Alma Field Development Environmental Statement

EnQuest Heather Limited Alma Field Development Environmental Statement

DECC Document Ref: D/4110/2011 Intertek METOC Document Ref: P1459BA_RN2525_Rev0 EnQuest Heather Limited Document Ref: ENQ-KN501-HS-001-ENS-0001

ISSUED: 21 July 2011

WHERE ENGINEERING MEETS THE ENVIRONMENT ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

STANDARD INFORMATION SHEET

Project Name Alma Field Development DECC Reference D/4110/2011 Number Type of Project Small oil field development Undertaker Name EnQuest Heather Limited Undertaker Address 5 Floor Consort House, Stell Road, Aberdeen, AB11 5QF, United Kingdom Licencees / Owners EnQuest Heather Limited (100%) EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea (CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back via new oil production and water injection flowlines to the Uisge Gorm floating production, offloading and storage facility (FPSO). The development will consist of six production wells and two water injection wells (which will be used to drive production due to low reservoir pressures). Wells will be drilled using a combination of water and oil based muds. Cuttings and water based muds will be discharged to sea both at the seabed and from the drilling rig approximately 10m below the sea surface. Oil based mud and cuttings will not be discharged and will be skipped and shipped back to shore for disposal. Due to the relatively short expected field life of the Alma development (ten years), the Uisge Gorm FPSO will be used instead of installing a platform. Produced crude will be collect by shuttle tanker once every Short Description two weeks. The majority of the produced gas will be used for power generation, however there may be a short period early part of field life where excess gas is produced that cannot be burned, this will be flared. All produced water will be re-injected. Production flowlines will be surface laid and protected. The water injection flowline will be trenched and buried, but where trenching is not possible it will be surface laid and protected. Concrete mattresses and rock material will be used for protection. Current estimates are that based on a 10 year field life the base case recovery from the Alma field will be 20.7 million barrels (2.8 million tonnes) and a high recovery case of 32.5 million barrels (4.4 million tonnes). Peak production in the first year will be in the region of 4.5 million barrels (0.61 million tonnes) for the base case and 7.8 million barrels (1.06 million tonnes) for the high recovery case. Construction is scheduled to start in January 2012 with the drilling of the first producer wells. First oil is anticipated in August 2013. Anticipated Start of January 2012 Works Previous / Other Statements Related to N/A this Project EnQuest is aiming to limit environmental effects to low impact through project design, mitigation measures and operational controls. No impacts associated with the development have been categorised as Major or Critical, meaning that the majority of the impacts were assessed as having no or minor residual impact (i.e., impacts can be managed through effective standard operating procedures). A few impacts were assessed as Moderate (i.e., the residual impact has been subject to feasible and cost effective mitigation and no further measures are practicable). Significant During construction and production it is considered that the following activities may have an impact: on Environmental the environment; atmospheric emissions from power generation; anchoring ; discharge of chemicals and Impacts Identified drill cuttings; positioning of structures, rock material and concrete mattressing on the seabed; and the accidental spill of hydrocarbons and/or chemicals. However in all instances the severity of the impact is limited by the nature and composition of the environment and by the fact that these activities are short- term and affect a localised area. With mitigation measures in place, the Alma field development will have a minor impact on the environment. Statement Prepared Intertek METOC and EnQuest Heather Limited By

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NON-TECHNICAL SUMMARY

INTRODUCTION

EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea (CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back via new oil production and water injection flowlines to a floating production, offloading and storage facility (FPSO). Export will be through the use of a shuttle tanker from the FPSO. The proposed Alma development will be located in United Kingdom continental shelf (UKCS) Blocks 30/24 and 30/25, approximately 274km east of the nearest landfall on the Northumberland coastline and approximately 18.5km from the Norway/UK international boundary (median line).

In compliance with regulatory requirements, and to responsibly manage any impacts from the development, EnQuest has carried out an Environmental Impact Assessment (EIA) of the proposed development.

The EIA process establishes the environmental baseline in the area of the proposed development and identifies environmental sensitivities, particularly with relevance to the concerns of stakeholders and regulatory bodies. It also evaluates relevant environmental impacts and their significance, and finally proposes mitigation measures which the operator will implement to minimise these impacts.

This document reports on the EIA process, its findings and conclusions.

GOVERNING LEGISLATION

Offshore oil and gas developments are governed by a collection of international, European Community (EU) and UK laws, policies and guidelines. These dictate the management goals and objectives which an environmental assessment may aim to achieve. The main UK regulations that apply to the project are:

Petroleum Act 1998 – Requires all offshore oil and gas development to apply for consent to undertake the project.

Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) (Amendment) Regulations 2007 – These regulations implement the EC EIA and Public Participation Directive, and require an ES to be submitted for offshore oil and gas projects and public participation in the consent process.

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Offshore Marine Conservation (Natural Habitats, &c.) Regulations 2007 (as amended in 2009 and 2010) – These regulations implement in the UK the EC Habitats Directive (92/43/EC) and the EC Birds Directive (79/409/EC) and aim to protect marine species and wild birds from environmentally damaging activities. It is now an offence under the Regulations to deliberately disturb wild animals of a European Protected Species.

Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 (amended in 2007) – The regulations apply the EC Habitats and EC Birds Directives in relation to oil and gas projects on the UKCS.

PROJECT JUSTIFICATION

Oil is the UK’s second largest source of primary energy, supplying over 30% of the country’s total energy needs (OGUK 2009). In 2008, the UKCS oil production was enough to satisfy 97% of domestic consumption, produced mainly from fields in the Central North Sea (CNS) basin, with some production in the NNS and Southern North Sea (SNS). In 2000, the UK Government identified the need to stimulate oil and gas investment and activity to ensure that indigenous production of oil and gas remained at significant levels into the future. The Promote UK campaign is designed to attract new entrants onto the UKCS, and focused on:

Independent oil companies with the resources to drill wildcat exploration wells and exploit the full value chain from exploration to development; and

Niche ‘developers’, particularly those with the skills to develop previously undeveloped discoveries by using technically innovative and best cost solutions (DECC 2011a).

As a result of these initiatives, EnQuest has been active on the UKCS since 2010. It specialises in predominantly mature areas of the NNS and CNS, aiming to maximise the potential from existing fields and future developments in the UKCS. The longer term strategy is to become a prominent exploration and development operator.

The Alma Field development is part of this strategy and fits many of the UK energy policy objectives:

It would bring on-stream a marginal field that it is now feasible to develop with the prevailing oil price and the small field allowance applicable to this size of field

It is a national resource that will help contribute towards energy security

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Current estimates predict that P501 recovery over field life will be 20.7 million barrels of oil (2.8 million tonnes). P102 recovery is estimated to be 32.5 million barrels (4.4 million tonnes). PROJECT ALTERNATIVES

EnQuest have considered a number of development options for the Alma field. Given the compact nature of the field and relatively short field life, the decommissioning strategy has played an important role in option selection. Options considered included the choice of surface facilities (FPSO, floating production facility (FPF), platform or subsea tie-back), the choice of drilling rig (semi submersible or heavy duty jack-up) and the installation philosophy of the flowlines (trenched and buried or surface laid and protected).

After considerable deliberation, the FPSO, semi submersible and a combination of trenching and surface lay options were selected, based on combination of technical, environmental economic considerations. Table 3-3 details all the pros and cons of each option.

FPSO

A number of FPSOs are available for deployment

Provides an integrated storage and offloading system

Modifications required are more economic that other available options e.g. new platform

FPSOs fit for expected field life

Using an existing FPSO is cheaper than a new build

FPSOs considered have proven track record in the UKCS

Minimal seabed disturbance from installation

Can be easily redeployed at end of field life

Semi Submersible

Less weather dependant during positioning on site

More scope for moving rig but maintaining same anchor pattern – less seabed disturbance. For example, moving to allow subsea infrastructure to be installed, moving rig if subsurface philosophy changes

1 50% confidence level of this volume of oil being produced 2 10% confidence level of this volume of oil being produced

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Ability to drill six wells on same anchor pattern – less seabed disturbance

Easier to run horizontal xmas trees

Better selection options- at least two rigs are known to be available

Current drilling team has extensive knowledge of semi submersible drilling operations

Flowlines Buried

Greater protection for flowlines – no additional protection such as rock would be required except for mattressing and grouting at trench transition areas

Conventional / proven solution

Option to surface protect spans which cannot be buried due to existing subsurface obstructions

Surface Laid

Ease of installation - range of installation vessels available

Benefit as compact field layout with possible drilling rig on site during installation

Lower mobilisation costs for installation

Potential of re-use / decommissioning easier

Conventional / proven solution

Minimal seabed disturbance

Lower risk of subsurface obstructions because no trenching

Additional protection such as rock material will be required for certain spans

Technically preferred option for production flowlines due to temperature issues

PROJECT DESCRIPTION

SCHEDULE

Construction is scheduled to start in January 2012 with the drilling of the first production well. Construction activities will continue through to May 2013 with first oil expected in third quarter 2013. A total of six production wells and two water injector wells will be batch drilled and are

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expected to take approximately three months each to drill and complete. Field life is anticipated to be ten years.

CONSTRUCTION

The development will consist of:

The drilling of six producers and two water injectors

The Uisge Gorm FPSO

Two 10-inch production flowlines, one 10-inch water-injection flowline, two control umbilicals and one power cable

Production wells will target a total of three reservoirs within the Alma Development area: Devonian, Zechstein and Rotliegend. Three production wells will be drilled in five sections using a combination of water based mud (WBM) and oil based mud (OBM), with each section cement cased. The remaining three production wells and the two water injection wells will be drilled in four sections also using a combination of WBM and OBM, with each section cement cased. Cuttings and WBM will either be discharged at the seabed or to sea approximately 10m below sea surface from the drilling rig. All OBM and cuttings will be skipped and shipped to shore for disposal.

The water injection flowline will be trenched and backfilled. In the event of any undulations in the trench (and subsequently the flowline) a contingency will be in place for the provision of approximately 5,000 tonnes of rock for deposition for protection. The rock will be deployed to mitigate any upheaval buckling (less of a problem with flexible flowlines) or pipeline out of straightness events experienced during the trenching and pipe-lay activities. This may be required for pipeline protection, depth of cover anomalies or dropped object protection. The requirement for rock deposition will be identified during post lay survey and if required the rock will be placed accurately utilising a dynamically positioned fall pipe rock installation vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot location. Where trenching is not possible the water injection flowline will be surface laid and protected where required with concrete mattress to eliminate any pipe-spans or seabed obstructions. The production flowlines will be surface laid and protected. They cannot be trenched as the arrival temperature of the production fluids at the FPSO would be too high. After tie-in, the flowlines will be hydrotested and leak tested before being dewatered and then commissioned. Concrete mattresses and rock material will be used for dropped object protection and stability. The water-injection flowlines will terminate directly in the FPSO. The production flowlines will terminate at a bolted straight “T” piece from which flexible risers will

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take produced fluids to the FPSO. All flexible risers will be secured by either vertical piled or gravity base anchors and horizontal clump weight anchors.

The Uisge Gorm FPSO will be held permanently on station without any aid from thrusters or other external sources by nine anchors. Modifications and upgrades will be carried out on the FPSO turret to accommodate the new flowline/umbilical riser systems required to receive and process the Alma hydrocarbons and to export injected water. The upgrades will be finished before the FPSO is mobilised to the field.

Note: Image is for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure

PRODUCTION

Produced crude oil and associated gas will be produced back to the FPSO and oil then offloaded onto shuttle tankers for export.

First oil is currently expected in third quarter 2013. Current estimates are that based on a 10 year field life the base case recovery from the Alma field will be 20.7 million barrels (2.8 million tonnes) of crude oil and a high recovery case of 32.5 million barrels (4.4 million tonnes). Peak production in the first year will be in the region of 4.5 million barrels (0.61

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million tonnes) for the base case and 7.8 million barrels (1.06 million tonnes) for the high recovery case. The reservoir pressure at Alma is such that produced water re-injection is required to ensure that satisfactory quantities of crude oil are produced. Sufficient quantities of gas are expected to be produced with the crude to be used for power generation onboard the FPSO.

Produced water will be passed through a bank of hydrocyclones which will take oil in water (OIW) concentrations from approximately 1000mgl-1 to below 30mgl-1. It will then be routed through a degasser and settling vessel. The produced water then passes through the pumps past an overboard discharge point and into four injection pumps that push the produced water down the water injection flowline to be re-injected. Should any produced water be discharged (due to temporary failure, or routine maintenance of the produced water reinjection system) then OIW concentrations will be below 30mgl-1.

Early in the field life there will be the need to flare gas. This would be due to either insufficient gas production to power the generators on the FPSO or because of an excess of gas produced, over that demanded for fuel.

DECOMMISSIONING

Field life is expected to be ten years. Before the end of field life, arrangements for decommissioning will be developed in accordance with the prevailing UK government and international legislation. The development plan is based on the assumption that similar requirements to current legislation will be applicable. These requirements have been considered in the design of the facilities and during project planning. The impacts of decommissioning activities on the environment have not been assessed under the scope of this document as they will be the subject of a separate EIA.

ENVIRONMENTAL IMPACT AND MITIGATION

Mitigation is an integral part of the Alma development. All of the potential interactions between project activities and environmental receptors are subject to either standard recognised best practice mitigation measures or to impact specific, feasible and cost effective mitigation. In general, the mitigation proposed will be sufficient to reduce the effects of activities to below levels which will cause a significant residual impact. For those where mitigation isn’t enough, the residual impacts are detailed below with a discussion of the mitigation that will help to reduce the impact to the acceptable levels identified.

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The following table summarises the findings of the detailed EIA process undertaken in relation to the Alma development and outlines details of the impacts that were considered to have a residual impact on the environment.

Receptor & Type Baseline & Impact Assessment Significance Mitigation of Impact of Residual Impact Construction Seabed The Alma development area comprises a <1m Minor The footprint of the development will Conditions: thickness of very loose to loose silty shelly sands be minimised. Disaggregation of (with a varying degree of gravel and shells) over surface sediments firm to very stiff sandy gravelly clay. A number of Change in seabed activities have the potential to affect seabed topography conditions e.g., anchoring and the deposition of drill cuttings. When retrieved, the anchors are expected to leave a small area of residual disturbance on the seabed. Seabed currents (0.42ms-1) will ensure that all cuttings piles will disperse quickly, although there is the possibility that they may persist for a number of years Seabed Site surveys of the Alma field indicate that there is Minor Daily recording of chemical use to Conditions: a level of sediment contamination as a result of the allow more refined and efficient use. Sediment historic use of the area for previous oil and gas Where possible chemicals will be contamination developments. It is unlikely that further drilling at recycled, skipped and shipped or re- the site will increase this contamination as injected and not discharged. chemicals discharged at the seabed are typically Selections of chemicals will be made environmentally benign. No OBM will be in accordance with the CEFAS discharged. ranked list, where chemicals ranked Benthic The benthic community is typical of a sandy Minor as lower potential hazards are Communities: biotope with moderate diversity. No rare or preferentially chosen. Potential toxic protected species were identified in the baseline Only chemicals permitted through the effects survey. All seabed chemical discharges will be risk relevant Offshore Chemicals assessed and will be within permitted levels. Regulations chemical permit (i.e. PON15B or PON15C) and that have been subject to a risk assessment will be discharged. Benthic The benthic community is typical of a sandy Minor The development footprint will be Communities: biotope with moderate diversity. No rare or minimised where operationally Physical damage to protected species were identified in the baseline possible. individuals or survey. habitats and A total of 8 anchors will be deployed within a smothering 1,000m (3,281ft) radius of the rig at each drill site. (Anchoring) The total area of seabed impacted by all anchors and chains has been estimated at 4,800m2. Communities are expected to recover within two years following cessation of disturbance. Cuttings discharged at the seabed will have a

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Receptor & Type Baseline & Impact Assessment Significance Mitigation of Impact of Residual Impact Physical damage to direct impact on the benthic community. Cuttings No mitigation envisaged individuals or discharged through the water column could have habitats and an impact on the benthic community as they settle smothering (Drill out on the seabed. Cuttings will be incorporated in cuttings) the sediment through bioturbation and general sediment mobility. Significant erosion of cuttings piles starts when the seabed critical velocity reaches 0.35ms-1 (UKOOA 1999). Seabed currents (0.42ms-1) will ensure that all cuttings piles will disperse quickly, although there is the possibility that they may persist for a number of years. Experience in the CNS region indicates that cuttings piles will persist for 5-10 years. Fish and Mackerel, lemon sole, sprat, haddock and whiting Minor No mitigation envisaged Shellfish: all spawn and/or nurse in the vicinity of the Alma Loss or disturbance development. Spawning occurs mainly between of spawning and April and September, with peaks in May, June and nursery grounds July. Juveniles may be present in the region all effecting stock year round. viability As the majority of the noise generated by offshore oil installations is low frequency (<1kHz), any impact is likely to be minimal. Noise from piling has the potential to have a greater impact; however, the duration of noise generation from piling will be significantly less than that of general construction (including drilling) and the noise generated by vessels present during the construction period. Cuttings discharged through the water column could have an impact on pelagic fish species and could also have an impact on benthic species, spawning grounds and shellfish as they settle out on the seabed. Seabed currents (0.42ms-1) will ensure that all cuttings piles will disperse quickly, although there is the possibility that they may persist for a number of years. Marine Mammals Sightings data suggests that eight species of Minor JNCC guidelines (JNCC 2010) on & Protected cetacean are present within and adjacent to Blocks ‘The protection of marine European Species: 30/24 and 30/25. All cetacean species are Protected Species from Injury and Subsea noise protected under the EC Habitats Directive. Disturbance’ will be followed. In The JNCC risk assessment flowcharts were particular EnQuest are committed to followed to determine whether subsea noise would following the mitigation measures cause deliberate injury or deliberate disturbance. outlined in Appendix B – Statutory The EIA concluded there was a negligible risk of nature conservation agency protocol an offence occurring under the Conservation for minimising the risk of injury to (Natural Habitats &c.) Regulations 1994 (as marine mammals from piling noise amended) (HR) and the Offshore Marine (August 2010). Conservation (Natural Habitats, &c.) Regulations 2007 (as amended in 2009) (OMR). Commercial The project area is not considered to be a Minor A 500m safety exclusion zone will be Fishing: commercially important for fishing. Exclusion from enforced around the drilling rig at Impacts on vessels fishing grounds, the potential impact of anchoring each location. on fish spawning areas and stocks and the A 500m safety corridor will be physical presence of flowlines and concrete established along the route of the mattresses were the only impacts deemed to have

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Receptor & Type Baseline & Impact Assessment Significance Mitigation of Impact of Residual Impact any residual impact after mitigation. production and water injection Shipping and The nearest shipping route is within 2nm of the Minor pipelines between the FPSO and the Navigation: Alma development. Some shipping will be production and water injection drill Impact on vessel displaced from the immediate vicinity of the centres movement development; however there is ample sea room to The drilling rig and construction do so. The 500m safety exclusion zone around the vessels will be appropriately lit and drilling rig is intended to prevent potential collisions sound warnings will be broadcast in with any vessels that may be in the area. This will poor visibility. be enforced by a guard vessel. Users of the sea will be notified of the presence and intended movements of construction vessels via the Kingfisher fortnightly bulletins, Notices to Mariners and VHF radio broadcast. Archaeology: It is unlikely that any remains of archaeological Minor The British Marine Aggregate Physical damage to significance exist within the Alma area. However, Producers Association (BMAPA) undiscovered the proposed mitigation measures would ensure protocol for reporting finds of archaeology damage to the site would be minimised and the archaeological significance will be nature of the discovery properly reported. It is followed therefore likely that any damage would be of minor significance, while the value of the discovery may be of moderate/major (positive) significance. Production Commercial The project area is not considered to be a Minor A 500m safety exclusion zone will be Fishing: commercially important for fishing. The continued enforced around the FPSO. Exclusion from presence of development and the exclusion zones The FPSO will be appropriately lit fishing grounds around the drill centers and the FPSO will typically and sound warnings will be preclude fishing in this area due to the small Potential collision broadcast in poor visibility. development size. risk Users of the sea will be notified of the presence of the FPSO and new safety exclusion zones via the Kingfisher fortnightly bulletins, Notices to Mariners and VHF radio broadcast. All vessels will comply with international navigation regulations and codes. Accidental Events Water Resource: Water quality is likely to deteriorate in the Minor Accidental spills will be kept to a Deterioration in immediate vicinity of the spill (>10 tonnes) as minimum through training, good water quality hydrocarbons are dispersed through the water housekeeping and through column. However, it will be naturally biodegraded storage/handling procedures e.g., by microbes within one to two months (NOAA sumps, drains and bunding should 2006). The concentration and likelihood of natural catch accidental spills. biodegradation will obviously be dependent on the Management controls will be in place scale of the incident. However, generally the to eliminate bunkering spills e.g. only deterioration in water quality will be short –term. bunkering during day light and in Plankton: Marine ecology is typical for the NNS with no rare Minor good weather. Potential toxic or protected benthic species identified in the A location specific OPEP will be in effect baseline survey. Nine cetacean species may place for the drilling rig and an occur in the area, all of which are protected under Addendum to the North Cormorant Benthic the EC Habitats Directive. The region is also Minor Communities: OPEP will be applied for to cover

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Receptor & Type Baseline & Impact Assessment Significance Mitigation of Impact of Residual Impact Potential toxic important for seabirds. production operation. The OPEPs effect Biological receptors are vulnerable to the will detail all emergency procedures accidental release of hydrocarbons and/or that will be in place to minimise any Fish and Minor chemicals. Accidental events are extremely spill. Shellfish: unlikely to occur. A small spill of diesel of crude will EnQuest has access to Tier 1, 2 and Potential toxic rapidly disperse and dilute in the energetic marine 3 oil spill response capabilities effect environment but a large spill as a result of a loss of through Oil Spill Response (OSR). Seabirds: containment on the export tanker and FPSO has Moderate EnQuest is a member of OSPRAG Smothering the potential to have wider reaching impacts. which will provide support in a well Modelling suggest that under typical Marine Mammals Minor blow out event. meteorological conditions, there is the potential for and Protected Control measures will be in place to a oil slick as a result of the loss of the FPSO and Species: ensure rapid response to loss of export tanker inventory to beach along the Smothering flowline containment. These will be coastlines of the majority of countries bordering the outlined in the Alma OPEP. North Sea (total probability of beaching is 1%). Numerous protected areas could potentially be impacted as shown in Figure 8-4. Commercial A major crude oil spill has the potential to cause Minor Fishing: damage to the fishing industry by long-term effects Damage to vessels on fish stocks and damage to market confidence and decrease in and could potentially exclude shipping from a catch number of key shipping lanes. However, the likelihood of such an event occurring is extremely Shipping and rare. Minor Navigation: Impact on vessel movement Other Marine Minor Users: Damage to vessels

CUMULATIVE AND INDIRECT IMPACTS

The main concerns regarding the potential for cumulative and indirect impacts from the proposed development relate to impacts from activities at Alma interacting with:

Other activities within the project

Other oil and gas developments (past and future)

Other marine users, such as windfarms, commercial fishing, marine aggregate extraction areas etc

Climate change

The EIA drew the following conclusions:

The project will not have any significant cumulative or indirect effects with any other oil and gas developments

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The project will not have any significant cumulative or indirect effects with any other seabed users

The project will not exacerbate the changes predicted to occur as a consequence of climate change.

The EIA identified the Alma development will not have any residual impacts on water depth, wind speed or wave conditions. Residual impacts on the environment will be short-term, predominantly affecting marine ecology. As climate change has the potential to affect the biological baseline it is possible that the project can act in combination with climate change to exacerbate this impact. However, the EIA concludes that, following construction, biological communities are anticipated to recover to pre-impact levels/structures or similar within five years (see Section 9.2.4.1). Given the relatively short timescale of the construction impacts, it is considered unlikely that any cumulative impacts from the project and climate change will have significant impacts on marine ecology.

ENVIRONMENTAL MANAGEMENT SYSTEMS

EnQuest’s corporate policies and environmental management system (EMS) provide a fit for purpose framework to implement the mitigation measures proposed in the ES.

The HS&EMS is designed to match the requirements of ISO-14001:2004 and is based on the requirements of the Health and Safety OHSAS 18001 standard. The QMS is certified to BS EN ISO 9001. The purpose of the HS&EMS and QMS is to enhance health, safety, environmental and quality (HSEQ) performance and provide a framework for HSEQ management for all of the activities carried out throughout the company. The management systems are designed to cover HSEQ aspects which EnQuest can control and directly manage and those it does not control or directly manage, but can be expected to influence.

EnQuest requires all contractors, their subcontractors and suppliers to have their own HS&EMS and QMS. Each contractor will be responsible for the HS&E management of their

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scope of work and will operate according to their own HS&E Management System. However, contractors HS&EMS must be compatible with EnQuest’s HS&EMS and they are required to align their HS&E management with EnQuest’s goals and objectives. Their QMS must meet the applicable requirements of the BS EN ISO 9000 series of standards or an agreed equivalent.

A project specific HS&E plan will be developed for the Alma development which will define how EnQuest will manage HS&E risks and activities. The Project HSEQ Engineer is responsible for maintaining and implementing the plan, and for providing HSEQ controls within the project to ensure that the requirements of the EnQuest HSEQ management systems are met.

It is expected that the mitigation measures identified in the EIA process and reported in this ES will be adopted and bridged into EnQuest’s HSEQ Management System through the PLANC register.

CONCLUSIONS

EXISTING ENVIRONMENT

Existing conditions at the Alma development were established through an environmental baseline and habitat assessment survey, which revealed that:

The benthic habitat typically comprised of sparse sandy sediments with low benthic diversity. The majority of benthic taxa were polychaete worms. Stations sampled where historical drilling activity was prevalent were characterised by more disturbance and hydrocarbon contamination tolerant species and lower numbers of sensitive species.

No habitats or species of conservation significance under the UK’s Offshore Marine Conservation (Natural Habitats, &c.) (Amendment) Regulations 2010 were observed during seabed surveys

The environmental baseline is similar to other regions of the CNS where oil and gas activity is prevalent. Meteorological conditions around the project support a dilution and dispersion regime which will rapidly reduce the impact significance of emissions to air, water and seabed (i.e. winds are sufficient to disperse atmospheric emissions, tidal currents refresh the water column within an estimated 1.5 hours, currents are generally sufficient to disperse drill cuttings or sediment piles on the seabed).

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IMPACTS

It should be noted that the majority of activities were assessed as having no or minor residual impact on the receiving environment, with a few identified as having a residual impact of moderate significance. This ES reached the following conclusions with regards to the project’s impacts on the environment:

2 Benthic Environment: The total seabed footprint of the development is 0.04km . Due to fishing activities and previous oil and gas industry activities, the benthos in the project area is typical of a moderately disturbed habitat and consequently species that inhabit the area tend to recover quickly after disturbance. The proposed development is located within an area of previous drilling activity. The development area is sufficiently homogenous that any localised losses are unlikely to affect the integrity of the community as a whole. The placement of protective structures such as concrete mattresses will create new habitat for those species that require hard substrate for anchoring. This could lead to settlement of new species and the potential for a localised change in marine ecology. Current speeds are sufficient to erode cuttings piles and these are unlikely to persist for a long period of time.

Protected Species: No protected species were identified in the marine benthic surveys. Marine mammals are likely to be the only protected species of relevance to the Alma development. Assuming the source to be near the seabed, for a receptor 10m below the surface, the noise would have reduced to approximately 153 dB SEL vertically above the source. This is 7 dB below the lowest of the recognised thresholds for strong avoidance behaviour (160 dB SEL) of marine mammals. In conclusion, and provided mitigation measures are followed, the sound experienced will not exceed the injury thresholds for marine mammals. There is therefore a negligible risk of an offence under the Conservation (Natural Habitats &c) Regulations 1994 (as amended) and the Offshore Marine Conservation (Natural Habitats &c) Regulation 2007 (as amended in 2010).

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Due to the distance of the protected site from the development area, it is unlikely that there will be any impacts during normal activities.

Water/Sediment Quality: During normal activities, the production activities will have a negligible impact on the marine environment.

Commercial Fishing: With consideration of other development activities in the CNS, the project will have a minor contribution to seabed smothering from cuttings piles, infrastructure installation and anchoring. However, this is anticipated to be limited to within the immediate vicinity of the wells. Safety exclusion zones are likely to have a moderate impact on commercial fishing in the area as this will result in vessels being displaced from their fishing grounds. Overall it is concluded cumulative impacts and the in-combination impacts with the fishing industry and other marine users are likely to be of negligible significance.

Oil/Chemical Spill Pollution: In the unlikely event of a major oil spill, a worst case scenario loss of containment of 100,000m3 (87,000 tonnes) of crude oil from the export tanker has been modelled. This indicates that there is a 1% chance of beaching occurring on the majority of coastlines bordering the North Sea. Modelling also indicates that the spill could reach the UK coastline within 8 days and 10 hours and the Danish coastline within 5 days and 12 hours. The spill is likely to have completed dispersed within 417 days. Numerous protected areas along the coastlines of those North Sea countries that could be affected by a spill of this magnitude. EnQuest will have an OPEP in place.

ENVIRONMENTAL MANAGEMENT

The EnQuest corporate policies and environmental management system provide a fit for purpose framework to implement the mitigation measures proposed in this ES. The EMS also provides adequate control and bridging arrangements for EnQuest to ensure that the contractors implement these mitigation measures. During the construction and production operations, a set of permits and consents will be obtained from the regulatory bodies. Permit conditions under these will also be fed into the EMS to ensure compliance. EMS performance will be regularly benchmarked against recommendations from independent verifications, through internal and independent audits and reviews.

With mitigation measures in place, the Alma Field development will have a minor impact on the environment.

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CONTENTS

1 INTRODUCTION ...... 1-1 1.1 THE DEVELOPER ...... 1-1 1.2 PROJECT OVERVIEW ...... 1-1 1.3 FORMAT OF THE ENVIRONMENTAL STATEMENT ...... 1-6 1.4 ES AVAILABILITY ...... 1-7

2 INSTITUTIONAL, POLICY AND REGULATORY FRAMEWORKS ...... 2-1

2.1 RELEVANT POLICY GUIDELINES ...... 2-1 2.2 INTERNATIONAL CONVENTIONS, EC AND UK LAWS AND REGULATIONS ...... 2-1 2.3 SEA AND EIA GUIDELINES ...... 2-5 2.4 UK INSTITUTIONAL FRAMEWORK ...... 2-6 2.5 ENQUEST CORPORATE POLICY ...... 2-6

3 PROJECT JUSTIFICATION AND ALTERNATIVES ...... 3-1

3.1 PROJECT JUSTIFICATION ...... 3-1 3.2 ALTERNATIVES ...... 3-3

4 IMPACT ASSESSMENT METHODOLOGY ...... 4-1

4.1 ENVIRONMENTAL AND HUMAN IMPACT ASSESSMENT PROCESS ...... 4-1 4.2 CUMULATIVE AND INDIRECT IMPACTS ...... 4-12 4.3 EIA STAKEHOLDER CONSULTATION ...... 4-13

5 PROJECT DESCRIPTION ...... 5-1

5.1 SCHEDULE ...... 5-2 5.2 CONSTRUCTION ACTIVITIES ...... 5-2 5.3 PRODUCTION OPERATIONS ...... 5-16 5.4 DECOMMISSIONING ...... 5-19 5.5 PROJECT ACTIVITY SUMMARY ...... 5-20

6 PROJECT FOOTPRINT ...... 6-1

6.1 CONSTRUCTION ...... 6-1 6.2 PRODUCTION ...... 6-11

7 ACCIDENTAL EVENTS ...... 7-1

7.1 TYPES OF ACCIDENTAL EVENT ...... 7-1

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7.2 PROBABILITY OF ACCIDENTAL EVENTS OCCURRING ...... 7-4 7.3 OIL SPILL MODELLING ...... 7-6

8 IMPACTS ON PHYSICAL ENVIRONMENT ...... 8-1

8.1 AIR ...... 8-1 8.2 CLIMATE CHANGE ...... 8-6 8.3 WATER RESOURCES ...... 8-9 8.4 SEABED CONDITIONS ...... 8-16

9 IMPACTS ON BIOLOGICAL ENVIRONMENT ...... 9-1

9.1 PLANKTON ...... 9-1 9.2 BENTHIC COMMUNITIES ...... 9-3 9.3 FISH AND SHELLFISH ...... 9-6 9.4 SEABIRDS ...... 9-11 9.5 MARINE MAMMALS ...... 9-17 9.6 PROTECTED SITES AND SPECIES ...... 9-25

10 IMPACTS ON HUMAN ENVIRONMENT ...... 10-1

10.1 COMMERCIAL FISHERIES ...... 10-1 10.2 SHIPPING AND NAVIGATION ...... 10-7 10.3 OTHER MARINE USERS ...... 10-11 10.4 ARCHAEOLOGY ...... 10-15

11 CUMULATIVE AND INDIRECT IMPACTS ...... 11-1

11.1 OTHER OIL AND GAS DEVELOPMENTS ...... 11-1 11.2 OTHER SEABED USERS ...... 11-5 11.3 CLIMATE CHANGE ...... 11-6

12 ENVIRONMENTAL MANAGEMENT ...... 12-1

12.1 MANAGEMENT SYSTEM ...... 12-1 12.2 PROJECT SPECIFIC ENVIRONMENTAL MANAGEMENT ...... 12-1 12.3 MANAGEMENT OF MITIGATION MEASURES ...... 12-3 12.4 OIL SPILL RESPONSE ...... 12-5

13 CONCLUSIONS ...... 13-1

13.1 THE PROJECT ...... 13-1 13.2 EXISTING ENVIRONMENT ...... 13-1

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13.3 POTENTIAL IMPACTS ...... 13-2 13.4 DECOMMISSIONING ...... 13-3 13.5 ENVIRONMENTAL MANAGEMENT ...... 13-3

14 REFERENCES ...... 14-1

APPENDIX A ENVIRONMENTAL IMPACT ASSESSMENT ...... A-1

A.1 INTERACTION MATRIX...... A-2 A.2 CONSTRUCTION ...... A-3 A.3 PRODUCTION ...... A-20 A.4 ACCIDENTAL EVENTS ...... A-32

APPENDIX B OIL SPILL MODELLING ...... B-1

B.1 INTRODUCTION ...... B-2 B.2 ALMA FIELD DEVELOPMENT ...... B-2 B.3 WORST CASE OIL SPILL MODELLING ...... B-3 B.4 SPILL SCENARIOS AND MODELLING RESULTS ...... B-4 B.5 ENVIRONMENTAL IMPACT ASSESSMENT ...... B-13 B.6 REFERENCES ...... B-14

APPENDIX C SUMMARY OF CHEMICALS ...... C-1

C.1 DRILLING CHEMICALS ...... C-2 C.2 CEMENTING CHEMICALS ...... C-6 C.3 COMPLETION AND OTHER CHEMICALS ...... C-6 C.4 PIPELINE CHEMICALS ...... C-8

APPENDIX D JNCC RISK ASSESSMENT FLOW CHARTS ...... D-1

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TABLES

TABLE 1-1: PROJECT CO-ORDINATES 1-3 TABLE 1-2: STRUCTURE OF THIS ES 1-6 TABLE 3-1: CUMULATIVE (BY YEAR) PRODUCTION PROFILES 3-2 TABLE 3-2: PROS AND CONS OR DIFFERENT DEVELOPMENT SCENARIOS 3-6 TABLE 4-1: PROJECT ACTIVITIES 4-6 TABLE 4-2: EXTRACT FROM THE ALMA ISSUES SCOPING MATRIX 4-7 TABLE 4-3: EXAMPLE DEVELOPMENT ACTIVITY, ASPECT AND IMPACT IDENTIFICATION 4-7 TABLE 4-4: ASSESSMENT PROCESS FOR IDENTIFICATION OF POTENTIAL IMPACTS 4-8 TABLE 4-5: SEVERITY DEFINITIONS 4-9 TABLE 4-6: ENVIRONMENTAL AND HUMAN IMPACT SIGNIFICANCE ASSESSMENT MATRIX 4-10 TABLE 5-1: PROJECT SCHEDULE 5-2 TABLE 5-2: CURRENT UNMODIFIED UISGE GORM VESSEL AND PERFORMANCE DATA 5-3 TABLE 5-3: SACRIFICIAL ANODE COMPOSITION 5-15 TABLE 5-4: SUMMARY OF PROJECT ACTIVITIES AND ASPECTS 5-20 TABLE 6-1: CONSTRUCTION EXHAUST GAS EMISSIONS 6-1 TABLE 6-2: SUMMARY OF CONSTRUCTION NOISE SOURCES AND ACTIVITIES 6-2 TABLE 6-3: SUMMARY OF CHEMICAL DISCHARGES (TONNES) – ONE WELL 6-3 TABLE 6-4: SUMMARY OF CHEMICAL DISCHARGES (TONNES) – EIGHT WELLS 6-3 TABLE 6-5: SUMMARY OF FLOWLINE DISCHARGES 6-4 TABLE 6-6: SUMMARY OF DISCHARGES FROM WELL TIE-IN 6-4 3 TABLE 6-7: TOTAL WASTE WATER DISCHARGE (M ) DURING CONSTRUCTION 6-5 TABLE 6-8: SUMMARY OF UNDERWATER NOISE PRODUCED DURING CONSTRUCTION ACTIVITIES 6-5 TABLE 6-9: WEIGHT AND DISCHARGE FATE OF DRILL CUTTINGS (TONNES) 6-7 TABLE 6-10: SUMMARY OF FLOWLINE INSTALLATION FOOTPRINT ON THE SEABED 6-8 TABLE 6-11: SUMMARY OF SEABED FOOTPRINT - FIELD DEVELOPMENT 6-10 TABLE 6-12: EMISSIONS FROM POWER GENERATION 6-11

TABLE 6-13: CO2 EMISSIONS FOR THE STEAM BOILER FROM POWER GENERATION 6-12 TABLE 6-14: FLARING GAS EMISSIONS DURING PRODUCTION 6-12 TABLE 6-15: PRODUCTION - VESSEL EXHAUST GAS EMISSIONS 6-13 TABLE 6-16: SUMMARY OF PRODUCTION NOISE SOURCES AND ACTIVITIES 6-13 TABLE 6-17: TOTAL WASTE WATER DISCHARGE PER ANNUM FOR FIELD LIFE 6-14 TABLE 6-18: ALMA CHEMICAL INJECTION REQUIREMENTS 6-15

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TABLE 7-1: INDUSTRY RISER AND PIPELINES FAILURE FREQUENCIES 7-6 TABLE 8-1: ANNUAL WIND PERCENTAGE FREQUENCY DISTRIBUTION AT STANDARD HEIGHT (10M) 8-3 TABLE 8-2: AIR QUALITY – POTENTIAL IMPACT IDENTIFICATION 8-5 TABLE 8-3: RECOMMENDED CONTINGENCY ALLOWANCES FOR NET SEA LEVEL RISE 8-7 TABLE 8-4: CLIMATE CHANGE – POTENTIAL IMPACT IDENTIFICATION 8-7

TABLE 8-5: COMPARISON OF UK AND ALMA CO2 EMISSIONS - ANNUAL 8-9 TABLE 8-6: PHYSICAL CHARACTERISTICS OF THE SEA WATER IN THE ALMA FIELD 8-10 TABLE 8-7: SUMMARY OF NORTH SEA SURFACE WATERS CONTAMINANT LEVELS 8-10 TABLE 8-8: SUMMARY OF TIDAL CURRENT SPEEDS AT THE ALMA FIELD 8-11 TABLE 8-9: WAVE CHARACTERISTICS AT ALMA 8-13 TABLE 8-10: MONTHLY WAVE HEIGHT AT ALMA 8-13 TABLE 8-11: WATER RESOURCES – POTENTIAL IMPACT IDENTIFICATION 8-14 TABLE 8-12: WATER DEPTH 8-17 -1 TABLE 8-13: HEAVY METALS IN SEDIMENT (µG.G ) 8-23 TABLE 8-14: SEABED CONDITIONS – POTENTIAL IMPACT IDENTIFICATION 8-25 TABLE 9-1: PLANKTON – POTENTIAL IMPACT IDENTIFICATION 9-2 TABLE 9-2: CONTRIBUTIONS OF THE GROSS TAXONOMIC GROUPS 9-4 TABLE 9-3: SPECIES RANKING 9-4 TABLE 9-4: BENTHIC COMMUNITIES – POTENTIAL IMPACT IDENTIFICATION 9-2 TABLE 9-5: COMMONLY CAUGHT SPECIES 9-7 TABLE 9-6: KEY SENSITIVE PERIODS FOR FISH SPAWNING AND NURSERY 9-7 TABLE 9-7: FISH AND SHELLFISH – POTENTIAL IMPACT IDENTIFICATION 9-8 TABLE 9-8: SEABIRD VULNERABILITY 9-13 TABLE 9-9: SEABIRDS – POTENTIAL IMPACT IDENTIFICATION 9-13 TABLE 9-10: CETACEAN OBSERVATIONS IN THE AREA OF INTEREST 9-18 TABLE 9-11: CETACEAN POPULATION ESTIMATES AND CONSERVATION STATUS 9-19 TABLE 9-12: MARINE MAMMALS – POTENTIAL IMPACT IDENTIFICATION 9-20 TABLE 9-13: SOUND EXPOSURE LEVELS AT DISTANCE 9-23 TABLE 9-14: PROTECTED SITES AND SPECIES – POTENTIAL IMPACT IDENTIFICATION 9-27 TABLE 10-1: VALUE (£) OF LANDING FOR THE ALMA DEVELOPMENT AREA AND SURROUNDING REGION (2004 – 2009) 10-2 TABLE 10-2: COMMERCIAL FISHING – POTENTIAL IMPACT IDENTIFICATION 10-5 TABLE 10-3: SHIP ROUTES 10-8 TABLE 10-4: SHIP/INSTALLATION COLLISION FREQUENCIES ESTIMATED FOR ALMA FPSO 10-9

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TABLE 10-5: SHIPPING AND NAVIGATION – POTENTIAL IMPACT IDENTIFICATION 10-10 TABLE 10-6: WELLS WITHIN 40KM OF THE DEVELOPMENT 10-12 TABLE 10-7: OTHER MARINE USERS’ POTENTIAL IMPACT IDENTIFICATION 10-13 TABLE 10-8: ARCHAEOLOGY POTENTIAL IMPACT IDENTIFICATION 10-17 TABLE 12-1: ENQUEST ENVIRONMENTAL TARGETS 12-2 TABLE 12-2: SUMMARY OF MITIGATION MEASURES 12-4 TABLE B-1: PROJECT CO-ORDINATES B-2 TABLE B-2: SPILL SCENARIOS MODELLED B-5 TABLE B-3: MODELLING RESULTS B-5

FIGURES

FIGURE 1-1: PROJECT LOCATION 1-2 FIGURE 1-2: FPSO RISER HOLD-BACK TETHER EXAMPLE 1-4 FIGURE 2-1: ENQUEST ENVIRONMENTAL POLICY 2-7 FIGURE 3-1: CUMULATIVE (BY YEAR) PRODUCTION PROFILES 3-3 FIGURE 4-1: OVERVIEW OF EIA METHODOLOGY 4-1 FIGURE 4-2: ALMA DEVELOPMENT SURVEY EXTENTS 4-4 FIGURE 5-1: ALMA FIELD DEVELOPMENT 5-1 FIGURE 5-2: UISGE GORM FPSO 5-3 FIGURE 5-3: TURRET MOORING SYSTEM 5-4 FIGURE 5-4: FIELD LAYOUT SHOWING FPSO AND DRILLING RIG ANCHOR PATTERNS 5-5 FIGURE 5-5: TYPICAL SEMI-SUBMERSIBLE DRILLING RIG 5-6 FIGURE 5-6: TYPICAL TOP HAT RISER TETHER UTILISING PILES 5-10 FIGURE 5-7: TYPICAL JET TRENCHING ROV 5-12 FIGURE 5-8: OFFLOADING FROM UISGE GORM FPSO 5-16

FIGURE 5-9: CUMULATIVE TOTAL CO2 (TONNES) FROM UISGE GORM FPSO (JAN-AUG 2008) 5-17 FIGURE 6-1: AREA OF SEABED COVERED BY 1 WELL CUTTINGS PILE 6-8 3 FIGURE 7-1: STOCHASTIC MODEL RUN – 100,000M INSTANTANEOUS SPILL OF 38° API CRUDE OIL (417 DAYS) 7-8 FIGURE 7-2: POSSIBLE BEACHING LOCATIONS 7-8 3 FIGURE 7-3: STOCHASTIC MODEL RUN – 5,830M INSTANTANEOUS SPILL OF DIESEL 7-9 FIGURE 7-4: SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE UK COASTLINE 7-10

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FIGURE 7-5: SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE NEAREST INTERNATIONAL BOUNDARY 7-10 FIGURE 7-6: DIESEL SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE UK COASTLINE 7-11 FIGURE 7-7: DIESEL SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE NEAREST INTERNATIONAL BOUNDARY 7-11 FIGURE 8-1: ANNUAL WIND ROSE FOR THE ALMA AREA 8-4 FIGURE 8-2: GENERAL CURRENT CIRCULATION IN THE NORTH SEA 8-12 FIGURE 8-3: BATHYMETRY AT NORTHERN DRILL CENTRE 8-18 FIGURE 8-4: BATHYMETRY AT SOUTHERN DRILL CENTRE 8-19 FIGURE 8-5: BATHYMETRY AT FPSO LOCATION 8-20 FIGURE 8-6: EXAMPLE OF SEABED SEDIMENTS FROM SURVEY 8-21 FIGURE 8-7: SAMPLING STATIONS LOCATION OVERVIEW 8-24 FIGURE 9-1: SEABED PHOTOGRAPHS OF THE ALMA DEVELOPMENT AREA 9-5 FIGURE 9-2: ENVIRONMENTAL OVERVIEW 9-12 FIGURE 9-3: OIL SPILL BEACHING LOCATIONS IN RELATION TO PROTECTED SITES 9-29 FIGURE 10-1: SEASONAL VARIATION IN FISHING ACTIVITY (2004-2009) 10-3 FIGURE 10-2: AVERAGE ANNUAL CATCH AND VALUE FOR THE ALMA DEVELOPMENT AREA 10-4 FIGURE 10-3: SHIPPING ROUTE POSITIONS WITHIN 10NM OF ALMA LOCATIONS 10-8 FIGURE 10-4: OTHER MARINE USERS 10-14 FIGURE 11-1: GALIA PRODUCTION WELL IN RELATION TO THE WIDER ALMA DEVELOPMENT 11-2 3 FIGURE B-1- SCENARIO 1-WORST CASE CRUDE OIL SPILL OF 100,000M B-7 FIGURE B-2-SCENARIO 2- WORSE CASE CRUDE OIL SPILL TRAJECTORY WITH 30 KNOT WIND TOWARDS THE UK B-8 FIGURE B-3-SCENARIO 3- WORSE CASE CRUDE OIL SPILL TRAJECTORY WITH 30 KNOT WIND TOWARDS THE CLOSEST INTERNATIONAL BOUNDARY (AND DENMARK) B-9 3 FIGURE B-4- SCENARIO 4- INSTANTANEOUS DIESEL SPILL OF 5,830M B-10 FIGURE B-5- SCENARIO 5- WORST CASE DIESEL SPILL TRAJECTORY WITH 30 KNOT WIND TOWARDS THE UK B-11 FIGURE B-6- SCENARIO 6- WORST CASE DIESEL SPILL TRAJECTORY WITH 30 KNOT WIND TOWARDS THE CLOSEST INTERNATIONAL BOUNDARY B-12 FIGURE D-1: RISK ASSESSMENT FLOW CHART FOR DELIBERATE INJURY D-2 FIGURE D-2: RISK ASSESSMENT FLOW CHART FOR NON-TRIVIAL DISTURBANCE D-2 FIGURE D-3: M-WEIGHTING FUNCTIONS FOR LOW-, MID-, AND HIGH-FREQUENCY CETACEANS D-3

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ACRONYMNS AND UNITS

< Less than > More than A ACOPS Advisory Committee on Protection of the Sea ALSF Aggregates Levy Sustainability Fund API American Petroleum Institute B B.P Before Present BAT Best Available Technique bbls Barrels BGS British Geological Society BOP Blow-Out Preventer bopd Barrels of Oil Per Day BS&W Bottom Sediment and Water BSI British Standards Institute bwpd Barrels of Water Per Day C CBD Convention on Biological Diversity CEFAS Centre for Environment, Fisheries and Aquaculture Science

CH4 Methane CMT EnQuest Crisis Management Team CNS Central North Sea CO Carbon Monoxide

CO2 Carbon Dioxide CPR Continuous Plankton Recorder D dB Decibel DECC Department of Energy and Climate Change Defra Department for Environment, Food and Rural Affairs DMRB Design Manual for Roads and Bridges DP Dynamic Positioning DSV Diving Support Vessel DTI Department of Trade and Industry E EC European Commission EEMS Environmental Emissions Monitoring Scheme EIA Environmental Impact Assessment EMS Environmental Management System EPS European Protected Species ERC Emergency Response Centre ES Environmental Statement ESP Electrical Submersible Pump EU ETS European Union Emissions Trading Scheme F FAO Food and Agriculture Organisation FDP Field Development Plan FPSO Floating, Production, Storage and Offloading FRS Fisheries Research Service G GESAMP The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection GGL Gardline Geosurvey Limited GIS Geographical Information Service

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H HQ Hazard Quotient HR Conservation (Natural Habitats &c.) Regulations 1994 (as amended) HSE Health and Safety Executive HSEQ Health, Safety, Environmental and Quality Hz Hertz I IBA Important Bird Areas ICES International Council for the Exploration of the Seas IMT Incident Management Team IPPC Integrated Pollution Prevention and Control Directive ISO International Organization of Standardization J JNCC Joint Nature Conservation Committee K KISCA Kingfisher Cables km Kilometre km2 Kilometres squared kPa Kilo Pascal kw Kilo Watt L LAQM Local Air Quality Management (LAQM) Support. Defra, UK Local Air Quality Management LAT Lowest Astronomical Tide M µgl-1 Microgram per Litre µgm-3 Microgram per Cubic Metre µPa Micro Pascal m Metre m2 Metre Squared m3 Cubic Metre MBES Multi-Beam Echo Sounder MCA Maritime and Coastguard Agency MCAA Marine and Coastal Access Act MCZ Marine Conservation Zone MEG Monoethylene Glycol mgl-1 Milligram per Litre mmbbls Million Barrels MMO Marine Mammal Observer MMO Marine Management Organisation MMscf/d Million Standard Cubic Feet per Day MODU Mobile Offshore Drilling Unit ms-1 Metres per Second MW Mega Watt MW(th) Mega Watt (Thermal) MWh Mega Watt Hour

N N2O Nitrous Oxide nm Nautical Miles NNE North-North East NNS Northern North Sea

NO2 Nitrogen Dioxide NOEC No Observed Effect Concentration

NOx Nitric Oxides O OBM Oil Based Mud

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OCNS Offshore Chemical Notification Scheme OCR Offshore Chemical Regulators OESEA Offshore Energy Strategic Environmental Assessment OGED Oil and Gas Exploration and Development OGUK Oil and Gas UK OIW Oil in Water OMR Offshore Marine Conservation (Natural Habitats &c) Regulations 2007 (as amended in 2010) OPEP Oil Pollution Emergency Plan OPPC Oil Pollution Prevention and Control OSPAR Convention for the Protection of the Marine Environment of the North East Atlantic (Oslo Paris Convention) OSRL Oil Spill Response Limited P PAH Polycyclic Aromatic Hydrocarbons PAIH Potential Annex I Habitat PEXA Practice and Exercise Areas PIG Pipeline Inspection Gauge PLANC Permits Licenses Approvals Notifications and Consents PLONOR Posing Little or No Risk PLV Pipeline Laying Vessels PM 10 Particles Measuring 10µm or less PM 2.5 Particles Measuring 2.5µm or less PON Petroleum Operations Notice ppb Parts per billion ppm Parts per million PSA Particle size analysis psia Pounds per Square Inch Atmospheric PW Produced Water PWA Pipelines Works Authorisation PWRI Produced Water Reinjection Q QMS Quality Management System R REACH Registration, Evaluation, Authorisation and restriction of Chemicals ROV Remotely Operated Vehicle RYA Royal Yachting Association S SAC Special Area of Conservation SCANS Small Cetaceans in the European Atlantic and North Sea scfd-1 Standard Cubic Foot per Day SCI Sites of Community Importance SEA Strategic Environmental Assessment SFF Scottish Fishermen's Federation SMRU Sea Mammal Research Unit SNS Southern North Sea SO2 Sulphur Dioxide SoS Secretary of State

SOx Oxides of Sulphur SPA Special Protection Area SPL Sound Pressure Levels SSE Scottish and Southern Energy SSS Sidescan Sonar

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SSW South-South West SUB Substitution T THC Total Hydrocarbons U UK United Kingdom UK BAP UK Biodiversity Action Plan UKCIP UK Climate Impact Programme UKCP United Kingdom Climate Predictions UKCS United Kingdom Continental Shelf UKMMAS UK Marine Monitoring and Assessment Strategy UKOOA United Kingdom Offshore Operators Association (now Oil and Gas UK) UNFCCC United Nations Framework Convention on Climate Change V VHF Very High Frequency VOC Volatile Organic Compounds W WBM Water Based Mud WLCDF Well Life-Cycle Decision Framework

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GLOSSARY

A Air Gun Source of seismic energy used in acquisition of marine seismic data. This gun releases highly compressed air into water. Analogue Survey e.g., bathymetry, sonar imagery and shallow profiling. Technique of representing a sensor's input as amplitude modulated electrical signal (e.g., analogue profiles are output on sweep recorders as opposed to digital). Anode Positive electrode. Appraisal Well Phase of petroleum operations that immediately follows successful exploratory drilling. Appraisal wells might be drilled to determine the size of the oil or gas field and how to develop it most efficiently. Aspect (environmental) Element of an organisations activities, products or services that can interact with the environment. B Backfill The replacement of excavated sediment into a trench. Bathymetry The measurement of the depth of the ocean floor from the water surface; the oceanic equivalent of topography. Beaufort Force Empirical measure (scale of 0 to 12) for describing wind velocity based mainly on observed sea conditions established by Admiral Francis Beaufort (1774 to 1857). Benthic Pertaining to the environment and conditions of organisms living at the bottom of the sea. Biogenic Chemicals or material produced by living organisms or biological processes. Blow-out Uncontrolled flow of reservoir fluids into the wellbore, and sometimes catastrophically to the surface. A blow-out may consist of salt water, oil, gas or a mixture of these. Blow-out Preventer A large valve at the top of a well that may be closed if the drilling crew loses control of the pressure (BOP) within the well. C Catch Per Unit Effort Measurement of the mass of fish caught for a given amount of energy and resources expended by (CPUE) a fishing fleet. Conductor Casing string that is usually put in to the wellbore at the surface to stop the sides of the well falling in. Cone Penetrometer Method of providing data for use in characterising subsurface marine sediments consisting of a Test (CPT) steel cone that is hydraulically pushed into the ground. Sensors on the tip of the cone collect data to classify sediment type by measuring cone-tip pressure and friction. Cuttings Small pieces of rock that break away due to the action of the bit teeth. Cuttings are screened out of the liquid mud system at the shale shakers and are monitored for composition, size, shape, colour, texture, hydrocarbon content and other properties. D Demersal Organisms dwelling at or near the bottom of the sea. Development The phase of petroleum operations that occurs after exploration has proven successful, and before full-scale production. The newly discovered oil or gas field is assessed during an appraisal phase, a plan to fully and efficiently exploit it is created, and additional wells are usually drilled. Downhole In a well bore. E Echolocation Used by animals to orientate, navigate, and find food it is the detection of the position, distance and size of an object by means of reflected sound. Echosounding The action or process of sounding or ascertaining the depth of water or of an object below a ship by measuring the time taken for a transmitted sound-signal to return as an echo. Effort Measure of input extended by people to catch fish (expressed in days fished). Environmental Impact The critical appraisal of the likely effects of a proposed project, activity, or policy on the Assessment (EIA) environment, both positive and negative.

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Environmental A means of submitting to the regulatory authority, statutory consultees, non-government Statement (ES) organisations and the wider public, the findings of an EIA. Epifauna Organisms living on the seabed surface. Epilithic Organisms growing attached to an inorganic substratum, such as rocks, stones, etc. F Flaring The burning of unwanted gas through a pipe. Flaring is a means of disposal used when there is no way to transport the gas to market and the operator cannot use the gas for another purpose. G Geohazard Any geological or hydrological process that poses a threat to people and/or their property. Geophysical The study of the earth by quantitative physical methods, especially by seismic reflection and refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods. Geotechnical The study of soil and rock below the ground to determine its properties. Grey Water Non-industrial wastewater generated from domestic processes such as washing dishes, laundry and bathing. H Hydrotest The process of pumping water through a pipeline at a higher pressure level than is normally used when transporting petroleum to confirm the continued safe operation of the pipeline, ensuring that it's free of any defects. I ICES rectangles Statistical divisions of the sea. Impact (environmental) Any change to the environment, whether adverse or beneficial, wholly or partially resulting from an organisation's activities, products or services. Infauna Organisms that live within the sediment. K Kingfisher Bulletins Fortnightly bulletin providing free safety information to all sea users. Kilometre Point (KP) A general term for the distance along a route from a fixed reference point. L Lowest Astronomical The lowest level that can be expected to occur under average meteorological conditions and under Tide (LAT) any combination of astronomical conditions. M Macrofauna Benthic animals larger than 1 mm in size and include the large polychaete worms, corals, shellfish, and starfish. Magnetometer An instrument for measuring the strength of a magnetic field. MARPOL Convention International Convention for the Prevention of Pollution from Ships (1973/1978). Median Line Offshore international boundary. Mobile Offshore Drilling A generic term for several classes of self-contained floatable or floating drilling machines such as Unit (MoDU) jack-ups, and semi-submersibles. Multivariate Describes a collection of procedures which involve observation and analysis of two or more statistical variables at a time. N North Atlantic A climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of sea-level Oscillation pressure between the Icelandic Low and the Azores high. Notices to Mariners Information issued from a number of different sources, such as the UK Hydrographic Office, Trinity House or Local Harbour Authorities and may contain a variety of information such as chart updates, changes in buoyage, prior warning of activities such as dredging, exclusion zones, etc. O Oil Producer A well producing oil. OSPAR Instrument guiding international cooperation on the protection of the marine environment of the North-East Atlantic. P Pelagic Relating to or occurring or living in or frequenting the open ocean. Petrogenic A contaminant produced from unburned petroleum products. Phytoplankton Microscopic floating plants that exist within the water column.

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Phytoplankton High concentration of phytoplankton in an area, caused by increased reproduction. Bloom Pinger Seismic source. Platform An offshore structure that is permanently fixed to the seabed used to house workers and machinery needed to drill and then produce oil and natural gas in the ocean. Plugged and To prepare a well to be closed permanently with cement plugs and salvage all recoverable Abandoned equipment, usually after either logs determine there is insufficient hydrocarbon potential to complete the well, or after production operations have drained the reservoir. Potential Annex I Habitat (as defined in Annex I of the EC Habitats Directive) identified in offshore areas to be put Habitat (PAIH) forward to the government for protection as part of the Natura 2000 in UK offshore waters programme. Produced Water (PW) Formation water (naturally occurring layer of water in oil and gas reservoirs) and injected water that is produced along with hydrocarbons. At the surface, the water is separated from the hydrocarbons, treated to remove as much of the hydrocarbons as possible and discharged into the sea or injected back into wells. R Ramsar Site Wetland of international importance designated under the Ramsar Convention (1971). Receptor Element of the environment that an environmental aspect can interact with or impact. (environmental) Re-injection (produced Method of enhanced oil recovery to compensate for the natural decline of an oil field production by water) increasing the pressure in the reservoir. Produced water is injected to maintain reservoir pressure and hydraulically drive oil toward a producing well. Reservoir Subsurface body of rock having sufficient porosity and permeability to store and transmit fluids

Rig A drilling unit that is not permanently fixed to the seabed, e.g., a drillship, a semi-submersible or a jack-up unit. Also means the derrick and its associated machinery. Riser The pipe which connects a rig or platform to a subsea wellhead or subsea pipeline during drilling or production operations to take mud returns to the surface; or the pipe which connects a pipeline to a platform. S Seismic Pertaining to waves of elastic energy, such as that transmitted by P-waves and S-waves, in the frequency range of approximately 1 to 100 Hz, used to interpret the composition, fluid content, extent and geometry of rocks in the subsurface. Semi-Diurnal Occurring once every 12 hours. Semi-Submersible Rig Floating vessel that can be used for drilling supported primarily on large pontoon-like structures submerged below the sea surface usually anchored with six to twelve anchors. Shellfish An aquatic animal, such as a mollusc or crustacean, which has a shell or shell-like exoskeleton. Side-Scan Sonar (SSS) Sonar device used for mapping the seabed. Spawning Reproductive activity of fish; the act of releasing eggs into the water by female fish for fertilisation by male fish. Species A group of related organisms having common characteristics and capable of interbreeding. Stochastic Model A model involving or containing a random variable or variables; involving chance or probability. Subsea Situated or occurring underwater. Subsea Control System Subsea system that provides electro/hydraulic control of subsea and downhole hydraulically operated valves. It also provides a data link to the platform control system conveying subsea/downhole operating parameters and performance. Subsea Control Connects remotely positioned subsea satellite production and/or injection trees to subsea template Umbilical controls or to surface controls on a platform. An umbilical can include up to eighteen separate control hoses within a casing e.g., hydraulic hoses, chemical injection hoses and electrical cables. Suspended (well) A well that has been capped-off temporarily.

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T Taxa Categories in the biological classification system for all living organisms (i.e., kingdom, phylum, class, order, family, genus, species). Thermocline The vertical zone in the water column where temperature changes rapidly with depth. Tie-in An operation in pipeline construction in which two sections of line are connected; a loop tied into the main line. Topside The superstructure of a platform. U Umbilical A conduit through which hydraulic fluids, chemicals, power and data are supplied (see subsea control umbilical). Univariate Describes a collection of procedures which involve observation and analysis of one statistical variable. V Vibrocore Acquisition of seabed sediment cores using a vibrating steel tube which penetrates the seabed to a particular depth. W Water Injector A well in which filtered and treated seawater is injected into a lower water-bearing section of the reservoir, the primary objective typically being to maintain reservoir pressure. Well Head The surface termination of a wellbore that incorporates facilities for installing casing hangers during the well construction phase. The wellhead also incorporates a means of hanging the production tubing and installing the Christmas tree and surface flow-control facilities in preparation for the production phase of the well. Well-Test A test whereby the nature and quantity of the formation fluids in a possible oil- or gas-bearing stratum are determined by allowing them to flow to the surface through the drill string under carefully controlled conditions. X Xmas Tree An array of pipes and valves fitted to a production wellhead to control the flow of oil or gas and prevent a possible blow-out. Z Zooplankton Small aquatic animals that float or weakly swim within the water column. Generally longer than 153 µm, up to about 5,000 µm (5 mm).

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1 INTRODUCTION

EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea (CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back via new oil production and water injection flowlines to a floating production, offloading and storage facility (FPSO). This Environmental Statement (ES) has been prepared on behalf of EnQuest to meet the requirements of United Kingdom (UK) legislation and in support of their field development plan. It covers:

Drilling of six production wells and two water-injection wells

Installation of two 10-inch production flowlines, one 10-inch water- injection flowline, two control umbilicals and one power cable

Installation of the Uisge Gorm Floating, Production, Storage and Offloading (FPSO) facility

Export of crude oil via shuttle tanker

Operation and production of the field for an expected 10 years

1.1 THE DEVELOPER

EnQuest Heather Limited is an independent oil and gas production and development company with a geographic focus on the UK continental shelf (UKCS). The Groups’ asset portfolio comprises primarily producing assets and development opportunities, together with exploration and appraisal opportunities, all of which are located in the UKCS. It has working interests in the Don, Thistle, Deveron, Heather, Ivy and Broom oil fields. EnQuest believes that the UKCS represents a significant hydrocarbon basin in a low-risk region. The UKCS continues to benefit from an extensive installed infrastructure base and skilled labour to develop, operate and manage assets. EnQuest’s management has considerable experience of working in the UKCS region and is familiar with the regulatory authorities and competitive landscape. EnQuest Heather Limited owns a 100% stake of the equity of the Alma Field.

1.2 PROJECT OVERVIEW

As a redevelopment of the Ardmore field, the Alma field will be a small oil development with a field life of ten years. The field is located in UKCS Blocks 30/24 and 30/25, 274km east of the nearest landfall on the Northumberland coastline in the CNS. It is approximately 18.5km from the Norway/UK international boundary (median line). The project location is shown in Figure 1- 1 and the co-ordinates are given in Table 1-1.

REPORT REF: P1459BA_RN2525_REV0 1-1 21/07/2011 2°0'E A 2°40'E 3°20'E A A A A AAA A A A A A A AA A A AAAAAAAAAA A A A A A A )" A A AA Block 30/24 A Northern Drill Centre A A AAA AAA AAA AA A !. A A A A A AA A A A A A A A A A AAAA A A AAAA A AAA A A A A A A A A A A AAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAA A A A )"A Uisge Gorm A A A A A XW A AAA FPSO A A A 56°40'N

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Alma Field Development Environmental Statement Legend Figure 1-1: Project Location Median line

Land Date Wednesday, July 6, 2011 15:10:52 UKCS Block Projection ED 1950 UTM Zone 31N Spheroid International 1924 XW Uisge Gorm FPSO Datum D European 1950 !. Northern Drill Centre Data Source EnQuest, UKDeal, KISCA !. Southern Drill Centre J:\P1459\Mxd\Environmental Statement\.mxd Production Flowline File Reference Figure 1-1 Project Location WI Flowline Produced By Louise Mann Checked XW FPSO Reviewed By Anna Farley )" Platform

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Table 1-1: Project co-ordinates Structure Easting (E) Northing (N) Latitude (N) Longitude (E) Uisge Gorm FPSO 488 250 6 227 000 56° 11' 16.16" 02° 48' 38.45" Northern drill centre (production wells) 485 469 6 228 541 56° 12' 05.72" 02° 45' 56.84" Southern drill centre (water-injection wells) 485 858 6 224 891 56° 10' 07.71" 02° 46' 20.12" Datum: WGS84

1.2.1 Field History

The Argyll field was discovered in 1971 and brought on stream as the UK’s first oilfield by the Hamilton Brothers. The Field was decommissioned in 1992 due to the low oil price prevalent at the time. Between 1975 and 1992 Argyll produced 74.8 mmbbl (million barrels) oil. The final field rate was 5,000 bopd (barrels oil per day) with a 70% water cut. The Argyll Field was renamed Ardmore and redeveloped by Tuscan and Acorn, with second phase first oil in 2003. Between 2003 and 2005 Ardmore produced a further 5.2 mmbbl oil. The field was the decommissioned again in 2008 because of low profitability. EnQuest now plan to rename and redevelop the Ardmore field as Alma as it is now commercially viable to develop from a small marginal field due to the prevailing oil price. As the entire previous field infrastructure was removed during the Ardmore decommissioning, and as Alma is a marginal field and production will likely be short-term, EnQuest are proposing to use an FPSO rather than install a platform. The Field consists of three main productive intervals, namely Zechstein carbonates and evaporates, Rotliegend Aeolian sandstone and Devonian sandstone/siltstone. It is located on a large Palaeozoic, southwest to northeast trending tilted fault block on the south-western flank of the Central Graben. The Field structure measures approximately 2.5km wide and 6km long.

1.2.2 Schedule

1.2.3 Construction

The Alma field development will consist of eight wells; six oil producers and two water-injectors. The water injectors will be drilled from a southern drill centre and the production wells from a northern drill centre. All wells will be tied-back via new flexible flowlines to the Uisge Gorm FPSO. Flowlines will consist of one 10-inch water-injection flowline to the southern drill centre and two 10-inch production flowlines to the northern drill centre. As a general rule the water injection flowline will be trenched and backfilled where possible. In the event of any undulations in the trench (and subsequently the flowline) a contingency will be in place for the provision of approximately 5,000

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tonnes of rock for deposition for protection. The rock will be deployed to mitigate any upheaval buckling (low risk for flexible flowlines) or pipeline out of straightness events experienced during the trenching and pipe-lay activities. This may be required for pipeline protection, depth of cover anomalies or dropped object protection. The requirement for rock deposition will be identified during post lay survey and if required the rock will be placed accurately using a dynamically positioned installation vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot location. Due to the infield debris (both buried and on the seabed), wellheads and the associated infrastructure in place from previous field operations, it is difficult to establish a clear route and therefore it will not always be possible to trench and backfill the flowline. Where it is not possible to trench, the line will be surface-laid and protected by concrete mattresses and grout bags. The use of trenching and backfilling will be optimised and surface laid pipe minimised. The production flowlines cannot be trenched and backfilled as this would result in high arrival temperatures of the production fluids at the FPSO. The flowlines will instead be surface laid and protected by concrete mattresses and rock material where required. Production wells will be fitted with electrical submersible pumps (ESPs) to assist flow rates. The wells will be drilled from a semi-submersible drilling rig. Drilling is expected to commence in January 2012, with the rig remaining on site until April 2013. The production flowlines will terminate in a manifold at the northern drill centre and in a bolted straight “T” piece to the flexible risers beneath the FPSO. This “T” piece will allow for future tie-ins. The risers will then connect to the FPSO in a lazy S configuration. In addition a control umbilical will be surface laid out to each drill centre and a power cable will also be laid out to the production wells. The flowline corridor will be approximately 30m wide to the southern drill centre and 50m wide to the northern drill centre. Each riser will be held in place with a vertical and horizontal hold-back tether. Each hold-back tether will consist of one upper piled or gravity riser base (vertical) and one lower clump weight holdback anchor (horizontal) (Figure 1-2). Figure 1-2: FPSO riser hold-back tether example

Note: Image is for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure.

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It is possible that the flowlines will require dropped object protection around the well head areas. This will take the form of concrete mattresses. It is also likely that the first 50m of the flowlines, control umbilical and power cable will be mattressed. Installation and tie-in of the flowlines is expected to occur between January and April 2013. The Uisge Gorm will be held on station by nine mooring lines, configured in three clusters. The FSPO is secured to the seabed with anchors. The anchors will be within a radius of 1,592m of the FPSO. Mooring installation is expected to commence in September 2012.

1.2.4 Production

First oil from the field is currently expected in third quarter 2013. Production forecasts suggest the field will produce approximately 120,000 barrels of fluids per day (19,080m3). The four production wells are expected to have a high water cut and will be produced with the aid of electric submersible pumps (ESPs). At the start of field life the water / oil ratio will be approximately 70% basic sediment and water (BS&W). As the reservoir declines the water / oil ratio will increase and by the end approximately 90 barrels (14.31m3) of water will be produced for every 10 barrels (1.59m3) of oil. Reservoir pressure will be maintained by produced water reinjection supplemented with treated seawater introduced through the two new water-injection wells. It is expected that a shuttle tanker will visit the FPSO once every two weeks to offload stored crude oil via a loading hose and tanker mooring system. Under normal operations all produced water (PW) will be re-injected with treated seawater into the water-injection wells. There is the possibility that PW may be discharged if one of the water-injection pumps fails. Therefore, a new PW handling process will be installed to ensure oil in water concentrations are below 30mgl-1. The FPSO will be powered by two 14MW steam turbines which can be fuelled by diesel, fuel gas or crude oil. Under normal operations gas produced from the reservoir will be used to power the steam boilers. When gas production proves insufficient to power a boiler it will switch to duel fuel e.g., fuel gas and crude oil. As the boilers will run on gas augmented by crude, no gas will be flared, however there may be a short period during the early part of field life where excess gas is produced that cannot be burned, this will be flared.

1.2.5 Decommissioning

Field life is expected to be ten years and therefore decommissioning and abandonment will occur around 2023. The arrangements for decommissioning the field will be developed in accordance with UK government legislation and international agreements in force at the end of field life. However, the development plan is based on the following assumptions (see Section 5-4):

Plug and abandon all wells

Removal of the conductors to below the mud line

All subsea infrastructure e.g. flowlines, flexible risers, well heads and manifolds will be removed

FPSO will be removed and relocated

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Third party confirmation of seabed clearance These requirements were considered in the design of facilities and during project planning.

1.3 FORMAT OF THE ENVIRONMENTAL STATEMENT

This ES is divided into the principal sections outlined in Table 1-2. Table 1-2: Structure of this ES Section Title Content - Non-Technical Summary The aim of the non-technical summary is to enable communication with those unfamiliar with the environmental impact assessment (EIA) process and terminology by summarising the key findings of the ES document in simple terms. 1 Introduction An introduction describing the developer and summarising the project. 2 Institutional, Policy and A description of the legislative frameworks which govern the project and the EIA. Regulatory Frameworks 3 Project Justification This section justifies why the project is preferable to alternative options elsewhere. 4 EIA Methodology A description of the process followed when conducting the EIA. 5 Project Description A description of the project in terms of the activities that will be undertaken during the construction, operation and decommissioning stages of the project. 6 Project Footprint A quantitative description of the emissions to air, sea and ground from the construction, operation and decommissioning stages of the project. 7 Accidental Events This section describes the types of accidental event that could occur during the construction and production phases of the project and presents a summary of the oil spill modelling undertaken to inform the EIA. 8 Impacts on Physical These sections describe the physical, biological and human baseline environment in the Environment project area and identify those activities of the project that may interact with environmental 9 Impacts on Biological receptors. They evaluate and specify project impacts upon the individual receptors, Environment describing them quantitatively wherever possible (in some cases only a qualitative assessment is possible) and in each case the level of significance has been determined. 10 Impacts on Human Mitigation measures to avoid, reduce or remedy the effects identified in the impact Environment assessment are outlined. 11 Cumulative and In- This section considers cumulative impacts where the project contributes to impacts combination Impacts occurring from other activities or processes. 12 Environmental This section describes the EnQuest corporate and project specific management system Management outlining how EnQuest will manage health, safety and environment activities arising from the project. 13 Conclusions 14 References A Appendix A This section contains the environmental impact assessment tables. B Appendix B This section contains the description of the oil spill modelling carried out for the Alma development and its associated impacts. C Appendix C This section contains a summary of chemicals that could be used for the drilling of the wells. D Appendix D This section contains the JNCC noise assessment flowcharts and graphs used to carry out the noise assessment in Section 8.

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1.4 ES AVAILABILITY

A digital or hard copy of the ES is available on request from:

Burton Millar EnQuest Senior HSE Advisor, Projects Level 5, Consort House Stell Road Aberdeen AB11 5QR

Email: [email protected]

The ES can also be downloaded from the Press Releases area at www.metoc.co.uk.

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2 INSTITUTIONAL, POLICY AND REGULATORY FRAMEWORKS

Offshore oil and gas developments are governed by a collection of international, European Commission (EC) and UK laws, policies and guidelines. These laws, policies and guidelines are implemented through various institutional frameworks. The management goals and objectives that an environmental assessment may aim to achieve are governed by these laws/policies and institutional frameworks. Although not an exhaustive list, the following section outlines the main policies, laws and guidelines relevant to this project and considered in this ES.

2.1 RELEVANT POLICY GUIDELINES

Energy White Paper 2007 and the UK Low Carbon Transition Plan 2009 – Sets out the UK Governments international and domestic energy strategy to respond to the changing circumstances in global energy markets and to address the long term energy challenges the country faces (DTI 2007, HM Government 2009).

Marine Policy Statement – UK Government and devolved administrations have worked together to set out a number of high level marine objectives which articulate the outcomes they are seeking for the UK marine area as a whole. Their vision is to achieve clean, healthy, safe, productive and biologically diverse oceans and seas. The Department for Environment, Food and Rural Affairs (Defra) are responsible for developing this strategy. It sets out the general environmental, social and economic considerations that need to be taken into account in marine planning. Consultation on the Statement and supporting documents has been ongoing since 2008 and the Marine Policy Statement was adopted in March 2011 (Defra 2011).

UK Biodiversity Action Plan (UK BAP) – The UK BAP is the UK Government’s response to the Convention on Biological Diversity (CBD) (1992). It describes the UK’s biological resources and provides detailed plans for the protection of these resources. In 2007 the UK BAP list was reviewed and now includes 1,150 species and 65 habitats. Action plans, which set out priorities, actions, targets and reporting targets, have been created for 382 species and 45 habitats.

2.2 INTERNATIONAL CONVENTIONS, EC AND UK LAWS AND REGULATIONS

2.2.1 International Conventions

Convention for the Protection of the Marine Environment of the North East Atlantic (Oslo Paris Convention (OSPAR) Convention) 1992 – main legislative instrument regulating international cooperation. It concentrates on provisions to protect the marine environment through the use of best available techniques, best environmental practice and where appropriate clean technologies (OGUK 2008). The precautionary principle concept also features prominently. The convention regulates European standards

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on the offshore oil and gas industry, marine biodiversity and baseline monitoring of environmental conditions (OGUK 2008). As a signatory to the Convention, the UK, and therefore the UK oil and gas industry and this project, are governed by the legislative framework the Convention enforces. For example, the OSPAR convention prohibits the discharge of oil based mud (OBM), which determines how drill cuttings are managed during a drilling operation.

Convention on Biological Diversity (CBD) 1992 – this international treaty sets out commitments for maintaining the world's ecological biodiversity as the world develops. The Convention establishes three main goals: the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources. UK Government has reacted to the commitments of the Convention by establishing the UK BAP discussed in Section 2.1.

United Nations Framework Convention on Climate Change (1994) - The Convention sets an overall framework for intergovernmental efforts to tackle the challenge posed by climate change. It recognises that the climate system is a shared resource whose stability can be affected by industrial and other emissions of carbon dioxide and other greenhouse gases. Under the Convention the Government is committed to gather and share information on greenhouse gas emissions and launch national strategies for addressing greenhouse gas emissions (UNFCCC 2008). The convention has also influenced EC and UK legislation, being pivotal in the establishment of the EC Council Directive 2003/87/EC and the UK Greenhouse Gas Emissions Trading Scheme Regulations, discussed in Sections 2.2.2 and 2.2.3.

Convention on Environmental Impact Assessment in a Transboundary Context (Espoo) 1991 – The Espoo Convention sets out the obligations of Parties to assess the environmental impact of certain activities at an early stage of planning. It also lays down a general obligation to States to notify and consult each other on all major projects under consideration that are likely to have a significant adverse environmental impact across boundaries. The Convention was adopted in 1991 and entered into force in 1997. 2.2.2 EC Law

The European Commission issues directives, regulations, decisions, opinions and recommendations (see glossary for definitions) to member states. The above cover all aspects of society from culture, technology and human rights to the environment, wildlife and nature conservation. The development will be subject to a wide range of Directives and Regulations as they are implemented in UK law. A number of the key Directives are listed below:

Council Directive 97/11/EC (EIA Directive) – Amended Directive 85/337/EC on the assessment of the effects of certain public and private projects on the environment. Requires environmental assessments to be carried out for certain types of offshore oil and gas activities.

Council Directive 2003/35/EC (Public Participation Directive) – provides for public participation in respect of the drawing up of certain plans and programmes relating to the environment and amending with regard to public participation and access to justice Council Directive 85/337/EC.

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Council Directive 2001/42/EC (SEA Directive) – The purpose of the Strategic Environmental Assessment (SEA) Directive is to ensure that environmental consequences of certain plans and programmes are identified and assessed during their preparation and before their adoption. This will mean that environmental assessments carried out for individual projects will be able to take advantage of additional data and information on the regional impacts of the oil and gas industry.

Council Directive 92/43/EC (Habitats Directive) – Directive on the conservation of natural habitats and wild fauna and flora. The Directive introduces a range of measures to protect 189 habitats and 788 species listed in the Annexes. Each member state is also required to prepare and propose a national list of sites to be adopted as Special Areas of Conservation (SACs).

Council Directive 79/409/EC (Birds Directive) – The Directive provides a framework for the conservation and management of, and human interactions with, wild birds in Europe. Like the Habitats Directive it introduces a range of measures to maintain the favourable conservation status of all wild bird species across their distributional range and allows for the establishment of Special Protection Areas (SPAs) for rare or vulnerable species.

Council Directive 2008/1/EC (Integrated Pollution Prevention and Control (IPPC) Directive) – replaces Directive 96/61/EC and aims to prevent and control emissions to air, water and soil from industrial installations. The directive aims to increase the use of best available techniques (BATs), to ensure a higher level of environmental protection.

Council Directive 2003/87/EC (EU Emissions Trading Scheme (EU ETS) Directive) – The Directive establishes a scheme for greenhouse gas emissions allowance trading within the European Community. The Directive requires that member states establish national allocation plans for emissions.

Registration, Evaluation, Authorisation and restriction of Chemicals (REACH) - Applies to substances manufactured or imported into the EU in quantities of 1 tonne or more per year. Aims to protect human health and the environment from chemical use.

OSPAR Recommendation 2010/5 on the assessment of environmental impacts on threatened and/or declining species – Requires that Contracting Parties to OSPAR take into consideration the relevant species and habitats on the OSPAR List of threatened and/or declining species and habitats when assessments of environmental impacts of human activities that may affect the marine environment of the OSPAR maritime area are prepared. 2.2.3 UK Law

Although not an exhaustive list, the main UK regulations applying to the project are listed below:

Petroleum Act 1998 – Requires all offshore oil and gas development to apply for consent to undertake the project. Consent is issued by the Secretary of State (SoS) and in addition to giving consent to construct the development authorises the owners to operate the development.

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Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) (Amendment) Regulations 2007 – amend the 1999 regulations of the same name. The regulations implement the EC EIA Directive and Public Participation Directive; requiring an ES to be submitted for offshore oil and gas projects and public participation in the consent process.

Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 (amended in 2007) – The regulations apply the Habitats Directive and Birds Directive in relation to oil and gas projects on the UKCS.

Offshore Marine Conservation (Natural Habitats, &c.) Regulations 2007 (as amended in 2009 and 2010) – These regulations apply in the offshore area of the UK and protect marine species and wild birds through a number of offences that aim to prevent environmentally damaging activities. It is now an offence under the Regulations to deliberately disturb wild animals of a European Protected Species. The regulations also implement in the UK the EC Directives 92/43/EC (Habitats Directive) and 79/409/EC (Birds Directive).

Offshore Petroleum Activities (Oil Pollution Prevention and Control) Regulations 2011 – The regulations are designed to encourage operators to reduce the quantities of hydrocarbons discharged during the course of offshore operations.

Offshore Chemical (Amendment) Regulations 2011 – Requires all offshore operators using and/or discharging chemicals to apply for a chemical permit. With respect to the project this will take the form of Petroleum Operators Notices (PONs) for the drilling (PON15B) and pipeline (PON15C) which will be submitted to the Department of Energy and Climate Change (DECC) in advance of operations.

Merchant Shipping (Oil Pollution Preparedness, Response Co-operation Convention) Regulations 1998 – Under these regulations operators of offshore oil and gas installations and pipelines must have an approved oil pollution emergency plan (OPEP) setting out arrangements for responding to incidents which cause or may cause marine pollution by oil, with a view to preventing such pollution or reducing or minimising its effect.

The Offshore Installations (Emergency Pollution Control) Regulations 2002 – The Regulations give the UK Government powers to intervene in the event of an incident or accident involving an offshore installation where there is, or may be risk of, significant pollution, or where the operator is failing or has failed to implement effective control and preventative operations.

The Greenhouse Gas Emissions Trading Scheme Regulation 2005 – provide a framework for a greenhouse gas emissions trading scheme and implement EC Directive 2003/87/EC. Any installation with combustion plant that on its own or in aggregate with any other combustion plant has a rated thermal input exceeding 20MW(th) is required to be registered under the EU ETS.

The Offshore Combustion Installations (Prevention and Control of Pollution) (Amendment) Regulations 2007 – The regulations implement EC Directive 96/61/EC and apply to combustion installations located on offshore oil and gas platforms where an item of combustion plant on its

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own, or together with any other combustion plant installed on a platform, has a rated thermal input exceeding 50MW(th).

Marine and Coastal Access Act (MCAA) 2009 – The Act seeks to improve management and increase protection of the marine environment. It is a large Act that covers a multitude of provisions. Amongst other things it establishes a new Marine Management Organisation, to produce marine plans, administer marine environmental licensing, enforce environmental protection law and manage marine fisheries, and introduces new mechanisms for the designation of marine conservation zones.

Energy Act 2008 – The provisions of the Coast Protection Act relating to navigation considerations regarding the oil and gas industry were transferred to the Energy Act in April 2011 by the MCAA. The change introduces a formal application process linked the environmental regime for consent to locate fixed infrastructure e.g., pipelines, platforms, wellheads, drilling rigs etc. It will also apply to some vessel activities if the vessel is physically connected to the seabed that could constrain their ability to navigate e.g., drill ships and intervention vessels.

The Merchant Shipping (Prevention of Pollution by Sewage and Garbage from Ships) Regulations 2008 – The regulations implement in the UK the requirements of MARPOL 73/78 Annex IV. It should be noted that MARPOL also defines a ship to include fixed and or floating platforms and these are required where appropriate to comply with the requirements similar to those set out of vessels.

2.3 SEA AND EIA GUIDELINES

The DECC have issued guidance notes regarding the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) (Amendment) Regulations 2007, providing details of the required contents of an ES. This ES takes into account this latest guidance (DECC 2009a). In addition, the DECC has recently released a statement in a letter to industry (23 December 2010) stating that the ES assessment of potential impacts from hydrocarbon releases must be extended to match the scope of the recently amended OPEP guidelines. The EIA process is designed to consider the potential impacts from an individual project, ignoring those from other activities in the area. Although consideration is now being given to cumulative impacts in EIA this is still project specific. As a result of the limitations of the EIA process there is now a push towards using EIA at a more strategic stage of the industry development phase. SEAs consider environmental objectives at policy and planning stages, provide a common basis for EIA preparation and ensures that total activity level in one region does not impose unacceptable regional environmental impacts. In 2001 the EC adopted a Directive on the assessment of the effects of certain plans and programmes on the environment 2001/42/EC (SEA Directive). Although the UK have yet to formally implement this Directive, the DECC has produced a series of SEAs for regions of the UKCS. This project lies within SEA region 2. Once SEAs were completed for all regions of the UKCS an Offshore Energy SEA was undertaken in 2008/2009 to inform further seaward rounds of oil and gas licensing, future licensing for the underground storage of combustible gas in depleted and other offshore oil and/or gas fields and further rounds of offshore wind farm leasing. This OESEA was updated with

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amendments issued in 2011. The technical reports and recommendations made in all of these SEAs were used to inform this EIA.

2.4 UK INSTITUTIONAL FRAMEWORK

Secretary of State (SoS) – The ES review and approval process culminates in an approval from the SoS under the Petroleum Act 1998. The SoS is also the focal point for appeals to decisions. The SoS leads the DECC.

Department for Energy and Climate Change (DECC) – Administers the Petroleum Act 1998 under which project consents are given. They are the principal environmental regulator for the offshore oil and gas industry and are responsible for implementation of the EIA Regulations. They also have representatives at OSPAR as a Regulatory Authority.

Department for Environment Food and Rural Affairs (Defra) – Responsible for implementation of Government programmes for the protection of the environment, food (including fisheries) and rural affairs. At the European and international level Defra represent the UKs interests at OSPAR. The department provides advice to the DECC on a range of subjects including: environmental statements, the interactions between fisheries and offshore operations, offshore construction and drilling activities, marine pollution and chemical use and discharge. In Scotland many of the advisory responsibilities for the offshore oil and gas industry are delegated to Marine Scotland.

Joint Nature Conservation Committee (JNCC) – Responsible for promoting nature conservation at UK and international levels. They are the main government and industry advisor on offshore sensitivities with respect to seabirds and cetaceans. Amongst other roles they advise the DECC on environmental statements and are the body responsible for identification and recommendation on offshore conservation areas under the EC Habitat Directive.

Marine Scotland – Is the directorate of Scottish Government responsible for the integrated management of Scotland’s sea. Amongst other roles they advise the DECC on the Offshore Chemical Regulations and impacts on fish and fisheries.

2.5 ENQUEST CORPORATE POLICY

EnQuest will conduct its operations in a responsible manner that protects the health and safety of people and minimises the impact on the environment. The commitment of EnQuest with respect to environmental issues is laid down in the Environmental policy, presented as Figure 2-1. The Environmental Policy along with the Health & Safety (H&S), Social Responsibility, and Quality Policies are reviewed annually by the H&SEQ management team and communicated to all persons working on behalf of the organisation. EnQuest maintains a comprehensive HSE management system, details of which are provided in Section 11.

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Figure 2-1: EnQuest Environmental Policy

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3 PROJECT JUSTIFICATION AND ALTERNATIVES

3.1 PROJECT JUSTIFICATION

Internationally and nationally, energy demand is growing. Given the current uncertainties in the western economies, the visibility of this demand may not be as good over the next few years as it was at the start of the century. However, irrespective of growth, it is likely that for some time to come the energy demand will be met largely by fossil fuels such as oil, gas and coal (DTI 2007). Currently, oil and gas provide 75% of the UK’s total primary energy demand (OGUK 2010). In 2009, the UKCS oil production was enough to satisfy 94% of domestic consumption, produced mainly from fields in the Central North Sea (CNS) basin, with some production in the NNS and Southern North Sea (SNS). Having access to its own reserves has contributed greatly to the UK’s wealth (OGUK 2010). This security of supply has also enhanced the UK’s self- sufficiency in the international arena, particularly at a time when increased competition for resources and global economic uncertainty is leading to high fluctuations in energy markets and fuel costs. UK oil production peaked in 1999 and is currently declining. Production averaged 0.9 billion barrels of oil equivalent in 2009, a decline of nearly 10% in 2008 production figures (OGUK 2009). In 2020, 70% of the UK’s primary energy will still come from oil and gas, even if the UK’s target to achieve 20% energy from renewable sources3 is achieved. If investment is sustained, the UKCS has the potential to satisfy 50% of the UK oil and gas demand in 2020 (OGUK 2010). However, as consumer demand increases and production continues to decline, at some stage in the future the UK will switch to being a net importer. In 2000, the UK Government identified the need to stimulate oil and gas investment and activity to ensure that indigenous production of oil and gas remained at significant levels into the future. The Promote UK campaign is designed to attract new entrants onto the UKCS, and focused on:

Independent oil companies with the resources to drill wildcat exploration wells and exploit the full value chain from exploration to development; and

Niche ‘developers’, particularly those with the skills to develop previously undeveloped discoveries by using technically innovative and best cost solutions (DECC 2011a). As a result of these initiatives, EnQuest has been active on the UKCS since 2010. It specialises in predominantly mature areas of the NNS and CNS, aiming to maximise the potential from existing fields and future developments in the UKCS. The longer term strategy is to become a prominent exploration and development operator. The development of the Alma Field is part of this strategy and would bring on-stream a marginal field that it is now feasible to develop with the prevailing oil price.

3 The European Council agreed in 2007 to a binding agreement that sets a target for 20% of the EU’s energy to be from renewables by 2020. The UK Energy White Paper commits the UK to see renewables grow as a proportion of the UK electricity supply to 10% by 2010, with an aspirational level of 20% by 2020 (DTI 2007)

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The Alma development fits many of the UK energy policy objectives:

It is an economically viable development that has been designed to maximise reserve recovery within an existing mature province using best cost solutions

It is a national resource that will help to contribute towards energy security As stated above, UK oil production for 2009 was 900 million barrels of oil equivalent (123 million tonnes) (OGUK 2010). Assuming the 10% decline in production noted earlier continues, current annual decline in production will be approximately 90 million barrels (12.3 million tonnes) per year. Current estimates are that, based on an 11 year field life, the base case recovery (P504) from the Alma field will be 19.97 million barrels (2.7 million tonnes) with a high recovery case (P105) of 32.57 million barrels (4.4 million tonnes). The cumulative production profiles for both cases are shown in Tables 3-1 and Figure 3-1: Table 3-1: Cumulative (by year) production profiles Base Case (P50) High Recovery (P10) Year MMbbls Tonnes MMbbls Tonnes 2013 2.16 0.30 2.66 0.36 2014 6.09 0.83 9.32 1.26 2015 8.84 1.21 14.02 1.90 2016 11.02 1.51 17.71 2.40 2017 12.86 1.76 20.75 2.81 2018 14.46 1.98 23.34 3.16 2019 15.91 2.18 25.60 3.46 2020 17.24 2.36 27.62 3.73 2021 18.48 2.53 29.42 3.98 2022 19.62 2.68 31.07 4.20 2023 20.7 2.83 32.57 4.40 Source: EnQuest

The Alma field therefore aligns with UK Energy Policy objectives by providing a cost effective solution for a small scale hydrocarbon resource, in a manner that minimises risk to people and the environment. EnQuest’s participation in North Sea oil and gas exploration and production thus contributes towards achieving the national objectives to prolong indigenous production, and to attract new independent companies into the North Sea.

4 50% confidence level of this volume of oil being produced 5 10% confidence level of this volume of oil being produced

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Figure 3-1: Cumulative (by year) production profiles

3.2 ALTERNATIVES

The consideration of alternatives to a proposed project is a requirement of many EIA processes and a standard requirement of the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) (Amendment) Regulations 2007. A comparison of alternatives helps to determine the best method of achieving the project by indicating the best available technology (BAT) or the best environmental practice (BEP) or at the very least the option which minimises environmental impacts. The type and range of alternatives considered might include:

Supply or activity alternatives e.g., using the location to develop oil reserves or for alternative offshore technologies

Location alternatives, either for the entire project or for individual components e.g., the siting of a platform or the routing of a pipeline

Process or infrastructure alternatives e.g., use of waste-minimising or energy-efficient technology, establishing new infrastructure or using existing facilities

Scheduling alternatives e.g., to avoid sensitive periods of the year for particular environmental receptors The World Bank recommends a tiered approach to the analysis of alternatives. It is designed to bring environmental considerations into all stages of development planning and ideally begins with strategic environmental assessment (SEA) to analyse broad alternatives within a region (Sadler and McCabe 2002). In the UK, a set of SEAs are in place which fulfils this purpose.

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This section discusses:

The alternatives to the proposed project (Section 3.2.1) i.e., why the development of an oil project is considered the best alternative for the area in relation to the UK energy strategy

The alternatives that were considered within the project (Section 3.2.2) e.g., location, process, infrastructure and scheduling alternatives. 3.2.1 Alternatives to the proposed project

In light of declining fossil fuel reserves, part of the UK energy strategy is to encourage the development of alternative energy sources to ensure security of supply (DTI 2007). Offshore technologies being considered include wind farms and wave and tidal devices. Some of the technologies considered are not proven and currently it is only wind farms that are being actively developed on a commercial scale. The UK Government has set a target that 20% of the electricity supply by 2020 will be supplied from renewable energy sources (DTI 2007). The need to reduce carbon emissions whilst ensuring secure energy supplies means that the UK cannot rely on renewable energy alone. The UK will continue to need fossils fuels as part of a diverse energy mix for some time to come (DTI 2007) and as such the development of the Alma reserves is very much in line with the current UK energy policies. The Alma field is a re-development of an existing oil field and is not within a zone designated as a currently feasible site for an alternative offshore technology such as wind. As such, the development of the field is considered to be the best option for providing a new energy source. In terms of alternative oil reserves, EnQuest is always looking for potential new sources of oil, but for commercial reasons they have to target proven reserves first.

3.2.2 Alternatives within the proposed project

EnQuest has investigated a range of development options for the following project elements:

1) Production System 2) Drilling rig 3) Production flowlines These are tabulated below, (Table 3-2) highlighting advantages and disadvantages with respect to technical, economic and environmental considerations. The FPSO was selected as the best production option. For a small development with a relatively short field life such as Alma, the ability to re-use an existing production facility is a key factor - on both economic and environmental grounds. Having selected the FPSO option, the Uisge Gorm was selected as the most suitable for the following reasons:

Alma requires a similar mooring configuration and the vessel has previously worked within 15km from the proposed Alma location

An UKCS North Sea safety case already exists

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Recent North Sea service and maintenance records are up to date for recent production operations

Large range of capacity handling

Can install produced water reinjection (PWRI) with minimal oil in water (OIW) discharge, benefiting environment

Potential for a change from diesel power generation, providing environmental improvement

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Table 3-2: Pros and cons or different development scenarios Option Pro Con Decision 1A: FPSO A limited number of FPSOs are available for deployment Age of available FPSOs / fatigue life Selected Provides an integrated storage and offloading system Substantial modifications required

Modification required are more economic that other available Tanker offloading system potentially higher risk of oil spills than

options e.g. new platform export pipelines

FPSOs fit for expected field life Using an existing FPSO is cheaper than a new build FPSOs considered have proven track record in the UKCS

Minimal seabed disturbance from installation Can be easily redeployed at end of field life 1B; Petrofac Readily available Would require substantial replacement of a number of systems Rejected OE&O FPF-1 Would provide consistent Duty Holder across all EnQuest Assets e.g. process system, accommodation and utilities, riser connection system, helideck, primary and secondary steelwork, Would be suitable for deployment to NNS at end of field life mooring system Established contracting strategy with Petrofac Offshore Fatigue and integrity issues Engineering and Operations (OE&O) No crude storage / offloading capabilities so would require export

routes Limited pipeline export routes 1C: New Systems designed specifically for Field Limited pipeline export routes Rejected platform New facility and equipment designed for field life Utilisation of existing facility and avoidance of new build Latest technology designed into build environmental impacts Definitive build cost Larger seabed footprint than FPSO Lower OPEX costs Jacket structure would require substantial piling operations Substantial costs incurred with build and installation Would require decommissioning at end of field life Higher CAPEX

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Option Pro Con Decision 1D: Subsea No requirement for oil storage Limited opportunities to tie into pipeline export routes. Closest Rejected tie-back No requirement for tanker mooring and offloading facility facility is 19km Lower OPEX costs associated with tanker Would require decommissioning at end of field life Avoidance of potential environmental impacts of crude transfer Potentially larger seabed disturbance with longer export route and tanker fuel oil Additional costs associated with pipeline crossings Avoidance of known seabed hazards from previous operations in Identification of clear pipeline routes difficult due to large amount field of seabed hazards from previous production operations Would incur environmental impacts from pipelay trenching and installation vessel activity. 2A: Semi- Less weather dependant during positioning on site More waiting on weather during operations Selected Submersible More scope for moving rig but maintaining same anchor pattern – Moving to new wellhead location (skidding rig) on same anchor Drilling Rig less seabed disturbance. For example, moving to allow subsea pattern dependent on weather infrastructure to be installed, moving rig if subsurface philosophy More expensive day rates changes, ability to drill six wells on same anchor pattern Potentially larger seabed footprint if consider scour marks from Easier to run horizontal xmas trees anchor catenary as well as anchor mounds Better selection options- at least two rigs are known to be available Current drilling team has extensive knowledge of semi submersible drilling operations 2B: Heavy Lower operation day rates Lower lifting and storage capacity Rejected Duty Jack-up Potentially lower waiting on weather once located on individual Movement between individual wellheads is limited and may Drilling Rig well require full rig move outside of footprint – could lead to greater Potentially smaller seabed footprint (only area of spud cans) seabed disturbance that a semi-submersible Rig availability tighter than for semi-submersibles Spud can disturbance could affect future rig locations Would require additional geotechnical site investigations for spud can placement which could not be covered under Alma surveys in 2010 Riser tensioning capacity is greater in deeper water Jack-up may experience problems with horizontal xmas trees

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Option Pro Con Decision 3B: Buried Greater protection for flowlines – no additional protection such as Larger seabed footprint Selected flowlines rock would be required except for mattressing and grouting at If select low temperature option for flowlines then flowlines could (water trench transition areas not be protected or buried injection) Conventional / proven solution As the flowlines would run quite hot, there would be the Option to surface protect spans which cannot be buried due to requirement for large cooling spools if trenched existing subsurface obstructions Harder to decommission would likely leave in-situ at end of field life Higher mobilisation costs for installation as would need more vessels and equipment Higher risk of subsurface obstructions during trenching which would need to be micro-routed 3A: Surface Ease of installation – range of installation vessels available. Greater risk of damage Selected laid flowlines Benefit as compact field layout with possible drilling rig on site Procurement costs (production) during installation May require dropped object protection e.g. rock material, concrete Lower mobilisation costs for installation mattresses which will increase seabed footprint Potential of re-use / decommissioning easier Less than 1m of silty sand as surface layer. May sink into sand. Conventional / proven solution Risers only solution available with FPSO Minimal seabed disturbance Lower risk of subsurface obstructions because no trenching

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4 IMPACT ASSESSMENT METHODOLOGY

4.1 ENVIRONMENTAL AND HUMAN IMPACT ASSESSMENT PROCESS

The EIA process comprises a number of different phases as follows:

Project definition and understanding how environmental considerations have formed an essential part in the development concept, definition and selection of activities (Sections 3, 5, 6 and 7)

Scoping of potential impacts and information collection on environmental conditions (Sections 4.1.4.1, 8, 9, and 10)

Prediction and assessment of potential impacts (Sections 8, 9 and 10)

Development of management and mitigation measures (Sections 8, 9 and 10)

Residual impact significance assessment (Sections 8, 9 and 10)

Communication and reporting of results These steps are informed by the assessment team, the project engineering and management team and by stakeholder consultation throughout the EIA process as shown in Figure 4-1. Further details of the stakeholder engagement process undertaken for the Alma field and its contribution to the project are provided in Section 4.3. Figure 4-1: Overview of EIA methodology

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4.1.1 Project Definition

The first stage of the EIA process is to establish a detailed understanding and description of the project and its associated emissions, effluents and physical footprint. EnQuest’s project engineers and contractors have defined project activities relating to construction, commissioning, operations and decommissioning of the Alma field, which are presented as the Project Description (Section 5). Working with the project engineers, the assessment team has calculated the footprint of the project on the environment (Section 6), by quantitatively establishing emissions to air, water and the seabed. Where it has not been possible to establish a quantitative footprint, qualitative methods have been used.

4.1.2 Establish Baseline Environment

In order to assess the potential impacts resulting from the project it is necessary to identify the environmental and human conditions that currently exist at the site. The environmental and human attributes which are considered have been divided into the three categories below:

The physical environment: air, climate change, water and seabed conditions (Section 8)

The biological environment: plankton, benthic ecology, fish, shellfish and elasmobranchs, seabirds, marine mammals, protected sites and species (Section 9)

The human environment: archaeology, commercial fishing, shipping and navigation, recreational sea users, other seabed users such as other oil and gas developments, wind farms, marine aggregate extraction and military practice and exercise areas (Section 10) A good understanding of the baseline for these attributes has been achieved through two activities:

Undertaking and review of primary (baseline) field studies

Detailed review of all secondary resources (i.e., existing documentation and literature) The data sources used to describe each environmental or human receptor are listed at the beginning of each baseline sub-category in Sections 7, 8 and 9. A summary of the primary and secondary information sources used for the project are as follows: Primary Data A site survey of the Alma field development was carried out between December 2010 and January 2011 by Gardline Geosurvey (GGL 2011). Geophysical (high resolution seismic, single beam and multi-beam echo sounding, sidescan sonar, magnetometer, chirp and mini airgun), geotechnical (vibrocore and CPT) and environmental (grab sampling and still photography) data were collected over the following areas (Figure 4-2):

8km x 7.1km anchoring conditions survey

3.179km pipeline survey (Northern drill centre to FPSO)

3.329km pipeline survey (Southern drill centre to FPSO)

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1km x 1km well site survey at Northern drill centre

1km x 1km well site survey at Southern drill centre

The aim of the survey campaign was to:

Characterise the seabed and shallow geology in terms of topographical conditions, shallow geological and seabed features, sediment type and sediment particle size distribution

Identify obstructions and debris on the seabed

Characterise the anchoring conditions

To provide a top hole prognosis for the two surveyed proposed well locations

Characterise the benthic community

Determine whether any features of conservation importance are present

All data acquired were of good quality and sufficient resolution to identify physical and biological features of importance, if present. The project area is in a well characterised region of the CNS and available survey data show that the benthic community over the Alma field is typical of the surrounding area.

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Figure 4-2: Alma development survey extents

Source: GGL (2011)

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Secondary data Other data on particular elements of the physical, biological and human environment were obtained from appropriate agencies where required. In addition, existing documentation and literature was used to compile the existing baseline. Specific details for the information resources relating to each aspect assessed are detailed in Sections 8 to 10. Examples of some of the key secondary data sources used are given below.

Strategic environmental assessment (SEA) undertaken by the DECC to inform licensing in the CNS (DTI 2001a)

Offshore Energy SEA – undertaken by the DECC to inform licensing of all energy developments in the UK (DECC 2009b)

Fisheries sensitivity maps for British waters (Coull et al. 1998)

Block specific seabird vulnerability tables for the UK (JNCC 1999)

Cetacean population estimates and distribution obtained from the Sea Mammal Research Unit (SMRU) in the form of the Small Cetaceans in the European Atlantic and North Sea (SCANS-II) final report (SCANS-II 2008) and from the Joint Nature Conservation Committee in the form of the Atlas of cetacean distribution on the north-west European Continental Shelf (Reid et al. 2003)

UK coastal atlas of recreational boating (RYA 2008)

Marine Management Organisation (MMO) commercial fishery catch, landing and effort statistics for the period 2003 to 2009 (MMO 2010)

Information on UK existing oil and gas developments (UK Deal 2010)

License boundary information from the Crown Estate on wind farms and marine aggregate extraction areas (The Crown Estate 2011). The following limitations or assumptions were made when establishing the project environmental baseline:

Third party and publicly available information is correct at the time of publication

Baseline conditions are accurate at the time of physical surveys but due to the dynamic nature of the environment, conditions may change during the construction, operation and decommissioning phases of the development

The development, including surrounding area, will not be subject to unforeseen events of a severe nature 4.1.3 Identification of Project Aspects

Once baseline information had been collated, the assessment of potential changes to the baseline resulting from the Alma development required the identification of project aspects. A project aspect is defined as “an element of an organisations activities, products or services that can interact with the environment” (BSI 2001). To identify the project aspects, proposed activities as described in Section 5, are considered for the construction, operational and decommissioning phases, in terms of their direct or indirect potential to:

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Breach relevant legal standards, corporate environmental policy and management systems

Interact with the existing natural environment including its physical and biological elements

Interact with the existing human environment

Cause significant stakeholder concerns. A summary of the project activity components are listed in Table 4-1. Table 4-1: Project activities Activities Activity Components Construction Presence of vessels (including drilling rig and support vessels) Drilling of wells Installation of FPSO Installation of subsea infrastructure e.g., flowlines, umbilicals, power cables, wellheads, manifolds Production Presence of FPSO Presence and movements of vessels (export tanker and supply vessels) Power generation Start-up gas flaring (if necessary) Discharge of produced water FPSO maintenance Accidental Events Chemical and hydrocarbon release (< 1 tonne) Chemical and hydrocarbon release (< 10 tonnes) Chemical and hydrocarbon release (> 10 tonnes) Overboard loss of equipment or waste

4.1.4 Determination of Potential Impacts

4.1.4.1 Scoping

An Interaction Matrix was developed to illustrate the identified interactions of project aspects and environmental and human resources in a consistent and robust manner. An example of the matrix is included in Table 4-2. Potential impacts were identified through a systematic process whereby each individual project activity was considered with respect to its potential to interact with a physical, biological or human receptor. The project aspects were identified as outlined above and were listed down the vertical column (or ‘y’ axis) of the scoping matrix. The horizontal (or ‘x’) axis was comprised of environmental and human resources and receptors that are susceptible to impacts, grouped into physical, biological and human components. Based on their experience, an understanding of the project description, and the nature and extent of project aspects, the assessment team identified whether a project aspect had the potential to interact (positively or negatively) with the environmental receptors. If it was deemed possible that an interaction may occur this was recorded as a tick () in the matrix cell at the intersection between the aspect and the receptor. The completed Matrix is provided as Appendix A for reference.

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Table 4-2: Extract from the Alma issues scoping matrix

Environmental Receptor Physical Biological Human

Project Aspect Atmosphere Water column Seabed conditions Plankton Benthic communities Fish and shellfish Seabirds Marine mammals Marine protected sites and species Archaeology Commercial fishing Oil and Gas infrastructure Shipping Other marine users* General Construction

Physical presence and movement of drilling rig and support vessels Exhaust gas emissions

4.1.4.2 Prediction and Assessment of Potential Impacts

The prediction of impacts (risk assessment) was undertaken to determine what changes may occur (negative or positive) to the receptor (i.e., environment and human) as a consequence of the project and its associated activities. The diverse range of potential impacts considered in the EIA process resulted in a range of prediction methods being used including quantitative, semi-quantitative and qualitative methods. The impact prediction and assessment process took into account any mitigation or control measures that are part of the project design/project plan. Additional mitigation measures aimed at further reducing identified impacts are then proposed where necessary or as appropriate. Table 4-3 provides an example of an activity associated with the project, its aspects and potential impacts. Table 4-3: Example development activity, aspect and impact identification Project Activity Vessel movements Aspect Exhaust gas emissions Impact Localised deterioration in air quality

Once the impact has been identified, its significance is assessed using the following criteria:

Likelihood – How likely is an impact to occur as a result of an activity (see Section 4.1.4.4 and Table 4-4).

Severity – The severity or consequence of an impact is a function of a range of considerations (see Section 4.1.4.5 and Table 4-5). 4.1.4.3 Nature of Impacts

In considering impacts related to this project, both negative and positive impacts have been identified. Furthermore, direct, secondary, indirect and cumulative impacts are also considered. These are further described below:

Negative Impact - an impact that is considered to represent an adverse change from the baseline condition or introduces a new undesirable factor

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Positive Impact - an impact that is considered to represent an improvement on the baseline condition or introduces a new desirable factor

Direct Impact - impacts that result from a direct interaction between a project activity and the receiving environment (e.g., between occupation of an area of seabed and the habitats which are lost)

Secondary Impact - Impacts that follow on from the primary interactions between the project and its environment as a result of subsequent interactions within the environment (e.g., loss of part of a habitat affects the viability of a species population over a wider area)

Indirect Impact - Impacts that result from other activities that are encouraged to happen as a consequence of the project (e.g., project implementation promotes service industries in the region)

Cumulative Impact - Impacts that act together with other impacts to affect the same environmental resource or receptor 4.1.4.4 Likelihood of Impact Occurrence

The likelihood (probability) of an impact occurring has been defined using the qualitative scale of probability categories in Table 4-5. Likelihood is estimated on the basis of experience and/or evidence that such an outcome has previously occurred. Table 4-4: Assessment process for identification of potential impacts Likelihood Definition Very Unlikely Freak combination of factors required for event to occur.

Unlikely Rare combination of factors required for event to occur.

Possible Could happen with additional factors present.

Likely Not certain. Additional factors may result in event.

Very Likely Almost inevitable an event would result.

4.1.4.5 Impact Severity

In evaluating the severity (positive or negative) of environmental or human impacts, the following factors have been taken into consideration:

Duration of the Impact: how often the impact will occur and for how long will it interact with the receiving environment

Spatial Extent of Impacts: whether the impact effects the local, regional or wider environment

Sensitivity of Receiving Environment: the nature, importance (i.e., whether of local, national, regional or international importance) and the sensitivity or adaptability to change of the receptors or resources that could be affected. This also takes account of any laws, regulations or standards aimed at protecting the receiving environment

Recoverability of Receptor: how long until the receptor will return to pre- impact condition.

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These are further defined in Table 4-5. Table 4-5: Severity definitions Term Value Definition Impact Duration Short 1 • The interpretation of these descriptors varies according to the impact topic. For example, a short term impact to the seabed, such as the Moderate 2 effects of levelling works, may last for a year, whereas a short term Long 3 impact to water quality, such as effects from the discharge of water Permanent 4 based mud, could involve a period of 12 to 24 hours. Spatial Extent • The primary zone of influence of the project. In this instance the local Local 1 region encompasses the area within a radius of 1 km around the project footprint. • Impacts extend beyond project locality to impact on the region. The Widespread 2 region in this instance would encompass the CNS. Extensive 3 • Impacts on a national scale (effects well beyond the CNS). Global 4 • Impacts on a global scale (e.g., global warming). Sensitivity of Receiving Environment • Abundant/ common species/ environment and broadly distributed • Robust in nature and proven to be adaptable to changing Low 1 environments • Valued but not unique • Range/ abundance covers numerous regions • Under pressure but has some ability to adapt to changing Medium 2 environment • Valued locally as an important species or environment • Range/ abundance restricted to a limited number of areas • Under pressure and showing some, but slow, adaptability to High 3 changing environment • Valued regionally as an important species or environment • Rare/ unique species/ environment • Under significant pressure and likely to fail or be irreversibly Very High 4 damaged • Valued globally as an important species or environment Recoverability of Receptors Short 1 • The interpretation of these descriptors varies according to the impact Moderate 2 topic. For example, a long recoverability to plankton species, such as the toxic effects of a chemical discharge may last a few months. Long 3 Whereas a long recoverability to some fish species, such as removal of benthic breeding habitat, could involve a period of 10 to 20 years. Irreversible 4

The outcomes from each of the above factors were then tallied to decide an overall grading value of the severity of a particular impact. Where quantification of potential impacts is possible, the decision has been based on numerical values, representing regulatory limits, project standards or guidelines (e.g., noise and air quality impacts).

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A number of environmental aspects such as ecology, landscape, visual and generally all human impacts require a more qualitative approach for determining severity. Semi-quantitative and/or qualitative methods have therefore been used whereby the criteria have been set according to severity factors as defined in Table 4-6 above. The severity factors have been scored with a numeric value from 1 to 4. The sum of values for each of the factors was used to determine the overall severity as summarised in the scale outlined below:

Negligible (sum of values 4 - 6)

Low (sum of values 7 - 9)

Medium (sum of values 10 – 12)

High (sum of values 13 – 16) 4.1.4.6 Assessing Impact Significance

For the potential impacts associated with the Alma field development, the significance of each impact is determined by assessing the impact severity against the likelihood of the impact occurring as summarised in the impact significance assessment matrix provided in Table 4-6. It is important to emphasise that the resulting significance from these two elements is not the likelihood of the activity occurring, but rather it is the likelihood of that activity causing the impact described. Table 4-6: Environmental and human impact significance assessment matrix Likelihood Severity Very Unlikely Possible Likely Very Likely Unlikely Negligible (4 -6) Insignificant Minor Minor Minor Minor Low (7 - 9) Minor Minor Minor Moderate Moderate Medium (10 – 12) Minor Minor Moderate Moderate Major High (13 – 16) Moderate Moderate Moderate Major Critical

Based on the outcome of the significance assessment the following points need to be considered: Critical Significance

It is not possible to manage or mitigate critical impacts. These require the identification of alternatives (elimination of source of potential impact). Such impacts are intolerable and could potentially result in abandonment of a project. Major Significance

Check that the residual impact has been subject to feasible and cost effective mitigation where possible

Where no further reduction in impact levels can be made, it remains a high-level impact and which may therefore be subject to offsets

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Moderate Significance

Check that the residual impact has been subject to feasible and cost effective mitigation and that no further measures are practicable Minor Significance

Not mitigated further An assessment of the significance of the impacts from the project was undertaken and the results are presented in the technical assessment sections (Section 8 to 10) to follow and Appendix A.

4.1.5 Mitigation of Potential Impacts

Mitigation measures are the actions or systems that are used, or have been proposed, to manage or reduce the potential negative impacts identified. They may also be used to enhance the positive benefits, especially in relation to human issues. Application of mitigation measures to reduce potential negative impacts and enhance the benefits of a proposed activity is achieved by the application of the following mitigation hierarchy:

Avoid at Source/Reduce at Source: Avoiding or reducing at source is essentially designing the project so that a feature causing a potential impact is designed out or altered.

Abate on Site: This involves adding something to the basic design to abate the potential impact – pollution controls fall within this category.

Abate at Receptor: If a potential impact cannot be abated on-site then measures can be implemented off-site.

Repair or Remedy: Some potential impacts involve unavoidable damage to a resource. Repair involves restoration and reinstatement measures.

Compensate/ offset: replace in kind or with a different resource of equal value Mitigation is an integral part of the Alma development. All of the potential impacts identified from this project are subjected to either standard recognised best practice mitigation measures or to impact specific, feasible and cost effective mitigation. The mitigations measures considered pertinent for each environmental and human issue considered are outlined in the individual technical sections to follow, are summarised in Section 12 and detailed in Appendix A.

4.1.6 Residual Impact Assessment

Residual impact is the remaining or mitigated impact level after all avoidance, design and management measures have been taken into account. If the risk assessment determined that after mitigation measures were applied there would be no residual impact no further assessment was undertaken on the impact. If, however, it was concluded that a residual impact may still be expected the impact assessment was re-conducted starting with an assessment of the likelihood and severity, to determine the significance of the residual impact The results of the residual impact assessment are presented in the technical assessment sections (Section 8 to 10) to follow and Appendix A.

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4.2 CUMULATIVE AND INDIRECT IMPACTS

In accordance with the EIA regulations, the EIA has given consideration to cumulative and indirect impacts and interactions. The definitions of these three types of impact overlap, generally without any agreed and accepted definitions. For the purposes of this assessment, the definitions proposed by the European Commission (1999) have been used. The definitions are as follows:

Indirect Impacts – Impacts on the environment, which are not a direct result of the project, often produced away from or as a result of a complex pathway. These are sometimes referred to as secondary impacts. An example of an indirect impact is the impact on commercial fish landings as a consequence of the poor stock recruitment because seabed disturbance has caused the loss of spawning grounds.

Cumulative Impacts – Impacts that result from incremental changes caused by other past, present or reasonably foreseeable actions together with the project. Cumulative impacts can either be the interactions of the same type of activity within:

A single current project e.g., habitat loss caused by pipeline trenching added to the habitat loss cause by the installation of subsea structures leading to an overall larger area of habitat loss than one activity on its own.

Two projects in the same area whether this be historic, future, or a different industry e.g., habitat loss caused by the Alma field development combined with the habitat loss caused by the decommissioning of the previous fields combined with the habitat loss of trawling leading to an overall larger area of habitat loss

Impact Interactions – The reactions between impacts whether between the impacts of just one project or between the impacts of other projects in the area. For example, the discharge of oil in produced water and the discharge of chemicals could individually not have an impact on water quality but combined could mean quality deteriorates past threshold levels. Impacts considered in this ES relate to impacts due to the project and:

Other activities within the project

Other oil and gas projects (past, present and future)

Other seabed users e.g., commercial fishing, wind farms, marine aggregate extraction

Climate change e.g., changes in sea level The assessment of cumulative impacts has been dependant on the public availability of consented developments. It is generally acknowledged that there are difficulties in assessing cumulative impacts via a single-project EIA. One of the objectives of the SEA process was to strategically address cumulative impacts from oil and gas projects on a regional scale. In accordance with the EIA regulations it evaluates "any direct or indirect effects (including secondary, short, medium and long-term, permanent and temporary, positive and negative effects) resulting from the existence of the activity, the use of natural resources and the emission of pollutants, the creation of nuisances and the elimination of waste".

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Section 11 presents, quantitative assessments of the cumulative and indirect impacts and interactions (where possible), qualitative descriptions of impacts including the spatial and temporal scope of the assessments and a discussion of which impacts have not been addressed and why.

4.3 EIA STAKEHOLDER CONSULTATION

Although not a statutory requirement, it is recognised best practice that EIA methodology should also include stakeholder consultation. Early consultation can often be a critical first step to the development of a comprehensive and balanced EIA, especially in areas of heightened sensitivity both environmentally and from a human perspective. Views of the interested parties serve to focus the environmental studies and identify specific issues which require further consideration. Figure 4-1 presents a graphical depiction of the process followed and identifies that stakeholder consultation is a key component to the whole process. Through previous project experience and consultation with the authorities, the key stakeholders identified for the Alma field development are the DECC, the JNCC, Marine Scotland and the Scottish Fishermen’s Federation (SFF). Consultation has been undertaken by EnQuest with the aforementioned stakeholders on the proposed scope of the EIA.

High level discussions have been held with Michael Sutherland at SFF. EnQuest presented overview of development and subsea infrastructure. SFF had no upfront objections.

The HSE and the DECC were consulted on suitability of using the FPSO in terms of environmental performance.

Consultation between the DECC and EnQuest regarding the proposal to lay all flowlines on surface unprotected. Responses and advice from all consultees have been incorporated into project planning.

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5 PROJECT DESCRIPTION

The project description covers activities to be undertaken during construction, commissioning, production and the decommissioning of the development after the end of production life. Also provided in this section is an outline schedule, setting out the likely timetable over which these activities will be performed. The section provides the basis upon which the prediction and evaluation of the environmental and human impacts has been conducted. The key elements of the Alma Field development included in the study are:

Drilling of six production wells and two water injection wells

Installation of two 10-inch production flowlines, one 10-inch water injection flowline, two control umbilicals and one power cable

Installation of the Deepwater Uisge Gorm Floating, Production, Storage and Offloading (FPSO) facility

Export of crude oil via shuttle tanker

Operation and production of the field for an expected 10 years

An overview of the field development is shown in Figure 5-1 below. Figure 5-1: Alma field development

Note: Diagram for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure.

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5.1 SCHEDULE

Construction is scheduled to start in January 2012 with the drilling of the first production well. The FPSO will be installed in January 2013 and flowlines will be installed and commissioned between January and May 2013. First oil is expected in August 2013 (Table 5-1). Table 5-1: Project schedule Activity 2012 2013 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Drilling Flowline installation FPSO installation Field commissioning First oil

5.2 CONSTRUCTION ACTIVITIES

The activities involved during the construction phase include the installation of the FPSO, drilling of wells and installation and commissioning of new flowlines and risers. Information on the activities is generally well defined however, minor changes, if any, will be captured by the PON15 process.

5.2.1 FPSO

EnQuest will use the Uisge Gorm floating production, offloading and storage (FPSO) facility for the field development (Figure 5-2). The vessel entered operation in 1995 at the Flora and Fife field (including Angus and Fergus fields) for Amerada Hess. Current vessel and performance data is provided in Table 5-2. The main functions of the FPSO are:

Control of and receipt of fluids from the subsea wells

Processing of the incoming fluids for separation into stabilised crude, water and gas

Storage of the stabilised crude and offloading into tandem moored shuttle tankers (expected frequency of one tanker per fortnight)

Chemical injection and treatment and re-injection of produced water with an oil content of below 30 mgl-1

Power generation for process, offloading, utilities and ship systems

Utilisation of produced gas for fuel gas

Provide accommodation and helideck for operating and maintenance personnel

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Figure 5-2: Uisge Gorm FPSO

Source: www.bluewater-offshore.com Table 5-2: Current unmodified Uisge Gorm vessel and performance data Vessel data Length 248.3m Breadth 39.9m Depth 20.5m Dead weight tonnage 92,000 Accommodation 65 persons Performance data Storage capacities Exportable crude 94,500 m3 (594,340 bbls) Slop tanks 4,450 m3 (28,000 bbls) Fuel oil 2,400 m3 (15,100 bbls) Processing capacities Fluid capacity 121,000 bpd Crude 57,000 bopd Produced water (max) 100,000 bwpd Oil in water content < 30 ppm Gas (max) 20 MMscfd at 2,500 psia Water injection Capacity (max) 70,000 bwpd Power Main generators 1 x steam turbine, 3 x diesel Capacity 1 x 1,500 kW + 3 x 900 kW Emergency generator 1 x 550 kW diesel

The FPSO is held permanently on station without any aid from thrusters or other external sources. This is achieved by using a passive turret mooring system. Nine mooring lines, configured into three clusters, are used, as illustrated in Figure 5-3. The mooring lines come together at the turntable built into the FPSO. The FPSO is able to rotate around the turret to obtain optimal orientation relative to the prevailing weather conditions. The anchor chains are

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secured to the seabed with anchors. At Alma the anchors will be within a radius of 1,592m of the FPSO (Figure 5-4). A 500m safety exclusion zone will be established around the structure enforced by a standby vessel on a 24 hour basis. Figure 5-3: Turret mooring system

Source: www.vryhof.com Modifications and upgrades will be carried out on the FPSO turret to accommodate the new flowline/umbilical riser systems required to receive and process the Alma hydrocarbons and to pump injection water. The upgrades will be finished before the FPSO is mobilised to the field. The upgrades will include:

New chemical injection skid and produced water re-injection pumps

Turret modifications

Upgrades to control system and new subsea control system equipment installed on the subsea trees and on the Uisge Gorm to facilitate full control of the field.

New first stage separator

New and additional power generation (including steam and inert gas)

Well control hydraulics

Accommodation upgrades, fabric maintenance, structure and hull steelwork remedial works, painting

Hydrocyclones for water clean-up

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Figure 5-4: Field layout showing FPSO and drilling rig anchor patterns

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5.2.2 Wells

EnQuest plans to drill eight wells:

Six production wells (P1 - P6)

Two water injection wells (W1 and W2) The water injection wells will be drilled from the southern drill centre and the production wells from the northern drill centre (See Figure 5-4). Wells will be drilled from a semi-submersible (semi-sub) mobile drilling unit (MoDU) and will be suspended pending tie-in to the flowlines and FPSO. The production wells will target a total of three reservoirs within the Alma Development area: Devonian, Zechstein and Rotliegend. The wells are expected to have a high water cut (initial 70% basic sediments and water) and will be produced with the aid of ESPs. The wells will be approximately 30m apart (in their respective drill centres) and will be batch drilled from the drilling rig. Drilling on the first production well will start in January 2012, with all production wells due to be completed by October 2012. The drilling rig will then move to the southern drill centre to start on the water injection wells. It is expected that all drilling will finish by April 2013.

5.2.2.1 Drilling rig

EnQuest have a number of rig options that they are considering. They currently have the Transocean John Shaw semi-sub MODU on contract and it is possible that this rig could be used at Alma. If it is not available, due to EnQuest’s other drilling commitments, a semi-sub with a similar specification could be used. The John Shaw (Figure 5-5) is approximately 86m x 65m x 35m (topside) with an operating draft of 21m. It is capable of operating in depths up to 549m, drilling to depths of 7620m and has the berth capacity for 99 personnel. A 500m safety exclusion zone will be established around the rig enforced by a guard vessel on a 24 hour basis. Figure 5-5: Typical semi-submersible drilling rig

Source: www.deepwater.com

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To support the drilling operation, the following systems and services are located on the rig:

Bulk storage – is provided for fuel oil, bulk drilling mud and cement, liquid drilling fluids, drill water and potable water

Pipe and materials storage – covered storage is provided for sacked material, drilling equipment, spares etc, and deck storage for drill pipe casing

Helideck and craneage - for loading/off loading personnel, equipment and supplies

Environmental protection – sewage treatment unit and hazardous and non-hazardous drainage systems, which collect rainwater and/or any minor spills to a drains tank prior to discharge to sea, or allow transfer to tote tanks for shipment to shore and disposal by licensed waste disposal contractors The rig is self-propelled but maintains station by using eight anchors. Anchors will be limited to an established anchor pattern within 1,500m radius of each drill centre (Figure 5-4). The rig is expected to use four 15 tonne and four 12 tonne Vryhof Strevpris anchors in a catenary system. In this anchor system, the anchor chains rest on the seabed and can scour when made to move due to weather conditions. When anchors are lifted clear at the end of the operation, the anchors can cause sediment deposition onto the seabed, creating a mound. Anchor mounds are common where seabed sediments or shallow sub-surface sediments are composed of fine sands or clay. It is possible that up to eight anchor mounds will be created at each drill centre.

5.2.2.2 Well design and drilling

The two main types of drilling fluids (muds) typically used in offshore drilling; water based mud (WBM) and low toxicity oil based mud (OBM), will be used during the wells. Drilling muds have five primary purposes:

To remove the cuttings (produced by the drill bit) from the formation and carry them to surface

Lubricate and cool the drill bit during operation.

Maintain hydrostatic pressure so that gas and fluids from the formation do not enter the well bore causing a kick or blow-out.

Build a filter cake on the hole wall to prevent fluid loss to the formation.

Support and prevent caving of the wall of the hole. The drilling rig circulates the mud by pumping it through the drill string to the drill bit. From here it travels back up the annular space between the drill string and the sides of the hole being drilled. The circulating system is essentially a closed system with the mud recycled throughout the drilling of the well. Various products may be added to make up for losses (to formation), to adjust the mud’s properties, or to overcome difficult conditions (e.g., stuck drill pipe or loss of well pressure of fluid). Three of the six producer wells will be drilled in five sections (36", 26", 17½", 12¼" and 8½" sections). The top two sections will be drilled with water based

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mud (WBM), the middle section will either be drilled with WBM or oil based mud (OBM) and the bottom two sections will be drilled with OBM. The 36" section will be drilled as an open hole using WBM with all cuttings being discharged directly to the seabed. A 30" conductor will be run and cemented into place to support the hole walls. The 26" section will then be drilled with WBM with cuttings also being discharged directly to the seabed. Once complete a 20" casing will be cemented in to the hole and a marine riser installed to allow all further cuttings and drilling fluids to be returned to the rig. The 17½" section will either be drilled with WBM or OBM. If WBM is used then cuttings will be discharged to sea from the rig after passing over the shale shakers. Shale shakers are a vibrating sieve that drilling fluid and cuttings pass over. The liquid phase of the mud passes through the screen wire mess whilst the larger solids including the drill cuttings are retained on the screen and eventually fall off the back of the shaker. The fluids are recycled back into the drilling system whilst the retained solids and drill cuttings are discharged from the rig via a cuttings chute that is typically positioned 10m below the water line. Once the 17 ½" hole section is complete the 13 ⅜" casing will be run and cemented into the wellbore. The 12¼" and 8½" sections will both be drilled using OBM with no discharge of cuttings. The 12 ¼" section will be lined by a 9 ⅝" casing and the 8 ½" hole section will be lined with a 7" liner. The other three producer wells and the two water injection wells will be drilled in four sections (36", 26", 12¼" and 8½" sections). The top two sections will be drilled with WBM and the bottom two sections will be drilled with OBM. The 36" and 26” sections will be drilled as before, however no 17½" section will be drilled for these wells. The 12¼" and 8½" sections will both be drilled using OBM with no discharge of cuttings. The 12 ¼" section will be lined by a 9 ⅝" casing and the 8 ½" hole section will be lined with a 7" liner. OSPAR Decision 2000/3 prevents the discharge of OBM to the marine environment. Therefore, all returned OBM fluids and associated drill cuttings will be collected and skipped and shipped for thermal treatment onshore. A preliminary list of chemicals to be used during drilling is supplied for reference in Appendix B. Chemical and drill cuttings discharges are quantified in Section 6.1.2.1 and 6.1.3.3. The exact formulation to be used for each well will be finalised in a PON15B application submitted to the DECC at least 28 days prior to drilling each well.

5.2.2.3 Cementing

Casing is cemented into place in all the sections of the well bore down to the interface with the reservoir. As each diameter section of the well bore, is finished, sections of metal casing, slightly smaller than the well bore diameter are placed in the hole to provide structural integrity. These are cemented in to place by pushing cement in the space (annulus) between the casing and the borehole. The cement fluids are pre-mixed in pits on the drilling rig before being pumped downhole. To minimise the quantities of chemicals pumped down hole, a cement liquid additive system will be used to calculate the volumes of premixed fluid required for the job. It is possible that dead volumes (approximately 10%

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of the total mixed) may remain in the pit after the operation, which will be discharged to sea. A preliminary list of chemicals to be used during cementing is supplied for reference in Appendix B and summarised in Section 6.1.2.1. The exact chemicals to be used for each well will be finalised in a PON15B application submitted to the DECC at least 28 days prior to drilling each well.

5.2.2.4 Completion

The wells will be completed with completion components and tubing which are designed to last the life of the wells within acceptable corrosion limits. The completions will include the necessary hardware for the location, operation and power supply for the downhole electric submersible pumps.

5.2.2.5 Well bore clean-up

There will be no flaring associated with the clean-up of the wells. On completion of the 8½" section, the wellbore will be cleaned-up to remove residual quantities of OBM from the casing before the wellbore is suspended by displacing it to inhibited seawater. The clean-up will involve a 60bbls (9.5m3) spacer / detergent mix being circulated in front of the inhibited seawater. The interface between the spacer/detergent mix and the OBM will be contained and back loaded for thermal processing onshore. It is possible that a large cleanup pill of fluid (CLEANPERF) will be run and if used this would be flowed back to the FPSO on well start-up. During the course of operations, EnQuest will follow a hierarchy of choices when dealing with contaminated fluid in order to minimise the volume discharged to sea, in line with Oil and Gas UK "Good Practice for Clean-Up Operations" document (OGUK 2006). The well bore clean-up pill, plus any interface containing visible OBM generated during the clean-up will be shipped to shore for disposal. However, any wastewater containing no visible OBM generated during clean-up will be discharged into the marine environment. This discharge will be permitted under Condition 5 of the relevant PON15B approval. All discharges will be sampled, analysed and reported at the end of the drilling operation. Any residual oils in discharged water are likely to be rapidly dispersed in the water column and broken down through bio-physical weathering processes. If any sheen is observed on the sea surface during wellbore clean-up, this will be reported using a PON 1.

5.2.3 Flowlines and Subsea Infrastructure

Two 10-inch production flowlines and one 10-inch water injection flowline will be installed in the field. A chemical umbilical will be installed out to both drill centres and an additional power cable will be laid to the production drill centre. The umbilicals to the drill centres and the power cables will be surface laid and due to the suitable nature of the seabed will self bury. At the interface between the production and water injection flowlines and the risers up to the FPSO, the flowlines will be connected to the risers with a bolted straight “T” piece with the “T” piece blanked off for potential future tie-ins. The flexible risers will be stabilised using two holdback tethers connected to either two piles for each riser or a gravity base structure (clump weights).

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The risers and umbilicals will be routed up in to the FPSO turret, though guide “I” tubes, to the riser deck where they are hung-off and connected to the turntable system. The riser deck is located above the water level to ease hook- up, inspection and maintenance. All risers are continuous, non-bonded flexible risers running from the riser base structure to the turret in a lazy-S configuration. The water injection flowline will go straight from the riser base structure to the water injection wellheads whilst the production flowlines, umbilical and power cable will terminate at a simple manifold at the northern drill centre. Engineering is currently being carried out to establish the requirement for piles. The preference environmentally is to retain the risers with gravity base structures or clump weights. Should it be established that piles are necessary, then six piles will be required for the holdback tethers on the risers (similar to the one shown in Figure 5-6), two for each riser and will be approximately 24 inches in diameter. It is anticipated each pile will take 2 hours to install. Figure 5-6: Typical top hat riser tether utilising piles

Source: EnQuest

The flowlines are flexible and the base case is for the water injection flowline to be trenched and backfilled and the production flowlines to be surface laid and protected. A large number of seabed obstructions and hazards were identified during the site survey from previous oil exploration and production activities. These included abandoned wellheads, lengths of pipe, wire and a number of spud-can depressions. Due to this and the physical dimensions of the development area it is proving difficult to identify a corridor for the water injection flowline where trenching of the whole route would be possible. Where trenching is not possible the flowline will be surface laid and protected with concrete mattress to eliminate any spans or seabed obstructions. A standby vessel will be on-site during the installation of the flowlines and during production acting as guard vessel, so additional protection has not been

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considered necessary. Dropped object protection (concrete mattresses) will be placed around the wellhead areas.

5.2.3.1 Installation and commissioning of flowlines

Installation of flowlines typically follows the below process:

Trenched and backfilled

Flooded with chemically inhibited seawater

Tied-in at both ends

Hydrotested

Leak-tested

Dewatered and commissioned Prior to the flowlines being laid, an intrusive flowline route obstruction survey will be conducted. The survey vessel will remain on-site for the duration of the installation to provide support to the other construction vessels. It is expected that the flowlines will be laid using a dynamically positioned (DP) pipelay vessel, followed by a vessel with a trenching spread that will jet cut the trenches. The flowline will then be guided into the trench and the dispersed spoil will cover the flowline afterwards. DP vessel A DP vessel will use thrusters to position itself over the pipeline route. A typical vessel used for this type of operation has a draft of 6.5m. The housing for the thruster propellers may extend to a maximum of 2m below this depth. The propellers create disturbance in the water column typically to 5m, below which the effects are not discernible from natural currents and wave orbital movements. Therefore, the deepest effects from a DP vessel are anticipated to reach down to approximately 14m from the sea surface. At the start of the installation process an initiation anchor (typically a conventional 13½ tonne anchor or similar) will be used to help position the vessel and flowline in the target box. However, during the installation process the vessel will not use anchors for positioning. Installation Touch-down of the flowlines will be monitored by a ROV. Installation is expected to take place between January and August 2013. The production flowlines will be laid on the seabed and then protected with concrete mattresses as required. Trenching The water injection flowline will be trenched by a vessel equipped with a jet trenching ROV, similar to the one pictured in Figure 5-7. Jet trenching machines use high pressure water jets to fluidise the seabed beneath the pipeline. The water jets are mounted on swords which are lowered up to 2m in to the seabed on either side of the pipeline. The high pressured water disrupts the sediments, forming a trench full of fluidised material, into which the pipeline sinks under its

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own weight. Any trench created backfills naturally. A trench will be cut for the water injection flowline and is likely to be 2m wide depending on the ROV used and the configuration of the jets. Installation proceeds, on average, at a rate of 1.6km/day (Cranswick 2001). Figure 5-7: Typical jet trenching ROV

Source: www.ctcmarine.com

Trenching is expected to take up to 2 days to complete, allowing for any delays. The trench will be initiated and terminated 50m from the FPSO and drill centres. The target depth for the trench will be 1m allowing for 0.6m cover from top of flowline to mean seabed level. The trench depth has been selected based on a consideration of the geotechnical characteristics of the area, the geotechnical site survey (GGL 2011) and from estimated upheaval buckling criteria. The trench depth selected has been designed to eliminate the need for rock dumping. After trenching and backfill the final seabed profile will be a shallow depression over the flowlines due to the loss of finer sediments from displaced material through winnowing. In the event of any undulations in the trench (and subsequently the flowline) a contingency will be in place for the provision of approximately 5,000 tonnes of rock for deposition for protection. The rock will be deployed to mitigate any upheaval buckling or pipeline out of straightness events experienced during the trenching and pipe-lay activities. This may be required for pipeline protection, depth of cover anomalies or dropped object protection. The requirement for rock deposition will be identified during post lay survey and if required the rock will be placed accurately utilising a dynamically positioned fall pipe rock installation vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot location. Commissioning Once installed, the flowlines will be leak tested using inhibited seawater. A dive support vessel (DSV) will be used to pump inhibited seawater into the flowlines. Typically 20% line volume is used to build up the pressure in the line until test pressure has been established and stabilised. Test pressure will be held for 24 hours before the flowlines are depressurised. The inhibited seawater is typically discharged from the DSV at the sea surface. After leak testing, the flowlines will be tied-in at both ends and leak-tested. Leak testing follows a similar procedure to hydrotesting, using inhibited

REPORT REF: P1459BA_RN2525_REV0 5-12 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

seawater. Additional quantities of inhibited seawater pumped into the flowlines to establish leak test pressures will be discharged as above. Once fully installed and tested, the volumes of inhibited seawater remaining in the production flowlines will be flowed ahead of produced fluids to the FPSO where they will pass through the process system. Volumes in the water injection flowline will be pushed into the water injection wells. Exact details of the chemicals to be used during flooding, hydrotesting and leak-test were not available at the time of the ES submission, but will be provided in the PON15C for each flowline as required under the Offshore Chemical (Amendment) Regulations 2011. In total, four vessels will be used for flowline installation and commissioning:

Survey vessel

Pipeline installation vessel

Dive support vessel

Guard vessel In is anticipated that installation of the flowlines will commence in January 2013 and will be undertaken within a five month window. Tie-in of the wells will be conducted from a DSV which will use dynamic positioning (DP) to keep station.

5.2.3.2 Subsea tie-in

Production wells Wells will be tied back to the manifold and into the main export flowlines through flexible jumpers and drop down spools. The jumpers and spool pieces will be pre-filled with monoethylene glycol (MEG), surface laid and connected at each end. The MEG is typically dyed with RX-9022 at a concentration of 100mgl-1. Typically five dye sticks, such as Dyestick RX-9034A (which weigh 50g), will be placed in the spool pieces to assist with leak detection. The chemicals introduced into the spool pieces will remain in the flowline until the well comes on to production. They will then be exported to the FPSO with produced oil where they will enter the production train and eventually be re-injected with produced water. The chemical cores in the new sections of control umbilical will be pre-filled onshore with the fields control fluid; Castrol Transaqua HT2 or an equivalent control fluid. On start-up of the production wells it will be pushed out of the chemical cores and into the production flowline, from where it will be produced back to the FPSO with first oil. As Castrol Transaqua HT2 is a water based control fluid, it is expected to partition into the water phase and will be re- injected with produced water. Once the spool pieces are connected, they will be leak tested. MEG dyed with RX-9022, at a concentration of 100mgl-1 will be pumped into the spool pieces to increase the pressure in the line. Once test pressure is established the pressure will be released by discharging the fluids. The chemicals used during leak testing will be introduced and discharged from the DSV.

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Water injection wells The water injection flexible jumpers and drop down spools will be pre-filled onshore with potable water inhibited with RX-9022 at a concentration of 100mgl-1 and RX-5227 at a concentration of 500mgl-1. They will then be surface laid and connected at each end. The RX-9022, RX-5227 and potable water will remain in the flowline until the well comes into use. They will then be injected into the well ahead of the injection water. Typically three dye sticks, such as Dyestick RX-9034A dye sticks, will be placed in the spool pieces to assist with leak detection. Typically, half a dye stick per flange will be used. These dye sticks will also be injected into the well will the fluids in the flowlines at well start-up and will not be discharged to sea. The chemical cores in the new sections of control umbilical will be pre-filled onshore with the fields control fluid; Castrol Transaqua HT2. On start-up of the well it will be used to function test the xmas tree valves. The Castrol Transaqua HT2 (or equivalent control fluid) will eventually be discharged to sea during normal tree valve operations. Once the jumpers and spool pieces are connected, they will be leak tested. Leak testing will involve pumping seawater dyed with RX-9022 (at a concentration of 100mgl-1) and RX-5227 (at a concentration of 500mgl-1) into the spool pieces to increase the pressure. Once test pressure is established the pressure will be released by discharging the fluids. The chemicals used during leak testing will be introduced and discharged from the DSV. Chemicals typically used during installation and leak testing are provided in Appendix B. These may change in future, but all proposed chemical use and discharge will be finalised in the PON15C chemical permit for each flowline as required under the Offshore Chemical (Amendment) Regulations 2011.

5.2.3.3 Manifold

Two tie-in spools will be required, one for each flowline, at the FPSO where the flowline connects to the risers. A 6 slot manifold will be required for the production well centre to the south and will be approximately 6m x 5m x 3m (tall) and weigh 100 tonnes. The manifold will be a gravity based structure, held in place with additional ballast units.

5.2.3.4 Protection

Subsea structures All subsea structures will be of a fishing friendly design, of the type approved by the Scottish Fishermen’s Federation (SFF). Such structures typically feature raked sides that are designed to lift trawl wires and gear up and over, significantly reducing the risk of snagging. Horizontal xmas trees will be used for the well heads. They have a relatively low profile and allow the manufacturer to offer a protection structure integral with the tree frame and including deflection members. It is assumed that the trees will be provided with an integrated protection frame and that the conductor has been cemented such that it provides adequate resistance to fishing interaction loads. A conductor/riser analysis will be performed to confirm the

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wellhead is able to withstand the predicted snag loading from fishing activity in the area. To provide cathodic corrosion protection, sacrificial anodes will be attached to the structures. The volume, composition and location of the anodes will be determined during detailed design. Anodes are an aluminium zinc indium alloy, typical specifications for which are given in Table 5-3. Anodes vary in weight and are designed to provide protection to the flowline for 10 years. Table 5-3: Sacrificial anode composition Chemical Composition (% by weight) Cadmium 0.002 (maximum) Copper 0.005 (maximum) Indium 0.016 - 0.030 Iron 0.09 (maximum) Silicon 0.10 (maximum) Zinc 4 - 6 Others (each) 0.02 (maximum) Aluminium Remainder

Flowline physical protection The production flowlines may be protected along their length as well as between the wellheads and the manifold by concrete mattresses. Concrete mattresses consist of hexagonal concrete elements linked together with high strength non-degradable polypropylene rope, approximately 6m by 3m in dimension and 300mm thick. Divers will position these over exposed jumper lines, spools and flowlines. Grout bags may be used at smaller exposed areas, typically at joins between mattresses and close by to any subsea installations. The manifold will be within 100m of the wellheads and all jumpers/spool pieces will be within a 10m corridor from the wellheads to the manifold. It is also likely that the first 50m of the flowlines, control umbilical and power cable will be mattressed. At the production centre the flowline corridor will be 50m. At the water-injector centre the flowline corridor will be 30m. In the event of any undulations in the trench (and subsequently the flowline) a contingency will be in place for the provision of approximately 5,000 tonnes of rock for deposition for protection. The rock will be deployed to mitigate any upheaval buckling or pipeline out of straightness events experienced during the trenching and pipe-lay activities. This may be required for pipeline protection, depth of cover anomalies or dropped object protection. The requirement for rock deposition will be identified during post lay survey and if required the rock will be placed accurately utilising a dynamically positioned fall pipe rock installation vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot location.

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5.3 PRODUCTION OPERATIONS

As discussed in Section 3-1, current estimates are that the Alma field will produce a maximum of 32.5 MMbbls of crude oil and 8.1 Bscf of gas. The gas to oil ratio is assumed to be 250 scf per barrel. Wells are expected to have a high water cut and will be produced with the aid of ESP’s. Reservoir pressures will be maintained by produced water reinjection supplemented with treated seawater. The FPSO will support all production activities with crude oil offloading every two weeks. Field life is anticipated to be approximately ten years.

5.3.1 Produced Fluids Offloading

It is anticipated that a shuttle tanker will visit the FPSO initially once every two weeks to offload stored crude oil. During offloading operations the offloading hose is suspended in a free-hanging catenary configuration between the FPSO stern and the bow of the shuttle tanker. Between offloading operations, the free end of the offloading hose is hung-off from a support platform at the FPSO stern (Figure 5-8). The shuttle tanker has a maximum offloading capacity of 100,000m3 (87,000 tonnes). Figure 5-8: Offloading from Uisge Gorm FPSO

Source: www.oilrig-photos.com/picture/number115.asp

5.3.2 Power Generation

The FPSO will have its original three 0.9MW rated diesel engines and two new 14MW steam boilers. The steam boilers can be fuelled by diesel (fuel oil), fuel gas or crude oil. Under normal operations gas produced from the reservoir will be used to power the steam boilers. However, as gas production declines over field life there will be insufficient gas produced to power both and eventually even one of the steam boilers. When gas production proves insufficient to power a boiler it will switch to duel fuel e.g., fuel gas and crude oil will be burnt at the same time. As the boilers will run on gas augmented by crude, only excess gas will be flared, however there may be a short period during the early

REPORT REF: P1459BA_RN2525_REV0 5-16 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

part of field life where excess gas is produced that cannot be burned, this will be flared. At the peak of production it is anticipated that gas production will be in the order of 7 mmscf/d (198,200m3/d). For the steam boilers there will be a waste heat recovery scheme in place. Waste heat will be recycled back into the boilers and turned into steam. This means less waste heat is vented to the atmosphere. The diesel engines will be used primarily during start-up when the flow of produced gas is insufficient to run the steam boilers. Once the steam boilers are operational the diesel engines will be switched off and only used during maintenance. The steam boilers are typically 86% thermal efficient and operate at low pressures. This means that emissions of NOx are typically low. Reservoir hydrocarbons at Alma have low sulphur content and therefore SOx emissions will also be low.

Figure 5-9 shows the monthly cumulative CO2 emissions from the installed capacity of the three 0.9MW diesel generators and one 1.5MW steam driven turbo generator on the Uisge Gorm from January 2008 to August 2008 (only data available at time of EIA preparation). The monthly CO2 emissions are well below permitted levels, with a total of 28,018 tonnes of CO2 having been generated by the end of August 2008.

Figure 5-9: Cumulative total CO2 (tonnes) from Uisge Gorm FPSO (Jan-Aug 2008)

Source: Bluewater

5.3.3 Gas Flaring

The flare system provides the facilities to safely collect and dispose of normal and/or emergency hydrocarbon liquid and gas releases from all areas of the process plant. The system is designed to handle all flaring situations that could occur and to meet all the relevant environmental and safety criteria. As discussed in Section 5.3.2 above, the vast majority of produced gas will be used for power generation. It is expected that gas will only be flared in an emergency situation. There will be no flaring as a part of well clean-up.

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Over 8.138 Bscf (230.4 million m3) will be produced from the Alma Development. Of this, 7.88 Bscf (223 million m3) will be used as fuel gas for power generation on the FPSO and it is anticipated that no more than 258,500 scf (7,320m3) will be flared. Consent to flare under the Petroleum Act 1998 will be applied for approximately three to four months before start-up. This will cover any flaring during commissioning, start-up and production. Additionally, flaring activity will be considered in applying for an allowance under the EU Emissions Trading Scheme (EU ETS).

5.3.4 Chemical Use

A number of chemicals will be required during production operations. Initial chemical injection facilities are expected to be:

Topsides corrosion inhibitor

Topsides scale inhibitor

Seawater biocide

Oxygen scavenger

Demulsifier

Antifoam

De-oiler

Subsea scale inhibitor

Subsea hydraulic control fluid Chemicals will either be dosed into injection water or supplied to the wells through the chemical umbilical. The quantities required will be calculated based upon production flows, temperatures and pressures. All chemical use will be permitted under an Offshore Chemical (Amendment) Regulations 2011 chemical permit i.e., PON15D. The majority of chemicals will be within a closed system with no discharge to sea; however some chemicals such as control fluids may be discharged at the wellheads. These permitted discharges will be risk assessed.

5.3.5 Produced Water (PW)

Under normal operations all PW will be re-injected with treated seawater into the water injection wells. The PW system has been designed to handle up to 140,000bwpd (22,260m3/d). Production forecasts suggest that the field will produce approximately 120,000bbls (19,000m3) of fluids per day. At the start of field life the water / oil ratio will be approximately 70% e.g., 30bbls of oil and 70bbls of water for every 100bbls of total produced fluids. As the reservoir declines the water / oil ratio will increase and by the end the oil water ratio will be 95% water and 5% oil (5bbls of oil for every 95bbls of water). However, throughout field life 120,000bwpd will need to be injected to maintain the reservoir pressure and balance. Any shortfall between the volume of PW extracted and the volume to be injected will be made up with treated seawater. The PW system has been designed to achieve, as a minimum, oil in water (OIW) concentrations of 30mgl-1. Historically, the Uisge Gorm was regularly

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achieving OIW concentrations of <15mgl-1 on the Flora and Fife fields (including Angus and Fergus). EnQuest are committed to a performance standard of <30mgl-1 for all PW injected so that if the system trips there is the option to discharge PW overboard. On arriving at the FPSO produced fluids are routed through two first stage separators. Oil from the first stage separators is passed on to a second stage separator / coalescer and routed to the cargo tanks. Water comes out of the first and second stage separators and is routed through a bank of hydrocyclones. Each separator has its own dedicated bank of hydrocyclones which typically reduce the OIW concentrations in the PW from 1000mgl-1 to <30 mgl-1. From the hydrocyclones the PW is routed through one of two degasser / settling vessels. It is not expected that much settling will occur, but the vessel can be used to increase residency times should the system trip and PW requires further processing. PW is passed from the degasser/settling vessels to a PW pump and on to one of four water injection pumps that pump the PW into the water injection flowline and through to the water injection wells. The overboard discharge valve sits between the PW pump and the water injection pump. The FPSO will also have a separate, but connected seawater system. Seawater is de-aerated and treated with biocide before passing through one of two booster pumps and onwards through one of two water injection pumps. The seawater is co-mingled with the PW after the PW system water injection pumps before the water enters the water injection flowline. The seawater system booster pumps and the PW system PW pumps are connected. This ensures that during planned maintenance one pump out of the six can be switched off but the combined systems can still manage throughput, with no overboard discharges necessary. It is possible that PW may be discharged if one of the pumps fails. During this scenario, PW will be discharged overboard until the pump is bought back online or until throughput is reduced to a level where the pump is not necessary. The maximum overboard discharge would be 20,000bwpd (3,180m3) rather than the full production quantities, because without the reinjection system working reservoir pressure cannot be maintained and the wells will stop flowing. OIW concentrations in overboard discharges would be less than 30 mgl-1.

5.3.6 Sewage Treatment and Drainage

The FPSO was built in 1985 and does not have a sewage treatment plant. All sewage and food waste is macerated before being discharged overboard. Bluewater have not found a practical method of updating the system that delivers a substantially better environmental performance. All fluids entering the drain system are routed to the slops treatment system, processed through the produced water system and re-injected with the produced water.

5.4 DECOMMISSIONING

Field life is estimated to be ten years and therefore abandonment will occur around 2033. The arrangements for decommissioning of the subsea facilities and flowlines have been development in accordance with the current UK

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Government legislation and international agreements in force. The decommissioning plan is based on the following assumptions:

Plug and abandon all wells

Removal of the conductor to below the mud line

Removal of the subsea xmas trees

Removal of the manifold

De-oil and remove the two production flowlines

Remove the water injection flowline

Remove the power cables and control umbilicals

Remove and relocate the FPSO

Third party confirmation of seabed clearance A pigging loop has been included in the two production flowlines so they may be joined together at the drill centre location. To de-oil the flowlines, a pipeline chemical pig will be pushed down the first flowline from the FPSO around the loop and up the second production flowline. The pig will push any oil remaining in the flowline in to the processing facilities on the FPSO.

5.5 PROJECT ACTIVITY SUMMARY

In conclusion, certain aspects of the project activities described in the above sections have the potential to interact with the environment. These project aspects are detailed in Table 5-4 below and their interaction with each environmental receptor have been assessed in Sections 7 to 9. Table 5-4: Summary of project activities and aspects Project Activity Project Aspects Construction Safety exclusion zones Anchoring Exhaust gas emissions Physical presence and movement of vessels Discharge of sewage, grey water, food waste and drainage water Subsea noise Physical presence and movement of vessels Increased vessel activity in region Bulk storage and transfer Dust release during transfer Subsea noise Discharge of cuttings Drilling of wells Discharge of chemicals (including WBM) Discharge of reservoir hydrocarbons Subsea noise Physical presence of subsea infrastructure and flowlines Installation of flowlines Trenching and backfill Discharge of chemicals Concrete mattressing and rock placement

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Project Activity Project Aspects Construction Anchoring Installation of FPSO Subsea noise Production Exhaust gas emissions from power generation and gas flaring Discharge of produced water Physical presence, operation and Discharge of chemicals maintenance of FPSO Subsea noise Safety exclusion zones Physical presence and movement of export Exhaust gas emissions tanker and supply vessels Increased vessel activity in region Presence of flowlines Presence of subsea infrastructure and flowlines Accidental Events Overboard loss of equipment or waste Dropped objects Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon release (1-10 tonnes) Diesel, crude or chemical spill (including OBMs) Chemical / hydrocarbon release (>10 tonnes)

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6 PROJECT FOOTPRINT

This section, as for the project description, is presented in two main parts: Construction and Production operations. For each stage a quantitative, where possible, and qualitative summary of the environmental footprint on the project on the following key environmental receptors is provided:

Atmosphere

Water resources

Seabed The project footprint includes the physical presence of the project on the surrounding environment (e.g., anchor scars and flowline trenching on the seabed) and emissions to air and water (e.g., greenhouse gas emissions to the atmosphere, chemical and wastewater discharges to sea and noise pollution to air and sea).

6.1 CONSTRUCTION

6.1.1 Atmosphere

6.1.1.1 Exhaust gas emissions

During construction, a number of vessels and aircraft will be used for a variety of construction activities. Each vessel/helicopter will generate atmospheric emissions from the combustion of fuel. Estimated emissions are summarised in Table 6-1. Estimates for vessels are based on the maximum number of days vessels will be on-site and the worst-case fuel use in that period. Table 6-1: Construction exhaust gas emissions Activity Vessel Types Total Fuel Total Emissions (tonnes) Duration Use (days) (tonnes) CO2 CO NOx N2O CH4 VOC SOx Drilling rig 447 4,470 14,304 35.76 263.73 0.98 12.07 10.73 8.94 Standby vessel 447 2,235 7,152 17.88 131.87 0.49 6.03 5.36 4.47 Drilling Supply boat 112 1,120 3,584 8.96 66.08 0.25 3.02 2.69 2.24 Anchor handling 112 2,800 8,960 22.40 165.20 0.62 7.56 6.72 5.60 Helicopter 112 165 528 0.86 2.06 0.04 0.01 0.13 0.33 Flowline installation vessel 70 1,400 4,480 11.20 82.60 0.31 3.78 3.36 2.80 Flowlines Guard vessel 164 820 2,624 6.56 48.38 0.18 2.21 1.97 1.64 Diving support vessel 93 1,860 5,952 14.88 109.74 0.41 5.02 4.46 3.72 Total - 1,557 14,870 47,584 118.5 869.66 3.28 39.7 35.42 29.74 Source: Emissions factors taken from Table 15 UKOOA (2002)

6.1.1.2 Airborne noise

Few data sources are available for airborne noise levels offshore. It is acknowledged that wave and surf noises are important contributors. It is expected that ambient noise levels will be in the region of 72 to 90dB (re 1μPa) (Richardson et al. 1995).

REPORT REF: P1459BA_RN2525_REV0 6-1 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Airborne impulsive and continuous noise will be generated during all phases of construction. Impulsive noise is generally made up from sounds short in duration with obvious start and finish points, typically with durations of less than 0.5 seconds. Examples include noise from air guns or percussion piling. Continuous noise has no obvious start and finish points, such as that caused by drilling. Furthermore, the duration of the noise can be transient (duration is typically in the order of seconds to weeks) or long-term (the order of magnitude is typically months or years). The potential airborne noise sources from construction are summarised in Table 6-2. Table 6-2: Summary of construction noise sources and activities Activity Source Frequency Duration Propellers and bow and stern Manoeuvring of semi-submersible rig Continuous thrusters Deployment and adjustment of anchors Winches and anchor chains Occasional Maintenance of rig on location Short-term Pipe laying vessel, trenching vessel (days, Installation of flowlines and support weeks) Diver and ROV installation of subsea Continuous Subsea Installation spools, protective structures, piling and concrete mattressing Transport (equipment and personnel) Helicopters and support vessels Regular Medium- term Drilling Machinery noise Continuous (months)

Airborne sound propagation is affected by the proximity of the sound source to the ground or sea level. Vertical propagation is influenced by reflections and wave transmissions across the surface and wind refraction and temperature gradients which produce poor sound transmission in the upwind direction and enhances sound transmission downwind. Although airborne noise is an important issue the main receptor affected are humans. The impacts on human health are best addressed through occupational health assessments, mitigation, and regulations and are outside the scope of this EIA.

6.1.2 Water Resources

6.1.2.1 Chemical discharges

Wells The chemicals discharged during the drilling programme are relatively benign, the majority being risk assessed by the Centre for Environment, Fisheries and Aquaculture Sciences (CEFAS) as hazard quotient (HQ) colour band Gold or Offshore Chemical Notification Scheme (OCNS) category E. These are categories for products that present the lowest hazard to the environment. Furthermore, the majority of the category E chemicals have been classed by OSPAR as posing little or no risk (PLONOR) to the marine environment. A small minority of chemicals will be discharged that have a higher HQ (i.e., a lower environmental profile) or that have been marked as candidates for substitution (SUB) as they contain components that have high toxicity, low biodegradation and/or potential for bioaccumulation. Chemical use will be

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minimised where operationally possible and all discharges risk-assessed via the PON15B process. The OSPAR decision 2000/3 prevents the discharge of OBM to the marine environment and therefore all OBM fluids will be skipped and shipped for thermal processing onshore. A summary of the chemicals to be used and discharged during one well is presented in Table 6-3. It is expected that for all wells in the field development the chemical programme will be similar. An estimate of the maximum quantity of chemicals to be discharged for the eight wells is presented in Table 6-4. Table 6-3: Summary of chemical discharges (tonnes) – One well Drilling: WBM System Drilling: OBM System Cementing Completion & Other

Use Discharge Use Discharge Use Discharge Use Discharge A 0 0 8 0 0 0 0 0 B 0 0 116 0 0 0 0 0 C 0 0 49 0 0 0 4 1 HQ D 0 0 42 0 0 0 12 12 E 1256 1,256 3,574 0 2,062 1,130 7,650 6,872 Gold 48 48 51 0 110 60 128 128 Silver 2 2 0 0 0 0 12 2 PLO 1,244 1,244 1,959 0 1,822 1,004 6,879 6,870 Label SUB 8 8 253 0 26 13 54 42 Total 2,558 2,558 6,052 0 4,020 2,207 14,739 13,927

Table 6-4: Summary of chemical discharges (tonnes) – Eight wells Drilling: WBM System Drilling: OBM System Cementing Completion & Other

Use Discharge Use Discharge Use Discharge Use Discharge A 0 0 64 0 0 0 0 0 B 0 0 928 0 0 0 0 0 C 0 0 392 0 0 0 32 8 HQ D 0 0 336 0 0 0 96 96 E 10,048 10,048 28,592 0 16,496 9,040 61,200 54,976 Gold 384 384 408 0 880 480 1,024 1,024 Silver 16 16 0 0 0 0 96 16 PLO 9,952 9,952 15,672 0 14,576 8,032 55,032 54,960 Label SUB 64 64 2,024 0 208 104 432 336 Total 20,464 20,464 48,416 0 32,160 17,656 117,912 111,416

Flowlines As discussed in Section 5.2.3.1 chemicals will be discharged to sea during various stages in the flowline installation and commissioning. A summary of the intended discharge quantities from the three flowlines are provided in Table 6-5. Examples of the types and quantities of chemicals to be used are provided in Appendix B. These are subject to change and exact details will be provided in the PON15C for each flowline as required under the Offshore Chemical (Amendment) Regulations 2011.

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Table 6-5: Summary of flowline discharges 2x Production Flowlines Water injection Flowline Chemical Activity Estimated Estimated Estimated Use Estimated Type Use (kg) Discharge (kg) (kg) Discharge (kg) Flooding RX-9022 27.12 4.52 21.24 3.54 RX-5227 135.6 22.6 106.2 17.7 Hydro-testing RX-9022 4.52 4.52 3.54 3.54 RX-5227 22.6 22.6 17.7 17.7 Leak-testing RX-9022 4.52 4.52 3.54 3.54 RX-5227 22.6 22.6 17.7 17.7 Commissioning RX-9022 0 22.6 0 0* RX-5227 0 113 0 0* * Volumes remaining in the flowline will be injected into the wellbore on start-up of well. Well Tie-in As discussed in Section 5.2.3.1 chemicals will be discharged to sea during various stages in the tie-in of the production and water injection wells. A summary of the intended discharge quantities are provided in Table 6-6. Examples of the types and quantities of chemicals to be used are provided in Appendix C. These are subject to change and exact details will be provided in the PON15C for each well as required under the Offshore Chemical (Amendment) Regulations 2011. Table 6-6: Summary of discharges from well tie-in Use (onshore Use (offshore) Discharge Fate Chemical Name pre-fill) (kg) (kg) (kg) 6 x Production wells Castrol Transaqua HT2 165.12 0 165.12 Discharged at seabed DYESTICK RX-9034A 0 1.5 1.5 Discharged via FPSO process system Discharged via FPSO process system MEG 4692 2671.2 7363.2 or discharged at sea surface from DSV Discharged via FPSO process system RX-9022 0.432 6.36 6.792 or discharged at sea surface from DSV 2 x Water injection wells Castrol Transaqua HT2 38.16 0 38.16 Discharged at seabed DYESTICK RX-9034A 0 0.3 0 Injected into well on start-up Injected into well on start or discharged RX-5227 0.35 6.87 6.87 at sea surface from DSV Injected into well on start or discharged RX-9022 0.07 2.12 2.12 at sea surface from DSV

6.1.2.2 Waste water

During the field development it is likely that construction vessels and the drilling rig will discharge grey water (from washing and laundry facilities etc) and sewage. Table 6-7 gives an estimation of these discharges. Sewage discharge from the drilling rig undergoes some treatment prior to release. This can vary from fine screen maceration to full enzyme degradation. Discharges from construction vessels will undergo the level of treatment required by shipping

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regulations. The estimations provided assume all construction vessels will discharge grey water and sewage to sea (worst-case). In practice, most construction vessels will be on site for a limited period and it is more likely that they will retain any waste onboard and unload it in port.

Table 6-7: Total waste water discharge (m3) during construction Construction Vessels Duration Grey water Sewage Total waste Activity (days)1 (m3) 2 (m3) 2 water (m3) Drilling of wells Drilling rig, standby vessel, anchor 1,118 8,266 3,857 12,123 handling tug, supply boat Flowline Flowline installation vessel, survey 327 3,570 1,666 5,236 installation vessel, diver support vessel Total - 1,445 11,836 5,523 17,359 1 Not all vessels will be present for entire duration of each activity. Figure given is combined maximum number of days vessel will be present on site 2 Estimates based on 150 litres of grey water per person per day and 70 litres of sewage/black water per person per day.

6.1.2.3 Underwater noise

As discussed in Section 6.1.1.3, there are a number of potential sound sources during construction activities. The characteristics of underwater noises expected to be produced during the development are shown in Table 6-8. Sound is attenuated as it propagates through the water. The local oceanographic conditions will affect both the path of the sound into the water column and how much sound is transmitted. The main environmental receptors affected by underwater noise are fish and marine mammals. Sections 8.3 and 8.5 include an assessment on the disturbance ranges created by the source activities listed below. Table 6-8: Summary of underwater noise produced during construction activities Source Sound Pressure Levels (SPL) of underwater noise * (dB re 1 µPa @ 1m) (predominant frequency if known) Median Ambient Level 80 to 100 (1 - > 30,000 Hz) Drilling from rig 120 to 130 Tug / Barge 140 to 170 Piling 222 Supply / Support Vessel 160 to 170 (100 to 1,000Hz) Helicopters at various altitudes 101 to 109** * Most data taken from 1/3-octave band centre frequencies (50-2000Hz) ** Measured at the water surface Source: WDCS (2004), Richardson et al. (1995)

6.1.2.4 Safety exclusion zones

A 500m safety exclusion zone will be established around the drilling rig to ensure the safety of the vessel during drilling. This will exclude vessels from 0.78km2 of sea for the duration of the drilling period i.e., 447 days. There is no formal safety exclusion zone around a flowline installation. However, fishing vessels will be asked to keep 500m away from the flowline on

REPORT REF: P1459BA_RN2525_REV0 6-5 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

either side during installation. EnQuest expects this operation to take approximately 70 days and will take place during the first quarter of 2013.

6.1.3 Seabed Conditions

6.1.3.1 Anchoring

Drilling rig The drilling rig will maintain its position over the drill centres with eight 12 tonne anchors in an established anchor pattern within a 1,500m radius. When anchors are lifted clear the anchor fluke levers sediment onto the seabed creating either a mound or an area of disturbed seabed. The size of the mound is dependent on the seabed characteristics. Anchor mounds are common where seabed sediments or shallow sub-surface sediments are composed of clay. Section 8 illustrates that sediments within the Alma field comprise a thin layer of sand over sandy gravelly clay, which will be conducive to the creation of anchor mounds. Sidescan sonar images of the region (GGL 2011) clearly show disturbed areas of seabed, possibly associated with anchor pull out from previous drilling campaigns and more than likely from the Argyll/Ardmore field decommissioning. It is therefore likely that up to eight anchor mounds will be left on the seabed at each drill centre during the proposed development. Each anchor will have an impact area of approximately 25m2 and therefore, the total area of seabed impacted by all 16 anchor mounds from construction activities has been estimated at 400m2 (Table 6-11). The anchors will be attached to the drilling rig with a chain and cable combination. Approximately 300m of chain will be in contact with the seabed. This will provide additional anchoring hold, but will also create gouges and scar marks as the chains move under wind and tidal influence. Based on the assumption that the each anchor will create a 300m scar it has been calculated that the scarring will affect 4,800m2 of seabed (Table 6-11). FPSO The FPSO will be held permanently on station using nine mooring lines, configured into three clusters. Engineering is currently underway to establish the arrangements for securing to the sea bed. Depending on the outcome the anchor chains will be secured to the seabed with either a piled anchor or a drag anchor, e.g. a Vryhof or Strevpris type anchor. It is not envisaged that the FPSO anchor chains will impact on the seabed.

6.1.3.2 Drill cuttings

Cuttings generated from the drilling of the top two sections of each well will be discharged directly to the seabed. All other WBM cuttings will be discharged 1m to 10m below sea level from the drilling rig. OBM cuttings will be skipped and shipped to shore. Table 6-9 summarises the weight of cuttings to be generated from each well and the discharge manner. Exact cuttings weights will be provided in individual PON15Bs for the wells.

REPORT REF: P1459BA_RN2525_REV0 6-6 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Table 6-9: Weight and discharge fate of drill cuttings (tonnes) Well Discharged to seabed Discharged 1m below Skipped and shipped sea level Northern Drill Centre 5,472 2,208 1,860 (producers x 6) Southern Drill Centre 1,824 736 620 (water injectors x2) Total 7,296 2,944 2,480

Cuttings piles Cuttings discharged directly on to the seabed will form a deposition pile around the wellhead. Under conditions of low current speed it is assumed that this pile would form in the shape of a cone, with a slope angle of 18° (i.e., a height-to- radius ratio of 1:3; the cone will be six times wider than it is high). This assumption is based on the physical properties of sand. However, it is likely that bottom currents will rapidly re-suspend and mobilise the cuttings, spreading them over a larger area. In addition, as the associated WBM dissolves, the cuttings will lose cohesion and spread out. With this in mind the extent of a cuttings pile, still assuming it will take the shape of a cone, has been calculated for a range of slope angles. Figure 6-1 illustrates that for a cuttings discharge of 442m3 (912 tonnes; i.e., one well) the cuttings pile is likely to have a maximum footprint on the seabed of 2,627m² (if slope is 1°). In reality, the footprint is likely to be in the region of 374m² (if slope is 18°) per cuttings pile. As a worst case scenario it is assumed that drill cuttings piles (within their respective drill centres) will not overlap for either spatial or temporal reasons. The worst case total seabed footprint from all drill cuttings piles (16 in total) is therefore 21,016m2 (if slope is 1°) or 2,992m2 (if slope is 18°). In reality, though as the wellheads are within 15m of each other, it is expected that the cuttings piles (within their respective drill centres) will overlap, reducing the area of impact.

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Figure 6-1: Area of seabed covered by 1 well cuttings pile

3000

2500

2000 ) 2

1500 Area (m 1000

500

0 0° 2° 4° 6° 8° 10° 12° 14° 16° 18° 20° Slope Angle

Cuttings dispersion If WBM is used then cuttings from the 17½" section will be discharged 1m below the sea surface from the drilling rig. Cuttings will be dispersed over a wider area of seabed as currents transport them away from the discharge point. The pattern of drill cuttings deposition from the rig is expected to be similar to that experienced from other wells drilled in the CNS. Cuttings are deposited in an elliptical orientation along the major axis of current flow (generally NE in the CNS). Deposition of cuttings over a thickness of 1mm is generally confined to within 500m of the discharge location (UKOOA 1999).

6.1.3.3 Flowlines

Table 6-10 summarises the footprint on the seabed as a result of the flowline installation. Table 6-10: Summary of flowline installation footprint on the seabed Activity Comments Length (m) Width (m) Number Footprint on seabed (m2) Base Case - Water injection flowline is trenched and production flowlines are surface laid Flowline initiation Two 13 ½ tonne initiation anchors used 5 4 6 120 Trenching Width given is estimated Water injection 2,500 2 1 5,000 corridor of impact including flowline profile of trench, any spoil Water injection 2,500 2 1 5,000 piles and disturbed area in umbilical between Power cable 2,500 2 1 5,000 Surface laid Production 3,000 0.2032 2 1,219 Production umbilical 3,000 0.1026 1 308 Concrete - 6 3 310 5,580 mattressing

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Activity Comments Length (m) Width (m) Number Footprint on seabed (m2) Rock placement Total length based on volume of rock used 600 6 - 3,600 (5,000 tonnes) Total - - - - 25,827 Option 2 - All flowlines are surface laid Flowline initiation Two 13 ½ tonne initiation anchors used per 5 4 6 120 flowline Flowline installation Production 3,000 0.2032 2 1,219 Production umbilical 3,000 0.1026 1 308 Water injection 2,500 0.2032 1 508 Water injection umbilical 2,500 0.1026 1 257 Power cable 2,500 0.1016 1 254 Concrete - 6 3 310 5,580 mattressing Total - - - - 8,246

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6.1.3.4 Summary of all seabed footprints

As discussed in the section above, during construction there will be a number of activities which will impact the seabed. These are summarised in Table 6-11. Table 6-11: Summary of seabed footprint - field development Aspect Length (m) Width (m) Height / Number Footprint on depth seabed (m2) (m) Construction Drilling rig anchor mounds and chain 300 - - 16 4,800 scars(8 per drill centre) Drilling rig anchor chain scars (8 per drill - - - 16 400 centre) Well Head 9 9 6 8 648 Manifold 6 5 3 2 60 Drill cuttings pile - 374 - 8 2,992 Sub-total 11,892 Flowlines – Base case Flowline initiation anchors 5 4 - 6 120 Trenching Water injection flowline 2,500 2 1 2 10,000 and umbilical Power cable 2,500 2 1 1 5,000 Surface Production 3,000 0.2032 - 2 1,219 laid Production umbilical 3,000 0.1026 - 1 308 Concrete mattresses 6 3 - 310 5,580 Rock placement 600 6 1 - 3,600 Sub-total 25,827 Flowlines – Option 2 Flowline initiation anchor 5 4 - 6 120 Flowlines 13,500 Variable - 6 2,546 Concrete mattresses 6 3 - 310 5,580 Sub-total 8,246 Development Footprint – Base case 37,719 Development footprint – Option 2 20,138

REPORT REF: P1459BA_RN2525_REV0 6-10 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

6.2 PRODUCTION

6.2.1 Atmosphere

6.2.1.1 Power generation

As discussed in Section 5.3.2, three 0.9MW rated diesel engines and two 14MW steam boilers onboard the FPSO will be used to meet all power requirements. The main power demand for Alma will come from the ESPs, water injection, plus the base load for remaining process equipment and domestic requirements. Emissions per annum, presented in Table 6-12, have been calculated based on technical specifications provided by the engineering contractor and the manufacturer of the generators. Calculations assume the steam boilers will work at full load for the year and the diesel generators will run for approximately 500 hours per year (5% of the year) and are based on the exhaust emissions at full power under ISO (International Standards Organisation) conditions i.e., 15°C, 60% relative humidity and sea level pressure of 101.3kPa. Table 6-12: Emissions from power generation Emission factors (per tonne fuel burnt) Emissions per annum (tonnes) Gases 2x Steam boiler 3x Diesel Steam boiler Diesel generator Total Gas Crude Marine diesel generator

NOx 0.0024 0.0594 0.249 0.306 0.290 5.4 6.245 CO 0.0006 0.0157 0.063 0.077 0.073 1.43 1.643 VOC 0.0000099 0.002 0.002 0.002 0.002 0.19 0.196

SO2 0.0000128 0.004 0.002 0.002 0.002 3.72 3.726

CO2 2.77 3.2 286.62 352.32 334.12 290.03 1263.09 Note: Emissions for diesel generators calculated from Uisge Gorm FPSO PPC permit application and assume that all three generators will run for approximately 500 hours per year (5% of the year). Standard default emission factors as used in the UK Environmental Emissions Monitoring Scheme (EEMS) have been used and are taken from Table 8.2 in Root-5 Ltd (2004)

Emissions of CO2 from power generation depend on two things: 1) Carbon content of the fuel 2) Efficiency of converting fuel to useful energy Specifications for the generators show that at full power and under ISO -1 conditions they will produce 16.36kgh of CO2 per MWh when burning gas, -1 -1 20.11kgh of CO2 per MWh when burning crude and 19.07kgh of CO2 when burning diesel. Table 6-13 shows the CO2 emissions from the different fuel type for the year.

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Table 6-13: CO2 emissions for the steam boiler from power generation Fuel Type Emissions per hour (kg) Emissions per annum (tonnes) Gas 16.36 143.31 Crude oil 20.11 176.16 Diesel 19.07 167.05

6.2.1.2 Flaring

As discussed in Section 5.3.3, it will be necessary to flare gas for a short period during the early part of field life where excess gas is produced that cannot be burned, and also in an emergency situation. There will be no flaring as a part of well clean-up. Over 8.138 Bscf (230.4 million m3) will be produced from the Alma Development. Of this, 7.88 Bscf (223 million m3) will be used as fuel gas for power generation on the FPSO and it is anticipated that no more than 258,500 scf will be flared. In the absence of data from a monitoring system, the default emission factors used in the Environmental Emissions Monitoring Scheme have been used to calculate the emission gases from flaring. These are presented in Table 6-14 below. A maximum worst case estimate of 7 mmscfd-1 gas flared at the start of field life has been used for the calculation. Table 6-14: Flaring gas emissions during production Emission Emission Factor Gas Gas Emissions (tonne emission/ tonne gas burned) (tonnes)

CO2 2.8 428.15 CO 0.0067 1.02 NOx 0.0012 0.18

N2O 0.000081 0.01

SO2 0.0000128 0.002 CH4 0.045 6.88 VOC 0.005 0.76

6.2.1.3 Emissions from vessels

Routine visits to the FPSO will be carried out via helicopters and ships during the life of the Alma development. There will also be routine visits to the FPSO from the export tanker. Emissions per annum for these visits are presented in Table 6-15.

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Table 6-15: Production - vessel exhaust gas emissions Activity Vessel Duration Total Fuel Total Emissions (tonnes) Types (days) Use CO2 CO NOx N2O CH4 VOC SOx (tonnes) Supply, Supply maintenance and vessel and 144 551 1,763 4.2 29.2 0.1 1.3 1.2 1.1 crew change visits helicopters Offloading of crude Export tanker 24 240 768 1.9 14.2 0.1 0.7 0.6 0.5 oil Enforcement of 500m safety Guard vessel 365 1,825 5,840 14.6 108 0.4 5.0 4.4 3.7 exclusion zone Total - 533 2,616 8,371 20.7 151.4 0.6 7 6.2 5.3 Source: Emissions factors taken from Table 15 UKOOA (2002)

6.2.1.4 Airborne noise

The potential sound sources from production are summarised in Table 6-14. The majority of the noise levels will be above sea level and so it is expected little sound above the ambient levels already generated during operation will be transmitted into the water column. The development will not significantly increase the levels of vessel activity in the region during production. Table 6-16: Summary of production noise sources and activities Activity Source Source type Duration Power generation Turbines and generators Continuous Permanent (years) Transport (equipment and Helicopters and supply Continuous Transient (days) personnel) vessels Offloading of crude oil Export tanker Continuous Transient (days)

6.2.2 Water Resources

6.2.2.1 Produced water (PW)

Under normal operations, all PW will be re-injected into the water injection wells to ensure reservoir pressure is maintained. If one of the pumps trips then there is the possibility that PW will need to be discharged overboard until either the pump is brought back online or the throughput flow is reduced. The maximum overboard discharge in this instance would be 120,000bbls/d (19,080m3/d). The system onboard the FPSO will clean up the produced water to less than 30mgl-1. When the FPSO was in service on the Flora and Fife fields (including Angus and Fergus fields) it was achieving oil in water (OIW) concentrations of <15mgl-1 regularly. On Alma all produced water will be processed to achieve a performance standard of at least 30mgl-1 so if the water re-injection system trips and is unavailable, then the PW can be discharged overboard. A maximum of 95.4kg/day of oil would be discharged in one trip (at 30mgl-1 in 20,000bbls of PW) as it is unlikely that a trip would last all day. However, given the previous recorded OIW discharge of the FPSO this is more likely to be in the region of 47.7kg of oil (at 15mgl-1 in 20,000 bbls).

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6.2.2.2 Drainage and waste water

During the life of field development it is likely that visiting vessels and the FPSO will discharge grey water (from washing and laundry facilities etc) and sewage. Table 6-15 gives an estimation of these discharges. Sewage discharge from the FPSO will undergo some treatment prior to release. All sewage and food waste is macerated before being discharged overboard. Discharges from visiting vessels will undergo the level of treatment required by shipping regulations. The estimations provided assume all visiting vessels will discharge grey water and sewage to sea (worst-case). In practice, most vessels will be on site for a limited period and it is more likely that they will retain any waste onboard and unload it in port. Table 6-17: Total waste water discharge per annum for field life Activity Vessels Duration Grey water Sewage (m3) 2 Total waste (days)1 (m3) 2 water (m3) Supply, crew Export tanker 24 108 50 158 change, offloading, Supply vessel 48 216 101 317 maintenance1 Guard vessel 365 657 307 964 Day to day FPSO 365 5,475 2,555 8,030 activities Total - 365 6,456 3,013 9,469 2 Estimates based on 150 litres of grey water per person per day and 70 litres of sewage/black water per person per day.

6.2.2.3 Chemical discharges

Chemicals to be used for well maintenance during the operational life of the field are given in Table 6-16. All chemicals injected for well maintenance will be in a closed system with no discharge to sea. A water-based subsea hydraulic control fluid will be supplied through the control umbilicals from the FPSO to the control wellhead valves on the xmas trees. The system operates as an open-loop system (industry standard). This means that small amounts of control fluid are discharged near the seabed from the directional control valves when they are opened and closed. The typical discharge from the eight wellheads will be a total of 24m3 to sea per year. The main properties required of a hydraulic control fluid are low viscosity, low compressibility, corrosion protection, resistance to microbiological attack, compatibility with seawater and biodegradability. Full details of all chemical use and discharge required for the production phase will be confirmed in an application for a PON15D permit prior to start-up at Alma; however it is more than likely that the hydraulic fluid will be Castrol Transaqua HT2. EnQuest Heather Limited considers the minimisation of chemical usage a priority and will actively seek products that are deemed to have minimal environmental impacts (i.e., low toxicity, low bioaccumulation potential and high biodegradability). There is unlikely to be any long term change in the chemical composition of the surrounding water column as a result of the discharge of chemicals during oil and gas operations. Consequently, it is considered that the impact on water resources is likely to be minimal.

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Table 6-18: Alma chemical injection requirements Chemical Name Chemical Type Injection Point Injection Rate (mgl-1) Subsea Gyptron SA Scale Inhibitor Subsea flowlines 20 Methanol Hydrate Inhibitor Subsea flowlines As required Oil Process System Emulsotron DE5710 Demulsifier Production header 10 Cortron RN537 Corrosion Inhibitor Topsides/Oil production 40 flowline Produced Water Cleartron KZB 281 Deoiler Ex 1ststage separator 10 Boiler System OS3 Oxygen Scavenger Boiler feed water 10 Caustic Soda Alkalinity Builder Boiler feed water 10 Water Injection System OS2 Oxygen Scavenger De-aerator tail pumps 20 Sodium Hypochlorite Biocide Discharge S/W lift pumps 20 Bactron B2090 Biocide De-aerator tail pumps 500 (twice weekly for 2 hours) Defoamer AF400 Anti Foamer Upstream de-aerator tower 15 Utilities Liquidewt Corrosion Inhibitor Closed cooling medium and As Required heating water Slops Tanks Bactron B2090 Biocide Slops tank 500 Closed Drains Bactron B2090 Biocide Closed drains 250

6.2.2.4 Underwater noise

Underwater noise from the FPSO will be dominated by the noise produced by the onboard power generators. The noise produced by the power generation for the Alma development is expected to be minimal when compared to overall noise levels in the CNS.

6.2.2.5 Safety exclusion zones

A 500m safety exclusion zone will be in place around FPSO at all times. This will exclude vessels from 0.78km2 of sea for the duration of the field life (ten years).

6.2.3 Seabed Conditions

No additional seabed disturbance is anticipated during production activities.

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7 ACCIDENTAL EVENTS

Accidental events are incidents or non-routine events that have the potential to trigger impacts that would otherwise not be anticipated during the normal course of construction, operation or decommissioning. The severity of impact from accidental events can be greater those from routine operations, however the probability of an accidental event occurring is typically much lower. Given the high potential severity of accidental events, they require plans specifically designed to respond to the event as quickly and effectively as possible. In addition to mobilising the operator’s resources, additional resources from external parties such as government agencies are often an inherent part of the incident response. EnQuest will submit an oil pollution emergency plan (OPEP) to the DECC Offshore Inspectorate for approval to cover the drilling and production activities at the Alma Field. The OPEP will comply with the requirements of The Offshore Installations (Emergency Pollution Control) Regulations 2002 and The Merchant Shipping (Oil Pollution Preparedness, Response Cooperation Convention) Regulations 1998 and take into consideration recent revised guidance from the DECC following the Gulf of Mexico Macondo incident. For the purpose of this assessment, the following accidental events have been considered:

Hydrocarbon spills / leaks

Chemical spills / leaks

Dropped objects Accidental releases of produced hydrocarbons from identified potential worst case spill scenarios have been assessed and modelling studies carried out to characterise the extent of the impact. These results are presented in Section 7.3 and Appendix B.

7.1 TYPES OF ACCIDENTAL EVENT

7.1.1 Hydrocarbon Spills and Leaks

The characteristics of liquid hydrocarbons used and produced during the project phases are summarised below. These include diesel, lubricating and hydraulic oils, crude oil and aviation fuel. Spills and leaks of gas and condensate have not been considered below because both liquids are non-toxic and, as they vaporise quickly, they will have a minimal impact on the marine environment in the unlikely event of a spill. Crude Oil There is a small chance that a crude oil spill could occur in association with the Alma development due to:

A collision causing loss of inventory from the FPSO and/or the export tanker

Loss of inventory from the export flowlines due to a rupture or incident such as fishing damage

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Accidental releases of produced hydrocarbons from identified potential sources have been assessed and modelling of the relevant scenarios carried out to characterise the extent of the impact (see Section 7.3). The scenario modelled was if the FPSO and export tanker collided resulting in the total loss of inventory from both vessels. Neither vessel would be full to capacity at the same time in the same location, so as the export tanker has the largest capacity (100,000m3, 87,000 tonnes) this was the total amount modelled. The Alma crude has an API of about 38° and modelling shows that it is likely to emulsify, with an expected water content of 80%. The most recent UK guidance on oil pollution emergency response requires Operators to model a loss of well control (blow out), as this although an extremely rare occurrence in the UK is considered to be the worst case volume of crude oil that could be spilt from a development. After consultation with the DECC Offshore Inspectorate this modelling has not be run for the Alma development due to the low reservoir pressure. From the very start of field life, reservoir pressure is such that ESPs will be required to pump crude oil out of the reservoir. In the event that well control is lost the wells will effectively self- kill. Instead, the worst case crude spill was considered to be if the FPSO and export tanker collided, with a total loss of containment. As neither vessel is likely to be full at the same time, the larger inventory of the two (export tanker) has been modelled. The modelling results are presented in Section 7.3 and Appendix B. Diesel Marine diesel used in mobile drilling rigs and support vessels is a low viscosity distillate fuel. Diesel contains a high proportion of lighter hydrocarbons, such that evaporation is an important process contributing to the removal of spilt diesel from the sea surface. Evaporation will be enhanced by higher wind speeds and warmer sea and air temperatures. The general behaviour of diesel at sea can be summarised as follows:

A slick of diesel will elongate rapidly in the direction of the prevailing wind and waves.

Very rapid spreading of the low viscosity diesel will take place.

Some diesel fuel oils may form an unstable emulsion at the thicker, leading edges of the slick.

Speed of physical dispersion of the surface slick increases with wind speed. Up to 95 % of a slick may disperse within about 4 hours of the spill in 15 knot winds and sea conditions. Only the worst case spill scenarios for the greatest inventory of diesel offshore for the development have been modelled. This would be from the FPSO and export tanker colliding into each other during offloading. The combined inventory of the two vessels has been modelled and the results are shown in Section 7.3. Lubricating and Hydraulic Oil Lubricating oils behave in a manner similar to marine diesel but are more viscous, slowing down the spread of the slick marginally. As lubricating oils are considerably refined, they do not contain the same quantity or ratio of light-end hydrocarbons. Hydraulic oils are medium oils of light to moderate viscosity.

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They have a rapid spreading rate and generally dissipate quickly, particularly in higher sea states. Lubricating and hydraulic oils are used in a variety of equipment on both drilling rigs and support vessels and are stored in containers ranging from 20 to 1,000 litres. Aviation Fuel Aviation fuel is volatile and evaporates and spreads quickly. Since the fuel will mostly evaporate, leaving little or no visible mass left on the surface within 24 hours, it is unlikely there would be sufficient time for clean-up operations in the event of a spill. Aviation fuel is used for refuelling helicopters that will transport equipment and personnel to and from the drilling rig and other offshore vessels to shore.

7.1.2 Chemical Spills and Leaks

During the life of the project there is the potential for chemical spills and leaks to occur. Spills may result in localised impacts on water quality and toxicity effects on marine fauna and flora. Chemical spills include accidental leakage of hydraulic fluid or chemical inhibitors used in the wells or accidental release of chemicals during transfer between vessels. All chemicals used during construction and production will be permitted under the Offshore Chemical (Amendment) Regulations 2011 (OCR). Chemicals that are to be discharged undergo a risk assessment. A comprehensive list of chemicals will be developed during the detailed engineering phase of the project. Bulk chemicals stored during the commissioning and operational phase of the project that are considered in this section are:

Chemical used during the drilling of the wells e.g. oil and water based drilling muds, cement chemicals, completion chemicals, rig wash, hydraulics fluids etc

Chemicals used during production e.g., wax inhibitor, asphaltene / demulsifier, scale inhibitor, methanol or MEG, corrosion inhibitor etc Specific effects on individual receptors would depend upon the type and volume of chemical released but is broadly similar to the receptors discussed in relation to hydrocarbon spills.

7.1.3 Dropped Objects

Dropped objects have the potential to increase the project footprint on the seabed if the objects are not recovered. They also pose a risk to other sea users as snagging hazards, can get caught in propellers or are a collision risk. Occurrences of dropped objects are most likely during drilling activities and during vessel transfer operations. Subsea equipment associated with the Alma development will be subject to dropped object studies to ensure that the potential risks posed by dropped objects are reduced. Dropped objects that cannot be retrieved, will be reported to the DECC on a PON2 form so that other sea users can be notified of their presence.

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7.2 PROBABILITY OF ACCIDENTAL EVENTS OCCURRING

Typically the likelihood of accidental events occurring is minimised through legislation governing the industry, emergency shut-down procedures and multiple control and mitigation measures consistent with industry best practice across the project life cycle. Events are possible during both the construction and production phase. The most frequently expected type of spill would be a small (<1 tonne) spill of oil or chemical from the rig or FPSO during bulk transfer to/from the facilities, leakage or during use or storage. Three possible incidents have been identified within the project scope as potential sources for a major spill of hydrocarbons (>100 tonnes). These are considered to be the worst case scenarios possible:

1) Loss of diesel inventory from the FPSO and tanker through collision – 2,400m3 (2,016 tonnes) from the FPSO and 3,430m3 (2,881 tonnes) from the export tanker 2) Loss of crude oil inventory from the FPSO and tanker through collision – A maximum of 94,500m3 (81,0901 tonnes) from the FPSO and a maximum of 100,000m3 (87,000 tonnes) from the export tanker (note: neither vessel will be full at the same time) 3) Loss of diesel inventory from the drilling rig – 1,665m3 (1,399 tonnes) The probability of an extensive release of hydrocarbons occurring on this project, during construction and/or production, has been assessed below.

7.2.1 Construction and drilling

Historical spill data in the UK is collated by both the DECC and the Maritime and Coastguard Agency (MCA). The DECC collates incident reports from offshore oil and gas installations, including drilling rigs, whereas the MCA collates incident reports from UK vessels, including those associated with support and construction activities for the oil and gas industry. The MCA data also incorporates data reported to the DECC to provide an overview of all marine incidents. Both sets of data have been used in the analysis below during the 20 month Alma construction period, during which the following vessel activity is envisaged:

Drilling rig – 447 days

Standby vessel to support rig – 447 days

Anchor handling vessel – 112 days

Vessels for flowline installation – combined total of 70 days on site

112 visits by supply vessels over 16 months The spill risk associated with these activities can be divided into two main categories: a) Offshore support vessels (e.g., standby, construction and supply vessels) b) Drilling rig

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Available data from the MCA (ACOPS reports) has been reviewed for years 2000 to 2009 (ACOPS 2001-2010) to establish the probability of a spill occurring from an offshore support vessel (category a) above). However, there are only two reported incidents which suggests, there is either little reported data for construction related incidents or the percentage of incidents is very low. Given the lack of data, an estimation of the likelihood of a spill from a support vessel occurring per annum would not be statistically valid. Historic data held by the DECC are more descriptive and can be used to establish the probability of a spill during drilling operations (category b) above). Records for spills from mobile drilling units have been analysed for the period 2003 to 2007. Excluding very small spills (<0.1 tonnes), data for this period shows there were 32 spills from drilling rigs. Of these, 26 were less than 1 tonne and one was over 10 tonnes (13.4 tonnes oil based mud in 2006). Over the same period it is estimated that there were approximately 1,100 wells drilled from mobile drilling units such that the probability of a release of greater than 0.1 tonnes is approximately 3% per well. At Alma there will be up to eight wells drilled which gives a 24% likelihood of a spill greater than 0.1 tonnes. There is not enough data for the larger spills (>10 tonnes) to estimate the likelihood of such a spill statistically although it can be inferred from the data that such spills are very rare

7.2.2 Production

During the project life cycle there is the potential for a loss of containment integrity of the oil production flowlines leading to a release of approximately 81m3 of crude oil. The report “Riser and pipeline release frequencies” by the OGP (2010) states that failures in a pipeline may occur as a result of:

Loads exceeding pipeline critical loads, usually resulting in an isolated incident

Gradual weakening of the pipeline over a period of time. The primary causes of pipeline failures are critical loads that may lead to an isolated incident include loads from trawl boards, ship anchors or subsea landslide. The second cause of pipeline failures are mechanisms which act over time include corrosion, open spans causing fatigue and buckling (OGP 2010). Table 7-1 provides the recommended pipeline failure frequencies for the UK offshore oil and gas industry based on the above potential causes. Using this table it has been calculated that the frequency of the production flowline failing in open sea is 0.00125 times per year, the frequency of it failing as a result of external damage is 0.0001275 times per year and the frequency of the risers failing is 0.0036 times per year.

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Table 7-1: Industry riser and pipelines failure frequencies Pipeline Category Failure frequency Unit Subsea pipeline: in open Well stream pipeline and other small Per 5.0 x 10-4 sea pipelines containing unprocessed fluid km/year Processed oil or gas, pipeline diameter Per 5.1 x 10-5 ≤24 inch km/year Subsea pipeline: external loads causing damage in Diameter ≤16 inch 7.9 x 10-4 Per year safety zone Per Flexible pipelines: subsea All 2.3 x 10-3 km/year Steel – diameter ≤16 inch 9.1 x 10-4 Per year Risers Flexible 6.0 x 10-3 Per year Source: OGP (2010)

7.3 OIL SPILL MODELLING

7.3.1 Construction

As discussed above, during the construction phase there is the potential for loss of containment from the drilling rig leading to a release of diesel and fuel oil. If this were to happen, a maximum of 1,665m3 (1,399 tonnes) of diesel would be released instantaneously. This release is smaller than those for production. Modelling has only been undertaken for the worst case spill scenarios, which occur during production and are presented in Section 7.3.2 below. The drilling rig will not be on location at the same time as the export tanker and FPSO and therefore the three inventories could not combine in an incident. As discussed in Section 7.1.1, in the event that well control is lost the wells will effectively self-kill and modelling of a well blow out has not been undertaken.

7.3.2 Production

During production from Alma the worst case scenario is for full loss of containment from both the FPSO and export tanker due to collision (with each other). If this were to happen, a maximum of 5,830m3 (4,897 tonnes) of diesel and 100,000m3 (87,000 tonnes) of crude oil would be released instantaneously. The 100,000m3 of crude oil represents the maximum (larger) capacity of the export tanker as neither vessel will be full at the same time. Modelling was commissioned to determine the extent of the spill should a collision occur. The results are presented below and in more detail in Appendix B. It should be noted that all modelling information provided is generic and illustrative only and not intended to be relied upon in any specific instance. This is because in practice any number of variables may impact on an oil spill or other environmental incident and as such should be addressed on an individual basis, taking account of the specific conditions encountered.

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The scenario was modelled using two types of models: Stochastic - A stochastic model, also known as a probability model shows the probability of where an oil spill may impact for defined periods of time for a range of prevailing wind directions. The model uses historical wind data to run a series of trajectories for the various wind directions. It then combines the results to produce an overall illustration of the probability of where oil might travel to in the defined period of time. This type of modelling is an important tool for determining the areas of coastline that could potentially be affected by a spill and therefore the best locations to place oil spill response equipment. However, this type of diagram is typically the most misunderstood part of an Environmental Statement or Oil Pollution Emergency Plan. The most important thing to note is that it does not illustrate the extent of an oil spill should a collision occur. Trajectory - A trajectory or deterministic model are used to predict the route of an oil slick over time and under certain metocean conditions. UK legislation requires two trajectory models are undertaken for each spill scenario investigated by the oil and gas industry; one trajectory using a 30 knot wind blowing towards the nearest stretch of UK coastline; and one trajectory using a 30 knot wind blowing towards the closest international boundary. Figure 7-1 shows the output of the stochastic model for the instantaneous loss of the 100,000m3 of crude oil from the export tanker. The model output illustrates the extent of the oil spill after 417 days for 12 prevailing wind directions and provides the probability of the spill reaching a particular area. For example, if during the collision the prevailing wind direction was towards the west-north-west, the diagram illustrates that there is a less than 10% probability of oil beaching on the west coast of the Shetland Islands. In this scenario, the probability of the oil also beaching in Norway would be significantly less, probably around 0%. Therefore, depending on the prevailing wind condition at the time of the event there is a 1% chance of oil beaching along the coastlines of the majority of countries bordering the North Sea (Figure 7-1 and 7-2). Modelling indicates that the spill will have beached on the UK coastline within 8 days and 10 hours and on the Danish coastline within 5 days and 12 hours. The spill will have completed dispersed within 417 days.

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Figure 7-1: Stochastic model run – 100,000m3 instantaneous spill of 38° API crude oil (417 days)

Source: Adapted from OSR (2011) Figure 7-2: Possible beaching locations

Source: OSR (2011)

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For a worst case diesel spill, the probability of any beaching occurring is close to zero. The stochastic modelling shows that after 10 hours, all spilt diesel has either evaporated or has been dispersed (Figure 7-3) (OSR 2011).

Figure 7-3: Stochastic model run – 5,830m3 instantaneous spill of diesel

Source: Adapted from OSR (2011)

For the purposes of oil spill response planning EnQuest are required to model, using the trajectory method, the fate of the worst case spill scenarios during conditions when:

A 30 knot wind would blow the spill directly to the UK coastline

A 30 knot wind would blow the spill directly towards the closest international boundary This type of modelling can provide a guide as to where a spill may beach and what volumes of oil may reach the coastline. Trajectory modelling (Figures 7-4 and 7-5) indicates that with a 30 knot wind towards the earliest point of impact on the UK coast, approximately 86,393m3 of crude oil would beach approximately 200 hours after the incident along the North Yorkshire coastline (OSR 2011). In 30 knot wind conditions towards the nearest international boundary, crude oil would head towards the UK / Norwegian median line, crossing it within 5 hours of the incident occurring. On this trajectory it would continue towards the Norwegian and Danish coastlines, crossing the Norway / Denmark median line after 31 hours and potentially beaching on the Danish coast in approximately 130 hours. The volume of oil emulsion beaching is estimated to be 161,742m3 (OSR 2011).

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Figures 7-6 and 7-7 show that in either scenario (onshore/offshore), no diesel will beach on any coastline. All diesel will either be evaporated or dispersed within 10 hours of the spill occurring. Figure 7-4: Spill trajectory under 30 knot wind conditions towards the UK coastline

Source: OSR (2011) Figure 7-5: Spill trajectory under 30 knot wind conditions towards the nearest international boundary

Source: OSR (2011)

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Figure 7-6: Diesel spill trajectory under 30 knot wind conditions towards the UK coastline

Source: OSR (2011) Figure 7-7: Diesel spill trajectory under 30 knot wind conditions towards the nearest international boundary

Source: OSR (2011)

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8 IMPACTS ON PHYSICAL ENVIRONMENT

In order to understand the potential impacts from a development on the environment, it is fundamental to have a clear understanding of the present state of the environmental baseline. For the purposes of this report the environment has been split into three categories: physical, biological and human. This section covers the physical environment and has been organised to describe the following in the order below:

Describe the data sources used

Present baseline conditions for the environment

Identify potential impacts from the Alma development on the environment

Propose mitigation measures to curtail, limit or eliminate potential impacts

Assess the significance of the residual impacts if mitigation measures are implemented The physical environment has been divided into the following areas:

Air (Section 8.1)

Climate change (Section 8.2)

Water resources (Section 8.3)

Seabed conditions (Section 8.4) Gardline Geosurvey Limited (GGL) was commissioned to carry out geophysical and geotechnical rig site and pipeline route survey investigations (GGL 2011) in the Alma development area. This survey also incorporated an environmental baseline and habitats component (GEL 2011), to obtain location specific information. These surveys were used to inform the majority of Section 8, 9 and 10. Other data sources used are recorded at the beginning of each section.

8.1 AIR

8.1.1 Baseline Data Sources

The main sources of data for this section are:

UK National Air Quality Archive. http://uk-air.defra.gov.uk/ (UK National Air Quality Archive 2011)

UK Air Quality Archive – Background NOx, NO2, PM10 and PM2.5 Maps for LAQM and DMRB. http://laqm.defra.gov.uk/maps/maps2008.html (UK National Air Quality Archive 2009)

Met Office European model (56.0°N 3.14°E Jan 1998 - Nov 2008). Data acquired under licence for this project (Met Office 2011).

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8.1.2 Existing Baseline

Air quality An understanding of the existing air quality in the project area is useful when assessing the potential future impact upon air quality from the proposed operations.

In general, UK air quality has been improving since 1990. Emissions of NOx and SO2 have decreased by 46% and 82% respectively due to reduced emissions from road transport and power stations (Dore et al. 2008). Data on offshore air quality is limited due to the absence of air quality monitoring stations. However, the gases are generally of limited concern in the offshore sector given the distances to sensitive receptors i.e. communities on land or fixed installation. The Alma development is, at its closest 274km from land and 40.5km from the nearest fixed installation (northern drill centre to Clyde platform). Levels of primary pollutants, which are emitted directly into the atmosphere, tend to be highest around their sources i.e., in urban and industrial areas. Simple dispersion modelling undertaken for a 90 day exploration well in the Southern North Sea (SNS) (Gaz de France Britain 2005) demonstrated 3 3 concentrations of NOx and SO2 would be 0.0139 µg.m and 0.0009 µg.m respectively at 500m from the emission point, well below health and environmental guidelines. The modelling assumed that 15 tonnes of fuel would be consumed per day from the drilling rig and standby vessel. The CNS, in which the Alma field development is located, is generally considered to be windier than the SNS and therefore it was considered that this modelling could be applied to the field development. Wind regime The wind regime affects the dispersion of atmospheric emissions and the trajectory of surface films. It generates the wave regime which contributes to the dispersion of discharges at the sea surface (and in extreme storms can contribute to dispersion at the seafloor). An understanding of the wind regime is therefore important in understanding the potential for aerial and aquatic dispersion of emissions and discharges from the development, oil spill trajectory forecasting and planning of wind-sensitive elements of oil spill response. A wind rose for the development area showing the annual prevailing wind directions is presented in Figure 8-1. Table 8-1 presents the corresponding percentage frequency distribution of wind speed (Beaufort Force) versus direction (30° sectors centred on the cardinal points). Wind direction shows a wide distribution; the prevailing direction is south-westerly and winds from the northeast are comparatively uncommon. The strongest winds generally come from the sector southwest through to north. The data have been extracted from the UK Met Office European Model; purchased under licence for use on this project.

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Table 8-1: Annual wind percentage frequency distribution at standard height (10m) Force knots m/s 0° 30° 60° 90° 120° 150° 180° 210° 240° 270° 300° 330° %

0 0 0-0.2 ------0.3- 1 1 - 3 1.5 0.23 0.17 0.16 0.17 0.25 0.19 0.23 0.22 0.28 0.17 0.27 0.23 2.58 1.6- 2 4 - 6 3.3 0.50 0.44 0.41 0.54 0.54 0.63 0.66 0.61 0.65 0.61 0.67 0.63 6.91 3.4- 3 7 - 10 5.4 0.98 0.96 0.91 1.08 1.26 1.38 1.47 1.72 1.70 1.57 1.44 1.29 15.76 11 - 5.5- 4 16 7.9 1.89 1.28 1.25 1.51 2.01 2.40 2.89 3.29 3.44 3.17 3.20 2.74 29.08 17 - 8.0- 5 21 10.7 1.31 0.61 0.78 1.09 1.54 1.42 1.85 2.57 2.59 2.27 2.25 2.75 21.03 22 - 10.8- 6 27 13.8 0.85 0.29 0.30 0.55 1.30 0.98 1.22 2.08 2.52 1.87 1.63 1.94 15.54 28 - 13.9- 7 33 17.1 0.27 0.06 0.09 0.18 0.48 0.27 0.48 1.15 1.14 0.95 0.67 0.88 6.61 34 - 17.2- 8 40 20.7 0.07 0.02 0.01 0.02 0.13 0.10 0.12 0.42 0.37 0.37 0.24 0.26 2.12 41 - 20.8- 9 47 24.4 0.01 - - 0.00 0.01 0.00 0.03 0.03 0.09 0.08 0.03 0.03 0.31 48 - 24.5- 10 55 28.4 0.00 ------0.00 0.02 0.01 0.02 0.00 0.05 56 - 28.5- 11 63 32.6 ------0.00 - - - 0.00

12 64 + 32.7+ ------

Total 6.11 3.82 3.92 5.15 7.53 7.38 8.95 12.10 12.80 11.07 10.43 10.75 100.00 Source: Met Office European model at 56.0°N 3.14°E Jan 1998 - Nov 2008. Data acquired under licence for this project

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Figure 8-1: Annual wind rose for the Alma area

000° (30) 330° 030° (25)

(20)

(15) 300° 060° (10)

(5)

(0)

Calms 270° 090° 0%

240° 120°

210° 150°

180°

Mean Wind Speed (knots) 1-16 11 - 21 17 - 27 22 - 33 28 - 40 34 - 47 41 - 55 48 - 63 56 - 10 7 - 3 1 - 6 4 - 64 +

Notes: 1. Source: Met Office European Model obtained under licence for the client 2. Location: 56.0°N, 3.14°E 3. Period: Jan 1998 - Nov 2008 4. 1 knot = 0.515 m/s 5. Wind speeds represent 1-hourly means referenced to a standard height of 10 m above sea level 6. Percentage calm or variable data is indicated in centre of rose

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8.1.3 Potential Impact Identification

This EIA has identified that during the project life cycle the activities listed in Table 8-2 have the potential to impact on air quality. Table 8-2: Air quality – potential impact identification Project Activity Aspect Potential impact Construction Physical presence and movement Exhaust gas emissions of vessels Localised deterioration in air quality Bulk storage and transfer Dust release during transfer Production Physical presence, operation and maintenance of FPSO Localised deterioration in air Physical presence and movement of Exhaust gas emissions export tanker and supply vessels quality Flaring during initial stages of production

All of these aspects have a potential to deteriorate site specific (i.e., within the project area) air quality for a very short period of time, although the change to the baseline will be of minor/negligible significance. The likelihood, spatial extent, frequency, duration, sensitivity, recoverability and significance of the potential impacts have been assessed in Section A of Appendix A2 and A3.

8.1.4 Mitigation Measures

EnQuest and any contractors will undertake practical steps to minimise atmospheric emissions. These include, but are not limited to:

Ensuring efficient operations by keeping all power generation equipment well maintained

Using cleaner lower emission fuels and monitoring fuel consumption

Stack heights will be in accordance with the relevant regulations

The emissions associated with power generation will be managed via a new Pollution Prevention Control (PPC) permit that will be applied for before production commences.

EnQuest are committed to keeping production flaring to the minimum required for operational purposes. 8.1.5 Residual Impact Significance Assessment

8.1.5.1 Localised deterioration in air quality

Emissions of CO2, oxides of nitrogen (NOx), and oxides of sulphur (SOx) will result from power generation from the drilling rig and FPSO, vessels associated with the development and flaring during production. After implementation of the mitigation measures, approximately 870 tonnes of NOx and 30 tonnes of SOx will be emitted to the atmosphere during construction (Section 6.1.1.1). 6.3 tonnes of NOx and 3.8 tonnes of SO2 will be emitted during production from the FPSO (Section 6.2.1.1). From a worst case estimate of 7 mmscfd-1 gas flared at

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the start of field life, 0.01 tonnes of NOx and 0.002 tonnes of SO2 will be emitted.

Emissions of SOx and NOx are known contributors to degradation of regional and local air quality. The European Commission has set threshold/limit values for NOx and SOx concentrations in ambient air to improve the protection of human health and the environment. For NOx the alert threshold is 500 parts -3 -3 per billion (ppb) (400μgm ) and for SOx the alert threshold is 30 ppb (80μgm ) if smoke concentrations are greater than 34μgm-3 (Dore et al. 2008). However, the gases are of limited concern in the offshore sector given the distance to sensitive receptors i.e., communities on land or other fixed installations.

Given the generally dynamic offshore, concentrations of NOx and SOx are not expected to reach European Commission alert thresholds and there is expected to be no residual impacts on regional air quality.

8.2 CLIMATE CHANGE

8.2.1 Baseline Data Sources

This section principally references the following secondary data sources:

UK Policy Planning Statement 25: Development and Flood Risk. Revised March 2010 (CLG 2010).

UK Climate Projections website (http://ukclimateprojections.defra.gov.uk) (2009)

UK Climate Impacts Programme website (http://www.ukcip.org.uk/) (2011) To help organisations to assess their vulnerability to climate change and plan appropriate adaptation strategies the UK Government established the UK Climate Impacts Programme (UKCIP). The programme established scenarios for future climate change in the UK, taking in to consideration current and future mitigation measures to be implemented by UK Government. These scenarios have been used to predict what the future environmental baseline at the Alma development will be as the environment responds to climate change.

8.2.2 Existing Baseline

There is an increasing body of evidence showing that global climate is changing as a consequence of human actions. Past, present and future emissions of greenhouse gases are expected to cause significant global climate change during the next century. Sea level will continue to rise, having implications for wave heights, wave propagation, storm events, flooding and coastal erosion. Sea temperatures, salinity and nutrient levels may also rise with implications for biological processes. The magnitude of sea level rise is dependent on greenhouse gas emissions, the sensitivity of the climate system and the relative local vertical movement of the surrounding land masses. The UK land mass is generally falling in the south-east and rising in the north and west. The UK climate projections predict an absolute sea level rise of between 2.8mm and 3.8mm per year for the period of 1990 to 2025 and between 6.1mm and 8.1mm per year for the period of 2025 to 2055, for UK marine areas (UKCP 2009). In addition, Table 8-3 below shows

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the recommended contingency allowances for net sea level rise from 1990 until 2115 (CLG 2010). Table 8-3: Recommended contingency allowances for net sea level rise Net Sea Level Rise (mm/yr) Relative to 1990 Administrative Region 1990 to 2025 2025 to 2055 2055 to 2085 2085 to 2115 East of England, East Midlands, London, South East England (south of Flamborough 4.0 8.5 12.0 15.0 Head) South West 3.5 8.0 11.5 14.5 North West England, North East England 2.5 7.0 10.0 13.0 (north of Flamborough Head) Notes: 1. For deriving sea levels up to 2025, the 4mm/yr, 3mm/yr and 2.5mm/yr rates (covering the three groups of administrative Regions respectively), should be applied back to the 1990 base sea level year. From 2026 to 2055, the increase in sea level in this period is derived by adding the number of years on from 2025 (to 2055), multiplied by the respective rate shown in the table. Subsequent time periods 2056-2085 and 2086-2115 are treated similarly. 2. Refer to Defra FCDPAG3 Economic Appraisal Supplementary Note to Operating Authorities – Climate Change Impacts, October 2006, for details of the derivation of this table. In particular, Annex A1 of this Note shows examples of how to calculate sea level rise. 3. Vertical movement of the land is incorporated in the table and does not need to be calculated separately. Source: CLG 2010 Table B.1

It is predicted that a rise in sea level will change wave heights due to increased water depths, and may change the frequency, duration and severity of storm events. The Government suggests that a 5% sensitivity allowance should be added to offshore wind speeds and wave heights by 2025 (CLG 2010). Sea temperatures in the NNS may rise by 1.0°C by the 2020s and by 1.5 - 3.0°C by the 2080s (under low and high emissions scenarios respectively) (UKCIP 2002). The UK climate predictions for the period 2070 – 2099 indicate that the mean sea surface water temperature will be between 8°C and 17.0°C in the project area (UKCP 2009).

8.2.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities presented in Table 8-4 have the potential to contribute greenhouse gases to the atmosphere. Table 8-4: Climate change – potential impact identification Project Activity Aspect Potential Impact Construction Physical presence and movement of Exhaust gas Loading of greenhouse gases e.g., vessels emissions CO2, CH4 Production Physical presence, operation and Exhaust gas Loading of greenhouse gases e.g., maintenance of FPSO emissions CO2, CH4 Physical presence and movement of export tanker and supply vessels Flaring during initial stages of production

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These aspects all have the same potential impact in that they could lead to loading of greenhouse gases, increasing the rate or magnitude of climate change. The EIA concluded that the potential impact would affect the wider environment, but would be of low severity and short duration. However, overall the likelihood of the impact occurring is considered to be unlikely. The assessment is provided in Sections B of Appendix A2 and A3.

8.2.4 Mitigation Measures

The key atmospheric emissions that contribute to climate change are CH4 and CO2. Measures to reduce atmospheric emissions were discussed under the air quality section (Section 8.1.4). The same measures will be instrumental in addressing emissions of CH4 and CO2. In addition, EnQuest are committed to ensuring the minimum amount of gas is flared during production. Emissions associated with power generation will be managed via an EU ETS permit Alma will utilise the majority of the produced gas from the field to meet the production power requirements of the FPSO and therefore production flaring (and associated emissions) will be kept to a minimum.

8.2.5 Residual Impact Significance Assessment

Approximately 47,585 tonnes of CO2 will be emitted during construction (Section 6.1.1). CO2 emissions from power generation during production are expected to be approximately 1,263 tonnes per year, with an additional 428 tonnes being emitted during gas flaring at the start of field life. Approximately 8,371 tonnes of CO2 per year are expected to be emitted by vessels conducting routine visits to the development. Overall it estimated that the development will emit 96,768 tonnes of CO2 over field life (ten years) (Section 6.2.1). It is generally acknowledged that CO2 emissions contribute to global warming and climate change and are therefore considered a global issue. To assess the potential impact of the project emissions on climate change they have been considered in the context of the UK’s global contribution. Records of offshore CO2 emissions from UK oil and gas installations (fixed and mobile) for the year 2009 were obtained from the DECC (OGUK 2009). Data from subsequent years is not yet in the public domain. For comparison purposes, data has been split between emissions from drilling rigs and emissions during production (from FPSOs and platforms). The 2009 data shows that 35 drilling rigs were mobilised in UK waters during the year. CO2 emissions from diesel consumption ranged from 232 tonnes to 20,116 tonnes, averaging 7,252 tonnes per rig. Figures calculated in Section 6 for the proposed Alma development have been adjusted to allow comparison against annual figures. From Table 8- 5 it can be seen that the projected CO2 emissions do not represent a significant proportion of the UK offshore emissions (a total of 0.97% of UK emissions during construction and 0.012% during production) and therefore are not considered significant. Both figures are relatively small contributions to annual UK emissions and are typical for a standard oil development of this size.

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Table 8-5: Comparison of UK and Alma CO2 emissions - Annual

Development Emission source Alma CO2 UK Offshore O&G CO2 Comparison: stage emissions emissions (tonnes) percentage of (tonnes) UK Construction Drilling Diesel 14,304 253,8071 5.64% consumption Construction Diesel 33,281 4,675,000 2 0.72% vessels consumption Total - 47,585 4,928,807 0.97% Production Gas, fuel oil and 1,263 11,864,9491 0.011% Production diesel consumption Gas flaring 428 3,122,5801 0.014%

Total - 1,691 14,987,529 0.012% Notes: 1 OGUK (2009) 2 Figure for 2006 emissions for English international shipping (Thomas and Thistlethwaite 2008) The EIA has concluded that the project will not be a significant contributor to global warming and there will be no residual impact.

8.3 WATER RESOURCES

8.3.1 Baseline Data Sources

This section principally references the following secondary data sources:

nd 2 Strategic Environmental Assessment (SEA) technical reports including information on water quality (DTI 2001a,b)

Quality Status Report (OSPAR Commission 2010)

EnQuest (2010). Ardmore Redevelopment Basis of Design. Document No. KNI-PM-000-BOD-0002 Revision A1 8.3.2 Existing Baseline

Mixing of North Atlantic water and freshwater run-off from land, results in several water masses occurring in the North Sea with characteristic temperature and salinity distribution, residual current patterns and stratification. The Alma field development area is situated within the CNS water mass. Density stratification is well developed in the summer months, with the relative strength of the thermocline determined by solar heat input and turbulence generated by wind and tides. It breaks down after September however, due to increasing frequency and severity of storms and seasonal cooling at the surface (DTI 2001a). Temperature and salinity characteristics in the Alma field development area are indicated in Table 8-6.

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Table 8-6: Physical characteristics of the sea water in the Alma field Water Approximate parameter value Minimum 0 º C Sea surface temperature1 Maximum 19 º C Minimum 5 º C Bottom temperature1 Maximum 9 º C Sea surface salinity2 35.048 psu Bottom salinity2 35.052 psu Source: 1 Enquest (2010) 2 Analysis of data obtained from International Council for Exploration of the Sea (http://www.ices.dk/ocean/aspx/HydChem/HydChem.aspx)

8.3.2.1 Water quality

There are many sources of contamination entering the North Sea which can affect water quality. For example, riverine inputs, coastal run-off and offshore activities. Pollutants of the water column can be separated into the following distinct areas:

Organics (including hydrocarbons)

Trace metals

Radionuclides To inform the SEA process a review of chemical contamination was undertaken by CEFAS and the Fisheries Research Service (FRS, now Marine Scotland) to identify background levels and trends in the North Sea (DTI 2001b). The review indicated that (i) inshore estuaries and (ii) coastal sites, subject to high industrial usage, show the highest levels of chemical contamination (Table 8-7, DTI 2001a). Offshore waters generally contain lower concentrations of polyaromatic hydrocarbons (PAH) and total hydrocarbons (THC). For example, PAH concentrations exceeding 1µgl-1 were found in four UK eastern coast estuaries compared to concentrations between 0.018-0.09µgl-1 offshore in the German Bight (DTI 2001b). Similarly, Law et al. (1994), in DTI 2001b) found that THC concentrations offshore are generally very low (2.5µgl-1) compared to levels found in some estuaries (64µgl-1) (DTI 2001b). High concentrations of THCs, in the range of 30 - 43µgl-1, are found in the immediate vicinity of some offshore oil and gas installations, although concentrations generally fall to background levels within a short distance from the discharge point (DTI 2001b). Table 8-7: Summary of North Sea surface waters contaminant levels THC PAH PCB Ni Cu Zn Cd Hg Location (µgl-1) (µgl-1) (ngl-1) (µgl-1) (µgl-1) (µgl-1) (ngl-1) (ngl-1) Oil & Gas Installations 1 - 30 ------Estuaries 12 - 15 >1 30 - - - - - Coast 2 0.02 - 0.1 1 - 10 0.2 - 0.9 0.3 - 0.7 0.5 - 2.2 10 - 32 0.25 - 41 Below Offshore 0.5 - 0.7 - 0.2 - 0.6 0.3 - 0.6 0.5 - 1.4 10 - 51 1.6 - 69 detection Source: DTI 2001b Historically there have been two main sources of contaminants from oil and gas activity in the North Sea: produced water and drill cuttings. With the

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introduction of OSPAR decision 2000/3, hydrocarbon input from drill cuttings has been essentially eliminated, as OBM is no longer discharged to sea. However, there is a legacy of contamination which remains, in the form of historic cuttings piles around some installations, especially in the CNS and NNS (DTI 2001b). Produced water is now the main contamination source, containing both hydrocarbons and chemicals. Historic research has shown that, due to the rapid dilution and low concentrations and low toxicities of the pollutants, produced water discharges in the North Sea have a low potential for biological impact (Wills 2000). Dilutions required for no observed effect concentration (NOEC) are achieved within five minutes between 10 to 100m from the discharge point. The nearest platform is Clyde, which is 40.5km north-west of the Alma northern drill centre, and at this range it is not conceivable that Alma would have a material impact on the area causing the NOEC to be exceeded. As a result, it is considered that as exposure times are short, acute toxic effects on species are unlikely (Wills 2000). Long term or chronic effects are also unlikely given the minimal contaminant levels in produced water (UKOOA 1999). It has been suggested that contaminants in discharges may affect planktonic larvae (Wills 2000), but more work is required by the industry on the amounts, fates and effects of toxic heavy metals in produced water before any significant conclusions can be drawn.

8.3.2.2 Tidal and other currents

Speed and direction of currents has a direct effect on the transport, dispersion and ultimate fate of any discharges into the marine environment. Strength of current determines the rate of dispersion and vertical mixing of discharges into the water column. Figure 8-2 (adapted from DTI 2001a after Turrell 1992) is a schematic diagram of general circulation in the North Sea. The broad pole-ward transport of Atlantic Water along the continental slope (the “Slope Current”) branches along the western slope of the Norwegian trench and also spills onto the continental shelf around the Shetland Islands. The approximate location of the Alma development is indicated on the diagram. At Alma, tidal current speeds are relatively high compared to other areas of the North Sea. Average speeds of 0.2ms-1 at surface indicate a flushing time of 1.5 hours for a column of water 500m in diameter. Near bed speeds are approximately half of surface speeds. Current speeds may be slower in summer. The current speeds at the Alma field are summarised in Table 8-8. Table 8-8: Summary of tidal current speeds at the Alma field Depth (m) 1 year (m/s) 50 year (m/s) 0 (surface) 0.64 0.71 8 0.59 0.65

20 0.51 0.57 40 0.48 0.53 60 0.48 0.53

78 (seabed) 0.42 0.47 Source: EnQuest (2010)

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Figure 8-2: General current circulation in the North Sea

Source: Adapted from DTI 2001a after Turrell et al. (1992)

Storm surges will also occur occasionally but are short-lived. They occur when a deep depression crosses the NNS or Norwegian Sea and manifest as a tide- like wave progressing southward through the North Sea. This temporarily increases water levels and current speeds. Storm surge currents can exceed speeds associated with tides.

8.3.2.3 Waves

The wave regime in the area contributes to initial dispersion of any surface discharges and therefore needs some consideration in the assessment of a development’s impact on the environment.

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Wave heights are among the greatest in the North Sea (100-year extreme significant wave height (Hs) is 16m and 1-year extreme is 12m) (See Table 8-9 & 8-10). The North Sea is considered to be frequently “rough” from October to March (DTI 2001a). Table 8-9: Wave characteristics at Alma Parameter 1 Year 50 Year 100 Year Hs (m) 10.3 13.8 14.4 Tz (s) 10.9 12.6 12.9 Hmax (m) 19.1 25.4 26.4 Tmax (m) 14.0 16.1 16.5 Source: EnQuest (2010) Table 8-10: Monthly wave height at Alma Month 1 Year (m) 50 Year (m) January 9.5 12.6 February 9.5 12.6 March 7.2 9.6 April 7.0 9.3 May 4.5 6.0 June 4.5 6.0 July 4.3 5.8 August 5.7 7.7 September 7.5 10.0 October 7.6 10.1 November 7.7 10.2 December 9.5 12.6 Source: EnQuest (2010)

8.3.3 Potential Impact Identification

The construction and production activities at Alma have the potential to affect water quality. Additionally, tides, currents and waves will have an indirect affect on some project aspects and their impacts on environmental receptors, e.g., by influencing the dispersion of chemical discharges. The EIA identified that during the project life cycle the activities listed in Table 8-11 have the potential to interact with water resources.

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Table 8-11: Water resources – potential impact identification Project Activity Aspect Potential Impact Construction Discharge of sewage, grey water, food Physical presence and movement of vessels waste and drainage water Bulk storage and transfer Dust release during transfer Localised deterioration in water Discharge of chemicals (including WBM) Drilling of wells quality Discharge of reservoir hydrocarbons Discharge of chemicals (including WBM) Concrete mattressing and rock placement Installation of flowlines Increased Trenching and backfill suspended sediment Physical presence of subsea loads & turbidity infrastructure and flowlines Production Discharge of produced water Localised Physical presence, operation and Discharge of chemicals deterioration in water maintenance of FPSO Discharge of sewage, grey water, food quality waste and drainage water Accidental Events Chemical / hydrocarbon release (< 1 tonne) Localised Chemical / hydrocarbon release (1-10 Diesel, crude or chemical spill (including deterioration in water tonnes) OBMs) quality Chemical / hydrocarbon release (>10 tonnes)

In general, these aspects have only two potential impacts on water resources; the potential to degrade water quality and the potential to increase suspended sediment loads and turbidity. The EIA concluded that activities have the potential to create both these impacts, generally on a site specific basis (i.e., effects restricted to the project area). Some of the accidental events assessed potentially have a much wider area of impact e.g., the local or wider region. The sensitivity of the receiving environment impacts varies from negligible to low depending on the activity but the majority of impacts are restricted to short- term effects. The assessment is provided in Sections C of Appendix A2 and A3 and Section A of Appendix A4. EnQuest Heather Limited considers the minimisation of chemical usage a priority and will actively seek products that are deemed to have minimal environmental impacts (i.e., low toxicity, low bioaccumulation potential and high biodegradability). There is unlikely to be any long term change in the chemical composition of the surrounding water column as a result of the discharge of chemicals during oil and gas operations. Consequently, it is considered that the impact on water resources is likely to be minimal.

8.3.4 Mitigation Measures

All project associated vessels will have and implement a written waste management plan compliant with the International Convention for the Prevention of Pollution from Ships (1973/1978) (MARPOL 73/78) and its Annexes. As per Regulation 9 (Annex V, 1995) all vessels over 400 tonnes will have and maintain a Garbage Record Book. The plan will establish designated

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waste storage areas and will ensure all waste is contained and stored away from open drains. All liquid waste will be stored with secondary containment. Paper and food wastes will only be discharged beyond 12nm from shore. No plastics or plastic containing materials will be disposed at sea, regardless of location. Solid wastes will be compacted where possible and stored for appropriate disposal ashore. Household products and construction chemicals (i.e., chemicals used during completion drilling and pipeline commissioning) which are environmentally benign will be preferentially selected. Chemical use will be monitored daily during construction to allow more refined and efficient use. Where possible, products will be recycled or reinjected to minimise discharge quantities. Only chemicals approved under the relevant Offshore Chemicals (Amendment) Regulations (OCR) chemical permit will be discharged, i.e., PON15B, PON15C or PON15D. As per Section 6.2.2.1, under normal operating conditions, all produced water from the Alma development will be re-injected into the water-injection wells. It is only if the system trips, that there is a possibility that produced water will be discharged overboard from the FPSO. To ensure any discharges in such a situation are regulatory compliant all produced water will be processed so that OIW concentrations are at least 30mgl-1. Accidental spills will be kept to a minimum through training, storage/handling procedures and good housekeeping. Management controls will be in place to eliminate accidental and bunkering spills e.g., only bunkering during good daylight conditions and in good weather. EnQuest will have an approved OPEP in place to mitigate against accidental hydrocarbon spills associated with the proposed drilling and production activities. These will be prepared in accordance with the Oil Pollution Preparedness, Response and Co-operation Convention Regulations 1998, the Offshore Installations (Emergency Pollution Control) Regulations 2002 and updated guidance provided by the DECC in response to the Macondo Prospect incident in the Gulf of Mexico. The impacts of hydrocarbon spills are greatest for seabirds and as such the mitigation measures for fuel and crude oil spills are discussed in detail in Section 9.4.4.

8.3.5 Residual Impact Significance Assessment

8.3.5.1 Deterioration in water quality

Taking proposed mitigation measures into consideration, the EIA concluded that there will be a no residual impact on water quality as a consequence of the discharge of chemicals or produced water (see Sections C of Appendix A2 and A3) and a minor residual impact on water quality from an accidental chemical/hydrocarbon release of >10 tonnes (Section A of Appendix A4).

8.3.5.2 Increased suspended sediment loads

Five activities during the construction phase have the potential to disturb seabed sediments, increasing suspended sediment loads in the water column. These are:

Placement of subsea infrastructure

Jet trenching the flowlines into the seabed

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Placement of flowlines on the seabed

Placement of concrete mattressing

Rock reinforcement of pipeline Although the placement of subsea infrastructure, flowlines, concrete mattresses and the rock material on the seabed will disturb the seabed, it is expected that suspended sediments will return to normal as soon as the activity ceases. Of these activities, jet trenching has the potential to create the largest disturbance. Jet trenching involves using high pressure water jets to fluidise the seabed beneath the flowlines, which disrupts the sediments, forming a trench full of fluidised material, into which the pipeline sinks under its own weight. It is estimated that approximately 1.6km of flowline will be trenched per day. As the trench backfills naturally, it is not envisaged that any of the sediment will be piled on each side of the trench. Finer fractions could become suspended in the water column, potentially increasing suspended sediment loads. The surface sediments at the development consist of <1m thickness of very loose to loose silty shelly sands (with a varying degree of gravel and shells) over firm to very stiff sandy gravelly clay. Both the sand and clay will be suspended, but only the sand is likely to settle out of suspension quickly (within a few minutes of suspension) along the route. The finer particle size of the clay (0.002 mm) will remain in suspension, potentially for days, and will be transported by currents away from the pipeline route. It will settle out, but slowly, over a wider area, ensuring a thinner deposition (possibly undetectable). Suspended sand is expected to settle in a thin layer in close proximity to the trench. Limited research has been conducted into the effects of pipeline installation on sediment loading, but a comparable impact on water quality can be found in the marine aggregate industry. Often, as marine aggregate is extracted, the water/aggregate mix is passed over coarse mesh screens to increase the gravel content. The removed sand and silt is rejected overboard where it forms a sediment plume in the water column. The plumes are created over a six to eight hour period, depending on the size of the cargo. Monitoring has shown that the increased suspended sediment loads are transient, with concentrations of sediments returning to background levels within 6-7 tidal cycles (Marine Aggregate Licence Area 430: East of Southwold, Compass Hydrographic Surveys Ltd 2004). The suspended sediment concentrations created by activities at Alma are not as high as those created by the aggregate industry. Trenching activity will be of very short duration, to the order of two days, so any disturbance will be transitory, with concentrations returning to background levels within a few days to a week. Consequently, no residual impact on the water column is envisaged.

8.4 SEABED CONDITIONS

8.4.1 Baseline Data Sources

This section principally references the following primary and secondary data sources:

Gardline Environmental (2011). Alma Field Development Site Survey: Environmental Baseline & Habitat Assessment Survey. Ref 8602

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BGS (2004). Technical Report produced for Strategic Environmental Assessment – SEA2: North Sea Geology. TR_008.

DTI (2001a). Strategic Environmental Assessment of the Mature Areas of the Offshore North Sea - SEA 2. 8.4.2 Existing Baseline

8.4.2.1 Bathymetry and seabed topography

The site survey reports indicate that the seabed is relatively flat across the entire development area, gently increasing to the north-west with a negligible gradient (<1°). Water depths range locally from 73.8m (lowest astronomical tide, LAT) to 80.3m LAT (GGL 2011). The water depths at the individual drill centres and FPSO location are presented in Table 8-12 and Figures 8-3, 8-4 and 8-5. Table 8-12: Water depth Site Water depth (m) Northern drill centre 79.8 Southern drill centre 76.1 FPSO 74.1 Source: GGL (2011) 8.4.2.2 Seabed geology

This section provides an overview of the shallow geology of the Alma development area. The shallow geology encompasses the formation sequences, the presence of formation members and outlines sequence trends in the development area. This data was obtained in site specific surveys undertaken by Gardline (2011). Gardline surveys of the development area identified the shallow geology sequences. The top layer of the development area comprises a thin veneer of <1m Holocene sand throughout. This layer overlies the Whitethorn Member of the Forth Formation (very loose to very dense slightly silty sand) that was identified at the proposed southern drill centre and FPSO locations. This member appears to be absent at the northern drill centre site suggesting the member thins toward the north-west and west. The thickness of this member ranges up to 4m below the seabed at the FPSO location and 2.5m below the seabed at southern drill centre. The Fitzroy Member of the Forth Formation follows in the sedimentary sequence in the development area, ranging from up to 6m to 11m below the seabed. Following the Fisher Formation extends to depths of 41 to 42m and Ling Bank Formation to depths of 97 to 113m below the seabed (GGL 2011). A major north-west to south-west trending fault is located in the northern most part of the Alma development area, cutting through the north-eastern corner of Block 30/25 (BGS 2004). Site surveys around the proposed drill centres and FPSO locations identified no major or minor faults within shallow sedimentary sequences (GGL 2011).

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Figure 8-3: Bathymetry at northern drill centre

Source: GGL (2011)

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Figure 8-4: Bathymetry at southern drill centre

Source: GGL (2011)

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Figure 8-5: Bathymetry at FPSO location

Source: GGL (2011)

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8.4.2.3 Surface sediments

Sediment located at or within <1m of the surface of the seabed is considered as surface sediment. This section provides an overview of surface sediment typical to the wider region and details the site specific surface sediment characteristics obtained during Gardline surveys (2011) of the development area. Seabed sediment in the North Sea derives from the latter epoch of the Quaternary period, the Holocene (the past approx. 10,000 years through to the present). These sediments are distributed relative to historical and present hydrodynamic processes of the North Sea (BGS 2004). The surface sediment of the CNS is broadly characterised by mud and sands. Sediment type correlates with water depth, in deeper waters sediment is typically muddier with a less proportion of sand and in shallower depth sediment is sandy with a low mud content. Surface sediments of the CNS are typically >10,000 years old (Holocene epoch) (DTI 2001a). The Alma site survey (Gardline 2011) identified surface sediments consist of Holocene sands with a component of fine material (possibly silt) which appears to have in-filled troughs between sand ripples (Figure 8-6). The sediments are characterised as very loose to loose with a poor to moderate degree of sorting. Particle size analysis (PSA) from fifteen stations in the development area identified sediments typically range from fine to very fine (<63µm) in grain size, although there is occasional accumulation of coarse sediment. Sediment >2mm (gravels) were not identified in the area. Sediments grade finer with water depth, with coarser sediments located in shallower water depth (GGL 2011). There were also some potential outcroppings of the underlying boulder clay provisionally identified from the sidescan sonar (SSS) data. Figure 8-6: Example of seabed sediments from survey

Source: GEL 2011

There are north-east to south west orientated ripples throughout the development area. Areas of fine sediments in-fill the troughs with coarser sediments identified along the banks of the ripples. Areas of coarse sediment accumulations were identified at both the southern drill centre and the FPSO location. The accumulations of coarse sediment cover an area of approximately 0.5km wide (west to east) extending for the most part across the

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development area trending in a north-east to south westerly orientation. Two areas of accumulated coarse sediment are present. Sites of depressions in the seabed are located throughout the site. The depressions range from 10 to 20m up to 0.5km in length and are likely to be associated with the decommissioning of the Argyll/Ardmore field, i.e., spudcan depressions or depressions associated with the removal of infrastructure (Figure 8-7) (GGL 2011; BGS 2004).

8.4.2.4 Sediment contamination

Sediment contamination primarily is associated with oil and gas industry activity in the North Sea. Contamination results from drill cuttings and produced water. Produced water is the primary source of contamination now, with replacement methods in place reducing hydrocarbon contamination from drill cuttings. Sediment within an area of 500m around most offshore infrastructure is likely to be contaminated with hydrocarbons and a range of other compounds i.e., heavy metals (DTI 2001b). The organic content of sediment and particle size relates to the transportation and retention of contaminants. Sands and coarse sediment typically have a low organic content, whereas fine sediments typically exhibit higher organic content and are likely to be readily picked up and transported to lower energy environments (GGL 2011). Sediment samples were obtained during the Alma site surveys (Gardline 2011) at fifteen stations and were analysed for hydrocarbon and heavy metal contamination. Figure 8-3 provides the location of the sampling stations. Results indicated that there is hydrocarbon contamination across the site. Total hydrocarbon content (THC) in samples ranged from 5.58µg.g-1 to 90.75µg.g-1, although 95% of stations showed recordings of <40µg.g-1. Typically, THC for the North Sea is 9.51µg.g-1. Higher THC recordings were obtained in fine sediments in deeper waters. This is considered to be due to the low energy environment where contamination is not so widely distributed. Furthermore, the site is a historic field development area (Argyll/Ardmore developments) where drilling and production has been undertaken. Table 8-13 provides details of heavy metal concentrations recorded across the site from surveys undertaken by Gardline (GEL) in 2007, 2010 and 2011. This table demonstrates that the concentration of heavy metals in sediment recorded since 2007 has remained relatively consistent over this four year period. Given that this a developed site, the relative consistency of the heavy metal concentrations over this timeframe suggests that current speeds are insufficient to disturb/remobilise/flush out the historical contamination. Therefore, heavy metal contamination in the sediment is likely to remain at a constant level.

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Table 8-13: Heavy metals in sediment (µg.g-1) Sediment metal concentration Metal Gardline 2011 GEL 2010 GEL 2007 Al 13,687 14,300 As 5 4.2 4 Ba 571 235 257 Ba1 656 194 227 Cd 0 0.1 0 Cr 17 6.8 13 Cu 6 11 4 Fe 5,503 5,353 Hg2 0 0.03 0 Ni 4 3.4 4 Pb 18 10.9 13 Sn 1 1 V 26 8.6 15 Zn 20 16.8 20 Ba1. Concentrations determined following fusion with lithium metaborate and extraction with nitric acid Hg2. Concentrations determined following nitric acid digest preceded by digestion of organic matter with hydrogen peroxide Note: Blank cells represent no available data Source: GGL (2011)

8.4.2.5 Seabed features

A number of natural and man-made seabed features were identified in the Alma site surveys (Gardline 2011). As well as the natural ripples, and areas of coarser sediment discussed in Section 8.4.2.3, occasional boulders up to 1.2m in height from the seabed are distributed throughout the development area. A number of manmade depressions and many articles of debris e.g., bits of cable and pipe, related to disused/abandoned wells and fishing gear where identified. Depressions and scars are thought to be associated with the removal of infrastructure during the decommissioning of the Argyll/Ardmore field (GGL 2011). No evidence of reefs, eyed pockmarks or Annex I habitats (EC Habitats Directive 92/43/EEC) was apparent in the survey data (SSS or multi-beam echo sounder (MBES)).

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Figure 8-7: Sampling stations location overview

Source: GGL (2011)

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8.4.2.6 Sediment mobility

This section provides an overview of sediment mobility within the development area. Sediment mobility refers to the behaviours of the near and at-surface sediment that composes the seabed, as influenced by currents, waves and storm conditions. Water depths in the vicinity of the development range between 73.8m and 80.3m LAT. At these depths unconsolidated sediments are unlikely to be affected by wave stirring or storm induced currents (GGL 2011). Typical to the CNS, the Alma development area is characterised by very low sediment input and re-working of sediment by near bottom currents (BGS 2004).

8.4.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 8-14 have the potential to interact with the seabed. Table 8-14: Seabed conditions – potential impact identification Project Activity Aspect Potential Impact Construction Physical presence and Disaggregation of surface Anchoring movement of vessels sediments Discharge of cuttings Change in seabed topography Drilling of wells Discharge of chemicals (including WBM) Discharge of reservoir hydrocarbons Sediment contamination Discharge of chemicals (including WBM) Physical presence of subsea infrastructure Compaction and disaggregation and flowlines of surface sediments Change in surface sediments Installation of flowlines Trenching and backfill Change in seabed topography leading to changes in sediment transport pathways Concrete mattressing and rock placement Change in seabed topography Compaction and disaggregation Installation of FPSO Anchoring of surface sediments Production

Physical presence, operation Discharge of produced water Sediment contamination and maintenance of FPSO Discharge of chemicals Accidental Events Overboard loss of equipment Dropped objects Scour around objects or waste Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon Diesel, crude or chemical spill (including Sediment contamination release (1-10 tonnes) OBMs) Chemical / hydrocarbon release (>10 tonnes)

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In general, these aspects have only two potential impacts on seabed conditions; the potential to degrade and disturb the seabed sediments. The EIA concluded that activities have the potential to create both these impacts, generally on a site specific basis (i.e., effects restricted to the project area). Some of the accidental events assessed potentially have a much wider area of impact e.g., the local or wider region. The sensitivity of the receiving environment to the impacts ranges from low to medium and the majority of impacts are restricted to short-term effects. The assessment is provided in Sections D of Appendix A2 and A3 and Section B of Appendix A4.

8.4.4 Mitigation Measures

Footprints on the seabed will be minimised where possible. Concrete mattressing and rock material deposited for flowline protection will be placed on the seabed in such a manner that will minimise seabed disturbance. To reduce the impact of chemical operations on the seabed, chemicals that are environmentally benign will be preferentially selected. All discharges will be risk assessed and will be within permitted levels. OBM will be recycled throughout the drilling programme to minimise usage and will be shipped to shore on well completion. No OBM will be discharged to sea. Mitigation against accidental events includes conducting a debris clearance survey prior to each rig move, ensuring that any significant objects are removed. Regular inspections will be undertaken to establish that all equipment is in good working order and accidental spills will be kept to a minimum through training, good housekeeping and through storage/handling procedures. Sumps and drains should catch accidental spill releases, and management controls will be in place to eliminate bunkering spills (for example, only bunkering during good daylight conditions and in good weather). EnQuest will also ensure that a field specific OPEP is in place for the drilling and production phases.

8.4.5 Residual Impact Significance Assessment

8.4.5.1 Contamination of sediments

The EIA concluded that an unplanned hydrocarbon or chemical release of 1-10 tonnes had the potential to contaminate seabed sediments, with a residual impact of minor significance. A spill of <1 tonne at the surface is unlikely to contaminate seabed sediments. As discussed in Section 7.2.1 the possibility of a loss of containment has an estimated frequency of 32 incidents per annum and, it has been estimated that there is a 24% likelihood of a spill greater than 0.1 tonnes occurring during drilling at Alma. If this was to occur, it is possible that sediments may become contaminated with hydrocarbons, which are likely to persist for some time. SSS imagery of the project area shows rippled sand indicating sediment movement. It is possible that contaminated sediments could be dispersed, in effect reducing the localised concentration levels. Small spills are unlikely to be noticeable against current baseline levels below background levels.

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8.4.5.2 Physical disturbance causing a change to surface sediments

A number of project activities will impact the seabed either through compaction of surface layers or by physical disturbance, e.g., displacement and redistribution. A maximum of 0.04km2 of seabed will be disturbed by construction activities. Cuttings discharged directly on to the seabed will form a deposition pile around the wellhead. Section 6.1.3.4 estimated that the maximum total seabed footprint from all drill cuttings piles is 21,016m2, but more realistically is likely to be less than 2,992m2 as the wellheads are within 15m of each other (within their respective drill centres), and it is expected that cuttings piles will overlap, reducing the area of impact. Studies suggest that cuttings piles in the North Sea start to erode at current speeds greater than 0.35ms-1 (UKOOA 1999). As bottom currents in the development area are expected to be in the region of 0.42ms-1 it is thought that piles will erode and disperse, although cuttings piles in the CNS have been known to remain in place for 5-10 years (UKOOA 1999). However, there is no evidence on the survey data of previous drill cuttings piles suggesting that they will eventually be eroded completely. Activities which physically penetrate surface sediments, e.g., anchoring and trenching, will bring underlying sediments to the surface. As the anchor is withdrawn sediments from deeper lithologies (e.g., the underlying clay) will be brought to the surface. The seabed is likely to be visible disturbed after trenching and backfilling have taken place and anchors have been deployed. When retrieved the anchors are expected to leave a small area of disturbance and given the soil conditions at least half of this thickness will be in mobile/loose sediments rather than clay. The fluidisation technique used during jet-trenching is likely to remobilise the top 5cm of surface sediments into suspension in the water column. The jetting machine is designed to ensure that the majority of fluidised sediment stays in situ i.e. a trench is not formed. Suspended sediment should be minimised as there will be no mass expulsion of sediment from around the flowline (GdFB 2005). Inevitably, there will be some suspended sediment, but as the sediments in which the technique is typically used are sands, the sand is likely to settle out of suspension quickly. No significant mounds of sediment to either side of the route are likely to occur. The longevity of any anchor pull out depressions will be dependent on the sediments into which anchors have been secured. In the case of Alma these are predominantly sandy sediments overlaying sandy clay. The pull-out depressions are therefore expected to be negligible and will be degraded by the current regime in this area of the CNS. The presence of the concrete mattressing and rock protection on the seafloor may cause a slight variation in the local hydrodynamics. This could potentially cause slight scour and/or deposition in the immediate vicinity of the mattressing. This is of negligible significance in the wider scope of impacts. As the sediments within the development area are typical of the CNS region the sensitivity of the receptors has been assessed as low. Based on the EIA undertaken in Section D of Appendix A2, this indicates that anchoring and trenching of pipelines has the potential to have an impact of minor significance on seabed sediments.

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9 IMPACTS ON BIOLOGICAL ENVIRONMENT

This section describes the existing baseline biological environment, the impacts the Alma development will potentially have on this environment, how any impacts will be mitigated and qualifies the significance of any residual impacts. It follows the same structure as Section 8 and uses the methodology established in Section 4. The biological environment has been divided up into the following main areas:

Plankton (Section 9.1)

Benthic communities (Section 9.2)

Fish and shellfish (Section 9.3)

Seabirds (Section 9.4)

Marine mammals (Section 9.5)

Protected sites and species (Section 9.6)

9.1 PLANKTON

9.1.1 Baseline Data Sources

This section principally references the following data source:

Strategic Environmental Assessment of the Mature Areas of the North Sea (SEA2) (DTI 2001a) 9.1.2 Existing Baseline

Plankton can be divided into phytoplankton and zooplankton, representing plants and animals respectively and range from microscopic life to large species, such as jellyfish, which live freely in the water column and drift with the water currents. The plankton communities in the vicinity of the Alma development are expected to be typical of those of the CNS. Strong seasonal abundance patterns, governed by light and nutrient levels, are observed across the region. Favourable conditions lead to a spring bloom in phytoplankton (April-May) followed by a later bloom in the zooplankton, supported by the increased phytoplankton abundance. However, stratification of the water column limits plankton growth once available nutrients have been exhausted in the surface water. A second bloom occurs in the autumn when thermal stratification breaks down, allowing mixing of surface and nutrient rich deep waters. Superimposed on the annual cycle of plankton abundance in the North Sea are changes in community structure that occur over longer periods of time. For example, continuous plankton recorder (CPR) surveys have shown that phytoplankton biomass has increased over the last four decades over much of the North Sea. Hydroclimatic long period climate cycles such as the North Atlantic Oscillation have also been shown to play an important role in altering the plankton dynamics of the North Sea. Current research suggests that these have a greater impact on the planktonic communities of the North Sea than anthropogenic factors (DTI 2001a).

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9.1.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-1 have the potential to interact with plankton. Table 9-1: Plankton – potential impact identification Project Activity Aspect Potential Impact Construction Organic enrichment leading to Physical presence and movement Discharge of sewage, grey water, raised biological oxygen demand. of vessels food waste and drainage water May change balance of food chain. Discharge of chemicals (including Drilling of wells WBM) Discharge of reservoir hydrocarbons Potential toxic effects Discharge of chemicals (including Installation of flowlines WBM) Production Discharge of produced water Physical presence, operation and Potential toxic effects Discharge of chemicals maintenance of FPSO Organic enrichment leading to Discharge of sewage, grey water, raised biological oxygen demand. Physical presence and movement food waste and drainage water of export tanker and supply vessels May change balance of food chain. Accidental Events Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon release (1- Diesel, crude or chemical spill Potential toxic effects 10 tonnes) (including OBMs) Chemical / hydrocarbon release (>10 tonnes)

In general, the discharges of chemicals and hydrocarbons have the potential to degrade the plankton community, while discharges of sewage/food wastes etc could enrich communities locally. The EIA concluded that activities have the potential to create both these impacts, generally on a site specific basis (i.e., effects restricted to the project area). Some of the accidental events assessed potentially have a much wider area of impact e.g., the local or wider region. The sensitivity of the plankton community to these impacts ranges from low to medium depending on the impact and the majority of impacts are restricted to short-term effects. The assessment is provided in Sections E of Appendix A2 and A3 and Section C of Appendix A4.

9.1.4 Mitigation Measures

Measures outlined in Section 8.3.4 adopted to reduce and/or eliminate the toxic impacts of the development on water quality will also mitigate the potential impacts on plankton. These have not been repeated here but are listed in the previous sections and Sections E of Appendix A. In addition, all chemical discharges will be risk assessed and within the DECC permitted levels as per the relevant Offshore Chemicals (Amendment) Regulations (OCR) chemical permit i.e., PON15B, PON15C or PON15D.

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9.1.5 Residual Impact Significance Assessment

During construction and production, permitted chemicals will be discharged to sea either at the seabed or at sea level depending on their use. Some chemicals used often have the potential to cause toxic harm when discharged e.g., biocides or oxygen scavengers. In addition, if an accidental spill of greater than 10 tonnes of hydrocarbons or chemicals were to occur during the project life cycle it is expected that the plankton community would suffer from toxic effects. Studies indicate that zooplankton appear to be the most vulnerable group to toxic effects of chemical discharges, whereas the phytoplankton and fish larvae tend to be more robust to any direct effects (GESAMP 1993). Plankton organisms are generally short lived, however, and recovery following a pollution induced population reduction is usually rapid. The metocean conditions in the region will ensure chemical discharges are rapidly diluted and dispersed, minimising the extent of any effects. As such, the impacts of construction and production activities on plankton have been assessed as having no residual impacts after mitigation. The impact of an accidental spill of greater than 10 tonnes of hydrocarbons or chemicals has been assessed as having a minor impact after mitigation.

9.2 BENTHIC COMMUNITIES

9.2.1 Baseline Data Sources

This section principally references the following primary data source:

Gardline Environmental (2011). Alma Field Development Site Survey: Environmental Baseline & Habitat Assessment Survey. Ref 8602 9.2.2 Existing Baseline

During the 2011 Alma site survey fifteen stations were selected for investigation with the camera system and for sampling with a 0.1m2 day grab. Two stations were selected close to the proposed northern and southern drill centres (four stations in total), two stations close to the proposed FPSO riser base location and two stations along each of the proposed flowline routes between the drill centres and FPSO riser base. A further five stations were positioned in order to ground truth the sediment conditions in the area. Fauna observed during the environmental baseline survey (GGL 2011) included cnidarians (anemones), echinoderms (starfish and sea urchins), crustaceans (hermit crabs Pagurus bernhardus) and fish species including (but not limited to) flatfish. Visible fauna from Day grab samples included sea urchins, bivalve molluscs and annelid worms. The macrofauna was dominated by the polychaete worm Paramphinome jeffreysii, which was present in every sample and accounted for c.18% of all individuals identified. The bivalve Kurtiella bidentata was more abundant at some stations, however, generally it is has a patchy distribution and was absent at several stations sampled. Univariate statistics suggested that there was a lack of dominance structure in the area, and that the faunal community was generally rich and evenly distributed.

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A total of 12,187 individuals from 216 taxa were recorded in the retrieved samples. Of the individuals recorded, 2,367 (22% of the total) were juveniles from 26 taxa (12% of all taxa recorded). The dataset can be divided into five major taxonomic groups; Annelida (Polychaeta), Arthropda (Crustacea), Mollusca, Echinodermata and “Other” (made up of taxa from Cnidaria, Platyhelminthes, Memertea, Priapulida, Sipuncula, Phoronida, Hemichordata and Chordata) (GEL 2011). Table 9-2 shows the contributions of the gross taxonomic groups. Table 9-2: Contributions of the gross taxonomic groups Individuals Taxa Group Proportional Abundance Proportional Abundance Contribution (%) Contribution (%) Annelida 6251 51 101 47 (Polychaeta) Arthopoda 508 4 41 19 (Crustacea) Mollusca 2492 20 47 22 Echinodermata 2533 21 15 7 Others 403 3 12 6 Total 12187 100 216 100 Source: GEL 2011 Twenty taxa (9% of total recorded) were present at every station sampled, and nine (4%) were present in every sample taken. Of the nine, four were polychaetes, one was molluscan, three were echinoderms and one was “Other” (Nemertea). The most abundant species across the survey area was the polychaete P. jeffreysii which is tolerant of hydrocarbon contamination (Olsgard and Gray, 1995). The presence of this species cannot be assumed to be as a result of contamination across the survey area; however the elevated numbers seen at sample station ENV7 and ENV12 may be related to contamination at these stations. Amphiuridae sp. (juv) appeared to show decreased abundance at sample station ENV12, which suggests that the elevated hydrocarbon and metal concentrations at this station were sufficient to cause a change in abundance of some of the more sensitive species (GEL 2011). Table 9-3 shows the top 10 species seen during the survey. Table 9-3: Species ranking Rank Total rank Total Species/Taxon Fidelity Score Abundance score abundance 1 1 Paramphinome jeffreysii 141 0.94 2182 2 2 Amphiuridae sp. (juv) 136 1.01 1937 3 4 Galathowenia oculata 104 0.86 721 4 5 Pholoe assimilis 80 0.76 635 5 3 Kurtiella bidentata 70 0.77 1057 6 6 Vitreolina philippi 66 0.88 438 7 7 Nemertea sp. 33 0.55 264 8 10 Trichobranchus roseus 33 0.72 219 9 8 Amphiura filiformis 28 0.94 246 10 12 Eudorellopsis deformis 26 1.70 196 Source: GEL 2011 The survey found that overall community structure was comparable to that found in other surveys carried out in the area previously. The community was dominated by polychaetes and other typical CNS species were common GEL 2011).

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Variation in fauna present is likely to be a result of natural variation in water depth and sediment size coupled with the effects of the elevated hydrocarbon concentrations seen at some stations. However, the survey did not find consistently significantly differences between contaminated and uncontaminated samples. No habitats or species of conservation significance under the UK’s Offshore Marine Conservation (Natural Habitats, &c.) (Amendment) Regulations 2010 or EC Habitats Directive – Annex 1 species were observed. The photographs below (Figure 9-1) are representational of the seabed conditions observed during the baseline survey. Figure 9-1: Seabed photographs of the Alma development area

Source: GEL (2011)

9.2.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-4 have the potential to interact with the benthic community.

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Table 9-4: Benthic communities – potential impact identification Project Activity Aspect Potential Impact Construction Physical presence and Physical damage to individuals Anchoring movement of vessels Smothering Physical damage to individuals Discharge of cuttings Smothering Drilling of wells Discharge of chemicals (including WBM) Potential toxic effects Discharge of reservoir hydrocarbons Discharge of chemicals (including WBM) Potential toxic effects Physical presence of subsea infrastructure Habitat loss Installation of flowlines and flowlines Physical damage to individuals Trenching and backfill Smothering Concrete mattressing and rock placement Habitat creation Physical damage to individuals Installation of FPSO Anchoring Smothering Production Physical presence, operation Discharge of produced water Potential toxic effects and maintenance of FPSO Discharge of chemicals Accidental Events Overboard loss of equipment Dropped objects Physical damage to individuals or waste Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon Diesel, crude or chemical spill (including Smothering release (1-10 tonnes) OBMs) Potential toxic effects Chemical / hydrocarbon release (>10 tonnes)

In general the potential impacts identified above fall into two categories:

Impacts from chemical discharges e.g., lethal (direct) toxicity and sublethal (indirect) effects

Impacts resulting from physical disturbance e.g., smothering, damage to individuals or habitat loss The EIA concluded that there will be an interaction between the project activities and the benthic community but that any resulting impacts will be restricted to the project area. Changes to the baseline may only just be noticeable (i.e., sensitivity of low) but the duration of most impacts will be short- term (up to five years), the exception is the permanent siting of structures on the seabed which will have a long-term effect. The likelihood, spatial extent, frequency, duration, sensitivity, recoverability and significance of the impacts have been assessed in Sections F of Appendix A2 and A3 and Section D of Appendix A4.

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9.2.4 Mitigation Measures

Measures outlined in Sections 8.3.4 and 8.4.4 adopted to reduce and/or eliminate the toxic impacts of the development on water quality and the footprint of the development on the seabed will also mitigate the potential impacts on the benthic community. These are not repeated here but are listed in the previous sections and summarised in Table 12-2 and in Sections F of Appendix A2 and A3 and Section D of Appendix A4.

9.2.4.1 Physical disturbance

The main impact of construction activities on benthic communities results from physical disturbance to the habitat either as a result of direct removal of the habitat or smothering of individuals and/or the habitat. The Alma development will disturb approximately 0.04km2 of seabed. Disturbance will occur by a number of mechanisms:

Positioning of structures on the seabed, such as the manifold, drill rig anchors, well head xmas trees, concrete mattressing and rock protection

Flowline and umbilical installation e.g., trenching and backfill

Discharge of drill cuttings In all instances the direct result will be mortality of flora and fauna within the impact footprint. As demonstrated in Section 9.2, the species identified in the area are typical of the CNS, and no rare or protected species were identified in the environmental baseline surveys. The main species present in the project area are known to be generally tolerant of increased levels of suspended sediments and low levels of smothering but are generally intolerant of displacement (GEL 2011). This suggests that individuals on the periphery of the project footprint and to some extent within the direct footprint may show some tolerance to disturbance particularly if the disturbance is short-term in nature. However, species individuals will experience mortalities directly within the project footprint and in particular along the flowline corridors. Disturbance from the majority of project activities will cease within a few days, or at most within a few months, allowing for recovery and recolonisation of disturbed areas to commence almost immediately. The concept of recovery of biological resources is not easy to define as community composition can vary over time, even in areas that remain undisturbed. A key factor to be taken into consideration when determining whether a community is identical in species composition and population structure following cessation of impact, is whether the biodiversity would have remained stable over that period in the absence of disturbance. Furthermore, the rate of recovery depends on several factors, including:

Levels of natural disturbance

Coarseness of sediment

Water depth

Type of benthic community that is disturbed The types of benthic communities that typically colonise coarse sediments that are subject to natural disturbances by currents have much faster recovery rates than those species inhabiting consolidated sediments in low energy

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environments. Conversely, fine sediment communities, particularly those with slow growing long lived fauna, usually have slow recovery times. Mixing of surface sediments can result in a change in biological community type e.g., infill of depressions can result in detectable faunal difference on a local scale. However, the area impacted is minor when compared to the extent of the CNS and physical disturbance from other activities such as trawling. The majority of CNS seabed species have short life spans (< few years) and relatively high reproductive rates, indicating the potential for recovery within 5 years. Mobile organisms are less at risk as they are able to avoid the area of disturbance. The benthos in the project area is typical of the wider CNS and consequently species that inhabit the area tend to recover quickly after disturbance. The process of recovery is dependent on the species within the surrounding area, their respective life cycle characteristics and mobility. The primary mechanisms for recolonisation of an impacted area are:

Individuals migrate into displaced sediments from adjacent areas

Settling out of eggs and larval stages from the water column The proposed development is located within an area of previous drilling activity. The development area is sufficiently homogenous that any localised losses are unlikely to affect the integrity of the community as a whole. In general, recolonisation is expected to occur quickly with the initial appearance of opportunistic species such as polychaetes of the spionid family; followed by a progression over time to a more stable and diverse community, better representing the current conditions. At present there is very little available information on the rate of recovery of biological resources following the installation of pipelines/flowlines compared with the impacts from activities such as dredging and trawling. Physical disturbance will be the dominant mechanism of ecological disturbance from the jet trenching installation technique. The fluidisation of sediments may cause some fatalities of infauna, although this will be limited to the width of the fluidised sediment (typically only a little wider than the outer diameter of the pipeline). The deposition of suspended sediments may smother sessile species and filter feeders along the pipeline corridor, but the extent of this impact will be limited to a footprint no wider than 10m and the intensity of the impact will decrease with distance from the flowline. The recovery of benthic communities will partly depend on the community type present. As discussed above the benthic community associated with the Alma development area is typical of the wider CNS and is characteristic of a dynamic environment. To a certain extent, species are used to a degree of smothering caused by natural sediment movements and as such exhibit relatively quick recovery times. The surface sediments at the development consist of <1m thickness of very loose to loose silty shelly sands (with a varying degree of gravel and shells) over firm to very stiff sandy gravelly clay. Both the sand and clay will be suspended. The sand is likely to settle out of suspension soon after the disturbance close to the trench, potentially smothering sessile fauna in the immediate vicinity. The finer particle size of the clay (0.002mm) will remain in suspension, potentially for days, and will be transported by currents away from the flowline routes. These will gradually settle out, becoming deposited over a

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wider area. The layer of deposited clay material is likely to be very thin, possibly undetectable. Although the suspended clay is unlikely to smother sessile species the increase in turbidity may clog the filter feeding mechanisms of sessile species Furthermore, the altered sediment characteristics within the area affected by trenching may affect recolonisation of the impacted area. Although the sediments are likely to be uncontaminated they will contain a higher proportion of sandy gravelly clay from the Forth and Fisher Formations compared to the surrounding principally fine sand sediments. Recolonisation should be relatively quick, but it may be impeded by the change in sediment type. However, it will occur through the mechanisms discussed above. The placement of the manifold, concrete mattresses and rock protection material on the seabed will smother individuals within the immediate footprint of the structures. Sedentary species will be particularly vulnerable to burial as they are unable to avoid such disturbances. The area of hard substrate is expected to attract colonisation of certain species that require hard substrate for anchoring points, but it may take longer to establish a community due to the limited larval supplies in the predominantly sandy surrounding areas. However, the area affected is extremely small (0.04km2) in comparison to the considerable extent of sandy sediments in the wider region. As discussed in Section 6.1.3.4, the worst case total seabed footprint from all drill cuttings piles is 21,016m2. In reality this is more likely to be in the order of 2,992m2 or less, as the wellheads are within 15m of each other, and it is expected that the cuttings piles will overlap, reducing the area of impact. As bottom currents in the development area are expected to be in the region of 0.42ms-1 it is thought that piles will erode and disperse, although cuttings piles in the CNS have been known to remain in place for 5-10 years (UKOOA 1999). However, there is no evidence on the survey data of previous drill cuttings piles suggesting that they will eventually be eroded completely. Between wells there will be a two to three month period for benthic community recovery before cuttings are once again deposited. This cycle of deposition and recovery means that the community will stay in a perturbed state for at least a year and a half until all wells are completed. Thereafter, recovery within five years is anticipated, as discussed above. Eight anchors are deployed per drill centre within a radius of 1,000m (3,281ft) from the rig. The length of anchor chain depends on rig height, water depth and anchor point location, in this case around 1,000m. Future anchoring would be expected to use similar lay-out and anchor lengths. Anchor chain scars are produced as a result of the laying of the anchor chains on the seabed. Sidescan sonar images of the Alma Field area clearly show the impact of previous drilling operations. Impacts also occur when the anchors are pulled out. When anchors are lifted clear the anchor fluke levers sediment onto the seabed creating a scar in the seabed and in some cases a mound where clay clasts that have been removed by the anchors are subsequently dumped on the seabed. The size of the scar or disturbed mound is dependent on the seabed characteristics. Anchor scars are common where seabed sediments or shallow sub-surface sediments are composed of clay. Where clasts are stiff then this will also be conducive to coherent sections of clay being drawn out by anchors and then redeposited on the seabed. Sediments within the Alma Field

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comprise a thin layer of sand over sandy silty clay, which will be conducive to the creation of anchor scars and mounds. The size of the scars produced as the anchors are withdrawn will depend both on the size of the anchor and how they are withdrawn, as the method of withdrawal can reduce the scarring that occurs. On removal of anchor chains the soft seabed sediments would be expected to slump into any slight depressions that have been caused, even out the seabed topography. Anchor chain scars do not appear to cause an obstruction to bottom fishing as the survey has shown trawl scars crossing the anchor marks. Laying the anchor chains on the seabed is likely to cause some localised mortality of sessile benthic fauna. However, on removal of anchor chains lateral recruitment of megafauna is likely to occur with several days (FRS pers comm. 2008). The majority of CNS seabed species have short life spans and relatively high reproductive rates, indicating the potential for rapid recovery. The impact of anchors on biology will be similar to that of the chains with individuals within the impact zone of each anchor being crushed as the anchor is laid. Some smothering of individuals could also occur in the immediate vicinity as the anchors are withdrawn. From this assessment it is expected that anchoring has the potential to have an impact of minor significance on benthic communities. As a result of the placement of concrete mattress, flowlines and other subsea infrastructure, new habitat will be created for those species that require hard substrate for anchoring. This could lead to settlement of new species and the potential for a localised change in marine ecology (increased localised biodiversity). The EIA has concluded that there will be a residual impact on benthic communities from physical disturbance to the seabed, which may be noticeable when compared to the baseline. However, the disturbance will be localised to the immediate vicinity of the development. Therefore, the seabed activities that cause physical disturbance have been classed as having a minor residual impact.

9.3 FISH AND SHELLFISH

9.3.1 Baseline Data Sources

The following data sources have been used to inform this section:

Catch statistics, provided by the Marine Management Organisation from the iFish2 UK wide database (2004 to 2009)

Fisheries Sensitivity Maps for British Waters (Coull et al. 1998) 9.3.2 Existing Baseline

Approximately 230 species of fish inhabit the North Sea. Analysis of fisheries statistics from the Marine Management Organisation (MMO) provides a good indication of the type of species present in the development area. It should be noted that this does not provide a definitive guide to the fish and shellfish in the

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area, as this data is not collected to provide an account of the community structure. However, it serves as a useful indicator, as many of the species found in the North Sea are commercially exploitable. The North Sea has been divided into a number of rectangles by the International Council for the Exploration of the Seas (ICES), which are used to report fisheries statistics. The Alma development lies in ICES rectangle 41F2, and catch statistics for the period 2004 to 2009 were obtained for this area to inform the EIA. The most commonly caught species in ICES rectangle 41F2 are given in Table 9-5 below. Approximately 38 species are caught within this ICES rectangle, with landings between 2004 and 2009 being dominated by herring (Clupea harengus). Haddock (Melanogrammus aeglefinus), lemon sole (Microstomus kitt) and plaice (Pleuronectes platessa) were also caught in significant numbers. Table 9-5: Commonly caught species Demersal Pelagic Crustaceans Haddock Herring Norwegian lobster (Nephrops) Lemon Sole Mackerel Scallops Plaice Source: MMO (2011)

Fisheries sensitivity maps (Coull et al. 1998) have been used to identify the spawning (location where eggs are laid) and nursery grounds (location where juveniles are common) for commercial fish species in the vicinity of the development area. Information on spawning and nursery periods for each species is detailed in Table 9-6 below. Spawning in the region occurs mainly between April and September, with peaks in May, June and July. Juveniles from the species in Table 9-6 may be present in the region all year round. North Sea mackerel overwinter in the deep water to the east and north of the Shetland Islands, and on the edge of the Norwegian Deeps. In spring, they migrate south to spawn in the CNS between May and July. The pelagic eggs can be found in the CNS at depths to 60m below the surface (DTI 2001c). Table 9-6: Key sensitive periods for fish spawning and nursery Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mackerel S* S* S* S Lemon Sole S S S S S S Sprat S* S* S S Haddock N N N N N N Whiting N N N N N N N Key: S = Spawning, S* = Peak spawning, N = Nursery and blank = no sensitivity. Source: Coull et al. (1998) 9.3.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-7 have the potential to interact with fish and shellfish.

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Table 9-7: Fish and shellfish – potential impact identification Project Activity Aspect Potential Impact Construction Physical damage to individuals, collision Anchoring risk, smothering Organic enrichment leading to raised Discharge of sewage, grey water, food biological oxygen demand. May increase Physical presence and waste and drainage water plankton & fish populations changing movement of vessels balance of food chain Disturbance causing avoidance of Subsea noise spawning & nursery grounds Physical damage to individuals Loss of spawning & nursery ground Discharge of cuttings effecting stock viability Drilling of wells Physical damage to individuals Discharge of chemicals (including WBM) Discharge of reservoir hydrocarbons Potential toxic effects Discharge of chemicals (including WBM) Physical presence of subsea Habitat loss infrastructure and flowlines Installation of flowlines Physical damage to individuals Trenching and backfill Smothering Concrete mattressing and rock placement Habitat creation Physical damage to individuals, collision Installation of FPSO Anchoring risk, smothering Production Discharge of produced water Physical presence, Potential toxic effects operation and Discharge of chemicals maintenance of FPSO Organic enrichment leading to raised Discharge of sewage, grey water, food biological oxygen demand. May change Physical presence and waste and drainage water movement of export balance of food chain. tanker and supply Subsea noise Localised disturbance vessels Accidental Events Overboard loss of Dropped objects Physical damage to individuals equipment or waste Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon Diesel, crude or chemical spill (including Smothering release (1-10 tonnes) OBMs) Potential toxic effects Chemical / hydrocarbon release (>10 tonnes)

The majority of activities have been assessed as possibly having an impact on fish communities. The spatial extent of impacts range from local, for the majority of construction activities, to widespread for major accidental events. The sensitivity will be low with a short-term duration. The likelihood, spatial extent, duration, sensitivity, recoverability and significance of the impacts have been assessed in Sections G of Appendix A2 and A3 and Section E of A4.

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9.3.4 Mitigation Measures

Potential impacts that require mitigation basically fall into two categories: those that could have toxic effects and those that disturb the seabed causing loss of habitat and spawning/nursery grounds. Measures to mitigate deterioration in water quality and toxic effects of chemicals have previously been outlined in Section 8.3.4, whilst measures to minimise physical disturbance to the seabed are discussed in Section 8.4.4. They have not been repeated in full here but are summarised in Table 12-2 and are provided in Sections G of Appendix A. To reduce the impact of chemicals and waste on fish and shellfish, products that are environmentally benign will be preferentially selected for all project activities. All chemical discharges will undergo a risk assessment prior to discharge. Discharges of chemicals will not exceed values approved on the PON15 chemical permits. Chemical use and discharge will be minimised where operationally possible by measures such as recycling drilling muds. Waste storage procedures will be in line with the garbage management plans and current legislation governing discharges to sea from vessels (e.g. MARPOL). The footprint of construction activities will be minimised through careful project planning and design. For example, mattressing and rock protection will be the minimum required to ensure protection or stabilisation requirements are met. Management controls will be in place to reduce accidental events. The development and all activities will be covered by a field specific OPEP. Third party contractors will have their own procedures in place to mitigate accidents (including appropriate spill response equipment and trained deployment crews on-site) (see also 9.4.4 below). These will be fully considered and harmonised with EnQuest’s OPEP prior to operations commencing.

9.3.5 Residual Impact Significance Assessment

9.3.5.1 Habitat disturbance and noise

As construction activities will disturb 0.04km2 of the seabed, they have the potential to disturb the spawning grounds for demersal species such as haddock and whiting. The main disturbance (flowline installation) will take place during the first and second quarter 2013. Although disturbed, the composition of sediments is unlikely to significantly change and the habitat should still be suitable for spawning once construction has ceased. As the spawning area for the demersal species encompasses a large area of the North Sea, a small disruption at the development site is not anticipated to affect populations or stock viability. As a result of the placement of concrete mattress, rock protection, flowlines and other subsea infrastructure, new habitat will be created for those benthic species that require hard substrate for anchoring. This could lead to settlement of new species and the potential for a localised change in marine ecology (increased localised biodiversity). This could in turn lead to more food sources for fish and shellfish species. The EIA concluded that there will be no residual impacts from habitat disturbance.

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As the majority of the noise generated by offshore oil installations is low frequency (<1kHz), any impact is likely to be minimal. Noise from piling has the potential to have a greater impact; however, the duration of noise generation from piling will be significantly less than that of general construction (including drilling) and the noise generated by vessels present during the construction period. Although noise from piling has the potential to adversely affect spawning and nursery grounds, piling activities will be limited in duration (approximately two days) and should not have a significant impact on fish and shellfish. The EIA concluded that the residual impact from noise during construction is minor.

9.3.5.2 Toxic effects

Two accidental events were assessed as having the potential to have a residual impact of minor significance on fish communities:

Loss of containment in production flowline

Release of hydrocarbons (>10 tonnes) The likelihood of either event occurring has been assessed in Sections 7.2.1 and 7.2.2, and is minimised through legislation governing the industry and mitigation measures consistent with best industry practice. In summary, it has been estimated that the probability of a spill >1 tonne occurring per annum is 24% from the drilling rig (i.e., during field construction phase). In contrast, the likelihood of such an event occurring during the production phase is very low (<1% over field life) especially given the current legal requirements and management procedures in place to mitigate impacts with significant consequences. In fish life cycles the egg and juvenile stages are the most vulnerable to toxicity in the water column, as adult fish are highly mobile and generally able to avoid localised polluted areas. Localised fatalities would occur as the pipeline breaches, but fish are likely to avoid the area if the situation persists, and any effects are unlikely to be felt on a population level. As discussed in Section 9.3.2 the Alma development area lies within the spawning areas for mackerel, lemon sole and sprat and within the nursery areas for haddock and whiting (Coull et al. 1998). However, the spawning/nursery grounds span large areas of the North Sea which will mean that long-term changes to populations are minor. In general, lighter refined petroleum products such as diesel and gasoline are more likely to mix in the water column and are therefore more toxic to marine life. However, they tend to evaporate quickly (as demonstrated in the oil spill modelling) and do not persist long in the environment. Although heavier residual oils tend to have specific gravities greater than sea water, causing them to sink once spilled, the reservoir oil at Alma is light crude which is unlikely to sink. A major hydrocarbon spill has therefore been assessed as having the potential for an impact of minor significance on fish and shellfish.

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9.4 SEABIRDS

9.4.1 Baseline Data Sources

The principal data sources used to inform this section were:

Atlas of seabird distribution in the north-west European waters (Stone et al. 1995)

Seabird vulnerability in UK waters: block specific vulnerability (JNCC 1999)

Strategic Environmental Assessment of the Mature Areas of the North Sea (SEA2) (DTI 2001a) 9.4.2 Existing Baseline

The CNS is an important area for guillemots (Uria aalge), fulmars (Fulmarus glacialis), gannets (Sula bassana), kittiwakes (Rissa tridactyla), herring gulls (Larus argentatus), great black-backed gulls (Larus marinus), and little auks (Alle alle). In July, large concentrations of guillemots occur in the CNS, with a gradual movement towards eastern Scotland and north-east England through August and September, and onwards dispersal to a more widespread distribution in the Southern North Sea in winter (DTI 2001a). The density and distribution of seabirds varies throughout the year. The breeding season extends from May to June with birds congregating at coastal colonies from March onwards. During this time seabirds remain close to their colonies, and numbers of birds at sea decrease. By late summer many species, such as guillemots and razorbills, leave their colonies and undergo a post-breed moult during which they are flightless. Significant concentrations of moulting adults and associated fledgling juveniles congregate on the water. Following the autumnal moult seabirds begin to disperse to their wintering grounds (Stone et al. 1995). Skov et al. (1995) detailed an Important Bird Areas (IBA) programme which identifies a network of sites, at a biographic scale, which are critical for the long term viability of bird populations. Although the areas are not afforded any statutory protection, they do serve as a useful indication of which areas of UK waters are of particular importance to seabirds. The Alma development is located approximately 46km north east of IBA 9 (Northeast Bank) (Figure 9-2). The IBA is an important breeding and feeding area for many vulnerable bird species including fulmars, gannets and the great skua (Catharacta skua) As specified by the JNCC (1999), seabird vulnerability refers to susceptibility to surface pollutants, specifically hydrocarbons, following breeding and during moulting at sea. Seabirds are also vulnerable to oil spills during the winter months when they congregate in large flocks on the water. The details of seabird vulnerability in Blocks 30/24 and 30/25, within which the Alma development lies, and the surrounding blocks are given in Table 9-8. The development blocks are shown in bold. Information on seabird vulnerability is also shown in Figure 9-2.

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Legend Alma Field Development Environmental Statement

Median Line Figure 9-2: Environmental overview Land UKCS Block Date Friday, July 8, 2011 17:14:41 Projection ED 1950 UTM Zone 31N XW Uisge Gorm FPSO Spheroid International 1924 !. Northern Drill Centre Datum D European 1950 !. Southern Drill Centre Data Source EnQuest, JNCC, UKDeal, Skov et al 1998 Production Flowline WI Flowline File Reference J:\P1459\Mxd\Environmental Statement\.mxd Figure 9-2 Environmental Overview

! ! ! Dogger Bank pSAC

! ! Produced By Louise Mann ! ! Net Gain draft MCZ ! Checked Reviewed By Anna Farley Northeast Bank IBA Annual Seabird Vulnerability 1 - Very High 2 - High 3 - Moderate

Table 9-8: Seabird vulnerability Block Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 30/18 2 4 4 4 4 4 4 4 4 3 3 3 30/19 3 4 4 4 4 4 4 4 4 3 4 3 30/20 2 4 4 4 4 4 4 4 4 2 3 3 30/23 2 2 3 4 4 4 4 4 4 2 3 3 30/24 2 4 3 4 4 4 4 4 4 2 3 3 30/25 2 4 3 4 4 4 4 4 4 2 3 3 30/28 2 2 3 4 4 4 4 4 4 2 3 4 30/29 2 4 3 4 4 4 4 4 4 2 3 4 30/30 2 4 3 4 4 4 4 4 4 2 3 4 31/21 2 4 4 4 4 4 4 4 2 3 31/26 2 4 4 4 4 4 4 4 2 4

Key 1 = Very High 2 = High 3 = Moderate 4 = Low Blank = No data Source: JNCC (1999)

The data in Table 9-8 suggests seabird vulnerability is generally low for most of the year, with a significant increase in vulnerability in January and October. This increase in vulnerability is probably the result of the arrival of over- wintering birds.

9.4.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-9 have the potential to interact with seabirds. Table 9-9: Seabirds – potential impact identification Project Activity Aspect Potential Impact Construction Physical presence and Localised disturbance of Increased vessel activity in region movement of vessels seabirds from the sea surface Discharge of chemicals (including WBM) Drilling of wells Discharge of reservoir hydrocarbons Potential toxic effect Installation of flowlines Discharge of chemicals (including WBM) Production Physical presence, operation and Discharge of produced water Potential toxic effect maintenance of FPSO Discharge of chemicals Physical presence and Localised disturbance of movement of export tanker and Subsea noise seabirds supply vessels Accidental Events Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon release Diesel, crude or chemical spill (including Smothering (1-10 tonnes) OBMs) Potential toxic effects Chemical / hydrocarbon release (> 10 tonnes)

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In general, these aspects have the potential to adversely affect seabirds. The EIA concluded that activities have the potential to create both these impacts, generally on a site specific basis (i.e., effects restricted to the project area). Some of the accidental events assessed potentially have a much wider area of impact e.g., the local or wider region. The sensitivity of the impacts varies from low to medium depending on the activity but all impacts are restricted to short- term effects. The assessment is provided in Sections H of Appendix A2 and A3 and Section F of Appendix A4.

9.4.4 Mitigation Measures

General mitigation measures to minimise the toxic potential of chemicals and thus reduce exposure concentrations for seabirds will be in place, as discussed in detail in Section 8.3.4 and Appendix A. Accidental spills of hydrocarbons present the largest potential impact on seabirds and as such the mitigation measures to prevent crude oil and diesel spills are discussed in more detail in this section. EnQuest considers three levels of mitigation for hydrocarbon spills:

1) Prevention In light of the significant consequences of a major accidental discharge, all operational personnel, whether in the direct employ of EnQuest or contractors will be made aware of existing environmental protection procedures and the crucial importance of maintaining the integrity of the containment policy. The risk of a spill is mitigated on a daily basis by EnQuest employees and contractors following good practice codes, collision avoidance and fuel handling and transfer procedures. Every effort will be made to prevent such spills. It is noted that most spills occur during offshore fuel transfer operations (bunkering) and as such EnQuest are committed to the following measures:

Fuel will be transferred between the vessels via hoses that will be equipped with a one way valve.

Bunkering operations will be conducted during day light hours and in good weather, where possible. If during winter this is not possible, transfers will be assessed to identify potential risks and any risks mitigated to acceptable levels.

A continuous watch will be maintained during offloading

All bunkering operations will be conducted in strict compliance to contractor’s procedures. These procedures will be referenced in a combined EnQuest HSE Management System Bridging Document, which will be circulated to all appropriate personnel.

The management of bunkering operations will be discussed with the contractor’s team prior to commencement of operations. 2) Control During the construction phase, the contractors owning each of the various construction vessels deployed will retain individual responsibility for spills and maintain approved shipboard oil pollution emergency plans (SOPEP). A Alma development OPEP will be developed in line with the Merchant Shipping (Oil Pollution Preparedness and Response Convention) Regulations

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1998, the UK Energy Research Centre and the latest DECC guidance on OPEP requirements following the Gulf of Mexico spill. The response to hydrocarbon release during the drilling and production phases will be outlined in an OPEP and referenced in a combined EnQuest HSE Management System Bridging Document, which will be circulated to all appropriate personnel. The OPEP will provide detailed hydrocarbon release and spill scenarios to enable the determination of appropriate offshore actions, and reporting and training requirements for mitigating accidental spillage throughout all phases of the development. The OPEPs will provide further detail on this assessment and, in addition, will include:

Definition of the response actions, including the roles and responsibilities of offshore and onshore personnel.

Reporting requirements of incidents, both internally amongst the offshore team (including contractors), and externally to statutory bodies such as the DECC, Her Majesty’s Coast Guard (HMCG) and the JNCC.

Model-based methodologies for determining the volume and potential movement of slick based on the modelling. The scenarios identified for modelling as discussed below. Three possible incidents have been identified within the project scope as potential sources for a major spill of hydrocarbons (>10 tonnes): a) Loss of diesel inventory from the FPSO and tanker through collision – 2,400m3 (2,016 tonnes) from the FPSO and 3,430m3 (2,881 tonnes) from the export tanker b) Loss of crude oil inventory from the FPSO and tanker through collision – A maximum of 100,000m3 (87,000 tonnes) as neither vessel will be full at the same time c) Loss of diesel inventory from the drilling rig – 1,665m3 (1,399 tonnes) Stochastic and trajectory modelling to determine the potential extents of the spills was undertaken for scenarios 1 and 2. Modelling was not undertaken for scenario 3 as it was a smaller volume than scenario 1 and therefore it can be inferred that the extent of the spill would be less. For scenario 2, as neither vessel would be full at the same time, the larger inventory (export tanker) has been modelled. The modelling results are presented in Section 7.3 and Appendix B. The most recent UK guidance on oil pollution emergency response requires Operators to model a loss of well control (blow out), as this although an extremely rare occurrence in the UK is considered to be the worst case volume of crude oil that could be spilt from a development. After consultation with the DECC Offshore Inspectorate this modelling has not been run for the Alma development due to the low reservoir pressure. From the very start of field life, reservoir pressure is such that ESPs will be required to pump crude oil out of the reservoir. In the event that well control is lost the wells will effectively self- kill. Instead, the worst case crude spill would be if the FPSO and export tanker collided with each other. As neither vessel will be full at the same time, only the larger crude oil inventory has been modelled (export tanker). For the diesel, the combined inventories of both the FPSO and export tanker have been modelled.

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EnQuest is also a member of OSPRAG which will provide support in the event of a major spill occurring.

3) Remediation Any spills (crude oil, diesel or chemical), including sheens, will be reported to the statutory authorities using the PON1 system. For larger spills, a comprehensive range of back-up resources is available to EnQuest through oil spill providers. This includes trained staff, aerial surveillance and dispersant spraying capabilities. The EnQuest strategy for diesel spills in this region is to allow natural dispersion and to monitor the progress of this dispersion. In the unlikely event that a large crude spill occurred advice would be sought from the DECC, the Defra and the JNCC as to whether dispersant spraying would be appropriate and would be approved.

9.4.5 Residual Impact Significance Assessment

Mitigation measures taken during construction and production phases have been assessed to reduce the impact on seabirds in the area. As such, none of these activities have been taken forward for residual impact significance assessment (see Sections H of Appendix A2 and A3).

9.4.5.1 Accidental events: spill of hydrocarbon >10 tonnes

There is the potential that seabirds could be significantly affected if a large crude oil spill was to occur. As discussed in Section 7.2 the probability of a spill >0.1 tonnes occurring during drilling has been estimated as 24%. Available data is not sufficient to calculate the probability of a spill >10 tonnes occurring but it is likely to be rare. The frequency of the flowline failing in open sea is 0.00125 times per year. A diesel spill will rapidly evaporate on release and will naturally disperse in the high energy offshore environment. Modelling, presented in Section 7.3.2, indicates that a diesel spill of 5,830m3 i.e., from a combined loss of inventory from the FPSO and export tanker, will naturally disperse and evaporate within 10 hours. As such, it is not considered that diesel will pose a significant threat to seabirds. A worst case crude oil spill scenario has been modelled to inform the EIA; a full loss of containment if the FPSO and export tanker were to collide. The modelling results are presented in Section 7.3.1. In this scenario, modelling shows that in the event of a worst case (the larger inventory from the export tanker) crude oil loss of 100,000m3 (87,000 tonnes) then depending on the prevailing wind conditions at the time there is a 1% chance of oil beaching along a coastline of one of the countries bordering the North Sea. Trajectory modelling indicates that:

3 With a prevailing wind towards the UK coastline: 86,393m of crude oil could beach on the North Yorkshire coastline

With a prevailing wind towards the nearest international boundary (UK/Norway): 161,742m3 of emulsified crude oil could beach on the Danish coastline Modelling results are presented in Appendix B.

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A spill of the magnitude modelled above is likely to significantly impact populations of seabirds. Seabirds that spend majority of the time on sea surface are most vulnerable as birds can be smothered by oil or their feathers can become contaminated with hydrocarbons, which in turn may be ingested. Seabird vulnerability to hydrocarbon pollution is highest in January and October. As the drilling rig will be on-site from December 2011 until January 2013, there will be overlap with the sensitive periods for seabirds. In addition, the FPSO will offload crude oil every two weeks throughout the year and therefore at some point each year operations will overlap with the sensitive periods identified. In the event of a spill occurring, the required intervention response will be implemented to minimise the risk of smothering and species injury. It is highly unlikely that a spill of the magnitude discussed above will occur. Mitigation measures outlined in the OPEP and management controls to eliminate spills should prevent any sizeable spills. Given the likelihood of an impact occurring is unlikely the EIA concluded that residual significance of the impact is moderate.

9.5 MARINE MAMMALS

9.5.1 Baseline Data Sources

This section draws upon information given in the following data sources:

Atlas of Cetacean distribution in northwest European waters (Reid et al. 2003)

Background Information on Marine Mammals Relevant to SEA2 (DTI 2001d).

Background information on marine mammals relevant to SEA 2 and 3 (DTI 2002)

The effects of seismic activity on marine mammals in UK waters (Stone 2003)

The protection of marine European Protected Species from injury and disturbance guidelines (JNCC 2010)

UK Offshore Energy Strategic Environmental Assessment. Environmental Report (DECC 2009b) 9.5.2 Existing Baseline

Distribution of species in UK waters is dependent on their lifestyle characteristics. For example some species are more frequently found on the continental shelf or in areas of deep water (e.g., white-beaked dolphin), whilst others are more commonly found in inshore waters (e.g., bottlenose dolphin). There are eight marine mammal species that occur regularly over large parts of the North Sea (DTI 2001d):

Harbour porpoise (Phocoena phocoena)

Bottlenose dolphin (Tursiops truncatus)

White-beaked dolphin (Lagenorhynchus albirostris)

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Atlantic white-sided dolphin (Lagenorhynchus acutus)

Killer whale (Orcinus orca)

Minke whale (Balaenoptera acutorostrata)

Harbour seal (Phoca vitulina)

Grey seal (Halichoerus grypus) Cetaceans The CNS region is important for the three most abundant cetacean species in the North Sea: minke whale, harbour porpoise, and white-beaked dolphin. Current evidence suggests that the CNS is particularly important for the harbour porpoise. Densities are greatest in summer, north of 56ºN and between 1ºE and 3°E (DTI 2001d). This area includes the prospective field development location. Table 9-10 below details the cetacean sightings data for the Alma field. This data suggests that nine species are present within and adjacent to the field and that most sightings occur during the summer months (Reid et al. 2003). Table 9-10: Cetacean observations in the area of interest Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Minke Whale 2 2 2 2 3 3 3 3 2 2 3 3 Killer Whale 1 1 1 1 1 Harbour Porpoise 1 1 1 1 2 3 4 2 2 2 1 1 Risso's Dolphin 1 1 2 1 1 1 White Beaked Dolphin 1 2 1 1 4 2 4 3 3 3 3 1 White Sided Dolphin 1 1 1 3 2 4 Bottlenose Dolphin 1 1 1 1 1 1 3 2 1 1 1 1 Common Dolphin 2 2 Key: Blank cell: Little or no observational effort and/or unlikely to be present in CNS, 1: Recorded in CNS, 2: Recorded in blocks adjacent to area, 3: Recorded in development area, 4: Frequent in development area. Source: Reid et al. (2003)

Harbour porpoise, white-beaked dolphins, minke whales and killer whales are typically seen in pods of less than ten animals. Activities that would disturb a significant group of these animals would have to be one that lasted for a considerably long period of time (JNCC 2010). Atlantic white-sided dolphin, Risso’s dolphin and pilot whales tend to form pods of greater than twenty animals. Table 9-11 presents abundance and density estimates for the five species identified as occurring in the development area (taken from Table 8-10). The conservation status of the species is also included. It is an offence under the Conservation (Natural Habitats etc.) Regulations 1994 (as amended) (HR) and the Offshore Marine Conservation (Natural Habitats, etc.) Regulations 2007 (as amended in 2010) (OMR) to deliberately capture, injure, kill or disturb any wild animal of an EPS. All cetacean species are designated as European Protected Species (EPS). Disturbance of animals includes, in particular, any disturbance which is likely to: a) Impair their ability - (i) to survive, to breed or reproduce, or to rear or nurture their young; or

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(ii) in the case of animals of a hibernating or migratory species, to hibernate or migrate; or b) Affect significantly the local distribution or abundance of the species to which they belong. Table 9-11: Cetacean population estimates and conservation status Species Natural UK SNS & southern CNS Species Significant Range Population Population Density Favourable Group (km2) Estimate Estimate1 (animals/km2) Conservation (animals) Status Harbour porpoise Unknown 328,200 129,000 0.46 Favourable 4,600 (39%) White-beaked Unknown 22,400 493 (2%) 0.0031 Favourable 450 dolphin Minke whale 759,000 13,800 4,700 (34%) 0.017 Favourable 330 White-sided dolphin Unknown 27,300 405 (1.5%) 0.0026 Unknown 100 Bottlenose dolphin 759,000 8,000 395 (5%) 0.0032 Favourable 160 Note 1: Percentage of UK population presented in brackets. Source: JNCC (2009), SCANS-II (2008), DECC (2009b)

Pinnipeds The two most common species of pinniped (seal) in the North Sea are the harbour (or common) (Phoca vitulina) and grey seals (Halichoerus grypus). The harbour (common) seal is one of the most widespread pinniped species and has a practically circumpolar distribution in the Northern Hemisphere. The distribution of harbour seals at sea is limited by the need to return to land periodically. Until recently, data showed they were unlikely to be found more than 60km from the coast, although recent telemetry studies show a wider distribution across the North Sea (DTI 2002). Grey seals have a wide distribution across the north-western Atlantic, Baltic and north east Atlantic seas. Populations in the North Sea account for approximately 50% (~70,000 individuals) of the northeast Atlantic population. Grey seals are mainly distributed around and between haul-out sites and foraging areas and are more commonly seen in the CNS and NNS than in the SNS (DTI 2002). It is possible that both species may be observed in the development area although it is unlikely given the distance offshore.

9.5.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-12 have the potential to interact with marine mammals.

In general, these aspects have the potential to adversely affect marine mammals, through risk of collision, disturbance and through the deterioration of individuals. The EIA concluded that activities have the potential to create both these impacts, generally on a site specific basis (i.e., effects restricted to the project area). Some of the accidental events assessed potentially have a much wider area of impact e.g., the local or wider region. The sensitivity of marine

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mammals to the impacts varies from low to medium depending on the activity but all impacts are restricted to short-term effects. The assessment is provided in Section I of Appendix A2 and A3 and Section G of Appendix A4. Table 9-12: Marine mammals – potential impact identification Project Activity Aspect Potential Impact Construction Can cause physical injury or Subsea noise disturbance Physical presence and movement Anchoring Collision risk of vessels Feeding impairment due to Discharge of sewage, grey water, food organic enrichment effecting waste and drainage water balance of food chain Discharge of chemicals (including WBM) Potential toxic effect Discharge of reservoir hydrocarbons Drilling of wells Localised disturbance of Subsea noise marine mammals Installation of flowlines Discharge of chemicals (including WBM) Potential toxic effect Can cause physical injury or Installation of FPSO Subsea noise disturbance Production Presence of FPSO and anchors Collision risk Physical presence, operation and Discharge of produced water maintenance of FPSO Potential toxic effect Discharge of chemicals Physical presence and movement Localised disturbance of of export tanker and supply Subsea noise marine mammals vessels Accidental Events Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon release Diesel, crude or chemical spill (including Potential toxic effect (1-10 tonnes) OBMs) Chemical / hydrocarbon release (>10 tonnes)

9.5.4 Mitigation Measures

General mitigation measures to minimise the toxic potential of chemicals and thus reduce exposure concentrations for marine mammals will be in place, as summarised in Table 12-2 and detailed in Sections I of Appendix A2 and A3 and Section G of Appendix A4. Releases of hydrocarbons will be mitigated through a three stage process: prevention, control and remediation. This is discussed in detail in Section 9.4.4 and has not been repeated here. To mitigate potential near field impacts on marine mammals from subsea noise during piling, the JNCC ‘Statutory nature conservation agency protocol for minimising the risk of injury to marine mammals from piling noise’ (JNCC 2010) guidance on minimising disturbance will be followed. EnQuest are committed to the following measures:

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Piling vessel will have a marine mammal observer (MMO) onboard.

Piling will not commence during periods of darkness or poor visibility (such as fog).

A pre-piling search will be conducted by the MMO. Piling will not commence if marine mammals are detected within 500m of the activity or until 20 minutes after the last visual detection.

Slow start-up i.e., gradual ramping up of piling power, will be used for piling to ensure that any mammals outside the observation zone will have sufficient time to leave the area. The soft-start duration will be not less than 20 minutes.

If a marine mammal comes within 500m of the piling during the soft-start, then if possible the piling will cease or at the very least the power will not be ramped up further until the marine mammal has left the zone and there has been no further detection for at least 20 minutes.

If a marine mammal comes within 500m of the piling when piling at full power there is no requirement to reduce the power, it is deemed to have entered voluntarily.

If there is a break in the piling operations for a period greater than 10 minutes then the pre-piling search and soft-start procedure should be repeated.

If required, EnQuest will apply for an EPS/wildlife licence. Activities will be undertaken in accordance with any conditions attached to the EPS licence. EnQuest will comply with reporting requirements outlined in the protocol.

9.5.5 Residual Impact Significance Assessment

9.5.5.1 Subsea noise

Cetaceans use sound to communicate, socially interact, and in some cases navigate using echolocation. There are two principal effects to exposure to noise; physical injury or physiological effects and effects associated with behavioural disturbances. Anthropogenic sources of noise therefore have the potential to interfere with their natural functions, and if the cetacean is within close proximity to loud noises, this can have the potential to cause physical injury (Stone 2003). During construction and production, a range of activities will generate low levels of underwater noise consistent with a development of this size. These include: flowline laying and trenching, subsea installation, subsea monitoring and repair, vessel manoeuvring and drilling (see Section 6.1.2.3). The majority of the noise sources are typical of construction activities associated with a small - to medium-sized development and are generally below 180dB. However, it is possible that background subsea noise generated by construction vessels and drilling may be audible to marine mammals within 1km of the source of sound. The major source of underwater noise during construction will be from the piling of the FPSO anchors and riser tethers. Impact piling involves the instantaneous application of pressure to a solid structure and is characterised by short, impulsive noise events as the pile drive strikes the pile. Impact durations are typically between 50 and 100ms and intervals between impulses

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range from one to two seconds. The source level noise from this type of piling is related to the diameter of the pile being driven. Subsea noise can affect marine mammals in three ways: blast impact, lung/organ resonance and hearing impairment. Of these three mechanisms, the first two have been discounted from the following assessment on the basis that mitigation measures will be in place to ensure that the piling activities will not commence with marine mammals in the immediate vicinity of the vessel. The potential for harm from noise is dependent on the animal’s hearing ability across the range of source frequencies. A noise exposure assessment has been carried out to ascertain whether injury and/or disturbance thresholds are likely to be exceeded. The JNCC (2009) suggested risk assessment approach that has been followed is provided as Figures D-1 and D-2 in Appendix D. Below is a summary of the risk assessment and the main conclusions. Noise levels Piling noise is dependent on the pile diameter, depth and soil stiffness. At the time of writing, piles have yet to be specified and a conservative assumption of 24” diameter by 20m long has been applied. This would lead to an estimated noise level of 189 dB SEL re 1µPa2-s at one metre from the source (assumed to be close to the seabed). Piling will be limited in duration to approximately two hours per pile, which includes handling of the pile and change over to the next pile. 15 piles will be driven during one 48 hour period. The piles will be installed between January and April 2013. Could sound experienced exceed injury and disturbance thresholds? On the basis of observed cetacean physiological and behavioural responses to anthropogenic sound Southall et al. (2007) proposed precautionary noise exposure criteria for injury and behavioural responses. To prevent injury in cetaceans, or a permanent shift in hearing thresholds the exposure threshold should correspond to a received sound exposure level (SEL) of 198dB re 1µPa2-s or a received sound pressure level (SPL) of 230dB re 1 µPa whichever is exceeded first. For pinnipeds the threshold for physical injury is 186dB re 1µPa2-s. The threshold for strong avoidance behaviour was established as a SEL of 160dB re 1µPa2-s for low frequency cetaceans (e.g., mysticetes) and 180dB re 1µPa2-s for mid/upper frequency cetaceans (e.g., odontocetes). Sound is attenuated as it propagates through water and can be expressed as: SPL = SL – N log R In this equation SPL = sound pressure level, R is the distance from the source level (SL) and N is the attenuation constant associated with the method of spreading. For this assessment spherical spreading (N=20) is assumed for the first 80m (i.e., until the sound wave reaches the seabed) and cylindrical spreading (N=10) thereafter. Assuming the source to be near the seabed, for a receptor 10m below the surface, the noise would have reduced to approximately 153dB SEL vertically

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above the source. This is 7dB below the lowest of the above thresholds for strong avoidance behaviour (160dB SEL). Table 9-13 shows how the SEL attenuates with distance from the piling. They also demonstrate that the SEL never exceeds the threshold for physical injury for cetaceans or pinnipeds, even within 1m of the sound source. Table 9-13: Sound exposure levels at distance Distance (m) SEL (dB) 1 153 25 153 50 151 100 149 200 147 300 145 400 143 500 143

JNCC (2009) state that for most cetacean populations in UK waters, disturbance, in terms of the HR and OMR, is unlikely to result from single, short-term operations e.g., the driving of a dozen small diameter piles. Such activities would most likely result in temporary disturbance, which on its own would not impair the ability of an individual to survive, reproduce etc, nor result in significant effects on the local abundance or distribution. Marine mammals are observed to show direct behavioural responses to certain types of severe subsea noise disturbance such as pile driving, including moving away from an area for a period of time, diving behaviour changes (e.g., reduced surfacing times), vocalisation changes and separation of mothers and calves (JNCC 2010). However, several authors have pointed out that the level of sound received does not seem to be the sole important aspect in determining the response and its significance (JNCC 2010). As discussed above, Southall et al. (2007) also proposed thresholds at which cetaceans may demonstrate avoidance behaviour. The calculations shown above also indicate that noise levels never exceed the threshold for physical injury for cetaceans or pinnipeds within 500m of the piling activity (maximum SEL of 153dB at 1m). In conclusion, following the risk injury and non-trivial disturbance assessment flow charts (provided in Appendix D) as the sound experienced at 500m does not exceed the injury or deliberate disturbance thresholds, provided the mitigation measures are followed, there is a negligible risk of an offence under the Conservation (Natural Habitats &c) Regulations 1994 (as amended) and the Offshore Marine Conservation (Natural Habitats &c) Regulation 2007 (as amended in 2010). Based on the above assessment the EIA concluded that it is likely that subsea noise will adversely affect marine mammals and as such, the residual impact of noise during construction has been ranked as minor significance.

9.5.5.2 Accidental events: spill of hydrocarbon >10 tonnes

There is the potential that marine mammals could be significantly affected if a large crude oil spill was to occur. As discussed in Section 7.2.1, the probability of a spill >0.1 tonnes occurring during drilling has been estimated as 24%.

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Available data is not sufficient to calculate the probability of a spill >10 tonnes occurring but it is likely to be rare. The frequency of the production flowline failing in open sea is 0.00125 times per year. A diesel spill will rapidly evaporate on release and will naturally disperse in the high energy offshore environment. Modelling, presented in Section 7.3.2, indicates that a diesel spill of 5,830m3 i.e., from a combined loss of inventory from the FPSO and export tanker, will naturally disperse and evaporate within 10 hours. As such, it is not considered that diesel will pose a significant threat to seabirds. A worst case crude oil spill scenario has been modelled to inform the EIA; a full loss of containment if the FPSO and export tanker were to collide. The modelling results are presented in Section 7.3.1. In this scenario, modelling shows that in the event of a worst case (the larger inventory from the export tanker) crude oil loss of 100,000m3 (87,000 tonnes) then depending on the prevailing wind conditions at the time there is a 1% chance of oil beaching along a coastline of one of the countries bordering the North Sea. Trajectory modelling indicates that:

3 With a prevailing wind towards the UK coastline: 86,393m of crude oil could beach on the North Yorkshire coastline

With a prevailing wind towards the nearest international boundary (UK/Norway): 161,742m3 of emulsified crude oil could beach on the Danish coastline Modelling results are presented in Appendix B. Although the region surrounding the Alma development is not considered to be particularly important for marine mammals from the sightings data shown in Table 9-10, pods and individuals have been observed in the area throughout the year. Should a major release of crude oil occur, there is the potential that individuals could be affected. In addition should any oil reach the shoreline, haul out sites for pinnipeds may be impacted. Pinnipeds are particularly sensitive between October and January when they are on land pupping and again between February and March during their annual moult. Neonatal pups are particularly at risk from oil coming ashore. Cetaceans have smooth hairless skins over a thick layer of insulating blubber, so oil is unlikely to adhere persistently or cause a breakdown in insulation. Marine mammals must surface to breathe and they may inhale vapours given off the spilt oil and their eyes may be vulnerable to major pollution. Indirect effects may also be caused through contamination and depletion of food resources. Due to the transient nature of cetaceans, it is likely that individuals not in the immediate area of the spill when it occurs will avoid the area and it is possible that the number of individuals affected could be small. However, if a substantial number of a population where affected there could be knock on effects to breeding and the long-term viability of the population. Recovery rates of land based marine mammals such as seals could be longer particularly if a spill affected a breeding season. It is highly unlikely that a spill of the magnitude discussed above will occur. Mitigation measures outlined in the OPEP and management controls to eliminate spills should prevent any sizeable spills. Given the likelihood of an

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impact occurring is unlikely the EIA concluded that residual significance of the impact is minor after mitigation.

9.6 PROTECTED SITES AND SPECIES

9.6.1 Baseline Data Sources

The following baseline data sources were drawn upon to inform the baseline description:

Gardline Environmental (2011). Alma Field Development Site Survey: Environmental Baseline & Habitat Assessment Survey. Ref 8602

JNCC website www.jncc.gov.uk

Natura in UK Offshore waters: Advice to support the implementation of the EC Habitats and Birds (Johnston et al 2004) 9.6.2 Existing Baseline

There are a number of protected areas (designated under both UK and International legislation) concerned with the marine and coastal environment. The main designations are: special areas of conservation (SAC); special protection areas (SPAs), RAMSAR sites; and sites of special scientific interest (SSSI). The EC Habitats Directive requires member states to designate SACs for the protection of a number of habitats and species listed under Annex I and II of the Directive. The main aim of the EC Habitats Directive is to promote the maintenance of biodiversity by requiring member states to take measures to maintain or restore natural habitats and wild species at a favourable conservation status. Each member state is required to propose a national list of sites for selection as a SAC. Of the 189 European habitats and 788 European species listed in Annexes I and II of the EC Habitats Directive, four habitats and over twenty species are known to occur, or could potentially occur, in UK offshore waters. Areas identified as potential Annex I habitat (PAIH) or areas containing Annex II species may in future been taken forward for selection as SAC. Advisory bodies, such as the Joint Nature Conservation Committee (JNCC), are currently identifying areas of offshore PAIH to be put forward to the government as Special Areas of Conservation (SACs) as part of the Natura 2000 in UK offshore waters programme (Johnston et al. 2004). No protected areas occur within 40km of the development. The closest protected site to the field development is the Dogger Bank possible SAC, which lies approximately 78km south of the southern drill centre (Figure 8-2). The site has been formally recommended to the UK Government by the JNCC but has yet to be submitted to / or approved by the European Commission for designation as a full SAC. The pSAC supports communities typical of sandy sediments, characterised by polychaete worms, amphipods and small clams within the sediments and hermit crabs, flatfish and starfish on the seabed. Sandeels are abundant on the flanks of the bank and provide a food resource for seabirds, cetaceans and other commercial fish species, such as cod. The Dogger Bank region is an important location for the North Sea harbour porpoise

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population and as such they are included as a qualifying feature. Grey and common seals are known to visit the bank and are included as non-qualifying features at the site (JNCC 2011). The Alma site survey data was reviewed to assess the occurrence of habitat types listed on Annex I of the Habitats Directive. The four Annex I habitat types known to occur in UK offshore waters are:

Reefs (stony and biogenic)

Sandbanks which are slightly covered by seawater at all times

Submarine structures made by leaking gases

Submerged or partially submerged sea caves No habitats or species of conservation significance under the UK’s Offshore Marine Conservation (Natural Habitats, &c) (Amendment) Regulations 2010, which implement the requirements of the EC Habitats Directive, were observed (GEL 2011). Annex II Species Of 788 European species listed in Annexes II of the EC Habitats Directive, over twenty species are known to occur, or could potentially occur, in UK offshore waters. These are:

Cetacea - Dolphins, porpoises and whales (all species)

Sturgeon (Acipenser oxyrinchus)

Marine turtles (all species)

Barbel (Barbus barbus)

Grayling (Thymallus thymallus)

Atlantic Salmon (Salmo salar)

Seals – Common (Phoca vitulina) and Grey (Halichoerus grypus)

Shad - Allis (Alosa alosa)and Twaite (Alosa fallax) Of the Annex II species listed above, five species of cetacea and two species of pinniped are found within the vicinity of the project area. Their distribution and sensitivity to the project are discussed in detail in Section 8.5 above. There is a Net Gain zone approximately 7.9km west from the Alma drill centre location (Figure 9-2). This area has been identified as a potential marine conservation zone (MCZ) and could be designated as such in the near future. However, at the present time there is no statutory protection afforded to these areas and it is unlikely that this will come into affect prior to the construction of the Alma development area.

9.6.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed in Table 9-14 have the potential to interact with protected sites and species.

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Table 9-14: Protected sites and species – potential impact identification Project Activity Aspect Potential Impact Construction Anchoring Could affect integrity of protected site Can cause physical injury or Physical presence and Subsea noise disturbance to protected species movement of vessels Discharge of sewage, grey water, food Potential toxic effects on protected waste and drainage water species Can cause physical injury or Subsea noise disturbance to protected species Drilling of wells Discharge of cuttings Could affect integrity of protected site Discharge of chemicals (including WBM) Potential toxic effect on protected Discharge of reservoir hydrocarbons species Discharge of chemicals (including WBM) Physical presence of subsea Installation of flowlines infrastructure and flowlines Could affect integrity of protected site Concrete mattressing and rock protection Installation of FPSO Anchoring Production Physical presence, Discharge of produced water Potential toxic effects through operation and bioaccumulation of chemicals and maintenance of FPSO Discharge of chemicals hydrocarbons in food chain Physical presence and Can cause physical injury or movement of export Subsea noise disturbance to protected species tanker and supply vessels Accidental Events Overboard loss of Could affect the integrity of a protected Dropped objects equipment or waste site Chemical / hydrocarbon release (< 1 tonne) Smothering of protected species Chemical / hydrocarbon Diesel, crude or chemical spill (including Potential affects on integrity of a release (1-10 tonnes) OBMs) protected site Chemical / hydrocarbon release (>10 tonnes)

9.6.4 Mitigation Measures

The potential impacts on protected sites and species are the same as on the baseline physical and biological conditions of the project area, but with national or international consequences. As such, measures to actively mitigate impacts on protected sites and species are similar to those employed to mitigate impacts on the individual components of the environment which the designation

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protects. These are discussed in detail in relevant sections of this ES e.g., seabed conditions (Section 8.4.4), benthic communities (Section 9.2.4), seabirds (Section 9.4.4) and marine mammals (Section 9.5.4).

9.6.5 Residual Impact Significance Assessment

9.6.5.1 Physical disturbance of a protected feature

The Alma development does not lie within a protected area. There are no protected sites within 40km of the development area; the closest protected site is the Dogger Bank pSAC which lies approximately 78km south of the southern drill centre. Due to the distance involved, the project footprint is not expected to overlap with the site. Therefore, the integrity of any protected site is not anticipated to be affected by the Alma development. The impact on protected species of marine mammals and seabirds are discussed in Sections 9.4.5 and 9.5.5 above.

9.6.5.2 Subsea noise

The residual impact assessment for the affect of subsea noise on protected species can be found in Sections 9.5.5.1 above.

9.6.5.3 Accidental events: spill of hydrocarbon >10 tonnes

There is the potential that protected sites and species could be significantly affected if a large crude oil spill was to occur. As discussed in Section 7.2.1 the probability of a spill >0.1 tonnes occurring during construction has been estimated as 24%. The frequency of the flowline failing in open sea is 0.00125 times per year. The impact on protected species of marine mammals and seabirds are discussed in Sections 9.4.5 and 9.5.5 above. Although there are no designated protected sites within 40km of the Alma field, a major crude oil spill caused by a loss of containment due to collision (i.e., the FPSO and export tanker with each other) was modelled as the worst case scenario and the modelling results are presented in Section 7.3.1. In this scenario, modelling shows that in the event of a worst case crude oil loss of 100,000m3 (87,000 tonnes) (the larger inventory from the export tanker) then there is a 1% chance of oil beaching along the coastlines of the majority of countries bordering the North Sea. Trajectory modelling indicates that, depending on the prevailing metocean conditions at the time, there is the possibility for crude oil to beach on the North Yorkshire and/or Danish coastline as summarised below and in Appendix B: As can been seen from Figure 9-3, there are numerous protected sites along the coastlines of those North Sea countries that could be affected by a spill of this magnitude. Should a spill occur that could potentially affect a protected area an intervention response would be required. It is highly unlikely that a spill of the magnitude discussed above will occur. Mitigation measures outlined in the OPEP and management controls to eliminate spills should prevent any sizeable spills. As the likelihood of such a spill occurring is extremely rare the EIA concluded that residual significance of the impact is moderate.

REPORT REF: P1459BA_RN2525_REV0 9-28 21/07/2011 6°0'0"W 4°0'0"W 2°0'0"W 0°0'0" 2°0'0"E 4°0'0"E 6°0'0"E 8°0'0"E 10°0'0"E 12°0'0"E 14°0'0"E 16°0'0"E 60°0'0"N 60°0'0"N 58°0'0"N 58°0'0"N 56°0'0"N

56°0'0"N XW!. 54°0'0"N 54°0'0"N 52°0'0"N 52°0'0"N 50°0'0"N 50°0'0"N

4°0'0"W 2°0'0"W 0°0'0" 2°0'0"E 4°0'0"E 6°0'0"E 8°0'0"E 10°0'0"E 12°0'0"E

Legend Alma Field Development Environmental Statement Median Line Non UK Protected Sites Land Danish Protected Sites Figure 9-3: Oil spill beaching locations in relation Netherlands Protected Sites to protected sites German Protected Sites Date Friday, June 3, 2011 17:16:11 Uisge Gorm FPSO XW Norwegian Protected Sites Projection ED 1950 UTM Zone 31N !. Northern Drill Centre International 1924 !. Southern Drill Centre Spheroid Datum D European 1950 ! Potenital beaching locations Data Source Birdlife International, ESRI, JNCC, World Database of Protected Areas, J:\P1459\Mxd\Environmental Statement\.mxd UK Protected Sites File Reference SAC Beaching Locations & Protected sites v1 dSAC Produced By Rebecca Summons cSAC Checked pSAC Reviewed By Anna Farley SPA Ramsar

10 IMPACTS ON HUMAN ENVIRONMENT

This section describes the existing baseline human environment, the potential impacts arising from the Alma development project thereon, and their mitigation as appropriate. The section also qualifies the significance of any residual impacts. It follows the methodology set-out in Section 4. The human environment has been separated into the following sections:

Commercial fishing (Section 10.1)

Shipping and navigation (Section 10.2)

Other marine users (Section 10.3)

Archaeology (Section 10.4)

10.1 COMMERCIAL FISHERIES

10.1.1 Baseline Data Sources

This section makes use of the following data sources:

MMO fisheries statistics from 2004 to 2009 (MMO 2011)

Fisheries Sensitivity Maps (Coull et al., 2008) 10.1.2 Existing Baseline

The North Sea is home to approximately 230 species of fish, thirteen of which are the main targets for commercial (direct human consumption) and industrial fisheries (where the catch is converted into fish meal and oil) (OSPAR Commission 2000). For the purposes of this EIA “commercial fishing” includes all fishing for commercial gain (i.e., commercial + industrial). Section 9.3 provides more information on the fish species present in the Alma development area. Major UK and international fishing fleets operate in the North Sea, producing more than 3 million tonnes per annum and contributing approximately 4% of the world’s fishery production (Coull et al., 2008). Fleets target both pelagic and demersal fish stocks, as well as significant shellfish stocks such as the commercially valuable Norway lobster (Nephrops). An assessment of the fishing industry in the region of the development has been derived from Marine Management Organisation (MMO) catch statistics for the period 2004 to 2010 (MMO 2011). Statistics were obtained for the ICES rectangle 41F2, within which the Alma development area is located, and surrounding rectangles. The data provides details on receiving port, species landed (live weight in tonnes) and value of species. The data considers all vessels using UK ports and UK vessels using foreign ports but does not take into account foreign vessels landing at foreign ports.

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The Alma development area is not considered to be a commercially important ground for pelagic and demersal species. Analysis of the statistics indicates that:

Approximately 147.5 tonnes of fish and shellfish, worth approximately £130,233 are landed each year from ICES rectangle 41F2.

Overall catch (live weight tonnes) is dominated by the pelagic species herring (Clupea harengus) (447 tonnes in 6 years).

Herring, as well as the demersal species lemon sole (Microstomus kitt), and haddock (Melanogrammus aeglifinus) are the most commercially valuable species targeted in the region.

The shellfish fishery is of relatively low value (approximately £4,700 per year), with the majority of the catch represented by Norway lobster (Nephrops norvegicus), scallops and low value squid (Loligo vulgaris). An idea of the importance of commercial fishing in the immediate vicinity of Alma can be gained by comparing ICES rectangle 41F2 with those in the surrounding area (e.g., 40F1, 40F2, 41F1, 42F1 and 42F2). This comparison is tabulated in Table 10-1 below and illustrated in Figure 10-2. The table indicates that ICES rectangle 41F2 is the most productive and commercially valuable area for herring in the region, but that overall the commercial fishery is of moderate to low value in comparison to other areas. The relative value of the fisheries within ICES rectangle 41F2, when compared to the rest of the North Sea, is low (Coull et al. 1998). Table 10-1: Value (£) of landing for the Alma development area and surrounding region (2004 – 2009) ICES Rectangle Herring Lemon Sole Plaice Haddock Nephrops 40F1 32,166 39,423 23,392 108,757 159,255 40F2 43,832 315,153 315,207 8,556 6,190 41F1 - 130,531 30,308 126,942 2,048,093 42F1 52,974 589,554 58,118 239,023 2,607,962 41F2 118,677 321,514 59,519 186,439 22,315 42F2 - 295,900 45,220 198,713 9,645 Grand total (2004 – 2009) from all rectangles 247,649 1,692,075 531,764 868,430 4,853,460 Catch from 41F2 as a percentage of total species specific catch from the area 47.9% 19.0% 11.2% 21.5% 0.5% Average annual catch 19,780 53,586 9,920 31,074 3,720 from 41F2 Source: MMO (2011) Fishing activity in the vicinity of Alma is generally low at the beginning of the year (January to March). This rises to a peak in August before falling off again towards the end of the year with a small peak in December (Figure 10-1). The bulk of the catch from ICES rectangle 41F2 (live weight tonnes) in 2004-2009 was landed at either Scheveningen in The Netherlands (374 tonnes) or Peterhead, Aberdeenshire (303 tonnes). A total of approximately 66 tonnes was also landed in Eyemouth, Berwickshire during this 6 year period.

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The DECC Online Maritime Data GIS system (Maritime Data 2011) indicates that a moderate number of fishing vessels are also active in the area. The development area is within an area of moderate fishing effort (based on days fished). Figure 10-2 shows the average annual catch (tonnes) and the average annual value of catch (£) in the Alma development area and surrounding region for the six year period 2004 – 2009. Figure 10-1: Seasonal variation in fishing activity (2004-2009)

Source: MMO (2011)

REPORT REF: P1459BA_RN2525_REV0 10-3 21/07/2011 1°0'E 2°0'E 3°0'E 1°0'E 2°0'E 3°0'E Alma Field Development Environmental Statement Figure 10-2: Average annual catch and value for Alma (2004-2009) . .. Legend

Median Line Live weight (tonnes)

UKCS Block 0-50

XW Uisge Gorm FPSO 50-100 57°0'N 57°0'N 57°0'N 57°0'N !. Northern Drill Centre 100-200

!. Southern Drill Centre 200-250

Value (£)

0-50,000

50,000-100,000

100,000-200,000

200,000-300,000

300,000+

!. !. !.XW !.XW 56°0'N 56°0'N 56°0'N 56°0'N

Date Friday, July 1, 2011 14:36:57

Projection ED_1950_UTM_Zone_31N

Spheroid International_1924

Datum D_European_1950

Data Source UKDeal, MMO

File Reference J:\P1459\Mxd\Environmental Statement\.mxd Figure 10-2 Commercial Fisheries

Produced By David Cook Checked Reviewed By Anna Farley 55°0'N 55°0'N

10.1.3 Potential Impact Identification

The EIA identified that during the project life-cycle the activities listed in Table 10-2 have the potential to interact with commercial fishing. Table 10-2: Commercial fishing – potential impact identification Project Activity Aspect Potential Impact Construction Increased vessel activity in region Exclusion from fishing grounds Physical presence and Exclusion zones Potential collision risk movement of vessels Anchor mounds could snag Anchoring fishing gear Drilling of wells Discharge of cuttings Concrete mattressing and rock Could snag fishing gear Installation of flowlines placement Trenching and backfill Production Physical presence, operation and Presence of FPSO and anchors Exclusion from fishing grounds maintenance of FPSO Exclusion zones Potential collision risk Increased vessel activity in region Physical presence and Exclusion from fishing grounds movement of export tanker, Exclusion zones Potential collision risk support and supply vessels Physical presence of subsea Presence of subsea infrastructure Could snag fishing gear infrastructure and flowlines Accidental Events Overboard loss of equipment or Dropped objects Could snag fishing gear waste Chemical / hydrocarbon release (< 1 tonne) Potential decrease in catch if Chemical / hydrocarbon release Diesel, crude or chemical spill stocks affected (1-10 tonnes) (including OBMs) Damage to boats and gear Chemical / hydrocarbon release (>10 tonnes)

The EIA concluded that the majority of activities have the potential to impact commercial fisheries. Typically, impacts are of low significance, with a site- specific to low spatial extent. The likelihood, severity and significance of the impacts have been assessed in Sections K of Appendices A2 and A3 and Section I of Appendix A4.

10.1.4 Mitigation Measures

Potential impacts requiring mitigation fall into two main categories:

Those that could impact directly on fishing (e.g., exclusion zones, hazards which could snag nets)

Those that affect the fish stocks.

Measures to mitigate the impact on fish species (through reduced water quality and toxic effects of chemicals) have been previously outlined in Section 9.3.4. Measures relating to minimising the seabed footprint are outlined in Section 8.3.4 and have not been repeated here. They have not been repeated in full here but are summarised in Table 12-2 and provided in Appendix A. The mitigation measures of direct relevance to commercial fisheries are detailed below:

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To minimise snagging risks to fishing gear, a debris clearance survey will be conducted at the end of the construction phase and any significant objects will be removed. If the object cannot be retrieved a PON2 will be submitted to the DECC.

To minimise collision risks, a 500m safety exclusion zone around the drilling rig will be enforced. The drilling rig and construction vessels will be appropriately lit, sound warnings will be broadcast in poor visibility and all vessels will comply with IMO standards.

Via the Kingfisher fortnightly bulletins, Notices to Mariners and, where appropriate, VHF radio broadcasts users of the sea will be notified of:

The presence and intended movements of construction vessels

The presence of exclusion zones

The presence of new structures on the seabed and mattressed areas of seabed

All new wellheads will be within a 500m safety exclusion zones established around the southern and northern drill centres. However, all wellheads are designed to be fishing friendly to designs approved by the Scottish Fishermen’s Federation (SFF).

Field construction and operation vessels movements will be minimised.

A 500m safety exclusion zone will be enforced around the FPSO for the duration of field life. The FPSO will be appropriately lit, sound warnings will be broadcast in poor visibility and all support vessels in the field during production will comply with IMO standards. 10.1.5 Residual Impact Significance Assessment

Once mitigation measures are applied, the following activities have been progressed for residual impact significance assessment (see Section K of Appendix A2 and A3 and Section I of Appendix A4).

10.1.5.1 Exclusion zones

Three permanent 500m radius safety exclusion zones will be established around the northern and southern drill centres and the FSPO. The safety zones will be enforced by a guard vessel. There is potential for fishing vessels to be displaced from their fishing grounds due to the presence of the new zones. Fishing activity in the region of Alma is moderate (based on days fished data, see above) and any impact will be restricted to the duration of field life (10 years). However, as the exclusion area is small in comparison to the wider CNS fishing grounds it is unlikely that any impact will be significant. Overall, the conclusion of the assessment was that the field development will have a minor residual impact on commercial fisheries.

10.1.5.2 Snagging hazards

A number of subsea structures and residual footprints have the potential to present a snagging risk to fishing vessels. For example, anchor mounds created by the drilling rig, the manifold, wellheads and flowlines. Structures are designed to be fishing friendly i.e., they have raked sides that deflect trawl boards and will be within an enforced 500m safety zone. Therefore, the

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mitigation measures are considered to reduce the risk of fishing gear snagging to an acceptable level and negate any residual impact.

10.1.5.3 Accidental Events: spills of hydrocarbons (>10 tonnes)

A major crude oil spill has the potential to damage fishing vessels passing through the project location at the time of the event and has the potential to cause a decrease in catch if fish stocks are affected. It is expected that if boats are present in the area at the time of a spill they will be able to avoid the slick so it is considered highly unlikely gear or boats will be damaged. However, vessels may be excluded from the affected area during the clean-up operations. Generally, for short periods of time the fishing industry can relocate to other grounds without any detrimental impacts to catch, but a spill that affects large areas of sea may make it harder to relocate. It fish stocks are contaminated they make take a number of years to recover and fishing grounds could be closed with substantial loss of income for industry. Experience from major spills has shown that the long-term effects on wild fish stocks are unlikely because the normal over-production of eggs provides a reservoir to compensate for any localised losses. However, there could be a loss of market confidence as people may be unwilling to buy fish caught in a contaminated area. Although the potential impacts could be of major significance to the fishing industry the fact that a spill of the magnitudes discussed above is highly unlikely has meant that the EIA concluded the residual impact is of minor significance.

10.2 SHIPPING AND NAVIGATION

10.2.1 Baseline Data Sources

This section makes use of the following data sources:

Technical report on existing activities within SEA 2 (DTI 2001e)

Charting Progress 2: The State of UK Seas - a report by the UK Marine Monitoring and Assessment Strategy community (UKMMAS 2010)

Consent to Locate - Alma (Technical Note) (Anatec 2011) 10.2.2 Existing Baseline

Shipping activity is economically important for the east coast regions of England and Scotland and provides links with northern Europe from the Port of Tees and Hartlepool and from ports in the Firth of Forth, e.g., Rosyth and Edinburgh (UKMMAS 2010). The CNS experiences moderate levels of shipping traffic associated with a number of major ports located along the coast. These include international ports, import/export facilities, roll on – roll off (ro-ro) facilities, ship building yards, container and ferry services, bases for the offshore oil and gas industry and commercial fishing facilities. The majority of routes transiting the Alma field have an average of 0.5 to 1 daily vessels passages, with some routes experiencing daily passage of 1-10 vessels (DTI 2001e). As can been seen from Tables 10-3 and Figure 10-3 below, there are fourteen ship routes that pass within 12 nautical miles (nm) of the Alma development.

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Table 10-3: Ship routes Route Description FPSO Northern Drill Southern Drill Ships % of No. Centre Centre Per Total CPA Bearing CPA Bearing CPA Bearing Year (nm) (°) (nm) (°) (nm) (°) 1 Humber-Boknafjorden b* 1.2 299 0.5 119 0.6 299 50 5% 2 Aberdeen-Esbjerg* 3.2 16 2.8 16 4.6 16 70 7% 3 Norway S-Tees* 3.4 147 4.9 147 3.2 147 70 7% 4 Aberdeen-Fife* 5.2 204 5.3 204 3.7 204 26 3% 5 Volve Field-Rotterdam* 5.6 78 7.0 78 7.1 78 62 7% 6 Lerwick-Amsterdam Direct 5.6 242 4.6 242 3.9 242 8 1% 7 Norway S-Seaham* 5.9 326 4.4 326 6.1 326 10 1% 8 Humber-Boknafjorden a* 6.6 296 4.8 296 5.9 296 200 21% 9 Canada-Hamburg* 7.1 214 6.9 214 5.5 214 100 11% 10 Hamburg-Moray Firth* 7.1 214 6.8 214 5.4 214 25 3% 11 Tyne-Norway S* 7.2 330 5.8 330 7.6 330 20 2% 12 Tyne-Kattegat* 8.2 157 9.5 157 7.7 157 235 25% 13 Hamburg-Kirkwall 9.9 41 10.4 41 11.6 41 15 2% 14 Montrose-Esbjerg* 11.5 194 11.8 194 10.0 194 45 5% TOTAL 936 100% * Where two or more routes have identical Closest Point of Approach (CPA) and bearing they have been grouped together. In this case, the description lists the sub-route with the most ships per year Source: Anatec (2011) Figure 10-3: Shipping Route Positions within 10nm of Alma Locations

Source: Anatec 2011

The fourteen shipping routes are trafficked by an estimated 936 ships per year passing within 12nm of the three Alma locations. This corresponds to an average of 2 to 3 vessels per day. The majority of these vessels are either cargo ships or tankers, with the highest percentage of these vessels being 1,500 - 5,000 tonnes in size. The only route to pass within 2nm of Alma (Route 1) is used by an estimated 50 vessels per year between Humber and Boknafjorden in Norway. The route passes northwest of the FPSO location at a mean distance of 1.2nm, southeast of the northern drill centre at a mean distance of 0.5nm and northwest of the southern drill centre at a mean distance

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of 0.6nm. The next closest mean route position passes over 2nm from the Alma locations (Anatec 2011). In addition, a moderate number of fishing vessels will be present in the area surrounding the Alma development (Maritime Data 2011). Collision Risk The likelihood of collision with the FPSO has been calculated taking into account the fact that the FPSO will be turret moored and is therefore assumed to freely weathervane bow-on into the wind direction. The collision frequency per wind direction was then calculated and the results then factored by the annual probability of each wind direction (Anatec 2011). The annual ship/installation collision frequencies (distributed by impact energy) are shown in Table 10-4 below. Table 10-4: Ship/Installation collision frequencies estimated for Alma FPSO Impact Energy (MJ) Annual Collision Frequency 0 - 20 9.4E-06 20 - 50 3.1E-05 50 - 100 5.5E-05 100 - 200 4.7E-05 ≥ 200 3.7E-05 Total 1.8E-04 Source: Anatec 2011

Therefore, the annual ship collision frequency for the Uisge Gorm FPSO at Alma is estimated to be 1.8 x 10-4 (Anatec 2011).

10.2.3 Potential Impact Identification

The EIA identified that during the project life-cycle the activities listed in Table 10-5 have the potential to interact with shipping and navigation. However, the likelihood of an impact occurring is unlikely, restricted to the local region and is likely to be low in magnitude. Any impacts from the drilling of wells and the presence of pipeline laying vessels (PLV) will be short in duration but the presence of the FPSO for ten years or more may have a longer lasting effect on shipping. A 500m temporary safety exclusion zone will be established around the PLVs.

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Table 10-5: Shipping and navigation – potential impact identification Project Activity Aspect Potential Impact Construction Exclusion zone could impede Physical presence and movement of Physical presence and shipping lanes vessels movement of vessels Increased collision risk Production Physical presence, operation and Presence of FPSO and maintenance of FPSO anchors Exclusion zone could impede shipping lanes Physical presence and movement of Increased vessel activity in export tanker and supply vessels region Potential collision risk Accidental Events Overboard loss of equipment or waste Dropped objects Could cause hazard to shipping Chemical / hydrocarbon release (>10 Diesel, crude or chemical spill Damage to vessels tonnes) (including OBMs) Restrictions on shipping lanes

10.2.4 Mitigation Measures

Mitigation measures will be as per Section 10.1.4 with the addition of the following:

A 500m safety exclusion zone around the FPSO and drilling rig will be enforced.

All construction and operation vessel movements will be kept to a minimum.

The FPSO, drilling rig and support vessels will be appropriately lit and sound warnings will be broadcast in poor visibility.

Other users of the sea will be notified of the presence and intended movements of vessels associated with the development through Kingfisher fortnightly bulletins, notices to mariners, and regular VHF radio broadcasts.

All vessels associated with the development will follow IMO Standards and will be properly marked.

An OPEP will be in place to mitigate any spills and pipelines will be tested to ensure integrity.

EnQuest will have a collision risk management plan in place for the proposed development, compliant with IMO standard requirements. 10.2.5 Residual Impact Significance Assessment

Once mitigation measures are applied, the following activities have been taken forward for the residual impact significance assessment (see Sections L of Appendices A2 and A3 and Section J of Appendix A4).

10.2.5.1 Physical presence and movement of vessels

The nearest shipping lane is within 2nm of the Alma development. Some shipping will be displaced from the immediate vicinity of the development; however there is ample sea room to do so. The 500m safety exclusion zone around the drilling rig and FPSO is intended to prevent potential collisions with any vessels that may be in the area. This will be enforced by a guard vessel.

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As such, it is concluded that the presence and movement of vessels will have no residual impact on shipping and navigation.

10.2.5.2 Accidental events: spill of hydrocarbons (>10 tonnes)

Spill modelling (Section 7 and Appendix B) shows that in the event of a total loss of containment from the FPSO and/or export tanker (due to collision with each other); depending on the prevailing wind conditions at the time, large areas of the North Sea area could potentially be affected if no intervention measures are taken. However, an incident of this magnitude is unlikely. If the spill is extensive then shipping lanes in the region could be closed to facilitate oil spill response operations to be implemented. Similarly, it is possible that shipping lanes could be routed around the affected area. There is the risk of economic impacts on shipping associated with longer routes and delays. Due to the rarity of such an event, the residual impact has been assessed as of minor significance.

10.3 OTHER MARINE USERS

10.3.1 Baseline Data Sources

Sources of data used in this section include:

Data from the Crown Estate on offshore windfarm areas and marine aggregate dredging sites (Crown Estate 2011)

Oil and gas infrastructure data (UKDeal 2010)

Atlas of recreational boating (RYA 2008)

Cables data (KISCA 2010)

Admiralty charts for the area showing military practice and exercise areas 10.3.2 Existing Baseline

Other marine users are all other users of the marine environment, not including commercial fisheries and shipping which have been assessed separately in this report. This includes (but is not limited to) recreational users, other oil and gas developments and wind farm installations. Given the distance of the Alma field from the nearest landfall (i.e., 274km from the Northumbrian coastline) the majority of activity within the area is associated with offshore oil and gas exploration and production (See Figure 10-4). The following oil and gas infrastructure is located within 40km of the Alma development area;

123 wells (see Table 10-6); one platform (Clyde), one FPSO (Janice Alpha) and 4 pipelines.

The nearest platform to the development is the Clyde platform, located 38km northwest of the northern drill centre.

One pipeline transects Block 30/24. This is the Norpipe system Ekofisk 2/4J to Teeside oil pipeline which runs through the north east corner of the Block, 15.5km north-west of the northern drill centre.

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Table 10-6: Wells within 40km of the development Activity Status Completed Suspended Plugged and abandoned Unknown TOTAL Appraisal 7 6 8 1 22 Exploration 4 2 45 1 52 Development 18 16 15 0 49 Total 29 24 68 2 123

Other marine users in the vicinity of the project include:

Seven telecommunications cables within 40km of the project area. The closest cable is the Norsea AS cable which links the Valhall complex and the Clyde platform. At its closest point the cable is 28km north east of the Uisge Gorm FPSO.

The Dogger Bank Round 3 licensed wind farm zone is located 53km to the south of the southern drill centre. 6 Recreational boating - a lightly used recreational sailing route passes through the centre of Blocks 30/24 and 30/25, 6km northwest of the northern drill centre. There are several yachting routes, general sailing areas and racing areas near the coast but the development is far enough offshore for general sailing not to occur in the vicinity (RYA 2008).

Marine aggregate dredging site, Area 466/1 application area, licensed to Cemex UK Marine Ltd, is the closest to the project area, situated 139km southwest of the southern drill centre.

There are no military practice and exercise areas (PEXA) or munitions dumping sites within 100km of the project area.

6 Light Recreational Route - as defined in the UK Coastal Atlas of Recreational Boating, RYA 2008

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10.3.3 Potential Impact Identification

The EIA identified that during the project life cycle the activities listed below have the potential to interact with other marine users (Table 10-7). Table 10-7: Other marine users’ potential impact identification Project Activity Aspect Potential Impact Construction Localised displacement of other Physical presence and marine users movement of vessels Increased collision risk Physical presence and movement of vessels Anchors could impact other Anchoring existing infrastructure Increased collision risk Production Physical presence, operation and Presence of FPSO and maintenance of FPSO anchors Localised displacement of other marine users Physical presence and movement of Increased vessel activity in export tanker and supply vessels region Increased collision risk Accidental Events Overboard loss of equipment or waste Dropped objects Could cause hazard to shipping Chemical / hydrocarbon release (< 1 tonne) Diesel, crude or chemical spill Damage to vessels Chemical / hydrocarbon release (1-10 (including OBMs) tonnes) Restricted access

Chemical / hydrocarbon release (>10 tonnes)

The likelihood of activities affecting other marine users was assessed as being unlikely given the historical use of the development area for oil and gas activity. If impacts were to occur they would be relatively site specific, low in magnitude with a short-term duration.

10.3.4 Mitigation Measures

Marine users will be notified of the presence and intended movements of construction vessels and the presence of new structures via the Kingfisher fortnightly bulletins, Notices to Marine and, where appropriate, VHF radio broadcasts. In addition, EnQuest will have a collision risk management plan in place for the proposed development, including the deployment of a guard vessel on station.

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Legend Alma Field Development Environmental Statement Median Line 10 Land Figure -4: Other Marine Users UKCS block Date Tuesday, June 14, 2011 12:49:04 Projection ED_1950_UTM_Zone_31N XW Uisge Gorm FPSO Spheroid International_1924 !. Northern Drill Centre Datum D_European_1950 !. Southern Drill Centre Data Source The Crown Estate, ESRI, UKDeal, RYA, KISCA J:\P1459\Mxd\Environmental Statement\.mxd FPSO File Reference XW Figure 10-4 Other Marine Users )" Platform A Well Produced By Rebecca Summons Pipeline Checked Anna Farley Cable routes Reviewed By Hydrocarbon Field

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10.3.5 Residual Impact Significance Assessment

Mitigation measures are considered to be sufficient to reduce the impact on other marine users in the area. One activity has been taken forward for the residual impact significance assessment (see Sections M of Appendices A2 and A3 and Section K of Appendix A4).

10.3.5.1 Accidental events: spill of hydrocarbons (>10 tonnes)

Spill modelling (Section 7 and Appendix B) shows that in the event of a total loss of containment from the FPSO and/or export tanker (due to collision with each other); depending on the prevailing wind conditions at the time, large areas of the North Sea area could potentially be affected if no intervention measures are taken. Oil spill modelling indicates that oil has the potential to beach along the coast. In this situation there is the potential that near shore recreation could be affected if restrictions are imposed to assist with response operations. There may also be knock-on effects on the tourist industry if the spill beaches in substantial quantities. As the likelihood of such an event occurring is highly unlikely, the EIA concluded that the residual impact is of minor significance.

10.4 ARCHAEOLOGY

10.4.1 Baseline Data Sources

Prehistoric Archaeology Data concerning the general submarine archaeology of the North Sea was compiled as part of the Strategic Environmental Assessment for areas SEA2 and SEA3 (Flemming 2002). In addition, some information is available under the aegis of the Aggregates Levy Sustainability Fund (ALSF). This represents a pilot study and is currently restricted to near coastal areas (Wessex Archaeology 2008). Historic Remains Information on the status of wrecks is available through the Maritime and Coastguard Agency (MCA 2011).

10.4.2 Existing Baseline

10.4.2.1 Prehistoric Archaeology

As a result of glaciation episodes peaking at about 280,000 yrs before present (B.P.), 150,000 yrs B.P. and 20,000 yrs B.P., the sea bed of what is now the North Sea has been repeatedly exposed and there is significant evidence that areas of the North Sea not covered by ice were habitable. While older remains (>100,000 yrs) are unlikely to have been preserved as far north as Alma, as the area was glaciated prior to this, more recent artefacts may be present. At its greatest extent, some 15,000yrs B.P. the so-called Doggerland may have extended as far north as 61°N, with the Alma area remaining as dry land for about 5000 years. It is possible, therefore, that individual artefacts, such as stone tools, or remains of settlement sites could be encountered during

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operations at Alma. If properly reported and conserved such remains could provide significant information concerning early human development in the Doggerland region. It is likely that any sites discovered will be within the jurisdiction of the Ancient Monuments and Archaeological Areas Act 1979. While this act is primarily land based, it has also been applied to provide some protection for underwater sites. The Act provides for the scheduling of ‘monuments’, which encompasses buildings, structures or work, cave or excavation, vehicle, vessel, aircraft or other movable structure. In order to be eligible for scheduling, a ‘monument’ must be of national importance. Geophysical and geotechnical survey results (Gardline 2011) do not show any anomalies typically associated with archaeological sites.

10.4.2.2 Historic Remains

Throughout the historical period there have been important trade and other routes across the North Sea. While the majority of wrecks resulting from natural events (storms etc) are likely to be coastal in nature some may have occurred in deeper water. The more likely cause of deep water wrecks (including aircraft remains) is wartime activity. Wreck material (broadly any artefact on the seabed as a result of once being on board of or part of a vessel) is presumed to have an owner irrespective of date of loss. It is a legal requirement (under section 236 of the Merchant Shipping Act 1995) that recovered wreck material should be reported to the Receiver of Wrecks. Three key pieces of legislation (MCA 2011) applicable to the protection of wrecks in UK waters are: Protection of Wrecks Act 1973 This act provides for

Protection for designated wrecks which are deemed to be important by virtue of their historical, archaeological or artistic value.

Protection for wrecks that are designated as dangerous by virtue of their contents (e.g. ammunition transporters). The Protection of Military Remains Act 1986

This Act makes it an offence to interfere with the wreckage of any crashed, sunken or stranded military aircraft or designated vessel without a licence. This is irrespective of loss of life or whether the loss occurred during peacetime or wartime. All aircraft which have crashed while on military service (including non-UK) receive automatic protection, but vessels must be individually designated.

Sites may be designated as Protected Places (automatic for military aircraft, but for vessels requires designation by name, although the location may not be known) or as Controlled Sites.

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Ancient Monuments and Archaeological Areas Act 1979

As per Section 9.4.2.1 above, is possible that any wrecks discovered will be within the jurisdiction of the Ancient Monuments and Archaeological Areas Act 1979. In conclusion, there are no known wreck sites (or any other historical remains) within the Alma area and no indication from the survey data (GEL 2011) that any such sites are likely to be present. If present remains may be fragmentary, particularly where these are a result of wartime activity. Part of the reason for protection of such sites is the risk of munitions being present in the vicinity of the wreckage. Unexploded munitions are not rendered safe on immersion in water, and may become dangerously unstable.

10.4.3 Potential Impact Identification

The EIA has identified that during the project life cycle, the activities listed below have the potential to interact with archaeology (Table 10-8). Table 10-8: Archaeology potential impact identification Project Activity Aspect Potential Impact Construction Physical presence and movement of Anchoring vessels Physical damage to existing Physical presence of subsea and undiscovered archaeology Installation of flowlines infrastructure and flowlines Trenching and backfill Production Physical presence, operation and Presence of FPSO and Physical damage to existing maintenance of FPSO anchors and undiscovered archaeology Accidental Events Physical damage to existing Overboard loss of equipment or waste Dropped objects and undiscovered archaeology

The impact of disturbance of an archaeological site is related to the cultural value of a site. This is likely to be increased if a site:

Establishes evidence of human occupation in areas where there was no previous evidence

Contains examples of previously unknown or poorly preserved artefacts

Is of historical significance Uniquely among environmental impacts the discovery of archaeological remains provides an opportunity for positive (i.e., beneficial) impact if such remains are promptly reported and made available for preservation. It is not possible to predict the finding of submerged pre-historic sites. However, if found such discoveries will be of inestimable importance to our understanding of the early settlement of North West Europe. Correct recording and preservation of any artefacts or remains found is both a legal obligation and would be likely to have a high positive publicity value.

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10.4.4 Mitigation Measures

The British Marine Aggregate Producers Association (BMAPA) has produced a protocol for reporting finds of archaeological interest (Wessex Archaeology 2005). This has the specific aim of reducing adverse effects of marine aggregate dredging on the historic environment. However, it is equally applicable to other industries working in the North Sea. These protocols will be followed in the event of discovery of artefacts on the seabed, which could potentially be of archaeological significance.

10.4.5 Residual Impact Significance Assessment

It is unlikely that any remains of archaeological significance exist within the Alma area. However, in the unlikely event of an unforeseen site discovery, the proposed mitigation measures would ensure damage to the site would be minimised and the nature of the discovery properly reported. It is therefore likely that any damage would be of minor significance, while the value of the discovery may be of moderate/major (positive) significance.

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11 CUMULATIVE AND INDIRECT IMPACTS

As discussed in Section 4.2, the EIA has given consideration to cumulative and indirect impacts and interactions. The definitions of these three types of impact overlap, generally without any agreed and accepted definitions. For the purposes of this assessment, the definitions proposed by the European Commission (1999) have been used. The definitions are as follows:

Indirect Impacts (secondary impacts) – Impacts on the environment, which are not a direct result of the project, often produced away from or as a result of a complex pathway.

Cumulative Impacts – Impacts that result from incremental changes caused by other past, present or reasonably foreseeable actions together with the project.

Impact Interactions – The reactions between impacts whether between the impacts of just one project or between the impacts of other projects in the area. It is difficult to quantify indirect impacts due to the project but where possible this was undertaken as part of the main EIA. For example, the potential for chemicals to bioaccumulate up the food chain and affect the top predators such as seabirds and marine mammals. In addition, the EIA also considered cumulative impacts from similar activities within the project e.g., the combined effects on habitat loss from numerous types of seabed disturbance. The results of this assessment are therefore discussed in Sections 8, 9 and 10 and in Appendix A. This Section focuses on the potential for cumulative and indirect impacts and interactions relative to Alma and:

Past and future oil and gas developments (Section 11.1)

Other seabed/marine users e.g., commercial fishing, wind farms, marine aggregate extraction (Section 11.2)

Climate change (Section 11.3)

11.1 OTHER OIL AND GAS DEVELOPMENTS

The Alma development field lies in a mature oil and gas producing area within the CNS. Formerly called the Argyll field, it was discovered in 1971 and brought on stream as the UK’s first offshore oilfield in 1975 before being decommissioned in 1992 (DTI 2001c). The Argyll field was renamed Ardmore and redeveloped in 2003 before again being decommissioned in 2008. There is little current existing infrastructure in the immediate area of the development with the nearest oil and gas activity at the Clyde platform 40.5km to the north- west. However, the long-established, and on-going, oil and gas exploration and production activities of the wider region, gives rise to the potential for cumulative environmental impacts.

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It is possible that, in future, EnQuest may drill an additional production well in the Galia field, situated within Block 30/24 (Figure 11-1). If the well goes ahead it would be tied-back to the northern drill centre via a new flexible production flowline and control umbilical. Construction of the well and flowline will probably be along the same lines as the wells and flowlines in the Alma development, with the exception that the production flowline from Galia to the northern drill centre will be trenched. The project will require a full EIA, whether as an Addendum to the Alma Field ES or as a separate field ES in its own right. However, it can be assumed that the tie-back would have the following seabed footprint:

Anchor mounds and scars from a new drilling rig location affecting 2,600m2 of seabed

Trenching and backfill of the new 6km flowline would affect approximately 12,000m2 of seabed

500m radius safety exclusion zone established around the wellhead EnQuest are not aware of any other new developments in a 40km radius of the Alma development. Figure 11-1: Galia production well in relation to the wider Alma development

Note: Image is for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure

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11.1.1 Deterioration in local air quality

The EIA concluded that the meteorological conditions in the CNS were of sufficient strength to enable rapid dispersion and dilution of SOx and NOx emissions from construction and production activities. Air dispersion modelling indicated that gas concentrations would be significantly below guideline levels for human health and environmental protection within 500m of the discharge point i.e., from either a vessel, rig or FPSO (see Section 8.1.5.1). The majority of the Alma construction and production emissions will occur in the vicinity of the proposed FPSO, 40.5km from the nearest existing installation and 273km from the nearest coastline. In conclusion, Alma is considered to be sufficiently distant from any planned or existing developments such that a cumulative impact of emissions on air quality is unlikely to occur. The effects of the gases on the Alma workforce are dealt with under occupational health regulations and again are out of scope of this assessment. In addition, the generally windy offshore conditions will aid in the dispersion of gases and as such cumulative impacts of atmospheric emissions from the development on regional background levels are considered insignificant.

11.1.2 Deterioration in water quality

During construction and production, there is likely to be chemical discharges including discharges of WBM. The chemicals discharged are relatively benign, the majority being risk assessed by the CEFAS as HQ colour band Gold or OCNS category E. These are categories for products that present the lowest hazard to the environment. Residual currents are such that chemical discharges are likely to be rapidly diluted and dispersed (see Section 8.2.5). The discharge of these chemicals will be short lived and wells will be drilled sequentially reducing any combined toxic impacts. Therefore, no cumulative impacts on water quality are expected during the construction and production phases of the Alma development with the other installations in the vicinity of the development. All of the five installations within 50km of the Alma project area (Clyde, Auk A, Fulmar AD, Ekofisk and Judy) discharge produced water to the marine environment (DECC 2011). At Ekofisk, which is in the Norwegian sector of the North Sea, a purification process is used onboard the platform which reduces hydrocarbon content from 30mgl-1 to only 2 to 4mgl-1 (ConocoPhillips 2011). All UK discharging facilities comply with the 30mgl-1 regulatory standard for produced water. Under normal operating conditions, all produced water from the Alma development will be re-injected into the water injection wells. It is only if the system trips, that there is a possibility that produced water will be discharged overboard from the FPSO. Historic research has shown that, due to the rapid dilution, low concentrations and low toxicities of contaminants in produced water, discharges in the North Sea have low potential for biological impact (Wills 2000). Dilutions required for no observed effect concentration (NOEC) are achieved within five minutes, within 10m to 100m from the discharge point. As the nearest of the five platforms to Alma is 40.5km (i.e., Clyde), it is likely that there will be little or no residual hydrocarbon contamination, during normal operational activities, from other developments around the project area,

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therefore cumulative impacts are not expected. In addition, although the FPSO will be present on site for the field life (10 years), during this time all sewage and food waste is macerated before being discharged overboard. Discharges from visiting vessels will undergo the level of treatment required by shipping regulations. Given the mitigation measures in place and the distance to the nearest discharging facility (Clyde), cumulative effects on water quality are unlikely.

11.1.3 Disturbance of seabed sediments

As discussed in this document, the Alma field development will disturb 0.04km2 of seabed (see Section 6.1.3.4). The EIA has concluded that the development will have a minor impact on seabed sediments. Disturbance may be visible for up to 5-10 years after construction in the form of anchor/chain footprints, or the presence of cuttings piles. However, in general, although disturbed, the composition of surface sediments in the development area will remain unchanged. In addition, given background levels of contamination associated with the previous use of the area for oil and gas development, levels of hydrocarbon contamination are not expected to increase above existing historical levels. No lasting effect on seabed conditions is expected. It can be assumed that a similar level of disturbance will be observed at the other field developments planned for the CNS. Generally, the development projects are widely spread and footprints will not overlap. It is possible cumulative impacts relative to discharges from neighbouring oil and gas facilities operating contemporaneously may arise. However, the closest discharging facility (Clyde) is over 40km from Alma, suggesting a low potential for cumulative impacts.

11.1.4 Disturbance of habitats or species

Drill cuttings There are no other oil and gas developments within 40km of Alma which will be under construction at the same time as the Alma development. Although the drill cuttings piles for the Alma wells (at their respective drill centres) have the potential to overlap, there is not considered to be any potential for cumulative impacts on habitats or benthic species as a result of this aspect of the development in combination with any other development. Pipeline burial The seabed in immediate vicinity of the Alma development is likely to be visibly disturbed on completion of trenching, backfilling and deployment of anchors from the pipeline installation vessel. On retrieval, the anchors are expected to leave a small area of disturbance, much of it which will comprise mobile/loose sediments rather than clay. As there are no other oil and gas developments within 40km, it is unlikely that there will be any cumulative impacts from this aspect of the development.

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Subsea noise Piling noise from Alma is addressed in Section 9.5. As there are no other oil and gas developments within 40km, it is unlikely that there will be any cumulative impacts from this aspect of the development.

11.1.5 Transboundary impacts

The proximity of the development to the UK-Norway median line (closest point 18.5km) also means that transboundary effects must be considered. This will include interaction between the human environments either side of the boundary and the potential for impacts to protected sites or species within UK waters to transfer into protected sites in Norwegian waters. The scale and consequence of any trans-boundary effects will be comparable, or less, than those in UK waters. In the event of an oil spill entering Norwegian waters it may be necessary to implement the NORBRIT Agreement (the Norway-UK Joint Contingency Plan), which sets out command and control procedures for pollution incidents likely to affect both parties.

11.2 OTHER SEABED USERS

In general, there are two main cumulative impacts to be considered when assessing the effects of a project on the surrounding region. These are:

Whether the combined footprints of overlapping projects have the potential to exacerbate the environmental impacts from the respective projects.

Whether projects that do not overlap, when considered in combination, will result in the loss or disturbance of substantial areas of a particular regional habitat.

11.2.1 Commercial fishing

The Alma region is of moderate importance for demersal fisheries and low importance for pelagic or shellfish species (Coull et al., 1998). As discussed in Section 10.1, the development is within an area which contributes 48% to the average annual values for herring caught in the region. There are potentially two types of cumulative impacts associated with fisheries: physical disturbance of the seabed and effects on marine ecology. The ES has demonstrated that, given the highly dynamic environment within the project area, physical disturbance, as a result of construction activities, is unlikely to be noticeable above background levels within a minimum of 5 years of the these activities ceasing (Sections 8.4, 9.3 and 10.1). In addition, the community type in the project area is typical for the region and it is considered that the combination of disturbance from trawling and construction will not cause an overall significant loss of habitat type or change in community structure.

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11.2.2 Offshore wind farms

Offshore wind farms are becoming more prevalent in UK waters, of which the “Zone 3 - Dogger Bank” (Round 3) is the closest, located 53km to the south of the proposed Alma field development. The zone has been awarded to the developer Forewind7 (Crown Estate 2011). The first phase is expected to be ready for construction in late 2014. The site is anticipated to have an overall production capacity of 13GW of energy. Due to the distance of the wind farm from the Alma development, it is unlikely that there will be any in combination effects from habitat removal, sediment disturbance and noise generation from piling during construction, especially as the wind farm will not start construction until after completion of construction at the Alma development.

11.2.3 Marine aggregate extraction areas

The closest marine aggregate dredging site is the Area 466/1 application area, licensed to Cemex UK Marine Ltd, situated 139km south west of the southern drill centre. Impacts on the marine environment from aggregate extraction primarily relate to the direct disturbance of the seabed and the corresponding effects on marine ecology. Impacts are generally restricted to the area of seabed licensed; although, depending on the dredging activity and prevalent hydrodynamic conditions, sediment plumes from aggregate screening may impact benthic communities within a radius of a few kilometres from the license zone. Due to the distance from aggregate extraction sites, in-combination effects with the Alma development are unlikely. In addition, marine aggregate extraction generally targets sublittoral sands and gravels which support a reasonably diverse biological community, in contrast to the essentially sparse biodiversity of the community found on the fine sands in the Alma project area (see Section 9.2). Therefore, regional impacts from the combined disturbance/loss of habitat types are not anticipated.

11.3 CLIMATE CHANGE

As discussed in Section 8.2, CO2 emissions from the Alma development will contribute, albeit negligibly, to climate change. However, it is also possible that impacts from the development may act in combination with impacts related to climate change to exacerbate physical and biological changes in the environment. Alma has an expected production life of 10 years. Climate change is likely to change the physical and biological baseline environment in the project area over the next 10-25 years. The following impacts on the project area are expected as a consequence of climate change:

Sea level rise – This is expected to slightly affect tidal currents, wave propagation and mobility of seabed sediments (HR Wallingford 2007). However, any changes are likely to be incremental within the project area and within the ranges of survey error. The predicted sea level rise will not affect tidal current direction of strength (HR Wallingford 2007).

Ocean acidity and temperature – Minor changes are expected to occur over the next 10-25 years, with major biological shifts potentially occurring

7 Forewind Consortium – comprising four partners ; SSE (Scottish and Southern Energy plc); RWE npower renewables, the UK subsidiary of RWE Innogy, and two of Norway’s largest companies, Statkraft and Statoil (Crown Estate 2011)

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in the longer term i.e., 100 years. Although, it is unknown how the region’s biological communities will be affected, there is the potential that there will be rapid alterations in the nature and structure of benthic and water column communities. There may also be a northward migration of species as temperature increases. Increased levels of CO2 in the sea lead to more acidic waters which are likely to reduce the resilience of marine ecosystems, particularly affecting species composed of calcium carbonate. The EIA identified the Alma development will not have any residual impacts on water depth, wind speed or wave conditions. Residual impacts on the environment will be short-term, predominantly affecting marine ecology. As climate change has the potential to affect the biological baseline it is possible that the project can act in combination with climate change to exacerbate this impact. However, the EIA concludes that, following construction, biological communities are anticipated to recover to pre-impact levels/structures or similar within five years (see Section 9.2.4.1). Given the relatively short timescale of the construction impacts, it is considered unlikely that any cumulative impacts from the project and climate change will have significant impacts on marine ecology.

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12 ENVIRONMENTAL MANAGEMENT

This section provides an overview of the management systems in place at EnQuest. Whilst the emphasis of an Environmental Statement (ES) is on environmental management, it overlaps with aspects of health and safety and quality management. The following sections therefore describe the management tools EnQuest have in place which cover health, safety, environment and quality (HSEQ). The section also describes how the mitigation measures proposed in this ES will be adopted and bridged into the wider context of the EnQuest Health, Safety and Environmental Management and Quality systems.

12.1 MANAGEMENT SYSTEM

EnQuest is a socially responsible employer, committed to maintaining high standards in health, safety and environmental performance. EnQuest implements and operates an integrated Health, Safety and Environmental Management System (HS&EMS) and a Quality Management System (QMS) which has been accepted and endorsed by the Board, and embedded in the overall business culture. The HS&EMS is an integral part of the overall management system. It is laid down in policies, procedures, standards and work instructions. Its general purpose is to prevent EnQuest’s activities from putting people, the environment, property or the reputation of the company at risk. The HS&EMS is designed to match the requirements of ISO-14001:2004 and is based on the requirements of the Health and Safety OHSAS 18001 standard. The QMS is certified to BS EN ISO 9001. The purpose of the HS&EMS and QMS is to enhance health, safety, environmental and quality (HSEQ) performance and provide a framework for HSEQ management for all of the activities carried out throughout the company. The management systems are designed to cover HSEQ aspects which EnQuest can control and directly manage and those it does not control or directly manage, but can be expected to influence. EnQuest requires all contractors, their subcontractors and suppliers to have their own HS&EMS and QMS. Each contractor will be responsible for the HS&E management of their scope of work and will operate according to their own HS&E Management System. However, contractors HS&EMS must be compatible with EnQuest’s HS&EMS and they are required to align their HS&E management with EnQuest’s goals and objectives. Their QMS must meet the applicable requirements of the BS EN ISO 9000 series of standards or an agreed equivalent.

12.2 PROJECT SPECIFIC ENVIRONMENTAL MANAGEMENT

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the project as a whole and will implement and maintain a number of documents and processes which include:

Project HSE and Quality Plans

Regulatory Compliance Procedure

Risk management system

Document management control However, everyone working on the project either directly or indirectly has a responsibility for ensuring that they meet defined HS&E requirements for their own particular activities. The Alma development HS&E plan (EnQuest 2011) describes how EnQuest will manage HS&E activities arising from the Alma Field Development. This Plan applies from the concept selection stage through to the project execution phases of the project and:

Describes how EnQuest will manage the HS&E aspects arising from the project

Presents the key HS&E requirements of the project

Clearly defines HS&E roles and responsibilities

Provides a vehicle for tracking and monitoring

Provides an auditable trail for Project HS&E management

Sets out EnQuest’s environmental targets as shown in Table 12-1 Table 12-1: EnQuest environmental targets Objective Target Comment All permits in place and permit conditions Compliance with consent identified to contractors. Exception Reporting requirements No deviations from permit requirements No breaches of waste regulations Compliant management of waste Waste categorisation and monitoring sufficient Exception Reporting for EEMS reporting Assurance that the Rig and Confirmation of appropriate and effective Verify through Audit Installation Vessels are fit for rig/vessel audit regime. Report purpose No incidents or spills Well testing is efficient with respect to atmospheric Assurance that UKOOA Guidelines followed Exception reporting emissions Improvement opportunities for Specific improvement opportunities identified Lessons learned future project activities identified and recorded at close out. Register Source: Extracted from EnQuest HSEQ policy 2011 All contractors will be requested to develop their own HS&E Plans, which are aligned to the EnQuest Project HSE Plan and are in line with EnQuest project goals and objectives. Compliance with relevant HS&E regulations, codes and standards also needs to be common across all of the companies that will participate in the development.

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Competency of contractor personnel and contractor’s means of achieving a competent workforce for EnQuest projects will be identified in the HSE Plan, assessed in contractor selection and monitored during contractor duration. During construction bridging documents will be in place between the contractors and EnQuest. These will describe the management structure and division of responsibilities, the methodology of execution of the work programme and any emergency response procedures. EnQuest actively monitor and audit contractor’s operational control procedures and their implementation. For example, contractor’s proposed method statements, programmes and resources are reviewed during contractor selection (procurement) and all plans, procedures and standards for operational control are reviewed and approved by EnQuest. The project will be subject to statutory regulatory control which requires various applications and notifications to be made to nominated governmental bodies for approval of the relevant activities. Effective management of these activities is critical for the success of the project and to enable this EnQuest will establish a Permits Licenses Approvals Notifications and Consents (PLANC) register. The register will be regularly monitored to ensure that the necessary consents or notifications are in place when required during the development. The HSEQ Engineer will develop and manage the PLANC register. The following are the key permits and consents requirements:

Environmental Statement (ES) approval

Field Development Plan (FDP) approval

Pipelines Works Authorisation (PWA)

Petroleum Operations Notices (PON) approval e.g., PON15C (pipelines), PON15B (drilling), PON15D (FPSO)

Oil Pollution Emergency Plan (OPEP) It is expected that the mitigation measures identified in the EIA process and reported in this ES will be adopted and bridged into EnQuest’s HSEQ Management System through the PLANC register.

12.3 MANAGEMENT OF MITIGATION MEASURES

It is anticipated that the mitigation measures identified in the EIA process and reported in this ES will be adopted and bridged by EnQuest’s HSEQ Management System through the PLANC register. In addition to the standard best practice mitigation measures, including those that are regulatory requirements, which will be enforced during construction and production (see summary in Table 12-2 and Appendix A) EnQuest are committed to the following:

1) Production flaring will be kept to a minimum 2) JNCC guidelines on disturbance will be followed to prevent committing an offence under the Conservation (Natural Habitats &c) Regulations 1994 (as amended in 2010) (HR) and the Offshore Marine Conservation (Natural Habitats &c) Regulations 2007 (as amended in 2010) (OMR).

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Table 12-2: Summary of mitigation measures Mitigation measures Ensure all machinery is maintained and serviced Use of cleaner low emission fuels. Stack heights in accordance with the relevant regulations. Ensure all machinery used for transfers is regularly cleaned and maintained. Every vessel will have and implement a written waste management plan, compliant with MARPOL 73/78. Annex V (Garbage) is particularly relevant. No plastics/plastic containing material will be disposed of at sea, regardless of location. Paper & food wastes will only be discharged outside the 12nm limit. General household products will be selected that are environmentally benign. Daily recording of chemical use to allow more refined and efficient use. Where possible chemicals will be recycled, skipped and shipped or re-injected and not discharged. Selections of chemicals will be made in accordance with the CEFAS ranked list, where chemicals ranked as lower potential hazards are preferentially chosen. Only chemicals permitted through the relevant Offshore Chemicals Regulations chemical permit (i.e. PON15B, C or D) and that have been subject to a risk assessment will be discharged. All oil discharges will be covered by an approved OPPC permit. The footprint of any anchors, infrastructure and protective structures will be minimised A 500m safety exclusion zone will be in place around the FPSO and drilling rig at all times, enforced by designated guard vessel The FPSO, drilling rig and support vessels will be appropriately lit. The tanker and supply vessels will follow defined routes. All relevant notices will be placed in the Kingfisher Bulletin and “Notice to Mariners” All subsea structures have been designed to be fishing friendly Produced water discharge will be closely monitored to ensure that all contaminants are at an acceptable level. Oil in water, chemical, aromatic and radionuclide concentrations will all be reported via the appropriate OCR permit i.e., PON15D. Any produced water potentially contaminated with reservoir hydrocarbons will be recycled or re-injected and not discharged unless below permitted levels for discharge via an Oil Pollution, Prevention and Control (OPPC) permit. A location specific approved OPEP will be in place for the development that covers drilling and production The OPEPs will detail all emergency procedures that will be in place to minimise any spill. Control measures will be in place to ensure rapid response to loss of pipeline containment. These will be outlined in the Alma OPEP. Accidental spills will be kept to a minimum through training, good housekeeping and through storage/handling procedures e.g., sumps, drains and bundling should catch accidental spills. Management controls will be in place to eliminate bunkering spills e.g. only bunkering during day light and in good weather. EnQuest has access to Tier 1, 2 and 3 oil spill response capabilities through Oil Spill Response Limited (OSRL). EnQuest is a member of OSPRAG which will provide support in a well blow out event. Every reasonable measure will be taken to retrieve dropped objects. If the object cannot be retrieved a PON2 will be submitted to the DECC. A dropped objects plan will be developed to address risk of dropping objects during construction and operations.

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12.4 OIL SPILL RESPONSE

The Alma field will have a site specific oil pollution emergency plan (OPEP) that meets the requirements of The Merchant Shipping (Oil Pollution Preparedness, Response Co-operation Convention) Regulations, The Offshore Installations (Emergency Pollution Control) Regulations and the latest guidance issued by the DECC. The OPEP will cover onshore and offshore responses for an incident in the Alma field. It will take into consideration drilling activities at the drill centres’, production activities on the FPSO, the production of crude oil and chemicals in the flowlines and the export of crude oil in the offloading tankers. EnQuest has subscribed to Oil Spill Response (OSR) to provide clean-up expertise and equipment in the event of oil spills. In addition, EnQuest has a contract with Petrofac to provide 24 hour emergency support, including the use of the Petrofac Emergency Response Centre (ERC). Equipped with a competent team of professionals, the ERC will be used to coordinate onshore response if required. EnQuest operates a three-tier response system.

Tier Three consists of the Incident Management Team (IMT), with at least one member on call 24 hours a day, seven days a week. The IMT Duty Manager is the first responder to the ERC.

Tier Two is the first level of the EnQuest Crisis Management Team (CMT). Mobilised by the IMT Duty Manager, the CMT sits at EnQuest’s Aberdeen office. Should an incident escalate, requiring more corporate support,

Tier One is activated, which consists of EnQuest’s senior leadership team, based EnQuest’s company headquarters in London. The installed wellheads will have H4 connectors that will be compatible with the capping device being built under the Well Life-Cycle Decision Framework (WLCDF) Oil and Gas UK (OGUK) initiative.

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13 CONCLUSIONS

13.1 THE PROJECT

The field, to be renamed Alma, will be a re-development of the existing Ardmore field, located within the CNS. Alma will be developed through two drill centres tied-back via new oil production and water injection flowlines to the Uisge Gorm FPSO. The development will consist of six production wells and two water injection wells (which will be used to drive production due to low reservoir pressures). The field is located in UKCS Blocks 30/24 and 30/25, which is 274km east of the nearest landfall on the Northumberland coastline and 18.5km from the UK/Norway median line. Construction is expected to commence in January 2012, with the rig remaining on site until April 2013. Field life is anticipated to be ten years. Overall, the proposed development is regarded as being a small scale oil development, in the context of other oil and gas developments in the wider CNS. Construction activities will generate a range of routine emissions/discharges to air and sea respectively, e.g.;

Atmospheric emissions

Drill cuttings and water based mud discharges

Chemical discharges

Waste water and sewage discharges

Subsea noise Once producing, the development will emit produced water containing small quantities of oil and atmospheric emissions.

13.2 EXISTING ENVIRONMENT

Existing conditions at the Alma development were established through an environmental baseline and habitat assessment survey, which revealed that:

No habitats or species of conservation significance under the UK’s Offshore Marine Conservation (Natural Habitats, &c.) (Amendment) Regulations 2010 were observed during seabed surveys. The environmental baseline is similar to other regions of the CNS where oil and gas activity is prevalent. Meteorological conditions around the project support a dilution and dispersion regime which will rapidly reduce the impact significance of emissions to air, water and seabed (i.e., winds are sufficient to disperse atmospheric emissions, tidal currents refresh the water column within an estimated 1.5 hours, currents are generally sufficient to disperse drill cuttings or sediment piles on the seabed within a minimum of 5 years).

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13.3 POTENTIAL IMPACTS

The potential effects of the project on the environment were identified and quantified by reviewing the existing baseline environmental conditions with the potential to be affected by the project and identifying and evaluating the effect of any activities associated with the project on these conditions. It should be noted that the majority of activities were assessed as having negligible or minor residual impact on the receiving environment, with a few identified as having a residual impact of moderate significance. This ES reached the following conclusions with regards to the project’s impacts on the environment:

Benthic Environment: The total seabed footprint of the development is 0.04km2. Due to fishing activities and previous oil and gas industry activities, the benthos in the project area is typical of a moderately disturbed habitat and consequently species that inhabit the area tend to recover quickly after disturbance. The development area is sufficiently homogenous that any localised losses are unlikely to affect the integrity of the community as a whole. The placement of protective structures such as concrete mattresses will create new habitat for those species that require hard substrate for anchoring. This could lead to settlement of new species and the potential for a localised change in marine ecology. Current speeds are sufficient to erode cuttings piles and these are unlikely to persist for a long period of time. Seabed activities that cause physical disturbance have been classed as having a moderate to minor residual impact.

Protected Species: No protected species were identified in the marine benthic surveys. Marine mammals are likely to be the only protected species of relevance in the Alma development. A small amount of piling will be necessary during construction activities which will create subsea noise. A noise assessment was carried out, following the current JNCC guidelines which identified that, provided mitigation measures are followed, the sound experienced will not exceed the injury or non-trivial disturbance thresholds for marine mammals. There is therefore a negligible risk of an offence under the Conservation (Natural Habitats &c) Regulations 1994 (as amended) and the Offshore Marine Conservation (Natural Habitats &c) Regulation 2007 (as amended in 2010).

Protected Are as: There are no protected sites within 40km of the Alma development. The nearest protected site is the Dogger Bank potential Special Area of Conservation (pSAC) which is approximately 78km south- east from the Alma southern drill centre. Due to the distance of the protected site from the development area, it is unlikely that there will be any impacts during normal activities.

Water/Sediment Quality: No activities were identified during construction or production that would have the potential to have a significant residual impact on water or sediment quality.

Air Quality: Given the generally dynamic offshore, concentrations of NOx and SOx from construction and production activities are not expected to reach European Commission alert thresholds and there is expected to be a minor residual impact on regional air quality.

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Commercial Fishing and Other Marine Users: With consideration of other development activities in the CNS, safety exclusion zones are likely to have a minor impact on commercial fishing in the area as this will result in vessels being displaced from their fishing grounds. Snagging hazards will be mitigated for by using standard best practice and industry measures (i.e. use of fishing friendly structures).

Accidental Events: Spill of hydrocarbons: In the unlikely event of a major oil spill, a worst case scenario loss of containment of 100,000m3 (87,000 tonnes) of crude oil from the export tanker has been modelled. This indicates that depending on the prevailing wind conditions there is a 1% chance of beaching occurring on a coastline of a North Sea bordering country. Modelling also indicates that, without an intervention response, depending on the prevailing wind conditions, the spill could reach the UK coastline within 8 days and 10 hours and the Danish coastline within 5 days and 12 hours. The spill is likely to have completed dispersed within 417 days. There are numerous protected areas along the coastlines of North Sea bordering countries that could be affected by a spill (Figure 8-3). EnQuest will have an OPEP in place to manage spill response.

Cumulative and transboundary impacts: The potential for cumulative impacts stems from both current on-going production operations and new developments. The Alma Field is in an area of extensive oil development where activities have left their mark on the seabed. Alma is a relatively small development and it is unlikely that the incremental change to seabed disturbance, produced water and atmospheric emissions is likely to substantially change the physical and biological characteristics of the region.

13.4 DECOMMISSIONING

Field life is estimated to be approximately ten years and therefore decommissioning and abandonment will occur around 2023. The arrangements for decommissioning the wells and pipelines will be developed in accordance with UK government legislation and international agreements in force at the end of field life. The potential impacts from decommissioning have not been considered in this EIA. They will be the subject of a separate EIA submitted prior to decommissioning.

13.5 ENVIRONMENTAL MANAGEMENT

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14 REFERENCES

Anatec (2011). Consent to Locate - Alma (Technical Note). Prepared by Anatec on behalf of EnQuest 2nd June 2011. Reference: A2668-ENQ-CR-1 BGS (2004). Technical Report produced for Strategic Environmental Assessment – SEA2: North Sea Geology. TR_008 BSI (2001). Environmental Management - Environmental assessment of sites and organisations (EASO), Reference Number: ISO 14015: 2001 (E). Communities and Local Government (2010). Planning Policy Statement 25: Development and Flood Risk. HMSO, London. Compass Hydrographic Surveys Ltd (2004). Marine Aggregate Licence Area 430: East of Southwold Conoco Phillips (2011). http://w3.conocophillips.com/gcommon/internet/html/reports/sdreport/minimize3 _water.html Coull, K.A., Johnstone, R., and Rogers, S.I. (1998). Fisheries Sensitivity Maps for British Waters. Published and distributed by UKOOA DECC (2009a). Guidance notes for Industry. Guidance notes on the Petroleum Production and Pipelines (Assessment of Environmental Effects) Regulations 1999 (as amended). Version No:-46. Issued 10/08/2009. DECC (2009b). UK Offshore Energy Strategic Environmental Assessment. Environmental Report, January 2009. DECC (2011a). Promote UK 2011. Prospectivity of the United Kingdom (UK) Continental Shelf: North Sea Opportunities. https://www.og.decc.gov.uk/UKpromote/summary_information/North_Sea_intro _2011.pdf [Accessed February 2011]" DECC (2011b). Water Production sorted by field. [Accessed March 2011] DECC Online Maritime Data GIS system. Available from http://www.maritimedata.co.uk/. [accessed June 2011] Defra (2011). http://www.defra.gov.uk/news/2011/03/18/marine-policy- statement/ Dore, C.J., Murrells, T.P., Passant, N.R., Hobson, M.M., Thistlethwaite, G., Wagner, A., Li, Y., Bush, T., King, K.R., Norris, J., Coleman, P.J., Walker, C., Stewart, R.A., Tsagatakis, I., Conolly, C., Brophy, N.C.J. and Hann, M.R. (2008). UK Emissions of Air Pollutants 1970 to 2006. Issue 1. AEA Technology plc prepared for Defra. DTI (2001a). Strategic Environmental Assessment of the Mature Areas of the North Sea (SEA2). Consultation Document, H.M.S.O, London. DTI (2001b). Contaminant Status of the North Sea. Strategic Environmental Assessment - SEA2 Technical Report 004

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DTI (2001c). North Sea Fish and Fisheries: Technical report produced for Strategic Environmental Assessment – SEA2. Produced by Cefas & FRS DTI (2001d). Background Information on Marine Mammals Relevant to SEA2. Technical Report 006 produced for Strategic Environmental Assessment – SEA2. Produced by Sea Mammal Research Unit (SMRU), August 2001. DTI (2001e). Human Activities in the North Sea Relevant to SEA2: Technical Report 007 - Existing activities. Produced by BMT Cordah DTI (2002). Background information on marine mammals relevant to SEA 2 and 3. Technical Report 006 to inform SEA 2 and 3. Prepared by Hammond, P.S., Gordon, J.C.D., Grellier, K., Hall, A.J., Northridge, S.P., Thompson, D., and Harwood, J. Available online http://www.offshore- sea.org.uk/consultations/SEA_3/TR_SEA3_Mammals.pdf [Accessed December 2008] DTI (2007). Meeting the Energy Challenge - A White Paper on Energy. May 2007 EnQuest (2010). Ardmore Redevelopment Basis of Design. Document No. KNI- PM-000-BOD-0002 Revision A1 EnQuest (2011). Ardmore Redevelopment Project HSE Plan. Document No. ENQ-KNI-HS-000-PLA-0001 European Commission (1999). Guidelines for the Assessment of Indirect and Cumulative Impacts as well as Impact Interactions. EC DG XI Environment, Nuclear Safety & Civil Protection. May 1999. Produced by Hyder. Flemming, N.C. (2002). The scope of Strategic Environmental Assessment of North Sea areas SEA3 and SEA2 in regard to prehistoric archaeological remains. August 202 Report prepared for the DTI SEA3_TR014 Gaz de France Britain (2005). Cygnus Exploration Well Environmental Statement. DECC Project Reference No.: W/2880/2005. GEL (2011). Alma Field Development Site Survey: Environmental Baseline & Habitat Assessment Survey. Ref 8602 GGL (2011). UKCS Blocks 30/24, 30/25, 30/29 and 30/30 Alma Field Development December 2010 to January 2011 Survey report HM Government (2009). The UK Low Carbon Transition Policy. National strategy for climate and energy. 15th July 2009. JNCC (2010). The protection of marine European Protected Species from injury and disturbance. Guidance for the marine area in England and Wales and the UK offshore marine area. Prepared by JNCC (June 2010). JNCC (2011). http://www.jncc.gov.uk/page-4535#DoggerBank accessed 08/02/2011 Johnston, C.M., Turnbull, C.G. and Tasker, M.L. (2004). Natura in UK Offshore waters: Advice to support the implementation of the EC Habitats and Birds Directive in UK Offshore waters. JNCC 04 P23. KISCA (2010). GIS data, last downloaded February 2010

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Law, R.J., Waldock, M.J., Allchin, C.R., Laslett, R.E. and Bailey, K.J. (1994). Contaminants in seawater around England and Wales: Results from monitoring surveys, 1990-1992. Mar. Pollut. Bull., 28: 668-675 MMO (2010). 2004 – 2009 landings data for ICES rectangles 41F2 MCA (2011). http://www.dft.gov.uk/mca/ Met Office (2011). Met Office European model (56.0°N 3.14°E Jan 1998 - Nov 2008) OGUK (2006). Good practice for cleanup in well operations. Revision 1. Oil and Gas UK Environmental Legislation website: Well Clean-up. OGUK (2008). Environmental Legislation Website. The Statutory Regime. Web page updated 29 October 2008. [Accessed November 2008] OGUK (2009). EEMS Atmospheric Reporting Data 1.0 - Facility Emissions (Reporting Year 2008) OGUK (2010). EEMS Atmospheric Reporting Data 1.0 - Facility Emissions (Reporting Year 2009) Olsgard, F. and Gray, J.S., (1995). A comprehensive analysis of the effects of offshore oil and gas exploration and production on the benthic communities of the Norwegian continental shelf. Marine Ecology Progress Series, 122: 277- 306. OSPAR Commission (2000). Quality Status Report 2000, Region II – Greater North Sea. OSPAR Commission, London. 136 + xiii pp Available online http://www.ospar.org/content/content.asp?menu=00790830300000_000000_00 0000 [Accessed January 2009] OSPAR Commission (2010). Quality Status Report 2010 for the North-East OSR (2011). Oil Spill Modelling for Alma Field Development. Prepared for Metoc Ltd. Project Number 4558. Reid, J.B., Evans, P.G.H. and Northridge, S.P. (2003). Atlas of Cetacean distribution in northwest European waters. Joint Nature Conservation Committee, Peterborough, UK. Richardson, W.J., Thomson, D.H., Green Jr, C.R. and Malme, C.I. (1995). Marine mammals and noise. Academic Press, New York. RYA (2008). UK Coastal Atlas of Recreational Boating. Recreational Cruising Routes, Sailing and Racing Areas around the UK Coast. Second Edition Sadler, B. and McCabe, M (Eds) (2002). United Nations Environmental Programme (UNEP) EIA Training Resources Manual, Second Edition. http://eia.unu.edu SCANS-II (2008). Small Cetaceans in the European Atlantic and North Sea. Final Report submitted to the European Commission under project LIFE04NAT/GB/000245. Available from SMRU, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife, KY16 8LB, UK.

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Skov, H., Durinck, J., Leopold, M.F., and Tasker, M.L. (1995). Important Bird Areas for seabirds in the North Sea. BirdLife International, Cambridge Stone, C.J., Webb, A., Barton, C., Ratcliff, N., Reed, T.C., Tasker, M., Camphuysen, C. J. and Pienkowski, M.W. (1995). An atlas of seabird distribution in the north-west European waters. Joint Nature Conservation Committee, Peterborough. Stone, C.J. (2003). The effects of seismic activity on marine mammals in UK waters, 1998-2000. JNCC Report No. 323. Joint Nature Conservation Committee, Peterborough, UK. The Crown Estate (2011). The Crown Estate UK Climate Impact Programme (2002). UKCIP02 Climate Change scenarios gateway. UK Deal (2010). GIS data, last downloaded November 2010 UK National Air Quality Archive (2009). http://laqm.defra.gov.uk/maps/maps2008.html UK National Air Quality Archive (2011). http://uk-air.defra.gov.uk/ UKCP (2009). UK climate change predictions http://ukclimateprojections.defra.gov.uk/content/view/2013/500/ UKMMAS (2010). Charting Progress 2 - The State of UK Seas. http://chartingprogress.defra.gov.uk/ UKOOA (1999). Drill Cuttings Initiative, Research and Development Programme. Activity 2.1. Faunal Colonisation of Drill Cuttings Pile Based on Literature Review. United Kingdom Offshore Operators Association, Aberdeen, UK. UNFCCC (2008). United Nations Framework Convention on Climate Change (1994). http://unfccc.int/essential_background/convention/items/2627.php Wills, J. (2000). A Survey of Offshore Oilfield Drilling Wastes and Disposal Techniques to Reduce the Ecological Impact of Sea Dumping. Prepared for Ekologicheskaya Vahkta Sakhalina (Sakhalin Environment Watch). http://www.offshore-environment.com/drillingwastecontents.html [accessed October 2008]

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Appendix A Environmental Impact Assessment

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A.1 Interaction Matrix

Environmental Receptor Physical Biological Human Plankton Seabirds Shipping Shipping Air quality Air quality and species and species Archaeology Archaeology Climate change change Climate Water resources Water resources Marine mammals Marine mammals Fish and shellfish Seabed conditions Other marine users users marine Other Commercial fisheries fisheries Commercial Benthic communities Project Activity Marine protected sites General Construction Physical presence and movement of vessels Bulk storage and transfer Drilling of wells Installation of flowlines Installation of FPSO Production Physical presence, operation and maintenance of FPSO Physical presence and movement of export tanker and supply vessels Flaring during initial stages of production Presence of subsea infrastructure Accidental Events Overboard loss of equipment or waste Chemical / hydrocarbon release (< 1 tonne) Chemical / hydrocarbon release (1-10 tonnes) Chemical / hydrocarbon release (> 10 tonnes)

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A.2 Construction

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Mitigation Measures Severity Factors Activity Impact

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

A – Air Quality

A-1 Physical Exhaust gas Localised y Ensure all machinery is maintained. Atmospheric emissions from exhaust gases will be low (Section 6.1.1). presence and emissions deterioration in Use of cleaner low emission fuels. Pollutants will be dispersed and diluted to levels below health and ible ible nificant nificant movement of air quality g environmental guidelines within 500m of the discharge point. See Section Unlikel li g y vessels g Stack heights in accordance with the 8.1.5 for full discussion. Insi Ver N ------9.1 Ne relevant regulations.

A-2 Bulk storage Dust release Localised y Ensure all machinery used for transfers Dust released from the bulk transfer/storage of chemicals and/or cements and transfer during transfer deterioration in is regularly cleaned and maintained. will be low (Section 6.1). Any dust released into the atmosphere will disperse ible ible nificant nificant air quality g and settle on the sea surface around the rig where it will quickly disperse Unlikel li

g y g through the water column. As the amount of dust released will be minimal, Insi N ------8.1 Ver Ne no residual impact on air quality is envisaged. B - Climate Change

B-1 Physical Exhaust gas Loading of As per Section A-1 Approximately 47,585 tonnes of CO2 will be emitted during construction presence and emissions greenhouse (Section 6.1.1). As a comparison the annual emissions represent 0.97% of

y ible ible nificant nificant movement of gases e.g., g UK emissions from similar offshore activities in 2009. This is a relatively li g vessels CO2, CH4, g small contributor to annual UK emissions and is typical for a standard oil Insi Ne N ------8.2 Unlikel development of this size. See Section 8.2.5 for full discussion. C - Water Resource C-1 Physical Discharge of Localised Every vessel will have and implement a It is estimated that a maximum of 17,359m3 of sewage and grey water will presence and sewage, grey deterioration in written waste management plan, be discharged to sea from construction vessels (Section 6.1.2.2). Given the movement of water, food water quality compliant with MARPOL 73/78. prevalent metocean conditions in the project area (e.g., winds, waves, tides vessels waste and Annex V (Garbage) is particularly and currents), the short-time scale of the construction period and the small drainage relevant. No plastics/plastic containing cumulative volume of discharges, the marine environment will be able to water material will be disposed of at sea, rapidly assimilate the discharges through natural bacterial action. regardless of location. Paper & food Considering the active mitigation in place it is likely that any degradation in

water quality will be transient (limited to a few hours after the discharge) and

y wastes will only be discharged outside there will not be any residual impacts on water quality. ible ible the 12nm limit. r g Likel li y g General household products will be Mino N ------8.3 Ver Ne selected that are environmentally benign.

REPORT REF: P1459BA_RN2525_REV0 A-3 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

C-2 Bulk storage Dust release Localised Ensure all machinery used for transfers Dust released from the bulk transfer/storage of chemicals and/or cements and transfer during transfer deterioration in is regularly cleaned and maintained. will be small (Section 6.1). Any dust released into the atmosphere will water quality disperse and settle on the sea surface around the rig where it will quickly ible ible

r g disperse through the water column. Any degradation in water quality will be li g transient (limited to a few hours after the discharge) and it is unlikely that Mino Possible Ne there will be any residual impacts on water quality. N ------8.3 C-3 Drilling of wells Discharge of Localised Daily recording of chemical use to allow All discharges will be risk assessed and be within permitted levels. Currents -1 Installation of chemicals deterioration in more refined and efficient use. in the project area are of average strength for the CNS (0.2ms ) and flowlines (including water quality Where possible chemicals will be combined with wave action will disperse and dilute chemical discharges WBM) during construction. Currents will refresh a 500m radius column of water recycled, skipped and shipped or re- injected and not discharged. surrounding the discharge location within one and a half hours (Section 8.3). No lasting effect on water quality is expected. Selections of chemicals will be made in accordance with the CEFAS ranked list, where chemicals ranked as lower potential hazards are preferentially chosen. Only chemicals permitted through the relevant Offshore Chemicals

y Regulations chemical permit (i.e. ible ible

r g PON15B or PON15C) and that have Likel li y g been subject to a risk assessment will be Mino N ------8.3 Ver Ne discharged. C-4 Drilling of wells Discharge of Localised All discharges will be covered by an All discharges will be within permitted levels and visibly oily contaminated reservoir deterioration in approved OPPC permit. fluids will not be discharged. Currents in the project area are of average -1 hydrocarbons water quality Visibly oily contaminated fluids will not be strength for the CNS (0.2ms ) and combined with wave action will disperse ible ible

r g reservoir hydrocarbons during drilling. Currents will refresh a 500m radius

li discharged. g column of water surrounding the discharge location within one and a half Mino N ------8.3 Possible Ne hours (Section 8.3). No lasting effect on water quality is expected.

REPORT REF: P1459BA_RN2525_REV0 A-4 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

C-5 Installation of Concrete Increased No mitigation envisaged. A maximum of 9,180m2 of seabed will be covered by concrete mattresses flowlines mattressing suspended and contingency rock placement. As the material is placed on the seabed, and rock sediment loads sediments will be displaced and suspended. Sediment particle analysis placement & turbidity indicates that sediments are predominantly sand, which will quickly fall out of suspension due to its weight. The silt content is negligible and there is

y unlikely to be a significant increase in suspended sediment loads in the ible ible

r g water column. In addition, the impact occurs against a background of Likel li y g seabed disturbance as a result of wave and tidal activity. The impact will be Mino Ver N ------8.3 Ne localised and very short-term in terms of effects on water quality. C-6 Installation of Trenching Increased The impact will be minimised through As the water injection flowline is jet trenched into the seabed, sediments will flowlines and backfill suspended careful route design. be displaced and suspended. Sediment particle analysis indicates that sediment loads sediments are predominantly sand, which will quickly fall out of suspension. & turbidity The silt content is negligible and there is unlikely to be a significant increase

y in suspended sediment loads in the water column. In addition, the impact ible ible

r g occurs against a background of seabed disturbance as a result of wave and Likel li y g tidal activity. The impact will be localised and very short-term in terms of Mino N ------8.3 Ver Ne effects on water quality. C-7 Installation of Physical Increased No mitigation envisaged. As per Section C-6, if the flowlines and manifolds are placed on the seabed, flowlines presence of suspended sediments will be displaced and suspended. The impact will be localised ible ible subsea sediment loads and very short-term in terms of effects on water quality. r g li

infrastructure & turbidity g Mino N ------8.3 and flowlines Possible Ne D -Seabed conditions D-1 Physical Anchoring Disaggregation The footprint of the anchors will be A total of 8 anchors will be deployed within a 1,000m (3,281ft) radius of the presence and of surface minimised. rig at each drill site. The total area of seabed impacted by all anchors and movement of sediments chains has been estimated at 5,200m2. Anchor mounds are common vessels where seabed sediments or shallow sub-surface sediments are composed of clay and are expected to persist for ten years or more. The Alma development area comprises a <1m thickness of very loose to loose silty shelly sands (with a varying degree of gravel and shells) over firm to very stiff sandy gravelly clay. When retrieved, the anchors are expected ible ible to leave a small area of residual disturbance.

r g y li g However, the area impacted is minor when compared to the extent of the Mino Ne Y Likely Moderate Local Low Short Minor 8.4 Likel CNS and physical disturbance from other activities such as trawling.

REPORT REF: P1459BA_RN2525_REV0 A-5 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

D-2 Drilling of wells Discharge of Change in No mitigation envisaged Cuttings will be incorporated in the sediment through bioturbation and cuttings seabed general sediment mobility. Significant erosion of cuttings piles starts when ible ible -1

r topography g the seabed critical velocity reaches 0.35ms (UKOOA 1999). Seabed y li g currents (0.42ms-1) will ensure that all cuttings piles will disperse, although Mino Ne Minor Minor 8.4 Likel there is the possibility that they may persist for a number of years. Y Likely Moderate Local Low Short D-3 Drilling of wells Discharge of Sediment As per Section C-3 All discharges will be risk assessed and will be within permitted levels. Only Installation of chemicals contamination chemicals discharged at the seabed will have a direct impact on sediments. flowlines (including No discharge of OBM is permitted so levels of contamination are not WBM) expected to rise over existing historical levels. Barite and bentonite present in the WBM can contaminate sediments and be noticeable in sampling for up to 10 years after discharge. However due to the historical use of the area for oil and gas development it is unlikely that this will be a noticeable increase.

-1 y Currents in the project area are of average strength for the CNS (0.2ms ) ible ible and combined with wave action will disperse and dilute chemical discharges r g Likel li y

g during construction. Currents will refresh a 500m radius column of water Mino Y Very Likely Moderate Local Low Short Minor 8.4 Ver Ne surrounding the discharge location within one and a half hours (Section 8.3). D-4 Drilling of wells Discharge of Sediment As per Section C-4 Given the previous use of the area for oil and gas development, levels of ible ible

reservoir contamination r hydrocarbon contamination are not expected to rise over existing historical g li

hydrocarbons g levels. Mino Y Possible Moderate Local Low Short Minor 8.4 Possible Possible Ne

D-5 Installation of Physical Compaction The footprint of any structure will be The manifold will have a footprint on the seabed of 60m2. All surface flowlines presence of and minimised. sediment within this footprint will be unavailable for future colonisation. subsea disaggregation However, sediments in the surrounding area are not particularly sensitive. In infrastructure of surface addition, the area impacted is minor when compared to the extent of the and flowlines sediments CNS and physical disturbance from other activities such as trawling. As the water injection flowline is to be trenched directly into the seabed, this area of seabed will be disturbed but will then be available for colonisation purposes. The area of seabed directly underneath the production flowlines will not be available for colonisation purposes, however the flowlines (and

y protective structures) themselves offer a hard surface for colonisation. ible ible

r g Sediments in the area are not particularly sensitive and the impact will be Likel li y g localised. There will be no change in sediment composition and no Mino Y Very Likely Moderate Local Low Short Minor 8.4 Ver Ne contamination, therefore no long-term effects on sediments is envisaged.

REPORT REF: P1459BA_RN2525_REV0 A-6 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

D-6 Installation of Trenching Change in The impact will be minimised through The water injection flowline trench will have a seabed footprint of 15,000m2. flowlines and backfill surface careful route design. Sediments in the surrounding area are not particularly sensitive; however sediments use of the jet trenching system will bring sediments from deeper lithologies Change in to the surface. Whilst this will disturb the sediments, there will not be a topography significant change. As the jet trenching methodology does not create berms leading to or spoil piles, there is unlikely to be an affect on sediment transport changes in pathways. In addition, the area impacted is minor when compared to the ible ible extent of the CNS and physical disturbance from other activities such as r sediment g li transport g trawling. Mino Y Possible Moderate Local Low Short Minor 8.4 pathways Possible Ne D-7 Installation of Concrete Change in The footprint of any protective structures When the concrete mattresses and/or rock material are placed on the ible ible

flowlines mattressing seabed r will be minimised seabed, they will have a maximum footprint of 9,180m . A slightly raised g

li and rock topography g profile may mean that deposition or scour occur around mattresses and rock Mino Y Possible Moderate Local Low Short Minor 8.4 placement Possible Ne materials. D-8 Installation of Anchoring Compaction The footprint of the anchors will be The FPSO will have a footprint on the seabed of approximately 9m2 (1m2 FPSO and minimised per piled anchor). disaggregation The Alma development area comprises a <1m thickness of very loose to of surface loose silty shelly sands (with a varying degree of gravel and shells) over firm sediments to very stiff sandy gravelly clay. However, the area impacted is minor when compared to the extent of the

y CNS and physical disturbance from other activities such as trawling. ible ible

r g As the anchors for the FPSO will be pile driven into the seabed there will not Likel li y g be any anchor mounds created through re-anchoring. There will be no Mino Y Very Likely Short Local Low Short Minor 8.4 Ver Ne change to the sediment type or contamination of the seabed sediments. E - Plankton E-1 Physical Discharge of Organic As per Section C1 Cumulative discharge volumes will be very small and combined with the fact presence and sewage, grey enrichment that drilling rigs will not be on permanent location it is unlikely that any movement of water, food leading to discharges will lead to any measurable organic enrichment. vessels waste and raised biological

drainage oxygen y ible ible

r water demand. May g Likel li y change balance g Mino N ------9.1 Ver of food chain. Ne

REPORT REF: P1459BA_RN2525_REV0 A-7 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

E-2 Drilling of wells Discharge of Potential toxic As per Section C3 All discharges will be risk assessed and be within permitted levels. Installation of chemicals effects Although sensitive to changes in water quality, the plankton community flowlines (including undergoes a continual change in individuals with those from the surrounding

WBM)

y waters and therefore has extremely rapid recovery rates. ible ible

r g As per section C-3, discharged chemicals will not be present within the Likel li y g water column for long enough or at high enough concentrations to pose a Mino Ver N ------9.1 Ne significant threat to plankton. E-3 Drilling of wells Discharge of Potential toxic As per Section C-4 As per Section C-4. No lasting effect on plankton is expected. ible ible

r reservoir effects g li hydrocarbons g Mino N ------9.1 Possible Ne

F - Benthic communities F-1 Physical Anchoring Physical The footprint of the anchors will be As per Section D-1. Within the impact area sessile species will be killed. presence and damage to minimised The benthic community within the project area is typical for the CNS with no

movement of individuals y rare or protected species identified in the site surveys. Following removal of ible ible

r vessels g the anchors, recolonisation and recovery to pre—impact levels is likely to Likel Smothering li y g take place through immigration into the disturbed area over a period of one Mino Y Likely Moderate Local Low Short Minor 9.2 Ver Ne to five years.

REPORT REF: P1459BA_RN2525_REV0 A-8 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

F-2 Drilling of wells Discharge of Physical No mitigation envisaged Cuttings discharged at the seabed will have a direct impact on the benthic cuttings damage to community. Cuttings discharged through the water column could have an individuals impact on the benthic community as they settle out on the seabed. Smothering There will be a direct loss of any species on the seabed underneath the cuttings piles generated by drilling. However this will be localised and minor when compared to the extent of the CNS and physical disturbance from other activities such as trawling. Cuttings will be incorporated in the sediment through bioturbation and general sediment mobility. Significant erosion of cuttings piles starts when the seabed critical velocity reaches 0.35ms-1 (UKOOA 1999). Seabed currents (0.42ms-1) will ensure that all cuttings piles will disperse quickly, although there is the possibility that they may persist for a number of years. Experience in the CNS region indicates that cuttings piles will persist for 5- 10 years.

y As such, benthic communities underneath the cuttings piles will be directly ible ible

r g impacted however, due to the small scale and significant erosion potential of Likel li y g the surrounding region, a minor impact on benthic communities is Mino Y Very Likely Moderate Local Low Moderate Minor 9.2 Ver Ne anticipated. F-3 Drilling of wells Discharge of Potential toxic As per Section C-3 As per Section D-3. Components of the WBM e.g., barite and bentonite, are Installation of chemicals effects known to contaminate seabed sediments; the effects of which may be flowlines (including noticeable for 10 years after drilling has ceased. However, this does not WBM) impede the recolonisation of an area disturbed by drill cuttings and WBM. Small quantities of inhibition chemicals such as biocide and oxygen

y scavenger used in flowline commissioning will be discharged at seabed ible ible

r level. Any toxic impacts on benthic communities will be extremely localised, g Likel li y g restricted to the immediate area surrounding the discharge location and as Mino Y Very Likely Moderate Local Low Short Minor 9.2 Ver Ne such are unlikely to have a noticeable effect above individual level. F-4 Drilling of wells Discharge of Potential toxic As per Section C-4 As per Section D-4. Discharges will be at the sea surface in 80m water ible ible reservoir effects depth. The small quantity of oil to be discharged will have dispersed and r g li

hydrocarbons g diluted to below toxic levels and it is not expected will have an impact on Mino N ------9.2 Possible Ne benthic communities.

REPORT REF: P1459BA_RN2525_REV0 A-9 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

F-5 Installation of Physical Habitat loss The footprint of any structure will be As per Section D-5. flowlines presence of Physical minimised Sessile species in the impact footprint will be killed. The benthic community subsea damage to is typical of the CNS with no rare or protected species identified in the site infrastructure individuals surveys. The presence of subsea infrastructure will create new habitat for and flowlines those species that require hard substrate for anchoring, but it may take

Smothering Concrete y longer to establish a community due to the lack of larvae or adult sources in ible ible

Habitat creation r mattressing g the surrounding area. Likel li y and rock g Mino Minor Minor 9.2 Ver Y Very Likely Moderate Local Low Short protection Ne F-6 Installation of Trenching Habitat loss The impact will be minimised through The fluidisation of sediments may cause some fatalities of infauna, although flowlines and backfill careful route design. this will be limited to the width of the fluidised sediment (approximately 2m).

Physical damage to y The deposition of suspended sediments may smother sessile species and ible ible

r g filter-feeders along the pipeline corridor, but the extent of this impact will be Likel individuals li y g limited to a footprint no wider than 10m and the intensity of the impact will Mino Y Very Likely Moderate Local Low Short Minor 9.2 Ver Smothering Ne decrease with distance from the flowline. F-8 Installation of Anchoring Physical The footprint of the anchors will be The impact footprint of the FPSO anchors is extremely small. Sessile

FPSO damage to y minimised species in the immediate vicinity will be killed but there are no rare protected ible ible

r individuals g species in the project area. Benthic species are known to colonise hard Likel li y Smothering g substrates such as anchors and chains which are in position for a long Mino Y Very Likely Short Local Low Short Minor 9.2 Ver Ne period of time and it is likely that a new community form on the structures. G - Fish and shellfish G-1 Physical Anchoring Loss or The footprint of the anchors will be The footprint of anchor mounds and chains is not expected to significantly presence and disturbance of minimised. affect fish communities. movement of spawning and There is a possibility that pelagic fish species could collide with the anchor vessels nursery chains and become entangled whilst the drilling rig is on station. There is no grounds mitigation envisaged for this potential impact as it is a very minor risk.

y ible ible effecting stock r g

viability g Mino Ne Y Unlikely Short Local Low Short Minor 9.3 Collision risk Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-10 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

G-2 Physical Discharge of Organic As per Section C-1 Considering the active mitigation in place it is likely that any deterioration in presence and sewage, grey enrichment fish or shellfish will be transient. It is very unlikely that there will be any movement of water, food leading to residual impacts. vessels waste and raised biological drainage oxygen water demand. May increase plankton & fish populations ible ible

r changing g li balance of food g Mino N ------9.3 chain Possible Ne G-3 Physical Subsea noise Disturbance No mitigation envisaged As the majority of the noise generated by offshore oil installations is low presence and causing frequency (<1kHz), any impact is likely to be minimal. Noise from piling has movement of avoidance of the potential to have a greater impact; however, the duration of noise vessels spawning & generation from piling will be significantly less than that of general nursery construction (including drilling) and the noise generated by vessels present grounds during the construction period. ible ible

r Physical g li damage to g Mino Y Possible Short Local Low Short Minor 9.3 individuals Possible Ne G-4 Drilling of wells Discharge of Loss of No mitigation envisaged The impact on individual species is expected to be negligible, although cuttings spawning & demersal species could be affected through temporary disturbance or nursery ground habitat around drill centres. The deposition of drill cuttings on the seabed effecting stock has the potential to change the sediment so that it is no longer preferential viability as a spawning habitat. However, the area affected is extremely small when

y ible ible compared to the size of the spawning and nursery grounds used in the r Physical g li damage to g North Sea and any slight changes to spawning habits this might cause will Mino Ne Y Unlikely Moderate Local Low Moderate Minor 9.3 individuals Unlikel not affect stock recruitment or population viability.

REPORT REF: P1459BA_RN2525_REV0 A-11 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

G-5 Drilling of wells Discharge of Potential toxic As per Section C-3 During drilling and pipeline installation a variety of chemicals will be used. Installation of chemicals effects The majority of chemicals to be used are classified OCNS category E or flowlines (including Gold and therefore pose little risk to the marine environment. In some cases WBM) it will be necessary to use chemicals which have a lower environmental performance, with high toxicity, low biodegradation or the potential to ible ible

r g bioaccumulate. Conditions in the vicinity of the development are such that li g any discharge will be quickly dispersed and therefore exposure of fish and Mino Possible Ne shellfish to these chemicals will be reduced. N ------9.3 G-6 Drilling of wells Discharge of Potential toxic As per Section C-4 Discharges will be from the rig and will be rapidly dispersed and dissipated.

reservoir effects ible It is unlikely that the small volumes discharged will be present in the water

r g li

hydrocarbons g column for sufficient periods to pose a risk of toxic potential to fish species. Mino Ne N ------9.3 Unlikel

G-7 Installation of Physical Loss of The footprint of any structure will be Although activities will result in a loss of some spawning and nursery flowlines presence of spawning & minimised grounds, the development site makes up only a small percentage of the subsea nursery ground total spawning and nursery areas for these species in the North Sea. infrastructure effecting stock Therefore the impact on fish populations is expected to be minimal. and flowlines viability

Physical r damage to Low Low Mino N ------9.3 individuals Unlikel G-8 Installation of Trenching Loss of The impact will be minimised through The development is within the spawning and nursery grounds for five flowlines and backfill spawning & careful route design. species. However, jet trenching the water injection flowline will only disturb a nursery ground small area of seabed and will not change the sediment composition. effecting stock Species will be able to use the area again during the next season. Therefore viability the impact on fish populations is expected to be minimal.

y ible ible

r Physical g li damage to g Mino Ne N ------9.3 individuals Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-12 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

G-9 Installation of Concrete Loss of The footprint of any protective structures Using only the necessary amount of material will help mitigate against flowlines mattressing spawning & will be minimised unnecessary habitat loss. Although activities will result in a loss of some and rock nursery ground spawning and nursery grounds, the development site makes up only a small protection Physical percentage of the total spawning and nursery areas for these species in the damage to North Sea. Therefore the impact on fish populations is expected to be ible ible minimal. The presence of hard substrate may attract new species to the r individuals g li

g area. Mino Possible Ne N ------9.3 G-10 Installation of Anchoring Loss of The footprint of the anchors will be The footprint of the FPSO anchors is extremely small not expected to FPSO spawning & minimised significantly affect fish communities. nursery ground There is a possibility that pelagic fish species could collide with the anchor effecting stock chains and become entangled. There is no mitigation envisaged for this viability potential impact as it is a very minor risk. Physical

y ible ible damage to r g li

individuals g Mino Ne N ------9.3 Unlikel H - Seabirds H-1 Physical Increased Localised No mitigation envisaged It is possible that seabirds resting on the sea surface could be disturbed by presence and vessel activity disturbance of the presence of the drilling rig and support vessels. However, this is not ible ible movement of in region seabirds from considered to be a significant threat to seabirds due to the existing level of r g li

vessels the sea surface g shipping activity in the area. Mino N ------9.4 Possible Possible Ne

H-2 Drilling of wells Discharge of Potential toxic y As per Section C-3 Discharged materials will not be present within the water column for long chemicals effect enough or at high enough concentrations to pose a significant threat to the

Installation of ible nificant nificant g Unlikel

(including li seabird community. g flowlines y WBM) g Insi N ------9.4 Ver Ne

H-3 Drilling of wells Discharge of Potential toxic y As per Section C-4 Discharges will be from the rig and will be rapidly dispersed and dissipated. reservoir effect It is unlikely that the small volumes discharged will be present in the water ible ible nificant nificant g

hydrocarbons Unlikel column for sufficient periods to pose a risk to seabirds. li g

y g Insi N ------9.4 Ver Ne

REPORT REF: P1459BA_RN2525_REV0 A-13 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

I - Marine mammals

I-1 Physical Subsea noise Can cause JNCC guidelines (JNCC 2010) on ‘The The majority of subsea noise source levels generated by construction presence and physical injury protection of marine European Protected activities is generally below 180dB. High noise levels during rig move movement of or disturbance Species from Injury and Disturbance’ will activities have been recorded north of Scotland (Swift and Thompson 2000). vessels be followed. In particular EnQuest are Many marine mammals exhibit overt behavioural reactions at a received Installation of committed to following the mitigation noise level of 120dB for continuous noise, such as drilling. FPSO measures outlined in Appendix B – Noise levels in excess of 120dB may be tolerated for a period of time, but Statutory nature conservation agency the likelihood of behavioural response increases. Prolonged sound could protocol for minimising the risk of injury result in marine mammals moving away from preferred areas. However, to marine mammals from piling noise there is no definitive data to suggest that construction noise could adversely (August 2010). affect small cetaceans. It is an offence under the EC Habitats Directive to cause physical injury or to deliberately disturb wild animals of an EPS. The eight cetacean species which are observed in the project area are all considered EPS. The major source of underwater noise during construction will be from the piling of the FPSO anchors and riser tethers. Following the JNCC (2009) guidelines a noise assessment has been conducted to determine whether piling activity is likely to cause physical injury or deliberate disturbance. The assessment, presented in Section 9.5, concluded that as the sound experienced at 500m does not exceed the injury or deliberate disturbance thresholds, provided the mitigation measures are followed, there is a negligible risk of an offence

r under the Conservation (Natural Habitats &c) Regulations 1994 (as amended) and the Offshore Marine Conservation (Natural Habitats &c) Y Possible Short Local Medium Short Minor 9.5 Possible Possible Low Mino Regulation 2007 (as amended in 2010). I-2 Physical Anchoring Collision risk No mitigation envisaged. It is possible that marine mammals could collide with the anchor chains

y ible ible presence and used to hold the drilling rig in position. However this is not considered to be a r g li

movement of g significant threat to marine mammals as marine mammals should be able to Mino Ne N ------9.5 vessels Unlikel detect and avoid the chains.

REPORT REF: P1459BA_RN2525_REV0 A-14 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

I-3 Physical Discharge of Feeding As per Section C-1 C-1 concluded that there is not expected to be a residual impact on water presence and sewage, grey impairment due quality. Therefore, it is unlikely that marine mammals will be affected by the

movement of water, food to organic y discharge of sewage, grey water, food waste and drainage water. vessels waste and enrichment ible ible nificant nificant drainage effecting g Unlikel li g y water balance of food g Insi Ver N ------9.5 chain Ne I-4 Drilling of wells Discharge of Potential toxic As per Section C-3 During drilling and pipeline installation a variety of chemicals will be used. Installation of chemicals effect The majority of chemicals to be used are classified OCNS category E or HQ flowlines colour band Gold and therefore pose little risk to the marine environment. In

y some cases it will be necessary to use chemicals which have a lower environmental performance, with high toxicity, low biodegradation or the ible ible nificant nificant g potential to bioaccumulate. Conditions in the vicinity of the development are Unlikel li g y g such that any discharge will be quickly dispersed and therefore exposure of Insi N ------9.5 Ver Ne marine mammals to these chemicals will be reduced.

I-5 Drilling of wells Discharge of Potential toxic As per Section C-4 Discharges will be from the rig and will be rapidly dispersed and dissipated. y reservoir effect It is unlikely that the small volumes discharged will be present in the water

hydrocarbons ible column for sufficient periods to pose a risk of toxic potential to marine nificant nificant g Unlikel li g y g mammals. Insi N ------9.5 Ver Ne

J- Marine protected sites and species

J-1 Physical Anchoring Could affect y No mitigation envisaged. There are no marine protected areas within 40km. The nearest protected presence and integrity of site is the Dogger Bank potential Special Area of Conservation (pSAC) ible ible nificant nificant movement of protected site g which is approximately 78km south-east from the Alma southern drill centre. Unlikel li g y vessels g Due to the distance of the protected site from the development area, it is Insi N ------9.6 Ver Ne unlikely that there will be any impacts. J-2 Physical Subsea noise Can cause As per Section I-1 Eight species of cetacean are known to frequent the project area at certain presence and physical injury times of the year. All cetaceans are EPS. Section I-1 concluded that the

movement of or disturbance expected residual impact on marine mammals will be minor. vessels to protected r Y Possible Short Local Medium Short Minor 9.6 Drilling of wells species Possible Low Mino

REPORT REF: P1459BA_RN2525_REV0 A-15 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

J-3 Physical Discharge of Potential toxic As per Section C-1 Eight species of cetacean are known to frequent the project area at certain presence and sewage, grey effects on times of the year. All cetaceans are EPS. The impact on marine mammals movement of water, food protected was assessed in I-3. ible ible

r vessels waste and species g y li drainage g Mino Ne water Likel N ------9.6

J-4 Drilling of wells Discharge of Could affect y No mitigation envisaged. As there are no protected areas within 40km, no lasting effect on protected cuttings integrity of sites is expected. ible ible nificant nificant

protected site g Unlikel

li g y g Insi N ------9.6 Ver Ne

J-5 Drilling of wells Discharge of Potential toxic y As per Section C-3 Eight species of cetacean are known to frequent the project area at certain Installation of chemicals effect on times of the year. All cetaceans are EPS The impact on marine mammals ible ible nificant nificant g

(including protected Unlikel was assessed in I-4. li g

flowlines y WBM) species g Insi N ------9.6 Ver Ne

J-6 Drilling of wells Discharge of Potential toxic y As per Section C-4 Discharges will be from the rig and will be rapidly dispersed and dissipated. reservoir effect on It is unlikely that the small volumes discharged will be present in the water ible ible nificant nificant g

hydrocarbons protected Unlikel column for sufficient periods to pose a risk of toxic potential to any protected li g y species g species. Insi N ------9.6 Ver Ne

J-7 Installation of Physical Could affect No mitigation envisaged. As there are no protected areas within 40km, no lasting effect on protected y flowlines presence of integrity of sites is expected. ible ible

subsea protected site nificant g Unlikel

li g y infrastructure g Insi N ------9.6 Ver and flowlines Ne

J-8 Installation of Concrete Could affect y No mitigation envisaged. As there are no protected areas within 40km, no lasting effect on protected flowlines mattressing integrity of sites is expected. ible ible nificant nificant and rock protected site g Unlikel li

g y placement g Insi N ------9.6 Ver Ne

REPORT REF: P1459BA_RN2525_REV0 A-16 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

J-9 Installation of Trenching Could affect No mitigation envisaged. As there are no protected areas within 40km, no lasting effect on protected

flowlines and backfill integrity of y sites is expected. protected site Any suspended sediments from trenching are unlikely to travel far enough to ible ible nificant nificant g Unlikel li

g have a impact on protected sites outside of 40km. y g Insi Ver N ------9.6 Ne

J-10 Installation of Anchoring Could affect No mitigation envisaged. As there are no protected areas within 40km, no lasting effect on protected

FPSO integrity of y sites is expected. protected site ible ible nificant nificant g Unlikel li g y g Insi N ------9.6 Ver Ne

K - Commercial fisheries K-1 Physical Increased Exclusion from A 500m safety exclusion zone will be Fishing vessels will be excluded from the safety zone around the drilling rig presence and vessel activity fishing grounds enforced around the drilling rig at all for approximately 447 days. A 500m safety exclusion zone will also be in movement of in region Potential times. place along the flowline route as the flowlines are installed. vessels Safety collision risk The drilling rig and construction vessels The Alma development area is not considered to be a commercially exclusion will be appropriately lit and sound important ground for pelagic and demersal species. A total of 147.5 tonnes zones warnings will be broadcast in poor of fish and shellfish, worth approximately £130,233 are landed each year visibility. from the ICES rectangle (41F2) that covers the Alma development area. Users of the sea will be notified of the However, fishing vessels will have to relocate and therefore it is concluded

y presence and intended movements of that there will be a minor residual impact. ible ible

r g construction vessels via the Kingfisher Likel li y g fortnightly bulletins, Notices to Mariners Mino Y Very Likely Moderate Local Low Short Minor 10.1 Ver Ne and VHF radio broadcast. K-2 Physical Anchoring Anchor mounds The footprint of the anchors will be Anchor mounds are a common feature of the North Sea around oil and gas ible ible

r presence and could snag g minimised development areas. Seabed imagery of areas where anchoring has li movement of fishing gear g occurred in the past often shows the area criss-crossed by trawl marks. Mino Y Possible Moderate Local Low Short Minor 10.1 vessels Possible Ne K-3 Drilling of wells Discharge of Could snag None envisaged All cuttings piles will be within the 500m radius safety exclusion zones cuttings fishing gear established around the drill centres ible ible

r g li g Mino N ------10.1 Possible Possible Ne

REPORT REF: P1459BA_RN2525_REV0 A-17 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

K-7 Installation of Trenching Residual berms Users of the sea will be notified of the As the water injection flowline will be jet trenched into the seabed, it is

flowlines and backfill could snag presence of new structures via the unlikely that fishing gear will have the opportunity to become snagged during fishing gear y Kingfisher fortnightly bulletins, Notices to installation. As the methodology does not create berms or spoil piles, there ible ible

Mariners and VHF radio broadcast. will be no snagging hazards left after installation. r g Unlikel li y g Mino Ver N ------10.1 Ne

K-8 Installation of Concrete Could snag The footprint of any protective structures There is the possibility that trawled fishing gear could become snagged on flowlines mattressing fishing gear y will be minimised the concrete mattressing or rock protection. However, this will be avoided

and rock through minimisation of the footprint of any protective structures present. r Unlikel placement y The deposited rock used for flowline protection (if necessary) is designed to Y Very Unlikely Long Local Low Long Minor 10.1 Ver Low Low Mino have a sloped profile which will deflect trawl boards. L- Shipping

L-1 Physical Physical Exclusion zone The drilling rig and construction vessels The nearest shipping lane is within 2nm of the Alma development. Some presence and presence and could impede will be appropriately lit and sound shipping will be displaced from the immediate vicinity of the development; movement of movement of shipping lanes warnings will be broadcast in poor however there is ample sea room to do so. The 500m safety exclusion zone vessels vessels Increased visibility. around the drilling rig is intended to prevent potential collisions with any collision risk Users of the sea will be notified of the vessels that may be in the area. This will be enforced by a guard vessel. presence and intended movements of construction vessels via the Kingfisher fortnightly bulletins, Notices to Mariners and VHF radio broadcast.

y ible ible

r g A 500m safety exclusion zone will be li g enforced around the drilling rig at all Mino Ne Y Unlikely Moderate Local Low Moderate Minor 10.2 Unlikel times. M - Other marine users

M-1 Physical Physical Localised As per L-1 There is the potential for any recreational users to be displaced from the

presence and presence and displacement of area whilst construction is ongoing. However given the distance offshore movement of movement of other marine y there is unlikely to be any significant recreational use.

vessels vessels users ible nificant nificant g The 500m safety exclusion zone around the drilling rig is intended to prevent Unlikel li g y Increased g potential collisions with any vessels that may be in the area. This will be Insi N ------10.3 Ver collision risk Ne enforced by a guard vessel.

REPORT REF: P1459BA_RN2525_REV0 A-18 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

y nificance nificance g Section Section Likelihood Severit Si RIA? (Y/N) Likelihood Duration Spatial Extent Sensitivity Recoverability Significance section Report

M-2 Physical Anchoring Anchors could As per L-1 There is no existing oil and gas infrastructure present in the development

presence and impact other area. The nearest platform to the development is the Clyde platform, movement of existing y located 40.5km north west of the northern drill centre. All oil and gas

vessels infrastructure ible infrastructure present in the development area is old and abandoned. As nificant nificant g Unlikel li g y Increased g stated in the Gardline Geosurvey report (Gardline 2011) all wellheads have Insi Ver N ------10.3 collision risk Ne been removed and only seabed depressions remain to mark locations. N- Archaeology

N-1 Physical Anchoring Physical Follow BMAPA protocol for reporting The surveys did not identify any sites of archaeological importance. presence and damage to finds of archaeological significance However, there is the potential for undiscovered subsurface archaeological movement of undiscovered sites to be impacted by anchors. As the site has previously been subject to

vessels archaeology r oil and gas activity it is assumed the potential for such sites to be present is low. Should a feature be identified, then mitigation measures will be Low Low Mino Y Unlikely Short Local Medium Irreversible Minor 10.4 Unlikel revisited to ensure that the site is not disturbed. N-2 Installation of Physical Physical As per Section N-1 The surveys did not identify any sites of archaeological importance. flowlines presence of damage to However, there is the potential for undiscovered subsurface archaeological subsea undiscovered sites to be impacted by anchors. As the site has previously been subject to

infrastructure archaeology r oil and gas activity it is assumed the potential for such sites to be present is and flowlines low. Should a feature be identified, then mitigation measures will be Low Low Mino Y Unlikely Short Local Medium Irreversible Minor 10.4 Unlikel revisited to ensure that the site is not disturbed. N-3 Installation of Trenching Physical As per Section N-1 The surveys did not identify any sites of archaeological importance. flowlines and backfill damage to However, there is the potential for undiscovered subsurface archaeological undiscovered sites to be impacted by anchors. As the site has previously been subject to

archaeology r oil and gas activity it is assumed the potential for such sites to be present is low. Should a feature be identified, then mitigation measures will be Low Low Mino Y Unlikely Short Local Medium Irreversible Minor 10.4 Unlikel revisited to ensure that the site is not disturbed. N-4 Installation of Presence of Physical As per Section N-1 The surveys did not identify any sites of archaeological importance. FPSO FPSO and damage to However, there is the potential for undiscovered subsurface archaeological anchors undiscovered sites to be impacted by anchors. As the site has previously been subject to

REPORT REF: P1459BA_RN2525_REV0 A-19 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

A.3 Production

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

A – Air Quality A-1 Physical Exhaust gas Localised Ensure all machinery is maintained. Atmospheric emissions from exhaust gases will be low (Section presence, emissions deterioration in Use of cleaner low emission fuels 6.2.1). Pollutants will be dispersed and diluted to levels below operation and air quality health and environmental guidelines within 500m of the discharge maintenance Emissions a will be managed via a point. See Section 8.1.5 for full discussion. of FPSO new Pollution Prevention Control (PPC) permit that will be applied for Power generation will emit approximately 6.2 tonnes of NOx per

Physical before production commences annum and 3.7 tonnes of SO2 per annum. presence and Given the generally dynamic offshore, concentrations of NOx and movement of SOx are not expected to reach European Commission alert export tanker thresholds and there is not expected to be any residual impact on and supply regional air quality. vessels

y ible ible

r g li

g Mino Ne N ------8.1 Unlikel A-2 Flaring during Exhaust gas Localised Flare quantities will not exceed Atmospheric emissions from flaring will be low (Section 6.2.2). initial stages of emissions deterioration in those permitted in the Consent to Pollutants will be dispersed and diluted to levels below health and production air quality Flare. environmental guidelines within 500m of the discharge point. See Section 8.1.5 for full discussion.

Given the generally dynamic offshore, concentrations of NOx and SOx are not expected to reach European Commission alert thresholds and there is not expected to be any residual impact on regional air quality.

y ible ible

r g li

g Mino Ne N ------8.1 Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-20 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

B - Climate Change

B-1 Physical Exhaust gas Loading of Emissions associated with power Approximately 1,263 tonnes of CO2 will be emitted per year from presence, emissions greenhouse generation will be managed via an power generation during production, and approximately 8,371 operation and from power gases e.g., EU ETS permit tonnes of CO2 will be emitted per year from vessels associated with maintenance generation CO2, CH4, the production phase of the development (Section 6.2.1.1). As a of FPSO comparison the annual emissions represent 0.011% of UK Physical emissions from similar offshore activities in 2009. This is a relatively presence and minor contributor to annual UK emissions and is typical for a movement of standard oil development of this size. See Section 8.2.5 for full export tanker discussion. and supply vessels

r N ------8.2 Possible Low Mino

B-2 Flaring during Exhaust gas Loading of None envisaged Approximately 428 tonnes of CO2 will be emitted from gas flaring initial stages of emissions greenhouse during the initial stages of production (Section 6.2.1.2). As a production gases e.g., comparison the annual emissions represent 0.014% of UK CO2, CH4, emissions from similar offshore activities in 2009. This is a relatively minor contributor to annual UK emissions and is typical for a standard oil development of this size. See Section 8.2.5 for full discussion.

r N ------8.2 Possible Low Mino

REPORT REF: P1459BA_RN2525_REV0 A-21 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

C - Water Resource C-1 Physical Discharge of Localised Produced water discharge will be The base case is that all produced water will be re-injected. If the presence, produced deterioration in closely monitored to ensure that all system trips then a maximum of 95.4kg of oil could be discharged in operation and water water quality contaminants are at an acceptable one trip (at 30mgl-1 in 20,000bbls of PW) as it is unlikely that a trip maintenance level. Oil in water, chemical, would last all day. However, all PW will be processed to ensure of FPSO aromatic and radionuclide OIW concentrations are as low as possible and it is thought given concentrations will all be reported the previous recorded OIW discharge for the FPSO that via the appropriate OCR and OPPC concentrations of 15mgl-1 could be achievable (Section 6.2.2.1). permits Currents in the project area are of average strength for the CNS OIW concentrations will be within (0.2ms-1) and combined with wave action will disperse and dilute permitted levels chemical discharges during construction. Currents will refresh a 500m radius column of water surrounding the discharge location

within one and a half hours (Section 8.3). Given that discharges are y ible ible

r g

li expected to be one off events no lasting effect on water quality is g expected.

Mino Ne N ------Unlikel 8.3

C-2 Physical Discharge of Localised Daily recording of chemical use to All discharges will be risk assessed and be within permitted levels. presence, chemicals deterioration in allow more refined and efficient use. Currents in the project area are of average strength for the CNS -1 operation and water quality All chemical discharges will be risk (0.2ms ) and combined with wave action will disperse and dilute maintenance assessed and within the DECC chemical discharges during construction. Currents will refresh a

of FPSO r permitted levels as per the relevant 500m radius column of water surrounding the discharge location within one and a half hours (Section 8.3). No lasting effect on water

OCR chemical permit i.e., PON15D. N ------Possible Low Mino quality is expected. 8.3

REPORT REF: P1459BA_RN2525_REV0 A-22 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

C-3 Physical Discharge of Localised Every vessel will have and It is estimated that a maximum of 9,469m3 of sewage and grey presence, sewage, grey deterioration in implement a written waste water will be discharged to sea per year during production (Section operation and water, food water quality management plan, compliant with 6.2.2.2). Given the prevalent metocean conditions in the project maintenance waste and MARPOL 73/78. area (e.g., winds, waves, tides and currents), the relatively short of FPSO drainage Annex V (Garbage) is particularly field life (10 years) and the small cumulative volume of discharges, Physical water relevant. No plastics/plastic the marine environment will be able to rapidly assimilate the presence and containing material will be disposed discharges through natural bacterial action. It is expected that any movement of of at sea, regardless of location. degradation in water quality will be transient (limited to a few hours export tanker Paper & food wastes will only be after the discharge) and there will not be any residual impacts on and supply discharged outside the 12nm limit. water quality. vessels General household products will be selected that are environmentally benign. ible ible

r g li

g Mino N ------8.3 Possible Ne D -Seabed conditions D-1 Physical Discharge of Sediment As per Section C-1 Given the small amount of produced water that maybe discharge if presence, produced contamination water injection fails (Section 6.2.2.1), it is unlikely that there will be operation and water any residual impact on sediments. maintenance

y ible ible

r of FPSO g li

g Mino Ne N ------8.4 Unlikel D-2 Physical Discharge of Sediment As per Section C-2 The majority of chemicals used during production will not be presence, chemicals contamination discharged at the seabed. The only chemical likely to be discharged operation and at the seabed is the water-based subsea hydraulic control fluid. maintenance Small amounts of control fluid are discharged near the seabed from of FPSO the directional control valves when they are opened and closed. The typical discharge from all eight wellheads will be a total of 24m3 per year. No residual impact on sediment is expected.

r N ------8.4 Possible Possible Low Mino

REPORT REF: P1459BA_RN2525_REV0 A-23 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

E - Plankton E-1 Physical Discharge of Potential toxic As per Section C-1 Discharge volumes of produced water will be very small and presence, produced effect although sensitive to changes in water quality, the plankton operation and water community undergoes a continual change in individuals with those maintenance from the surrounding waters and therefore has extremely rapid of FPSO recovery rates. As per Section C-1, any discharge will not be present within the

y ible ible water column for long enough or at high enough concentrations to r g li

g pose a significant threat to plankton. Mino Ne N ------9.1 Unlikel E-2 Physical Discharge of Potential toxic As per Section C-2 All discharges will be risk assessed and be within permitted levels. presence, chemicals effect Although sensitive to changes in water quality, the plankton operation and community undergoes a continual change in individuals with those maintenance from the surrounding waters and therefore has extremely rapid of FPSO recovery rates. As per section C-2, discharged chemicals will not be present within

y ible ible the water column for long enough or at high enough concentrations r g li

g to pose a significant threat to plankton. Mino Ne N ------9.1 Unlikel E-3 Physical Discharge of Organic As per Section C-3 Cumulative discharge volumes will be very small and combined with presence, sewage, grey enrichment the prevalent metocean conditions in the project area; it is unlikely operation and water, food leading to that any discharges will lead to any measurable organic enrichment. maintenance waste and raised biological of FPSO drainage oxygen Physical water demand. May presence and change balance movement of of food chain. export tanker ible ible and supply r g li

vessels g Mino N ------9.1 Possible Ne

REPORT REF: P1459BA_RN2525_REV0 A-24 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

F - Benthic communities F-1 Physical Discharge of Potential toxic As per Section C-1 Any toxic impacts on benthic communities will be extremely presence, produced effect localised, restricted to the immediate area surrounding the operation and water discharge location and as such are unlikely to have a noticeable

y ible ible maintenance effect above individual level. r g li of FPSO g Any discharges will be at the surface from the FPSO into 80m water Mino Ne Unlikel depth so are unlikely to reach benthic communities. N ------9.2 F-2 Physical Discharge of Potential toxic As per Section C-2 The majority of chemicals used during production will not be presence, chemicals effect discharged at the seabed. The only chemical likely to be discharged operation and at the seabed is the water-based subsea hydraulic control fluid. maintenance Small amounts of control fluid are discharged near the seabed from

y ible ible

r of FPSO g the directional control valves when they are opened and closed. li g The typical discharge from all eight wellheads will be a total of 24m3 Mino Ne N ------9.2 Unlikel per year. No toxic impact on benthic communities is expected. G - Fish and shellfish G-1 Physical Discharge of Potential toxic As per Section C-1 Discharge volumes of produced water will be very small and any presence, produced effect toxic impacts on fish and shellfish will be extremely localised,

y ible ible

r operation and water g restricted to the immediate area surrounding the discharge location li maintenance g and as such are unlikely to have a noticeable effect above individual Mino Ne N ------9.3 of FPSO Unlikel level. G-2 Physical Discharge of Potential toxic As per Section C-2 A variety of chemicals to be used for well maintenance during the presence, chemicals effect operational life of the field (Table 6-16). All chemicals that are operation and injected for well maintenance will be in a closed system with no maintenance discharge to sea. he only chemical likely to be discharged at the of FPSO seabed is the water-based subsea hydraulic control fluid. Small amounts of control fluid are discharged near the seabed from the directional control valves when they are opened and closed. The typical discharge from all eight wellheads will be a total of 24m3 per

y ible ible

r g year. Conditions in the vicinity of the development are such that any li g discharge will be quickly dispersed and therefore exposure of fish Mino Ne N ------9.3 Unlikel and shellfish to these chemicals will be reduced.

REPORT REF: P1459BA_RN2525_REV0 A-25 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

G-3 Physical Discharge of Organic As per Section C-3 Section C-3 concluded that there will be no residual impact on water presence, sewage, grey enrichment quality as a result of the discharges. It is therefore unlikely that there operation and water, food leading to will be any residual impacts on fish and shellfish. maintenance waste and raised biological of FPSO drainage oxygen Physical water demand. May presence and change balance movement of of food chain.

y ible ible

r export tanker g li and supply g Mino Ne N ------9.3 vessels Unlikel G-4 Physical Subsea noise Localised No mitigation envisaged The majority of the noise generated by offshore oil installations is presence, disturbance low frequency (<1kHz). Fish are known to congregate around operation and production platforms and do not tend to show avoidance behaviour maintenance unless noise levels increase significantly above the norm, for of FPSO example if seismic or piling activity is being undertaken at the site. Physical

presence and y movement of ible ible nificant nificant export tanker g Unlikel li g y and supply g Insi N ------9.3 Ver vessels Ne H - Seabirds

H-1 Physical Discharge of Smothering y As per Section C-1 The volume of oil discharged in produced water will be minimal and presence, produced restricted to discrete one off events when the system trips. Oil will ible ible nificant nificant operation and water g not present within the water column for long enough or at high Unlikel li g y maintenance g enough concentrations to pose a significant threat to the seabird Insi N ------9.4 Ver of FPSO Ne community.

H-2 Physical Discharge of Potential toxic y As per Section C-2 Any discharged chemicals will not be present within the water presence, chemicals effect column for long enough or at high enough concentrations to pose a ible ible nificant nificant operation and g significant threat to the seabird community. Unlikel li g y maintenance g Insi N ------9.4 Ver of FPSO Ne

REPORT REF: P1459BA_RN2525_REV0 A-26 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

H-2 Physical Increased Localised No mitigation envisaged It is possible that seabirds resting on the sea surface could be

presence and vessel activity disturbance of y disturbed by the presence of the export tanker and supply vessels. movement of in region seabirds from However, this is not considered to be a significant threat to seabirds ible ible nificant nificant export tanker the sea surface g due to the existing level of shipping activity in the area. Unlikel li g y and supply g Insi Ver N ------9.4 vessels Ne I - Marine mammals I-1 Physical Presence of Collision risk No mitigation envisaged. It is possible that marine mammals could collide with the anchor presence, FPSO and chains used to hold the FPSO in position. However this is not

y ible ible operation and anchors considered to be a significant threat as marine mammals should be r g li

maintenance g able to detect and avoid the chains. Mino Ne N ------9.5 of FPSO Unlikel

I-2 Physical Discharge of Potential toxic y As per Section C-1 The volume of oil discharged in produced water will be minimal and presence, produced effect restricted to discrete one off events when the system trips. Oil will ible ible nificant nificant operation and water g not be present within the water column for long enough or at high Unlikel li g y maintenance g enough concentrations to pose a significant threat to marine Insi N ------9.5 Ver of FPSO Ne mammals.

I-3 Physical Discharge of Potential toxic y As per Section C-2 Any discharged chemicals will not be present within the water presence, chemicals effect column for long enough or at high enough concentrations to pose a ible ible

operation and g significant threat to marine mammals. Unlikel li y maintenance g Insentient N ------9.5 Ver of FPSO Ne I-4 Physical Subsea noise Can cause No mitigation envisaged. Levels of underwater noise generated by the FPSO, export tanker presence, physical injury and supply vessels are expected to be below disturbance operation and or disturbance thresholds outside the immediate area of the power generators and maintenance will not be at a level to disturb marine mammals or cause physical of FPSO injury. Physical presence and movement of

y ible ible

r export tanker g li and supply g Mino Ne N ------9.5 vessels Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-27 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

J - Marine protected sites and species J-1 Physical Discharge of Potential toxic As per Section C-1 Eight species of cetacean are known to frequent the project area at presence, produced effects through certain times of the year. All cetaceans are EPS. The impact on operation and water bioaccumulatio marine mammals was assessed in I-2 maintenance n of chemicals of FPSO and hydrocarbons in food chain

Smothering y

ible ible nificant nificant g Unlikel li g y

g Insi N ------9.6 Ver Ne J-2 Physical Discharge of Potential toxic As per Section C-2 Eight species of cetacean are known to frequent the project area at presence, chemicals effects through certain times of the year. All cetaceans are EPS. The impact on operation and bioaccumulatio marine mammals was assessed in I-3 maintenance n of chemicals of FPSO and hydrocarbons in

food chain y

ible ible nificant nificant g Unlikel li g y

g Insi N ------9.6 Ver Ne J-3 Physical Subsea noise Can cause As per Section I-4 Eight species of cetacean are known to frequent the project area at presence and physical injury certain times of the year. All cetaceans are EPS. The impact on movement of or disturbance marine mammals was assessed in I-4. export tanker to protected and supply species vessels

y ible ible

r g li

g Mino Ne N ------9.6 Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-28 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

K - Commercial fisheries K-1 Physical Presence of Exclusion from A 500m safety exclusion zone will Due to the presence of the FPSO and the new exclusion zones presence, FPSO and fishing grounds be enforced around the FPSO. around the drill centres, fishing vessels will be displaced from their operation and anchors Potential The FPSO will be appropriately lit fishing grounds. The combined area that will be affected by the maintenance Safety collision risk and sound warnings will be safety exclusion zones will be 2,356km. The 500m safety exclusion of FPSO exclusion broadcast in poor visibility. zone around the FPSO is intended to prevent potential collisions zones with fishing vessels in the area. This will be enforced by a guard Users of the sea will be notified of vessel. the presence of the FPSO and new safety exclusion zones via the However the Alma development area is not considered to be a Kingfisher fortnightly bulletins, commercially important ground for pelagic and demersal species. A Notices to Mariners and VHF radio total of 147.5 tonnes of fish and shellfish, worth approximately £130,233 are landed each year from the ICES rectangle (41F2) that

broadcast. y covers the Alma development area. ible ible

r g Likel li y g Mino Y Very Likely Moderate Local Low Moderate Minor 10.1 Ver Ne

K-2 Physical Increased Potential All vessels will comply with Vessel activity in the region will increase marginally with the export presence and vessel activity collision risk international navigation regulations tanker on site once every two weeks and visits from supply and movement of in region and codes. maintenance vessels occurring over approximately 144 days per export tanker year. and supply A moderate number of fishing vessels could be present in the area vessels at the same time, however all ships will follow standard international laws of the sea (as set out by the International Maritime Organisation (IMO)). ible ible As there will not be a vast increase in vessel activity in the area, the r g li

g standard laws of the sea are sufficient to mitigate any risks. Mino N ------10.1 Possible Ne

K-3 Presence of Physical Could snag Users of the sea will be notified of There is the possibility that trawled fishing gear could become subsea presence of fishing gear the presence of new structures via snagged on subsea infrastructure. The majority of the structures will infrastructure subsea the Kingfisher fortnightly bulletins, be within a 500m radius safety exclusion zone. The mitigation ible ible infrastructure and updates to Admiralty Charts. measures are thought to be sufficient to negate any residual r g li and flowlines g All subsea structures have been impacts. Mino N ------10.1 Possible Possible Ne designed to be fishing friendly

REPORT REF: P1459BA_RN2525_REV0 A-29 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

L - Shipping

L-1 Physical Presence of Exclusion zone As per Section K-1 The nearest shipping lane is within 2nm of the Alma development. presence, FPSO and could impede Some shipping will be displaced from the immediate vicinity of the operation and anchors shipping lanes development; however there is ample sea room to do so. An maintenance Increased average of 2-3 vessels per day transit within 12nm of the Alma of FPSO collision risk development. The 500m safety exclusion zone around the FPSO is intended to ible ible

r g prevent potential collisions with any vessels that may be in the area li g and will be enforced. The FPSO will be appropriately lit when Mino N ------10.2 Possible Ne required. L-2 Physical Increased Increased All vessels will comply with The nearest shipping lane is within 2nm of the Alma development.. presence and vessel activity collision risk international navigation regulations An average of 2-3 vessels per day transit within 12nm of the Alma movement of in region and codes. development and the presence of the export tanker every two ible ible

r export tanker g weeks is unlikely to be noticeable above the baseline. li and supply g Mino N ------10.2 vessels Possible Ne M - Other marine users

M-1 Physical Presence of Localised As per Section K-1 There is the potential for any recreational users to be displaced from presence, FPSO and displacement of the area for the life of the development (10 years). However given operation and anchors other marine the historical use of the area for oil and gas, there is little maintenance users recreational use of the area (Section 9.3). of FPSO Increased There is no existing oil and gas infrastructure present in the collision risk development area. The nearest platform to the development is the

Clyde platform, located 40.5km north west of the northern drill y centre. ible ible nificant nificant g The 500m safety exclusion zone around the development is Unlikel li g y g intended to prevent potential collisions with any vessels that may be Insi N ------10.3 Ver Ne in the area. This will be enforced by the guard vessel.

REPORT REF: P1459BA_RN2525_REV0 A-30 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

M-2 Physical Increased Increased All vessels will comply with There is the potential for any recreational users to be displaced from presence and vessel activity collision risk international navigation regulations the area for the life of the development (10 years). However given movement of in region and codes. the historical use of the area for oil and gas, there is little export tanker recreational use of the area (Section 9.3). and supply There is no existing oil and gas infrastructure present in the vessels development area. The nearest platform to the development is the

REPORT REF: P1459BA_RN2525_REV0 A-31 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

A.4 Accidental Events

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

A - Water Resource A-1 Chemical / Diesel, crude Localised Accidental spills will be kept to a A large number of chemicals will be used during construction hydrocarbon or chemical deterioration in minimum through training, good activities, particularly associated with well engineering. All chemicals release (< 1 spill water quality housekeeping and through will be risk assessed and permitted in the appropriate manner. tonne) (including storage/handling procedures e.g., Although spilt chemicals/diesel may have an acute toxic effect on OBMs) sumps, drains and bunding should immediate discharge they will be quickly diluted and dispersed in catch accidental spills. the water column. Currents within the project area will refresh a Management controls will be in column of water within 500m of the discharge point within one and a place to eliminate bunkering spills half hours, although it may take slightly longer for the water column e.g. only bunkering during day light to return to pre-impact levels if the chemical release is of sufficient and in good weather. quantity. A location specific OPEP will be in OBM chemical spills may take longer to disperse as the heavier oil place for drilling and production. has less of a tendency to evaporate. However a small spill is still

r The OPEP will detail all emergency likely to break up with a couple of days. procedures that will be in place to

N ------Possible Possible Low Mino minimise any spill. 8.3 A-2 Chemical / Diesel, crude Localised As per Section A-1 but in addition: A spill of <10 tonnes is more likely to occur during construction hydrocarbon or chemical deterioration in EnQuest has access to Tier 1, 2 activities, e.g., during bunkering. Diesel is a Group 2 oil which release (1-10 spill water quality and 3 oil spill response capabilities evaporates quickly on release. Typically 90% of a large diesel spill tonnes) (including through Oil Spill Response (OSR). evaporates or disperses naturally within the water column within OBMs) one to two days (ITOPF 2007). For a spill of <10 tonnes it is possible that it will have dispersed within a few hours. Crude oil or OBM chemical spills may take longer to disperse as the

r heavier oil has less of a tendency to evaporate. Mitigation measures in place should be sufficient to minimise the risk of a spill

Low Low Mino N ------Unlikel and any deterioration in water quality is likely to be transient. 8.3

REPORT REF: P1459BA_RN2525_REV0 A-32 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

A-3 Chemical / Diesel, crude Deterioration in As for A-2 but in addition: Three scenarios have been identified which could result in a spill of hydrocarbon or chemical water quality EnQuest is a member of OSPRAG crude oil or diesel >10 tonnes: loss of containment from the drilling release (>10 spill which will provide support in a well rig, total loss of inventory from the FPSO and total loss of inventory tonnes) (including blow out event. from the export tanker. A well blow out is highly unlikely given the OBMs) low reservoir pressures present at Alma (see Section 7.1.1). Control measures will be in place to ensure rapid response to loss of A diesel spill will very quickly evaporate and disperse in the marine pipeline containment. These will be environment. Oil spill modelling indicates the diesel inventory from outlined in the Alma OPEP. the drilling rig would naturally disperse or evaporate within 10 hours (see Section 7.3). Crude oil takes longer to disperse and an intervention response may be necessary to help break it up before it beaches on the shoreline. Water quality is likely to deteriorate in the immediate vicinity of the spill as hydrocarbons are dispersed through the water column.

y y However, it will be naturally biodegraded by microbes within one to two months (NOAA 2006). The concentration and likelihood of

r r natural biodegradation will obviously be dependent on the scale of Unlikel y

the incident. However, generally the deterioration in water quality Y Mino Ver Short Short Extensive Low Moderate Low Low Mino Very Unlikel will be short –term. 8.3 B -Seabed conditions B-1 Overboard Dropped Scour around Every reasonable measure will be Scour is likely around any object remaining on the seabed. loss of objects objects taken to retrieve dropped objects. However, given the mitigation measures in place any residual equipment or If the object cannot be retrieved a impacts are likely to be negligible. waste PON2 will be submitted to the DECC. A dropped objects plan will be ible ible

r g developed to address risk of li g dropping objects during construction

Mino N ------Possible Ne and operations. 8.4

REPORT REF: P1459BA_RN2525_REV0 A-33 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

B-2 Chemical / Diesel, crude Sediment As per Section A-1 A large number of chemicals will be used during construction hydrocarbon or chemical contamination activities, particularly associated with drilling the wells. All chemicals release (< 1 spill will be risk assessed and permitted in the appropriate manner. tonne) (including A spill <1 tonne is likely to be at the sea surface from the drilling rig,

OBMs)

r FPSO or support vessel, and would disperse within a couple of hours. Therefore, it is unlikely that hydrocarbons will reach the

- - - - Possible Low Mino N - - seabed. 8.4 B-3 Chemical / Diesel, crude Sediment As per Section A-2 The likelihood of a spill >0.1 tonnes occurring during construction is hydrocarbon or chemical contamination 24% for the Alma development. The majority of spills are likely to release (1-10 spill be at the sea surface or in the water column. The frequency of the

y y

r tonnes) (including r flowline failing is 0.00125 times per year. A spill of crude oil from the

OBMs) production flowline could contaminate sediments and persist for Short Short Local High Moderate Low Low Mino Y Mino Unlikel Unlikel some time however the extent will be localised. 8.4

REPORT REF: P1459BA_RN2525_REV0 A-34 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

B-4 Chemical / Diesel, crude Sediment As per Section A-3 Three scenarios have been identified which could result in a spill of hydrocarbon or chemical contamination crude oil or diesel >10 tonnes: loss of containment from the drilling release (>10 spill rig, total loss of inventory from the FPSO and total loss of inventory tonnes) (including from the export tanker. A well blow out is highly unlikely given the OBMs) low reservoir pressures present at Alma (see Section 7.1). Modelling shows that in the event of a worst case crude oil loss of 100,000m3 (87,000 tonnes) then there is a 1% chance of oil beaching along coastline of one of the countries bordering the North Sea. Trajectory modelling, presented in Section 7.3 and Appendix B, indicates that with a prevailing wind towards the UK coastline it will take approximately 200 hours for the spill to beach on the North Yorkshire coastline. Taking into consideration evaporation and dispersion approximately 86,393m3 of crude oil could beach along the coast. With a prevailing wind towards the nearest international boundary a crude oil spill would first cross the cross the UK / Norway median line (within 5 hours) and then the Norway/Denmark median line after 31 hours. Taking into consideration evaporation and dispersion approximately 161,742m3 of crude oil could beach along the Danish coast within 130 hours of the spill occurring. Any components that settle to the seabed will be naturally biodegraded by microbes within one to two months. Elevated concentrations of hydrocarbons may be noticeable in sediments close to the discharge point after a large spill. Given the previous use of the area for oil and gas development, levels of hydrocarbon contamination are not expected to rise over existing historical levels. Crude oil that beaches has the potential to contaminate beach sediments. However, as a spill of this magnitude is extremely rare it is highly unlikely that there will be a residual impact during this development.

r r Unlikel y

Ver Y Very Unlikely Short Extensive High Moderate Mino Low Low Mino 8.4

REPORT REF: P1459BA_RN2525_REV0 A-35 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

C - Plankton C-1 Chemical / Diesel, crude Potential toxic As per Section A-1 Accidental spills of chemicals will be rapidly diluted and dispersed in hydrocarbon or chemical effects the marine environment. It is expected that spilt materials will not be release (< 1 spill in the water column for long enough or at concentrations that are tonne) (including likely to pose a significant toxic effect to plankton. Although

OBMs) r vulnerable to a change in water quality the plankton community undergoes a continual change in individuals with the surrounding

Possible Low Mino N ------waters and therefore is not considered sensitive. 9.1 C-2 Chemical / Diesel, crude Potential toxic As per Section A-2. A hydrocarbon spill of <10 tonnes will be diluted and dispersed in hydrocarbon or chemical effect the marine environment within hours to at most one or two days. release (1-10 spill Concentrations of hydrocarbons may reach levels that pose a tonnes) (including significant toxic effect to plankton, but this is likely to be transient, OBMs) returning to background concentrations within a few tidal cycles.

r Although vulnerable to a change in water quality the plankton community undergoes a continual change in individuals with the

Low Low Mino N ------Unlikel surrounding waters and therefore is not considered sensitive. 9.1 C-3 Chemical / Diesel, crude Potential toxic As per Section A-3 Concentrations of hydrocarbons may reach levels that pose a hydrocarbon or chemical effects significant toxic effect to plankton. Although vulnerable to a change release (>10 spill in water quality the plankton community undergoes a continual

y tonnes) (including y change in individuals with the surrounding waters and therefore is OBMs) generally not considered sensitive. However, a major crude oil spill

r r does have the potential to affect a large area of water and therefore Unlikel y

there may be more extensive damage to plankton communities. Y Mino Ver Short Short Extensive High Short Low Low Mino Very Unlikel The likelihood of this happening is extremely rare. 9.1 D - Benthic communities D-1 Overboard Dropped Physical As per Section B-1 Sessile species within the immediate impact footprint of the dropped loss of objects damage to object are likely to be killed and species within the immediate vicinity equipment or individuals may be smothered by the repositioning of sediment. The benthic ible ible

r waste g community is typical of the CNS and no rare or protected species li g were identified in the site survey. Any impacts will be restricted to

Mino N ------Possible Ne individuals and not felt at a population level. 9.2

REPORT REF: P1459BA_RN2525_REV0 A-36 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

D-2 Chemical / Diesel, crude Smothering As per Section A-1 Accidental spills of chemicals will be rapidly diluted and dispersed in hydrocarbon or chemical Potential toxic the marine environment. The majority of spills are likely to be at the release (< 1 spill effects sea surface in water depths of approximately 80m (LAT). It is tonne) (including expected that spilt materials will not be in the water column for long OBMs) enough or at concentrations that are likely to pose a significant toxic effect to the benthic community. Any spill at the seabed would come

r from a rupture in the 10" production pipeline or from the wellheads. A spill of <1 tonne is likely to disperse and any toxic effects on

- - - - Possible Low Mino N - - benthic species are expected to be localised. 9.2 D-3 Chemical / Diesel, crude Smothering As per Section A-2 As per Section B-3. Spills from the surface are unlikely to reach the hydrocarbon or chemical Potential toxic seabed and pose a threat to the benthic community. release (1-10 spill effects Crude oil has the potential to smother benthic communities or tonnes) (including present a toxic risk if it reaches the seabed or is discharged at the OBMs) seabed. Individuals in the immediate vicinity of the spill location may be killed. However, the water column is likely to quickly dilute

r and disperse the spill and any toxic effects such that outside the immediate vicinity there are unlikely to be any residual impacts. The

Low Low Mino N ------Unlikel community as a whole is not expected to be affected. 9.2

REPORT REF: P1459BA_RN2525_REV0 A-37 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

D-4 Chemical / Diesel, crude Smothering As per Section A-3 Three scenarios have been identified which could result in a spill of hydrocarbon or chemical Potential toxic crude oil or diesel >10 tonnes: loss of containment from the drilling release (>10 spill effects rig, total loss of inventory from the FPSO and total loss of inventory tonnes) (including from the export tanker. A well blow out is highly unlikely given the OBMs) low reservoir pressures present at Alma (see Section 7.1). It is highly unlikely that oil will pool on the seabed so in most scenarios there is little direct risk to benthic communities of smothering. Elevated concentrations of hydrocarbons may be noticeable in sediments if the spill reaches the seabed which may affect community structure on a local scale. However, any change is unlikely to be sufficient to change the classification of sediments from unpolluted, and toxic effects on the benthic community are expected to be limited.

y y There is the possibility that if oil was to beach, those benthic communities in shallow waters would be smothered by emulsified

r oil. However, given the fact that a spill of the magnitude necessary Unlikel y

for oil to beach is highly unlikely, the EIA concluded that the Y Minor 9.2 Ver Short Short Extensive High Moderate Low Low Mino significance of an impact on benthic communities is minor. Very Unlikel E - Fish and shellfish E-1 Overboard Dropped Physical As per Section B-1 Sessile species within the immediate impact footprint of the dropped ible ible loss of objects damage to object are likely to be killed and species within the immediate vicinity r g li

equipment or individuals g may be smothered by the repositioning of sediment. Any impacts

Mino N ------Possible Ne waste will be restricted to individuals and not felt at a population level. 9.3 E-2 Chemical / Diesel, crude Potential toxic As per Section A-1 Discharged materials will not be present within the water column for hydrocarbon or chemical effects long enough or at concentrations that are likely to pose a significant

release (< 1 spill r toxic threat to fish communities as a whole. Concentrations outside tonne) (including the immediate discharge area/time will be close to background or

N ------Possible Possible Low Mino OBMs) undetectable. 9.3

REPORT REF: P1459BA_RN2525_REV0 A-38 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

E-3 Chemical / Diesel, crude Potential toxic As per Section A-2 Acute toxic effects to fish and shellfish species will be restricted to hydrocarbon or chemical effects the immediate area of the spill and for the duration of the spill release (1-10 spill release. However, high levels of toxic effects on fish spawning may tonnes) (including have longer term implications to stock levels. These long-term OBMs) chronic effects include reduced fecundity and breeding failure. However, it is likely that discharged materials will not be present within the water column for long enough or at concentrations that

r are likely to pose a significant toxic threat to marine ecology as a whole. Concentrations outside the immediate discharge area/time

Low Low Mino N ------Unlikel will be close to background or undetectable. 9.3 E-4 Chemical / Diesel, crude Potential toxic As per Section A-3 In fish life cycles the egg and juvenile stages are the most hydrocarbon or chemical effects vulnerable to toxicity in the water column, as adult fish are highly release (>10 spill mobile and generally able to avoid polluted areas. Localised tonnes) (including fatalities would occur in the immediate vicinity of the spill, but fish are OBMs) likely to avoid the area if the situation persists, and any effects are unlikely to be felt on a population level. As discussed in Section 9.3.2 the Alma development area lies within the spawning and nursery areas for mackerel, lemon sole, sprat, haddock and whiting (Coull et al. 1998). A major spill during a particular sensitive period could affect recruitment for that year. However, the spawning/nursery grounds span large areas of the North Sea which will mean that long-term changes to populations are minor. In general, lighter refined petroleum products such as diesel and gasoline are more likely to mix in the water column and are therefore more toxic to marine life. However, they tend to evaporate quickly (as demonstrated in Section 7.3) and do not persist long in

y y the environment. Although heavier residual oils tend to have specific gravities greater than sea water, causing them to sink once

r r spilled, the reservoir oil at Alma is light crude which is unlikely to Unlikel y

sink. A major hydrocarbon spill has therefore been assessed as Y Mino Ver Moderate Moderate Extensive Medium Moderate Low Low Mino Very Unlikel having the potential for an impact of minor significance on fish. 9.3 F - Seabirds

REPORT REF: P1459BA_RN2525_REV0 A-39 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

F-1 Overboard Discharge of Potential toxic As per Section B-1 It is possible that seabirds could ingest large items of refuse which

loss of waste items effect r typically causes the death of the affected birds. However the equipment or such as mitigation in place is sufficient to negate any residual impacts. Low Low Mino waste plastic bags Unlikel N ------9.4 F-2 Chemical / Diesel, crude Potential toxic As per Section A-1 Accidental spills of chemicals will be rapidly diluted and dispersed hydrocarbon or chemical effects with the marine environment. Uptake of toxic chemicals by plankton release (< 1 spill can have effects throughout the food chain, either as a result of tonne) (including direct mortality of food species or through transmission of OBMs) bioaccumulating chemicals to higher trophic levels. Discharged materials will not be present within the water column for long enough or at concentrations that are likely to pose a significant toxic threat to marine ecology as a whole. Concentrations outside the immediate discharge area/time will be close to background or undetectable. Hydrocarbon releases have the potential to smother seabirds. Oil spill effects include mortality by ingesting oil from feathers during

r preening, as well as by hypothermia from matted feathers. However, spills < 1 tonne generally disperse within a few hours and N ------9.4 Possible Possible Low Mino are unlikely to present a risk to seabirds F-3 Chemical / Diesel, crude Smothering As per Section A-2 The likelihood of a spill >0.1 tonnes occurring during construction is hydrocarbon or chemical Potential toxic 24% for the Alma development. These spills are likely to be at the release (1-10 spill effects sea surface and would disperse within a couple of hours to a few tonnes) (including days depending on the type of hydrocarbon spilt.

OBMs) Hydrocarbon releases have the potential to smother seabirds. Oil spill effects include mortality by ingesting oil from feathers during preening, as well as by hypothermia from matted feathers. However, overboard spills between 1 and 10 tonnes generally

r disperse within a few days depending on the type of hydrocarbon spilt. The mitigation measures, when implemented, should be Low Low Mino N ------9.4 Unlikel sufficient to prevent smothering of more than a few individuals.

REPORT REF: P1459BA_RN2525_REV0 A-40 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

F-3 Chemical / Diesel, crude Smothering As per Section A-3 Modelling shows that in the event of a total loss of containment from hydrocarbon or chemical Potential toxic the FPSO and/or export tanker (due to collision with each other), release (>10 spill effects there is the potential for impact over a widespread area. However tonnes) (including the likelihood of an incident of this magnitude occurring is unlikely.

OBMs) A well blow out is unlikely to occur due to low reservoir pressures. A spill of the magnitude modelled above is likely to significantly impact populations of seabirds. Seabirds that spend the majority of their time on the sea surface are most vulnerable as birds can be smothered by oil, or their feathers can become contaminated with hydrocarbons, which in turn may be ingested. Seabird vulnerability to hydrocarbon pollution is generally low for most of the year, with a significant increase in vulnerability in January and October. Should a spill occur during one of these sensitive periods an intervention response may be required to minimise the risk of smothering and species injury. It is highly unlikely that a spill of the magnitude

y y discussed above will occur. Mitigation measures outlined in the OPEP and management controls to eliminate spills should prevent any sizeable spills. Given the likelihood of an impact occurring is Unlikel y h g

unlikely the EIA concluded that significance of the impact is Y Moderate 9.4 Ver Long Long Extensive Very High Long Hi Moderate Moderate moderate. Very Unlikel G - Marine mammals G-1 Overboard Discharge of Potential toxic As per Section B-1 It is possible that marine mammals could ingest large items of

loss of waste items effect r refuse which typically causes the death of the affected animal. equipment or such as However the mitigation in place is sufficient to negate any residual Low Low Mino N ------9.5 waste plastic bags Unlikel impacts. G-2 Chemical / Diesel, crude Potential toxic As per Section A-1 Accidental spills will be diluted and dispersed within the marine hydrocarbon or chemical effect environment. Spilt materials will not be present within the water release (< 1 spill column for long enough or at concentrations that are likely to pose a

tonne) (including r significant toxic threat to marine mammals. Concentrations outside OBMs) the immediate discharge area/time will be close to background or N ------9.5 Possible Possible Low Mino undetectable.

REPORT REF: P1459BA_RN2525_REV0 A-41 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

G-3 Chemical / Diesel, crude Potential toxic As per Section A-2 The likelihood of a spill >0.1 tonnes occurring during construction is hydrocarbon or chemical effect 24% for the Alma development. These spills are likely to be at the release (1-10 spill sea surface and would disperse within a couple of hours to a few tonnes) (including days depending on the type of hydrocarbon spilt. OBMs) Discharged materials will not be present within the water column for long enough or at concentrations that are likely to pose a significant

toxic threat to marine ecology as a whole. r In addition, a spill of this size could be easily avoided by these Low Low Mino N ------9.5 Unlikel mobile animals.

REPORT REF: P1459BA_RN2525_REV0 A-42 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

G-4 Chemical / Diesel, crude Potential toxic As per Section A-3 There is the potential that marine mammals could be significantly hydrocarbon or chemical effect affected if a large crude oil spill was to occur. Although the region release (>10 spill surrounding the Alma development is not considered to be tonnes) (including particularly important for marine mammals, pods and individuals OBMs) have been observed throughout the year. Should a major release of crude oil occur, there is the potential that individuals could be affected. In addition should any oil reach the shoreline, haul out sites for pinnipeds may be impacted. Pinnipeds are particularly sensitive between October and January when they are on land pupping and again between February and March during their annual moult. Neonatal pups are particularly at risk from oil coming ashore. Cetaceans have smooth hairless skins over a thick layer of insulating blubber, so oil is unlikely to adhere persistently or cause a breakdown in insulation. Marine mammals must surface to breathe and they may inhale vapours given off the spilt oil and their eyes may be vulnerable to major pollution. Indirect effects may also be caused through contamination and depletion of food resources. Due to the transient nature of cetaceans, it is likely that individuals not in the immediate area of the spill when it occurs will avoid the area and it is possible that the number of individuals affected could be small. However, if a substantial number of a population where affected there could be knock on effects to breeding and the long- term viability of the population. Recovery rates of land based marine mammals such as seals could be longer particularly if a spill affected a breeding season. All cetaceans are protected under the EC Habitats Directive as EPS and are classed as ecologically important. Although a major oil spill could have a significant impact on marine mammals the EIA concluded that the significance of the impact was minor based on the fact that a spill of this magnitude is extremely unlikely to occur.

y y

r r Unlikel y

Y Mino Ver Moderate Moderate Extensive Very High Moderate Medium Medium Mino Very Unlikel 9.5

REPORT REF: P1459BA_RN2525_REV0 A-43 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

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y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

H - Marine protected sites and species H-2 Chemical / Diesel, crude Smothering of As per Section A-1 There are no protected sites within 40km of the Alma development hydrocarbon or chemical protected area and a spill of <1 tonne is unlikely to travel far before being release (< 1 spill species dispersed.

tonne) (including

Potential effects r Marine mammals are a European Protected Species and are likely OBMs) on integrity of a to be present in the vicinity of the project area. The impact of an protected site Possible Low Mino accidental spill on marine mammals was assessed in G-2 N ------9.6 H-3 Chemical / Diesel, crude Smothering of As per Section A-2 There are no protected sites within 40km of the Alma development hydrocarbon or chemical protected area and a spill of <10 tonnes is unlikely to travel far before being release (1-10 spill species dispersed. tonnes) (including Potential effects Marine mammals are a European Protected Species and are likely OBMs) on integrity of a to be present in the vicinity of the project area. The impact of a

protected site r release of hydrocarbons (< 10 tonnes) on marine mammals was assessed in G-2. Low Low Mino N ------9.6 Unlikel

REPORT REF: P1459BA_RN2525_REV0 A-44 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

H-4 Chemical / Diesel, crude Smothering of As per Section A-3 There is the potential that protected sites and species could be hydrocarbon or chemical protected significantly affected if a large crude oil spill was to occur. The release (>10 spill species impact on protected species of marine mammals and seabirds are tonnes) (including Potential effects discussed in Sections F-3 and G-4 above. OBMs) on integrity of a Although there are no designated protected sites within 40km of the protected site Alma field, modelling shows that in the event of a total loss of containment from the FPSO and/or export tanker (due to collision with each other), there is the potential for impact over a widespread area and the possibility of crude oil beaching on the coastline. There are numerous protected areas along the coastline of the North Sea that could potentially be affected. Should a spill occur that could potentially affect a protected area an intervention response would be required. It is highly unlikely that a spill of the magnitude discussed above will occur. Mitigation

measures outlined in the OPEP and management controls to y eliminate spills should prevent any sizeable spills. As the likelihood of such a spill occurring is extremely rare the EIA concluded that Unlikel y significance of the impact is minor.

Y Minor 9.6 Ver Medium Medium Moderate Very Unlikely Very Unlikely Moderate Extensive Very High Moderate

I - Commercial fisheries I-1 Overboard Dropped Could snag As per Section B-1 The mitigation measures in place are considered sufficient to ible ible

r loss of objects fishing gear g reduce the impact on commercial fishing. li equipment or g Mino N ------10.1 waste Possible Ne I-2 Chemical / Diesel, crude Potential As per Section A-1 Accidental spills of chemicals will be rapidly diluted and dispersed hydrocarbon or chemical decrease in with the marine environment. Spilt materials will not be present release (< 1 spill catch if stocks within the water column for long enough or at concentrations that tonne) (including affected are likely to pose a significant toxic threat to marine ecology as a

OBMs) r whole. Concentrations outside the immediate discharge area/time will be close to background or undetectable. Therefore there is N ------10.1 Possible Low Mino unlikely to be a knock-on effect on commercial fisheries.

REPORT REF: P1459BA_RN2525_REV0 A-45 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

I-3 Chemical / Diesel, crude Potential As per Section A-2 Acute toxic effects to fish and shellfish species will be restricted to hydrocarbon or chemical decrease in the immediate area of the spill and for the duration of the spill release (1-10 spill catch if stocks release. However, high levels of toxic effects on fish spawning may tonnes) (including affected have longer term implications to stock levels. These long-term OBMs) chronic effects include reduced fecundity and breeding failure. However, it is likely that spilt materials will not be present within the water column for long enough or at concentrations that are likely to

r pose a significant toxic threat to marine ecology as a whole. Concentrations outside the immediate discharge area/time will be Low Low Mino N ------10.1 Unlikel close to background or undetectable.

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Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

I-4 Chemical / Diesel, crude Potential As per Section A-3 Modelling shows that in the event of a total loss of containment from hydrocarbon or chemical decrease in the FPSO and/or export tanker (due to collision with each other), release (>10 spill catch if stocks there is the potential for an extensive area of the North Sea to be tonnes) (including affected affected. However an incident of this magnitude is unlikely. OBMs) Damage to A major crude oil spill has the potential to damage fishing vessels boats and gear passing through the project location at the time of the event and has the potential to cause a decrease in catch if fish stocks are affected. It is expected that if boats are present in the area at the time of a spill they will be able to avoid the slick so it is considered highly unlikely gear or boats will be damaged. However, vessels may be excluded from the affected area during the clean-up operations. Generally, for short periods of time the fishing industry can relocate to other grounds without any detrimental impacts to catch, but a spill that affects large areas of sea may make it harder to relocate. It fish stocks are contaminated they make take a number of years to recover and fishing grounds could be closed with substantial loss of income for industry. Experience from major spills has shown that the long-term effects on wild fish stocks are unlikely because the normal over-production of eggs provides a reservoir to compensate for any localised losses. However, there could be a loss of market confidence as people may be unwilling to buy fish caught in a contaminated area.

Although the potential impacts could be of major significance to the y fishing industry the fact that a spill of the magnitudes discussed

above is highly unlikely has meant that the EIA concluded the r Unlikel

y residual impact is of minor significance.

Y Minor 10.1 Ver Medium Medium Mino A well blow out is unlikely to occur due to low reservoir pressures. Very Unlikely Moderate Extensive Medium Moderate J- Shipping J-1 Overboard Dropped Could cause As per Section B-1. The mitigation measures in place are considered sufficient to

loss of objects hazard to reduce the impact on shipping. r equipment or shipping N ------10.2 waste Possible Low Mino

REPORT REF: P1459BA_RN2525_REV0 A-47 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

J-2 Chemical / Diesel, crude Damage to As per Section A-3 Modelling shows that in the event of a total loss of containment from hydrocarbon or chemical vessels the FPSO and/or export tanker there is the potential for an extensive release (>10 spill Restrictions on area of the North Sea to be affected. However, an incident of this tonnes) (including shipping lanes magnitude is unlikely. A well blow out is unlikely to occur due to low OBMs) reservoir pressures. If the spill is extensive then shipping lanes in the region could be closed to allow the oil spill response to be undertaken. It is possible that shipping lanes could be routed around the affected area but

y there might be financial implications associated with longer routes and delays. As the event is unlikely to occur the residual impact has

r r Unlikel

y been assessed as of minor significance.

Y Mino Ver Low Low Mino Very Unlikely Short Extensive Medium Short 10.2 10.2

K - Other marine users K-1 Overboard Dropped Could cause As per Section B-1 The mitigation measures in place are considered sufficient to loss of objects hazard to reduce the impact on other marine users. equipment or shipping waste ible ible

r g li g Mino N ------10.3 Possible Possible Ne

REPORT REF: P1459BA_RN2525_REV0 A-48 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Determination of Potential Impact EIA Consideration of Mitigation Measures Residual Impact Assessment Project Aspect Potential Mitigation Measures Identification of Residual Impact Considering Severity Factors Activity Impact Mitigation Measures

y nificance nificance g Likelihood Severit Si (Y/N) RIA? Likelihood Duration Spatial Extent Sensitivity Recoverability Significance Report section Section Section

K-4 Chemical / Diesel, crude Damage to As per Section A-3 Modelling shows that in the event of a total loss of containment from hydrocarbon or chemical vessels the FPSO and/or export tanker there is the potential for an extensive release (>10 spill Restricted area of the North Sea to be affected. However, an incident of this tonnes) (including access magnitude is unlikely. A well blow out is unlikely to occur due to low OBMs) reservoir pressures. If crude oil reaches the coastline, nearshore activities could be affected if restrictions are imposed to assist with the response operation. There may also be knock-on effects on the tourist industry if the spill beaches in substantial quantities. As the

y likelihood of such an event occurring is Very Unlikely, the EIA concluded that the residual impact is of minor significance.

r Unlikel y Y Very Unlikely Short Extensive Medium Short Minor 10.3 Ver Medium Medium Mino

L - Archaeology L-1 Overboard Dropped Physical Follow BMAPA protocol for The surveys did not identify any sites of archaeological importance. loss of objects damage to reporting finds of archaeological However, there is the potential for undiscovered subsurface

equipment or undiscovered y significance archaeological sites to be impacted by dropped objects. As the site waste archaeology has previously been subject to oil and gas activity it is assumed the

r potential for such sites to be present is low. Should a feature be Unlikel

y identified, then mitigation measures will be revisited to ensure that 5 N ------10. Ver Low Low Mino the site is not disturbed.

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Appendix B Oil Spill Modelling

REPORT REF: P1459BA_RN2525_REV0 B-1 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

B.1 Introduction

This report is to support the Environmental Statement for the Alma Development Area (DECC ref no. D/4110/2011) and to meet the latest Department of Energy and Climate Change (DECC) guidance letter regarding hydrocarbon release assessment recently released to industry (23 December 2010). The guidance states that the ES assessment of potential impacts from hydrocarbon releases must be extended to match the scope of the recently amended oil pollution emergency plan (OPEP) guidelines.

B.2 Alma Field Development

The Alma Field development is a small development located in the UKCS Blocks 30/24 and 30/25, in the Central North Sea (CNS). It lies in water depths of approximately 80m and is 274km east of the nearest landfall on the Northumberland coastline and 18.5km west of the UK/Norwegian international boundary (median line). Nearby fields include Orion and Auk (to the north- west) and Flora, Fife and Angus (to the south-east). A total of eight wells are to be as part of the field development, six production wells (northern drill centre) and two water injection wells (southern drill centre). The coordinates for the wells are provided in Table B-1 below. Drilling will be conducted from a semi-submersible mobile drilling unit (MoDU). EnQuest have a number of rig options that they are considering. They currently have the Transocean John Shaw semi-submersible MoDU on contract and it is possible that this rig could be used at Alma. If it is not available, due to EnQuest’s other drilling commitments, a semi-submersible with a similar specification could be used. Table B-1: Project co-ordinates Structure Easting (E) Northing (N) Latitude (N) Longitude (E) Uisge Gorm FPSO 488 250 6 227 000 56° 11' 16.16" 02° 48' 38.45" Northern drill centre (production wells) 485 469 6 228 541 56° 12' 05.72" 02° 45' 56.84" Southern drill centre (water-injection wells) 485 858 6 224 891 56° 10' 07.71" 02° 46' 20.12" Datum: WGS84 The two drill centres will be tied-back to the Uisge Gorm floating, production, storage and offloading (FPSO) vessel. Two new 3km, 10-inch buried production flowlines and one 2.5km 10-inch buried water-injection flowline will be installed. A chemical umbilical will also be installed out to both drill centres and a power cable will be laid out to the production drill centre. A shuttle tanker will visit the FPSO once every two weeks to offload crude oil via a loading hose and tanker mooring system. EnQuest will submit an OPEP to the DECC Offshore Inspectorate for approval to cover the drilling and production activities on the field. The OPEP will comply with the requirements of The Offshore Installations (Emergency Pollution Control) Regulations 2002 and The Merchant Shipping (Oil Pollution Preparedness, Response Co-operation Convention) Regulations 1998 and take into consideration recent revised guidance from the DECC following the Gulf of Mexico Macondo incident.

REPORT REF: P1459BA_RN2525_REV0 B-2 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

B.3 Worst Case Oil Spill Modelling

Three scenarios have been identified within the project scope as potential sources for a major spill of hydrocarbons:

Loss of diesel inventory from the FPSO and tanker through collision – 2,400m3 (2,016 tonnes) from the FPSO and 3,430m3 (2,881 tonnes) from the export tanker

Loss of crude oil inventory from the FPSO and tanker through collision – A maximum of 94,500m3 (81,0901 tonnes) from the FPSO and a maximum of 100,000m3 (87,000 tonnes) from the export tanker (note: neither vessel will be full at the same time) 3 Loss of diesel inventory from the drilling rig – 1,665m (1,399 tonnes) The most recent UK guidance on oil pollution emergency response requires Operators to model a loss of well control (blow out), as this although an extremely rare occurrence in the UK is considered to be the worst case volume of crude oil that could be spilt from a development. After consultation with the DECC Offshore Inspectorate this modelling has not be run for the Alma development due to the low reservoir pressure. From the very start of field life, reservoir pressure is such that ESPs will be required to pump crude oil out of the reservoir. In the event that well control is lost the wells will effectively self- kill. Instead, the worst case crude spill was considered to be if the FPSO and export tanker collided, with a total loss of containment. During production from Alma the worst case scenario is for full loss of containment from both the FPSO and export tanker due to collision (with each other). If this were to happen, a maximum of 5,830m3 (4,897 tonnes) of diesel (from FPSO and tanker combined) and 100,000m3 (87,000 tonnes) of crude oil would be released instantaneously. The 100,000m3 of crude oil represents the maximum (larger) capacity of the export tanker as neither vessel will be full at the same time. The diesel volume is the combined inventory of both vessels. Modelling was not undertaken for a diesel spill from the drilling rig as it was a smaller volume than that of the combined FPSO and export tanker volume. Therefore it can be inferred that the extent of the spill would be less. Oil Spill Response (OSR) was commissioned to undertake oil spill modelling of these scenarios using OSIS 5.0 software (OSR 2011). The Oil Spill Information System (OSIS), developed by BMT Cordah Ltd, is an oil spill model that predicts the movement of oil on the water surface and the distribution of oil in the marine environment. It is a fully validated and calibrated oil spill model based upon extensive research conducted by Warren Spring Laboratories and subsequently AEA Technology plc. The weathering model within OSIS has been validated against controlled actual spills at sea and real spill events supported with laboratory calibration. The model has a number of limitations that should be considered when interpreting the results:

Modelling results are for guidance purposes only and response strategies should not be based solely on modelling results alone.

The resolution / quality of tidal and oceanic current data varies between regions and models. As with any other model, results are dependent on the quality of the environmental parameters and scenario inputs used.

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The properties of the oil in the model’s database may not precisely match those of the product spilled.

If the same scenario was conducted in another oil spill modelling programme, with identical parameters and inputs, the results may show a degree of variance. This is expected as the different fate and weathering models have been developed and programmed independently. In addition the following assumptions were made when commissioning the models:

A ‘worst case’ air temperature of -6°C and sea temperature of 6°C were used as representative of temperatures in January to depict the fate of the spilled oil in its most viscous and persistent form.

Wind data was taken from the Met Office European model (56.0°N 3.14°E Jan 1998 - Nov 2008). The January wind rose selected as the closest representative example was compiled from a historical data set sourced by the Admiralty from the UK Met Office and covers a period between 1998 and 2008.

The principal tidal current data used was taken from http://www.visitmyharbour.com/articles/article.asp?arturn=1314.

The oils specified for modelling were marine diesel and Ardmore crude. Ardmore crude is not in the OSIS oil database but oil matching was undertaken to find suitable substitute oil within the OSIS database. Auk has a similar density (API 38.16), specific gravity (0.834) and geographical location to the Ardmore crude (API 38 and SG 0.8329) and so was selected as the most appropriate oil. As the worst case spill was based on an instantaneous release, the model was run for a period of 417 days, which for planning purposes is believed to be more than sufficient. It is likely that beaching will occur within this period for the worst case scenarios in the UKCS (depending upon the oil type, meteorological conditions and location of the spill release point).

B.4 Spill Scenarios and Modelling Results

In accordance with the DECC guidelines on oil spill modelling for OPEPs, the scenarios were modelled using two types of models: Stochastic - A stochastic model, also known as a probability model shows the probability of where an oil spill may impact for defined periods of time for a range of prevailing wind directions. The model uses historical wind data to run a series of trajectories for the various wind directions. It then combines the results to produce an overall illustration of the probability of where oil might travel to in the defined period of time. This type of modelling is an important tool for determining the areas of coastline that could potentially be affected by a spill and therefore the best locations to place oil spill response equipment. However, this type of diagram is typically the most misunderstood part of an Environmental Statement or Oil Pollution Emergency Plan. The most important thing to note is that it does not illustrate the extent of an oil spill, should a collision occur. Trajectory - A trajectory or deterministic model are used to predict the route of an oil slick over time and under certain metocean conditions. UK legislation requires two trajectory models are undertaken for each spill scenario

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investigated by the oil and gas industry; one trajectory using a 30 knot wind blowing towards the nearest stretch of UK coastline; and one trajectory using a 30 knot wind blowing towards the closest international boundary. For the Alma development two stochastic and four trajectory models were commissioned. The scenarios and volumes modelled are presented in Table B-1 below. Table B-2 presents a summary of the fates of the spills as illustrated in Figures B-1 to B-6. For the trajectory models, the red lines show the direction of the leading edge of the spill where as the black dots show the areas which the oil is likely to spread to. Table B-2: Spill scenarios modelled Model run Scenario Hydrocarbon Type of spill Quantity (m3) Conditions type 1 Stochastic N/A Loss of entire 2 inventory e.g. 100,000 Trajectory 30 knot onshore wind (towards UK) Crude oil during a (Instantaneous) 30 knot offshore wind (towards 3 collision Trajectory nearest international boundary e.g. UK/Norway) 4 Stochastic N/A 5 Trajectory 30 knot onshore wind (towards UK) Loss of entire 5,830 Diesel 30 knot offshore wind (towards inventory (Instantaneous) 6 Trajectory nearest international boundary e.g. UK/Norway)

Table B-3: Modelling results Scenario Model run type Fate of spill, as modelled

Figure B-1 Depending on the prevailing wind conditions at the time of the spill, there is a1% chance of oil beaching along the coastlines of one of the countries that border the North Sea. Modelling 1 Stochastic indicates that the spill will have naturally dispersed within the water column or beached within 417 days. There are numerous protected sites that could be affected by a spill of this size (see Section 9.6 for assessment). Figure B-2 There is the potential that crude oil will beach on the north Yorkshire coastline within 8 days Trajectory and 10 hours of the incident. Modelling indicates that approximately 86,393m3 would beach, 2 towards UK 38,972m3 will evaporate and 43,750m3 will disperse naturally. On this trajectory possible beaching locations are within the Teesland and Cleveland Coast Ramsar site and the Beast Cliff - Whitby (Robin Hood’s Bay) SAC protected area. Figures B-3 There is the potential that the spill will cross the UK/Norway international boundary (median line) within 5 hours of the incident. On this trajectory the spill path will continue and cross the Trajectory Norway/Denmark median line within 31 hours of the incident. Modelling indicates that towards closest 3 approximately 161,742m3 (emulsified) of crude oil could beach on the Danish coast after 5 international days and 12 hours. It is estimated that approximately 35,166m3 will evaporate and 32,486m3 boundary will disperse naturally within the water column. On this trajectory possible beaching locations are within numerous protected areas along the Danish and Norwegian coastlines (see Figure 8-3). Figures B-4 Modelling indicates that it is unlikely that the spill will beach on the coastline. The leading 4 Stochastic edge of the spill travels 6 miles from the Alma development after 10 hours. This is still 171 miles from shore. It is estimated that 2,086m3 will evaporate and 3,744m3 will disperse naturally in the water column (none will beach).

REPORT REF: P1459BA_RN2525_REV0 B-5 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Scenario Model run type Fate of spill, as modelled

Figures B-5 Modelling indicates that on this trajectory it is unlikely that the spill will beach on the UK Trajectory 5 coastline. The leading edge of the spill travels 6 miles from the Alma development after 10 towards UK hours. This is still 171 miles from shore. It is estimated that 2,086m3 will evaporate and 3,744m3 will disperse naturally in the water column (none will beach). Figures B-6 Trajectory Modelling indicates that on this trajectory it is unlikely that the spill will beach on a coastline. towards closest 6 The leading edge of spill travels 20 miles from the Alma development after 10 hours and will international cross the UK/Norway median line within 6 hours. It is estimated that 2,235m3 will evaporate boundary and 3,595m3 will disperse naturally (none will beach).

REPORT REF: P1459BA_RN2525_REV0 B-6 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Figure B-2- Scenario 1-Worst case crude oil spill of 100,000m3 Key for wind rose

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Figure B-3-Scenario 2- Worse case crude oil spill trajectory with 30 knot wind towards the UK

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Figure B-4-Scenario 3- Worse case crude oil spill trajectory with 30 knot wind towards the closest international boundary (and Denmark)

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Figure B-5- Scenario 4- Instantaneous diesel spill of 5,830m3

Key for wind rose

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Figure B-6- Scenario 5- Worst case diesel spill trajectory with 30 knot wind towards the UK

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Figure B-7- Scenario 6- Worst case diesel spill trajectory with 30 knot wind towards the closest international boundary

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B.5 Environmental Impact Assessment

B.5.1 Seabirds

A diesel spill will rapidly evaporate on release and will naturally disperse in the high energy offshore environment. Modelling, presented in Figures B-4, B-5 and B-6, indicates that a diesel spill of 5,830m3 i.e., from a combined loss of inventory from the FPSO and export tanker, will naturally disperse and evaporate within 10 hours. As such, it is not considered that diesel will pose a significant threat to seabirds. There is the potential that seabirds could be significantly affected if a large crude oil spill was to occur. The worst case scenarios modelled i.e., loss of containment from both the FPSO and export tanker due to collision, has the potential to affect a large area of the marine environment and depending on the prevailing wind condition at the time beach on the coastline of one of the countries bordering the North Sea. These results of the modelling area provided in Table B-2 above. A spill of the magnitude modelled above is likely to significantly impact populations of seabirds. Seabirds that spend majority of the time on sea surface are most vulnerable as birds can be smothered by oil or their feathers can become contaminated with hydrocarbons, which in turn may be ingested. Seabird vulnerability to hydrocarbon pollution is highest in January and October. As the drilling rig will be on-site from December 2011 until January 2013, there will be overlap with the sensitive periods for seabirds. In addition, the FPSO will offload crude oil every two weeks throughout the year and therefore at some point each year operations will overlap with the sensitive periods identified. In the event of a spill occurring, the required intervention response will be implemented to minimise the risk of smothering and species injury.

B.5.2 Marine Mammals

There is the potential that marine mammals could be significantly affected if a large crude oil spill was to occur. Although the region surrounding the Alma development is not considered to be particularly important for marine mammals, pods and individuals have been observed throughout the year. Should a major release of crude oil occur, there is the potential that individuals could be affected. In addition should any oil reach the shoreline, haul-out sites for pinnipeds may be impacted. Pinnipeds are particularly sensitive between October and January when they are on land pupping and again between February and March during their annual moult. Neonatal pups are particularly at risk from oil coming ashore. Cetaceans have smooth hairless skins over a thick layer of insulating blubber, so oil is unlikely to adhere persistently or cause a breakdown in insulation. Marine mammals must surface to breathe and they may inhale vapours given off the spilt oil and their eyes may be vulnerable to major pollution. Indirect effects may also be caused through contamination and depletion of food resources.

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Due to the transient nature of cetaceans, it is likely that individuals not in the immediate area of the spill when it occurs will avoid the area and it is possible that the number of individuals affected could be small. However, if a substantial number of a population where affected there could be knock on effects to breeding and the long-term viability of the population. Recovery rates of land based marine mammals such as seals could be longer particularly if a spill affected a breeding season.

B.5.3 Protected Sites

There is the potential that protected sites and species could be significantly affected if a large crude oil spill was to occur. Although there are no designated protected sites within 40km of the Alma field a major crude oil spill could beach on the coastline as summarised in Table B-2 and Figure B-1. Modelling indicates that the probability of the spill beaching is 1%. There are numerous coastal and marine protected sites designated along the coast of the North Sea that could be affected. These are illustrated in Figure 8-3. Should a spill occur that could potentially affect a protected area an intervention response would be required.

B.6 References

OSR (2011). Oil Spill Modelling for Knightsbridge Field Development. Prepared for Metoc Ltd. Project Number 4558.

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Appendix C Summary of chemicals

REPORT REF: P1459BA_RN2525_REV0 C-1 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Please note: All chemicals provided in the following tables are for one well (five sections) and one well tie-in only. Full chemical requirements will be confirmed in the relevant PON15B or PON15C chemical permit application to be submitted to the DECC at least 28 days before operations start. Chemicals to be used on the FPSO had not been confirmed at the time of ES submission but will be included in a PON15D chemical permit. This will be available for public review approximately 2 months prior to production operations commencing.

C.1 Drilling Chemicals

C.1.1 36" Section

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) Caustic Soda E 0.60 0.60 DEFOAM NS Gold SUB 4.00 4.00 Drispac® Plus Superlo ™ Polymer E PLO 6.39 6.39 DUO-TEC Gold 3.00 3.00 DUO-VIS Gold 3.00 3.00 GUAR GUM E PLO 20.00 20.00 Lime E PLO 1.00 1.00 M-I BAR (All Grades) E PLO 210.00 210.00 M-I Gel E PLO 72.00 72.00 Mica E PLO 2.00 2.00 Nutshells (All Grades) E PLO 2.00 2.00 POLYPAC (All Grades) E PLO 4.10 4.10 SAFE-CIDE Gold 1.10 1.10 SAFE-SCAV HSB Silver 1.00 1.00 Soda Ash E PLO 0.60 0.60 Sodium Bicarbonate E PLO 2.00 2.00

C.1.2 26" Section

REPORT REF: P1459BA_RN2525_REV0 C-2 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) POLYPAC (All Grades) E PLO 4.10 4.10 SAFE-CIDE Gold 1.10 1.10 SAFE-SCAV HSB Silver 1.00 1.00 Soda Ash E PLO 0.60 0.60 Sodium Bicarbonate E PLO 2.00 2.00

C.1.3 17 ½" Section

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) CAUSTIC SODA E 5.40 5.40 Citric Acid E PLO 4.00 4.00 DEFOAM NS Gold SUB 4.00 4.00 DRILLING STARCH E PLO 3.00 3.00 Drispac® Plus Superlo ™ Polymer E PLO 19.17 19.17 DUO-TEC Gold 7.75 7.75 DUO-VIS Gold 4.00 4.00 Dynared ™ Seepage Control Fiber E PLO 8.00 8.00 GLYDRIL MC Gold 20.00 20.00 G-SEAL PLUS E PLO 6.00 6.00 GUAR GUM E PLO 19.00 19.00 KWIK-SEAL (All Grades) E 6.00 6.00 Lime E PLO 1.00 1.00 M-I BAR (All Grades) E PLO 450.00 450.00 M-I GEL E PLO 460.00 460.00 Nutshells (All Grades) E PLO 2.00 2.00 POLYPAC (All Grades) E PLO 8.15 8.15 POTASSIUM CHLORIDE E PLO 6.00 6.00 Potassium Chloride brine E PLO 20.00 20.00 SAFE-CARB (All Grades) E PLO 15.00 15.00 SAFE-CIDE Gold 1.10 1.10 SAFE-SCAV HSB Silver 1.00 1.00 SAPP E PLO 2.00 2.00 SODA ASH E PLO 5.40 5.40 Sodium Bicarbonate E PLO 4.00 4.00

REPORT REF: P1459BA_RN2525_REV0 C-3 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

C.1.4 12 ¼" Section

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) BENTONE 920 E 18.86 0.00 Calcium Chloride (All Grades) E PLO 24.36 0.00 CAUSTIC SODA E 1.00 0.00 Citric Acid E PLO 4.00 0.00 DF1 E 500.39 0.00 DUO-TEC Gold 3.00 0.00 DUO-VIS Gold 3.00 0.00 Dynared ™ Seepage Control Fiber E PLO 6.00 0.00 ECOTROL RD E SUB 11.07 0.00 EMI-1017 C 18.15 0.00 FORM-A-SQUEEZE E PLO 8.00 0.00 G-Seal E PLO 16.00 0.00 G-SEAL PLUS E PLO 16.00 0.00 KOPLUS LO Gold 8.00 0.00 KWIK-SEAL (All Grades) E 6.00 0.00 LIME E PLO 28.00 0.00 M-I BAR (All Grades) E PLO 646.60 0.00 Mica E PLO 6.00 0.00 NUTSHELLS (All Grades) E PLO 6.00 0.00 Potassium Chloride E PLO 5.00 0.00 SAFECARB (All Grades) E PLO 50.00 0.00 SAFES-CAV HSB Gold 1.00 0.00 SAFE-SURF E Gold SUB 4.00 0.00 SAFE-SURF NS Gold SUB 6.00 0.00 SAPP E PLO 2.00 0.00 Sodium Bicarbonate E PLO 4.00 0.00 SPERSENE CFI E PLO 5.00 0.00 SUPER SWEEP Gold SUB 1.00 0.00 SWA EH A SUB 4.00 0.00 TRUVIS E 17.34 0.00 Ven-chem 222 E 16.00 0.00 VERSACLEAN CBE B SUB 18.00 0.00 Versaclean FL B SUB 18.00 0.00 Versaclean VB B SUB 18.00 0.00 VERSAGEL HT E 30.00 0.00 VERSATROL E SUB 17.58 0.00 VERSATROL HT D SUB 16.00 0.00 VERSATROL M E SUB 9.00 0.00 VG-SUPREME E 18.09 0.00

REPORT REF: P1459BA_RN2525_REV0 C-4 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

C.1.5 8 ½" Section

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) BENTONE 920 E 18.86 0.00 Calcium Chloride (All Grades) E PLO 26.74 0.00 CAUSTIC SODA E 1.00 0.00 Citric Acid E PLO 4.00 0.00 DF1 E 818.27 0.00 DUO-TEC Gold 3.00 0.00 DUO-VIS Gold 3.00 0.00 Dynared ™ Seepage Control Fiber E PLO 6.00 0.00 ECOTROL RD E SUB 16.88 0.00 EMI-1017 C 30.92 0.00 FORM-A-SQUEEZE E PLO 8.00 0.00 G-Seal E PLO 16.00 0.00 G-SEAL PLUS E PLO 16.00 0.00 KOPLUS LO Gold 8.00 0.00 KWIK-SEAL (All Grades) E 6.00 0.00 Lime E PLO 27.00 0.00 M-I BAR (All Grades) E PLO 906.45 0.00 Mica E PLO 6.00 0.00 NUTSHELLS (All Grades) E PLO 6.00 0.00 Potassium Chloride E PLO 5.00 0.00 SAFECARB (All Grades) E PLO 80.00 0.00 SAFE-SCAV HSB Gold 1.00 0.00 SAFE-SURF E Gold SUB 4.00 0.00 SAFE-SURF NS Gold SUB 6.00 0.00 SAPP E PLO 2.00 0.00 Sodium Bicarbonate E PLO 4.00 0.00 SPERSENE CFI E PLO 5.00 0.00 SWA EH A SUB 4.00 0.00 TRUVIS E 21.06 0.00 Ven-chem 222 E 16.00 0.00 VERSACLEAN CBE B SUB 22.00 0.00 Versaclean FL B SUB 20.20 0.00 Versaclean VB B SUB 20.20 0.00 VERSAGEL HT E 26.58 0.00 VERSATROL E SUB 15.86 0.00 VERSATROL HT D SUB 25.50 0.00 VERSATROL M E SUB 21.50 0.00 VG-SUPREME E 21.56 0.00

REPORT REF: P1459BA_RN2525_REV0 C-5 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

C.2 Cementing Chemicals

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) Barite E PLO 408.16 40.816 Calcium Chloride - Liquid E PLO 15.42 1.542 CEMENT - CLASS G E PLO 948 94.8 CFR-8L Gold 8.52 0.852 ECONOLITE LIQUID E PLO 30.67 3.067 Fluorodye UC Gold 0.12 0.012 GASSTOP LIQUID Gold SUB 8.68 0.868 HALAD-300L NS Gold 22.24 2.224 HR-25L Gold 4.67 0.467 HR-4L E PLO 14.12 1.412 HR-601L NS E PLO 4.61 0.461 MUSOL SOLVENT Gold 11.04 1.104 NF-6 Gold 0.84 0.084 SA-533 Gold SUB 2.04 0.204 SCR-100L Gold 10.71 1.071 SCR-500 L Gold SUB 15.51 1.551 SEM 8 Gold 25.38 2.538 SILICALITE LIQUID E PLO 46.08 4.608 SSA-1 E PLO 333 33.3 TUNED LIGHT XL E 240 24 TUNED SPACER E+ E PLO 20.4 2.04 WellLife 734 E PLO 1.36 0.136

C.3 Completion and Other Chemicals

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) Aqueous Degreaser 2000 Gold SUB 12.00 12.00 Bestolife 2010 NM ULTRA (version 1) C O-VII SUB 1.50 0.15 Bestolife 3010 ULTRA (version 1) E 2.20 0.22 Calcium Bromide Brine E PLO 2437.96 2437.96 Calcium Chloride Brine E PLO 1991.58 1991.58 Caustic Soda E 2.00 2.00 Celatom Diatomite-All FW Grades E PLO 3.41 0.00 Celatom Perlite-All Grades E 0.29 0.00 Cesium Formate Brine (unbuffered) Gold 12.50 12.50 CLEENOL OD HEAVY DUTY Gold 34.00 34.00 DEFOAM NS Gold SUB 0.40 0.40 DF1 E 763.14 0.00 DI BALANCE E PLO 2.00 0.00

REPORT REF: P1459BA_RN2525_REV0 C-6 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (tonnes) (tonnes) DI TROL E PLO 4.00 0.00 DUAL-FLO Gold 2.00 2.00 DUO-TEC Gold 4.00 4.00 DUO-VIS Gold 4.00 4.00 EB-8035 Gold SUB 2.00 2.00 EMI-1705 C 1.00 0.00 EMR-961 Silver SUB 10.00 0.00 EZEFLO* Surfactant B197 Gold SUB 1.00 1.00 FLO-VIS PLUS Gold 1.00 1.00 HEC E PLO 2.00 2.00 JET-LUBE® API-MODIFIED C Cu Pb Zn SUB 0.80 0.08 JET-LUBE® NCS-30™ ECF E 3.00 0.30 JET-LUBE®SEAL-GUARD™ECF E 0.50 0.05 MAGNESIUM OXIDE E PLO 1.00 1.00 M-I BAR (All Grades) E PLO 300.00 300.00 Monoethylene Glycol E PLO 10.00 10.00 Potassium Formate Brine E PLO 115.40 115.40 SAFE COR 220X Gold 16.00 16.00 SAFE-CARB (ALL GRADES) E PLO 12.00 12.00 SAFE-CIDE Gold 2.00 2.00 Safe-Cor HT C 0.82 0.82 SAFE-SCAV CA Gold 8.00 8.00 SAFE-SCAV HSB Silver 2.00 2.00 SAFE-SCAV NA E PLO 8.00 8.00 SAFE-SURF E Gold SUB 8.00 8.00 SAFE-SURF NS Gold SUB 18.00 18.00 SI-414N Gold 3.00 3.00 Sodium Chloride Brine E PLO 1991.58 1991.58 Stack-Magic ECO-F v2 D 12.00 12.00 System Cleaner G D 0.04 0.04

REPORT REF: P1459BA_RN2525_REV0 C-7 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

C.4 Pipeline Chemicals

Chemical Name HQ Chemical Estimated Use Estimated Discharge Label (kgs) (kgs) Castrol Transaqua HT2 D 0 101.6 DYESTICK RX-9034A Gold 0.4 0.25 MEG E PLO 445.2 1227.2 RX-9022 Gold 23.6 17.8 RX-5227 Gold 103.4 81.4

Note: Chemical discharge exceeds chemical use as some sections of spool piece or chemical umbilical are pre-filled onshore.

REPORT REF: P1459BA_RN2525_REV0 C-8 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT=

Appendix D JNCC Risk Assessment Flow Charts

REPORT REF: P1459BA_RN2525_REV0 D-1 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Figure D-1: Risk assessment flow chart for deliberate injury

Source: JNCC (2009)

Figure D-2: Risk assessment flow chart for non-trivial disturbance

Source: JNCC (2009)

REPORT REF: P1459BA_RN2525_REV0 D-2 21/07/2011 ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

Figure D-3: M-weighting functions for low-, mid-, and high-frequency cetaceans

Source: Southall et al. (2007)

REPORT REF: P1459BA_RN2525_REV0 D-3 21/07/2011