OTHER SEA USERS
Table of Contents
17 OTHER SEA USERS 17-4
17.1 Introduction 17-4 17.2 Scoping and consultation 17-4 17.3 Baseline description 17-5 17.3.1 Introduction 17-5 17.3.2 Oil and gas activities 17-5 17.3.3 Submarine cables 17-6 17.3.4 Unexploded ordnance (UXO) 17-8 17.3.5 Disposal sites 17-8 17.3.6 Data gaps and uncertainties 17-8 17.4 Impact assessment 17-8 17.4.1 Overview 17-8 17.4.2 Proximity to the BP Forties Pipeline 17-9 17.4.3 Assessment criteria 17-10 17.4.4 Design Envelope 17-10 17.5 Impacts during construction and installation 17-11 17.5.1 Impacts on cables 17-11 17.5.2 Inadvertent detonation with consequent damage to equipment or injury to personnel from interaction with UXO 17-12 17.6 Impacts during operation and maintenance 17-12 17.6.1 Impacts on other cables 17-12 17.6.2 Impacts from proposed cables 17-13 17.6.3 Inadvertent detonation with consequent damage to equipment or injury to personnel from interaction with UXO 17-13 17.7 Potential variances in environmental impacts (based on Design Envelope) 17-14 17.8 Cumulative and in-combination impacts 17-14 17.8.1 Mitigation requirements for potential cumulative and in-combination impacts 17-14 17.9 Monitoring 17-15 17.10 References 17-15
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 iii
17 OTHER SEA USERS
The BP Forties crude oil pipeline system which transports 40% of the UK North Sea oil production, passes through the Agreement for Lease (AfL) area, 1 km to the south of the proposed turbine deployment area. There are several existing cables in the vicinity of the proposed turbine deployment area and export cable corridor, including one cable along the export cable route for which it has not been possible to identify the owner. Two active and one inactive at sea disposal sites are located adjacent to the export cable corridor close to shore. An explosive ordnance legacy from the two world wars and modern military exercises has potential to contaminate the Project area. The Project will have crossing agreements in place with other cable operators to ensure that no significant impacts result from the installation and operation the Project and procedures will be in place to minimise the risk of inadvertent detonation of unexploded ordinance. Discussions are ongoing with BP to ensure minimised risk to the BP asset.
17.1 Introduction Other chapters within this ES assess the impacts of the main sea user groups including shipping and navigation (Chapter 15) and commercial fisheries (Chapter 14). This section assesses the impact of the Project on other users of the sea including pipelines, at sea disposal sites, cables and unexploded ordnance (UXO). A number of different specialists have contributed to this assessment:
> Ordtek - Unexploded Ordnance (UXO) desk study and risk assessment (Ordtek, 2014); and
> Xodus - baseline description, impact assessment and ES chapter write up.
Table 17-1 provides details of the supporting study which relates to the other sea users impact assessment. The study is provided on the accompanying CD.
Table 17-1 Supporting studies
Details of study Unexploded ordnance desk based study with risk assessment (Ordtek, 2014)
The following areas are referred to in this impact assessment:
> Project area (see Figure 1-2 in the introduction), which comprises:
o Proposed offshore turbine deployment area: and o Export cable corridor and landfall. 17.2 Scoping and consultation The bullets below summarise the key issues raised in the Scoping Opinion relevant to the other sea users impact assessment:
> Proximity of the Hywind Scotland Park Project to the BP assets;
o Preference of use of permanent moorings to prevent drag across the seabed;
o Better understanding of the direct risks of catastrophic damage to BP assets;
o Assurance that maintenance and inspection of existing assets and infrastructure will not be hindered as a result of the Project; and
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-4
o Insurance that a full and detailed survey will be undertaken prior to construction to ensure existing infrastructure is safeguarded.
> Assessment of in-combination and cumulative impacts in relation to other planned projects to be undertaken.
Table 17-2 summarises all consultation activities carried out relevant to other sea users.
Table 17-2 Consultation activities undertaken in relation to other sea users
Date Stakeholder Consultation undertaken May 2013 Marine Scotland (MS-LOT and Marine Pre-scoping meeting including discussion on Scotland Science) and statutory proposed scope of other sea users impact consultees assessment October 2013 Marine Scotland, statutory consultees Submission of EIA Scoping Report – request for EIA and non- statutory consultees Scoping Opinion from Marine Scotland and statutory consultees and request for comment from non- statutory consultees March 2014 Marine Scotland, statutory consultees Receipt of Scoping Opinion and non- statutory consultees May 2014 Local stakeholders Public event in Peterhead to collate information / opinions on EIA scope Various BP Series of meetings with to discuss and present the results of work associated with potential risks to the BP Forties pipelines Various Marine Scotland, Crown Estate, BT and Meetings and e mail communication in order to various survey companies that have establish ownership of the unknown cables and agree worked in this area of the North Sea procedures for handling of cables that were identified in the geophysical survey, but ownership cannot be traced
17.3 Baseline description
17.3.1 Introduction The baseline description of other sea users in the Project area has been compiled from available published data, supplemented by Project specific geophysical and geotechnical surveys.
17.3.2 Oil and gas activities The Project lies within oil and gas licensing Quadrant 19. Oil and gas activity is relatively low in this area of the North Sea, and few blocks within Quadrant 19 are currently licensed (Table 17-3). However, the BP Forties pipeline system that passes through the AfL area does transport 40% of the UK North Sea oil production. The closest licensed areas to the Agreement for Lease (AfL) area are Blocks 19/4, 19/5 and 19/10 (Figure 17-1). Blocks 19/2, 19/3 and part of 19/10 were in the previous 27th licensing round application process (DECC, 2014). An additional 24 Blocks within Quadrant 19 were recently on offer as part of the 28th licensing round (DECC, 2014). At the time of writing, these blocks were yet to be awarded.
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-5
Table 17-3 Currently licensed Blocks within Quadrat 19 (UK Oil and Gas Data, 2014)
Quadrant/Block Licence round Current licence operator Licence expiry date 19/1 26 Maersk Oil North Sea UK Limited 1 February 2038 19/2 27 Encounter Oil Limited 20 December 2039 19/3 27 Encounter Oil Limited 20 December 2039 19/4 26 Nexen Petroleum U.K. Limited 1 February 2038 19/5 and 19/5a 16 Nexen Petroleum U.K. Limited 25 July 2031 19/5b 26 Nexen Petroleum U.K. Limited 1 February 2038 19/10 27 Nexen Petroleum U.K. Limited 20 December 2039 19/10a 18 Nexen Petroleum U.K. Limited 23 December 2034
A total of 11 wells have been drilled in Quadrant 19, the majority being dry holes. The closest oil and gas activity to the Project is the Nexen operated Buzzard oil field, which is located in Blocks 19/5, 19/10, 20/1 and 20/6 approximately 40 km to the north west of the AfL area (UK Oil and Gas Data, 2014).
The HSL AfL area is split into northern and southern parts by the Forties to Cruden Bay pipeline system (crude oil) which passes through the area from the northeast to the southwest, shown in Figure 17-1. The pipeline system is located to the south of the turbine deployment area and the northern AfL and is located approximately 1 km from the proposed turbine deployment area. These pipelines are operated by BP and come ashore at Cruden Bay to connect the Cruden Bay Pressure Relief and Pumping Station, 35 km north of Aberdeen. Onshore pipelines carry the liquids to separation and processing facilities at Kinneil, Grangemouth and Firth Forth.
To the north of Peterhead, St Fergus is a landing point for numerous offshore pipelines, the closest of which is approximately 5 km from the cable route corridor and, further offshore, from the AfL area (Figure 17-1).
17.3.3 Submarine cables There are several existing submarine cables in the vicinity of the Project. These include the active CNS fibre optic cable, owned by BP, which runs parallel to the BP Forties to Cruden pipelines. The cable is located approximately 1 km from the proposed turbine deployment area. A possible cable ‘unknown cable 1’ was 5.8 km to the north east of the turbine deployment area at its closest point (Figure 17-1). Ownership of the possible cable could not be traced.
Figure 17-1 shows three cables passing through the proposed offshore turbine deployment area. The geophysical survey undertaken by MMT (2013) found no trace of the charted disused cable and concluded that it is likely that it may be the BT Aberdeen – Bergen cable. An additional cable ‘unknown cable 2’ was also found running east to west through the proposed offshore turbine deployment area. Ownership of the possible cable could not be traced.
Two subsea cables pass through the northwest edge of the export cable route corridor to the north of Peterhead. These cables (Peterhead to Alexandrovsk (installed 1914) and Peterhead to Egersund (1924)) have been identified as existing assets by The Crown Estate (Figure 17-1). Both cables are inactive.
The route for the proposed NorthConnect High Voltage Direct Current (HVDC) interconnector cable is from Peterhead in Scotland to Sima and Samnanger in Norway (NorthConnect, 2014). The proposed cable route is approximately 600 km long and crosses the export cable route corridor (Figure 17-1).
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-6
Figure 17-1 Other sea users in the vicinity of the project
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-7
17.3.4 Unexploded ordnance (UXO) Ordtek (2013) conducted a desk based study and risk assessment to assess the potential risk to the Project from UXOs. The report identified that the presence of dump sites, official and unofficial, and the explosive ordnance legacy from two World Wars and modern military exercises have the potential to contaminate the Project area with UXOs (Ordtek, 2013). The UXO threat items most likely to be encountered are German WWI and British WWII moored mines that have sunk to the seabed. Possible charge weights vary from 50 kg to 350 kg, but are most likely to be between 90 kg and 227 kg. The typical diameter of the buoyant mines likely to be present is 0.84 to 1.01 m.
17.3.5 Disposal sites There are two open (‘North Buchan Ness’ and ‘Peterhead’) and one closed disposal site (‘middle Buchan Ness’) adjacent to the export cable corridor (Figure 17-1). Over the past 13 years, the two open sites have been used for the deposition of dredged harbour material from Peterhead and / or Boddam Harbour (Walker pers. comm. Marine Scotland, 2013). Details of the chemical composition of the sediment at these sites are provided in Chapter 9 – benthic and intertidal ecology.
17.3.6 Data gaps and uncertainties A robust baseline is available to characterise the other sea users in and surrounding the proposed Project and inform the impact assessment. The only minor data gap is the inability to trace the owners of two of the unused cables; however, this does not compromise the ability to undertake a robust impact assessment.
17.4 Impact assessment
17.4.1 Overview Following establishment of the baseline conditions to the Project area, and an understanding of the Project activities it is possible to assess the potential impacts from the Project. The range of impacts that have been considered is based on impacts identified during EIA Scoping and any further potential impacts that have been highlighted as the EIA has progressed. The impacts assessed are summarised below. It should be noted that not all impacts will be relevant to all phases of the Project.
> Impacts on pipelines;
> Impacts on cables (existing and proposed); and
> Inadvertent detonation of unidentified unexploded ordnance.
The following impacts were scoped out of the assessment during EIA scoping:
> Restriction on the expansion potential of at sea disposal sites located adjacent to the export cable corridor; and
> Interference with military practice and exercise areas.
The following specialist studies have been completed to inform the assessment of impacts on other sea users:
> An unexploded ordnance desk based study with risk assessment was undertaken by Ordtek (2014). The study carried out an in-depth historical search into records in order to assess the potential risk to the project from UXO.
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-8
17.4.2 Proximity to the BP Forties Pipeline The Project will be located in the northern sector of the AfL area, north of the BP Forties pipeline system. Cable crossing of the pipeline is therefore not needed. The chosen location of the turbine deployment area is based on environmental, geophysical and geotechnical studies performed by Statoil. The closest anchor will be placed a minimum of 1 km away from the pipeline, while the closest turbine will be approximately 1.5 km away.
During scoping, BP raised concerns about the potential risk to the BP Forties pipeline system. Several of the concerns raised in the Scoping Opinion were related to potential crossing of the BP assets by inter-array cables and the export cable. This is no longer a concern, since the WTG Units will be located north of the pipeline. However, due to the proximity to the pipeline, BP has been fully consulted during the conceptual design and FEED (Front End Engineering and Design) phase, and will be further consulted during the detailed design phase. There have been several meetings between BP and Statoil to discuss how to ensure minimised risk to the BP assets1.
The main concern in relation to the pipelines is the design, fabrication, installation and operation of the mooring system, the potential risk of mooring line failure, and the potential consequences for the pipelines. The mooring system is designed according to the DNV standard for floating wind turbines2, with the purpose of designing a safe, redundant and robust system. A 3-line mooring configuration has been chosen, and designed in such a way that in the case of a mooring line failure, the remaining lines will keep the WTG Unit in place. Even in the case of a second line failure, the third line will be able to keep the WTG Unit in place. The mooring system is also designed with suction anchors rather than fluke anchors, and with pure chain rather than using clump weights, both of which reduces the risk of damage in case of mooring line failure.
DNV GL has performed a risk assessment of the probability of mooring line failures and the potential implications for the BP pipeline system. Mooring lines dragging over the pipelines will cause no significant damage to the pipelines itself. The only possible major damage to the pipelines is considered to occur if they were to be hit by the Hywind substructure. Such an event requires that all three mooring lines are lost, and the installation drifts south, and sinks and hits the pipelines. The probability of such an event is found to be very unlikely3.
There is limited experience with floating wind turbines; currently only a handful of demonstration projects have been installed and operated, whereas the Hywind demo off the west coast of Norway is the one with the longest operational time of 5 years. Due to lack of statistics from the floating wind industry, statistics from the oil & gas industry have been utilised for the DNV GL assessment. Unlike typical oil and gas facilities with multiple mooring lines, the maximum line tensions for the Hywind mooring system will not increase following a single or double mooring line failure. Failure of one mooring line will rather relax the system and decrease the mooring line forces in the other two lines.
Statistics from the oil and gas industry show that the actual rate of mooring line failure is higher than what is assumed in mooring design standards. Many of the failures are considered to be a result of faults during fabrication, installation or operation, and such failures can be avoided by ensuring proper inspection and maintenance during all phases of project development and operation. Statoil’s internal statistics for mooring line failures their own operated units show a failure rate far below the industry average, and it will be a target for the Project to achieve at least as good a standard for the mooring system on the Hywind Project as for the other units operated by Statoil.
Statoil will develop a robust Emergency Response Plan for the Project, based on experiences from oil and gas installations, other offshore wind projects and the Hywind Demo Project. BP will be invited to participate in a HAZID workshop in connection with this work. In relation to the development of the Emergency Response Plan evaluation of a realistic salvage time, if a drift-off situation occurs, will be carried out.
1 Minutes of meetings and reports will be made available to Marine Scotland if required. 2 DNV_OS-J103 Design of Floating Wind Turbine Structures. 3 DNV GL Assessment of the probability of mooring line failure and the implications for the Forties Pipeline System. Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-9
17.4.3 Assessment criteria The EIA process and methodology are described in detail in Chapter 6. Specific criteria relating to the topic of other sea users have bene developed for ‘sensitivity of receptor’ and ‘magnitude of effect’ as detailed in Table 17-4 and Table 17-5 respectively. The sensitivity of receptor and magnitude of effect are then combined to determine the level of impact and presented alongside a qualitative understanding of likelihood (using the criteria detailed in Chapter 6). The definitions for level of impact and how they relate to significance are presented in Chapter 6, Table 6-1 and Table 6-2.
Table 17-4 Criteria for sensitivity/value of other sea users
Sensitivity/value Definition
Activities of international importance or recovery only possible over long time period e.g. Very high damage to pipeline or subsea cable.
Activities of national importance that may be able to tolerate some disruption, or would be High expected to recover without long term effects.
Activities of regional importance that may be able to tolerate some disruption, or would be Medium expected to recover without long term effects.
Activities of local importance to one or more other marine users, adaptable to and tolerant of Low change, or can recover over a short period of time.
Negligible Activities not likely to be affected by the Project.
Table 17-5 Criteria for magnitude of effect
Magnitude of effect Definition
Severe Permanent or long lasting disruption that threatens the future viability of an approved or licenced activity or service.
Major Temporary disruption that affects an approved or licenced activity or service, but does not threaten future viability.
Moderate Temporary and low level disruption of approved or licenced activity or service.
Minor Little disruption to other sea users.
Negligible No detectable disruption.
17.4.4 Design Envelope This assessment considers the Project parameters which are predicted to result in the greatest environmental impact. This approach ensures that impacts of greater adverse significance would not arise should any other development scenario be taken forward in the final scheme design. With regards to the assessment of impacts on other sea users, the assessment has considered the maximum amount of infrastructure that could be located on the seabed, this comprises:
> WTG Unit anchoring systems which will include anchor chains present on the seabed (150 - 850 m of anchor chain per anchor and a maximum of 15 anchors for the whole Pilot Park);
> Scour protection around the anchors which could be required over an area of up to 15 m beyond the edge of each anchor (base case is no anchor scour protection but some may be required);
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-10
> Inter array cables of which it is assumed there could be up to 5 at 3 km each (i.e. up to 15 km in total) and up to 7.5 km of which could be stabilised with rock;
> An export cable of up to 35 km in length and requiring rock protection along up to 2 km of its length. The rock protection would occupy a 6 m wide corridor;
> Four cable crossings, each requiring 360 m2 of rock protection; and
> Cable landfall installation as a surface laid cable across the foreshore requiring a working corridor of 6 m wide (base case is HDD).
The impacts associated with potential alternative development options are addressed in Section 17.7.
17.5 Impacts during construction and installation
17.5.1 Impacts on cables Installation of the export cable, which will transect existing cables will be undertaken by jet trenchers and mechanical trenchers. Trench width will not exceed 6 m and the installed cable will be buried to a depth of 1.5 m. Installation of the buried cable could potentially result in the damage of existing utilities. Where burial depth cannot be achieved due to the presence of existing cables, the cable will be surface laid and cables crossings bridged as required. Specific details will be contained within crossing agreements that will be in place for each cable crossing.
Assessment of impact significance As cables are nationally important infrastructure, their sensitivity is considered high. The installation of the Project export cable will need to cross a number of cables and there is potential that during this work there could be impacts on the existing cables. However, prior to installation, crossing agreements will be in place which will detail how these crossings will be undertaken, the magnitude of effect is therefore negligible. The overall level of impact is minor and not significant, and unlikely to occur.
Sensitivity / value Magnitude of effect Level of impact High Negligible Minor Impact significance - NOT SIGNIFICANT
MITIGATION
Although no significant impact has been identified, the following mitigation measures will be implemented to ensure this remains the case:
> Crossing agreements will be put in place prior to works to ensure no impact on cables; and
> Where cable owners have not been traced cable crossings will be designed assuming cables are live.
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-11
17.5.2 Inadvertent detonation with consequent damage to equipment or injury to personnel from interaction with UXO The Project commissioned an UXO desktop study and risk assessment including analysis of seabed survey data (Ordtek, 2014). Based on these data there appears to be low probability of any UXO’s in the Project area. However, there will always be a residual risk for accidentally coming into contact with an UXO. The consequence of detonating an UXO would in this case be primarily equipment damage which could result in a schedule impact. Going forward the Project will consider different measures to assure that it has an acceptable approach to UXOs when it comes to installation work and overall Project design. This means that if disturbing seabed away from an existing survey area, the Project will consider performing additional magnetometer survey and possibly also video or ROV inspection to ensure no UXO’s.
Assessment of impact significance The sensitivity of receptor is considered medium and magnitude of effect is considered negligible based on the fact that the above detailed procedures will be followed. The overall level of impact is negligible and not significant, and unlikely to occur.
Sensitivity / value Magnitude of effect Level of impact Medium Negligible Negligible Impact significance - NOT SIGNIFICANT
MITIGATION
> No mitigation measures are proposed as no significant impacts are predicted.
17.6 Impacts during operation and maintenance During operation of the Project, the WTG Units will undergo annual service assumed to take about 70 hours per year per unit with one crew transfer vessel. In addition to regular inspections an average of 10 visits per unit is assumed for unforeseen corrective actions. The substructure, moorings and cables will undergo inspections at an interval of 1-4 years depending on the result of each survey. One survey will require one supply vessel with ROV, each visit is assumed to take approximately 5 days.
Should there be any new users of the sea introduced to the Project area and its immediate vicinity during the operational life of the Project then potential interactions would be assessed as part of the applications being made by the new projects to ensure any impacts are managed and mitigated as required.
17.6.1 Impacts on other cables Maintenance activities during the operational phase of the Project will involve the inspection and servicing of the offshore Project infrastructure and if necessary implementation of corrective action in the event of any unexpected maintenance requirements. Routine maintenance activities will not be of a nature that could have an effect other cables in the area. If there was a requirement to undertake corrective action in the vicinity of existing cables, agreements with cable operators would be made to minimise the risk of any impacts.
Assessment of impact significance As cables are nationally important infrastructure, their sensitivity is considered high. Should there be a requirement for any corrective maintenance, prior to this agreements will be in place which will detail how these works will be undertaken, the magnitude of effect is therefore negligible. The overall level of impact is minor and not significant, and unlikely to occur.
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-12
Sensitivity / value Magnitude of effect Level of impact High Negligible Minor Impact significance - NOT SIGNIFICANT
MITIGATION
Although no significant impact has been identified, the following mitigation measures will be implemented to ensure this remains the case:
> Agreements will be put in place prior to works to ensure no impact on cables.
17.6.2 Impacts from proposed cables Installation of the export cable will cross the proposed NorthConnect interconnector route between Scotland and Norway. Installation of the Hywind export cable is scheduled to take place in 2016 / 2017 prior to the installation and construction phase of NorthConnect which is scheduled for 2017 / 2021 (NorthConnect, 2014). Should the NorthConnect interconnector go ahead then Statoil will enter into a crossing agreement to ensure impacts on both infrastructure are avoided.
Assessment of impact significance Cables are nationally important infrastructure therefore their sensitivity is considered high. The installation of the NorthConnect interconnector will need to cross the Hywind export cable and therefore could result in an impact on the Hywind export cable. Prior to installation, crossing agreements will be in place to detail how crossings will be undertaken, the magnitude of effect is therefore negligible. The overall level of impact is minor and not significant, and unlikely to occur.
Sensitivity / value Magnitude of effect Level of impact
High Negligible Minor Impact significance - NOT SIGNIFICANT
MITIGATION
Although no significant impact has been identified, the following mitigation measures will be implemented to ensure this remains the case:
> A crossing agreement will be put in place with NorthConnect (should this interconnector go ahead) to ensure no impact on the Hywind export cable.
17.6.3 Inadvertent detonation with consequent damage to equipment or injury to personnel from interaction with UXO During the operational phase of the Project no new areas of seabed are expected to be disturbed additional to those disturbed during construction and installation. However, the potential for UXO contamination to be present in the Project area is considered possible as munitions may migrate within the boundary of the site once the Project is operational.
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-13
Assessment of impact significance Depending on the degree of maintenance work and the time lapsed from the original geophysical survey there may be the requirement for additional risk mitigation. However this will need to be evaluated on an activity specific basis. The sensitivity of receptor is considered medium and magnitude of effect is considered negligible. The overall level of impact is negligible and not significant, and unlikely to occur.
Sensitivity /value Magnitude of effect Level of impact Medium Negligible Negligible Impact significance - NOT SIGNIFICANT
MITIGATION
Although no significant impact has been identified, the following mitigation measures will be implemented to ensure this remains the case:
> Should items (or suspect items) of UXO be encountered during any upgrade and/or maintenance work, specific risk management advice will be sought and implemented to address this potential risk. In such circumstances HSL will consult a UXO specialist as appropriate to conduct a risk assessment and explore the options available. There are too many variables involved in such a scenario to make a rigid strategy at this stage.
17.7 Potential variances in environmental impacts (based on Design Envelope) The impact assessment above has assessed the Project options which are predicted to result in the greatest impacts with regards to other sea users. There may be minor variances in impacts depending on the final Project design e.g. turbine micro-siting and cables in the turbine deployment area. These will be defined as part of the detailed design and not significantly alter the impact assessment presented here for other sea users.
17.8 Cumulative and in-combination impacts HSL has in consultation with Marine Scotland and Aberdeenshire Council identified a list of other projects, which together with the Project, may result in potential cumulative or in-combination impacts. The list of projects including details of their status as of June 2014 and a map showing their location is provided in Chapter 6; Table 6-3 and Figure 6-2 respectively.
Cumulative impacts are impacts on other sea users caused by planned and consented offshore wind farms. In- combination impacts are impacts on other sea users as a result of offshore wind farms (and their associated activities) combined with impacts from other marine activities or other users of the sea.
The consideration of which projects could result in potential cumulative or in-combination impacts is based on the results of the project specific impact assessment together with the expert judgement of the specialist consultant. Having considered the information presently available in the public domain, the only project which is considered to have the potential to result in cumulative or in-combination impacts from any other sea users perspective is the NorthConnect interconnector. Discussions between Statoil and NorthConnect have already begun to ensure that if the NorthConnect project goes ahead in the future any impacts on either project will be managed and mitigated against as required to avoid any significant impacts.
17.8.1 Mitigation requirements for potential cumulative and in-combination impacts No mitigation is required over and above the Project specific mitigation. Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-14
17.9 Monitoring Based on the results of the impact assessment no monitoring of impacts on other sea users is proposed.
17.10 References DECC (2014). 27th Licensing Round https://www.gov.uk/oil-and-gas-licensing-rounds#past-licensing-rounds [Accessed 13/02/2014].
MMT (2013). Marine survey report Hywind offshore windfarm. Geophysical survey Peterhead, Scotland July- August 2013. MMT Doc. No: 101462-STO-MMT-SUR-REP-ST13828. Statoil Doc. No: ST13828-Hywind OW.
NorthConnect (2014). NorthConnect Connecting Renewables website http://www.northconnect.no/ [Accessed 25/06/2014].
Ordtek (2014). Unexploded ordnance desk based study with risk assessment. Hywind offshore wind farm. Ordtek project reference: JM5035.
UK Oil and Gas Data (2014). UK Oil and Gas Data website https://www.ukoilandgasdata.com/dp/jsp/PleaseLogin.jsp [Accessed 12/02/2014].
Hywind Scotland Pilot Park Project – Environmental Statement Assignment Number: A100142-S35 Document Number: A-100142-S35-EIAS-001-011 17-15