) Environmental survey report (MMT, 2013b) Geotechnical survey report (GEO, 2014) Geotechnical desk study report (Xodus, 2013a) Landfall site walkover report (Xodus, 2013b) Phase 1 intertidal survey report (Xodus, 2013c) Buchan Deep metocean design basis (Statoil, 2014) The focus of this physical environment assessment is to assess potential impacts on physical processes and sediment dynamics in the proposed turbine deployment area, the export cable route and cable landfall site as shown in Figure 8-1. The following areas are referred to in this impact assessment: > Project area (see Figure 1-2), which comprises: o Proposed offshore turbine deployment area: and o Export cable corridor and landfall. > Study area – area shown on Figure 8-1, which incorporates the proposed turbine deployment area and the export cable corridor. None of the impacts in this chapter are predicted to extend beyond the Project area, as impacts to currents, waves and sediment transport which often create the need for a wider study area were deemed negligible during scoping. > Survey area – area outlined in Figure 8-1, which incorporates the proposed turbine deployment area and the export cable corridor. 8.2 Legislative context and relevant guidance The EIA Regulations stipulate a requirement to assess the impacts of a project on water quality and sediment. The Water Environment and Water Services (Scotland) Act 2003, which implements the Water Framework Directive (WFD), should also be considered, with respect to River Basin Management Plans (RBMP) coastal water bodies. Information on current WFD RBMP status is summarised from the SEPA River Basin Management Plan information sheets (SEPA, 2009). There are no specific legislative controls relevant to the scope of the physical environment impact assessment. However there is specific guidance relevant in addition to the EIA guidance published by Marine Scotland and SNH: > Offshore Wind Farms. Guidance Note for Environmental Impact Assessment in Respect of FEPA and CPA Requirements. (Cefas, 2004); > Guidelines for data acquisition to support marine environmental assessments of offshore renewable energy projects (Cefas, 2012); > Assessment of the Significance of Changes to the Inshore Wave Regime as a consequence of an Offshore Wind Array (Cefas, 2005); > Coastal Process Modelling for Offshore Windfarm Environmental Impact Assessment (COWRIE, 2009); > Review of Cabling Techniques and Environmental Effects applicable to the Offshore Windfarm Industry (BERR 2008); and Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-002 8-5 > Potential effects of offshore wind developments on coastal processes. (ABPmer and Metoc for DTI (now DECC) 2002). The Cefas guidelines highlight that direct impacts on hydrodynamics and sediment dynamics should be considered, along with secondary effects including water and benthic ecology (Chapter 9). 8.3 Scoping and consultation The bullets below summarise the key issues raised in the Scoping Opinion relevant to the physical environment impact assessment: > Concerns on impacts to the adjacent water body, so the ES should assess the significance of such alterations and discuss the implications of these with respect to shoreline and seabed morphology, and wider ecosystem health in line with River Basin Management Plan (RBMP) objectives. > Concern regarding the cable route and the Southern Trench MPA search area. This will need to be considered and effective mitigation proposed if significant impacts are anticipated. > Concern regarding changes to local bathymetry arising from open trenches or rock armour can impact the quality of the wave resource available for surfing. Table 8-2 summarises all consultation activities carried out relevant to the physical environment. Table 8-2 Consultation activities undertaken in relation to the physical environment Date Stakeholder Consultation undertaken May 2013 Marine Scotland (MS-LOT and Pre-scoping meeting including discussion on proposed scope of marine Marine Scotland Science) and physical environment impact assessment statutory consultees October 2013 Marine Scotland, statutory Request for EIA Scoping Opinion for Marine Scotland and statutory consultees and non-statutory consultees and request for comment from non-statutory consultees consultees (including SEPA, Surfers Against Sewage, and the Scottish Surfing Federation) January 2014 Marine Scotland, JNCC and Submission of the MMT environmental survey report for comment SNH February 2014 Marine Scotland Report on EIA progress including feedback on MMT Environmental Survey Report March 2014 Marine Scotland, statutory Receipt of response to Scoping Opinion, including comments on the consultees and non-statutory MMT environmental survey report consultees May 2014 Marine Scotland, SNH, JNCC Meeting at which Statoil response to comments from JNCC, SNH and Marine Scotland Science were presented May 2014 Local stakeholders Public event in Peterhead to collate information opinions on EIA scope 8.4 Baseline description 8.4.1 Introduction As part of the desk based study for the assessment of impacts in relation to the physical environment, baseline data and information have also been collected from the following sources: > Barne, J.H., Robson, C.F., Kaznowska, S.S., Doody, J.P. & Davidson, N.C. (1996). Coasts and seas of the United Kingdom Region 3 North-east Scotland: Cape Wrath to St. Cyrus. JNCC Coastal Directories Series, Peterborough. Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-002 8-6 > Ramsay, D.L. & Brampton, A.H.