ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

ENVIRONMENTAL STATEMENT 

BARDOLINO DEVELOPMENT 

Shell Document No: 

BARD-14-SH-0001 

DTI Reference No: W/3999/2008 

This document is the property of Shell U.K. Limited, and the copyright therein is vested in 

Shell U.K. Limited. All Rights Reserved. Neither the whole nor any part of this document 

may be disclosed to others or reproduced, stored in a retrieval system, or transmitted in 

any form by any means (electronic, mechanical, reprographic recording or otherwise) 

without prior written consent of the copyright owner.

Bardolino Development Environmental Statement 

STANDARD INFORMATION SHEET 

Project Name: Bardolino Development 

Project Reference number: W/3999/2008 

Type of Project: Field Development 

Undertaker name: Shell U.K. Limited 

Undertaker address: 

1 Altens Farm Road 

Nigg 

Aberdeen 

AB12 3FY 

Licensees/Owners: Shell U.K. Limited 62% 

OMV U.K. Limited 38% 

Short description: 

Anticipated commencement of 

works: 

Date and reference number of any 

earlier Statement related to this 

project: 

Significant environmental impacts 

identified: 

This Environmental Statement presents the 

findings of an environmental assessment of the 

proposed development of the Bardolino oil and gas 

field. The proposed development involves the 

drilling and commissioning of one well and the 

installation and commissioning of a 2 km 6” 

production pipeline, 3” piggyback gas lift line and 

separate umbilical from a new production manifold 

at Bardolino to the existing Howe subsea manifold. 

Produced reservoir fluids will be transported to 

Nelson via the existing Howe-Nelson pipeline for 

separation, with produced oil subsequently 

transmitted to the BP Unity platform and onwards 

to Cruden Bay, and produced gas to St Fergus via 

the Fulmar gas line. 

Q1/Q2 2009 

None 

Statement prepared by: Shell U.K. Limited 

No significant impacts identified after the 

implementation of appropriate mitigation 

measures. 

April 2008


April 2008 

Standard Information Sheet 

Contents 

Abbreviations 

CONTENTS 

NON TECHNICAL SUMMARY i 

Introduction i 

Project Summary ii 

Environmental Management ii 

Environmental Sensitivities ii 

Evaluation of Potential Environmental Impacts v 

Assessment of Potentially Significant Environmental Impacts v 

Mitigation Measures viii 

Conclusion ix 

1 INTRODUCTION 1-1 

1.1 Project Location 1-1 

1.2 Project Background and Commercial Context 1-1 

1.3 Purpose of the Environmental Statement 1-3 

1.4 Scope of the Environmental Statement 1-3 

1.5 Legislation and Compliance 1-4 

1.6 Consultation 1-4 

1.7 Areas of Uncertainty 1-5 

1.8 Format of the Statement 1-6 

2 ENVIRONMENTAL MANAGEMENT 2-1 

2.1 Policy 2-1 

2.2 HSE Plan 2-1 

2.3 Planning 2-1 

2.4 Implementation and Operation 2-2 

2.5 Checking and Corrective Action 2-2 

2.6 Management Review 2-3


3 PROJECT DESCRIPTION 3-1 

3.1 Introduction 3-1 

3.2 Alternative Concepts for Field Development 3-1 

3.3 Overview of Proposed Project and Schedule 3-4 

3.4 Well Engineering 3-7 

3.5 Installation and Commissioning of Subsea Infrastructure 3-15 

3.6 Modifications and Commissioning of Existing Facilities 3-22 

3.7 Production, Utility and Maintenance Operations 3-24 

3.8 Well Abandonment and Decommissioning 3-27 

4 ENVIRONMENTAL DESCRIPTION 4-1 


4.2 Offshore Physical and Chemical Environment 4-1 

4.3 Offshore Conservation Areas 4-11 

4.4 Offshore Biological Environment 4-18 

4.5 Socio-Economic Environment 4-31 

4.6 Summary and Seasonal Environmental Sensitivities 4-38 

5 EVALUATION OF POTENTIAL ENVIRONMENTAL IMPACTS 5-1 


5.2 Identification of Potential Environmental Impacts 5-1 

5.3 Assessment of Impacts 5-4 

5.4 Significant Impacts Assessment Results 5-19 

6 ASSESSMENT OF POTENTIALLY SIGNIFICANT IMPACTS 6-1 


6.2 The Physical Presence of the Drilling Rig and Support 

Vessels (Including Anchoring of the Drilling Rig) 6-2 

6.3 Discharge of Water-based Mud and Cuttings from the 

Development Well 6-5 

6.4 Atmospheric Emissions from the Bardolino Development 6-9 

6.5 Localised Disturbance to the Seabed from Pipeline Installation, Rock 

Dump Stabilisation and Mattressing 6-13 

6.6 Installation and Physical Presence of the Subsea Structures 6-17 

6.7 Noise Arising during Installation Activities 6-19 

6.8 Increased Produced Water Discharges from Nelson 6-33 

6.9 Accidental Spillage of Hydrocarbons 6-35 

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7 CONCLUSIONS 7-1 

April 2008 

7.1 Project Overview 7-1 

7.2 Local Environment 7-1 

7.3 Potential Impacts 7-1 

7.4 Mitigation Measures 7-4 

7.5 Conclusions 7-7 

8 REFERENCES 8-1 

Appendix 1: Relevant Environmental Legislation 

Appendix 2: Shell U.K. Limited Health, Safety and Environmental Policy 

Appendix 3: Consultation Letter 

Appendix 4: Shell piling procedure


ABBREVIATIONS 

Abbreviation Full Meaning 

Al Aluminium 

AHTV Anchor Handling Tug Vessel 

Ba Barium 

bbls barrels 

bbls/MMscf Barrels per million standard cubic feet 

bcf billion cubic feet 

BERR Department for Business, Enterprise and Regulatory Reform 

BGS British Geological Survey 

BMT British Maritime Technology Limited 

BOP Blow out preventer 

Cd Cadmium 

CEFAS Centre for Environment, Fisheries and Aquaculture Science 

CH4 

Methane 

CHARM Chemical Hazard Assessment and Risk Management 

CI Corrosion Inhibitor 

CITHP Closed In Tubing Head Pressure 

CMS Corporate Management System 

CO Carbon monoxide 

CO2 

Carbon dioxide 

CPA Closest Point of Approach 

CPR Continuous Plankton Recorder 

CRA Corrosion Resistant Alloy 

cSAC candidate Special Area of Conservation 

Cu copper 

dB Decibels 

Defra Department of Environment, Food and Rural Affairs 

DP Dynamic Positioning 

dSAC draft Special Area of Conservation 

DTI Department of Trade and Industry 

DWR Deep Water Route 

dwt Dead weight ton 

EA Environmental Assessment 

EC European Community 

EEC European Economic Community 

EEMS Environmental Emissions Monitoring System 

EIA Environmental Impact Assessment 

EMS Environmental Management System 

E & P Exploration & Production 

EPE Exploration and Production Europe 

EPS European Protected Species 

ES Environmental Statement 

ESD Emergency Shut Down 

EU European Union 

EWT Extended Well Test 

Fe Iron 

FEPA Food and Environment Protection Act 

April 2008



FRS Fisheries Research Services 

GBR Great Britain 

GOR Gas Oil Ratio 

HAB Harmful Algal Blooms 

HAZID Hazard Identification 

HC Hydrocarbons 

Hg Mercury 

HLV Heavy Lift Vessel 

HQ Hazard Quotient 

HSE Health, Safety & Environment 

Hz Hertz 

ICES International Council for the Exploration of the Sea 

ISO International Standards Organisation 

IWC International Whaling Commission 

JNCC Joint Nature Conservation Committee 

KCl Potassium chloride 

kg Kilogramme 

km Kilometre 

km 2 Square kilometre 

kW Kilo watt 

LAT Lowest Astronomical Tide 

LTOBM Low Toxicity Oil Based Mud 

m Metres 

MARPOL 

April 2008 

International Convention for the Prevention of Pollution from Ships, 1973, as modified by the 

Protocol of 1978 relating thereto 

MMm 3 /day Million cubic metres per day 

MMscf Million standard cubic feet 

MMscf/d Million standard cubic feet per day 

m/s Metres per second 

MCA Maritime and Coastguard Agency 

MDAC Methane Derived Authigenic Carbonate 

MES Minimum Environmental Standards 

MEG Mono-ethylene glycol 

MSL Mean Sea Level 

MW megawatt 

NaCl Sodium chloride 

NAQS National air quality standards 

NFFO National Federation of Fishermen’s Organisations 

ng/l Nanograms per litre 

Ni Nickel 

nm Nautical mile 

N2O Nitrous oxide 

NOx 

Nitrogen oxides 

NSTF North Sea Task Force 

OCNS Offshore Chemicals Notification Scheme 

OCR Offshore Chemical Regulations 

OPPC Oil Pollution Prevention and Control 

OPRC International Convention on Oil Pollution Preparedness, Response and Co-operation 

OSCP Oil Spill Contingency Plan



OSPAR Oslo and Paris Commission 

OSIS Oil Spill Information System software 

OVI Offshore Vulnerability Index 

PAH Polycyclic Aromatic Hydrocarbons 

Pb lead 

PCB Poly Chlorinated Biphenyls 

PLONOR Posing Little or No Risk to the Environment 

PON Petroleum Operations Notice 

POPA Prevention of Oil Pollution Act 

ppm Parts per million 

ppt Parts per thousand 

pSAC possible Special Area of Conservation 

ROV Remotely Operated Vehicle 

RSPB Royal Society for the Protection of Birds 

SAC Special Area of Conservation 

SAHFOS Sir Alister Hardy Foundation for Ocean Science 

SAST Seabirds at Sea Team 

SCANS [Survey of] Small Cetaceans Abundance of the North Sea (and Adjacent Waters) 

scf Standard cubic feet 

SCI Sites of Community Importance 

SD Sustainable Development 

SEA Strategic Environmental Assessment 

SEERAD Scottish Executive Environment and Rural Affairs Department 

SL Source level 

SMRU Sea Mammal Research Unit 

SO2 

Sulphur dioxide 

SPL Sound Pressure Levels 

SSB Spawning Stock Biomass 

t tonnes 

THC Total Hydrocarbon Concentration 

TTS Temporary threshold shift 

TSS Traffic Separation Scheme 

UK United Kingdom 

UKCS United Kingdom Continental Shelf 

UKDMAP United Kingdom Digital Map 

UKOOA United Kingdom Offshore Operators Association 

UKOPP United Kingdom Oil Pollution Prevention 

VOC Volatile Organic Compounds 

WBM Water Based Mud 

WWF World Wildlife Fund 

Zn Zinc 

µg/g Micrograms per gram 

µg/l Micrograms per litre 

µg/m 3 Microgram per cubic metre 

April 2008


April 2008 

This Page is Intentionally Blank


NON-TECHNICAL SUMMARY 

INTRODUCTION 

The proposed Bardolino Development is located in Blocks 22/11, 22/12 and 22/13 of the United 

Kingdom Continental Shelf (UKCS) in the central North Sea. The field lies approximately 190 km 

east of Peterhead and 40 km west of the UK/Netherlands median line (Figure i). 

This Environmental Statement (ES) presents the findings of Shell’s assessment of the 

environmental consequences of the development of the Bardolino Field. The submission of this 

ES is required under the Offshore Petroleum Production and Pipelines (Assessment of 

Environmental Effects) Regulations 1999 (as amended). 

Before the ES was submitted for both public consultation and review by the Department of 

Business, Environment and Regulatory Reform (BERR), potential stakeholders that may have an 

interest in the operations, namely, fisheries organisations and conservation groups, were 

identified and contacted. During the course of this assessment, Shell has consulted on the scope 

of the ES with representatives of BERR, the Joint Nature Conservation Committee (JNCC), the 

Fisheries Research Service (FRS), the Scottish Fishermen’s Federation (SFF), the Marine 

Conservation Society, Aberdeen Coastguard Offshore Oil & Gas Team, Defence Estates, Royal 

Society for the Protection of Birds (RSPB), the Coastguard Agency Marine Pollution Control Unit 

(MPCU) and the Scottish Government Marine Directorate. 

Figure i: Location of the Bardolino Development 

April 2008 Page i


PROJECT SUMMARY 

Several options for developing the Bardolino field have been assessed in order to determine the 

most favourable option, taking into account the economic, technical, commercial, safety and 

environmental challenges of the project. The development that is now proposed comprises the 

drilling of a single development well tied back via a new manifold and 2 km long 6” production 

pipeline, with piggy-backed 3” gas lift line, to the Howe sub-sea manifold, which itself is tied-back 

to the Nelson platform. A separate electro-hydraulic and chemical control umbilical will also be 

installed between Bardolino and Howe. 

The assessment includes the effects, on all relevant components of the offshore environment, of 

planned activities associated with the proposed Bardolino development. Project activities include: 

• Well Engineering Activities: The drilling of a single development well and connection to 

a new production manifold. 

• Installation and Commissioning: Installation and commissioning of a 2 km, 6" 

production pipeline to the Howe subsea infrastructure with 3" gas lift pipeline and electrohydraulic 

and chemical control umbilical. Installation and commissioning of a new 

manifold at Bardolino and new valve skid at Howe. 

• Production, Utility and Maintenance Operations: Operation of the Bardolino facilities, 

including the handling of produced fluids at Nelson and the use and possible discharge of 

chemicals. 

• Decommissioning: This will not be addressed in this ES – a separate environmental 

assessment will be undertaken at the appropriate time (see Section 3.8). 

Project activities are scheduled to commence in Q1/Q2 2009 with production estimated to begin 

in August 2009. 

ENVIRONMENTAL MANAGEMENT 

Shell has a formal documented Corporate Management System (CMS) that is designed to 

implement the Company’s Health, Safety and Environmental (HSE) policy. Shell UK’s 

Environmental Management System (EMS) is embedded in the CMS and the EMS is certified to 

the International Standards Organisation (ISO) Standard 14001 for Environmental Management 

Systems (EMS). The CMS requires a commitment to compliance with legislation and continual 

improvement in environmental performance, and applies to all elements of the Bardolino 

development. 

ENVIRONMENTAL SENSITIVITIES 

The proposed development is located in an area that is typical of the offshore regions in the 

central North Sea, where hydrographical, meteorological, geological and biological characteristics 

are relatively uniform over large areas. Users of the area are mainly those associated with oil 

and gas exploration and development, shipping and fishing. Table i provides a summary of the 

key features of the offshore environment in this area, and their seasonal patterns of activity or 

sensitivity. 

April 2008 Page ii


Table i: Summary of seasonal environmental sensitivities for the proposed Bardolino 

Development Area 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Habitats Directive: Annex I Habitats 

There are no known Annex I Habitats in the vicinity of the proposed development area. The site does not lie within an area 

of gas seep and no pockmarks were identified during surveys at the proposed rig site and pipeline route. 

Currently, the closest possible SAC to the area is the Scanner Pockmark which is approximately 67 km from the Bardolino 

development. 

Habitats Directive: Annex II Species 

The harbour porpoise is the only Annex II species to be sighted within the vicinity of the proposed development area. 

Sightings have been recorded in the proposed development area during June and July, although porpoise may be present in 

the area throughout the year. 

Harbour porpoises are potentially vulnerable to noise, contaminants, oil spills and any effects on prey availability associated 

with the proposed development. The UK currently has no proposed SACs for harbour porpoises. 

Plankton 

Plankton is vulnerable to oil and chemical discharges. Planktonic organisms constitute a major food resource for many 

commercial fish species, benthic species and marine mammals, so any changes in their abundance, distribution and 

composition are important. There is also the possible bioaccumulation of pollutants ingested by plankton. Plankton is widely 

distributed over the North Sea and peak plankton productivity generally occurs in spring and summer. 

Benthic fauna 

Benthic fauna are vulnerable to disturbance of the seabed sediments which form their habitats, for example during the 

installation of pipelines and subsea structures, the anchoring of drilling rigs or vessels, and the discharge of drill cuttings. 

The effects of discharged cuttings on benthic fauna include physical smothering, the presence of potential toxins (heavy 

metals and hydrocarbons), and organic enrichment. Benthic fauna are an important food resource to demersal fish and 

shellfish. Benthic communities in the development area are similar to those found throughout the surrounding area of the 

central North Sea and no rare species are known to occur in this area. 

Finfish and Shellfish Populations 

Finfish and shellfish are vulnerable to pollution, such as oil and chemical discharges, the impact of drill cuttings, and the 

potential effects of seismic surveys, especially during the egg, larval and juvenile stages of their lifecycle. Demersally- 

spawning species and fish/shellfish that live in close association with seabed sediments are particularly vulnerable to any 

sediment disruption, for example during the installation of subsea structures, the anchoring of drilling rigs or vessels, and the 

discharge of drill cuttings. 

The proposed development area lies within spawning grounds for mackerel (May to Aug.), lemon sole (Apr. to Sep.), Norway 

pout (Jan. to Apr.) and Nephrops (Jan. to Dec., peak period is between Apr. and Jun.) and coincides with nursery grounds 

for haddock, Norway pout, blue whiting and Nephrops. Fish species present in the proposed development area are 

generally distributed throughout the North Sea. 

April 2008 Page iii



Cetaceans 

Several marine mammal species are present throughout the North Sea throughout the year. Killer and minke whales, white- 

beaked and white-sided dolphins, and harbour porpoises are widely distributed in the northern-central North Sea and may 

occur regularly in the vicinity of the proposed development. Long-finned pilot and sperm whales, and common, striped, 

Risso’s and bottlenose dolphins may also be seen occasionally within the area. The occurrence of most cetacean species is 

generally higher during summer months. Cetacean species present in the proposed development area are generally 

distributed throughout the North Sea. 

Marine mammals can be impacted by noise, contaminants and discharges, oil spills, collisions with vessels and any effects 

on prey availability associated with oil and gas activities. Potential sources of acoustic disturbance from underwater noise 

generated during the proposed development include DP vessels, standby vessels and noise associated with the installation 

of the pipeline and associated sub-sea structures, including in particular noise from piling operations. 

Seabirds 

Seabirds are vulnerable to oiling from surface oil pollution, which can cause direct toxicity through ingestion, and 

hypothermia as a result of the birds’ inability to waterproof their feathers. Certain birds, including guillemots, razorbills and 

puffins, are more vulnerable to oil spills in the moulting season, when they become flightless and spend a large amount of 

time on the water surface. 

Species commonly found in the offshore waters such as the proposed development area include fulmar, gannet, guillemot, 

razorbill, and kittiwake, and herring, great black-backed and lesser black-backed gull. In the proposed development area, 

the most sensitive time of the year is between July and November when seabird vulnerability to oil pollution is “high”. 

Vulnerability ranges from “moderate” to “low” for the remainder of the year, and the overall seabird vulnerability to surface 

pollution in the area is “moderate”. 

Commercial Fishing Activity 

The relative value of fishing in the area of the proposed development is “low”. Demersal, pelagic and crustacean species 

are caught in the area. The predominant species of fish landed in the proposed development area (ICES 44F1 and 43F1), 

were demersal species. 

The proposed development has the potential to interfere with fishing activities, for example as a result of exclusion zones. 

There is also the potential risk of the accidental snagging of fish nets on sub-sea structures associated with development. 

Shipping Activity 

Shipping traffic comprises 12 routes which pass within 10 nm of the proposed development with approximately 624 vessels 

per year (equivalent to 1 to 2 vessels per day). Any shipping traffic in the area will consist mainly of fishing vessels, 

merchant vessels and offshore industry vessels. 

Key to Level of Sensitivity / Activity 

Very high 

High 

Moderate 

Low 

April 2008 Page iv


EVALUATION OF POTENTIAL ENVIRONMENTAL IMPACTS 

The proposed development has the potential to affect the environment in different ways. This 

may include physical disturbance of the seabed, and the creation of gaseous emissions, aqueous 

discharges and solid wastes throughout the life of the project. An evaluation of the relative 

significance of these potential environmental effects has been undertaken for each of the 

activities associated with the Bardolino development, so that any potentially significant impacts 

can be assessed and mitigated. The evaluation took account of the activity causing the impact or 

risk associated with the main project activities, the sensitivity of the location, and the time of year 

the activity is taking place. The possible effects of non-routine and potential 

accidental/emergency events were also considered. 

The evaluation utilised predefined significance criteria with seven levels of impact: severe, major, 

moderate, minor, negligible, none and beneficial. All of the possible releases and disturbances 

were determined to be of potentially minor or negligible environmental significance. The most 

significant areas of potential environmental impact, defined as those classified as being of 

moderate or greater significance, were then assessed in greater detail. Attention has focussed 

on reducing these impacts. 

ASSESSMENT OF POTENTIALLY SIGNIFICANT ENVIRONMENTAL IMPACTS 

This assessment identified the following seven potential impacts as being of greatest significance 

to the environment: 

• the physical presence of the drilling and support vessels (including anchoring of the 

drilling rig); 

• the discharge of water-based mud and cuttings from the development well; 

• the atmospheric emissions that would arise from the installation of the Bardolino 

development infrastructure; 

• the local disturbance to the seabed caused by pipeline trenching and backfilling, rock 

dump stabilisation and mattressing; 

• the installation and physical presence of the subsea structures (manifold, tree and valve 

skid); 

• the underwater noise that would be created during the operations to install the Bardolino 

facilities; 

• the discharge of produced water at the Nelson platform; and 

• any accidental hydrocarbon spillage or release. 

The physical presence of the drilling and support vessels (including anchoring) 

A semi-submersible drilling rig would be used to drill the Bardolino development well. The drilling 

rig would be moored on location by 8 anchors, in a pre-determined ‘anchor pattern’. The use of 

anchors to position and moor the drilling rig would result in the physical disturbance of the seabed 

sediments and bottom-dwelling fauna in localised areas around the anchors (chains and wires) 

during their deployment and retrieval. 

Depending on the nature of the seabed, anchors can create mounds on the seabed up to 1m 

high, while anchor chains lying on, and sweeping over, the sediments can create gouges and 

scour marks. Anchor mounds can form on clayey sediments, and because of the stiffness of clay 

they have the potential to become long-lived seabed features that may represent obstructions to 

mobile fishing gear deployed on the seabed. Surveys have shown that the seabed in the 

Bardolino area comprises fine sandy sediments, with occasional exposures of the underlying 

clay. 

April 2008 Page v


The deployment and retrieval of anchors from the drilling rig would cause localised temporary 

disturbance to the seabed over an estimated total area of 1 km 2 . The anchoring operations would 

all be within UK waters, so there would be no trans-boundary impacts. The anchor pattern that 

would be used, and the placement and removal of the anchors, would be carefully planned. 

For other users of the sea, access around the drilling rig would be restricted for the period during 

which drilling will take place. All the anchors would be completely removed from the seabed at 

the end of the drilling programme before the rig departs. The impact of anchoring the drilling rig 

is therefore considered to be insignificant. 

The discharge of water-based mud and cuttings from the development well 

Water-based mud will be used during the riserless drilling of the top two sections of development 

well, and cuttings from these sections will be discharged directly onto the seabed at the well site.. 

The cuttings deposited on the seabed may have a short term smothering effect on fauna living on 

the seabed, and the fish spawning grounds, in the immediate vicinity of the well location. 

Recovery of the habitat would be enhanced by the dispersion, dilution and breakdown of the 

chemicals within the cuttings which would be brought about by the existing metocean current 

regime. Spreading and natural dispersion of the cuttings would occur as a result of sediment 

movement in the area. Bioturbation, caused by the action of burrowing seabed-dwelling 

organisms, would also aid this process. These effects would minimise any smothering that might 

occur in a region where the tidal currents are sufficiently weak to permit the deposition of the 

cuttings. Re-colonisation of the area by seabed-dwelling animals is predicted to occur very 

readily. 

Low toxicity oil-based mud will be used for the remaining four sections of the development well. 

The cuttings derived from these sections will be returned to the drilling rig where they will be 

totally contained, and then returned to shore for treatment and disposal. 

All drilling chemicals or products (including cementing products) require a permit for use and 

discharge offshore and would be subject to a chemical risk assessment prior to drilling, as 

required by the Offshore Chemical Regulations 2002. This would provide Shell with an 

opportunity to consider alternative chemicals where the outcome of the risk assessment is shown 

to be unfavourable. The effect of the proposed drilling discharges is considered to be 

insignificant. 

The atmospheric emissions arising from the Bardolino development 

Flaring of oil and gas to clean-up the development well would release combustion gases into the 

atmosphere. These have the potential to contribute to global / regional atmospheric effects such 

as global warming and photochemical pollutant formation. The clean-up operation would be 

limited to a total testing and clean-up period of 48 hours, with a maximum of 15,000 bbls (1,900 

tonnes) of oil (with an expected GOR of 870 scf/bbl) flared. 

Well clean-up procedures would be in place to ensure that the operation is carried out as 

efficiently as possible. High-efficiency flare burners will be used, and they will be operated to 

ensure they were working as efficiently as possible, in order to minimise emissions. 

The consumption of diesel fuel for vessel operations associated with drilling the development, 

installing the pipelines and umbilical, and installing the structures on the seabed, would result in 

the generation of carbon dioxide and other exhaust gases. 

From a global perspective, the levels of the emissions from the Bardolino development represent 

a very small proportion of total emissions arising from all UK offshore well-testing and production 

activities, and will make a negligible contribution to global / regional levels of CO2 and other 

gases. 

April 2008 Page vi


Localised disturbance to the seabed from the installation and mattressing of the pipeline 

A 2 km gas export pipeline (piggybacked by a 3” chemical pipeline), and a separate umbilical, 

would be laid between the Bardolino well and the existing Howe manifold. The pipelines and 

umbilical would be laid in two separate trenches. The trenching of the pipelines and umbilical has 

the potential to impact the seabed sediment and organisms living within it. 

The trenching operations would disturb the seabed along a 6 m wide corridor at the top of a deep 

‘vee’-shaped trench. A narrow, 2 m wide band of seabed on either side of each trench would be 

affected by the deposition of soil excavated from the trenches, and it is estimated that a total area 

of 0.02 km 2 of seabed would be temporarily impacted by the trenching operations. 

There are no proposed or designated conservation sites in the immediate vicinity of the Bardolino 

development. Access along the pipeline route for other users of the sea would be restricted for 

the period during which installation will take place, estimated to be about 6 weeks. 

The potential impact of the installation and presence of the pipeline is therefore considered to be 


Installation and physical presence of the subsea structures 

The installation of a new production manifold, a production tree and a valve skid would result in 

highly localised physical disturbance of the seabed sediments and associated fauna. This would 

result in loss of habitat in the area directly below the subsea structures, with consequent impact 

on the seabed-dwelling organisms. 

The subsea structures are located in an area of low commercial value for all fish species caught 

by UK fishermen in comparison to all areas fished around the UK. The main fishing gears used in 

the area are demersal / bottom trawling methods which have the greatest potential to interact with 

subsea structures. 

The subsea structures would be enclosed within protective tubular steel frames, which are 

designed to have a fishing-friendly profile. No significant operational problems for demersal 

trawling are foreseen from the presence of the protected structures on the seabed. 

Underwater noise that would arise from the Bardolino development 

Underwater noise would be generated by the activities associated with the Bardolino 

development. The main source of underwater noise would be from piling two subsea structures 

to the seabed. The duration of the piling activities would be approximately 12 hours per structure, 

and there would be a gap between the two operations. Marine mammals could be impacted by 

noise during these operations; they may take avoidance action if they are disturbed, but evidence 

indicates that they would return once activities have ceased. Densities of cetaceans in the area 

are low compared to other areas of the North Sea. 

Noise levels from these activities are unlikely to cause anything more than a temporary local 

disturbance to marine mammals. Shell will ensure that piling will only begin during daylight hours. 

A qualified and experienced marine mammal observer (MMO) would be present on the standby 

vessel throughout the operations, to monitor the presence of marine mammals in the area. Piling 

would only begin when it was confirmed that marine mammals were not present in a pre-defined 

area close to the piling site. A “soft start” would be undertaken for each new period of piling, so 

as to alert marine mammals in the area and give them the opportunity to move away. 

Discharge of produced water at the Nelson platform 

The Bardolino development will result in an increase in the quantity of produced water discharged 

at the Nelson platform; the increase is likely to be


The permitted discharge of treated produced water into the marine environment can have an 

impact on water quality and pelagic organisms in a localised area immediately around the 

discharge point. The species comprising the pelagic community at Nelson are widely distributed 

in the water masses that flow over large areas of the North Sea. They are mobile, and so would 

be unlikely to be exposed for a long period of time to the very locally enhanced concentrations of 

oil that might be present at the discharge point. The permitted discharge of treated produced 

water will be rapidly dispersed and diluted in the prevailing metocean conditions. It is therefore 

considered that this discharge would not have any significant effects on pelagic or benthic 

communities. There would be no trans-boundary impacts or significant contribution to global 

impacts. 

The produced water from the Bardolino development would be treated by the existing produced 

water treatment system on the Nelson platform. The concentration of oil in produced water would 

be measured at least twice each day at the host facility, using industry-approved methods, and 

reported accordingly. 

Accidental Hydrocarbon Spillage or Release 

Accidental spills of hydrocarbons are recognised as potentially damaging to the environment. 

Shell will ensure that the mitigation measures in place during all phases of the development will 

reduce the risk of hydrocarbon spills to as low as reasonably practicable. The worst-case spill 

scenario has been identified as the potential spill of 50 m 3 total inventory of Bardolino crude oil 

from the rupture. 

Seabird vulnerability to oil pollution in the area of the proposed development is “high” to “very 

high” in July, September, October and November, with “moderate” to “low” seabird vulnerability 

for the remainder of the year. Modelling has shown that the release of 1,000 tonnes of diesel 

would disperse rapidly and evaporate from the sea surface. Shell has comprehensive 

contingency plans to manage spills and minimise the environmental impact of any such event. 

The mitigation measures and contingency plans in place would consider all foreseeable spill risks 

and would ensure that the spill risk is reduced to as low as reasonably practicable. The 

contingency plans would ensure that an appropriate response is made to any spill in order to 

minimise impact on the environment. 

MITIGATION MEASURES 

Shell is committed to environmental protection in this and all other offshore operations. The 

activities associated with the Bardolino development will be conducted in accordance with Shell’s 

CMS. The procedures that support this management system will put robust environmental 

safeguards in place as detailed in this Environmental Statement. 

A summary of the main commitments in the ES for the Bardolino development are as follows: 

• Waste, including drilling cuttings contaminated with oil based mud, will be segregated 

and shipped to shore for disposal in line with Shell policies and current legislation. 

• The drilling programme will be covered by Shell’s Emergency Procedures and Oil Spill 

Contingency Plan. 

• Shell will issue Notices to mariners to advise shipping and fishing traffic of the 

potential hazards to navigation associated with the Bardolino project. 

• No extended well test is planned, and Shell would ensure all well clean-up procedures 

are in place and maintained to ensure operations are carried out efficiently. 

• Piling activities will be conducted according to Shell’s procedures and guidelines to 

minimise any impacts on marine mammals, which have been agreed with JNCC. 

• All activities will be carried out in line with Shell HSE policy and current legislation. 

April 2008 Page viii


CONCLUSION 

The proposed development of the Bardolino field is not expected to lead to significant 

environmental effects. The proposed development is located in an area which is typical of the 

central North Sea in terms of habitats and marine life. None of the environmental receptors is 

assessed as being particularly sensitive to the type of activity proposed. 

Shell’s CMS applies to all aspects of the proposed project. The activities associated with the 

Bardolino development will be included in the Company’s environmental measurement and 

monitoring programmes, which track performance against corporate targets for important 

emissions and discharges. 

This environmental assessment demonstrates that the drilling of the Bardolino well and the 

installation of the associated development infrastructure structure will have no significant effects 

on environmental resources in the central North Sea. The controls on operations have been 

designed to ensure that robust environmental safeguards will be put in place, and preventative 

measures have been designed to minimise any potential environmental risks. It is concluded that 

the Bardolino development could be implemented without significant adverse effects on the 

environment. 

Shell believes that the measures that will be taken to minimise the environmental effects 

associated with the Bardolino development represent an appropriate balance between protecting 

the environment and securing the economic benefits of the proposed project. 

April 2008 Page ix


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April 2008 Page x


1 INTRODUCTION 

This Environmental Statement (ES) presents the findings of an Environmental Impact 

Assessment (EIA) carried out by Shell U.K. Limited (Shell) for the proposed development of 

the Bardolino Field. The field is jointly owned by Shell (68%) and OMV U.K. Limited (OMV) 

(32%) and will be operated by Shell. 

1.1 PROJECT LOCATION 

The proposed Bardolino Development is located in Block 22/13 of the United Kingdom 

Continental Shelf (UKCS) in the central North Sea, and will be tied-back to Howe in 22/12 and 

then Nelson in 22/11. The Bardolino Field lies approximately 190 km east of Peterhead on 

the Aberdeenshire coast and 40 km west of the UK/Norway median line (Figure 1.1). Water 

depths at the proposed development area are approximately 85 m. 

Figure 1.1: Location of the Bardolino Development 

1.2 PROJECT BACKGROUND AND COMMERCIAL CONTEXT 

The Bardolino field was discovered by discovery well 22/13a-1 drilled in 1988. Two further 

appraisal wells, 22/13a-2 and 22/13a-4, were drilled during 1989. The Bardolino reservoir is 

of Fulmar and Hugin sands with initial gas oil ratio (GOR) expected to be approximately 870 

scf/bbl. Ultimate recovery from Bardolino is estimated to be in the region of 10,million bbls, 

and the expected field life is approximately 11 years. 

April 2008 Page 1-1


The Bardolino field will be developed with as a single well tied-back to the Howe subsea 

manifold. A 2km 6” production pipeline and piggyback 3” gas lift line, and a separate electrohydraulic 

and chemical control umbilical, will be installed between Bardolino and Howe. 

Fluids will be subsequently taken to the Nelson platform via the existing pipeline between 

Howe and Nelson for separation and export (Figure 1.2). Oil is exported from Nelson by 

pipeline to the nearby BP Unity platform and then by the Forties pipeline to the landfall at 

Cruden Bay. Gas is exported via the Fulmar gas pipeline to the St. Fergus gas terminal. 

The scope of the project involves the design, procurement, fabrication, installation, 

commissioning and handover of: 

• 1 development well; 

• a 2 km 6” production pipeline from Bardolino to Howe; 

• a 2 km 3” gas-lift line from Bardolino to Howe; 

• a 2 km electro-hydraulic control and chemical umbilical from Bardolino to Howe; 

• a production tree and manifold at Bardolino; 

• a valve skid adjacent to the existing Howe manifold; and 

• modifications to the Nelson platform to provide capacity for the injection of H2S 

scavenger for treatment of Bardolino fluids. 

A graphical illustration of the proposed Bardolino Development is given as Figure 1.2. 

Figure 1.2: Proposed Bardolino Development 

Page 1-2 April 2008


1.3 PURPOSE OF THE ENVIRONMENTAL STATEMENT 

The EIA and ES have been carried out in accordance with the requirements of the Offshore 

Petroleum Production and Pipelines (Assessment of Environmental Effects) 

Regulations 1999 (s amended. The regulations implement, for offshore oil and gas activity, 

the requirements of EC Directive 85/337 on The Assessment of the Effects of Certain 

Public and Private Projects on the Environment. Under this, oil and gas projects fall under 

Annex 2 projects, for which an EIA is discretionary. 

Under the Offshore Petroleum Production and Pipelines (Assessment of Environmental 

Effects) Regulations 1999 as amended, there is a requirement to submit to the regulatory 

authority (Department of Business Environment and Regulatory Reform (BERR)) an ES for 

projects that are designed to produce 500 t (3,750 bbl) or more per day of oil or 500,000 cubic 

metres (17.5 million scf) or more of gas per day. As the Bardolino project is expected to 

exceed this threshold, the submission is a legal requirement. 

As required by both UK legislation and Shell Corporate Policy, the purpose of carrying out an 

EIA for the Bardolino Development is to ensure the integration of environmental 

considerations into project planning. Through an assessment of the proposals for the project, 

the EIA aims to identify whether there is any potential for environmental impact and, if there 

is, to propose mitigation techniques so that the project can be constructed, installed and 

operated without causing undue adverse environmental effect. The purpose of the ES is to 

report on the process of assessment and its results. 

Notwithstanding regulatory requirements, EIAs are routinely carried out by Shell for all 

offshore development activities as a matter of company policy. Shell has 13 Global 

Environmental Standards (GES) that must be considered by all operations. The EIA and ES, 

therefore, also serve to fulfil the requirements of Shell’s own Environmental Management 

System (EMS) and to ensure that all aspects of the development operations meet both 

regulatory and company standards of environmental performance. Both the EIA and ES were 

carried out and compiled in conjunction with an external third party. 

1.4 SCOPE OF THE ENVIRONMENTAL STATEMENT 

The assessment includes the effects, on all relevant components of the offshore environment, 

of planned activities associated with the proposed Bardolino Development. Project activities 

include: 

• Well Engineering Activities: The drilling, completion and well test of one 

development well at the Bardolino field. 

• Subsea Infrastructure Installation and Commissioning: (i) The installation and 

commissioning of a 2 km, 6" production pipeline and piggyback 3” gas lift line, and a 

separate electro-hydraulic and chemical control umbilical, between Bardolino and the 

Howe existing manifold. (ii) The installation and commissioning of a new manifold 

and tree at Bardolino, and a new valve skid at Howe. 

• Existing Facilities Modification and Commissioning: The installation and 

commissioning of new H2S scavenger facilities at the Nelson platform. 

• Production, Utility and Maintenance Operations: The operation of the Bardolino 

facilities and the effects of Bardolino processing on the Nelson platform. 

• Well Abandonment and Decommissioning: This will not be addressed in this ES – 

a separate environmental assessment will be undertaken at the appropriate time (see 

Section 3.8). 

April 2008 Page 1-3


1.5 LEGISLATION AND COMPLIANCE 

Shell is committed to compliance with legislative requirements. Project development and 

implementation is conducted within criteria set by legislation, and operations will be carried 

out in compliance with required permits and consents. A description of legislation relevant to 

the proposed Bardolino Development is provided in Appendix 1. 

Shell U.K. Limited (Shell) has a formal Corporate Management System (CMS) that is 

designed to facilitate the implementation of the Health, Safety and Environment (HSE) policy 

(Appendix 2) within all Shell business processes, asset groups and support services. The 

CMS describes how Shell manages environmental protection throughout its business. Shell 

UK’s Environmental Management System (EMS) is embedded in the CMS and the EMS is 

certified to the International Standards Organisation (ISO) Standard 14001 for Environmental 

Management Systems (EMS). 

1.6 CONSULTATION 

Consultation with stakeholders is an important part of the EIA process. A consultation 

exercise with government agencies, statutory nature conservation bodies and other 

environmental and community groups is being carried out during the planning phase of the 

proposed project. 

Before the ES was submitted for both public consultation and review by the Department for 

Business, Enterprise and Regulatory Reform (BERR), other potential stakeholders that may 

have an interest in the operations, namely local authorities, fisheries organisations and 

conservation groups, were identified and contacted (Table 1.1). Copies of the consultation 

letter and the responses received are provided in Appendix 3. The purpose of this initial 

informal consultation was to inform potential stakeholders about the proposed development 

and to invite them to participate in further dialogue. In addition, all regulatory stakeholders 

have been kept informed of the planned operations to ensure that any potential issues or 

concerns are raised and addressed appropriately. 

To date, meetings have been held with the Joint Nature Conservation Committee (JNCC) and 

BERR. The main issues raised to date from the consultation exercise, and how Shell is 

planning to address them, are summarised in Table 1.1. Where appropriate, the relevant 

section of the ES has been highlighted. 

Page 1-4 April 2008


Table 1.1: Summary of consultations undertaken 

Date Consultees Issues Discussed 

25 th Feb 2008 Meeting: JNCC & BERR JNCC indicated that survey data for the pipeline should 

ideally be presented within the ES. As the project 

involves only a 2 km long line, 1 km of which will be 

within the 500 m zones of Bardolino and Howe, JNCC 

suggested that if the data is not available the survey 

work that has/will be undertaken be described within 

the ES with further details, including results, provided in 

the subsequent PON 15s. 

13 th Mar 2008 Scottish Fisherman’s 

Federation (SFF) 

13 th Mar 2008 Fisheries Research 

Service (FRS) 

13 th Mar 2008 Marine Conservation 

Society 

13 th Mar 2008 Royal Society for the 

protection of Bird 

(RSPB) 

JNCC do not believe that modelling of drill cuttings 

would add to the ES application and would not expect 

this work to be undertaken. 

JNCC advised that within the ES, Shell should consider 

whether any of their activities are likely to cause 

'deliberate disturbances’ to a European Protected 

Species. Whilst Shell need to carry out the assessment, 

JNCC believe that the use of an MMO, daylight piling, 

and other measures, are likely to provide sufficient 

mitigation. 

Consultation letter sent to both JNCC and BERR on 13 th 

March 2008. 

Consultation letter sent. No response prior to 

submission of the ES. 

Consultation letter sent. Responded asking to be kept 

informed on the progress of the project. 





13 th Mar 2008 Defence Estates Consultation letter sent. Responded indicating an 

interest in an opportunity to discuss the development. 

13 th Mar 2008 Aberdeen Coastguard 

Offshore Oil & Gas 

Team 

13 th Mar 2008 Coastguard Agency 

MPCU 

13 th Mar 2008 Scottish Government 

Marine Directorate 

1.7 AREAS OF UNCERTAINTY 







Several aspects of the proposed development plan described in this ES are subject to a 

degree of uncertainty, as a result of the level of technical definition appropriate for the current 

stage of the project. These are discussed at appropriate points in the text of the ES, together 

with any significant implications with respect to environmental impact. The most important of 

these uncertainties are: 

� Unforeseen problems during drilling (such as geological obstruction or mechanical 

failure) may require the well to be side-tracked, or a spare well slot to be used. 

April 2008 Page 1-5


� It is possible that the predicted types and quantities of mud chemicals may change 

prior to drilling and this will be reflected in the PON 15B submission for a Permit to 

Operate under the Offshore Chemical Regulations 2002. 

� A stock of contingency chemicals will be kept on the drilling rig for use in the event 

that significant difficulties are encountered during drilling. It is not possible to predict 

whether these chemicals will be required, but they will be present in PON 15B 

submissions. 

� The exact method of filling the pipelines trenches has yet to be determined and will 

depend on a variety of geotechnical and safety considerations. The environmental 

implications for different options for stabilising the pipelines are assessed and 

compared in the ES. 

� The timing and sequence of work for the development may be adjusted as the 

operations proceed, as a result of planning improvements, weather conditions or 

other unforeseen circumstances. 

1.8 FORMAT OF THE STATEMENT 

The ES is laid out under the following sections: 

Non-Technical Summary 

Section 1 Introduction 

Section 2 Environmental Management 

Section 3 Project Description 

Section 4 Environment Description 

Section 5 Evaluation of Potential Environmental Impacts 

Section 6 Assessment of Potentially Significant Environmental Impacts 

Section 7 Conclusions 

Section 8 References 

Appendices 

Page 1-6 April 2008


2 ENVIRONMENTAL MANAGEMENT 

Shell U.K. Limited (Shell) has a formal Corporate Management System (CMS) that is 

designed to facilitate the implementation of the Health, Safety and Environment (HSE) policy 

(Appendix 2) within all Shell business processes, asset groups and support services. The 

CMS describes how Shell manages environmental protection throughout its business. Shell 

UK’s Environmental Management System (EMS) is embedded in the CMS and is 

independently verified to ISO 14001, which meets the requirements of OSPAR 

Recommendation 2003/5. A brief description of our EMS is given in section 3.1 of our 

previous public environmental statement, which can be accessed by the following link: 

• Shell Environmental Report 

The proposed development will fall within the scope of the EMS, and environmental protection 

is considered at all stages of the life cycle of Shell’s oil and gas facilities. This section 

provides a summary of all elements of the CMS and describes how these will be applied to 

the proposed Bardolino development. The specific environmental commitments made by 

Shell for the Bardolino development throughout the ES are summarised in Section 7, Table 

7.1. 

2.1 POLICY 

A copy of the Shell Policy on HSE is provided in Appendix 2. This Policy contains a 

commitment to protect the environment and states that we have a systematic approach to 

HSE management designed to ensure compliance with the law and to achieve continuous 

performance improvement. 

2.2 HSE PLAN 

A Bardolino Project HSE Plan has been developed for all phases of the development of the 

Project. This document sets out how health and environmental issues will be managed and 

how effective implementation of Shell’s Health, Safety and Environmental Policies and 

Corporate Management System (CMS) will be achieved. It applies to all work carried out on 

the project, whether it be carried out in Shell or contractors’ offices, construction sites, or 

vessels. 

This Project HSE Plan sets out: 

� How health, safety and environmental issues will be managed. 

� How effective implementation of Shell’s Health, Safety and Environmental Policies and 

Corporate Management System will be achieved. 

2.3 PLANNING 

All Bardolino Development activities will be managed in accordance with Shell’s CMS and 

supporting procedures. The potential environmental aspects of the activities (discussed in 

Sections 5 and 6) have been assessed by Shell, and appropriate controls are in place to 

ensure that these do not lead to adverse impacts on the environment. 

The Shell U.K. Limited Policy on HSE contains a commitment to comply with environmental 

legislation and other requirements. In addition to legal requirements, Shell also has a number 

of Shell Group requirements, which set targets and require reporting of performance for Shell 

Group companies. 

Shell promotes compliance and continuous improvement in performance by establishing 

appropriate environmental objectives and targets within an annual HSE Plan. The Bardolino 

April 2008 Page 2-1


Development would be designed to comply with Shell’s overall environmental objectives and 

targets. 

2.4 IMPLEMENTATION AND OPERATION 

The general responsibilities for health, safety and environmental protection are specified in 

Shell’s policy booklet (which is issued to all staff and contractors). Contractor companies 

undertake many activities, so the management of HSE protection by contractors is an 

important area for Shell. All contractors are required to fulfil defined standards in HSE 

management before they work with Shell, and their performance in this area is monitored and 

reviewed. Shell has an extensive assurance programme which includes a comprehensive 

programme of environmental audits. Shell also has HSE Interface Documents with 

contractors, and contractor audits are carried out. This ensures that the competence and 

standards of contractors are checked. Specific HSE responsibilities for the Bardolino 

Development would be set out in the Interface Document between Shell and the main 

contractors. 

Shell provides training to ensure that personnel are competent to carry out their activities, and 

where there are specific responsibilities for environmental protection specific training is 

provided. Contractor companies are expected to provide an equivalent level of training and 

this is checked at the tender stage of projects. Contractor competency, ensuring that the 

correct training and relevant qualifications have been achieved, is checked during the tender 

document assessment. 

Communication on environmental issues takes place primarily via line managers and 

supervisors. In addition, Shell has a comprehensive system of committees, meetings and 

publications that ensure the flow of information between all parts of the organisation. 

Environmental Specialists are available to provide advice to management on environmental 

matters. 

Communication with the authorities and interested parties is also an important part of Shell’s 

approach to environmental management. External consultations that have taken place during 

the environmental assessment stage of the project are described in Section 1.6. 

The main Shell environmental documents are sign-posted in the CMS and its supporting 

documents, including the E-Case documents which cover all assets and operations. Shell 

specifies certain operational controls that are to be implemented throughout the company. 

The main controls related to the proposed Bardolino Development are referenced at relevant 

points within the ES. 

A system of emergency preparedness and response is maintained by Shell to ensure that the 

correct action is taken in the event of an incident or accident that could affect the 

environment. The arrangements that would cover activities associated with the proposed 

Bardolino Development, and in particular the oil spill contingency planning arrangements, are 

described in the Section 6. 

2.5 CHECKING AND CORRECTIVE ACTION 

Commitment to continuous improvement in environmental performance underpins the Shell 

CMS. The Company monitors a range of environmental performance indicators and these 

are used to set improvement targets for important emissions and discharges that are 

considered to be significant. Proposed activities and operations are reviewed against these 

targets, enabling technical and operational controls to be identified and implemented. 

Emissions and discharges associated with the Bardolino Development would be monitored as 

part of Shell’s environmental measurement and monitoring programmes. Results would be 

used to review the environmental performance of the facilities and take appropriate corrective 

action. Performance reports would be provided to the authorities, via the Environmental 

Emissions Monitoring Scheme (EEMS), and to the Shell Group, as required. These 

requirements are identified in this ES. 

Page 2-2 April 2008


As a requirement of ISO 14001, environmental considerations are integrated into audit 

programmes that address all aspects of Shell’s business. Project reviews and installation 

audits and inspections conducted by Shell, and by the regulatory authorities and Verification 

Bodies, help to ensure that standards are being maintained and corrective action is taken 

where necessary. 

2.6 MANAGEMENT REVIEW 

The leadership teams throughout Shell carry out regular reviews of the CMS. The reviews 

take into account any relevant matters including the findings of audits, non-conformances and 

environmental performance. During the planning and operational phases of the proposed 

Bardolino Development, the Project Manager is responsible for ensuring that the CMS is 

applied to all activities. 

April 2008 Page 2-3



Page 2-4 April 2008


3 PROJECT DESCRIPTION 

3.1 INTRODUCTION 

This chapter summarises the development options that were considered for the Bardolino 

field and describes the option which has subsequently been selected. The main features of 

the selected option are described, focusing in particular upon aspects that are likely to have a 

potential impact on the environment. These include aspects that could lead to physical 

changes in the environment, as well as atmospheric emissions, aqueous discharges released 

offshore, or wastes returned to shore for treatment and disposal. Routine, emergency and 

accidental events are also considered. 

3.2 ALTERNATIVE CONCEPTS FOR FIELD DEVELOPMENT 

Two different infrastructure options were considered for the Bardolino Field Development. 

The options for recovering Bardolino’s reserves have been assessed to determine the most 

favourable option, taking into account the economic, technical, commercial, safety and 

environmental challenges of the project. 

It is a Shell requirement for any project that throughout the development of a project 

integrated decision-making is applied and an assessment of the project is carried out with 

respect to the seven Shell Group Sustainable Development (SD) principles. SD is about 

balancing and integrating the economic, social and environmental dimensions of the 

business. 

Various concepts were assessed using the Shell Exploration and Production Europe’s (Shell 

EPE) Sustainable Development Guidelines. The Bardolino project therefore addressed 

Shell’s sustainability principles of: 

� Respect and safeguard people 

� Protect the environment 

� Work with stakeholders 

� Manage resources 

� Generate robust profitability 

� Benefit communities 

� Deliver value to customers 

The different infrastructure options for Bardolino were assessed in terms of the three main 

project phases, namely; well engineering; installation and commissioning; and production 

operations. Each phase was assessed against the seven SD principles. The 

decommissioning activities will be addressed separately (Section 3.8). 

Within the SD assessments, specific focus was given to the safety element (“Respect and 

safeguard people”), which will be addressed by the completion of a separate comparative 

Hazard Identification assessment (HAZID), and to the environmental element (“Protect the 

environment”), which was addressed by the completion of a comparative Environmental 

Assessment. The main findings of the workshop assessments are discussed in the following 

sections. 

3.2.1 Selection of Development Concept 

The following two viable infrastructure options were assessed for the Bardolino development: 

1 Remote subsea development with 3.5 km tie-back to Howe Drill Centre. Since the 

initial development option study, the proposed well location was moved to a position 2 

km from the Howe PTS. This was to ensure that the field area did not extend into the 

adjacent Howe block and to avoid the need for a subsea pipeline crossing over the 

Langeled pipeline. 

April 2008 Page 3-1


2 Subsea development with deviated well drilled from Howe Drill Centre. 

A brief description of each of these options and summaries of the findings of the 

technical/economic evaluation and environmental evaluation are provided in Table 3.1. 

A number of the environmental aspects reviewed for each phase of the development were 

assessed as ‘neutral’ to concept selection, i.e. no significant differences could be identified 

between the two concept options. Whilst these are not included within Table 3.1 they are 

summarised as follows: 

• The issues and potential impacts associated with decommissioning were considered 

to be similar for both options. These included the land and sea contamination from 

structural residue following abandonment. 

• Hydrocarbon production and facilities integrity assurance were considered similar for 

both options. The ultimate production route would be from Howe through to Nelson, 

with no differences during routine operations. 

Page 3-2 April 2008


Table 3.1: Overview of the Bardolino Development concept selection 

Concept Concept Description Technical Evaluation Environmental Evaluation 

1. Remote subsea 

development with 3.5 km 

tie-back to Howe Drill 

Centre. 

Note -Since the initial 

development option 

study, the proposed well 

location was moved to a 

position 2 km from the 

Howe PTS. This was to 

ensure that the field are 

did not extend into the 

adjacent Howe block and 

to avoid the need for a 

subsea pipeline crossing 

over the Langeled 

pipeline. 

2. Subsea development 

with deviated well drilled 

from Howe Drill Centre. 

• Single well drilled from mobile drilling 

unit (92 days) 

• Production manifold and pipeline 

installation from Bardolino well to 

Howe 

• Production route through Howe to 

existing Nelson Platform 

• Modifications to Nelson 

• Single well drilled from mobile drilling 

unit (110 days), longer top hole 

section and more cuttings 

• No new pipeline installation, or 

production manifold installation 

• Production route through Howe to 

existing Nelson Platform 

• Modifications to Nelson 

• Tried and tested methodology 

• A combination of longer reach 

drilling with high temperature 

reservoir would give higher 

risks during the execution 

phase. The project risk would 

be less attractive to Shell with 

this concept. 

• Key Strengths: Shorter drilling time therefore lower 

emissions to air and sea. Shorter well bore therefore 

lower volumes of generated cuttings and chemical use 

and discharge. 

• Key weaknesses: Pipeline installation required with 

associated vessel use, increased seabed footprint and 

chemical use and discharge. 

• Key Strengths: No pipeline installation required, 

smaller amount of seabed disturbance. 

• Key Weaknesses: Longer drilling time, more emissions 

to air and sea. Longer top hole section generating 

greater volume of cuttings and requiring more use and 

discharge of chemicals. 

April 2008 Page 3-3


The concept selection assessment described above concluded that although the 

environmental effects of each option are similar, the drilling of a remote single well tied-back 

to the Howe Drill Centre is favoured in sustainable development terms. The comparative 

environmental assessment gave identical summary scores for both options although each 

option scored differently for the various phases of the development. 

The results of the SD assessment were integrated into the final Concept Selection Report for 

the project, which selected Option 1, a remote subsea development, as the proposed concept 

for the development of the Bardolino field. 

3.3 OVERVIEW OF PROPOSED PROJECT AND SCHEDULE 

This section describes the main features of the selected development option. This includes 

any aspects of the project that could lead to physical changes in the environment, incremental 

use of resources by existing facilities within the area, and any additional discharges, 

emissions and wastes released offshore or returned to shore for disposal. 

Following a brief overview of the project and the anticipated schedule, the following project 

phases are described: 

• Well engineering (Section 3.4) 

• Subsea infrastructure installation and commissioning (Section 3.5) 

• Existing facilities modification and commissioning (Section 3.6) 

• Production, Utility and Maintenance Operations (Section 3.7) 

• Well Abandonment and Decommissioning (Section 3.8) 

3.3.1 Project Overview 

The Bardolino field is located in Block 22/13 in the central North Sea (Latitude 57° 38’ 00.9”N, 

Longitude 01° 24’ 07.3”E) in a water depth of approximately 91 m (Figure 3.1). 

Page 3-4 April 2008


Figure 3.1: Location of the Bardolino development 

Bardolino is jointly owned by Shell (62%) and OMV (38%) and will be operated by Shell. The 

Bardolino well will target production from the Fulmar and Hugin sands of the reservoir and is 

expected to produce at a gas oil ratio (GOR) of approximately 870 scf/bbl. Ultimate maximum 

recovery (high case) from Bardolino is estimated to be in the region of 13.2 million barrels of 

oil and 11.96 billion scf of gas. 

The proposed Bardolino development will comprise a single well, production tree and 

manifold, tied back to the existing Howe production manifold via a 2 km 6” production pipeline 

with piggyback 3” gas lift line, and a separate electro-hydraulic control and chemical umbilical. 

The pipelines and umbilical will be installed in 2 separate trenches between the new 

Bardolino manifold and existing Howe manifold (Figure 3.2). 

Produced fluids from Bardolino will be transported via the existing infrastructure at Howe to 

the Nelson platform for processing and export to shore. Oil is exported from Nelson by 

pipeline to the nearby BP Unity platform and then by the Forties pipeline to the landfall at 

Cruden Bay. Gas is exported via the Fulmar gas pipeline to the St. Fergus gas terminal. 

April 2008 Page 3-5


Figure 3.2: Schematic of the proposed Bardolino development 

The Howe field is located entirely in Block 22/12a (Latitude 57° 38’ 27.745’’ N, Longitude 01° 

22’ 19.776’’ E), 14 km east south east of the Nelson platform, in a water depth of 85 m. The 

Howe subsea satellite development comprises a single production well directly tied back to 

the Nelson platform via an 8” flowline and 3” gas lift flowline. An umbilical connects the Howe 

Subsea Control Module to the Nelson Installation. The pipelines and umbilical are tied to 

Nelson via a spare 6” production riser, spare 3” gas lift riser and J-tube. 

The Nelson field is located in U.K. Licence Blocks 22/6a, 22/11, 22/1 2a and 22/7 in the 

central North Sea. The Nelson installation comprises a single, manned drilling and production 

platform and a subsea satellite development tied back to the platform. The platform stands in 

84 m of water, and is approximately 204 km east of Aberdeen (Latitude 57° 39' 46.353" N, 

Longitude 01° 08’44.029" E) in Licence Block 22/11. The Nelson subsea satellite is located 

5.8 km to the south of the platform, (Latitude 57° 37' 00" N, Longitude 01° 11' 30" E) in 

Licence Block 22/11. The nearest platform is BP’s Forties E platform, approximately 8 km to 

the northwest. 

The proposed well location has been selected to ensure that the field area does not extend 

into the adjacent Howe block. The well will be 139 m from the Langeled pipeline, and its 

location has been chosen to avoid the need for a subsea pipeline crossing. 

In summary, the scope of the project involves the design, procurement, fabrication, drilling, 

installation, commissioning and handover of: 

• 1 development well; 

• a 2 km 6” production pipeline from Bardolino to Howe; 

• a 2 km 3” gas-lift line from Bardolino to Howe, piggybacked to the 6” production 

pipeline; 

• a 2 km electro-hydraulic control and chemical umbilical from Bardolino to Howe; 

• a production tree and manifold at Bardolino; 

• a valve skid adjacent to the existing Howe manifold; and 

• modifications to the Nelson platform to provide capacity for the injection of H2S 

scavenger for treatment of Bardolino fluids. 

Page 3-6 April 2008


3.3.2 Project Schedule 

Current planning is for first oil from the Bardolino development in August 2009. The 

approximate timings of key phases of the project, based on current planning, are given in 

Table 3.2. 

Table 3.2: Project schedule for the Bardolino Development 

Activity Proposed Start Likely Duration 

Drilling development well March 2009 3 months 

Pipeline installation June 2009 6 weeks 

Hook-up and commissioning July 2009 2 weeks 

Nelson Topsides modifications February 2009 4 months 

First oil date August 2009 Ongoing 

3.4 WELL ENGINEERING 

3.4.1 Drilling Programme 

The development plan for Bardolino involves the drilling of one production well. The drilling 

phase is expected to commence in March 2009 and is anticipated to continue for three 

months. The activities and potential impacts of the drilling operation are discussed in more 

detail in the following sections. 

3.4.2 Drilling Rig 

At the time of preparation of this document the planned drilling rig to be used for the Bardolino 

development is Transocean’s semi-submersible drilling rig Arctic IV. The Transocean Arctic 

IV rig is accredited for use in the UKCS and will be subject to Shell’s contractual conditions. 

3.4.3 Positioning and Anchoring the Rig 

The Arctic IV semi-submersible drilling rig will be towed out to the drilling location by two or 

more tugs. The tow route will be selected in consultation with other users of the sea to 

minimise interference with other vessels. As required by the Health & Safety Executive 

(HSE) Operations Notice 6, a rig warning communication will be issued at least 48 hours 

prior to any rig move. The routes will be selected in consultation with other users of the sea 

to minimise interference and risk of collision with other vessels. 

Once the rig arrives at the field, it will be positioned over the drilling location with the 

assistance of three Anchor Handling Tug Vessels (AHTVs) and maintained on station by eight 

or more anchors. This will be undertaken in accordance with Shell procedures. 

In accordance with safety legislation a statutory 500 m safety zone will be established around 

the drilling rig once it is on location. Unauthorised vessels, including fishing vessels and 

commercial shipping, are not permitted access to this area. A standby vessel will be on 

station throughout the drilling operations in case of any emergency necessitating evacuation, 

or a man-overboard situation, and to warn any unauthorised vessels approaching the safety 

zone. 

Supply vessels will transport drilling equipment, supplies, water, fuel and food to the rig and 

return wastes and surplus equipment to shore. Helicopters will be used to effect personnel 

transfers to and from the drilling unit. 

3.4.4 Overboard Discharges from Rig 

The Arctic IV drilling rig will have appropriate drainage, sewage and waste disposal systems 

that meet the requirements of all applicable legislation. Any drainage water from areas that 

may be contaminated with traces of oil (e.g. bilge and machinery space drainage, drilling area 

drainage) will be treated in an oil/water separator to remove free oil. Oil recovered from the 

separator system will be returned to shore for disposal with other wastes. These oil transfers 

will be recorded in the Oil Record Book for the rig as required by the Merchant Shipping 

(Prevention of Oil Pollution) Regulations 1996 (as amended), which along with associated 

April 2008 Page 3-7


Regulations, enacts the MARPOL convention. The water will be cleaned to a standard of at 

least 15 parts per million (ppm) of oil in water before being discharged overboard. The 

volumes of water discharged from this source will be small and are not considered to be of 

environmental concern. 

Where appropriate, discharges containing chemicals will be subject to a Chemical Risk 

Assessment and will require a permit under the Offshore Chemical Regulations 2002. 

Sewage and other wastewater from crew accommodation will be discharged into the sea from 

the rig via the sewage treatment plant. The quantities of treated sewage will be small in 

comparison to the dilution available and they are therefore considered to be of no 

environmental concern. 

All domestic wastes and general rubbish generated during drilling operations will be 

segregated and bagged, or stored in skips on board the drilling unit in accordance with the rig 

Waste Management Plan, which is required under the Merchant Shipping (Prevention of 

Pollution by Garbage) Regulations 1998. The only exception to this is food waste, which 

may be discharged to sea provided maceration processes are used to ensure it is capable of 

passing through a 25 mm mesh screen. All other solid wastes will be returned to shore for 

disposal as controlled and special waste at licensed waste disposal sites, or for approved 

recycling in compliance with company policy and with the requirements of the Environmental 

Protection Act 1990 and associated Regulations. Shell procedures document the 

segregation and reduction of waste through liaison with suppliers, re-use of packaging and 

minimisation of hazardous waste. 

3.4.5 Well Design 

The well design is currently at a preliminary stage; the data provided is the current base plan 

and may be subject to change. Any changes are unlikely to significantly alter the overall 

environmental impact since the base case is firm and the timing represents the anticipated 

drilling time. The detailed well design will be provided in a PON 15B permit application 

submitted to BERR at least 28 days prior to drilling activities. 

The Bardolino development well (22/13a – P1) will be drilled as a deviated well. The well 

design consists of a 36” top hole section with a 30” conductor. The remaining sections will 

require a 20”, 13 5/8“ and 10 3/4” full casing string and 7 5/8” production liner, requiring 26”, 

17 ½”, 12 ¼” and 8 ½“ hole sizes to be drilled with a 6 1/8” hole section drilled through the 

reservoir (Figure 3.3). 

Page 3-8 April 2008


Figure 3.3: Bardolino well design schematic 

sea bed @ 422 ft 

Nordaland / 30" shoe @ 

Undifferentiated 650 ft 

Lark 

Horda 

Balder 

Sele 

Forties 

Maureen 

Ekofisk 

Tor 

Hod 

Kimmeridge 

20" shoe @ 

3000 ft 

13 5/8" shoe @ 

6500 ft TBC 

9 7/8" shoe @ 

12326 ft 

7-5/8" Shoe @ 

Fulmar 12969 ft 

Hugin 4-1/2" Shoe @ 

Pentland 13554 ft 

The Bardolino development well will be drilled using conventional drilling techniques and it is 

estimated that a total of approximately 863 t of water-based mud (WBM) cuttings and 830 t of 

low-toxicity based mud (LTOBM) cuttings will be produced during drilling (Table 3.3). 

April 2008 Page 3-9


Table 3.3: Proposed well design and estimated cuttings for the Bardolino development 

well 

Hole Diameter (inches) Mud type Section Length (m) 

Estimated Mass of 

Cuttings (tonnes)* 

36 WBM 198 299 

26 WBM 716 564 

17 1/2 LTOBM 1,677 598 

12 1/4 LTOBM 1,166 204 

8 1/2 LTOBM 234 20 

6 1/8 LTOBM 178 8 

Total Mass of Cuttings (t) 1,693 

*Quantities based on an average rock density of 2300 kg/m 3 

The mass of cuttings quoted is a worst-case estimate for the well, but does not include any 

cuttings arising from unplanned sidetracks. Should a sidetrack be necessary, this would 

increase mud and chemical use and discharges by approximately 50% per well. Any 

changes will be reflected in Shell’s PON 15B submission and associated variations to BERR. 

3.4.6 Drilling Fluids and Chemicals 

The function of the drilling mud is primarily to cool and lubricate the drill bit, prevent well kick, 

transport the cuttings to surface and prevent the bore hole from caving in behind the bit. 

Drilling mud provides the hydrostatic pressure necessary to prevent fluids from entering the 

well bore and is the primary method of well control. Drilling fluid is continuously pumped 

down the drill string to the drill bit and returns to the surface through the annular space 

between the drill string and the sides of the well. 

Drilling mud comprises a base fluid, weighting agents and chemicals that are used to give the 

mud the exact properties it needs to make it as easy and safe as possible to drill the hole. A 

mud programme is developed for each well. Each wellbore section will require a mud 

programme with primary and contingency chemicals applied to maintain the range of physical 

and chemical properties, enabling it to perform all of its functions adequately. Table 3.3 

summarises the proposed mud types and system for the Bardolino development well. It is 

planned to drill the 36” and 26” sections of the well with WBM; all other sections will be drilled 

using low toxicity oil based mud (LTOBM). 

The 36” and 26” hole sections will be drilled riserless using seawater and Bentonite clay 

additives / sweeps, with all WBM mud and cuttings discharged directly to the seabed during 

drilling. The impact of the discharge of WBM cuttings directly to the seabed is assessed in 

Section 6.3. Following the drilling of these hole sections and installation of the 30” conductor, 

26” casing and blow-out prevent stack (BOP), a riser will be installed between the well and 

the drilling rig. This will enable all LTOBM mud and cuttings to be returned to the rig for 

containment. 

The LTOBM mud and cuttings will leave the drill hole through the mud return line and fall over 

a series of vibrating, screen-like devices, known as shale shakers. The shakers will screen 

out the cuttings, which will be contained in skips on the drilling rig to be subsequently shipped 

to shore for disposal. The recovered mud will drain back into the mud pits and will be 

recycled back down the hole by the mud pump. The circulating system is essentially a closed 

system; the mud will be recycled throughout the drilling of the well. Constituents will be 

added to make up for losses, adjust the mud’s properties, or overcome difficult conditions 

(e.g. a stuck drill pipe or loss of well pressure or fluid). 

The exact chemical constituents required to formulate the drilling muds and chemicals are yet 

to be confirmed. These will be included in the detailed risk assessment for drilling fluids and 

chemicals which will be submitted to BERR in the form of a PON 15B at least 28 days prior to 

the commencement of the drilling activities as required by the Offshore Chemical 

Regulations 2002. 

Page 3-10 April 2008


3.4.7 Cementing Chemicals 

Cement is used to secure the steel casing in the well bore, and the cementing chemicals are 

used to modify the technical properties of the cement slurry. During cementing operations, 

the majority of these chemicals are left downhole but a small quantity of cement may be 

discharged onto the seabed around the top of the casing. However, the chemicals used will 

be contained within inert cement and will therefore not pose a threat to the marine 

environment. Careful estimates of the final volume of the hole will be made during drilling, 

and the volume of cement used will be adjusted accordingly to minimise the risk of excess 

cement being squeezed out of the hole onto the seabed. 

A number of chemicals will need to be added to the cement. The exact chemical constituents 

required to formulate the cement will be confirmed during the final stages of well design. 

They will be included in the detailed chemical risk assessment of the PON 15B which will be 

submitted to BERR at least 28 days prior to commencement of drilling activities as required 

by the Offshore Chemical Regulations 2002. 

3.4.8 Contingency Chemicals 

Contingency chemicals will be held on the rig for use in unplanned events. Potential 

applications would be to free a stuck drill string, or seal highly porous or fractured zones to 

prevent the uncontrolled loss of drilling fluid. A detailed risk assessment for contingency 

chemical use will be submitted to BERR as required by the Offshore Chemical Regulations 

2002. 

3.4.9 Handling Mud and Cuttings 

Once on board the rig, drill cuttings are removed from the drilling mud by solids control 

equipment. Where LTOBM is used the mud and cuttings will be treated by the solids control 

equipment before being intercepted by a collection device. The cuttings will be transferred 

from the solids control equipment and then either dried and collected in skips ready for 

transfer to a supply vessel, or slurrified and pumped directly to the bulk tanks of a supply 

vessel for transport to shore. Once onshore the cuttings are processed until they have very 

low oil content and then disposed of. The base oil residue recovered during this process is 

returned to the mud company. 

Shell’s “Ship to Shore Cuttings Disposal Guidelines” will be followed during the planned 

LTOBM phase. In the event of unexpected hole conditions (e.g. faster than expected 

penetration rates), equipment breakdown or failure, or operational and logistics downtime due 

to adverse weather conditions, contingency arrangements will be in place to permit storage of 

cuttings on board the rig until normal operations are resumed. If necessary, unless personnel 

safety or installation integrity is threatened, drilling will cease in preference to the discharge of 

LTOBM-coated cuttings to sea. However, in the event of a major safety incident where no 

compromise on safety risks to personnel or asset can be made, the contingency will exist to 

divert limited quantities of cuttings overboard. 

3.4.10 Well Clean-up and Testing Operations 

Once drilling has been completed, the Bardolino well will be circulated clean prior to 

completion, and then tested. The exact chemicals required for these processes will be 

included in the chemical risk assessment of the PON 15B as required by the Offshore 

Chemical Regulations 2002. Hydrocarbons produced during the well flow clean-up and 

testing will be flared. 

The aim of well clean-up is to remove detritus from the well prior to running the completion. It 

also removes solids that could impair both mechanical operations in the well bore and 

reservoir performance once the well has been perforated. 

The potential emissions from well clean-up and testing of the development well have been 

calculated based on a total testing and clean-up period of 48 hours with a maximum of 15,000 

bbls of oil, with an expected GOR of 870 scf/bbl ( 

Table 3.4). This represents a worst case for emissions. There is no intention to perform an 

extended well test, and it is likely that the quantity of oil flared during well clean-up and testing 

April 2008 Page 3-11


operations will be less than approximately 8,000 bbls. The impact of emissions from the 

proposed well clean-up and testing is assessed in Section 6.3. 

Table 3.4: Summary of emissions (in tonnes) from flaring of gas and oil during well 

clean-up and testing for the Bardolino Development well 

Emissions CO2 CO NOx N20 SO2 CH4 VOC 

Oil (tonnes) 6,413.50 36.08 7.42 0.16 0.03 50.11 50.11 

Gas (tonnes) 941.06 2.25 0.40 0.03 0.004 15.12 1.68 

Total 7,354.57 38.33 7.82 0.19 0.03 65.23 51.79 

Note: Conversion factors based on UKOOA well testing emission factors, assuming 95% flare efficiency: 

Oil 3.2 0.018 0.0037 0.000081 0.0000128 0.025 0.025 

Gas 2.8 0.0067 0.0012 0.000081 0.0000127 0.045 0.005 

Source: 2002 EEMS Guidelines for the Compilation of an Atmospheric Emissions Inventory Revision 4 

3.4.11 Drilling Rig Utilities 

The utility operations of drilling vessels include such activities as facility maintenance, 

management of drainage, accommodation services and deck operations. 

3.4.12 Noise Emissions Resulting from Proposed Operations 

In general terms, sound can be characterised with reference to two features, the frequency at 

which it is emitted (measured in hertz (Hz)) and its strength or intensity. Noise from various 

sources may combine or cancel to produce a pattern of noise in the marine environment that 

is characterised by variations in frequency and noise level. Noise levels in the marine 

environment are attenuated by distance (dispersion in 3 dimensions), and by absorption by 

the water. The degree of absorption is roughly in proportion to the square of the frequency 

(Richardson et al., 1995). 

The dominant sound sources from the project result from: 

• a semi-submersible drilling rig; 

• a standby vessel; 

• 3 anchor handling tug vessels (AHTVs) 

• a guard vessel 

• a DP pipelay vessel (which utilises thrusters to maintain its position); 

• a trenching vessel 

• a survey / umbilical vessel; 

• a dive support vessel (DSV) to tie-in and commission pipeline; 

• a rock dump vessel; and, 

• piling the subsea structures (Section 3.6.2). 

Approximate noise levels can be calculated at given distances using formulae presented in 

Richardson et al. (1995), and a formula for absorption given by Erbe and Farmer (2000). 

Since the water depth in the development area is approximately 90 m, a model of cylindrical 

spreading has been used rather than spherical spreading. In relatively shallow water, 

cylindrical spreading results in a larger zone of influence than for spherical spreading in deep 

water. The formula used is: 

Lr = Ls – 15 log H – 5 log R – 60 (dB) 

Received Level (Lr) = Source Level (Ls) – correction for depth (H, km) – distance (R, km) 

attenuation – Correction between m and km 



The characteristics of the noises produced by different types of drilling platforms and vessels 

are shown in Table 3.5. Richardson et al. (1995) state that there are few published data on 

underwater noise levels near drilling platforms and on the responses of marine mammals 

near those facilities, but underwater noise levels may often be low, steady and not very 

disturbing. 

Table 3.5: Examples of underwater noise levels produced by different types of vessel 

or different types of activity 

Source Source levels of underwater noise 

(dB re 1µPa at 1m)* (predominant frequency if 

known) 

Median Ambient Level 80 to 100 

Drilling from semi-submersible 154 (100 to 500Hz) 

Tug / Barge 140 to 170 

Trenching 159 to 174 (500 Hz) 

Supply / Support Vessel 170 to 180 (500Hz) 

DP pipe laying vessel 177 (500-1,000Hz) 

Pile driver 206 

Helicopters (various) & at various 

altitudes 

101 to 109** 

Key: dB re1µPa at 1m – unit of Sound Pressure Levels measured at a 1m range from source 

* Most data taken from 1/3-octave band centre frequencies (50-2000Hz) 

** Measured at the water surface 

Source: Richardson et al. (1995); Evans and Nice (1996). 

Helicopters will make routine visits to the drilling rig, and the duration of audibility is variable. 

Richardson et al. (1995), quote an approaching noisy model of helicopter, the Bell 214ST, as 

being detectable underwater for only 38 s at 3 m depth and 11 s at 18 m. Underwater noise 

from a passing aircraft is generally brief in duration, especially when compared with the 

duration of audibility in the air. 

The impact noise emissions as a result of the proposed operations is assessed in Section 

6.7. 

3.4.13 Power Generation and Atmospheric Emissions 

Power on board the drilling rig and vessels will be provided by diesel-driven generators, and 

their use will result in the release of exhaust gases to the atmosphere. Anticipated fuel use 

for the Bardolino development (including drilling operations, pipe-laying and subsea 

infrastructure installation) is given in Table 3.6, and is based on typical average fuel 

consumption for a semi-submersible drilling rig and other relevant vessels. 



Table 3.6: Estimated atmospheric emissions from diesel fuel consumption for the 

Bardolino Development operations 

Operation/Activity Days 

Fuel 

cons 

Fuel 

cons Emissions per tonne 

t/day tonnes CO2 NOx SO2 

Factor marine diesel (UKOOA, 2002) 3.2 0.059 0.004 

Drilling rig 

mob/demob 4 25 100 320.00 5.90 0.40 

drilling 110 30 3300 10,560.00 194.70 13.20 

Standby vessel 

mob/demob 4 0.8 3.2 10.24 0.19 0.01 

drilling 14 0.7 9.8 31.36 0.58 0.04 

Anchor handling tug 

mob/demob 4 50 200 640.00 11.80 0.80 

drilling 4 5 20 64.00 1.18 0.08 


mob/demob 4 50 200 640.00 11.80 0.80 

drilling 4 5 20 64.00 1.18 0.08 


mob/demob 4 50 200 640.00 11.80 0.80 

drilling 4 5 20 64.00 1.18 0.08 

Guard vessel 

mob/demob 4 8 32 102.40 1.89 0.13 

drilling 160 4 640 2,048.00 37.76 2.56 

Pipelay vessel 

transit 4 8 32 102.40 1.89 0.13 

working 10 15 150 480.00 8.85 0.60 

Trenching vessel 

transit 4 50 200 640.00 11.80 0.80 

working 10 5 50 160.00 2.95 0.20 

Survey Vessel 

transit 4 22 88 281.60 5.19 0.35 

working 20 18 360 1,152.00 21.24 1.44 

DSV 

transit 4 22 88 281.60 5.19 0.35 

working 30 18 540 1,728.00 31.86 2.16 

Rock dump 

transit 4 10 40 128.00 2.36 0.16 

working 14 5 70 224.00 4.13 0.28 

Estimated total air emissions during drilling and 

installation 20,361.60 375.42 25.45 

Total 2005 emissions to air from UKCS offshore 

oil & gas installations 18,333,624.04 59,778.51 2,936.63 

% of total 2005 emissions to air from UKCS 

offshore oil & gas installations 0.11 0.63 0.87 

Source: Cordah (1999), UKOOA (2002) and learnIT (2006) 

The drilling rig will be on site throughout the well programme. Dedicated support and standby 

vessels will be on location for the duration of the operations. For the pipe-lay and umbilical 

installation operations, a DP lay barge, a DSV, a trenching vessel and a survey vessel will 

also be required to lay, tie-in and commission the pipeline. 



The consumption of diesel fuel during operations associated with drilling, trenching , pipelaying 

and piling operations will lead to the generation of carbon dioxide (CO2) and other 

exhaust gases. The proposed operations will result in the release of approximately 20,361 t 

of CO2, 375 t of nitrogen oxides (NOx) and 25 t of sulphur dioxide (SO2). 

3.5 INSTALLATION AND COMMISSIONING OF SUBSEA INFRASTRUCTURE 

3.5.1 Pipeline and Umbilical Routing 

The 6” production pipeline and piggybacked 3” gas lift pipeline will be laid in one trench, and 

the umbilical will be laid in a second trench located approximately 30 m away. The proposed 

route corridors for these pipelines between the Bardolino development well and Howe 

manifold are shown in Figure 3.5. Neither of the proposed routes will cross any other existing 

sub sea infrastructure. 

3.5.2 Pipeline System Design 

The proposed production pipeline is a 2 km, 6" diameter pipeline from the Bardolino manifold 

to the Howe manifold. The pipeline will be constructed from continuous welded corrosion 

resistant alloy (CRA), sufficient to cover the full closed in tubing head pressure (CITHP) of 

345 bar. The pipeline will be coated with polyethylene/ polypropylene to prevent external 

corrosion, supplemented by a sacrificial anode system. A 3" gas lift line will be piggy-backed 

to the production line; it will be made from the same materials and rated to the same design 

pressure of 345 bar (Figure 3.4). 

Figure 3.4: 3” and 6” pipelines in piggyback assembly 

The design and flow-rates of the pipelines are shown in 

Table 3.7. 



Table 3.7: Bardolino pipelines design 

Line Routing Size 

6" 

Production 

3" 

Gas lift 

Bardolino 

to Howe 

Bardolino 

to Howe 

6" diameter x 2 

km 

(28 m 3 volume) 

3" diameter x 2 

km 

(9 m 3 volume) 

Materials/ 

Rating 

Corrosionresistant 

alloy at 

345 bar 

Carbon steel at 

324 bar 

Installation 

method 

Trenched and 

potentially backfilled 

with rock dump 

along length of line 

Design 

Flow-Rate 

10,000 bbl/day 

Piggy-backed on 6" 

production line 6 MMscf/day 



Figure 3.5: Bardolino pipeline and umbilical routes corridor 



3.5.3 Pipeline Installation 

The pipe lay operations will be conducted by a DP vessel. The use of a DP vessel will avoid 

the use of anchors and so prevent localised disruption to the seabed caused by the repeated 

placement and retrieval of anchors. The DP vessel will generate more emissions to 

atmosphere from power generation than an anchored vessel, but no anchor handling vessels 

will be required, thereby reducing total emissions. The DP system may also create increased 

underwater noise through the use of thrusters. The overall activity is planned to last only 30 

days, however, and emissions and discharges during this time will be equivalent to those from 

normal shipping activities. 

Bridging documents between Shell and the installation contractors operating the pipeline 

installation vessels will describe the management structure and division of responsibilities that 

will prevail during the operations, the methodology for executing the work programme, and 

the emergency response procedures. 

At this stage it is planned that the piggyback pipelines will be laid in a single trench (with the 

umbilical laid in a separate, parallel trench) constructed by a towed pipeline plough. The 

trench is expected to be 1.8 m deep and 6.2 m wide at the top, with a 30 degree side slope 

(Figure 3.6), so the area of seabed disturbance for this pipeline’s trench would be 

approximately 12,400 m 2 . 

Figure 3.6: Trench and burial of the 6” and 3” piggyback pipelines 

Following ploughing, the pipelines will either be: 

1. Covered using a backfill plough to recover the excavated material back into the 

trench; or 

2. Blanket rock dumped along the 2 km length of the pipeline route from Bardolino to 

Howe, to cover the pipelines in the trench; or 

3. Covered using a backfill plough to recover the excavated material back into the 

trench, with some spot rock dumping limited to specific points where a risk of 

upheaval buckling is identified. 

The final selection of the installation method will be driven by both technical and economic 

considerations. If blanket cover were to be used, the total quantity of rock required would be 

approximately 20,000 t deposited from a DP vessel. The total area of seabed which would be 

covered by this rock dump would be approximately 6.2 m x 2 km (12,400 m 2 ) for the trench 

containing the piggyback pipelines. If a backfill plough is mobilised to cover the pipelines 

using the excavated material, and rock is used only for spot dumping of sections where the 



backfill is not sufficient to prevent upheaval buckling, the quantity of rock required should be 

less than 10,000 t (Figure 3.7). 

Figure 3.7: Open trench and rock dump of the 6” and 3” piggyback pipelines 

The operations will be monitored by a post-lay inspection using a Remotely Operated Vehicle 

(ROV). The subsequent status of the line, including any free spans, will be monitored in 

accordance with the Shell inspection and maintenance plans. 

3.5.4 Manifold, production tree and valve skid installation 

A new production manifold will be installed close to the Bardolino tree (Figure 3.8) by a single 

lift from a DP vessel. The manifold will be approximately 91 t and approximately 9 m x 6 m x 

4 m in dimension. The manifold will be fabricated within a piled, slab-sided protection 

structure, designed to withstand fishing interaction loads in addition to environmental and 

dropped object loads. The manifold protection structure will be secured to the seabed using 4 

hammer-driven piles, one at each corner of the structure. The piles will be 610 mm outside 

diameter and approximately 20 m long. 

A new Vetco standard frame production tree at the Bardolino well will be installed following 

the completion of drilling. The tree will be encased in a “cocoon” type protective structure 

which is designed to be ‘fishing friendly’ (i.e. if a fishing vessel is arrested the gear can be 

retrieved without snagging the tree equipment, thus avoiding damage to the gear or the 

seabed asset), and will be constructed from CRA (Figure 3.9). 



Figure 3.8: Example of manifold to be installed at Bardolino 

Figure 3.9: Illustration of a production tree fitted with a cocoon protective structure 

Cocoon production tree 

Production tree 

Seabed 



A valve skid will also be installed alongside the existing Howe manifold, with dimensions 4 m 

x 5.5 m x 3.5 m. The valve skid protection structure will also be secured to the seabed using 

piles, of smaller diameter and length than those required for the manifold structure. 

The total area of seabed which will be covered by the tree, manifold and valve skid will be 

approximately 56 m 2 . 

The tree, manifold and valve skid will be connected to the installed pipelines using flexible 

jumpers and spool pieces. Concrete mattresses will be used to protect these items of subsea 

infrastructure. The mattresses planned for use are likely to be standard density concrete of 

dimensions 6 m x 3 m x 1.5 m, with mattresses 6 x 3 x 0.3 m in dimension in areas of high 

risk to dropped objects. It is anticipated that 60 mattresses will be required at the Bardolino 

location to protect the manifold structure and tree, and 70 mattresses will be required at the 

Howe location. The total area of seabed that would be covered by the mattresses would be 

approximately 0.0023 km 2 . 

3.5.5 Pre-commissioning and testing the pipelines, manifold, valve skid and tree 

At this stage the full extent of the subsea pre-commissioning and commissioning is not fully 

defined. A worst-case estimate has therefore been made of the planned chemical use and 

discharge during pre-commissioning and commissioning activities for the 6” production 

pipeline, 3” gas lift line and umbilical. Efforts will be made to ensure that chemical use and 

discharge is minimised as far as possible through the detailed design stage of the project. 

In summary, pre-commissioning of the pipelines will be undertaken in three main phases: 

• pipeline flooding/ cleaning / gauging (i.e. monitoring pipe wall thickness); 

• pipeline system hydro-testing; and 

• de-watering in preparation for commissioning. 

When installed, the pipelines will contain atmospheric air. Immediately after installation, the 

6” production pipeline will be flooded with water to ensure stability on the seabed for 

trenching. The production pipeline may also be gauged during this operation to verify that 

there are no dents or buckles that could impair the integrity of the pipeline. The 3” gas lift 

pipeline will be subjected to a high velocity flush to ensure stability on the seabed for 

trenching and also verify that there are no dents or buckles that could impair the integrity of 

the pipeline. 

The water used for flooding, flushing and (optional) gauging of the pipelines will be filtered 

and dosed with the chemicals required to maintain the integrity of the pipelines during 

subsequent pre-commissioning and commissioning activities. These chemicals may include 

corrosion inhibitor, biocide and oxygen scavenger. Some treated water will be discharged to 

the environment during the flooding, flushing and (optional) gauging operation. The water will 

be seawater for the gas lift pipeline and potable water for the production pipeline. 

Following post-trench gauging, both pipelines will be subjected to a hydrostatic strength test 

to 1.5 times the design pressure for a period of 24 hours. The water used for the strength 

testing will be filtered and dosed with chemicals to maintain the integrity of the pipelines 

during subsequent pre-commissioning and commissioning activities. These chemicals may 

include corrosion inhibitor, biocide, oxygen scavenger and fluorescent dye. Some treated 

water will be discharged to the environment during strength testing activities. The water used 

for strength testing will be seawater for the gas lift pipeline and potable water for the 

production pipeline. 

On completion of the hydrostatic strength testing, the ends of the production pipeline would 

be filled with a water-based gel sealer gel to minimise seawater ingress during tie-in. A slug 

of gel would be injected into one end of the pipeline and then a slug of gel of half this volume 

would be injected into the opposite end. Some treated potable water will be discharged to the 

environment during the injection of the first slug and some gel will be discharged to the 

environment during injection of the second slug. 

The manifolds and tie-in spools to connect the manifolds, wells and pipelines will then be 

installed. All spools, and all manifold production and gas lift pipe work, will be pre-flooded 

with a glycol-based gel onshore prior to offshore shipment, deployment and installation. This 



will minimise the risk of seawater contact with the production pipeline during subsequent precommissioning 

activities, assist with the dewatering and conditioning effectiveness for both 

pipeline systems, and minimise the risk of hydrate formation during start-up. In addition, dye 

sticks will be installed at each tie-in flange location to assist with leak detection during 

subsequent pre-commissioning activities. 

The pipelines will then be tied-in to the existing subsea Howe manifold and the new Bardolino 

manifold, and the Bardolino manifold will also be tied-in to the subsea wellhead. After 

completion of tie-ins the completed pipeline systems will be subjected to a hydrostatic leak 

test at 1.1 times their design pressure to verify the integrity of the tie-in connections. The 

water used for the strength testing and leak testing will be filtered and dosed with chemicals 

to maintain the integrity of the pipelines during subsequent pre-commissioning and 

commissioning activities. These chemicals may include corrosion inhibitor, biocide, oxygen 

scavenger and fluorescent dye. Some treated water will be discharged to the environment 

during strength testing and leak testing activities. The water used for strength testing and 

leak testing will be seawater for the 3” gas lift pipeline and potable water for the 6” production 

pipeline. 

After completion of the production pipeline leak testing, the production pipeline will be 

dewatered and conditioned in preparation for the introduction of hydrocarbons. A Glycol slug 

propelled by nitrogen gas will be used for the dewatering and conditioning. The contents of 

the 6” production pipeline and pipeline spools will be discharged to the environment during 

the dewatering and conditioning operation. 

After completion of the 3” gas lift pipeline leak testing, the gas lift pipeline will be dewatered 

and conditioned in preparation for introduction of gas lift gas, using a glycol slug propelled by 

nitrogen gas. The contents of the gas lift pipeline and pipeline spools will be discharged to 

the environment during the bulk dewatering and conditioning operation. 

After completion of the (bulk) dewatering and conditioning operations and completion of the 

control / chemical injection system pre-commissioning and commissioning, the Bardolino field 

will be ready for start-up (introduction of hydrocarbons). During the start-up activities, the 

remaining pipeline pre-commissioning fluids will be displaced from the pipeline to the Nelson 

platform for processing. 

Details of all chemicals to be used and discharged during all phases of the pipeline 

installation, testing and commissioning activities will be submitted to BERR for approval in the 

PON 15C as required by the Offshore Chemical Regulations 2002. The PON 15C will 

include a detailed chemical risk assessment. 

3.5.6 Umbilical installation 

The umbilical will be installed by a DP vessel, and this will avoid the use of anchors and so 

prevent localised disruption to the seabed caused by the repeated placement and retrieval of 

anchors. The DP vessel will generate more emissions to atmosphere from power generation 

than an anchored vessel, but no anchor handling vessels will be required thereby reducing 

total emissions. The DP system may also create increased underwater noise, through the 

use of thrusters. The overall activity is planned to last only 30 days, however, and emissions 

and discharges during this time will be equivalent to those from normal shipping activities. 

Bridging documents between Shell and the installation contractors operating the pipeline 

installation vessels will describe the management structure and division of responsibilities that 

will prevail during the operations, the methodology for executing the work programme, and 

the emergency response procedures. 

The umbilical will be laid in a second, separate trench, located approximately 30 m from the 

export pipeline trench. The umbilical will be laid using one of several methods; at this stage 

of the project it is planned that the umbilical will be either: 

1. laid into a trench that is pre-cut by the pipeline plough and is subsequently allowed to 

infill naturally; or 

2. trenched using a jetting or cutting tool where the trench would infill over the umbilical 

during the trenching operation. 



The installation will be monitored in a post-lay inspection using a Remotely Operated Vehicle 

(ROV). The subsequent status of the umbilical, including any free spans, will be monitored in 

accordance with the Shell inspection and maintenance plans. There are no plans to rock 

dump the umbilical route, because this line will not contain export fluids and therefore would 

not be at risk from upheaval buckling or displacement. 

3.5.7 Umbilical pre-commissioning and testing 

For installation, the high pressure (HP) hydraulic, low pressure (LP) hydraulic and return 

cores in the umbilical will be filled with hydraulic fluid and all other cores will be filled with a 

glycol-water mixture. Similarly, the LP hydraulic and return cores in the Tree Supply Control 

Jumper (TSCJ) will be filled with hydraulic fluid and all other cores will be filled with a glycolwater 

mixture. 

After installation and tie-in of the umbilical and TSCJ, the umbilical and TSCJ cores will be 

subjected to a hydrostatic leak test to 1.1 times the design pressure for a period of 1 hour. 

The fluids used for the leak test will be those fluids in the equivalent, applicable Howe 

umbilical cores. These fluids may include corrosion inhibitor, scale inhibitor, wax inhibitor, 

methanol, hydraulic fluid and a glycol-water mixture. Some fluids may be discharged to the 

environment during the leak testing activities. 

The HP1 core in the umbilical and TSCJ will then be flushed with hydraulic fluid to displace 

the contents and allow function-testing of the control system. Some fluids may be discharged 

to the environment during the flushing activities. 

Finally, the chemical cores in the umbilical and TSCJ will be flushed with their applicable 

chemical to displace the contents. 

After completion of the control/chemical injection system pre-commissioning and 

commissioning, and completion of the pipeline system pre-commissioning and 

commissioning, the Bardolino field will be ready for start-up (introduction of hydrocarbons). 

During the start-up activities, the chemical injection pre-commissioning fluids will be displaced 

from the pipeline to the Nelson platform for processing. Details of all chemicals to be used 

and discharged during all phases of the pipeline installation, testing and commissioning 

activities will be submitted to the DTI for approval in the PON 15C as required by the 

Offshore Chemical Regulations 2002. The PON 15C will include a detailed chemical risk 

assessment. 

3.6 MODIFICATIONS AND COMMISSIONING OF EXISTING FACILITIES 

3.6.1 General platform description 

All produced fluids from Bardolino will be routed through the Howe production manifold and 

onwards to the Nelson platform for processing and export to shore. Partially stabilised crude 

oil and natural gas liquids (NGLs) are transported from Nelson through a 20” pipeline 25 km 

to the BP Forties system via the Forties Unity platform. Gas is transported from the platform 

through a 48 km 10” pipeline to the existing 20” gas pipeline from the Fulmar field and 

onwards to the St. Fergus gas terminal. 

The Howe reservoir is produced at a normal, nominal plateau production rate of 10,000 

barrels per day (bpd) with rates up to 15,000 (bpd) for short periods. Without the Bardolino 

development the Howe field life was expected to be about 8 years. 

The Nelson platform was designed to have a nominal capacity of 160,000 barrels of oil per 

day (stb/d) with 56 million standard cubic feet of gas per day (mmscf/d) for export. In 

addition, 12 million mmscf/d of gas is used as fuel gas. The platform provides single train 

separation, sand removal, oil metering and export facilities, gas compression for gas metering 

and export, and gas lift. 

The Nelson platform has a single oil processing train and a single gas compression train. The 

gas compressor is required for gas lift and gas export. The produced fluids from the wells 

flow via either a test or production manifold to their respective separators. The three phase 

(oil, gas and water) test separator enables individual wells to be tested on a regular basis, 

and the separated oil and water are recombined and then flow to the production separator. 



The production separation train consists of a single three-phase separator and a plate 

coalescer. 

3.6.2 Modifications to Howe infrastructure 

Minor modifications will be required to the Howe subsea infrastructure as a result of the 

Bardolino project. A new subsea electrical distribution box (EDB) and a new subsea valve 

skid will be installed at the Howe Pipeline Tie-in structure (PTS). A new regulator and 

associated valves will be fitted to the Howe hydraulic power unit (HPU). These modifications 

will entail the presence of a DP DSV at Howe for approximately 15 days during June 2009. 

The atmospheric emissions from these vessel operations have been calculated and are given 

in Table 3.6. 

3.6.3 Topsides Modifications at Nelson 

To accommodate the introduction of produced fluids from Bardolino it is necessary to add a 

H2S scavenger package to the Nelson topsides facilities. Work will involve the addition of an 

H2S scavenger storage and injection skid with associated pipe work and on-line analysers. 

This work on the topsides will be undertaken using normal supply vessel transport to Nelson 

and no additional vessel trips or days will be required. 

3.6.4 Production Start-up 

Production start-up plans are yet to be detailed. Initially, the well will be brought on-stream up 

to the choke valve in accordance with normal Shell well start-up procedures. 



3.7 PRODUCTION, UTILITY AND MAINTENANCE OPERATIONS 

3.7.1 Bardolino Production Profiles 

The Bardolino field will produce gas and oil over an expected field life of 10 years. Figure 

3.10 shows the forecasted high case (P10 or 10% likelihood of occurring), base case (P50 or 

50% likelihood of occurring) and low case (P90 or 90% likelihood of occurring) production 

profiles for Bardolino. 

The high case ultimate recovery for production from the Bardolino development well is 11.96 

billion scf of gas and 13,253 million bbls of oil. As the reservoir pressure declines throughout 

field life the gas oil ratio (GOR) is expected to increase. At the beginning of field life the GOR 

is expected to be 870 scf/stb, and this will increase to 1,599 scf/stb at the end of field life. 

Figure 3.10: Bardolino development production forecast 

Oil production (Mbbls/day) 

10000 

9000 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

0 

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 

3.7.2 Production Operations 

Field life (years) 

High case oil production 

Base case oil production 

Low case oil production 

High case gas production 

Base case gas production 

Low case gas production 

At present it is anticipated that bringing the Bardolino development on stream may result in 

some impacts to the operational performance of the Nelson platform. The addition of 

Bardolino fluids through the Nelson process may have an adverse impact on the amounts of 

dispersed oil in the produced water discharged at Nelson (discussed further in Section 3.7.3). 

In addition, the Bardolino development will increase the volume of the subsea system to 

Howe, which will extend the time taken for “blowdown” of the line (de-pressurisation of the 

system by venting of gas) when this is required for operational or maintenance reasons. 

3.7.3 Produced Water Handling 

Oil and gas extracted from North Sea reservoirs can contain substantial quantities of water, 

termed produced water. This water can arise from the original formation water, as well as 

from water injected into the reservoir to maintain reservoir pressure; the water is then 

extracted from the reservoir along with the oil and gas that is removed. Produced water 

contains small amounts of natural hydrocarbons, and may also contain traces of dissolved 

components such as metals and production chemicals. It must be treated to reduce the 

concentration of hydrocarbons to less than 30mg/l before discharge to the sea is permitted. 

At the Nelson platform, hydrocyclones and a produced water flash drum are used to separate 

produced water from oil and clean it, prior to its re-injection into the reservoir or disposal overboard. 

The Nelson platform was required to reduce the quantity of oil discharged to sea to 

meet the 2006 Oslo Paris Convention (OSPAR) agreement reductions. Produced Water Re- 

April 2008 Page 3-25 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Gas production (MMscf/day)


Injection (PWRI) facilities were thus added in 2006 to meet this requirement. Modifications 

were made to the produced water system and existing water injection facilities to allow 

produced water re-injection to the reservoir via 2 water injection wells. 

The forecasted produced water profiles associated with the high case (P10), base case (P50) 

and low case (P90) hydrocarbon production profiles for the Bardolino field are shown in 

Figure 3.11. 

Figure 3.11: Bardolino development produced water forecast 

Produced water rate (bbls/day) 

2500 

2000 

1500 

1000 

500 

0 

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 

Field life (years) 

High case produced water rate 

Base case produced water rate 

Low case produced water rate 

The Nelson platform currently processes an average of 150,000 stb of produced water each 

day. It is anticipated that the Bardolino development will impose an additional peak load of 

produced water at Nelson of 1,300 stb/d in 2010 for the base case profile. Bardolino water 

will therefore represent less than 1% of the total throughput currently handled at Nelson. 

Nelson currently re-injects approximately 140,000 stb/d of water and at peak rates 

approximately 165,000 stb/d could be handled by the production and separation facilities on 

the platform. The PWRI system currently operates at a 60% “up time” rate, i.e. it is 

operational for 60% of the time. Engineering work is under way to improve the “up time” of 

the Nelson PWRI facility from the current level of 60% to 80%. This work is due to be 

completed prior to the start up of the Bardolino field and will ensure that a greater proportion 

of the field’s produced water is re-injected into the reservoir, rather than being discharged to 

sea. Due to the additional quantities of produced water there will be a need to use additional 

quantities of Corrosion Inhibitor (CI) (see Section 3.7.5). CI is currently used at a level of 200 

ppmv on gross fluid production. CI is often observed to impair oil / water separation in 

produced water treatment systems, and therefore there is the potential for the amount of 

dispersed oil in discharged produced water at Nelson to increase as a result of the Bardolino 

development. The magnitude of any increase in the amount of dispersed oil in discharged 

produced water will depend on the quantity of fine solids in the produced fluids and the arrival 

temperature of the Bardolino fluids. The use of additional CI in combination with the fine 

solids that will be present in the Bardolino produced fluids has the potential to reduce the 

effectiveness of oil in produced water separation on Nelson, and thus increase the quantity of 

dispersed oil discharged to sea. Any increase in the amount of dispersed oil will be managed 

in accordance with the conditions of the Nelson permit under the Offshore Petroleum 

Activities (Oil Pollution Prevention and Control) (OPPC) Regulations 2005. 

The produced water from the Bardolino development would be treated by the existing 

produced water treatment system on the Nelson platform. Produced water would be treated 

so that at discharge the oil-in-water concentration of the produced water was well within the 

current BERR statutory limit of 30mg/l. Shell will monitor the impact on produced water 



quality from the increase in the quantity of corrosion inhibitor at Nelson to ensure that any 

impact is minimised. 

The concentration of oil in produced water will be routinely monitored at least twice a day, 

using the method approved by BERR, and will be reported through the UK Environmental 

Emissions Monitoring System (EEMS). 

3.7.4 Power Generation and Other Utilities 

The Bardolino development will not result in additional atmospheric emissions due to extra 

power generation on the Nelson platform. There is no requirement to install additional 

compressor plant at the Nelson platform, and it is not anticipated that any additional fuel gas 

will be used. The compressors at Nelson are currently running at their maximum rate and will 

continue to run at this rate following start up of production from Bardolino. 

3.7.5 Production Chemicals Usage 

Planned chemical use specific to the operations of the Bardolino development well will include 

the injection of Scale Inhibitor, Corrosion Inhibitor, Wax Inhibitor, Methanol and H2S 

Scavenger. The planned use of these specific chemicals are summarised in Table 3.8. 

Table 3.8: Production chemicals to be used for Bardolino 

Chemical 

Injection 

Location 

Scale Inhibitor Bardolino 

wellhead 

Corrosion 

Inhibitor 

Wax Inhibitor Howe PTS of 

Bardolino 

manifold 

Methanol Bardolino 

wellhead 

H 2S Scavenger Nelson 

(topsides) 

gas line 

Tie in Summary of intended use 

Existing Howe 

infrastructure 

(spare umbilical 

tube) 

Howe PTA Existing Howe 


Existing Howe 


Existing Howe 


New facilities 

required on 

Nelson 

To be injected continuously as water production 

commences at a dosage rate of 20 ppmv of 

Bardolino produced water. 

To be injected continuously at a dosage rate of 

200 ppmv of the combined total produced fluids 

from Bardolino and Howe. 

To be injected once the wellhead temperature 

has decreased (expected when the liquid 

production rate reaches ~ 2800 stb/d). WI is 

currently needed for Howe but co-mingling 

Bardolino and Howe fluids eliminates this 

requirement. As Howe production stops and 

Bardolino declines WI will be required again 

(estimated for 2014). No increase in the dosage 

or injection rate is foreseen, but Bardolino will 

extend the duration of WI use until 2019. 

Methanol will only be required for intermittent 

injection for well start up and shutdown. The 

increase in total Methanol use will be less than 

double the current rate used. 

H 2S Scavenger is required to reduce the level 

from 5 ppmv to 2.5 ppmv in produced gas. 

Appropriate topsides modifications will be made 

to the Nelson platform to accommodate this 

requirement. 

All additional production chemicals required for the Bardolino development will be added to 

the Nelson PON 15D which will be updated closer to the production start date. A full risk 

assessment of the use and discharge of the chemicals will be undertaken as part of this 

application. 

3.7.6 Waste 

Waste attributable to the Bardolino construction and operations (e.g. solids occasionally 

pigged from the pipeline, chemical drums), would be managed by the same means as 



existing waste is handled on the Nelson platform and in accordance with Shell’s Offshore 

Waste Disposal Procedures (Shell, 2005c). 

3.7.7 Accidental Discharge 

During the drilling of offshore wells, accidental spills can occur as a result of the release of 

reservoir fluids or drilling fluids. Spills may result from a well blow-out, a pipeline rupture or 

from a leakage of diesel or LTOBM from a support vessel. Spill prevention during drilling 

operations is therefore an important aspect of Shell’s EMS. 

Reporting of oil spills is a statutory requirement and the spill report data provide the most 

comprehensive data source available on spills from the UK offshore oil operations. All sizes 

of spill must be reported on a PON 1 and, as a result, the data set contains records that range 

from small spills of less than one litre to large spills of over 1,000 m 3 . 

Shell’s well engineering procedures are designed to ensure that drilling is carried out with 

minimum risk. Under extreme circumstances it is possible that the loss of well control could 

result in a blow-out, with an uncontrolled discharge of hydrocarbons to the environment. This 

is extremely rare, however, and there are many well-control measures and checking 

procedures in place to prevent such an event occurring. The primary method of well control is 

through the use of appropriately weighted drilling fluids (Section 3.4.6). Hydraulically 

operated valves or ‘blow out preventors’ (BOPs) provide a second line of defence in the event 

that the primary control is lost. Controls to prevent blow-outs are well developed and strictly 

applied, with the result that this is an extremely rare occurrence in the North Sea. Based on 

data given in the Exploration and Production (E&P) Forum database (which includes other 

areas as well as the North Sea), the probability of occurrence of blow-outs in development 

drilling is very low, 0.0016 per well drilled (i.e. about 2 in every 1,000 wells). With the 

hardware and procedural controls that will be in place during drilling activities for Bardolino 

the risk of such an event occurring is very low. The well design complies with Shell EPE 

Technical Standard (TS03) for Casing design and Shell EPE Technical Standard (TS04) for 

well control. 

A number of factors can result in spills of diesel, lubrication oil, drilling fluids and chemicals to 

sea from drilling rigs. Examples include failures of bunkering hoses and procedural failures in 

ensuring the containment integrity of storage tanks. In order to minimise the risk of such 

spills, the following controls are currently in place on mobile rigs contracted to Shell. 

All movements of drilling fluids to and from the rig are controlled by the rig’s “Permit to Work” 

System/Fluid Transfer Permits. All drain valves on drilling fluid storage tanks are locked in 

the closed position. These locks can only be removed once the fluids in the tank have been 

checked and the appropriate permit raised. 

All transfers of drilling mud, drilling fluid and diesel fuel to and from boats are carried out 

under observation of a dedicated crew member with instructions to halt operations 

immediately in the event of any spill or loss of containment. All rigs under contract to Shell 

are required to adhere to strict marine operating procedures which cover bunkering. 

Bunkering on location would only be undertaken in appropriate weather and visibility 

conditions. When LTOBMs are in use, all relevant drains are plugged to prevent spilt mud 

being lost to sea. Any mud spilt on board is recovered. 

Shell regularly reviews the technical and operational controls that are in place on rigs to 

ensure that the measures taken effectively minimise the probability of spills or other losses of 

containment. Reviews are regularly carried out and incorporated into HSE meetings with rig 

staff during drilling. 

The Bardolino development will be covered by the Nelson Field System Offshore Oil Spill 

Contingency Plan (3149-033). Response to spills is also specified in the Rig’s Emergency 

Procedures and in the Shell U.K. Limited general Oil Spill Contingency Plan ‘Oil Spill 

Response Procedures’ (3149-001). These procedures include the requirements of the 

Merchant Shipping (Oil Pollution Preparedness, Response and Co-operation 

Convention) Regulations 1998. 



3.7.8 Inspection and Maintenance Operations 

The subsea facilities will be designed so that they can be inspected, maintained and repaired 

in situ, as necessary. All key components of the production system would have a protection 

philosophy which will consider fishing activity, dropped objects, anchoring and simultaneous 

operations consistent with reducing safety and environmental risk within ‘as low as 

reasonably possible’ ALARP criteria. 

3.8 WELL ABANDONMENT AND DECOMMISSIONING 

In the unlikely event that the well is not deemed a success, it will be plugged and abandoned 

in accordance with Shell EPE Technical Standard (TS12) for Well Abandonment, which is 

based on UKOOA Guidelines. The well will be sealed with cement plugs and the casing cut 

in accordance with TS12, leaving no obstructions for fishing. 

Following drilling operations the operator has a duty to remove any industry-related debris 

from the seabed and to ensure that the seabed is clear. 

Decommissioning is not covered under the Offshore Petroleum Production and Pipe-lines 

(Assessment of Environmental Effects) Regulations 1999. The standards for the 

decommissioning of offshore structures are agreed internationally and implemented in 

national legislation. The Petroleum Act 1987 currently requires the submission of a 

Decommissioning Programme prior to the decommissioning and removal of offshore 

installations from UK waters. 

Final decommissioning of the Bardolino infrastructure will be undertaken in full accordance 

with legislation in force at the date of decommissioning. 



4 ENVIRONMENTAL DESCRIPTION 


The proposed Bardolino development is located in Blocks 22/11, 22/12 and 22/13 in the 

central North Sea. The proposed Bardolino well location would be situated approximately 3 

km east of the Howe development in Block 22/12 and 17 km east of the Nelson production 

platform in Block 22/11 (Figure 4.1). Peterhead, the nearest coastal location to the Bardolino 

development is 190 km to the west, and the UK/Netherlands median line is 40 km to the east 

of the proposed development. 

Figure 4.1 Location of the Bardolino development 

4.2 OFFSHORE PHYSICAL AND CHEMICAL ENVIRONMENT 

The physical conditions of the environment influence the type and distribution of marine life in 

the area, determine some of the design parameters for offshore facilities and influence the 

behaviour of emissions and discharges (including spills) from offshore facilities. 

4.2.1 Bathymetry 

Water depth in the UK central North Sea varies between 50 m and 100 m. The seabed 

topography at the development area is generally smooth with very little gradient. The water 

depths in the development area range from 85 m to 91 m LAT (lowest astronomical tide), and 

the water depth at the proposed Bardolino well location is 91 m LAT. Figure 4.2 illustrates 

the seabed bathymetry between the proposed Bardolino well and the Howe subsea manifold 

(Gardline Geosurvey Limited 2007). 

April 2008 Page 4-1


Figure 4.2 Bardolino bathymetry 

Page 4-2 April 2008


Water masses, currents and tidal streams 

The major water masses in the North Sea can be classified as Atlantic water, Scottish coastal 

water, northern North Sea water, Norwegian coastal water, central North Sea water, southern 

North Sea water, Jutland coastal water and Channel water (Turrell et al., 1992). The 

proposed Bardolino development is located in the area influenced by the northern North Sea 

water mass (Figure 4.3). 

Circulation in the North Sea is driven by a combination of winds, tidal forcing and 

topographically-steered inflows. The predominant regional current in the central North Sea 

originates from the vertically well-mixed coastal water and Atlantic Water inflow of the Fair Isle 

/ Dooley Current, which flows around the north of the Orkney Islands and into the North Sea 

(Figure 4.3). The background, or residual, flow in the central North Sea (associated with 

North Sea circulation patterns) is typically 0.2 m/s towards the south (DTI, 2001). 

The generalised pattern of water movement in the North Sea may be strongly influenced by 

short-medium term weather conditions, resulting in considerable seasonal and annual 

variability. 

Semi-diurnal tidal currents are relatively weak in the offshore northern and central North Sea 

(DTI, 2001). In the area of the proposed development the maximum tidal current speed 

during mean spring tides is between 0.26 m/s and 0.39 m/s (0.5-0.75 knots) (UKDMAP, 

1998). Surge and wind-driven currents, caused by changes in atmospheric conditions, can 

be much stronger and are generally more severe during winter. Storm events may also 

generate near-bed, wave-induced currents sufficient to cause sediment mobilisation (DTI, 

2001). The maximum 50 year surge current at the proposed development site is about 0.6 

m/s (UKDMAP, 1998). 

The speed and direction of water currents have a direct effect on the transport, dispersion and 

ultimate fate of any discharges from an installation; in regions where strong directional water 

currents occur, greater dispersal of discharges will take place. Mixing in the water column 

intensifies with increased current speed. Currents in the area around the Bardolino 

development will consist of tidal currents combined with non-tidal flows, as a result of 

background circulation, surges, local wind action and thermohaline effects. Current speeds 

decrease with proximity to the seabed, often becoming weak and variable. Table 4.1 

indicates the current profile for the development area. 

Table 4.1 Current profile (m/s) for the development area 

Current (m/s) 1-Year 5-Year 10-Year 50-Year 

Sea surface 0.75 to 0.83 0.80 to 0.90 0.81 to 0.92 0.88 to 0.98 

Near seabed 0.43 to 0.48 0.46 to 0.51 0.46 to 0.52 0.50 to 0.56 

Source: Shell (2008) 

April 2008 Page 4-3


Figure 4.3 Bathymetry and currents in the area of the Bardolino development 

Waves are generated when wind acts on the sea surface. Wave size is related to wind 

intensity, duration, and the distance or fetch over which the wind blows. The wave climate of 

the North Sea has changed in recent years, with a tendency towards increasing wave height 

(Anatec UK Ltd., 2001). In area of the proposed Bardolino development the storm surge 

elevation with a return period of 50 years is approximately 1.0 - 1.25 m (UKDMAP, 1998). 

During storms, the re-suspension and vertical dispersion of bottom sediments due to waves 

and currents affects most of the North Sea. 

Wave conditions in the central North Sea vary from calm to severe, depending on the wind 

strength and direction. Wave data for the development are given in Table 4.2. 

Table 4.2 Wave data (height and period) for the Bardolino development area 

Waves 1-Year 5-Year 10-Year 50-Year 

Wave height (m) 

Hs - significant wave height (3-hr) 9.5 10.9 11.5 12.8 

Hmax - maximum wave height (3-hr) 17.7 20.2 21.3 23.6 

Wave period (s) 

Tz – period associated with Hs 9.8 10.5 10.8 11.4 

Tass- period associated with Hmax 12.5 13.4 13.8 14.6 


The tidal range in the central North Sea varies significantly from 3-4 m in the west to less than 

1 m in the east. Tidal ranges for the development area are given in Table 4.3. 

Page 4-4 April 2008


Table 4.3 Tidal ranges for the Bardolino development area 

Tidal Height Water levels in metres (relative to LAT) 

Highest Astronomical Tide (HAT) 1.39 to 1.65 

Mean High Water Spring (MHWS) 1.25 to 1.47 

¾ Tide (¾(MHW-MSL)) 1.02 to 1.20 

Mean High Water Neaps (MHWN) 0.99 to 1.17 

Mean Sea level (MSL) 0.73 to 0.85 

Mean Low Water Neaps (MLWN) 0.46 to 0.55 

Mean Low Water Spring (MLWS) 0.17 to 0.20 

Lowest Astronomical Tide (LAT) 0.00 

1-Year 5-Year 10-Year 50-Year 

Positive surge levels (MSL) 1.04 1.22 1.30 1.49 

Negative surge levels (MSL) -0.62 to -0.69 -0.74 to -0.84 -0.80 to -0.90 -0.92 to -1.03 


4.2.2 Meteorology 

The North Sea is situated in temperate latitudes with a climate that is strongly influenced by 

the inflow of oceanic water from the Atlantic Ocean, and by the large-scale westerly air 

circulation which frequently contains low-pressure systems. As a result, the North Sea 

climate is characterised by large variations in wind direction and speed, frequent cloud and 

relatively high precipitation. 

Wind speed and direction directly influence the transport and dispersion of atmospheric 

emissions from an installation. These factors are also important for the dispersion of marine 

emissions, including oil spills, by affecting the movement, direction and break up of 

substances on the sea surface. 

Historical wind data collected from the Forties Main Dataset (Block 21/10) over a 28 year 

period (1974-2002; Shell, 2003) provides an indication of the expected wind regime at the 

proposed Bardolino development area, which lies approximately 30 km to the north-west. 

These data indicate that wind speed and direction are variable throughout the year. Between 

September and February, winds predominantly originate from south-westerly directions, 

whereas winds originating from a north-westerly direction predominate between March and 

August. Predominant wind speeds in the development area range between 8 to 14 m/s (fresh 

to strong breezes), but during spring (April to July) wind speeds range from 0 to 6 m/s (light 

air to gentle breeze). Strong winds (winds exceeding 14 m/s) occur most frequently during 

the winter months (September to March). Figure 4.4 shows the annual windrose for the 

proposed development area, based on the Forties Main Dataset. 

The highest winds (greater then 14 m/s) occur from the south and south-west, although the 

most severe wind speeds come from the north-west. The maximum hourly mean wind speed 

with an average recurrence of 50 years is approximately 37 m/s (UKDMAP, 1998). 

April 2008 Page 4-5


Figure 4.4 Annual windrose for the central North Sea 


4.2.3 Sea temperature and salinity 

The temperature of the sea affects both the properties of the seawater and the fates of 

discharges and spills to the environment. Temperature is also important in determining the 

distribution and occurrence of marine organisms. Table 4.4 shows the typical air, sea surface 

and seabed temperatures for the proposed development area based on 100-year returns. 

In comparison to air temperatures, sea surface temperatures change slowly with little 

variation from day to day. The mean sea surface temperature in the area of the proposed 

development ranges from around 14.5 o C to 15 o C during summer to between 5 o C and 6 o C 

during the winter. The mean seabed temperature ranges from 7 o C to 8 o C during summer and 

between 6.5 o C and 7 o C during winter (UKDMAP, 1998). 

Table 4.4 Temperature (ºC) profiles for the Bardolino development area 

Minimum (100-year) Maximum (100-year) 

Air temperatures (ºC) -8.2 24.5 

Sea surface temperatures (ºC) 1.0 21.0 

Seabed temperatures (ºC) 4.0 11.0 


From January to mid-May, the water in the central North Sea is well mixed, with temperatures 

constant throughout the depth of the water column. At the end of May, the water column 

begins to stratify due to increased solar radiation and calmer conditions, and this results in the 

formation of a warm surface layer of 20 to 40 m depth above the cooler bottom layer. These 

two layers are separated by a thermocline, a region with a pronounced vertical temperature 

gradient. This stratification begins to break down in late August / early September due to 

decreasing solar heating and increasing wind and wave action. 

Fluctuations in salinity are largely caused by the addition or removal of water through natural 

processes such as rainfall and evaporation. Salinity varies with season and changes in 

ocean currents. 

Page 4-6 April 2008


Salinity in the waters around the Bardolino development shows little seasonal variation, with 

mean seabed salinities ranging from 35 ppt in winter to 35.2 ppt in summer, and mean sea 

surface salinities ranging between 35.2 ppt in winter and 35 ppt in summer (UKDMAP, 1998). 

4.2.4 Water quality 

The North Sea Quality Status Reports (NSTF, 1993; 2000) state that, although the waters of 

the northern North Sea as a whole do not contain contamination above normal background 

levels, slightly higher levels of contamination are typically found in the shallower southern 

North Sea. 

In the North Sea, water samples with the highest levels of chemical contamination are 

generally found at inshore estuary and coastal sites subject to high industrial usage (Table 

4.5). Where concentrations of total hydrocarbons (THCs) are found to be high offshore, these 

are in the immediate vicinity of installations, and concentrations generally fall to background 

levels within a very short distance of the point of discharge (CEFAS, 2001a). 

Table 4.5 Summary of contaminant levels typically found in surface waters of the 

North Sea 

Location THC 

(µg/l) 

Oil & Gas 

Installations 

PAH 

(µg/l) 

PCB 

(ng/l) 

Ni 

(µg/l) 

Cu 

(µg/l) 

Zn 

(µg/l) 

Cd 

(ng/l) 

Hg 

(ng/l) 

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 

Offshore 0.5-0.7


sediment or organic matters is poorly understood, but in general terms prolonged contact 

between hydrocarbons and sediment may result in stronger bond formation and a subsequent 

reduction in bioavailability (van Brummelen et al., 1998). This phenomenon is referred to as 

‘ageing’, and is especially important for sediments with historic contamination such as 

prolonged discharge of drill cuttings. 

The distribution of seabed sediments within the central North Sea results from a combination 

of hydrographic conditions, bathymetry and sediment supply. Sediments classified as sand 

and slightly gravelly sand cover approximately 80 % of the central North Sea (Gatliff et al., 

1994). These sandy sediments occur over a wide range of water depths, from the shallow 

coastal zone down to about 110 m in the north and to below 120 m in isolated depths to the 

south and west. The carbonate content of the sand fraction is generally less than 10 % 

(Gatliff et al., 1994). 

A 3 km by 3 km anchoring conditions survey was undertaken for the Bardolino development 

in Block 22/13, centring on the Bardolino well location and also including the areas around the 

existing Howe manifold so as to encompass the proposed Bardolino to Howe pipeline route. 

The survey indicated that seabed sediments comprise a veneer of sand with outcrops of clay 

and scattered cobbles and small boulders (Gardline Geosurvey Limited, 2007). The shallow 

soils throughout the Bardolino area comprise soft to firm slightly sandy clay with occasional 

gravel (Coal Pit Formation), ranging from 25 m thickness in the west to being locally absent in 

the east (Gardline Geosurvey Limited, 2007). In the west and north-west of the survey area, 

several well-defined channel-like features sub-crop the seabed. The channel infill sediments 

are expected to comprise firm to stiff silty sandy clay with occasional sand (Forth/Coal Pit 

Formations). 

No shallow gas accumulations representing a potential hazard to drilling operations were 

detected during a 1 km by 1 km shallow geohazard survey centred on the proposed Bardolino 

well location (Gardline Geosurvey Limited, 2007). Several seabed objects were identified 

within the survey area, the majority of which are expected to be boulders. The closest 

significant boulder to the proposed Bardolino well site occurs 15 m to the southeast and is 0.5 

m high (Gardline Geosurvey Limited, 2007). 

A 3 km by 3 km rig site survey and a pipeline route survey undertaken in Block 22/12a for a 

suspended alternative development project indicated that seabed sediments comprise a 

veneer of sand with shell fragments (


Figure 4.5 Location of Nelson platform sampling stations 

4.2.6 Sediment chemistry 

Trends in the concentration and distribution of contaminants in North Sea sediments, 

particularly hydrocarbons (HCs), are similar to those described for surface water 

contamination (Table 4.6). There are, however, some notable exceptions. For example, the 

concentrations of certain metals appear higher in the southern North Sea compared to the 

northern North Sea (e.g. Pb, V, Cu and Fe). Work on seasonal current circulation patterns 

within the southern North Sea suggests that this may be due to coastal contamination 

transported offshore without being widely dispersed (CEFAS, 2001a). 

April 2008 Page 4-9


Table 4.6 Summary of contaminant concentrations typically found in surface 

sediments from the North Sea 

Location THC PAH PCB Ni Cu Zn Cd Hg 

Estuaries 

- 0.2-28 

Concentration (µg/g) 

6.8 - 

19.1 

- - - - - 

Coast - - 2 - - - - - 

Offshore 17 - 20 0.2-2.7


Total hydrocarbon concentrations (THCs) at sample stations more than 500 m from the 

Nelson platform station were found to be below the contaminant levels typically found in 

surface sediments in an offshore location in the North Sea (Table 4.7). Metal analysis 

indicated that heavy metal concentrations at the seabed sample locations more than 500 m 

from the Nelson platform were below the contaminant levels typically found in surface 

sediments in an offshore location of the North Sea. 

4.3 OFFSHORE CONSERVATION AREAS 

The European Community (EC) Directive 92/43/EEC on the Conservation of Natural Habitats 

and of Wild Flora and Fauna (the Habitats Directive), and the EC Directive 79/409/EEC on the 

Conservation of Wild Birds (the Birds Directive), are the main instruments of the European 

Union (EU) for safeguarding biodiversity. 

These Directives provide for the protection of animal and plant species of European 

importance and the habitats which support them, particularly through the establishment of a 

network of protected sites. The Habitats Directive includes a requirement to establish a 

European network of important high quality conservation sites that will make a significant 

contribution to conserving the habitat and species identified in Annexes I and II of the 

Directive. Habitat types and species listed in Annexes I and II are those considered to be in 

most need of conservation at a European level (JNCC, 2002, 2008). 

The UK government, with guidance from the Joint Nature Conservation Committee (JNCC) 

and the Department of Environment, Food and Rural Affairs (Defra), has statutory jurisdiction 

under the EC Habitats Directive to propose offshore areas or species (based on the habitat 

types and species identified in Annexes I and II) to be designated as Special Areas of 

Conservation (SAC). These designations have not yet been finalised, but will be made to 

ensure that the biodiversity of the area is maintained through conservation of important, rare 

or threatened species and habitats of certain species. 

Special Areas of Conservation (SACs) are sites that have been adopted by the European 

Commission and formally designated by the government of each country in whose territory 

the site lies. Sites of Community Importance (SCIs) are sites that have been adopted by the 

European Commission but not yet formally designated by the government of each country. 

Candidate SACs (cSACs) are sites that have been submitted to the European Commission, 

but not yet formally adopted. Candidate SACs will be considered in the same way as if they 

had already been classified or designated, and any activity likely to have a significant effect 

on a site must be appropriately assessed. Possible SACs (pSACs) are sites that have been 

formally advised to UK Government, but not yet submitted to the European Commission. 

Draft SACs (dSACs) are areas that have been formally advised to UK government as suitable 

for selection as SACs, but have not been formally approved by government as sites for public 

consultation (JNCC, 2008). 

In relation to UK offshore waters, four habitats from Annex I and four species from Annex II of 

the Habitats Directive are currently under consideration for the identification of SACs in UK 

offshore waters (JNCC, 2002, 2008; Table 4.8). Currently in UK offshore waters there are no 

SACs, cSACs or SCIs; there are seven possible SACs and one draft offshore site that have 

not yet been submitted to the European Commission (Table 4.9; JNCC, 2008). 



Table 4.8 Annex I Habitats and Annex II Species occurring in UK offshore waters 

Annex I habitats considered for SAC selection in 

UK offshore waters 

� Sandbanks which are slightly covered by seawater all the 

time 

� Reefs (bedrock, biogenic and stony) 

− Bedrock reefs – made from continuous outcroppings 

of bedrock which may be of various topographical 

shape (e.g. pinnacles, offshore banks); 

− Stony reefs – these consist of aggregations of 

boulders and cobbles which may have some finer 

sediments in interstitial spaces (e.g. cobble and 

boulder reefs, iceberg ploughmarks); and 

− Biogenic reefs – formed by cold water corals (e.g. 

Lophelia pertusa) and the polychaete worm Sabellaria 

spinulosa. 

� Submarine structure made by leaking gases 

� Submerged or partially submerged sea caves 

Source: JNCC (2002, 2008) 

Species listed in Annex II 

known to occur in UK 

offshore waters 

� Grey seal 

(Halichoerus grypus) 

� Harbour or common seal (Phoca 

vitulina) 

� Bottlenose dolphin (Tursiops 

truncatus) 

� Harbour porpoise (Phocoena 

phocoena) 

The Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 

(Amended 2007) apply the Habitats Directive and Birds Directive in relation to oil and gas 

plans or projects wholly or partly on the United Kingdom’s Continental Shelf (UKCS) and 

adjacent waters outside territorial waters. These regulations extend to the seaward limits of 

territorial waters (12 nm offshore) (BERR, 2008). The Offshore Marine Conservation 

(Natural Habitats, &c.) Regulations 2007 came into force in August 2007. These 

regulations transpose the Habitats Directive and Birds Directive in the marine offshore area, 

from 12 nm to 200 nm from the UK coast. Under these new regulations it is an offence to 

deliberately capture, injure or kill any wild bird or any wild animal of a European Protected 

Species (EPS); and/or significantly disturb any EPS in such a way as to significantly affect (i) 

the ability of any significant group of animals to survive, breed, rear or nurture their young; or 

(ii) the local distribution or abundance of that species. EPS include all species of cetaceans 

(whales, dolphins and porpoises), all species of marine turtles, the sturgeon (Acipenser sturio) 

and the otter (Lutra lutra) (DEFRA, 2008; JNCC, 2007a). 



Table 4.9 Possible and draft Special Area of Conservation (SAC) in UK offshore 

waters 

Name Description Location Site 

Location 

Braemar 

Pockmarks 

Darwin Mounds 

Dogger Bank 

Haig Fras 

North Norfolk 

Sandbanks and 

Saturn Sabellaria 

spinulosa reef 

Scanner 

Pockmark 

Submarine structures 

made by leaking gas 

Northern 

North Sea 

Cold water corals NW Scotland, 

Atlantic Ocean 

Large sublittoral sand 

bank 

Submarine, isolated 

bedrock outcrop 

Sandbanks, seldom 

covered by more than 

20m water. Biogenic 

reef consisting of 

colonies of polychaete 

worms 

Shallow depression 

approx. 600m by 300m 

and 20m deep 

Stanton Banks Bedrock reef 

Wyville Thomson 

Ridge 

Transition area 

between two 

biogeographic areas. 

Southern 

North Sea 

Celtic Sea 

Southern 

North Sea 

Northern 

North Sea 

West of 

Scotland, 


NW Scotland, 


58.99 o N, 

1.48 o E 

59.76 o N, 

7.22 o W 

54.81 o N , 

2.12 o E 

50.26 o N, 

7.78 o W 

53.34 o N, 

2.13 o E 

58.28 o N, 

0.97 o E 

56.24 o N, 

7.94 o W 

59.98 o N, 

6.72 o W 

Area 

(km 2 ) 

Status 

21.34 pSAC 

1,377 pSAC 

13,405 dSAC 

757 pSAC 

4,327 pSAC 

7.25 pSAC 

1,745 pSAC 

1,740 pSAC 

*all possible (pSAC) and draft (dSAC) boundaries are subject to confirmation; therefore the site centre 

location and area are provisional and give only a general indication of the pSACs/dSACs. 

Source: JNCC (2007b, 2008) 

4.3.1 Annex I Habitats 

Sandbanks 

“Sandbanks which are slightly covered by sea water all the time” consist of sandy sediments 

that are permanently covered by sea water. Water depth above sandbanks is seldom more 

than 20 m below chart datum, but some sandbanks may extend into deeper waters. 

Sandbanks can be classified topographically (for example, those associated with headlands, 

the open shelf or estuary mouths) or by sediment type (for example, gravelly and clean 

sands, or muddy sands) (JNCC, 2007b). 

Shallow sandbanks may support vegetation, such as eelgrass or maerl, but this is less 

common in waters away from the coast. Organisms found on and in shallow sandbanks 

include a variety of worms, crustaceans, molluscs, urchins, starfish and crabs. Sandy 

habitats can be important as nursery areas for a variety of fish species. They also act as 

feeding grounds for seabirds, seals and cetaceans, by providing a source of sandeels and 

other prey species (JNCC, 2007b). 

Sandbanks are very large bedforms which are characteristic of tide-dominated continental 

shelves. The southern North Sea includes some of the best known examples of continental 

shelf sandbanks (BGS, 2002). The four main groups of sandbanks in the southern North Sea 

are the East Bank Ridges, the Sand Hills, the Norfolk Banks and the Wash (BGS, 2002). The 

Norfolk Banks are the best known group of sandbanks and lie off the coast of north east 

Norfolk. The banks are sub-parallel to the modern coastline and, at the southern end of the 

group sandbanks may be connected to the shore (BGS, 2002). 



Reefs 

Annex I reef habitats are defined as "submarine, or exposed at low tide, rocky substrates and 

biogenic concretions, which arise from the seafloor in the sublittoral zone but may extend in to 

the littoral zone where there is an uninterrupted zonation of plant and animal communities”. 

These reefs generally support a zonation of benthic communities of algae and animal species 

including concretions, encrustations and corallogenic concretions" (EC, 2003). The UK has 

interpreted the habitat further to include bedrock, boulders and cobbles (generally >64mm in 

diameter), including those composed of soft rock, e.g. chalk. Aggregations of species that 

form a hard substratum (biogenic concretions) which enable an epibiotic community to 

develop are also considered in this habitat category. 

Reefs are very variable in form and in the communities that they support. Two main types of 

reef can be recognised; those where animal and plant communities develop on rock or stable 

boulders and cobbles, and those where structure is created by the animals themselves 

(biogenic reefs). Reef habitats occur offshore in the English Channel, Celtic Sea, Irish Sea, 

and to the west and north of Scotland extending far out into the North Atlantic (JNCC, 2002). 

Submerged sea caves 

Submerged or partially submerged sea caves are widely distributed in inshore waters, but no 

examples are currently known offshore (i.e. between 12 nm and 200 nm from the UK coast) 

(JNCC, 2002). 

Submarine structures made by leaking gases 

‘Submarine structures made by leaking gases’ in Annex I are defined as "spectacular 

submarine complex structures, consisting of rocks, pavements and pillars up to 4 m high. 

These formations are due to the aggregation of sandstone by carbonate cement resulting 

from microbial oxidation of gas emissions, mainly methane. The methane most likely 

originated from the microbial decomposition of fossil plant materials. The formations are 

interspersed with gas vents that intermittently release gas. These formations shelter a highly 

diversified ecosystem with brightly coloured species" (EC, 2003). 

'Marine columns' (the name of this habitat in the original Habitats Directive Annex I), such as 

those found in Danish waters (see Jensen et al., 1992), are not known to occur in UK waters. 

However, gas seep depressions (commonly referred to as 'pockmarks'), some of which have 

carbonate structures associated within them, do occur in UK waters. Therefore it remains to 

be determined whether those 'pockmarks' with carbonate structures fit within the Annex I 

habitat definition for ‘submarine structures made by leaking gases, and sites may be selected 

for this habitat type. However, if on further investigation the 'pockmarks' with carbonate 

structures are not deemed to be 'spectacular submarine complex structures', then this habitat 

will not be represented in UK offshore waters (JNCC, 2002). 

Pockmarks 

Pockmarks are shallow seabed depressions and they are generally formed in soft, finegrained 

seabed sediments (Judd, 2001). In the North Sea, pockmarks range from less than 

0.5 m to approximately 20 m in depth, and from 1 m to more than 1,000 m in length. Most 

pockmarks are relict features but a few continue to leak natural gas and may contain 

carbonate structures (Methane Derived Authigenic Carbonate (MDAC)) which provide a 

habitat for encrusting and other surface-living seabed animals (DTI, 2001). 

Pockmarks alone are not considered to conform to any of the Annex I habitats, but the 

potentially important ‘submarine structures’ listed in Annex I are often associated with gas 

seeps and pockmarks. While MDAC concretions provide evidence of historical gas seeps, in 

the absence of bubbles or sulphate reducing bacterial mats they are not indicative of active 

gas seeps (Judd, 2001). Most North Sea pockmarks are shallow and currently inactive. 

Continuous or recent activity, with or without MDAC, is thought to be confined to unusually 

large pockmarks (Dando, 2001). 



In the North Sea the majority of pockmarks have been found in the sediments of the Witch 

Ground Formation (in the central/northern North Sea depression known as the Witch Ground 

Basin) and their equivalents, the Flags Formation (which occupies hollows in the northern 

North Sea plateau) (Judd, 2001). 

The proposed Bardolino development is located outside the Witch Ground and any known 

gas seep areas. The Scanner Pockmark (dSAC) in Block 15/25 and Braemar Pockmarks 

(dSAC) in Block 16/3 are located approximately 67 km and 146 km respectively from the 

proposed development site (DTI, 2001; JNCC, 2008; Figure 4.6). No pockmarks were 

identified during the anchor conditions survey (Gardline Geosurvey Limited 2007). 

Figure 4.6 Location of the proposed Bardolino development site in relation to gas 

seep areas, the Scanner Pockmark, and the Braemar Pockmarks 

4.3.2 Annex II Species 

Annex II Species are defined as “species of community interest whose conservation requires 

the designation of Special Areas of Conservation (SAC)”. There are four species listed on 

Annex II of the Habitats Directive known to occur in UK waters for which selection of offshore 

SACs will be considered; grey seal, common or harbour seal, bottlenose dolphin and harbour 

porpoise (Table 4.10). As with all marine mammals, the four species can be impacted by a 

number of effects associated with the activities of the offshore oil and gas industry, such as 

underwater noise, chemical contaminants, oil spills, and any effects on prey availability 

(SMRU, 2001). 

For the two seal species, coastal SACs have already been designated in the UK to protect 

breeding colonies and their moulting and haul-out sites. Two coastal SACs have been 

designated for bottlenose dolphins within UK territorial waters. The UK currently has no 

proposed SACs for harbour porpoise. The four species are typically wide-ranging, so it is 

difficult to identify specific areas which may be deemed essential to their life and reproduction, 



and which may, therefore, be considered for proposal as SACs (JNCC, 2002). Relevant 

information on the distribution of Annex II species in UK offshore waters is limited. Further 

analysis of data, and in some cases further survey, will be required to identify any areas in UK 

waters away from the coast which may qualify as SACs for these species (JNCC, 2002). 

Grey seals 

Grey seals spend most of the year at sea and may range widely in search of prey. 

Information on the distribution of British grey seals at sea, although limited, shows that they 

do occur offshore in SEA-2 UKCS Blocks; the population as a whole, however, does not 

appear to spend significant time in these offshore areas (SMRU, 2001). There are pupping 

sites on many coasts between the Isles of Scilly in the south-west, clockwise round to Donna 

Nook in Lincolnshire. These rookeries vary greatly in size with the largest being in the Inner 

and Outer Hebrides, Orkney, Isle of May, Farne Islands and Donna Nook (JNCC, 2008). 

Designated coastal SAC sites include Faray and Holm of Faray on Orkney and the Isle of 

May. 

Grey seals may be present in the area of the proposed development as they travel between 

sites and to and from foraging areas, but their occurrence is likely to be low as the site is 

located over 190 km from shore. 

Harbour or common seals 

Data on the distribution of harbour seals at sea is even sparser than that for grey seals. 

Studies suggest, however, that they have a more inshore distribution at sea than do grey 

seals, and tend to forage within 75 km of haul-out sites (JNCC, 2002). It is highly unlikely, 

therefore, that harbour seals forage in the central and northern offshore SEA-2 UKCS Blocks, 

including the area of the proposed development (SMRU, 2001). 

Harbour seals are widespread around the shores of the UK but population density varies 

greatly from place to place, and numbers are low at many sites. Harbour seals are found 

from Northern Ireland and the southern Firth of Clyde clockwise round the coast to the 

Thames estuary. The vast majority of harbour seal haul-out sites are found around the coasts 

of Scotland (JNCC, 2008). Designated coastal SACs sites include Yell Sound and Mousa on 

Shetland, Sanday on Orkney and the Dornoch Firth and Morrich More (JNCC, 2008). 

Bottlenose dolphins 

There are two main areas of UK territorial waters - Cardigan Bay and the Moray Firth - where 

there are semi-resident groups of bottlenose dolphin, and both have been designated SACs 

for bottlenose dolphins. There are also smaller populations of dolphins off south Dorset, 

around Cornwall and in the Sound of Barra in the Outer Hebrides. Dolphins from all of these 

areas may occasionally move some distance from their apparent core range. For example, 

regular sightings in the Firth of Forth probably involve dolphins from the Moray Firth. Other 

dolphin groups, presumed to be of transients, are recorded further offshore in deeper water to 

the west of Scotland (JNCC, 2008). 

In the North Sea, bottlenose dolphins are most frequently sighted within 10 km of land and 

they are rarely sighted outside coastal waters. It is possible, however, that some inshore 

dolphins move offshore during the winter months. For example, in the Moray Firth the 

population of dolphins is estimated to consist of approximately 129 individuals (95% 

confidence interval 110–174). Although these dolphins are considered to be resident in the 

inner Moray Firth, numbers decrease during winter (Wilson et al., 1997). Because sightings 

elsewhere around the coast do not increase accordingly, it is possible that animals from this 

population move offshore at this time of year (SMRU, 2001). Therefore it is possible that 

bottlenose dolphins may be present in the area of the proposed development, although 

numbers are likely to be low and occurrence infrequent (see Section 4.4.4). 

Harbour porpoises 

Of the Annex II species listed in Table 4.10, the only species recorded within the proposed 

development area is the harbour porpoise. Sightings have been recorded in UKCS Blocks 

22/11, 22/12 and 22/13 during July and in surrounding blocks during June and July, although 



there were no data available for January, March, May, June, October and November (Table 

4.10; UKDMAP, 1998). Harbour porpoises are present throughout most of the North Sea 

throughout the year, with higher numbers occurring between May and October (Section 

4.4.4). Proposed development activities are scheduled to occur between March and August 

2009 (Section 3.3.2). 

Table 4.10 : Recorded sightings of harbour porpoises in the vicinity of the Bardolino 

development [Months in yellow indicate the proposed development schedule] 

Block Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

22/6 

22/7 

22/8 

22/9 

22/11 

22/12 

22/13 

22/14 

22/16 

22/17 

22/18 

22/19 

KEY High numbers (0.20-0.49/km) 

Moderate numbers (0.10-0.19/km) 

Low numbers (0.01-0.09/km) 

None 

Source: UKDMAP (1998) 

No data available 

The harbour porpoise is widespread throughout the cold and temperate seas of north-west 

Europe, including the North Sea, the Skagerrak, Kattegat, Irish Sea, the seas west of Ireland 

and Scotland, northwards to Orkney and Shetland and off the coasts of Norway (Jackson & 

McLeod, 2002). Harbour porpoises are highly mobile and well-distributed around the UK, with 

the exception of the English Channel and south-east of England (Reid et al., 2003). Numbers 

of harbour porpoise in the southern North Sea declined during the twentieth century, but there 

is evidence of recent return to the area, for example Camphuysen (2004) and Thomsen et al. 

(2006). In the North Sea, sightings from shipboard and aerial surveys indicate that harbour 

porpoises are widely and almost continuously distributed, with important concentrations in the 

central North Sea, along the Danish and northern German coasts (Donovan & Bjørge, 1995; 

Hammond et al., 2002; IWC, 1996). 

The seasonal movements and migratory patterns of harbour porpoises in the North East 

Atlantic and North Sea are not well understood. Porpoises may reside within an area for an 

extended period of time, but onshore/offshore migrations and movements parallel to the shore 

are thought to occur (Bjørge & Tolley, 2002). In the North Sea, there may be a general 

westward movement from the eastern North Sea and possibly from the very northern areas of 

the North Sea into the western edge of the northern North Sea (along the east coast of 

Scotland) during April to June and a further influx to the northern North Sea during July to 

September (Northridge et al., 1995). These seasonal movements are thought to coincide with 

the calving and mating seasons, respectively. 

At present, not enough is known about harbour porpoises to determine whether some parts of 

their range are more important for breeding than others. Potential calving grounds have been 

identified in the German North Sea (Sonntag et al., 1999), but there is currently no evidence 

of specific habitat requirements for mating and calving in UK waters (JNCC, 2002). Although 

the UK currently has no proposed SACs for harbour porpoises, the UK Government is re- 



examining distribution data for this species in inshore and offshore waters in an attempt to 

identify likely areas as SACs, taking into account: 

• the continuous or regular presence of the species (subject to seasonal variations); 

• good population density (in relation to neighbouring areas); and 

• high ratio of young to adults during certain periods of the year (JNCC, 2002). 

There is limited information available on the overall distribution and abundance of this species 

in UK waters. The estimated summer abundance of harbour porpoises in North Sea areas 

during the SCANS (small cetacean abundance in the North Sea) survey in July 1994 was 

268,452 (approximate 95% confidence interval of 210,000 – 340,000). This estimate includes 

shelf waters to the west of Shetland and Orkney (Hammond et al., 2002). The highest 

densities were observed north of 56ºN, mostly in a north-south band between 1ºE and 3 o E 

(SMRU, 2001). Numbers of porpoises present in UK waters vary seasonally, however, and 

more animals are likely to pass through UK waters than are present at any one time (Jackson 

& McLeod, 2002). 

Harbour porpoises are generally described as a coastal species that frequents relatively 

shallow bays, estuaries and tidal channels, generally in depths less than 200 m in continental 

shelf waters (Klinowska, 1991). However, they have been observed in the deep waters of the 

Norwegian Rinne, in deep water areas between Iceland and the Faroe Islands, and on the 

Rockall and Faroe Banks (Northridge et al., 1995). Summer surveys in the North Sea and 

adjacent waters found porpoises in large numbers offshore as well as in coastal waters 

(Hammond et al., 2002). Porpoises have also been sighted in offshore waters with depths 

between 953 m and 1,502 m off north-west Scotland (Atlantic Frontier) (MacLeod et al., 

2003). By-catch data from Ireland also suggest that porpoises occur regularly offshore, with 

records from up to 220 km from land (Rogan & Berrow, 1996). 

Aggregations of harbour porpoises are often associated at local sites with strong tidal 

features, such as headlands, areas with upwellings, tidal races and rips, or close to reefs and 

small islands, where prey are probably concentrated into patches (Pierpoint, 2001; Read & 

Westgate, 1997). There may be offshore areas supporting similar concentrations that attract 

harbour porpoises, but there is very little data to confirm this. JNCC and the country agencies 

are currently analysing distribution data for harbour porpoises in UK waters to determine 

whether any suitable sites for SAC designation can be found. 

4.4 OFFSHORE BIOLOGICAL ENVIRONMENT 

4.4.1 Plankton 

The planktonic community is composed of a range of microscopic plants (phytoplankton) and 

animals (zooplankton) that drift with the oceanic currents. These organisms form the basis of 

marine ecosystem food chains and many species of larger animals such as fish, birds and 

cetaceans, are dependent upon them. The distribution of plankton, therefore, directly 

influences the movement and distribution of other marine species. The distribution and 

abundance of plankton is heavily influenced by water depth, tidal mixing and thermal 

stratification within the water column. 

The majority of the plankton occurs in the photic zone (the upper 20 m of the sea which 

receives enough light for photosynthesis to occur) (SAHFOS, 2001). The majority of 

phytoplankton are unicellular, and include diatoms and dinoflagellates, whereas zooplankton 

comprise a wide variety of multicellular herbivorous and carnivorous organisms. Typical 

zooplankton organisms are the copepods, arrow worms, krill, jellyfish and sea-gooseberries. 

Zooplankton also includes the larval stages of non-planktonic organisms such as fish, crabs 

and barnacles (SAHFOS, 2001). The composition of the plankton community reflects 

environmental conditions such as salinity, temperature, water movements in the area and the 

presence of local benthic communities that have planktonic larval stages. 

The planktonic community may be vulnerable to elevated concentrations of chemicals or 

hydrocarbons in seawater as a result of planed or accidential releases. However, it is 

generally considered to be less vulnerable to one-off incidents than benthic communities, as 

many species have the capacity to recover quickly due to the continual exchange of 



individuals with surrounding waters (NSTF, 1993). Changes in the distribution and 

abundance of planktonic communities could, however, result in secondary effects on 

organisms that depend on the plankton as a food source, including commercial fish species 

and marine mammals. It is also possible that pollutants ingested by plankton could be 

accumulated by them and bio-accumulate in higher trophic levels (SAHFOS, 2001). 

Phytoplankton 

The phytoplankton community in the northern-central North Sea is dominated by the 

dinoflagellate genera Ceratia (SAHFOS, 2001). Plankton in the North Atlantic and North Sea 

has been monitored using the Continuous Plankton Recorder (CPR) over the last 70 years, 

and the results of this programme have shown an increase in the dinoflagellates, with a 

gradual decrease in the diatom species (DTI, 2001; SAHFOS, 2001). 

Phytoplankton abundance and productivity is dependent on light intensity and nutrient 

availability, which is affected by water column stratification. Densities of phytoplankton 

therefore fluctuate during the year (SAHFOS, 2001). Around the UK in spring a ‘bloom’ of 

phytoplankton is triggered by an increase in sunlight, an increase in the availability of 

nutrients circulated from the deeper waters, and warming of the surface waters (Heath et al., 

1999). Large diatoms such as Thalassiosira spp. and Chaetoceros spp. are usually dominant 

in the spring bloom. This spring bloom is followed by an increase in the abundance of 

zooplankton. After the spring bloom, phytoplankton densities decline through the summer 

(because the establishment of a thermocline reduces the available nutrients), before they 

increase slightly at the end of summer. This secondary, smaller bloom during the autumn 

(September to October) primarily consists of the smaller dinoflagellate species Ceratium. 

Essentially, these spring and autumn ‘blooms’ are normal events, but under certain conditions 

blooms can occur at other times of year, and these often consist of a monoculture. The 

concentrations of organisms in these ‘blooms’ can be very high (Reid et al., 1990), and may 

involve nuisance or noxious species. These ‘Harmful Algal Blooms’ (HAB) can have 

detrimental effects, such as deoxygenation, foam formation, fish mortality, marine mammal 

mortality and a change to the ecosystem. HABs can also result in paralytic, amnesic and 

diarrhetic shellfish poisoning in humans (SAHFOS, 2001). HABs occur frequently in the North 

Sea and are primarily caused by mono-specific blooms, often involving dinoflagellate species. 

Anthropogenic impacts can influence the frequency and extent of HABs, especially through 

the addition of carbon / nitrogen compounds; the addition of oil, in conjunction with high 

nutrient concentrations, can result in mono-specific blooms (SAHFOS, 2001). 

Phytoplankton are widely distributed in the North Sea so the effects of any offshore project is 

likely to be extremely small in comparison with natural variations. 

Zooplankton 

Zooplankton consists of a variety of taxonomic groups, with a diverse range of both 

herbivorous and carnivorous organisms ranging in size from microscopic larval life stages of 

fish and copepods such as Calanus finmarchicus to large jellyfish. The total biomass of 

zooplankton follows a seasonal pattern governed by the availability of phytoplankton, their 

main source of food, and consequently the peak in zooplankton biomass occurs after the 

phytoplankton peak. Zooplankton are not restricted to the upper layers of the water column 

but do exhibit a diurnal movement; generally, they migrate into the upper layers of the water 

column at night to feed, and then descend again to deeper water, for safety, during daylight 

hours (SAHFOS, 2001). 

The zooplankton communities of the northern and southern North Sea are broadly similar and 

the most abundant group is the copepods, which are dominated by Calanus (SAHFOS, 

2001). The larger zooplankton (or megaplankton) includes the euphausiids (krill), thaliacea 

(salps and doloids), siphonophores and medusae (jellyfish). Blooms of salps and doloids 

produce large swarms in late summer to October, depleting food sources for other 

herbivorous plankton with subsequent effects to the higher trophic levels. Siphonophores 

(colonial hydrozoa) can also reach large densities in the North Sea. 

Krill is very abundant throughout the North Sea and is a primary food source for fish and 

whales. Meroplankton is the larval stages of benthic organisms that spend a short period of 



their lifecycle in the pelagic stage before settling on the benthos. Important groups within this 

category include the larvae of starfish and sea urchins (echinoderms), crabs and lobsters 

(decapods), and some fish (DTI, 2001). 

Zooplankton in the area of the proposed development comprises mostly neritic (coastal) 

species and intermediate (mixed water) species, with biomass peaking from early May to mid- 

July until October. The euphasusiid species, Thysanoessa inermis and T. raschi dominate 

during the spring and summer months. During late summer and autumn, there is an 

introduction of oceanic species (such as Calanus finmarchicus and Metridia lucens) via an 

inflow of Atlantic waters. 

Zooplankton communities can be affected by oil, both directly through the hydrocarbon 

content of their food and indirectly via a change in the ecosystem. Reduced egg production 

and an increase in juvenile mortality have been associated with oil contamination, and there is 

a strong suggestion that oil treated with dispersant has a more pronounced effect. Any 

possible long-term genetic changes caused by the disruption of internal chemical signals are 

difficult to recognise and likely to be subtle (SAHFOS, 2001). 

4.4.2 Benthos 

Benthic fauna comprises species which live either within the seabed sediment (infauna) or on 

its surface (epifauna). Such species, which may be either sedentary or motile, and may 

encompass a variety of feeding habits (i.e. filter-feeding, predatory or deposit-feeding), 

occupy a variety of different niches. Bacteria and benthic organisms play a major role in the 

decomposition of organic material that originates from primary production by phytoplankton in 

surface waters and settles on the seabed (NSTF, 1993). Some bacteria can degrade 

hydrocarbons and use it as a source of food source (Clark, 1996). 

Benthic fauna are also typically divided into various categories, principally according to size. 

The largest are the megafauna and this comprises animals, usually living on the seabed, 

which are large enough to be seen in bottom photographs and caught by trawl (i.e. brittle 

stars, sea urchins, sea cucumbers, sea spiders, sponges, corals). Macrofauna are defined as 

those animals that are between 250 µm and 300 µm in size. Meiofauna comprises the 

smaller interstitial animals (mainly nematode worms and harpacticoid copepods) with a lower 

size limit of between 45 µm and 62 µm. 

Colonisation of sediments by different species is largely dependent on the type of sediment 

present and its characteristics. Both physical and biological factors are important in 

determining species abundance and distribution, including seabed depth, water movements, 

salinity, temperature and available oxygen. Infaunal species are particularly vulnerable to 

external influences, which alter the physical, chemical or biological community of the 

sediment. Such infaunal organisms are largely sedentary and are thus unable to avoid 

unfavourable conditions. Each species has its own response and degree of adaptability to 

changes in the physical and chemical environment. Consequently the species composition 

and relative abundance in a particular location provides a reflection of the immediate 

environment, both current and historical (Clark, 1996). 

Benthic fauna are susceptible to physical disturbance of the seabed, for example from fishingtrawls, 

anchoring, pipeline trenching and rock dumping operations, or smothering from 

discharged cuttings (DTI, 2001). The effects of discharged cuttings on benthic fauna include 

physical smothering, the presence of potential toxins (heavy metals and hydrocarbons), and 

organic enrichment (BMT Cordah, 1998). The responses shown by benthic communities to 

cuttings discharges are the result of a combination of these effects. Directly below a 

development, beneath the cuttings pile, the impact is through smothering. Beyond this point, 

the effects of toxins and organic enrichment become more evident, and the changes in the 

species composition, diversity and abundance of benthic communities may be attributed to 

one or all of these impacts (BMT Cordah, 1998). 

In addition to the possible impact from drilling operations, accidental events such as major oil 

spills and blow-outs can result in oil reaching the seabed offshore. Effects reported from such 

accidents range from none detected (e.g. after the Ekofisk blowout in 1977) to chemical 

contamination but no acute biological effects detectable (e.g. after the wreck of the Braer in 

1993) (DTI, 2001). 



During 1986, the whole of the North Sea was surveyed using standard techniques and 

equipment (Künitzer et al., 1992). This survey identified and classified different species 

distributions and assemblages of benthic fauna in relation to factors such as latitude, 

temperature, water depth and sediment type. Based on the findings of this survey, the 

benthic communities in the proposed Bardolino development area would be expected to be 

characteristic of the deep-water infaunal assemblage, which typically has high densities 

(2,863±1,844 individuals per m 2 ) and species richness (51±13 species) (Künitzer et al., 1992). 

Indicator species of this benthic infaunal assemblage include the Thyasira sp. bivalve 

complex and the polychaetes Minuspio cirrifera, Aricidea catherinae and Exogone verugera 

(Künitzer et al., 1992). Epifauna species identified in the area include the starfish Astropecten 

irregularis and Asterias rubens, the echinoid Echinocardium flavescens, the gastropods 

Neptunea antique, Colus gracilis and Scaphander lignarius, tunicates and sponges (Basford 

et al., 1989). 

Benthic faunal analysis was undertaken as part of the Nelson field seabed survey undertaken 

in 2005 and 2006 (Section 4.2.6). A total of 204 species was identified from the 12,055 

individuals recovered from a total of 18 samples. The seabed area more than 500 m from the 

Nelson platform was found to be dominated by the polychaetes Paramphiome jeffreysii, 

Myriochele sp. A., Exogone hebes and the brittle star Ophiura affinis (Hartley Anderson, 

2007). Within 500 m of the Nelson platform the dominant species were the polychaetes 

Chaetozone setosa and Paramphiome jeffreysii (Hartley Anderson, 2007). 

Paramphiome jeffreysii, present in high numbers at all stations sampled, is an opportunistic 

colonising polychaete, characteristic of deep, offshore, cohesive sandy mud. This polychaete 

is common throughout the North Sea in similar habitats and is frequently recorded in the 

vicinity of offshore platforms. 

Thyasira sp and Chaetozone setosa were present in large numbers at Station Nel-01, 200 m 

from the platform. These species are known to be indicative of elevated hydrocarbon 

concentrations in offshore sediments. C. setosa, in particular, is well adapted to colonise and 

exploit disturbed and organically enriched habitats. It is a secondary coloniser, able to move 

into areas once conditions are favourable enough for it to out-compete the primary colonisers 

such as Raricirrus beryli and Capitella capitata (ERT, 2000). Raricirrus beryli was not present 

at any of the stations sampled in the 2007 Nelson survey and Capitella capitata was only 

present at station Nel-01 in very small numbers (7 indiviuals identified in 3 samples). This 

indicates that the sediment in the immediate vicinity of the Nelson platform (200 m) is now 

recovering from previous hydrocarbon pollution. Table 4.11 lists the ten dominant species 

identified at each of the six sample stations. 



Table 4.11 : Dominant species identified at the 2006 Nelson sample stations. Average 

number of individuals from 3 samples. 

Species Nel-01 Species Nel-04 

Myriochele sp. A 12 Grania sp. 25 

Philine scabra 13 Echinocyamus pusillus 28 

Ophelina modesta 13 Exogone verugera 31 

Thyasira indet. 14 Owenia fusiformis 32 

Owenia fusiformis 19 Myriochele sp. A 34 

Nemertea indet. 27 Ophiura affinis 36 

Echinocardium juv. indet. 35 Exogone hebes 39 

Pholoe sp. A 41 Cephalothricidae indet. 47 

Paramphiome jeffreysii 87 Paramphiome jeffreysii 71 

Chaetozone setosa 121 Echinocardium juv. indet. 144 


Echinocyamus pusillus 12 Echinocyamus pusillus 14 

Ophelina modesta 14 Exogone verugera 17 

Owenia fusiformis 20 Owenia fusiformis 17 

Exogone verugera 21 Spiophanes kroyeri 20 

Cephalothricidae indet. 23 Pholoe sp. A 20 

Pholoe sp. A 25 Ophiura affinis 30 

Myriochele sp. A 25 Myriochele sp. A 35 

Ophiura affinis 36 Cephalothricidae indet. 38 

Paramphiome jeffreysii 122 Paramphiome jeffreysii 120 

Echinocardium juv. indet. 137 Echinocardium juv. indet. 140 


Philine scabra 13 Owenia fusiformis 16 

Minuspio cirrifera 15 Philine scabra 16 

Echinocyamus pusillus 20 Exogone hebes 19 

Exogone verugera 25 Myriochele sp. A 21 

Cephalothricidae indet. 36 Pholoe sp. A 24 

Owenia fusiformis 40 Echinocyamus pusillus 27 

Myriochele sp. A 42 Ophiura affinis 38 

Ophiura affinis 59 Cephalothricidae indet. 48 

Paramphiome jeffreysii 108 Echinocardium juv. indet. 70 

Echinocardium juv. indet. 221 Paramphiome jeffreysii 99 

Source: Hartley Anderson (2007) 

Seabed surveys undertaken in Blocks 22/14 for Shell (1990), 22/25 for BP (2000) and 22/29 

for Shell (1997) (UKBenthos, 2000) provide an indication of the benthic fauna expected at the 

proposed Bardolino development area. Benthic fauna retrieved from the sample sites were 

observed to be homogenous throughout the area and typical of fauna found in undisturbed 

sediments of the central North Sea. Macrofauna was dominated by the tube-dwelling 

polychaete Myriochele oculata which is a common member of central North Sea sandy 

associations. Other species commonly found during the environmental surveys were the 

polychaetes Paramphinome jeffreysii and Capitella capitata and juvenile echinoderms 

(Amphiura filiformis) (UKBenthos, 2000). All species present in the sediments studied during 

the above mentioned surveys are comparable with those found in survey undertaken at 

Nelson in 2005 and 2006 (Section 4.2.5). The locations of the sampling sites for the 2005 

and 2006 survey at Nelson, the Shell survey in block 22/29 and the BP survey in block 22/25 

are shown in Figure 4.7. 



Figure 4.7 : Location of seabed surveys undertaken in the central North sea the vicinity of the Bardolino development location (samples sites 

indicated by black circles within marked survey areas) 



Epibenthic trawl studies of the central North Sea have shown that the shrimp Crangon 

allmanni and the hermit crab Anapagurus laevis are typical of the larger and more widely 

dispersed animals found living on the seabed. In addition to the sand-dwelling Ophiura 

ophiura, the hermit crab Pagarus bernhardus, and the starfish Asterias rubens and 

Liocarcinus holsatus, are also present (Jennings et al., 1999). 

The seabed fauna of the North Sea varies mainly according to sediment type and water 

temperature range. The fauna is diverse, but most of the northern/central North Sea area 

does not appear to contain any species of particular conservation concern (DTI, 2001). 

4.4.3 Fish 

Adult and juvenile stocks of finfish and shellfish are an important food source for seabirds, 

marine mammals and other fish species. Fish can be separated into pelagic, demersal and 

shellfish species with the following characteristics: 

• Pelagic species occur in shoals swimming in mid-water, typically making extensive 

seasonal movements or migrations between sea areas. Pelagic species include 

herring, mackerel, blue whiting and sprat. 

• Demersal species live on or near the seabed and include cod, haddock, plaice, 

sandeel, sole, and whiting. 

• Shellfish are generally demersal (bottom-dwelling) species, such as shrimps, crabs, 

Nephrops (Norway lobster), mussels and scallops. 

There are several ways in which offshore oil and gas exploration and production could impact 

fish populations including the potential effects of seismic surveys (especially during the 

spawning season), the impact of drill cuttings, and exposure to hydrocarbon and chemical 

discharges (CEFAS, 2001b). 

Fish are most vulnerable to disturbance or pollution during the egg and juvenile stages of their 

life cycles. Fish that lay their eggs on the sediment (e.g. herring and sandeels) or which live 

in intimate contact with sediments (e.g. sandeels and most shellfish) are particularly 

susceptible to smothering by discharged solids. Other ecologically sensitive fish species 

include cod, plaice and haddock because in the North Sea these stocks are considered to be 

outside ‘safe biological limits’ (WWF, 2001). 

'Safe biological limits' are defined by a minimum safe stock size and a maximum exploitation 

rate, where the stock size is measured in terms of 'spawning stock biomass (SSB)' (which 

represents the total weight of spawning fish each year) and the exploitation rate is called the 

'fishing mortality' (which measures the rate at which fish are removed from the stock by 

fishing). If the stock is either below the minimum safe SSB or above the maximum safe 

exploitation rate, the stock is said to be outside safe biological limits (Scottish Executive, 

2005). Several factors have contributed to some fish stocks being outside ‘safe biological 

limits’ and these include a combination of over-fishing, poor recruitment and poor fisheries 

management, with respect to under estimation of fish stocks and related issues (WWF, 2001). 

The industry-commissioned Fisheries Sensitivity Maps in British Waters and SEA2 Technical 

Report on North Sea Fish and Fisheries (Coull et al., 1998 and CEFAS, 2001b) provide data 

illustrating fish spawning and nursery locations (Figures 4.7 and 4.8). 

The proposed Bardolino development site lies within spawning grounds for mackerel (May to 

August), Nephrops (January to December, peak period is between April and June), lemon 

sole (April to September) and Norway pout (January to April) (Figure 4.7). The proposed 

development area also coincides with nursery grounds for haddock, Norway pout, blue 

whiting and Nephrops (Figure 4.8). 

Spawning and nursery grounds are dynamic features of fish life history and are rarely fixed in 

one location from year to year. Although some fish species exhibit the same broad patterns 

of distribution from one year or season to the next, others show a large degree of variability. 

In addition, fish may spawn earlier or later in the season in response to environmental 

change. For sediment spawners, not all suitable sediment areas might be used in every year 

and areas used will depend on the size of the spawning stock. The information provided in 

Figure 4.7 therfore represents the widest known distribution given current knowledge and 



should not be seen as rigid, unchanging descriptions of presence or absence. Spawning 

times represent the generally accepted maximum duration of spawning (Coull et al., 1998). 

After spawning, fish hatch quickly from their eggs and many species remain in the water 

column as larvae, consuming microscopic organisms and gradually developing the body 

shape and behaviour patterns of adults. At this stage of the life cycle, many species occupy 

discrete areas, either in the water column or on the seabed, where opportunities for feeding, 

and for protection from predators are greatest. Juvenile fish can often be found in nursery 

areas together with slightly older individuals, and occasionally adults. The prevailing water 

temperature and availability of food can alter the position of these nursery grounds from year 

to year. As a result of these factors it is difficult precisely to define the limits of nurseries. The 

maps in Figure 4.8 therefore give an indication of the likely positions of juvenile 

concentrations around the UK, rather than a definitive description of the limits of all nursery 

grounds (Coull et al., 1998). Nursery grounds are used throughout the year, potentially 

making it impossible for an operation to avoid being coincident with the presence of juvenile 

fish. Seismic surveys and the placement of structures on the seabed (CEFAS, 2001b) may 

have an impact upon fish spawning grounds, but as yet there is no direct evidence to suggest 

that these activities cause significant disturbance to nursery areas. 

Bardolino development activities are scheduled to occur between March and August 2009 

(Section 3.3.2); these would coincide with the spawning periods of mackerel, Nephrops 

(Norwegian lobster), lemon sole and Norway pout (Table 4.12). Species such as mackerel 

lemon sole and Norway pout typically have pelagic eggs that are released into the water 

column. The eggs and larvae of lemon sole remain planktonic after hatching, until they 

mature and become demersal. Mackerel eggs and larva remain planktonic after maturation. 

Nephrops benthic spawners, laying their eggs on the seabed and therefore may be at more 

risk from smothering and activities that disturb the seabed. 

Table 4.12 Spawning periods of fish which would coincide with the Bardolino 

development [Months in yellow indicate the proposed development schedule] 

Species J F M A M J J A S O N D Nursery 

Mackerel 

Nephrops * * * 

Lemon sole 

Norway pout 

Haddock 

Blue whiting 

spawning period nursery/juveniles 

* Peak spawning period 

Source: Coull et al. (1998) 

Mackerel are fast-swimming pelagic fish that are widespread in North Atlantic shelf waters. 

The North Sea stock of mackerel has been at a very low level for many years due to high 

fishing pressure and poor recruitment (DTI, 2001). North Sea mackerel over-winter 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 North Sea between May and August 

(CEFAS, 2001b). 

Norway lobsters (Nephrops norvegicus) are mud-burrowing animals and are limited in their 

distribution by the extent of suitable sediments, which are sandy mud to very soft mud. They 

do not migrate, and spend their life in the area in which they settle as larvae. Mature females 

carry eggs from September to April or May, although there is a tendency for Nephrops located 

in northerly waters to spawn later in the year. After hatching, the larval stage lasts 6 to 8 

weeks, before settlement to the seabed (CEFAS, 2001b). 

Because they live in burrows and are therefore unable to move away, Nephrops are 

vulnerable to smothering and the disruption of seabed sediments. Although Nephrops may 

be vulnerable to smothering resulting from the drilling and pipeline activities associated with 

the proposed development, these effects would be of relatively short duration and occur over 

very localised areas of the seabed. 



The centre of distribution of lemon sole is in the coastal waters off northern Scotland and the 

Orkney and Shetland Islands, but they are also found off the eastern coast of England and 

throughout the central and northern North Sea. There do not appear to be seasonal 

differences in distribution, and the species as a whole probably does not undertake extensive 

migrations (CEFAS, 2001b). Little is known about the spawning habits of lemon sole and it is 

thought to spawn everywhere it is found (Figure 4.8). Off the Scottish east coast the 

spawning season extends from April to September (CEFAS, 2001b). 

Figure 4.8 Spawning areas for lemon sole, mackerel, Nephrops, and Norway pout in 

the vicinity of the Bardolino development 


Norway pout are generally found in waters 80 m to 200 m deep with sandy and muddy 

substrates, but they also occur in waters up to 450 m deep in the Norwegian Deep. 

Spawning usually takes place between January and April on the continental shelf, with the 

period of most intense activity during February and March. In deeper parts of the northern 

North Sea spawning occurs slightly later, between March and May, and may extend into early 

summer. The precise location of spawning areas is not well understood, but most spawning 

activity appears to be restricted to waters within the depth range of 50 to 200 m (Figure 4.8). 

Norway pout are not generally considered to have specific nursery grounds, but pelagic 0group 

fish remain widely dispersed in the northern North Sea close to spawning grounds 

(CEFAS, 2001b). 



Figure 4.9 Nursery areas for blue whiting, haddock, Nephrops and Norway pout in the 

vicinity of the Bardolino development 


4.4.4 Marine mammals 

Marine mammals include whales, dolphins and porpoises (cetaceans), and seals (pinnipeds). 

They may be vulnerable to the effects of oil and gas activities and can be impacted by noise, 

contaminants, oil spills and any effects on prey availability (SMRU, 2001). The abundance 

and availability of prey, including plankton (Section 4.4.1) and fish (Section 4.4.3), can be of 

prime importance in determining the reproductive success or failure of marine mammals. 

Changes in the availability of principal prey species may be expected to result in population 

level changes of marine mammals but it is currently not possible to predict the extent of any 

such changes (SMRU, 2001). 

Cetaceans 

Most whales and dolphins range widely, and there are no species which are exclusively 

British. About 16 of the 80 known species of cetacean can be seen off the British coast 

(SMRU, 2006). These include large baleen whales such as fin, sei and humpback whales, 

and the largest toothed whale, the sperm whale (SMRU, 2006). Medium-sized whales are 

represented by the pilot and killer whales, while small species include Risso’s, white-sided, 

white-beaked, common and striped dolphins as well as the harbour porpoise and bottlenose 

dolphin (Reid et al., 2003; SMRU, 2006). Cetaceans are widely distributed in UK waters and 

are recorded throughout the year (Reid et al., 2003; Stone 2003a; UKDMAP, 1998). 

Cetacean distribution may be influenced by variable natural factors such as water masses, 

fronts, eddies, upwellings, currents, water temperature, salinity and length of day. A major 



factor likely to influence cetacean distribution is the availability of prey, mainly fish, plankton 

and cephalopods (Stone, 1997). 

Minke whales, white-beaked and white-sided dolphins, and harbour porpoises may occur 

regularly in the northern-central North Sea (Table 4.13). Killer, long-finned, pilot and sperm 

whales, and common, striped, Risso’s and bottlenose dolphins, are less frequently sighted in 

the northern-central North Sea. Other species, including northern bottlenose, Sowerby’s 

beaked, and fin and humpback whales, are encountered very infrequently (Hammond et al., 

2002; Northridge et al., 1995; Reid et al., 2003; SMRU, 2001; Stone 1997, 1998, 2000, 2001, 

2003a and b; UKDMAP, 1998). 

Table 4.13 Sightings of cetaceans within Quadrant 22 and surrounding quadrants 

[Months in yellow indicate the proposed development schedule] 

Species J F M A M J J A S O N D 

Harbour porpoise 

White-beaked dolphin 

Minke whale 

White-sided dolphin 

Killer whale 

Common dolphin 

Source: UKDMAP (1998) 

Present within Quadrant 22 Present in surrounding Quadrants 

The harbour porpoise is the commonest cetacean in the North Sea (see Section 4.3.2). 

Highest densities in summer are found north of 56ºN, mostly in a north-south band between 

1ºE and 3°E. During the SCANS survey in the summer of 1994 there were an estimated 

268,000 porpoises in the North Sea. The northern and central areas of the North Sea appear 

to be important areas for harbour porpoises, especially in summer (SMRU, 2001). 

White-beaked dolphins are distributed over the continental shelf, and in the North Sea they 

tend to be more numerous within about 200 nm of the Scottish and north-eastern English 

coasts (Northridge et al., 1995). The abundance of white-beaked dolphins in the North Sea 

areas during the SCANS survey in the summer of 1994 was 7,856 (95% confidence interval 

4,000–13,300). This estimate includes shelf waters to the west of Shetland and Orkney 

(Hammond et al., 2002). White-beaked dolphins are present throughout the year in the North 

Sea, with most sightings recorded between June and October (Reid et al., 2003). 

Minke whales occur throughout the central and northern North Sea, particularly during the 

summer months (SMRU, 2001). There is no direct evidence that minke whales in the 

Northern Hemisphere migrate, but in some areas there appear to be shifts in latitudinal 

abundance with season (SMRU, 2001). This is true for the North Sea, where minke whales 

appear to move into the North Sea at the beginning of May and are present throughout the 

summer until October (Northridge et al., 1995). The estimated summer abundance of minke 

whales in North Sea areas during the SCANS 1994 survey was 7,200 (approximate 95% 

confidence interval 4,700 – 11,000). This estimate includes shelf waters to the west of 

Shetland and Orkney (Hammond et al., 2002). During the SCANS survey, the highest 

densities were recorded in the northwest North Sea, particularly off the mainland coast of 

Scotland (SMRU, 2001). It is apparent that the central and northern SEA-2 areas are 

important for minke whales in summer (SMRU, 2001). 

Killer whales have been observed throughout the northern North Sea in most months (SMRU, 

2001; Reid et al., 2003). Between Shetland and Norway, the species has been regularly 

recorded from November to March (Reid et al., 2003). Seasonal movements may be 

associated with particular prey, including seals and herring (Reid et al. 2003). An association 

of killer whales with oil platforms has been reported (SMRU, 2001). 

The Atlantic white-sided dolphin is primarily an offshore species but has been recorded during 

a number of surveys in the North Sea, especially during summer (Northridge et al., 1997; 

Reid et al., 2003). It shares most of its range with the white-beaked dolphin, but in the 

eastern North Atlantic it has a mainly offshore distribution and is consequently rarer than 

white-beaked dolphin over shelf waters (SMRU, 2001). Its presence in the North Sea is 



seasonal, with the majority of sightings recorded between May and September (SMRU, 

2001). 

In the North Sea, bottlenose dolphins are occasionally sighted outside coastal waters. 

Individuals from the resident population in the Moray Firth are known to range widely along 

the east coast of Scotland (Wilson et al., 2004) and they may also move off-shore during the 

winter (SMRU, 2001; see Section 4.3.2). 

Sightings of Risso’s dolphins in the northern North Sea are mainly between July and August, 

although some animals are present off north-east Scotland and Shetland in winter (Reid et al. 

2003). Common dolphins are occasionally sighted in the North Sea, also mainly in summer 

(June to September) (Reid et al., 2003). Common dolphins are generally found in oceanic 

and shelf-edge waters, but do occasionally use coastal waters. Striped dolphins are generally 

rare in UK waters, although they have been observed in the North Sea (Reid et al., 2003; 

Stone, 2001). 

Most records of pilot whales around the UK are from waters greater than 200 m deep, with 

relatively few occurrences in the shallower waters of the North Sea. Incidental sightings of 

pilot whales in the North Sea do, however, appear to be more numerous between November 

and January (Reid et al., 2003). 

Sperm whales are normally distributed to the west and north of the UK on, and beyond, the 

continental shelf break. They have also been recorded fairly regularly in waters around the 

Orkney Islands and the Shetland Islands, with sightings and strandings reported in most 

months (SMRU, 2001). Several sightings and strandings have been recorded from the North 

Sea in the last decade. Males migrate to high latitudes to feed and, as a result, all sperm 

whales sighted or stranded in the North Sea to date have been males (SMRU, 2001). 

All cetacean species are listed in Annex IV of the EC Habitats Directive, which protects them 

from any deliberate disturbance, particularly during the periods of breeding and migration. 

Pinnipeds (seals) 

Harbour seals (Phoca vitulina) are one of the most widespread pinniped species and are 

found in all coastal waters around the North Sea. A minimum population estimate in the 

North Sea is 38,000 and this represents just over half the estimated population of the 

Northeast Atlantic subspecies (SMRU, 2001). 

Grey seals (Halichoerus grypus) are restricted to the North Atlantic and the total population is 

approximately 300,000 animals. The population in the northeast Atlantic has been increasing 

at around 6 % annually since the 1960’s; its current size is estimated at around 130,000- 

140,000 individuals, of which approximately 70,000 are associated with breeding colonies in 

the North Sea (SMRU, 2001). 

Grey and harbour seals are resident in UK waters and occur regularly over large parts of the 

North Sea (Stone, 2001; SMRU, 2001). Both species breed in the UK, with common seals 

pupping in June / July and grey seals pupping between September and December. British 

populations of grey and common seals represent approximately 40% and 5%, respectively, of 

the world populations of these species (SMRU, 2001). 

Both species are found along the UK coastline but there are few data available on the 

distribution and abundance of seals when offshore (see Section 4.3.2). Tracking of seals 

suggests they make feeding trips lasting 2 to 3 days, travelling less than 40 km from their 

haul-out sites, and with the animal ultimately returning to the same haul-out site from which it 

departed (JNCC, 2002). Grey seals may spend more time further offshore than common 

seals. The Bardolino development is over 185 km from the UK coastline; so it is unlikely that 

grey and common seals would be found regularly in the vicinity of the proposed development. 

Grey and harbour seals are listed in Annex II of the Habitats Directive (Section 4.3.2). 

4.4.5 Seabirds 

Seabirds are not normally affected by offshore oil and gas operations (DTI, 2001). Birds are 

vulnerable to oiling from surface oil pollution, which can cause direct toxicity through 

ingestion, and hypothermia as a result of the birds’ inability to waterproof their feathers. 



During the moulting season, certain species (e.g. guillemot, razorbill and puffin) which 

become flightless and spend a large amount of time on the water surface, are particularly 

vulnerable to surface oil pollution (DTI, 2001). To assess the relative risk for different 

species, the Joint Nature Conservation Committee (JNCC) Seabirds at Sea Team (SAST) 

has developed an index to assess the vulnerability of bird species to the threat of oil pollution. 

This offshore vulnerability index (OVI) is derived by taking account of the following four factors 

(Williams et al., 1994): 

• the amount of time spent on the water; 

• total biogeographic population; 

• reliance on the marine environment; and 

• potential rate of recovery. 

The seasonal vulnerability of the seabirds in the proposed development area (UKCS Blocks 

22/11, 22/12, 22/13 and surrounding blocks) is derived from the JNCC block-specific 

vulnerability data (JNCC, 1999; UKDMAP 1998; Table 4.14). Seabird vulnerability to surface 

pollution varies throughout the year with peaks in late summer after breeding when the birds 

disperse into the North Sea, and during the winter months with the arrival of over-wintering 

birds. 

The most sensitive times of year in the proposed Bardolino development area (Blocks 22/11, 

22/12 and 22/13) and surrounding areas is July to November when vulnerability to oil pollution 

is “high”. Vulnerability ranges from “moderate” to “low” for the remainder of the year. The 

overall seabird vulnerability to surface pollution in the proposed development area is 

“moderate” (Table 4.14). Bardolino development activities are scheduled to occur between 

April and August (Section 3.3.2), which will coincide with the period of high vulnerability for 

seabirds. 

Table 4.14 Monthly vulnerability of seabirds in the area of the proposed Bardolino 

development [Months in yellow indicate the proposed drilling schedule] 

Block J F M A M J J A S O N D All 

22/6 3 3 4 4 4 4 2 3 1 2 1 3 

22/7 3 3 4 4 4 4 2 3 1 2 1 3 

22/8 3 3 4 4 4 4 2 2 1 2 1 3 

22/9 3 4 4 4 4 3 2 2 2 1 3 

22/11 3 3 4 4 4 2 3 1 2 2 3 

22/12 3 3 4 4 4 2 3 1 2 2 3 

22/13 3 3 4 4 4 2 3 1 2 2 3 

22/14 3 4 4 4 3 3 2 2 3 4 

22/16 3 3 4 4 4 2 3 1 2 2 3 3 

22/17 3 3 4 4 4 2 3 1 2 2 3 3 

22/18 3 3 4 4 4 2 3 1 2 2 3 3 

22/19 3 3 4 4 4 3 3 2 2 2 3 4 

KEY 1 Highest Seabird Vulnerability 

2 

3 

High 

Moderate 

Source: JNCC (1999) 

4 Lowest Seabird Vulnerability 

No data available 

Internationally important numbers of several species of seabird breed on the North Sea 

coastal margin, and depend on the offshore North Sea for their food supply and, for much of 

the year, their habitat. Seabird species which breed regularly around mainland North Sea 

coasts include the fulmar, cormorant, shag, gannet, six species of gull and five species of tern 

(DTI, 2001). 



The most important factor currently affecting seabird numbers is probably the quality and 

abundance of prey. Pollution of the sea by oil, predominantly from merchant shipping, can be 

a major cause of localised seabird mortality. Although locally important numbers of birds 

have been killed directly by oil spills, such spills have primarily been associated with the 

transportation of oil, and little or no direct mortality of seabirds has been attributed to 

exploration and production activities. 

In general, offshore areas of the North Sea contain peak numbers of seabirds following the 

breeding season and through winter, with birds tending to forage closer to coastal breeding 

colonies in spring and early summer (DTI, 2001). 

Of the species commonly present offshore in the North Sea, gannet, skuas and auk species 

(guillemot, razorbill and puffin) may be considered to be most vulnerable to oil pollution due to 

a combination of heavy reliance on the marine environment, low breeding output with a long 

period of immaturity before breeding, and the regional presence of a large percentage of the 

biogeographic population. 

Species commonly found in the offshore waters, including the proposed development area, 

are the fulmar, gannet, guillemot, razorbill, and kittiwake, and herring, great black-backed and 

lesser black-backed gulls (DTI, 2001). Other species which are recorded at lower levels 

include the pomarine skua, Arctic skua, black-headed gull, common gull, common tern, Arctic 

tern, black tern, little auk and puffin. 

4.5 SOCIO-ECONOMIC ENVIRONMENT 

4.5.1 Commercial fishing industry 

An assessment of the fishing industry in the proposed development area has been derived 

from International Council for the Exploration of the Seas (ICES) fisheries statistics, provided 

by the Scottish Executive Environment and Rural Affairs Department (SEERAD). Oil and gas 

exploration and production operations have the potential to interfere with fishing activities, for 

example as a result of the exclusion of fishing vessels from around subsea wellheads, the 

area adjacent to platforms, and associated structures which require protection (CEFAS, 

2001b). It is therefore important to have an understanding of the fishing intensity in the 

development area in order to evaluate the potential impacts associated with the proposed 

activities on the fishing industry. 

For management purposes, ICES collates fisheries information for individual rectangles 

measuring 30nm by 30nm. Data have been obtained for ICES rectangles 44F1 and 43F1, 

which coincide with the proposed development area. Statistical data from the ICES 

rectangles provides information on the UK fishing effort and live weight of demersal, pelagic 

and shellfish caught by all UK vessels between 2002 and 2006 (SEERAD, 2006a and 2008a). 

Data on the economic value of the fishing industry in this area have been produced based on 

UK catches and landings (SEERAD, 2008b). 

The overall value of the different species by area (financial yield per ICES square) is an 

indication of the differential worth of areas and is used as a method of expressing commercial 

sensitivity (Coull et al., 1998). 

The type of fishing gear and techniques employed by fishermen depends on a variety of 

factors, such as: 

• species fished, whether these are demersal, pelagic or shellfish; 

• depth of water and seabed topography; and 

• seabed characteristics. 

Species found in the water column (pelagic species) are fished using techniques that do not 

interact with the seabed, whereas demersal and shellfish species are generally fished on or 

near the seabed and there is therefore the potential for these gears to interact with structures 

placed on the seabed. 



Fishing effort 

Fishing effort in ICES rectangles 44F1 and 43F1 has decreased from 593 days in 2002 to 283 

days in 2006 (Table 4.15). Demersal fishing, such as bottom pair trawling and otter trawling, 

dominated the fishing effort in ICES rectangles 44F1 and 43F1 between 2002 and 2006. 

Both finfish, such as cod, whiting, haddock and flatfish, and shellfish species, such as 

Nephrops which are found on or near the bottom, are taken by demersal fishing methods. 

Table 4.15 UK fishing effort (sum of days fished) using different gear types in ICES 

rectangles 44F1 and 43F1 (combined) in the period 2002 to 2006 

Fishing gear 2002 2003 2004 2005 2006 

Beam trawls 1 0 0 0 0 

Longlines (not specified) 0 0 0 4 0 

Nephrops trawls 47 23 10 8 0 

Otter trawls - bottom 269 348 214 141 132 

Otter trawls - midwater 2 0 3 4 9 

Otter trawls – not specified 0 0 0 14 25 

Otter twin trawls 25 16 21 14 21 

Pair seines 30 0 0 1 0 

Pair trawls - bottom 124 48 0 57 82 

Pair trawls - midwater 21 0 9 3 2 

Scottish seines 73 30 15 34 13 

Total 593 466 271 289 283 

Source: SEERAD (2006a and 2008a) 

The relative fishing effort in the Bardolino development area (ICES rectangles 44F1 and 

43F1) in 2006 was “very low” in comparison to other areas of the North Sea. The relative 

fishing effort for demersal, Nephrops and shrimp fisheries was “very low” to “low”, with no 

recorded fishing effort for shellfish fisheries (Table 4.16; SEERAD, 2008b) 

Table 4.16 The annual relative fishing effort (days fished by all UK vessels over 10nm) 

in the development area during 2006, compared to other areas of the North Sea 

Fisheries 

ICES Rectangle 

44F1 43F1 

Demersal 71.31 to 205.88 days 0 to 71.31 days 

Pelagic 9.08 to 32.01 days 0 to 9.08 days 

Nephrops & Shrimp 0 to 261.20 days 0 to 261.20 days 

Shellfish (excluding Nephrops and Shrimp) None None 

All 0 to 249.49 days 0 to 249.49 days 

Key: 


Very High High Moderate Low Very Low None 

Fishing activity occurs throughout the year in the proposed development area (Figure 4.10). 

Between 2002 and 2006 the monthly fishing effort for ICES rectangles 44F1 and 43F1 

(combined) ranged from 2 days in December 2004 to 143 days in September 2002. In each 

year there was fishing activity in the proposed development area in every month (Figure 

4.10). 



Figure 4.10 Monthly UK fishing effort (sum of days fished) in ICES rectangles 44F1 and 

43F1 (combined) between 2002 and 2006 

Fishing effort (sum of days fished) 

200 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 



Catch composition 

Between 2002 and 2006 the annual total live weight of fish landed from the two ICES 

rectangles that coincide with the proposed development, ranged from 374 tonnes in 2003 to 

1,601 tonnes in 2006 (Table 4.17). 

Demersal species accounted for the majority of the fish species landed, accounting for 49%, 

71% and 41% of the live weight landed in 2002, 2003 and 2004, respectively. However, in 

2005 and 2006 pelagic species dominated the fish species landed, accounting for 52% and 

67% respectively (Table 4.17). 

Table 4.17 Total landings (tonnes) of demersal, pelagic, crustacean and mollusc 

species caught in ICES rectangles 44F1 and 43F1 (combined), by the UK vessels 

between 2002 and 2006. 

Total landings (tonnes) 

Species Type 2002 2003 2004 2005 2006 

Shellfish 88 109 102 83 82 

Demersal 441 265 192 379 450 

Pelagic 372 0 172 496 1,069 

Total 901 374 466 958 1,601 


In 2006, herring, haddock and Nephrops accounted for approximately 87% of the fish species 

landed from ICES rectangles 44F1 and 43F1. Other species landed included lemon sole 

(4%), mackerel (4%) and whiting (2%) (Figure 4.11). 


2002 

2003 

2004 

Total


Figure 4.11 Main species landed from ICES rectangles 44F1 and 43F1 (combined) in 

2006 (%live weight) 

Herring 

62% 

Source: SEERAD (2008b) 

Value 

Lemon Sole 4% 

Mackerel 4% 

Nephrops 5% 

Haddock 

19% 

Monks or Anglers 

1% 

Whiting 2% Witch 

Page 4-34 April 2008 

Plaice 

1% 

1% 

Cod 

1% 

Cod 

Haddock 

Hake 

Halibut 

Herring 

Lemon Sole 

Ling 

Mackerel 

Monks or Anglers 

Nephrops (Norway Lobster) 

Plaice 

Saithe 

Squid 

Whiting 

Witch 

The total value of fish landed ranged from about £0.5 million in 2004 to about £1.2 million in 

2006, and was predominantly demersal species. The percentage value of demersal species 

ranged from 43% in 2004 to 62% in 2002 and 2005 (Table 4.18). 

Table 4.18 Value (£thousands) of demersal, pelagic, crustacean and mollusc species 

caught between 2002 and 2006 in ICES rectangles 44F1 and 43F1 (combined), by 

the UK vessels. 

Value (£000) 

Species Type 2002 2003 2004 2005 2006 

Shellfish 213.4 258.8 230.9 200.4 277.3 

Demersal 476.1 303.2 199.5 514.8 593.9 

Pelagic 84.6 0.0 29.0 118.2 323.4 

Total 774.1 561.9 459.4 833.4 1,194.6 


SEERAD (2006b) provided the ‘relative value in 2004’ of the demersal, pelagic, Nephrops and 

shrimps, and shellfish (excluding Nephrops and shrimps) fisheries, and for all species landed 

by UK vessels, for the proposed development area (ICES 44F1 and 43F1) compared to all 

areas fished around the UK. The ‘relative value’ gives an indication of sensitivity, where 

damaging events, such as an oil spill, would be of more concern in an area of higher fisheries 

value than a similar spill in less productive waters. 

In the proposed Bardolino development area the ‘relative value’ of the demersal, pelagic, 

Nephrops and shellfish fisheries is “low” (Table 4.19). Overall, taking into account all species, 

the ‘relative value’ for the proposed development area is low (SEERAD, 2006b).


Table 4.19 Relative value of fisheries in the proposed development area 

Relative Value 

ICES Rectangle 

44F1 43F1 

Demersal £385,187 - £1,198,696 £0 - £385,187 

Pelagic £0 - £300,867 £0 - £300,867 

Nephrops & Shrimp £235,258 - £911,795 £0 - £235,258 

Shellfish (excluding Nephrops and Shrimp) £0 - £128,377 £0 - £128,377 

All Species £759,363 - £2,438,838 £0 - £759,363 

Key: 

Source: SEERAD (2008b) 

4.5.2 Shipping 

Very High High Moderate Low Very Low None 

Shipping traffic within the northern North Sea is relatively moderate, with an average of 

between 1 and 10 vessels per day on routes passing through these waters. The majority of 

shipping traffic comprises merchant ships, supply vessels and tankers (BMT Cordah, 2001). 

Shipping routes that pass within a 10 nm radius of the Howe subsea manifold were identified 

using Anatec’s UK shipping route database, ShipRoutes (Anatec UK Ltd., 2006). The 

proposed location of the Bardolino well site and associated pipelines occur within the 10 nm 

radius of the shipping route study. 

The ShipRoutes database is continuously updated and takes into account changes to 

shipping routes necessitated by new and existing oil and gas installations. It should be noted 

that the database does not included details of routes that are termed as non-routine traffic, 

e.g. fishing vessels and traffic to mobile drilling units. 

A total of 12 different shipping routes were identified as passing within 10 nm of the Howe 

subsea manifold with an annual traffic volume of 624 ships per year (Table 4.20) averaging 1 

to 2 vessels per day (Anatec UK Ltd., 2006). 

Table 4.20 Routes passing within 10 nm of the Howe subsea manifold in ascending 

order of Closest Point of Approach (CPA) 

Route 

No. 

Description CPA 

(nm) 

Bearing 

(°) 

Ships Per 

Year 

% of 

Total 

1 Aberdeen (GBR) - Egersund* 0.7 345 20 3% 

2 Aberdeen - Everest ASCo CNS* 2.2 341 108 17% 

3 Amsterdam - Lerwick Direct* 2.4 241 11 2% 

4 Forth - Boknafjorden* 2.4 327 55 9% 

5 Iceland - Hamburg* 2.5 48 30 5% 

6 Tees - Sognefjorden* 3.1 113 100 16% 

7 Alba Field - Rotterdam* 3.3 262 60 10% 

8 Peterhead - PolandE* 3.6 177 85 14% 

9 Fraserburgh - Kattegat* 3.7 355 30 5% 

10 Tay-Boknafjorden* 6.8 331 25 4% 

11 Tees-N Norway / Russia* 9.0 292 50 8% 

12 PolandE - Fraserburgh* 9.2 359 50 8% 

TOTAL 624 100% 

* 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 UK Ltd. (2006) 

Routes 1, 5 and 6 are located close to the Bardolino well site, tie-back pipelines and Howe 

subsea manifold. Details of these routes are as follows: 

• Route No. 1 is used by an estimated 20 vessels per year between Aberdeen (GBR) 

and Egersund. Cargo vessels, approximately 1,500 to 5,000 dwt in weight account 

for all vessels travelling this route. This route passes to the north of the proposed 

locations for the Bardolino well and associated tie-back pipelines. 

• Route No. 5 is used by an estimated 30 vessels per year between Iceland and 

Hamburg. The majority of vessels travelling this route are cargo vessels ranging from 

1,500 to 5,000 dwt to 15,000 to 40,000 dwt in weight. This route passes to the 

northeast of the proposed locations for the Bardolino well and associated tie-back 

pipelines. 

• Route No. 6 is used by an estimated 100 vessels per year between Tees and 

Sognefjorden. Tanker vessels, ranging from 1,500 to 5,000 dwt, 5,000 to 15,000 dwt 

and 15,000 to 40,000 dwt in weight, travel this route. This route passes to the 

southeast of the proposed locations for the Bardolino well and associated tie-back 

pipelines. 

Figure 4.12 illustrates a break down in the type of vessels which use the 12 routes within the 

10 nm radius of the Howe template. Cargo shipping is the most significant vessel traffic, 

accounting for 52 % of vessel movements. 

Figure 4.12 Distribution of vessel type within 10 nm of the Bardolino site 

52% 

Source: Anatec UK Ltd. (2006) 

4.5.3 Oil and gas industry 

30% 


1% 

17% 

Cargo 

Tanker 

Ferry 

Offshore 

The proposed Bardolino development is located in a well developed oil and gas area of the 

central North Sea (Figure 4.12). The Howe subsea development, the Nelson platform and 

the Forties Alpha platform are located approximately, 3 km, 16 km and 27 km to the west 

respectively, while the Everest and Montrose platforms are located approximately 27 km to 

the north-east, and 20 km to the south, respectively (Figure 4.13). 

4.5.4 Communications, wrecks and dredging 

There are no communication cables in the vicinity of the proposed development site (BMT 

Cordah, 2001; UKDMAP, 1998). 

Within the central North Sea SEA2 area there are 524 confirmed and possible wrecks, but 

there are no designated wreck sites located within the vicinity of the proposed development. 

In addition to wrecks and possible wrecks, there are 84 recorded non-wreck items in the 

central North Sea SAE2 area, including lost cargoes, anchors, cables and large boulders 

(BMT Cordah, 2001).


There are no licensed sites for marine aggregation extraction in the vicinity of the proposed 

development area (BMT Cordah, 2001; DTI, 2001; UKDMAP, 1998). 

4.5.5 Military uses 

There are no recorded historic military disposal sites within or close to the proposed 

development area. There are no areas currently used by the Air Force and Navy for military 

exercises in the vicinity of the proposed development site (BMT Cordah, 2001). 

Figure 4.13 Oil and gas fields in the vicinity of the proposed Bardolino development 



Source: BERR (2008) 

4.6 SUMMARY AND SEASONAL ENVIRONMENTAL SENSITIVITIES 

The proposed Bardolino development is located in Blocks 22/11, 22/12 and 22/13 of the 

United Kingdom Continental Shelf (UKCS) in the central North Sea. 

The water depth at the proposed development site is approximately 85 to 91 m and the 

topography of the seabed is generally relatively flat. Sediments in the proposed development 

area comprise a veneer of sand (0.3 m thick) with shell fragments, with occasional to 

numerous exposures of underlying clays. 

Current speeds in the area decrease with increasing water depth; the maximum tidal current 

speed is approximately 1 m/s. The background, or residual, flow in the central North Sea 

(associated with North Sea circulation patterns) is typically 0.2 m/s towards the south. Water 

masses in the central North Sea are generally well mixed, but a thermocline forms during the 

summer months, resulting in a warm surface layer of 20 to 40 m depth forming above the 

cooler bottom layer. 

Wind speed and direction are variable throughout the year but predominantly range from 

moderate to strong breezes, and south-westerly winds predominate. Sea surface 

temperatures in the area of the proposed development can range from 0 ºC to 22 ºC, 

although mean temperatures are generally around 15 ºC in summer and 5 ºC in winter. 

Salinity in the area shows little seasonal variation and is generally around 35 ppt. 

None of the Annex I habitats listed in the Habitats Directive that occur in UK offshore waters 

are present in close proximity to the proposed development site. The Bardolino development 

is located outside the Witch Ground and known areas of gas seep. Currently, the closest 

possible SAC to the area is the Scanner Pockmark, which is approximately 67 km from the 

development area. 

The harbour porpoise is the only Annex II species to be sighted within the close vicinity of the 

proposed development area, with sightings recorded during June and July. Harbour 

porpoises are present throughout most of the North Sea throughout the year, with increased 

numbers occurring between May and October. 

Phytoplankton of the central North Sea predominantly comprises diatoms and Chaetoceros 

species. Production cycles of phytoplankton have a characteristic main peak in spring 

followed by a secondary peak in autumn. Zooplankton of the central North Sea comprises 

mostly neritic (coastal water) and intermediate (mixed water) species. 

Macrofauna of the proposed development area are typical of sandy sediments in the central 

North Sea; infauna are typically dominated by polychaete worms, and epibenthic species 

include the shrimp Crangon allmanni and the hermit crab Anapagurus laevis. 

The proposed Bardolino development lies within spawning grounds for mackerel (May to 

August), lemon sole (April to September), Norway pout (January to April) and Nephrops 

(January to December, peak period is between April and June), and also coincides with 

nursery areas used by haddock, Norway pout, blue whiting and Nephrops. 

Minke whales, white-beaked and white-sided dolphins and harbour porpoises may occur 

regularly in the northern-central North Sea. Killer, long-finned pilot and sperm whales, 

common, striped, Risso’s and bottlenose dolphins are less frequently sighted in the northerncentral 

North Sea, while other species including northern bottlenose, Sowerby’s beaked, fin 

and humpback whales are encountered very infrequently. Cetacean sightings have been 

recorded throughout the year in the proposed development area, although most species are 

more abundant during summer months. 

Seabird vulnerability to surface pollution varies throughout the year with peaks in late summer 

following breeding, when the birds disperse into the North Sea, and during the winter months 

with the arrival of over-wintering birds. The most sensitive times of year in the proposed 

development area are between July and November when vulnerability to oil pollution is high, 

and this coincides with the proposed drilling activities. Vulnerability ranges from moderate to 

low for the remainder of the year. The overall seabird vulnerability to surface pollution in the 

development area is moderate. Species commonly found in the offshore waters, including the 



proposed development area, are fulmar, gannet, guillemot, razorbill, and kittiwake, and 

herring, great black-backed and lesser black-backed gull. 

Other users of the sea in the location include commercial fishing and shipping. The area is 

fished throughout the year, with most activity occurring during June, September and 

November. Demersal, pelagic and crustacean species are caught in the area, with demersal 

species dominating the total value of fish landed. The overall relative value of fishing in the 

area in 2006 is low. 

Shipping traffic comprises 12 routes within 10 nm of the development area, with 

approximately 624 vessels per year (equivalent to 1 to 2 vessels per day). 

In the context of this report, Environmental Sensitivity is defined as the capacity of a habitat or 

organism to respond positively or negatively to the cause of an environmental impact. On the 

basis of this report, it can be concluded that sufficient data are available to enable the 

adequate assessment of the physical, chemical, biological and socio-economic components 

of the environment (i.e. environmental receptors) in the proposed development area and 

identify any environmental sensitivities. 

Table 4.21 provides a summary of the seasonal sensitivity of environmental receptors that 

can be subjected to environmental impacts in the area of the proposed Bardolino 

development. It also identifies the potential causes of impacts (i.e. environmental aspects) 

associated with the development to which these receptors could be vulnerable. 

The environmental risk assessment (Section 5) identifies and assigns significance to impacts 

and risks associated with routine, abnormal and emergency events. The evaluation takes 

account of the activity causing the impact or risk and the sensitivity of the receptor (as 

summarised in Table 4.21). 



Table 4.21 Summary of seasonal environmental sensitivities for the proposed 

Bardolino development area [Months in yellow indicate the proposed development 

schedule] 


Habitats Directive: Annex I Habitats 

There are no known Annex I Habitats in the vicinity of the proposed development area. The site lies outside the gas 

seep are and no pockmarks were identified during surveys at the proposed rig site and pipeline route. 

Currently, the closest possible SAC to the area is the Scanner Pockmark which is approximately 67 km from the 

Bardolino development. 

Habitats Directive: Annex II Species 

The harbour porpoise is the only Annex II species to be sighted within the vicinity of the proposed development area. 

Sightings have been recorded in proposed development area during June and July, although they may be present in 

the area throughout the year. 

Harbour porpoises, as are most marine mammals, are potentially vulnerable to noise, contaminants, oil spills and 

any effects on prey availability associated with the proposed development. The UK currently has no proposed SACs 

for harbour porpoises. 

Plankton 

Plankton is vulnerable to oil and chemical discharges. Planktonic organisms constitute a major food resource for 

many commercial fish species, benthic species and marine mammals, so any changes in their abundance, 

distribution and composition are important. There is also the possible bioaccumulation of pollutants ingested by 

plankton. Plankton is widely distributed over the North Sea and peak plankton productivity generally occurs in spring 

and summer. 

Benthic fauna 

Benthic fauna are vulnerable to disturbance of the seabed sediments which form their habitats, for example during 

the installation of pipelines and subsea structures, anchoring of the rig and vessels, and the discharge of cuttings. 

The effects of discharged cuttings on benthic fauna include physical smothering, the presence of potential toxins 

(heavy metals and hydrocarbons), and organic enrichment. Benthic fauna are an important food resource to 

demersal fish and shellfish. Benthic communities in the development area are similar to those found throughout the 

surrounding area of the central North Sea and no rare species are known to occur in this area. 

Finfish and Shellfish Populations 

Finfish and shellfish are vulnerable to pollution, such as oil and chemical discharges, the impact of drill cuttings, and 

the potential effects of seismic surveys, especially during the egg, larval and juvenile stages of their lifecycle. 

Demersal spawning species and fish/shellfish that live in close association with seabed sediments are particularly 

vulnerable to any sediment disruption, for example during the installation of subsea structures, anchoring of the rig 

and vessels, and discharge of cuttings. 

The proposed development area lies within spawning grounds for mackerel (May to Aug), lemon sole (Apr to Sept), 

Norway pout (Jan to Apr) and Nephrops (Jan to Dec, peak period is between Apr and Jun) and coincides with 

nursery grounds for haddock, Norway pout, blue whiting and Nephrops. Fish species present in the proposed 

development area are generally distributed throughout the North Sea. 




Cetaceans 

Several marine mammal species are present throughout the North Sea throughout the year. Killer and minke 

whales, white-beaked and white-sided dolphins, and harbour porpoises are widely distributed in the northern-central 

North Sea and may occur regularly in the vicinity of the proposed development. Long-finned pilot and sperm whales, 

and common, striped, Risso’s and bottlenose dolphins may also be seen occasionally within the area. The 

occurrence of most cetacean species is generally higher during summer months. Cetacean species present in the 

proposed development area are generally distributed throughout the North Sea. 

Marine mammals can potentially be impacted by noise, contaminants and discharges, oil spills, collisions with 

vessels and any effects on prey availability associated with oil and gas activities. Potential sources of acoustic 

disturbance from underwater noise generated during the proposed development include DP vessels, standby vessels 

and the installation of the pipeline and associated sub-sea structures. 

Seabirds 

Seabirds are vulnerable to oiling from surface oil pollution, which could cause direct toxicity through ingestion, and 

hypothermia as a result of the birds’ inability to waterproof their feathers. Certain birds, including guillemots, 

razorbills and puffins, are more vulnerable to oil spills in the moulting season, when they become flightless and 

spend a large amount of time on the water surface. 

Species commonly found in the offshore waters such as the proposed development area include fulmar, gannet, 

guillemot, razorbill, and kittiwake, and herring, great black-backed and lesser black-backed gull. In the proposed 

development area, the most sensitive times of the year is between July and November when seabird vulnerability to 

oil pollution is high. Vulnerability ranges from moderate to low for the remainder of the year. The overall seabird 

vulnerability to surface pollution in the area is moderate. 

Commercial Fishing Activity 

The relative value of fishing in the area of the proposed development is low. Demersal, pelagic and crustacean 

species are caught in the area. The total value of fish landed in the proposed development area (ICES 44F1 and 

43F1), was predominantly demersal species. 

The proposed development has the potential to interfere with fishing activities, for example as a result of exclusion 

zones. There is also the potential risk of the accidental snagging of fish nets on sub-sea structures associated with 

development. 

Shipping Activity 

Shipping traffic comprises 12 routes which pass within 10 nm of the proposed development with approximately 624 

vessels per year (equivalent to 1 to 2 vessels per day). Any shipping traffic in the area will consist mainly of fishing 

vessels, merchant vessels and offshore industry vessels. 

Key to Level of Sensitivity / Activity 

Very high 

High 

Moderate 

Low 






5 EVALUATION OF POTENTIAL ENVIRONMENTAL IMPACTS 


This section evaluates the relative significance of the potential environmental impacts that 

might arise as a result of the various activities associated with the proposed Bardolino 

Development. Its purpose is to identify those potential impacts that might cause significant 

effects, so that they can be more fully assessed and mitigated as necessary. Potential effects 

are evaluated in terms of the environmental impact or risk of the activity, the sensitivity of the 

location (where applicable) and the time of year the activity is taking place. This evaluation 

has been carried out for routine, non-routine and accidental/emergency events. 

The proposed Bardolino Development has the potential to cause environmental impact in 

several different ways, including physical disturbance of the seabed, emissions of gases to 

the atmosphere, discharges of liquids and contaminants to sea, and the generation of wastes 

for disposal onshore. These effects could occur throughout the life of the project, from 

construction through installation and commissioning, to production operations. The 

environmental effects of decommissioning the Bardolino facilities are not assessed in this ES. 

As required under The Petroleum Act, 1998, they would be formally assessed towards the 

end of field life, and such an assessment would be undertaken in accordance with the 

legislation and policy in force at that time. 

5.2 IDENTIFICATION OF POTENTIAL ENVIRONMENTAL IMPACTS 

The first step in the assessment of significance has been to identify the different activities or 

sources of potential environmental impact or risk associated with each phase of the proposed 

Bardolino Development, and the receiving environmental media that could be affected (Table 

5.1). 

April 2008 Page 5-1


Table 5.1: Sources of potential environmental impacts associated with the Bardolino 

Development 

Activity / Source of Potential Impact 

Well Engineering 

Receiving Environmental Media 

Noise disturbance from drilling �� 

Physical presence of rig and support vessels (including anchors) �� 

Discharge of WBM and/or cuttings �� 

Disposal of LTOBM and/or cuttings �� 

Discharges from well cementing and completion �� 

Gaseous emissions from well clean-up and testing �� 

Gaseous emissions from power generation on rig or vessels �� 

Discharge to sea of drainage water or sewage from rig �� 

Disposal of solid waste from rig �� 

Installation and Commissioning of Pipelines, Umbilical, Manifold and Valve Skid 

Installation of pipelines and umbilical �� 

Physical presence of pipelines, umbilical, manifold and valve skid �� 

Physical presence of mattress protection around the manifold, tree 

and valve skid 

Noise from piling operations during installation of manifold and 

valve skid 


Climate 

Air Quality 

Water Quality 

Seabed 

Benthic Fauna 

Plankton 

Fish and Shellfish 

Marine Mammals 

Seabirds 

Fisheries 

�� 

�� 

Physical presence of installation and commissioning vessels �� 

Gaseous emissions from power generation on installation and 

commissioning vessels 

Discharge to sea of drainage or sewage from installation and 


�� 

�� 

Disposal of solid waste from installation and commissioning vessels �� 

Commissioning and testing of pipelines, umbilical, manifold and 

valve skid 

�� 

Noise from installation and commissioning vessels �� 

Rock dumping �� 

Wastage of anodes �� 

Shipping 

Onshore


Table 5.1, continued: Sources of potential environmental impacts associated with the 

Bardolino Development 


Production, Utility and Maintenance Operations 

Receiving Environmental Media 

Discharge of produced water at Nelson �� 

Use of production chemicals �� 

Impacts associated with maintenance vessels �� 

Accidental / Emergency Events 

Release of hydrocarbons during drilling, installation, well blow-out, 

well-test or other well incidents 


Climate 

Air Quality 

Water Quality 

Seabed 

Benthic Fauna 

Plankton 

Fish and Shellfish 

Marine Mammals 

Seabirds 

Fisheries 

�� 

Leak or spillage of chemicals from the drilling rig �� 

Pipeline failure �� 

Ship collision �� 

Notes: Refer to Table 5.4 for significance of these impacts 

Shipping 

Onshore


5.3 ASSESSMENT OF IMPACTS 

Having identified the activities/events that might give rise to environmental impact, the 

predicted effect of activities associated with the proposed Bardolino Development on the 

receiving environmental receptors has been assessed and is detailed in Table 5.2. The 

assessment of the potential effects on the environment has been made using information and 

data on the following issues: 

• The concentration of pollutants or the magnitude of disturbance associated with 

waste streams / disturbances, using the data presented in Section 3. 

• The manner in which the severity of an effect might vary depending on the location 

and timing of the activity, using the data presented in Section 4. Effects may vary in 

significance according to the sensitivity of the environmental features present and the 

time of year in which the activity is being carried out. 

• The nature, and where possible scale and duration, of the physical, chemical, 

biological and social / economic effects caused by the releases / disturbances once in 

the environment. This assessment has been made by reference to the accumulated 

research and survey work on the environmental effects of the offshore industry, 

making reference, where possible, to concentration levels or magnitudes that have 

known environmental effects. 

The results of the evaluation of the significance of the impacts are presented in Table 5.4, 

using the predefined significance criteria shown in Table 5.2. Impacts that fall into the 

categories described as: “none”, “negligible” and “minor” have been assessed to be nonsignificant. 

Table 5.3 provides justifications for the assessment of these non-significant 

impacts, which have been excluded from further investigation within the ES. Any impacts that 

were classified as being of “moderate” or greater significance are considered in more detail in 

Section 6. 

Table 5.3 also identifies the control and mitigation measures which would be in place to 

reduce and / or avoid each identified potential effect associated with the proposed Bardolino 

Development. In addition to specific mitigation measures detailed in Table 5.3 all activities 

would be covered by Shell’s CMS and the following systems: 

• HSE Management of Contractors 

• Contractual clauses on pollution control 

• Drilling Rig Safety Case 

• Installation Safety Case 

• Contractor HSE Interface Documents 

Page 5-4 April 2008


Table 5.2: Criteria used to assess the significance of potential impacts 

Colour 

Code 

Level of 

Environmental 

Impact 

Severe 

Major 

Moderate 

Minor 

Negligible 

Definition 

• Change in ecosystem leading to long term (>10 years) damage 

and poor potential for recovery to a normal state. 

• Likely effect on human health. 

• Long term loss or change to users or public finance. 

• Change in ecosystem or activity over a wide area leading to 

medium term (>2 years) damage but with a likelihood of recovery 

within 10 years. 

• Possible effect on human health. 

• Financial loss to users or public. 

• Change in ecosystem or activity in a localised area for a short 

time (


Table 5.3: Evaluation of the significance of potential environmental effects associated with the Bardolino Development 

Activity / Source of 

Potential Impact 

1. Well Engineering 

1.1 Noise disturbance 

from drilling 

1.2 Physical presence 

of the rig and support 

vessels (including 

anchors) 

Possible Environmental Effects Prevention, Control & Mitigation Measures Significance Rating (refer Table 5.3 for key) 

• The noise associated with drilling 

activities, and the operation of the rig and 

support vessels, may cause disturbance to 

marine mammals. 

• The physical presence of the drilling rig 

and support vessels may restrict access in 

the area for other users of the sea (e.g. 

fishing vessels and shipping). 

• The placement of the anchors on the 

seabed may result in anchor mounds 

being formed due to the clay sediment 

type in the Bardolino area. 

• Machinery and equipment would be in good 

working order and well-maintained. 

• A 500m safety zone around the rig would 

prohibit fishing and other vessel activity. 

• Consultation would be carried out with other 

users of the sea, and notification given to 

mariners of the rig movement and drilling 

location. 

• During drilling, the standby vessel would 

monitor the activity of all other vessels in the 

vicinity of the drilling site. 

Minor – See Section 6 

• The noise generated by the drilling rig would be loudest at 

low- to mid-frequencies (20-1,000Hz) and would be 

similar to that generated by medium/large merchant 

vessels. 

• The area of sea in which marine mammals might 

experience noise levels that could cause an avoidance 

reaction would be limited to a relatively small around the 

drilling rig. 

• The densities of marine mammals (in particular harbour 

porpoise) in the Bardolino area are low when compared to 

other areas of the North Sea. 

Moderate – see Section 6 

• The levels of shipping and fishing at Bardolino are both 

low, so only a small number of vessels might be 

inconvenienced. 

• The benthic communities at the well site are widely 

distributed over large areas of central 

• The well is located more than 50 km from the proposed 

dSAC boundary for the Braemar pockmark. No unusual 

seabed features were identified during the site-specific 

surveys of the Bardolino area. 

• The presence of residual anchor mounds once the rig has 

moved away may present a hazard to fishermen. 

Page 5-6 April 2008




1. Well Engineering, continued 

1.3 Discharge of WBM 

and / or cuttings 

1.4 Disposal of LTOBM 

and / or cuttings 

1.5 Discharges from 

well cementing and 

completion 

Possible Environmental Effects 

• The permitted discharge of approximately 

863 tonnes of water-based mud and 

cuttings over a drilling period of about 

110 days could result in a short-term 

impact on water quality and localised 

smothering of seabed and biota. 

• The base case is that all LTOBM and 

cuttings would be contained and shipped 

to shore for reprocessing / disposal. 

There would therefore be no impact on 

the marine environment from this activity. 

• Some cementing chemicals could 

accidentally escape to the seabed at the 

wellheads. 

Prevention, Control & Mitigation Measures 

• Chemicals would be selected in order to 

minimise hazards to the environment, in 

accordance with Offshore Chemical 


• Cuttings would be cleaned by shale shakers 

prior to discharge. 

• Any contingency LTOBM cuttings would be 

shipped to shore for reprocessing and would 

not be discharged to sea. 

• All LTOBM cuttings would be contained and 

shipped to shore for reprocessing. 

• Chemicals would be selected in order to 

minimise hazards to the environment in 



• The amounts of chemicals and cement required 

would be calculated accurately and the 

operations carefully planned. 

Significance Rating (refer Table 5.3 for key) 

Moderate – See Section 6 

• The WBM used would contain as large a number of 

chemicals that are PLONOR and of low Hazard Quotient as 

practicable. 

• The discharge of WBM cuttings from the well would form 

a localised accumulation immediately around the 

discharge point. Only a very small proportion of the 

existing benthos would be smothered. 

• The benthic communities around the proposed Bardolino 

drilling location have an extensive distribution in the North 

Sea, and there are no unique or protected species in the 

area. 

• Areas of seabed impacted by the accumulation of WBM 

cuttings would be readily re-colonised by migration and 

settlement of benthic fauna from adjacent unaffected 

areas once the discharge of cuttings ceased. 

Negligible 

• All LTOBM cuttings would be contained and shipped to 

shore for treatment and reprocessing. 

• Onshore treatment and disposal of LTOBM would have a 

negligible effect on the existing onshore facilities and 

infrastructure. 

Negligible 

• The chemicals would be bound in an inert matrix and 

therefore would not be bio-available. 

• Experience has shown that only small amounts of cement 

escape at the seabed. Mica and sea dye are often used to 

indicate the levels of cement returns. 

April 2008 Page 5-7





1.6 Gaseous emissions 

from well clean-up and 

testing 


from power generation 

on drilling rig or vessels 

1.8 Discharge to sea 

of drainage water or 

sewage from the 

drilling rig 

Possible Environmental Effects Prevention, Control & Mitigation Measures 

• The combustion of reservoir fluids flowed 

during clean-up for each well would 

release gaseous emissions to the 

atmosphere. These could contribute to 

global processes such as global warming, 

acid rain deposition and low level ozone 

formation (cumulative and trans-boundary 

effects). 

• The burning of diesel fuel on the drilling 

rig and support vessels would release 

gaseous emissions to atmosphere. 

• This could lead to deterioration in air 

quality in the immediate vicinity of the 

exhaust outlets. 

• Gaseous emissions could also contribute 

to global processes such as global 

warming, acid deposition and low-level 

ozone formation (cumulative and transboundary 

impacts). 

• The discharge of cleaned oily drainage 

water from the rig’s machinery space 

drainage system would introduce oil into 

the sea. 

• The discharge to sea of macerated 

sewage from the rig’s domestic sewage 

system, would cause localized organic 

enrichment in the vicinity of the discharge 

location. 

• The well clean-up procedures would aim to 

minimise the amount of product flowed. It is 

planned that each combined clean-up and welltest 

would take no longer than 48 hours at a 

maximum of 15,000 bbl of oil with an expected 

GOR of 870 scf/bbl. 

• No extended well test or clean-up is planned 

and it is likely that the quantities flared will be 

no more that 8,000 bbls. 

• Highly efficient flare burners would be used, to 

minimise drop-out and reduce the formation of 

black smoke. 

• All engines, generators and other combustion 

plant would be well maintained and correctly 

operated, to ensure that they were working as 

efficiently as possible to minimise emissions. 

• There would be systems in place on the rig to 

ensure that drainage discharges complied with 

MARPOL. This requires that the rig must be 

fitted with oil-water separation and filtration 

equipment, to ensure that the concentration of 

oil in any discharged water is less than 15ppm. 

• The rig would have UK or International Oil 

Pollution Prevention certification for its drainage 

systems. 

• Sewage would be macerated on the rig to aid 

biological breakdown once discharged into the 

sea. 

• Significance Rating (refer Table 5.3 


for key) 

Moderate – See Section 6 

• In the exposed and generally windy conditions offshore, 

the gaseous emissions would disperse rapidly after 

release, thus ensuring there was no local cumulative 

effect. 

• The emissions from well clean-up and testing would make 

a very small contribution to world-wide levels of 

atmospheric contaminants, when compared to other 

industrial sources. 

Minor – See Section 6 




effect. 

• The gaseous emissions that would arise from power 

generation processes on the drilling rig and associated 

vessels would make a very small contribution to worldwide 

levels of atmospheric contaminants, when compared 

to other industrial sources. 

Minor 

• Only small volumes of drainage water would be 

discharged from the rig’s machinery space, and the 

concentration of oil would be low. 

• In the generally energetic conditions offshore in the North 

Sea, such small volumes of water would be rapidly 

dispersed and diluted. 

• At the offshore location, the small volumes of macerated 

sewage would be rapidly dispersed in the water column 

and be insignificant in terms of organic enrichment.





1.9 Disposal of solid 

waste from the drilling 

rig 


• The permitted disposal to sea of 

macerated food waste could lead to very 

localised organic enrichment of the water 

column around the point of discharge. 

• The treatment and disposal of solid 

wastes at onshore waste treatment and 

landfill sites could result in impacts to the 

air quality, hydrology, flora and fauna, 

and socio-economic aspects of such sites. 

• Food waste would be macerated as required by 

MARPOL and Merchant Shipping 

(Prevention of Pollution by Garbage) 

Regulations 1998; this would aid its dispersal 

and decomposition in the water column. 

• All other waste would be segregated and 

contained, and then shipped to shore for 

recycling or disposal by a licensed company in 

full compliance with UK waste legislation and 

Duty of Care. 

• Shell regularly audits its approved onshore 

waste disposal contractors, to ensure all 

procedures and legal requirements are adhered 

to. 


Minor 

• The particles of food waste would be





2. Installation and Commissioning of Pipelines, Umbilical, Manifold and Valve Skid 

2.1 Installation of 

pipelines and umbilical 


of pipelines, umbilical, 

manifold and valve skid 


of mattress protection 

around the manifold, 

tree and valve skid 

• Laying the pipelines and umbilical on the 

seabed would physically disturb the 

seabed sediments and cover part of the 

benthic community. 

• Trenching both trenches will result in a 

temporary deterioration in water quality 

during and after the use of the trenching 

plough. 

• Laying the pipelines and umbilical on the 

seabed would physically disturb the 

seabed sediments and cover part of the 

benthic community. 

• Until the pipeline becomes buried, it could 

present a snagging risk for bottom-towed 

fishing gear. 

• Placement of mattresses on the seabed 

would physically disturb the seabed 

sediments and cover part of the benthic 

community. 

• Approximately 130 mattresses would be 

required to stabilize the two transition 

zones at either end of the pipeline. These 

would cover at total seabed area of 

approximately 2,340 m 2 

• The area of seabed affected by the trenching 

and burial of the pipelines and the umbilical 

would be limited to one trench of width 6.2 m 

and a second trench of approximately 2 m 

width, resulting in a total affected area of 0.016 

km 2 . 

• Other users of the sea, including commercial 

fishermen, would be consulted about the 

proposed pipeline and umbilical routes during 

the detailed planning stage. 

• The area of seabed affected by the trenching 

and burial of the pipelines and the umbilical 

would be limited to one trench of width 6.2 m 

and a second trench of approximately 2 m 

width, resulting in a total affected area of 0.016 

km 2 . 

• Other users of the sea, including commercial 

fishermen, would be consulted about the 

proposed pipeline route during the detailed 

planning stage. 

• Covering the pipelines by backfilling and/or 

rock dumping will reduce any potential 

snagging risk for bottom-towed fishing gear. 

• The area of seabed affected would be 

approximately 2,340 m 2 

• Mattresses would be designed to minimise the 

risk of snagging from bottom-towed fishing 

gear. 


• Disturbance to benthic communities would be localised to 

a very small area of approximately 0.016 km 2 along the 

pipeline and umbilical routes. 

• The benthic communities found along the pipeline and 

umbilical routes are widely distributed over large areas of 

central North Sea; there are no unique or protected 

species along the routes. 

• Suspended sediments from trenching and ploughing 

would settle rapidly and be dispersed, the deterioration in 

water quality would be temporary and localised. 


• Disturbance to benthic communities would be localised to 

a very small area, of approximately 0.016 km 2 along the 

pipeline and umbilical routes. 

• Clean sediments which are disturbed will be quickly recolonised 

by natural fauna, from adjacent, undisturbed 

sites. 

• Inconvenience to other users of the sea would be 

localised and temporary. Fishing effort in the area is low. 

Shipping activity in the area is moderate. 

• No potentially sensitive habitats protected under Annex I 

of the EU Habitats Directive, have been identified at the 

Bardolino location or along the pipeline route corridor. 


Minor 

• The mattresses would have a footprint of approximately 

2,340 m 2 on the seabed. 

• Clean sediments which are disturbed will be quickly 

recolonised by natural fauna, from adjacent, undisturbed 

sites. 

• The benthic community is typical of that found over large 

areas of this part of the central North Sea; no unique or 

protected species are present.






2.4 Noise from piling 

operations during 

installation of manifold 



of installation and 


• The underwater noise generated during 

piling operations to install the manifold 

and valve skid will have the potential for 

the temporary disturbance of marine 

mammals and fish in the vicinity. Piling 

noise could cause temporary behavioural 

changes in or result in temporary effects 

on hearing. 

• The presence of the DP installation and 

commissioning vessels moving slowly 

along the pipeline route may cause 

interference to other users of the sea, 

including commercial fishing boats. 

• Shell will follow its piling procedure which has 

been discussed and agreed with the JNCC. A 

Marine Mammal Observer will be used to 

ensure that the area is clear of marine 

mammals before piling commences and a soft 

start will be used. Piling will only take place in 

daylight hours. 

• The main piling operation, which is likely to last 

approximately 24 hours in two phases of 

approximately 12 hours each, will be carefully 

planned and managed to minimise effects on 

marine mammals. 

• Other users of the sea would be consulted 

about the proposed operations during the 

detailed planning stage. 

• The proposed programme and pipeline and 

umbilical routes would be notified to sea users 

in “Notices to Mariners”. 

• The pipeline laying and umbilical laying 

programme would be carefully planned. In the 

field, the programme of moving the installation 

vessels along the route would be carefully 

managed and coordinated so that it was 

completed as quickly and efficiently as possible. 

In support of this, “interface document(s)” 

would be set up between the contractors and 

Shell, stipulating roles and responsibilities of 

each party. 

• A dedicated guard vessel would be on location 

throughout the pipelaying and umbilical 

operations to ensure that all traffic was aware 

of the presence of the pipelaying and umbilical 

laying vessels. Vessels other than those 

involved in the operation would not be 

permitted to enter the safety zone. 


• The densities of marine mammals in the period of the 

proposed installation operations are relatively low. 

• Modelling indicates that only animals within a few 

kilometres of the piling operations would be likely to be 

exposed to noise levels that might result in temporary 

hearing change. 

• Shell will follow piling procedures agreed with JNCC 

(Appendix 4) 


Minor 

• The pipe-laying activities would be limited to a period of 

about 6 weeks. 

• Inconvenience to other users of the sea would be very 

localised and temporary. The value of fisheries in the 

area is “low”, and the effect of a temporary loss of access 

to a small proportion of this area as the pipe laying and 

umbilical laying spread moves along the route would 

therefore be negligible. 

• The level of commercial shipping in the area is moderate.







from power generation 

on installation and 


2.7 Discharge to sea 

of drainage or sewage 

from installation and 


2.8 Disposal of solid 

waste from installation 

and commissioning 

vessels 

2.9 Commissioning 

and testing of 

pipelines, umbilical, 

manifold and valve skid 

• The burning of diesel fuel on the 

installation and commissioning vessels 

would release gaseous emissions to 

atmosphere. 








impacts). 






Minor 




effect. 

• Please refer to item 1.8 • Please refer to item 1.8 Minor: Please refer to item 1.8 

• Please refer to item 1.9 • Please refer to item 1.9 Minor: Please refer to item 1.9 

• The permitted discharge to sea of pipeline 

testing and commissioning chemicals 

could affect water quality at the discharge 

site. 

• Only the types and amounts of chemicals 

essential to demonstrate the integrity and 

fitness of the pipeline would be used. 

• The chemicals would be carefully selected so as 

to minimise potential environmental effects, in 




generation processes on the vessels would make a very 

small contribution to world-wide levels of atmospheric 

contaminants, when compared to other industrial sources. 

Minor 

• The concentrations of chemicals in the pipeline during 

testing and commissioning would be low. 

• Assessment under the Offshore Chemical Regulations 

2002 will have demonstrated that the discharge of such 

chemicals would not be likely to have a significant 

environmental effect.






2.10 Noise from 

installation and 



of contingency rock 

dump 

• Noise from the thrusters of the 

dynamically positioned (DP) installation 

and commissioning vessel may result in 

underwater noise levels that would cause 

temporary disturbance to marine 

mammals. 

• Approximately 20,000 tonnes of graded 

rock would be required to stabilise the 

piggybacked pipelines along open trench 

to prevent upheaval buckling. 

• The engines and other equipment on the 

installation and commissioning vessels would 

be well-maintained, and this would help to 

reduce the level of noise emitted. 

• Use of a fall-pipe on the rockdump vessel, and 

ROV supervision will ensure the rockdump is 

placed in the correct position. 

• Location and profile of rockdumps would be 

made available to fishermen and fishing 

interests. Profile will be designed to minimise 

the risk of fishing gear snagging. 

• Rockdump in the open trenches will become 

naturally backfilled by surrounding sediments. 


Minor 

• The densities of marine mammals in the Bardolino area 

(in particular harbour porpoise) is moderate to high when 

compared to the other areas of the North Sea. 

• The pipe-laying activities would be limited to a period of 

about 6 weeks . 

• The underwater noise levels that would be created by the 

DP lay vessels and other vessels would be similar to that 

created by medium/large merchant vessels. 

• Modelling shows that at the frequencies to which the key 

marine mammals are most sensitive, noise levels 

sufficient to cause avoidance reactions would extend to 

only a few kilometres around the pipelaying and umbilical 

laying vessel spread. In such circumstances, very small 

numbers of marine mammals would be exposed to 

disturbing levels of noise. 

• The noise from the DP pipelay and umbilical lay vessels 

and other vessels would not start suddenly, would vary in 

intensity, and would move progressively along the 

pipeline route. Marine mammals would therefore be 

unlikely to be exposed suddenly to very loud noise, and 

could move away if noise levels increased gradually to 

levels that caused disturbance. 

Moderate 

• Clean sediments which are disturbed will be quickly recolonised 

by natural fauna, from adjacent, undisturbed 

sites. 

• The benthic community is typical of that found over large 

areas of this part of the central North Sea; no unique or 

protected species are present.





3. Production, Utility and Maintenance Operations 

3.1 Discharge of 

produced water at 

Nelson 

3.2 Use of production 

chemicals 

• Produced water containing dispersed oil 

from Bardolino will be discharged at the 

Nelson installation. The total quantity 

discharged will increase as a result of the 

project. Increased levels of dispersed oil 

in the produced water discharged could 

have an impact on seabirds, plankton and 

fish in the vicinity of the installation. 

• The use and possible discharge of 

additional production chemicals could 

cause impact to the marine environment. 

• The use of additional corrosion inhibitor 

may have an adverse effect on oil in 

produced water separation which could 

have an impact on the marine 

environment. 

• The majority of produced water at Nelson is reinjected 

using the Produced Water Re-injection 

(PWRI) system. Bardolino produced water will 

be generated through Nelson as production 

from Howe declines leading to a minor net 

increase in discharge. 

• All production chemicals would be selected and 

assessed according to the Offshore Chemical 

Regulations 2002, in order to minimise 

impacts to the marine environment. 


• The Bardolino project will lead to a net increase in the 

quantity of produced water containing dispersed oil 

discharged at Nelson. 

• The quantity of produced water from Bardolino will 

represent only around 1% of the total produced water 

handled at the Nelson platform. 

• Due to limits on produced water handling capacity at 

Nelson an additional volume of produced water equal to 

that produced from Bardolino will be discharged to sea. 


• The use of additional corrosion inhibitor in combination 

with the fine solids that will be present in the Bardolino 

produced fluids has the potential to reduce the 

effectiveness of oil in produced water separation on 

Nelson and increase the quantity of dispersed oil 

discharged to sea. Any increase in dispersed oil levels will 

be managed in accordance with the conditions of the 

Nelson permit under the Offshore Petroleum Activities (Oil 

Pollution Prevention and Control) (OPPC) Regulations 

2005. 






3. Production, Utility and Maintenance Operations, continued 

3.3 Impacts associated 

with maintenance 

vessels. 

• The burning of diesel fuel on the vessels 

would release gaseous emissions to 

atmosphere. 








impacts). 

• Discharge to sea of drainage water and 

sewage from vessels could lead to 

localized organic enrichment in the vicinity 

of the discharge location. 

• The use of onshore facilities for the 

treatment and disposal of waste could 

lead to a variety of onshore impacts. 





• There would be systems in place on the vessels 

to ensure that drainage discharges complied 

with MARPOL. This requires that the vessels 

must be fitted with oil-water separation and 

filtration equipment, to ensure that the 

concentration of oil in any discharged water is 

less than 15 ppm. 

• Sewage would be macerated on the vessels to 

aid biological breakdown once discharged into 

the sea. 

• Food waste would be macerated as required by 

MARPOL and Merchant Shipping 

(Prevention of Pollution by Garbage) 

Regulations 1998; this would aid its dispersal 

and decomposition in the water column. 

• All other waste would be segregated and 

contained, and then shipped to shore for 

recycling or disposal by a licensed company in 

full compliance with UK waste legislation and 

Duty of Care. 

• Shell regularly audits its approved onshore 

waste disposal contractors, to ensure all 

procedures and legal requirements are adhered 

to. 

Negligible 

• All the maintenance activities would be carried out within 

the 500 m exclusion zone. 




effect. 


generation processes on the vessels would make a very 

small contribution to world-wide levels of atmospheric 

contaminants, when compared to other industrial sources. 

• Only small volumes of drainage water would be 

discharged from the rig’s machinery space, and the 

concentration of oil would be low. 

• In the generally energetic conditions offshore in the North 

Sea, such small volumes of water would be rapidly 

dispersed and diluted. 

• At the offshore location, the small volumes of macerated 

sewage would be rapidly dispersed in the water column 

and be insignificant in terms of organic enrichment. 

• The particles of food waste would be




4. Accidental / Emergency Events 

4.1 Release of 

hydrocarbons during 

drilling, installation, 

well blow-out, well test 

or other well incidents. 


• Creation of an oil sheen or oil slick on the 

sea surface around point of release. 

Possible subsequent movement and 

spreading of oil slick from original site of 

release. 

• The effects of any accidental spill would 

depend on the type of oil spilled, the size 

of the spill, the prevailing metocean 

conditions, and the actions taken in 

response to the spill. 

• All offshore operations would be carefully 

planned to minimise the likelihood of accidents, 

including those that might give rise to oil leaks 

and spills. 

• There will be specific procedures in place for 

bunkering (refuelling) the drilling rig offshore, if 

required. 

• In the event of an oil spillage to sea, the 

Nelson Field Oil Spill Contingency Plan (OSCP) 

(including Bardolino) would be activated. 

• The integrity of the well would be monitored; 

there would be safety valves on production 

trees. 

• The wells would be controlled in accordance 

with principles and procedures laid out in the 

current Shell Well Engineering Information 

System, in order to ensure that pressures were 

contained securely. 

• The well/pressure control equipment would be 

regularly tested. The drilling rig would be 

equipped with a blow-out preventer (BOP), and 

the BOP and related equipment would be 

pressure tested every 21 days with 

intermediate function tests every 8-13 days 

• The crew of the drilling rig would be given 

environmental awareness training prior to the 

start of the drilling programme. 

• Specific procedures would be in place to 

manage and control bunkering and the transfer 

of base oil, in order to minimise the likelihood 

of accidental spills. 

• Key well site personnel are trained and 

certified according (IWCF) international Well 

Control forum. Well design has been designed 

according Shell EPE technical standards. Risks 

for well control are as low as reasonable 

practicable. 


• All offshore operations would be carefully planned to 

minimise the likelihood of accidents, including those that 

might give rise to oil leaks and spills. 

• It is therefore very unlikely that significant amounts of oil 

would escape or be spilled at the Bardolino site. 





4. Accidental / Emergency Events, continued 

4.2 Leak or spillage of 

chemicals from the rig 

4.3 Failure of the 

pipelines 


• The accidental release of chemicals could 

lead to a deterioration in water quality at 

the site of release, and possible toxic 

effects on marine life. 

• There would be specific procedures on the 

drilling rig for the storage, handling and use of 

all chemicals. 

• The inventory of chemicals in the drilling rig 

would be sufficient only for the Bardolino 

drilling programme. 

• The chemicals on board would be carefully 

selected so as to minimise potential 

environmental effects, in accordance with 

Offshore Chemical Regulations 2002. 

• Please refer to item 4.1 • Please refer to item 4.1 

• The pipeline would be designed, fabricated, 

installed and tested to ensure that it complied 

with the required specification and expected 

lifetime. 

• The pipeline would be regularly monitored by 

means of internal inspection to confirm its 

integrity. 

• Emergency shutdown valves would activate to 

minimise uncontrolled release of produced 

fluids 

• In the event of an oil spillage to sea, the 

Nelson Field Oil Spill Contingency Plan (OSCP) 

(including Bardolino) would be activated. 


Minor 

• Procedures would be in place to reduce the likelihood of 

accidental spillages or releases to very low levels. 

• The chemicals that would be present would be of low 

hazard to the environment, and only small volumes would 

be stored on the drilling rig. 


• Please refer to item 4.1 

• With the monitoring and control procedures that would be 

in place, any leak or failure in the pipeline would be 

quickly identified, and the pipeline would be shut down 

rapidly, thus minimising the amount of produced fluid 

released.




4. Accidental / Emergency Events, continued 


4.4 Ship collision • A vessel could collide with the drilling rig 

or installation vessel and this could result 

in: 

� the damage or loss of the vessel 

� the spillage of fuel oil from the 

vessel. 

• Mariners and other users of the sea would have 

been consulted during the planning of the 

Bardolino development. 

• The location of the drilling rig would be notified 

to mariners, and there would be a statutory 

500m safety zone around the platform. 

• The operation of the drilling rig would be 

covered by the rig OSCP and the Nelson field 

OSCP. The standby vessel for the rig would be 

equipped with appropriate dispersants to 

ensure that rapid and effective action can be 

taken to minimise the potential impact of any 

spill. 


• It is very unlikely, given the control that would be in 

place, that there would be a collision that would result in 

the release or escape of a significant amount of 

hydrocarbons from the platform. 

• The drilling operations at Bardolino would be covered by 

the Nelson field OSCP and the rig OSCP. 



5.4 SIGNIFICANT IMPACTS ASSESSMENT RESULTS 

A summary of environmental impacts and their predicted significance is presented in Table 

5.4 (refer to Table 5.3 for definition of significance ratings). 

All of the impacts which were classified during this assessment as being more significant than 

“minor” are discussed in greater detail in Section 6. 

Table 5.4: Results of the assessment of significance for all effects arising from the 

Bardolino Development 


Well Engineering 

Noise disturbance from drilling 

Physical presence of rig and support vessels (including 

anchors) 

Discharge of WBM and/or cuttings 

Disposal of LTOBM and/or cuttings 

Discharges from well cementing and completion 

Gaseous emissions from well clean-up and testing 

Gaseous emissions from power generation on rig or vessels 

Discharge to sea of drainage water or sewage from rig 

Disposal of solid waste from rig 

Installation and Commissioning of Pipelines, Umbilical, Manifold and Valve Skid 

Installation of pipelines and umbilical 

Physical presence of pipelines, umbilical, manifold and valve 

skid 

Physical presence of mattress protection around the manifold, 

tree and valve skid 

Noise from piling operations during installation of manifold and 

valve skid 

Physical presence of installation and commissioning vessels 

Gaseous emissions from power generation on installation and 


Discharge to sea of drainage or sewage from installation and 


Disposal of solid waste from installation and commissioning 

vessels 

Commissioning and testing of pipelines, umbilical, manifold 


Noise from installation and commissioning vessels 

Rock dumping 


Severe 

Major 

Moderate 

Minor 

Negligible 

None 

Beneficial



Wastage of anodes 

Production, Utility and Maintenance Operations 

Discharge of produced water at Nelson 

Use of production chemicals 

Impacts associated with maintenance vessels 

Accidental / Emergency Events 

Release of hydrocarbons during drilling, installation, well blowout, 

well test or other well incidents 

Leak or spillage of chemicals from the drilling rig 

Pipeline failure 

Ship collision 


Severe 

Major 

Moderate 

Minor 

Negligible 

None 

Beneficial


6 ASSESSMENT OF POTENTIALLY SIGNIFICANT IMPACTS 


This section discusses in greater detail the potential impacts (including potential cumulative, 

trans-boundary and global impacts), which were identified in the assessment process 

(Section 5) as being of greatest significance to the environment. These are: 



• the discharge of WBM and cuttings from the well; 

• the atmospheric emissions that would arise from the Bardolino development; 

• the local disturbance to the seabed caused by pipeline trenching and backfilling, rock 

dump stabilisation and mattressing; 

• the installation and physical presence of the subsea structures (manifold, tree and 

valve skid); 

• the underwater noise that would arise from the Bardolino development; and 

• the discharge of produced water at the Nelson platform. 

In addition, the potential for accidental hydrocarbon spillage is discussed in relation to the 

following scenarios, which are also considered as being of significance to the environment: 

• a spill of hydrocarbons during drilling, installation, well blow-out, well test or other well 

incidents; 

• a release as a result of pipeline failure; and 

• a spillage of diesel following the collision of a vessel with the drilling rig. 

April 2008 Page 6-1


6.2 THE PHYSICAL PRESENCE OF THE DRILLING RIG AND SUPPORT 

VESSELS (INCLUDING ANCHORING OF THE DRILLING RIG) 

6.2.1 Likely magnitude and duration 

Shell proposes to drill the Bardolino development well with Transocean’s semi-submersible 

drilling rig, the Arctic IV. The presence of the semi-submersible rig and support vessels 

during the drilling operations might result in some interference with commercial fishing or 

shipping in the area adjacent to the Bardolino location. A temporary safety exclusion zone 

with a radius of 500m centred on the semi-submersible drilling rig would be established for 

the duration of drilling operations, a period of 3 months. This would exclude commercial and 

fishing vessels from an area of approximately 0.8 km 2 . 

The semi-submersible drilling rig would be positioned over the drilling location with the aid of 

the three AHTVs, and would maintain its station by eight anchors in a pre-determined ‘anchor 

pattern’. In such a system, the anchors are attached to the drilling rig with a chain and cable 

combination; for each anchor line approximately 300m of chain would be in contact with the 

seabed, providing additional holding power. The use of anchors to position and moor the 

semi-submersible drilling rig would result in the physical disturbance of seabed sediments and 

benthic fauna in localised areas around the anchors (chains and wires) during deployment 

and retrieval. 

Depending on the nature of the seabed, anchors can create mounds up to 1 m high, and 

anchor chains lying on, and sweeping over, the sediments can create gouges and scour 

marks. Anchor mounds can form on clayey sediments, and because of the stiffness of clay 

they have the potential to become long-lived seabed features that may represent obstructions 

to mobile fishing gear deployed on the seabed. The anchoring conditions survey undertaken 

for the Bardolino well location indicated that seabed sediments comprise a veneer of sand 

with outcrops of clay (Gardline Geosurvey Limited, 2007). The shallow soils comprise soft 

to firm slightly sandy clay with occasional gravel, ranging from 25 m thickness in the west to 

being locally absent in the east (Gardline Geosurvey Limited, 2007). It is possible that 

persistent anchor mounds would be created on this type of sandy clay sediment. 

6.2.2 Impact on sensitive receptors and proposed or designated sites 

The presence of the semi-submersible drilling rig at the Bardolino location would result in a 

temporary loss of access to fishing grounds and a temporary inconvenience to commercial 

shipping in the area. The overall relative value of fisheries in the Bardolino development area 

is classified as “very low” to “low” for ICES rectangles 44F1 and 43F1 (SEERAD, 2008b) 

(Section 4.5.1). The relative fishing effort for demersal species, pelagic species, Nephrops 

and shrimp and shellfish is “very low” (SEERAD, 2008b). Demersal pair and otter trawling 

has dominated fishing effort in the Bardolino area between 2002 and 2006, with fishing 

activity occurring throughout the year (Section 4.5.1). The potential disturbance to 

commercial fishing from the drilling programme would be of a small-scale and would be very 

unlikely to impact on the economic value of the overall fishing activity in this area. The timing 

and nature of operations would be notified to other users of the sea and a dedicated guard 

vessel would be on location at Bardolino to ensure that all traffic was aware of the presence 

of the drilling rig. 

The distribution and abundance of benthic organisms in the North Sea is determined largely 

by latitude, water depth and sediment type. Results from biological surveys carried out in the 

general vicinity of the Bardolino development show that the infauna is typically dominated by 

polychaete worms, while epibenthic species include the shrimp Crangon allmanni and the 

hermit crab Anapagurus laevis (Section 4.4.2). The macrofaunal communities of the 

proposed development area are largely homogenous and typical of sandy sediments in the 

central North Sea. No sensitive, rare or threatened benthic communities are known to exist in 

the vicinity of Bardolino. 

Anchor mounds and scours have the potential to cause disruption to benthic communities. 

The deployment and retrieval of anchors from the semi-submersible drilling rig would cause 

Page 6-2 April 2008


some direct impact on invertebrates living on and in the sediments, and such disturbance 

would occur within a relatively small area of seabed defined by the extent of the anchor 

pattern (approximately 1 km 2 ). This disturbance, however, will be small in comparison to the 

seabed disturbances already created by the fish trawling activities occurring with the area. 

Benthic communities in the development area are similar to those found throughout the 

surrounding area of the central North Sea and no rare species are known to occur in this 

area. 

The drilling rig would be anchored to the seabed for about 3 months, and the area of seabed 

that would be directly physically affected will be very small. If fish were to be displaced by the 

anchoring activities this would be temporary, and fish would be expected to rapidly return to 

the area once the initial installation of the semi-submersible drilling rig had been completed. 

The proposed drilling location coincides with spawning areas for mackerel, lemon sole, 

Norway pout and Nephrops. Spawning and nursery areas are widely dispersed across the 

North Sea, and the spawning and nursery phases for most fish species are dynamic features 

of their life history, which shift and change in accordance with prevailing temperatures and 

prey availability. Consequently, spawning and nursery grounds are rarely fixed in the same 

location from one year to the next (CEFAS, 2001). As a result, it is considered that the 

localised effects associated with the installation and presence of the drilling rig would not 

have a significant impact on fish spawning or nursery areas. 

The drilling period would last approximately 3 months, and during this time there would be 

restrictions on commercial shipping and fishing in the immediate area of the rig. These are 

not considered to be significant, however, because the restrictions would be short-term, 

fishing effort in the area (Section 4.5.1) is very low, and shipping activity in the area (Section 

4.5.2) is moderate overall for this area of the central North Sea. 

6.2.3 Contribution to transboundary, cumulative or global impacts 

The presence of the drilling rig would cause temporary inconvenience to commercial fishing 

and shipping. Fishing activity is regulated by quota, and the loss of access to fish in this small 

area would not significantly reduce the ability of fishermen to achieve their quotas, given the 

large area of available fishing grounds in the rest of ICES rectangles 44F1 and 43F1. The 

presence of the drilling rig would therefore not represent a cumulative impact on fishing or 

shipping. 

The proposed Bardolino development is approximately 40 km from the UK/Norway median 

line. The deployment and retrieval of anchors for the semi-submersible drilling rig would 

cause localised temporary disturbance and interference over an area of seabed estimated to 

be


project. Mariners will be advised of specific periods and locations in which vessel operations 

should be avoided. Contact information will be provided and details of guard vessels will be 

given. Guard vessels would be on station during the drilling operations to alert shipping and 

fishing vessels of potential navigational hazards. 

All the anchors would be completely removed from the seabed at the end of the drilling 

programme. 

Page 6-4 April 2008


6.3 DISCHARGE OF WATER-BASED MUD AND CUTTINGS FROM THE 

DEVELOPMENT WELL 


The quantity of cuttings generated during drilling is largely determined by the dimensions of 

the well, as well as by the type of rock formations through which the well is being drilled. The 

planned discharge route for mud and cuttings generated during each stage of the Bardolino 

well is given in Table 6.1. 

Because it is not technically feasible to install the riser before drilling the first sections of the 

well, it is estimated that approximately 875 tonnes of water-based mud drill cuttings from the 

36″ and 26″ top-hole sections of the well will be discharged directly onto the seabed, together 

with the seawater and bentonite sweeps. The mud and cuttings will accumulate on the 

seabed immediately around the well site. The area of seabed that might be covered by such 

an accumulation may be roughly estimated by assuming that all the cuttings exiting the well 

stay on the seabed (i.e. do not drift away in currents), and form a circular cone-shaped 

mound. If the density of the cuttings is taken as 1.5, then 863 tonnes represents 583m 3 , say 

600m 3 . If the maximum height of the final cone is taken as 2m at its centre, then the cone 

would have a radius of about 17m, and cover approximately 900m 2 of seabed at the well site. 

The 726 tonnes of LTOBM cuttings from the 17½”, 12¼”, 8½” and 6⅛” sections will be 

pumped up the riser and pass over a series of shale shakers to remove as much of the 

LTOBM as possible. Residual LTOBM will be recovered for re-conditioning and re-use. The 

remaining solid cuttings will be collected in containers and returned to the shore and disposed 

to landfill (Section 3.4.9). 

Table 6.1: Planned treatment and disposal of drilling mud and cuttings from the 

Bardolino well 

Hole section 

(inches) 

Mud type Disposal 

36 Seawater and bentonite sweeps 299 direct to seabed 

26 Seawater and bentonite sweeps 564 direct to seabed 

17½ LTOBM 598 tonnes skip and ship 

12¼ LTOBM 204 tonnes skip and ship 

8½ LTOBM 20 tonnes skip and ship 

6⅛ LTOBM 8 tonnes skip and ship 

The main environmental impacts that may arise from the discharge of WBM and cuttings to 

the seabed are: 

• the possible creation of a localised cuttings mound, which would result in the 

smothering of benthic fauna and fish spawning grounds; and 

• the release of the drilling and cementing chemicals, which could be hazardous to the 

organisms in the marine environment. 

The main environmental impacts of drilling muds are caused by the chemicals used to 

formulate WBM, which may be toxic to, and bioaccumulated by, benthic fauna. Drilling mud 

comprises a base fluid, weighting agents to control the fluid density, and primary chemicals 

that are used to give the mud the exact properties it needs to make it as efficient and safe as 

possible to drill the well in the given conditions. The exact formulation of the drilling mud has 

not yet been decided but all primary and contingency drilling mud chemicals to be used, and 

potentially discharged, during the drilling phase of the well would be detailed in the PON 15B 

in accordance with the Offshore Chemical Regulations 2002. 

April 2008 Page 6-5



The biological communities in the area are generally typical of sandy sediments in the central 

North Sea; infauna are typically dominated by polychaete worms, whereas epibenthic species 

include the shrimp Crangon allmanni and the hermit crab Anapagurus laevis (Section 4.4.2). 

The dominant species found during the Nelson survey undertaken in 2005 and 2006 were the 

polychaetes Paramphiome jeffreysii, Myriochele sp. A., Exogone hebes and the brittle star 

Ophiura affinis (Hartley Anderson, 2007). Benthic samples retrieved during seabed surveys 

undertaken within Quadrants 22 showed that benthic communities were homogenous 

throughout the area and typical of fauna found in undisturbed sediments of the central North 

Sea (UK Benthos 2000). Macrofauna of the area are largely homogenous and typical of 

sandy sediments in the central North Sea. Infauna was dominated by the tube-dwelling 

polychaete Myriochele oculata which is a common member of central North Sea sandy 

associations (IOE, 1990a, b; ERT, 1994a, b). Other species commonly found during the 

environmental surveys were the crustacean Eudorellopsis deformis, the echinoderm 

Amphiura filiformis, the cnidarian Cerianthus llyodii, the bivalves Chaetoderma nitidulum and 

Mysella bidentata and the polychaete worm Phoronis muelleri (IOE, 1990a). No sensitive, 

rare or threatened benthic communities are known to exist in the vicinity of Bardolino. 

Discharging the cuttings from the top-hole sections of the well directly onto the seabed would 

smother the sediments and associated fauna in a very small area of seabed immediately 

around the discharge point, and release pollutants into the sediments and the water column. 

In the short term, this would cause the mortality of some benthic organisms, create an area of 

habitat that is different to the surroundings and result in the temporary covering of the 

sediments and loss of habitat required for the benthic fauna. In the medium term, however, 

the local habitat is likely to return to the natural conditions. Habitat recovery would be 

promoted by: 

• the dispersion, dilution and breakdown of chemicals within the cuttings, which would 

occur in the current regime that exists in this part of the North Sea; 

• the spreading and natural dispersion of the cuttings which would result from sediment 

movement in the area and the current regime; and 

• bioturbation effects caused by the action of burrowing benthic organisms such as 

polychaetes and crustaceans (e.g. Tsutsumi et al., 1990; Chareonpanich et al., 1993; 

Chareonpanich et al., 1994; Hansen et al., 1999). 

Observations of the accumulation of cuttings during the drilling of tophole sections have 

shown that re-colonisation of the surface of cuttings by benthic animals can begin within 

minutes or hours. WBM cuttings discharged onto the seabed would be quickly recolonised by 

benthic fauna typical of the area. In a series of field experiments, Bakke et al. (1985) 

prepared trays of natural seabed sediment that were devoid of flora and fauna, and covered 

them with a 10mm layer of WBM slurry. These were returned to the sea and sampled 

periodically. Recolonisation of the material in the trays by diatoms, meiofauna and 

macrofauna started immediately. During real time observations of the accumulation of WBM 

around a well west of Shetland, infauna were observed to burrow up through the deposited 

cuttings within a few minutes after drilling ceased (Bakke et al., 1985). 

Most cuttings would settle within the immediate vicinity of the discharge point, but there is a 

possibility that very fine cuttings particles that remain in suspension in the water column may 

travel further. Any remaining WBM will be washed away from the cuttings and rapidly diluted 

to such low concentrations that no significant impact would be anticipated. Particles that 

travel in the water column are unlikely to be distinguishable from natural suspended solids. 

Maximum tidal currents in the development area may range between 0.26 and 0.39 m/s 

(UKDMAP, 1998) and play a significant role in defining the seabed bottom features by 

mobilising and restoring the surface sediments and incorporating the cuttings particles from 

drilling. In comparison to discharges of LTOBM, discharges of WBM generally result in wide 

dispersion of discharged cuttings and little accumulation of contaminants in sediments and 

biota (Daan and Mulder, 1996). At the Bardolino site, the effects on sediment and water 

biology of the discharge of WBM drill cuttings from the proposed well are therefore expected 

to be insignificant. 

Page 6-6 April 2008


Harbour porpoise is the only Annex II species which has been sighted in the close vicinity to 

the Bardolino development (Quadrant 22) (Section 4.4.4; UKDMAP, 1998). These are highly 

mobile and wide-ranging species, and the discharge of WBM mud and cuttings from the 

proposed development is unlikely to have any effect on them. 

If fish were displaced from the local area, they will rapidly return once drilling operations have 

ceased, although there could be very localised disturbance to seabed-spawning species. 

Nephrops, mackerel, lemon sole and Norway pout are known to spawn in the proposed 

development area. Mackerel, lemon sole and Norway pout all release their eggs into the 

water column to be fertilised, whereas Nephrops lay their eggs on the seabed and therefore 

may be at risk from discharges of WBM mud and cuttings. The proposed drilling activities are 

scheduled to occur between March and May 2009 (Section 3.3.2), and would coincide with 

the spawning periods for all four species. As described in Section 6.3.1, however, the area of 

seabed that is likely to be physically impacted by the discharge of WBM from the top-hole 

sections will be very small in relation to the known extent of spawning areas in this part of the 

North Sea. 

Nephrops live in burrows and lay eggs on the seabed, and are therefore potentially 

susceptible to the effects of the discharge of WBM cuttings; spawning occurs throughout the 

year and, therefore the drilling operations cannot be timed to avoid spawning periods. 

Previous studies around single well sites in the North Sea have indicated that the area of 

seabed that would be covered with cuttings from the tophole section would be a circle of 

approximate radius of 5 m (BMT Cordah data). Although the Bardolino development lies 

within a large area in which Nephrops have been noted to spawn, the Bardolino site and 

pipeline route comprise sandy clay (Section 4.2.6), rather than the muddy sediments that 

Nephrops prefer. Consequently it is not thought likely that the Bardolino location is a 

significant Nephrops area. The area of seabed that could be affected by cuttings from the 

tophole sections at Bardolino is therefore likely to be very small in comparison to the area 

inhabited by or available to Nephrops. 

Mackerel, lemon sole and Norway pout are less susceptible to discharges of WBM and 

cuttings as they release their eggs into the water column, and have a widespread distribution 

over the North Sea (Section 4.4.3). The spawning populations of Nephrops, mackerel, lemon 

sole and Norway pout are not considered to be at risk from the top-hole discharges from the 

Bardolino well. 


It is not predicted that the initial discharge of WBM cuttings (Section 6.3.1) would result in the 

deposition of material in the Norwegian sector of the Continental Shelf, some 40 km away 

from Bardolino. 

The discharge of WBM and cuttings from the top-hole section of the well would cause a 

transient and localised smothering of the natural seabed sediments and associated benthic 

communities. Consequently, this would represent for a short time a very small additional 

cumulative impact on the quality of the benthic environment in this part of the central North 

Sea. This environment is impacted by a range of other activities, including other oil and gas 

operations and fishing (Section 4.5). The WBM and cuttings themselves would in time be 

dispersed and covered by natural sedimentation, allowing benthic communities similar to 

those that existed before drilling to be re-established at the sites. Within the 500 m safety 

exclusion zone around the well site these communities are likely to be afforded some 

protection from the effects of bottom-towed fishing gear. It is therefore suggested that over 

the lifetime of the project, the net cumulative effect of the drilling operations and presence of 

the well and pipeline on benthic ecology would be likely to be at least neutral. 

6.3.4 Consultee concerns 

No concerns were raised through the informal consultation process (Section 1.6). 

April 2008 Page 6-7


6.3.5 Adequacy of proposed mitigation measures 

The impact of the deposition of drill cuttings would be minimised by the use of WBM for the 

drilling of the top-hole sections of the well. The currents around the well location should also 

minimise impacts on the receiving environment by enhancing the dispersion and dilution of 

material. 

As far as is practicable, the WBM mud used would comprise chemicals that were PLONOR or 

of low HQ. All chemicals would be assessed as part of a chemical risk assessment prior to 

drilling, and this would provide an opportunity to consider alternative chemicals where the 

outcome of the risk assessment is unfavourable. The use and discharge of chemicals for the 

Bardolino well would be subject to a separate chemical risk assessment and would be 

submitted to BERR as part of the PON 15B application prior to drilling operations. The effects 

of the proposed drilling discharges at Bardolino are therefore not considered to be significant. 

The LTOBM-coated cuttings from the 17½”, 12¼”, 8½” and 6⅛” sections, would be returned 

to the drilling rig, where they would be contained, and then returned to shore for onshore reprocessing 

and disposal. Cuttings derived from any drilling using LTOBM would not be 

discharged to sea. 

Page 6-8 April 2008


6.4 ATMOSPHERIC EMISSIONS FROM THE BARDOLINO DEVELOPMENT 


Atmospheric emissions would arise as a result of the burning of diesel fuel during power 

generation and the flaring of production fluids during the following operations and activities 

associated with the Bardolino development: 

• the use of vessels to move the drilling rig; 

• the use of the drilling rig; 

• the use of vessels during drilling; 

• the use of vessels to install the subsea pipelines and umbilical; and 

• the well clean-up / testing of the well prior to production. 

The atmospheric emissions from the use of vessels can be estimated on the basis of the 

numbers of vessels, the duration of operations, the average daily consumption of fuel, and 

published conversion factors for the unit amounts of various gases emitted when fuel is burnt. 

Similarly, the emissions from flaring of production fluids can be estimated on the basis of the 

total masses of gas and oil burnt, and published factors for the combustion of those fluids. 

The main exhaust gases emitted by diesel-powered engines are carbon dioxide (CO2), 

together with small quantities of oxides of nitrogen (NOx), carbon monoxide (CO), oxides of 

sulphur (SO x) and trace quantities of volatile organic compounds (VOC), nitrous oxide (N 2O) 

and methane (CH4). The combustion products from flaring gas and oil are CO2, NOx, CO and 

VOCs. The main environmental effects of the emission of these gases to atmosphere are: 

• contribution to global warming (CO 2, CH 4); and 

• contribution to photochemical pollutant formation (NOx, SOx, VOCs). 

The direct effect of the cold emission of CH4 and VOCs is their implication in global climate 

change (CH 4 has 21 times the global warming potential of the main greenhouse gas CO 2) and 

contribution to regional-level air quality deterioration through low level ozone production. The 

indirect effects of these emissions are the effects of low level ozone, deleterious health 

effects, damage to vegetation, crops and ecosystems, and increase in greenhouse gases. 

The direct effect of NOx and VOC emissions is the formation of photochemical pollution in the 

presence of sunlight. Low level ozone is the main chemical pollutant formed, with byproducts 

that include nitric and sulphuric acid and nitrate particulates. The effects of acid 

formation include contribution to acid rain and dry deposition of particulates. The indirect 

effects of acid deposition are damage to buildings and vegetation, and a contribution to the 

acidification of soils and lakes. 

Drilling, pipeline and umbilical activities 

The operations to drill the development well and to install and tie-in the pipelines and 

umbilical would be completed within a relatively short period of time (3 months and 8 weeks 

respectively), and so the total gaseous emissions from these activities would not be 

significant. The estimated total amounts of combustion products from the drilling, installation 

and tie-in activities are given in Section 3.4.13 and summarised in Table 6.2. The small 

volumes of exhaust gases resulting from these activities would be rapidly dispersed in the 

offshore atmospheric environment. 

April 2008 Page 6-9


Table 6.2: Estimated atmospheric emissions from the combustion of diesel fuel during 

the drilling, pipeline and umbilical activities. 

Operation/Activity 

Estimated total air emissions during drilling, pipeline 

and umbilical installation 

Total 2005 emissions to air from UKCS offshore oil & gas 

installations 

% of total 2005 emissions to air from UKCS offshore oil 

& gas installations 

Emissions (tonnes) 

CO2 NOx SO2 

20,361.60 375.42 25.45 

18,333,624 59,778 2,936 

0.11% 0.63% 0.87% 

Source: Institute of Petroleum (2000); learnIT (2006); OSPAR Commission (2005) 

The contribution of approximately 20,362 tonnes of CO 2 resulting from power generation 

during the proposed drilling, pipeline and umbilical activities represents 0.11% of the total CO2 

emissions during 2005 from UKCS oil and gas installations. 

Well clean-up / testing operations 

The potential emissions from the well clean-up and testing of the Bardolino development well 

were estimated in Section 3.4.13. At the time of writing the final sequencing of well testing 

events has yet to be evaluated but no extended well testing is planned, and any clean-up and 

testing would be limited to 48 hours for each well. The potential emissions from well clean-up 

operations have been calculated based on a total testing and clean-up period of 48 hours with 

a maximum flow of 15,000 bbls (1,900 tonnes) of oil with an expected GOR of 870 scf/bbl 

(Table 6.3 and Table 6.4). This represents a worst case scenario for emissions. 

Table 6.3: Summary of the total estimated emissions from the clean-up of the 

Bardolino development well 

Emissions CO2 CO NOx N20 SO2 CH4 VOC 

Oil (tonnes) 6,413.50 36.08 7.42 0.16 0.03 50.11 50.11 

Gas (tonnes) 941.06 2.25 0.40 0.03 0.004 15.12 1.68 

Total (tonnes) 7,354.57 38.33 7.82 0.19 0.03 65.23 51.79 

Note: Conversion factors based on UKOOA well testing emission factors, assuming 95% flare efficiency: 

Oil 3.2 0.018 0.0037 0.000081 0.0000128 0.025 0.025 

Gas 2.8 0.0067 0.0012 0.000081 0.0000127 0.045 0.005 

Source: EEMS 2002 

The potential impacts of these emissions have been assessed in terms of their: 

• effects on air quality (by modelling of ambient NOx concentrations), in particular with 

relation to transboundary impacts (Section 6.4.3); and 

• contribution to regional / global effects such as acid rain, low level ozone formation 

and global climate change (Section 6.4.3). 

From a global perspective, these emissions represent a very small proportion of total 

emissions arising from all UKCS well testing and production activities, as illustrated in Table 

6.4. The emissions produced during the proposed well clean-up would not be expected to 

have any measurable impact on the creation of acid rain or on the existing input of 

greenhouse gases. The facilities are remote from land, and thus human populations will not 

be directly affected by the emissions. 



Table 6.4: Comparison of the total emissions from the Bardolino development well with 

emissions from UKCS well testing and UKCS offshore activities (All values are 

thousands of tonnes) 

CO2 CO NOx N20 SO2 CH4 VOC 

Total emissions from proposed clean-up 7.355 0.038 0.008 0.000 0.000 0.065 0.052 

Emissions from UKCS Well Testing 

Total emissions from UKCS well testing 1 120.909 0.502 0.10 0.003 0.001 1.401 0.612 

Emissions from proposed well cleanup 

(as % of UK total) 

Emissions from UKCS Offshore Exploration and Production Activities 

6.08 7.57 8 0 0 4.64 8.50 

Total emissions from UKCS offshore 

exploration and production 1 18,333.62 28.57 59.78 1.22 2.94 41.24 48.67 

Emissions from proposed well cleanup 

(as % of UK total) 

0.04 0.13 0.01 0 0 0.16 0.11 

Notes: 1. Total emissions for offshore activities includes emissions arising from; diesel, gas and fuel oil 

consumption, flaring, venting, direct process emissions, oil loading and fugitive emissions. This includes emissions 

from Production and Mobile drilling rigs. The SCOPEC data does not include emissions produced by support vessels 

or helicopters. Source: LearnIT, 2006 


There are no sensitive receptors or proposed or designated sites that would be impacted by 

these emissions. The contribution of these emissions to global processes such as global 

warming and acid deposition is discussed in Section 6.4.3. 

In the open conditions that prevail offshore, the atmospheric emissions generated during well 

clean-up and testing would be readily dispersed. This would ensure that, outside the 

immediate vicinity of the flare tip, all released gases would only be present in low 

concentrations. 


As Bardolino is located approximately 40 km from the UK/Norwegian median line, it is 

appropriate to consider the potential for trans-boundary transport of atmospheric 

contaminants. 

Wind conditions experienced offshore in the central North Sea are variable both in strength 

and direction, but it is likely that any air emissions at the Bardolino site will be quickly 

dispersed. Under these offshore conditions, the small amount of air emissions that would be 

produced is unlikely to be sufficient to have any measurable trans-boundary effect. The 

short-term, transient nature of the drilling and pipeline installation activities will minimise 

power generation emissions to air. The small volumes of resulting exhaust gases are 

expected to disperse rapidly in the offshore atmospheric environment. 

The potential cumulative effects associated with atmospheric emissions produced by the 

drilling operations, pipeline and umbilical activities and well clean-up / testing operations 

include global warming (greenhouse gases), acidification (acid rain) and local air pollution. 

The temporary increase in emissions from the proposed operations in relation to existing 

operations in the area will not result in a significant additive effect when considering the total 

annual offshore emission from the UKCS. Table 6.5 indicates that emissions of the identified 

pollutants would be equivalent to less than 1% of total annual offshore UKCS oil and gas 

atmospheric emissions compared with a 2004 baseline, the latest year for which published 

data are available. Table 6.5 also shows that the emission of gases, including carbon dioxide 

which contribute to global warming, represent a very small proportion (


Table 6.5: Estimated emissions from the Bardolino development 

Operation/Activity 

Maximum air emissions resulting from the well cleanup 

/ testing operations for Bardolino well 

Estimated total air emissions during drilling and 

pipeline activities 

Combined atmospheric emissions resulting from 

proposed Bardolino operations 

Total 2005 emissions to air from UKCS oil and gas 

installations 

Bardolino emissions as % of total 2005 emissions to 

air from UKCS offshore oil & gas installations 

Source: learnIT, 2006; 


Emissions (tonnes) 

CO2 NOx SO2 

7,354.57 7.82 0.03 

20,361.60 375.42 25.45 

27,716.17 383.24 25.48 

18,333,624 59,778 2,936 

0.15 0.64 0.87 



No extended well test / clean-up is planned; the operation would be limited to a total testing 

and clean-up period of 48 hours with a maximum flow of 15,000 bbls (1,900 tonnes) of oil with 

an expected GOR of 870 scf/bbl. 

Well clean-up procedures would be in place to ensure the operation was carried out as 

efficiently as possible. The flare burners to be used would be of high efficiency and operated 

to ensure they were working as efficiently as possible, in order to minimise emissions. There 

would be maintenance and monitoring of the burners by trained operators. The operators 

would be trained in how to adjust the air and water supply to the burners in order to minimise 

black smoke and oil drop-out. There would be monitoring of the wind direction in order to 

adjust the flare to optimum position, and monitoring of the sea state below the burner to allow 

a rapid response to the presence of any sheen. 

The contribution of these emissions to world-wide levels would be very low when compared to 

other sources, and emissions would be expected to disperse quickly upon release ensuring 

there was no local cumulative impact. 



6.5 LOCALISED DISTURBANCE TO THE SEABED FROM PIPELINE 

INSTALLATION, ROCK DUMP STABILISATION AND MATTRESSING 


The Bardolino well would be linked to the existing Howe subsea manifold through a new 2 

km, 6” oil export pipeline piggy-backed by a 3” gas lift pipeline, and a separate umbilical. The 

pipelay operations will be conducted by a DP vessel. The noise emanating from the thrusters 

of the DP vessel may disturb marine mammals in the area, and this effect is assessed in 

Section 6.7. 

At this stage it is planned that the umbilical will be laid in a separate trench from the 6” 

production pipeline and piggybacked 3” gas lift pipeline. The two trenches will be at least 30 

m apart (centre of trench to centre of trench). 

Trenching and backfilling the pipelines and the umbilical would disturb the benthos in the area 

along the proposed routes. Organisms on either side of both trenches would be buried by 

displaced material. There are currently two options to lay the piggy-backed pipelines; trench, 

backfill and spot rock dump the pipelines, or trench and blanket rock dump the pipelines. The 

top of the blanket rock dump would be below the level of the trench and the gap would be 

naturally infilled by surrounding sediments. Both options would require the creation of a ‘vee’shaped 

trench about 1.8 m deep that would be approximately 6 m wide at the top (Section 

3.5.3). Assuming that a 2 m wide strip on either side of the trenches would be affected by 

displaced soil from the trench, it is estimated that approximately 0.02 km 2 of seabed may be 

impacted by these trenching operations. 

A plough, jet or cutting tool may be used to create the trench for the umbilical. If a plough is 

used to create the umbilical trench, the trench will be left to infill naturally. If a jet or cutting 

tool is used to create the umbilical trench, the trench will backfill as the umbilical is laid. No 

rock dump would be required to stabilise the umbilical. 

Rock dumping the piggy-backed pipelines may be required for stabilisation and to prevent 

upheaval buckling. Blanket rock dumping the entire length of the piggy-backed pipeline will 

require an estimated 20,000 tonnes of rock dump, whereas spot rock dumping the pipeline 

would require a maximum of 10,000 tonnes of rock dump. 

Rock dumping would be achieved by the careful placement of graded crushed rock over the 

pipelines, using a dedicated rock dumping vessel. The vessel would be equipped with a 

dynamically positioned fall pipe, and the operation would be monitored by ROV to confirm the 

correct positioning of the rock (Section 3.5.3). 

Trenching and installation operations are expected to commence in June 2009 and last for 6 

weeks. Rock dumping the pipelines is scheduled to occur within this 6 week period. 

It is anticipated that a total of approximately 130 concrete mattresses would be required to 

stabilise the ends of the pipelines; 60 will be placed at the Bardolino manifold transition zone 

and 70 at the Howe manifold transition zone. The concrete mattresses would typically be 6 x 

3 x 0.15 m in size, with mattresses 6 x 3 x 0.3 m in size being used in areas where there is a 

high risk of damage from dropped objects. The total area of seabed that would be covered by 

the mattresses would be approximately 0.0023 km 2 . 

The total area of impact along the length of the proposed pipelines and umbilical would be a 

relatively small area when compared to the available habitat area. Access to other sea users 

along the length of the pipeline would be restricted for the period during installation, which 

would last 6 weeks. During this period, a dedicated guard vessel would ensure that 

fishermen were alerted to the presence of the pipeline. Installation of the proposed pipelines 

and umbilical may result in some interference with commercial fishing, shipping or military 



operations in the area. Restrictions for access to shipping and fishing will be limited to a 

safety radius 500 m centred on the vessel. 


In 2007, Shell commissioned an anchoring conditions survey centred on the Bardolino well 

location and encompassing the proposed Bardolino to Howe pipeline route. This survey 

obtained detailed information on the bathymetry and seabed conditions. 

Seabed sediments comprise a veneer of sand with outcrops of clay and scattered cobbles 

and small boulders (Gardline Geosurvey Limited, 2007). No regions of potential Annex I 

habitats or habitats of potential importance were identified during the survey. 

Once the trenching, backfilling and/or rock dumping have been completed, natural sediment 

redistribution and re-colonisation by benthic organisms would begin. This would occur as a 

result of organisms migrating from adjacent areas into the displaced sediments, the reestablishment 

of organisms that survived the displacement, and the settling out of eggs and 

larval stages from the water column. Given the dynamic nature of the seabed sediments in 

the area, the infauna would quickly re-colonise the physically disturbed area and re-establish 

a community similar to that in adjacent undisturbed areas. 

The completion of rock dumping over the pipeline, either blanket cover or spot rock dumping, 

would introduce a different substrate to the predominantly sandy clay substrate in this 

localised area, although the seabed at the Bardolino location has been found to contain 

occasional gravel (Gardline Geosurvey Limited, 2007). The blanket cover of the pipelines 

would be not extend above the level of the adjacent natural seabed and could be expected to 

be re-covered by surrounding sediments following rock dumping. The spot rock dumping will 

result in areas of gravel above the existing level of the seabed. These areas would be 

minimised as far as possible, and result in a change to only a very small area of substrate in 

comparison with the available existing habitat in the region surrounding Bardolino. The 

introduction of this material would not be expected to result in a significant change to the 

benthic communities in the area due to the localised nature of the spot rock dumping and the 

predominance of unperturbed natural habitat in areas adjacent to the pipeline. 

Fish species may move away from the immediate area during trenching and rock dumping, 

but it is anticipated that they would rapidly return to the area once pipeline installation 

operations have ceased. There could, however, be some very localised disturbance to 

species that spawn on the seabed. The proposed development area coincides with spawning 

areas for mackerel, lemon sole, Norway pout and Nephrops. 

Although the Bardolino development lies within a large area in which Nephrops have been 

noted to spawn, the Bardolino site and pipeline route comprise sandy clay (Section 4.2.6), 

rather than the muddy sediments that Nephrops prefer. Consequently it is not thought likely 

that the Bardolino location is a significant Nephrops area. However, the pipeline and 

umbilical installation are planned to commence in June 2009 and this would coincide with the 

peak spawning period for Nephrops (Section 4.4.3). Nephrops is widely distributed in the 

North Sea, however, and the area of seabed that would be affected by the installation of the 

pipelines would be very small in comparison to the area inhabited by the wider population. It 

is therefore anticipated that the operations to install the pipelines and umbilical would have no 

effect on the size or viability of Nephrops populations. 

Mackerel, lemon sole and Norway pout have a widespread distribution over the North Sea 

and release their eggs into the water column to be fertilised. The effects of installing the 

pipelines and umbilical are therefore not considered to be significant. 

Trenching, installation, backfilling and rock dumping operations would last approximately 6 

weeks, and during this time there would be restrictions on commercial shipping and fishing in 

the immediate area of the pipeline route. These are not considered to be significant as the 

restrictions would be short-term, fishing effort in the area (Section 4.5.1) is very low to low, 



and shipping activity in the area (Section 4.5.2) is moderate overall for this area of the central 

North Sea. 

Guard boats would be used to monitor vessel activity in the area during the pipeline 

operations. 

Once buried by rock dump or natural sediment infill, the physical presence of the pipelines 

and umbilical would pose no threat to bottom-towed fishing gear; the pipelines and umbilical 

would be trenched so that the top of the pipe is a minimum of 1.0 m below the natural seabed. 

Areas at either end of the pipelines that are not trenched, such as the tie-in spools, would be 

designed so as to prevent the snagging of fishing gear and shall be protected from dropped 

objects using concrete protection mats. In addition, the transition zones would lie within the 

statutory 500 m exclusion areas at Bardolino and the Howe subsea manifold. It is therefore 

concluded that the very local, temporary disturbance to the benthic community would be 

outweighed by the benefits gained by trenching, backfilling and/or rock dumping the pipelines 

to eliminate potential interactions with fishing gear. 

The location and profile of the spot rock dump material would be made available to fishermen 

and fishing interests. The blanket rock dump rock dump would be below the level of the 

trench. 

The tie-in spools and concrete mattresses protecting them would create new habitats for 

benthic organisms that live on hard surfaces. Such organisms typically include tubeworms, 

barnacles, hydroids, tunicates and bryozoans, which are commonly found on submerged 

rocky outcrops, boulders and offshore structures. These structures could also provide 

habitats for crevice-dwelling fish (e.g. ling) and crustaceans (e.g. squat lobsters and crabs). 

The overall disturbance would be negligible, as these structures will cover only a small area of 

the seabed. 


The installation of the pipelines and umbilical would cause localised temporary disturbance 

and interference along corridors of seabed estimated to cover a total area of approximately 

0.02 km 2 . The pipeline and umbilical installation operations would all be within UK waters, so 

there would be no transboundary impacts. Over the past decade, several pipelines have 

been installed in this area of the North Sea, but the installation of the proposed 2km long 

buried Bardolino pipelines and umbilical is unlikely to result in any cumulative impacts. 

The concrete mattresses that would be placed to protect the untrenched ends of the pipelines 

would be located within the 500 m safety exclusion zones, and would therefore not represent 

a cumulative impact on fishing. 

Spot rock dumping the pipelines would alter the character of a very small proportion of the 

seabed; sediment movement would begin to re-establish the natural seabed surface at these 

areas. 

There would be no global impacts. 


JNCC advised that survey data for the pipeline should ideally be presented within the ES. 

However, as the planned pipeline is only 2 km long, and 1 km of it will be within the 500m 

zones of Howe and Bardolino, JNCC suggested that, on this occasion, if the data were not 

available the ES should describe the survey work to be undertaken, with the complete results 

being included in the subsequent PON 15s. 


A 3 km by 3 km rig site survey was undertaken for the Bardolino well location, which 

encompasses the planned pipeline route corridor between Howe and Bardolino, to gain 

detailed information on bathymetry (Gardline Geosurvey Limited, 2007). No unusual seabed 



features were identified. A pipeline route corridor survey will be undertaken to gain more 

detailed information on seabed conditions, including soil samples and underwater 

photography, so that the optimum pipeline route and installation method can be selected 

(Section 4.2.6). The full results of this survey will be discussed within the future PON15C 

application to BERR to be submitted at least 28 days prior to installation operations are due to 

commence. 

Although benthic fauna would inevitably be physically impacted during the pipe-lay operation, 

the effects would be confined to a narrow corridor along the pipeline and umbilical routes with 

a total area of approximately 0.02 km 2 for both corridors, and the quality of the sediments 

would not be altered. The use of a DP vessel will avoid the potential impact of anchor scars. 

The use of a fall pipe on the rock dump vessel, and ROV supervision during rock dump 

operations, would ensure that the rock dump was placed in the correct position. Shell would 

obtain all necessary licenses before any rock dumping was carried out. 

The tie-in spools at Bardolino would be designed so as to prevent the snagging of fishing gear 

and will be protected from dropped objects using concrete mattresses. Their positions would 

be clearly marked on charts and notices to mariners. 

Shell will notify the Hydrographic Office, which will issue Notices to Mariners to advise fishing 

and shipping traffic of the potential hazards to navigation that would be associated with the 



given. Guard vessels would be on station during pipeline installation to alert shipping and 

fishing vessels of potential navigational hazards. 

The proposed mitigation measures are assessed to be sufficient to control the potential 

impacts of pipeline and umbilical trenching and installation operations. 



6.6 INSTALLATION AND PHYSICAL PRESENCE OF THE SUBSEA 

STRUCTURES 

6.6.1 Magnitude and Duration 

Shell propose to install a new production manifold and production tree at the Bardolino well 

location (Section 3.5.4) and a valve skid alongside the existing Howe production manifold. 

Installing these subsea structures would result in highly localised physical disturbance of the 

seabed sediments and associated fauna. It is likely that such impacts would be confined to 

the area of seabed over which the subsea structures have been installed. 

The new production manifold would be transported to the Bardolino location by a DP vessel 

and deployed to its seabed location in a single lift (Section 3.5.4). The manifold would be 

approximately 9 x 6 x 4 m in size and would be secured to the seabed by 4 piles, one at each 

corner. The total area of seabed that would be covered by the manifold would be 

approximately 54 m 2 . 

The production tree would have a footprint of approximately 24 m 2 . . 

A valve skid would be deployed to the seabed by the drilling rig and would be fixed by piles 

alongside the existing Howe manifold. The valve skid would be approximately 4 x 5.5 x 3.5 m 

in size, and would cover 22 m 2 of seabed. 

Installation operations are scheduled to occur in August 2009. 

The physical presence of these new subsea structures may result in some interference with 

commercial fishing or shipping operations in the area. 

6.6.2 Impact on Sensitive Receptors 

Installing the production manifold, tree and valve skid would result in localised physical 

disturbance of the seabed sediments and associated fauna. This would result in loss of 

habitat in the area directly below the subsea structures, with consequent impact on the 

benthic invertebrate community. Given the small sizes of the installations, however, the total 

area of seabed that would be covered by them or possibly perturbed during their installation, 

would be very small and the disturbance highly localised. 

The subsea structures are located in an area of low commercial value for all fish species 

caught by UK fishermen in comparison to all areas fished around the UK. The main fishing 

gears used in the area are demersal / bottom trawling methods (Section 4.5.1) which have 

the greatest potential to interact with subsea structures. 

The production manifold, tree and valve skid would be located within protective tubular steel 

frames which have a fishing-friendly profile with sloping sides designed to withstand fishing 

interaction loads and dropped object loads. No significant operational problems for demersal 

trawling are foreseen from the presence on the seabed of these structures and their 

protective covers. 

The impacts from noise associated with the piling and vessel operations during installation 

are discussed further in Section 6.7. 


The proposed pipeline, crossings and subsea structures lie entirely within UK waters 

therefore there will be no transboundary impacts from the installation and physical presence 

of the structures. 






Although benthic fauna would inevitably be physically impacted by the installation and 

presence of the production manifold, production tree and valve skid, the effects would be 

confined to three very small areas of seabed totalling some 100 m 2 . This represents a tiny 

fraction of the available seabed in the Blocks covering the Bardolino development. Except for 

the very small areas beneath them, the quality of the sediments would not be altered by the 

installation of the structures. The use of a DP vessel to deploy the manifold will avoid the 

potential impact of anchor scars. 

A post-lay survey of the seabed will be conducted by Shell to verify that the structures are 

installed according to plan, and are over-trawlable. 

The subsea structures and their protective structures would be designed to ensure that they 

do not impede fishing activities and would withstand fishing interaction loads and dropped 

object loads. 

Shell will notify the Hydrographic Office, which will issue Notices to Mariners to advise fishing 

and shipping traffic of the potential hazards to navigation that would be associated with the 



given. Guard vessels would be on station during installation to alert shipping and fishing 

vessels of potential navigational hazards. 



6.7 NOISE ARISING FROM THE BARDOLINO DEVELOPMENT ACTIVITIES 


In general terms, sound can be characterised with reference to two features, the frequency at 

which it is emitted (measured in hertz (Hz)) and the strength or intensity of the sound 

(measured in decibels (dB)). Noise from various sources may combine or cancel to produce 

a pattern of noise in the marine environment that is characterised by variations in frequency 

and noise level. Noise levels in the marine environment are attenuated by distance 

(dispersion in 3 dimensions), and by absorption by the water. The degree of absorption is 

roughly in proportion to the square of the frequency. 

The main sources of sound associated with the proposed project are: 

• a semi-submersible drilling rig; 

• a standby vessel; 

• 3 anchor handling tug vessels (AHTVs); 

• a guard vessel; 

• a DP pipelay vessel (which utilises thrusters to maintain its position); 

• a trenching / backfill vessel; 

• a rock dump vessel; 

• a survey / umbilical vessel; 

• a dive support vessel (DSV) to tie-in and commission pipeline; and, 

• piling the subsea structures. 

The characteristics of the noises produced by different types of vessels and activities are 

shown in Table 6.6. 

Table 6.6: Examples of underwater noise levels produced by different types of vessel 

or different types of activity 

Source Source levels of underwater noise 

(dB re 1µPa at 1m)* (predominant frequency if known) 

Drilling from semi-submersible 154 (100 to 500Hz) 

Tug / Barge 140 to 170 

Trenching 159 to 174 (500 Hz) 

Supply / Support Vessel 170 to 180 (500Hz) 

DP pipelaying vessel 177 (500-1,000Hz) 

Pile driver 206 

Helicopters (various) & at various altitudes 101 to 109** 

Key: dB re1µPa at 1m – unit of Sound Pressure Levels measured at a 1m range from source 

* Most data taken from 1/3-octave band centre frequencies (50-2000Hz) 

** Measured at the water surface 

Source: Richardson et al., 1995; Evans and Nice, 1996. 

The noise resulting from normal operations of the drilling rig and associated vessels, including 

the DP vessel, would be steady and continuous, and sudden changes in the frequency or 

levels of noise would be unlikely. Marine mammals are the most sensitive receptor for 

underwater noise from offshore operations. Animals moving into or through the area may 

experience a growing level of noise as they approach the development and pipelaying 

operations. Marine mammals would therefore have time to react to this noise and move away 

from the source of disturbance. Given the relatively low density of marine mammals in the 

area, and the ability of the mammals to move away from sources of noise, it is unlikely that 



the noise resulting from the pipeline installation would have any measurable or long-term 

effect on marine mammals frequenting the area. 

Inspection of the data in Table 6.6, and assessment of the range of noise sources, and their 

magnitude and duration, indicates that the noise from piling would be the most significant 

potential source of underwater noise affecting marine mammals. Consequently the rest of 

this section examines this noise and its potential effects in greater detail. 

6.7.2 Noise produced development activities 

Noise generated during piling operations 

Piling operations create underwater noises of a frequency and level that are audible to seals, 

toothed and baleen whales, and fish (Richardson et al., 1995; Nedwell & Howell, 2004; 

Nedwell et al., 2004). Noise from piling can enter the marine environment by four pathways, 

the most significant of which is thought to be by transmission of vibration through the pile itself 

directly into the water column. The noise produced during piling is dependent on the several 

factors including the type of equipment used, the size of the pile, the water depth and the 

characteristics of the seabed (Nedwell et al., 2004). 

The production manifold would be secured to the seabed by means of four piles. Each pile 

would be 610 mm in diameter and 20 m long, and would be driven to the required depth in the 

seabed by an underwater vibro-hammer. It would take about 12 hours to install the four 

manifold piles. 

The valve skid would be secured to the seabed by means of four piles, and these would be of 

smaller diameter and length than those used to install the production manifold. Again, each 

pile would be installed separately using a vibro-hammer, and it would take about 12 hours to 

drive the 4 valve skid piles. 

There are no specific measurements available for the noise levels that would be produced 

during operations to fix such piles in a sandy clayey seabed in a water depth of approximately 

85 m. From noise measurements of other piling operations taken under different 

circumstances, however, there appears to be a correlation between the diameter of the pile 

being driven and the Source Noise Level (SL) (Nedwell et al., 2005). The best fit line shows; 

SL = 24.3D +179 dB re 1µPa @ 1 m 

where D is pile diameter in metres. Application of this equation would suggest that the source 

noise level for a 0.61 m (610 mm) diameter pile might be approximately 194 dB re 1µPa @ 1 

m. The frequency profile for piling noise is rather “flat” with no obvious peak, but maximum 

pressure levels are attained over the range 300 - 1,000 Hz (Nedwell et al., 2005). The larger 

piles used to secure the production manifold will produce a higher source level than those 

required to secure the valve skid, so modelling has been undertaken for the production 

manifold piling as this represents the worst case event. 

Acoustic propagation modelling was conducted for the production manifold pile driving at the 

Bardolino field, using accepted formulae, to calculate the noise propagation in the marine 

environment. This was combined with audiograms for marine mammals to predict the 

distances at which strong avoidance and a Temporary Threshold Shift (TTS) would occur in 

the species which are most likely to be exposed to the noise from piling. The technique 

employed reflects the current state of knowledge regarding underwater noise and its impact 

on marine species. 

During piling the noisiest vessel that is likely to be under way and in close proximity to the 

piling operations would be a DP vessel. The decibel scale used to measure sound is a 

logarithmic scale, therefore the presence of several sources of noise at any location at any 

one time leads to only a small increase in the total source level of noise at the site. The 

estimated noise level from this DP vessel operating at the site would be 180 dB re 1µPa dB 

@ 1 m. The difference between the source level noise for piling (194 dB) and source level 

noise for the vessel (180 dB) is more than 10 dB, so the presence of this additional noise 



source would make no significant contribution to the total source noise level at the site during 

the piling operations (Norton, 1989). 

Noise generated during pipeline installation operations 

The underwater noise that is produced by vessels arises from two sources – propeller 

cavitation and the propulsion machinery inside the vessel. Vessel noise may be considered 

to be a continuous, rather than transient noise source, which is a combination of broadband 

noise and tonal sounds at specific frequencies (Richardson et al., 1995). 

The noise that would be generated by the vessels would be determined by the types and 

numbers of vessels that are present at the site at any one time. Because the decibel scale 

used to measure sound is a logarithmic scale, the presence of several sources of noise at any 

location at any one time leads to only a small increase in the total source level of noise at the 

site. 

Published data on the sound source levels and frequencies for different types of vessels are 

provided in Table 6.6. Sound levels and frequency characteristics are depended on ship size 

and speed, with variations among vessels of similar classes (Richardson et al., 1995). Noise 

from shipping is roughly related to vessel size; larger ships have larger, slower rotating 

propellers, which produce louder, lower frequency sounds. Broadband source levels of ships 

between 55 and 85 m are generally around 170-180 dB re 1 µPa @ 1 m (Richardson et al., 

1995), with most energy below 1 kHz. The use of bow thrusters can increase broadband 

sound levels by 11 dB and includes higher frequency tonal components up to 1 kHz 

(Richardson et al., 1995). 

There are currently two pipeline options which would require the operation of a number of 

different vessel types in the Bardolino area over a total period of 6 weeks. All would be 

typical of the vessels routinely used in the UK North Sea for oil and gas operations and other 

activities. 

• A dynamically positioned (DP) reel lay vessel would be used to lay the piggy-backed 

pipelines simultaneously onto the seabed. 

• Trenching would be carried out using a seabed plough towed by an anchor handling 

tug vessel (AHTV). 

• Rock dumping would be achieved by the careful placement of graded crushed rock 

over the pipelines, using a dedicated rock dumping vessel. 

• A DP dive support vessel (DSV) would be in the field for several different phases, 

such as tie-in spools and hydro-testing. 

• Guard vessels would be on site throughout the pipeline operations. 

• A DP survey vessel would be used to ensure that the pipes were laid in the correct 

location and that trenching activities were performed satisfactorily. 

The noise produced by subsea trenching operations depends on the equipment used and the 

nature of the seabed sediments. A trenching noise spectrum reported in Richardson et al. 

(1995) has peak levels of 178 dB re 1µPa @ 1 m at 160 Hz, with an overall source level 185 

dB re 1µPa @ 1 m; this is similar to the data reported by Nedwell et al. (2004). These levels 

are for mechanical dredging operations, and may be noisier than the proposed pipeline 

installation operations for the Bardolino development which would use a towed plough. 

During the pipeline installation operations the vessels that are likely to be present in the area 

include DP pipelay vessel (180 db), AHTV for trenching (170 dB), dive support vessel (180 

dB), guard vessel (180 dB), survey vessel (180 dB) and rock dump vessel (180 dB) (Table 

6.6). The estimated noise level from this combination of vessels operating simultaneously at 



the site would be 187 dB re 1µPa dB @ 1 m. The estimated total noise during the pipeline 

installation operations, including the potential noise from the trenching operations, would be 

189 re 1µPa dB @ 1 m, which is lower than the estimated noise levels during the piling 

operations (194 dB) which have been modeled. 

Applying the equation provided by Richardson et al. (1995): 

[Lr = Ls – 15.log(range km) - 5.log(depth m) - 60 (dB re 1mPa)] 

the predicted source noise levels for the pipeline installation and vessel activities gives 

estimates of the received noise levels with increasing distance from source (Table 6.7), and 

the estimated distance to a received level of 120 dB is 0.9 km. For many marine mammals, 

disturbance occurs at broadband received noise levels of about 120 dB re 1µPa for 

continuous noise (Erbe and Farmer, 2000). 

Table 6.7: The predicted received noise level at distance from the source noise level 

during pipeline installation operations at the Bardolino location 

Range (km) 1 2 5 10 20 50 100 

Received Level 

(dB) 

119.6 115.0 109.1 104.6 100.0 94.1 89.6 

Note: Water depth is 85 m 

Source level of 189 dB without absorption 

Noise produced during drilling operations 

The Bardolino development well would be drilled from a semi-submersible drilling rig. The 

drilling rig would be towed to the Bardolino location by three AHTVs, with a stand-by and a 

guard vessel in attendance. Drilling operations are scheduled to last for 3 months (Section 

3.3.2). 

The estimated underwater noise level during drilling operations would be 184 dB re 1µPa dB 

@ 1 m, based on the presence and operation of a semi-submersible drilling rig (127 dB), 

standby vessel (180 dB), three AHTVs (3 x 170 dB) and guard vessel (180 dB) (Table 6.6). 

The estimated noise levels during the drilling operations are lower than the estimated noise 

levels during the piling operations which have been modeled. 

Applying the equation provided by Richardson et al. (1995): 

[Lr = Ls – 15.log(range km) - 5.log(depth m) - 60 (dB re 1mPa)] 

the predicted source noise levels for the drilling and vessel activities gives estimates of the 

received noise levels with increasing distance from source (Table 6.8), and the estimated 

distance to a received level of 120 dB is 0.4 km. 

Table 6.8: The predicted received noise level at distance from the source noise level 

during drilling operations at the Bardolino location 

Range (km) 1 2 5 10 20 50 100 

Received Level 

(dB) 

114.0 109.4 103.5 99.0 94.4 88.5 84.0 

Note: Water depth is 85 m 

Source level of 184 dB without absorption 

6.7.3 Impact on sensitive receptors or designated sites 

Sound is important for marine mammals and serves three main functions: 

(i) it provides information about their environment; 

(ii) it is used for communication; and 



(iii) it enables the remote detection of prey. Therefore excessive underwater noise 

has the potential to cause disturbance through interference with communication, 

navigation and foraging. 

The effects of underwater noise on marine mammals may vary depending on the received 

noise level, and there are several different levels of response quoted in the literature (e.g. 

David, 2006; Masden et al., 2006; Richardson et al., 1995): 

• Detection level (zone of audibility) – the noise level that the species would normally 

be able to detect in a quiet sea state. The zone of audibility is defined as ‘the range 

at which an animal can barely detect the sound source’ (Masden et al., 2006). 

• Avoidance level (zone of responsiveness) – the noise level at which the species 

would start to exhibit active avoidance behaviour, such as moving away. The zone of 

responsiveness is defined as ‘the zone in which the animal responds to the sound 

exposure either behaviourally or physiologically’ (Masden et al., 2006). 

It is proposed that levels of 90 dBht(species) and above would cause significant 

avoidance reaction, with strong avoidance by most individuals at 100 dB ht(species). 

Mild avoidance reaction occurs in a minority of individuals at levels above about 75 

dBht(species) (dBht is a measure of the level of sound above the animals hearing 

threshold, or its “perception level”) (Nedwell et al., 2004). 

• Masking level (zone of masking) – the noise level that could mask the species 

vocalisation (communication and echolocation signals). The zone of masking is 

defined as ‘the range at which the anthropogenic noise adds significant energy to the 

ambient noise in frequency bands that overlap with the signals of interest’ (Masden et 

al., 2006). Masking is predicted when noise levels are above the received 

vocalisation level and hearing threshold. 

• Temporary threshold shift (TTS) threshold – the noise level that would cause a 

temporary but reversible shift (change in hearing ability) in the individual’s hearing 

sensitivity. 

When an animal is exposed to a loud noise for a period of time, the acuteness of its 

hearing may be temporarily diminished, i.e. it may be unable to detect noise levels 

that it would normally be expected to hear. This phenomenon is reversible (or 

disappears) some time after the animal is removed from the loud noise source. In a 

review of threshold levels, Ketten (1998) concluded that a noise level of 140 dB, that 

is also 80 – 90 dB above the species hearing threshold at each frequency, is 

necessary to produce a significant temporary change in hearing ability. 

• Permanent threshold shift (PTS) – the noise level that would cause a permanent shift 

in the individual’s hearing sensitivity. 

• Physical damage level – the noise level or pressure level that would result in gross 

physical damage to the organism’s auditory system, other organs or tissues. 

The threshold peak impulse sound pressure for direct physical trauma in marine 

mammals is generally considered to be >200 dB (McCauley, 1994; Richardson et al., 

1995; Gordon et al., 2004). 

Underwater noise may result in the exclusion of cetaceans from important habitats or impede 

reproductive and feeding patterns (Richardson et al., 1995). In addition, underwater noise 

also has the potential to disturb prey species. The potential effects of changes in prey 

availability or access to foraging areas on marine mammals is largely unknown. Most marine 

mammal species may be able to change their diet and feeding areas in response to shortterm 

changes in prey availability. However, long-term changes have the potential to affect 

their distribution, body condition, susceptibility to disease, exposure to contaminants, 

reproductive success, and survival. 



Underwater noise can have a severe effect in the immediate vicinity of high level pressure 

sources, such as that caused by piling. At greater distances from the source, the noise would 

decrease and its effects would diminish (Nedwell et al., 2004, 2005). 

Pile-driving generates signals of a very high source level and broad bandwidth (Richardson et 

al., 1995). Piling operations create underwater noises of a frequency and level that are 

audible to seals (pinnipeds), toothed whales, dolphins and porpoises (odontocetes) and 

baleen whales (mysticetes) (Richardson et al., 1995; Nedwell and Howell, 2004; Nedwell et 

al., 2004). Noise from piling can enter the marine environment by four pathways, the most 

significant of which is thought to be by transmission of vibration through the pile itself directly 

into the water column. The noise produced during piling is dependent on the several factors 

including the type of equipment used, the size of the pile, the water depth and the 

characteristics of the seabed (Nedwell et al., 2004). The potential impact of piling noise on 

sensitive receptors depends on the actual level of noise received by the receptor at a certain 

distance from the source, and the animal’s sensitivity and response to that noise. 

The minimum level of noise that each species of marine mammal is able to detect (the 

hearing threshold) varies with the frequency of the noise. Audiograms illustrate the range of 

frequencies that a species is able to detect, and the frequency range over which the species’ 

hearing is most acute. For an underwater noise to have an effect on an animal it must have a 

frequency spectrum that is detectable by the particular species, and loud enough to be 

audible. Audiograms have been obtained for four of the species of marine mammal which are 

known to be present in the area of the Bardolino development, namely harbour porpoise, 

bottlenose dolphin, killer whale and minke whale. Table 6.9 shows the hearing ranges and 

peak frequencies for these species. 

Table 6.9: Hearing characteristics of some species or groups of marine mammals 

likely to be present at the Bardolino location 

Species Hearing range (Hz) 

Approximate peak 

frequency (Hz) 

Harbour porpoise 200-200,000 100,000-200,000 30-60 

Bottlenose dolphin 100-300,000 50,000-80,000 40-50 

Killer whale 500-200,000 10,000-30,000 30-45 

Minke whale 10-10,000 300-400 30-40 

Source: Nedwell et al. (2004), Richardson et al. (1995) 

Noise modelling 

Threshold at peak frequency 

(dB re 1µPa) 

Propagation of sound can be modelled to predict the sound level at any distance from the 

noise source. A common method is the Source Level – Transmission Loss model (Nedwell 

and Howell, 2004). The Source Level refers to the level of sound measured at one metre 

from the noise source, expressed in dB re 1 µPa @ 1m. As an acoustic signal travels through 

the ocean, it becomes distorted due to multi-path effects and weak due to various loss 

mechanisms (Jensen et al., 1994). The standard measure of the change in signal strength in 

underwater acoustics is called Transmission Loss. It is calculated as the sum of a loss due to 

geometrical spreading and a loss due to attenuation. Spreading Loss is a measure of the 

signal weakening as it propagates outward from a source. 

There are two main geometrical spreading laws to be considered in underwater acoustic 

modelling (see Jensen et al., 1994; Richardson et al., 1995), namely spherical spreading and 

cylindrical spreading. Spherical spreading is characterised by multi-directional propagation 

with loss of energy that is inversely proportional to the square of the distance from the source, 

whereas cylindrical spreading, which is typical of noise propagation in shallow waters, has a 

loss of energy inversely proportional to the distance from the source. For “shallow waters” 

(i.e. water depths of less than 200m), the cylindrical model should be applied (Jensen et al., 

1994). 

The following equation was used to model noise propagation: 



SPL(r) = SPL(source) –N log(r) 

SPL=SL-TL 

where SPL is Sound Pressure Level, r is distance from the source, N is the transmission loss 

coefficient, SL is the source level and TL is the transmission loss (both measured in dB). 

The model scenario was based on a sound level at source of 194 dB @ 1m at a frequency at 

source selected as the frequency at which the species shows most sensitivity within the range 

of 300-1000 Hz, and a single noise source was considered (Nedwell et al., 2005). The 

transmission loss coefficient was assumed to have a value of 22 (reflecting depth of water). 

Absorption loss coefficient was calculated using the formula from Erbe & Farmer (2000): 

α = 

2 

2 

−3 

0. 

11 f 44 f 

−4 

2 

3. 3× 

10 + + + 3. 

0 × 10 f 

2 

2 

1+ 

f 

4100 + f 

The scenario details for the model runs are provided in Table 6.10. 

Table 6.10: Scenario details for the model runs to assess the potential impacts during 

piling operations at the Bardolino location 

Scenario Species 

Sound level 

at source 

(dB at 1m) 

Frequency at 

which 

species 

shows most 

sensitivity 

(Hz) 

Threshold value 

for species 

derived from 

audiogram (dB) 

Predicted level at 

which TTS may 

occur (dBht) 

1 Harbour porpoise 194 1,000 80 140 

2 

Bottlenose 

dolphin 

194 700 

91 

140 

3 Killer whale 194 500 100 140 

4 Minke whale 194 400 34 124 

Source: Nedwell et al., 2005 

Thresholds for response to noise: 

For the purposes of assessing the potential effects of the proposed Bardolino development on 

marine mammals, the EIA focused on determining which activities might produce noises loud 

enough to result either in an animal displaying a “strong avoidance reaction”, or to cause a 

temporary change in hearing ability (a “temporary threshold shift (TTS)). The threshold for 

“strong avoidance” was selected because it is the lowest level at which overt behavioural 

changes occur. The TTS level was selected because it is the least damaging of the possible 

physical effects and would be found over the largest area in which physical effects might 

occur. It is therefore the most precautionary physical threshold. 

Noise modelling results 

Figures 6.1 to 6.4 show the results of the modelling which demonstrate the variation in 

perceived sound level with distance from the noise source for the four marine mammals 

studied (BMT Cordah, 2008a). 



Figure 6.1: Variation in perceived sound level with distance from source for Harbour 

porpoise 

Figure 6.2: Variation in perceived sound level with distance from source for Bottlenose 

dolphin 



Figure 6.3: Variation in perceived sound level with distance from source for Killer 

whale 

Figure 6.4: Variation in perceived sound level with distance from source for Minke 

whale; the red circle at 1 km indicates the marine mammal observer (MMO) exclusion 

zone. 

Figure 6.4 indicates that the region of 1 km radius observable by a Marine Mammal 

Observer, known as the exclusion zone, will cover the majority of the area theoretically 

calculated by the model as a region where strong avoidance behaviour by Minke whale might 



be observed due to noise from piling. Given the planned mitigation measures to be 

undertaken by Shell (Section 6.7.6), including the use of an MMO and in particular the “soft 

start” procedure agreed with JNCC, is likely that any Minke whale in the area will move away 

before noise levels reach a level which would cause significant disturbance. 

Table 6.11 summarises the maximum radii for zones of avoidance and temporary change in 

hearing ability (TTS) for the four species studied during piling at the Bardolino location. 

Table 6.11: Estimated maximum radius for zones of strong avoidance reaction, and 

temporary change in hearing ability, for selected species exposed to a 194 dB source 

noise from piling operations at the Bardolino location 

Species 

Avoidance reaction 

Estimate maximum radius (km) 

Temporary change in hearing 

ability 

Harbour porpoise < 0.02 0 

Bottlenose dolphin < 0.01 0 

Killer whale < 0.01 0 

Minke whale 1.5 0.05 

The results of noise modelling to asses the impact of piling using frequencies at which each 

species shows most sensitivity within the range of 300-1000 Hz, using a maximum noise level 

of 194 dB at the Bardolino site, indicate: 

• Harbour porpoise, bottlenose dolphin and killer whale would not experience TTS due 

to piling operations. 

• Minke whale may experience TTS due to piling operations up to 50 m from the noise 

source. 

• For harbour porpoise, the region of strong avoidance extended to 10 m from the noise 

source. 

• For bottlenose dolphins, the region of strong avoidance extended to 10 m from the 

noise source. 

• For killer whale, the region of strong avoidance extended to 30 m from the noise 

source. 

• For Minke whale the region of strong avoidance extended to 1.5 km from the noise 

source. 

These results are presented in Figure 6.5. 



Figure 6.5: Potential regions of strong avoidance (SA) and temporary threshold shift 

(TTS) due to piling noise at Bardolino (distance on axes in km) 

0 

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 

-0.5 

-1 

-1.5 

Potential effects of noise during piling operations 

2 

1.5 

1 

0.5 

-2 

SA Minke Whale 

TTS Minke Whale 

TTS Bottlenose Dolphin and 

Killer Whale 

TTS Harbour Porpoise 

1km distance 

The proposed piling operations to install the Bardolino subsea structures are scheduled to 

take place during June / July 2009 and are anticipated to take 2 weeks. Harbour porpoises 

have been sighted in Quadrant 22 and surrounding quadrants in June and July. Bottlenose 

dolphins have not been recorded within Quadrant 22 or surrounding quadrants during May 

and June, although white-beaked and white-sided dolphins have been recorded in June and 

July. Minke whales have been recorded within Quadrant 22 during July and in surrounding 

quadrants in June. Killer whales have been recorded in surrounding quadrants in October, 

which is outside the current proposed piling period (Section 4.4.4). 

Given the very short duration of piling operations, the very limited area of sea over which any 

species might experience noise levels that would result in a strong avoidance reaction, and 

the mitigation measures that would be in place (Section 6.7.6), it is considered unlikely that 

any individual of the studied species would be exposed to a noise level that caused significant 

effects. The noise modelling indicates that piling operations could result in a TTS in Minke 

whales within a radius of 50 m of the noise source. The proposed mitigation measures 

should, however, ensure that any individual would move at least this distance from the vicinity 

of the noise source before the source reached a level which could cause a TTS effect. 



Potential effects of noise from drilling operations 

There are few published data on underwater noise levels near drilling rigs and on the 

responses of marine mammals near those facilities, but underwater noise levels may often be 

low, steady and not very disturbing (Richardson et al., 1995). Available data suggest that 

noises produced by drilling are not very intense, and are strongest at very low frequencies. 

The distance over which marine mammals would detect and react to the noise associated 

with the drilling operations at the Bardolino location are relatively small; the estimated 

distance to a received level of 120 dB is 0.4 km (Table 6.8). 

Drilling activities are likely to have little effect on the marine mammals as the perceived noise 

levels are only likely to cause avoidance reactions over very small distances from the noise 

source. The source noise level is below the threshold value for avoidance reaction and TTS. 

As noise associated with the drilling activities would be very localised, and given the large 

area of habitat available, it would not be considered to have a significant impact on the marine 

mammals. 

Potential effects of noise from pipeline installation and vessels 

The noise resulting from normal operations of the DP pipelay vessel would be steady and 

continuous, and sudden changes in the frequency or levels of noise would be unlikely. 

Animals moving into or through the area may experience a growing level of noise as they 

approach the development and pipelaying operations. Marine mammals would have time to 

react to this noise and move away from the source of disturbance. 

The pipelay operations are planned to begin in June 2009 and be completed within 6 weeks. 

Harbour porpoises have been sighted in Quadrant 22 and surrounding quadrants in June and 

July. Bottlenose dolphins have not been recorded within Quadrant 22 or surrounding 

quadrants during May and June, although white-beaked and white sided dolphins have been 

recorded in June and July. Minke whales have been recorded within Quadrant 22 during July 

and in surrounding quadrants in June. Killer whales have been recorded in surrounding 

quadrants in October, which is outside the current proposed piling period (Section 4.4.4) 

The distances over which marine mammals would detect and react to the noise associated 

with the pipeline operations and vessels at the Bardolino location are relatively small; the 

estimated distance to a received level of 120 dB is 0.9 km (Tables 8.3). Given the ability of 

the mammals to move away from sources of noise, it is unlikely that the noise resulting from 

the pipeline installation and vessels would have any measurable or long-term effect on marine 

mammals frequenting the area. 

Evidence suggests that marine mammals disturbed temporarily by noise associated with 

offshore oil and gas development operations, such as piling, pipeline installation, drilling and 

vessels, would move back into the area once the noise ceased (Tougaard et al., 2003). 


Modelling the noise from piling operations suggests that noise levels likely to result in a strong 

avoidance reaction in harbour porpoise, bottlenose dolphin and killer whale would extend to 

distances of approximately 20 m, 10 m, and 10 m respectively, from the piling site and up to 

1.5 km for Minke whales. It is therefore unlikely that dolphins, porpoises or Minke whales in 

the Norwegian sector would be exposed to noise levels that would result in any significant 

impacts. 

Given the short duration of the proposed piling operations (approximately 24 hours in total), 

and the limited size of the area over which avoidance reactions may be elicited in the species 

under consideration, it is anticipated that there would be no cumulative effects from piling 

noise. 



It is likely that the noise effects of the vessels associated with the proposed activities would 

be similar in character to normal commercial shipping activities. Consequently, cumulative or 

global impacts would be unlikely. 


During the informal consultation process (Section 1.6), JNCC advised that within the ES, 

Shell should consider whether any of the proposed activities are likely to cause 'deliberate 

disturbance’ to a European Protected Species (EPS). JNCC advised that whilst Shell needed 

to carry out the assessment, the use of mitigation measures (including the use of a Marine 

Mammal Observer (MMO), the restriction of piling activities to daylight hours, and those other 

measures included within the Shell agreed procedure for offshore piling activities), are likely 

to be sufficient mitigation measures to ensure that the proposed activities do not cause 

disturbance to any EPS. 


Noise during the Bardolino development activities would be generated underwater primarily 

by piling activities during the installation of the manifold, production tree and valve skid. The 

duration of the main piling activities will be around 24 hours in total, over two periods of 

activity. Modelling has shown that various species of marine mammals within 10 m to 1.5 km 

of the site could experience received noise levels that might cause a strong avoidance 

reaction (Table 6.11); that is, the animals would move away from the source of noise. 

Evidence suggests, however, that marine mammals disturbed temporarily in this way would 

readily move back into the area once the noise ceased. 

The area in which marine mammals might be exposed to received noise levels that might 

elicit a strong avoidance reaction is very small in comparison with the area of the central 

North Sea. The densities of marine mammals in this area are low, and the proposed period 

for piling does not coincide with any peaks of marine mammal abundance (Section 4.4.4). It 

is therefore expected that the overall potential impact of piling operations, even without the 

mitigation measures described below, would not be significant. 

Modelling has also shown that the area within which received noise levels may be loud 

enough to cause a TTS would extend to approximately 50 m for a Minke whale, and that 

piling noise would not be expected to result in a TTS for harbour porpoise, bottlenose dolphin 

or killer whale (Table 6.11). The mitigation measures that the project would employ would be 

designed to ensure as far as possible that piling did not begin while marine mammals were 

within this zone, that marine mammals were gradually exposed to increasing levels of noise 

so that they could move away from the source of noise, and finally that piling would be halted 

if marine mammals were observed within a pre-defined zone around the site. 

The JNCC has developed guidelines for use during seismic survey operations, and these can 

be modified and applied to piling operations in order to reduce the likelihood that marine 

mammals would be exposed to significantly elevated noise levels. Shell has developed a set 

of guidelines in line with the JNCC guidelines, to be used for all offshore piling operations 

within the UKCS (Shell, July 2007). These procedures are included in Appendix 4. These 

Guidelines for Minimising Acoustic Disturbance to Marine Mammals from Piling Operations 

have been discussed and agreed with JNCC, and will be followed during the piling operations 

at Bardolino. Important mitigation features from these guidelines, that would be incorporated 

into the Bardolino piling operations, are: 

• Piling would only begin during daylight hours. 

• A qualified and experienced marine mammal observer (MMO), whose suitability has 

been agreed with the JNCC prior to the operation, would be present on the standby 

vessel throughout the operations, to monitor the presence of marine mammals in the 

area. 



• Piling would only begin when it was confirmed that marine mammals had not been 

observed within a 1km radius of the piling operation for 30 minutes before the 

commencement of piling. 

• A “soft start” would be undertaken for each new period of piling, in which the piling 

force (and thus the resulting noise level) was gradually increased, so as to alert marine 

mammals in the area and give them the opportunity to move away. 

• Following the Bardolino development activities, a marine mammal report will be sent to 

the JNCC. 

Marine mammals would gradually be exposed to increasing levels of noise as they 

approached the development site. They would have time to react to this noise and move 

away from the source of disturbance. Marine mammals would be expected to return to the 

area once operations had ceased. 

The level of noise from drilling operations at and below the seabed would be lower than the 

noise from vessels. Noise can be minimised by the operation of well-maintained equipment 

during the drilling, and the choice of properly maintained vessels of a size appropriate to the 

task. The quality and suitability of the vessels would be considered in a tender evaluation 

process. 

Vessel, drilling and pipeline installation noise would not start suddenly, but would vary 

gradually increase throughout the course of the activities. The variable nature of the noise 

created by the relatively short-term activities would provide some opportunity for individuals to 

move away from, or not approach, sources of noise that would elicit strong avoidance 

reactions in them. 



6.8 INCREASED PRODUCED WATER DISCHARGES FROM NELSON 


Under OSPAR recommendation 2001/1 there is an expectation that there will be a zero 

discharge policy for new projects from 2002. For technical and economic reasons, however, 

it may not be possible to meet this baseline requirement for the Bardolino development. 

The discharge of produced water from offshore oil and gas installations in the UK is regulated 

by BERR. This is achieved by the use of legislation, in particular the Offshore Petroleum 

Activities (Oil Pollution Prevention and Control) Regulations 2005 (OPPC). 

The Nelson platform currently re-injects approximately 140,000 stb/d of water and at peak 

rates approximately 165,000 stb/d could be handled by the production and separation 

facilities on the platform. The produced water re-injection (PWRI) system currently operates 

at a 60% “up time” rate, i.e. it is operational for 60% of the time. These two factors mean that 

produced water discharge occurs continuously at Nelson and it can therefore be assumed 

that the total quantity of produced water from the Bardolino development will be discharged to 

sea. 

Due to the additional quantities of produced fluids that would be handled at Nelson, there will 

be a requirement to use additional quantities of Corrosion Inhibitor (CI) (see Section 3.7.5.). 

CI is currently used at a level of 200 ppmv on gross fluid production. CI is often observed to 

impair oil / water separation in produced water treatment systems, and therefore there is the 

potential for the amount of dispersed oil in discharged produced water to increase at Nelson 

as a result of the Bardolino development. The magnitude of any increase in the amount of 

dispersed oil in discharged produced water will depend on the quantity of fine solids in the 

produced fluids and the arrival temperature of the Bardolino fluids. 

The Nelson platform currently processes an average of 150,000 stb/d of produced water. It is 

anticipated that the Bardolino development will impose an additional peak load of produced 

water at Nelson of 1,300 stb/d in 2012 for the base case profile (P50 forecast of 50% 

likelihood of occurring). The additional Bardolino water will therefore represent less than 1% 

of the total throughput currently handled at Nelson. 

The total quantity of water discharged due to the Bardolino development over the life of the 

field is forecast to be between 2,162,000 bbl (High case or P10 forecast, i.e. 10% likelihood of 

occurring) and 4,147,000 bbl (Low case or P90 forecast, i.e. 90% likelihood of occurring). 

Shell estimates that, if the average concentration of dispersed oil in discharged produced 

water is 30 mg/l (in compliance with the OPPC permit for the Nelson facility), the additional 

produced water from the Bardolino development could result in the discharge of an additional 

19.7 t of oil to sea over the life of the Bardolino field, with a maximum discharge of 3.6 t per 

year. 


The permitted discharge of treated produced water into the marine environment can have an 

impact on water quality and pelagic organisms in a localised area immediately around the 

discharge point. Organisms that could be at risk include planktonic organisms (phytoplankton 

and zooplankton) and pelagic species of fish. 

At the Nelson platform, treated produced water with an oil-in-water concentration of


The species comprising the pelagic community at Nelson are mobile, and so would be 

unlikely to be exposed for a long period of time to the very locally enhanced concentrations of 

oil that might be present at the discharge point, and they are widely distributed in the water 

masses that flow over large areas of the North Sea (Section 4). There are no known 

sensitive pelagic invertebrate species at Nelson, and the amounts of oil that might reach the 

benthos would be infinitesimally small. It is therefore concluded that the permitted discharge 

of an additional amount of oil in produced water (estimated to be a maximum of about 3.6 t of 

oil each year) as a result of the Bardolino operations, would be unlikely to pose a significant 

threat to the viability or well-being of populations of plankton, or pelagic or benthic 

invertebrates. 

Fisheries sensitivity maps show that Nelson lies within the spawning areas for lemon sole, 

Nephrops, and Norway pout (Section 4.4.3). These species all spawn over wide areas of the 

North Sea, so the viability of the species would be unlikely to be impacted by the permitted 

discharge of produced water. 


The Nelson platform is more than 40 km from the UK/Norwegian median line. Given the low 

concentration of oil in the produced water discharge, and the effective and rapid dispersion 

and dilution to which produced water would be subject at the host location, it is considered 

unlikely that there would be any transboundary effects as a result of the additional produced 

water discharge originating from the Bardolino operations. 

It is estimated that the Bardolino development will increase the total volume of oil discharged 

annually in produced water at Nelson by a maximum of approximately 3.6 tonnes. It is 

considered that this relatively small contribution to the total volume of produced water 

discharged in the region would not result in a significant cumulative effect either locally or 

regionally, and would thus not cause a significant effect on the marine environment. There 

are not expected to be any global impacts associated with produced water discharges 

originating from the Bardolino development. 




Shell will monitor the impact on produced water quality from the increase in the quantity of 

corrosion inhibitor at Nelson to ensure that any impact is minimised. 

The increase in the total quantity of produced water discharged at the Nelson facility will be 

equivalent to less than 1% of the total quantity currently discharged by the facility. 

Engineering work is under way to improve the “up time” of the Nelson PWRI facility from the 

current level of 60% to 80%. This work is due to be completed prior to the start up of the 

Bardolino field and will ensure that a greater proportion of the fields’ produced water is reinjected 

into the reservoir, rather than being discharged to sea. 

The produced water from the Bardolino development would be treated by the existing 

produced water treatment system on the Nelson platform. Produced water would be treated 

so that at discharge the oil-in-water concentration of the produced water was well within the 

current BERR statutory limit of 30mg/l. 

The concentration of oil in produced water will be routinely monitored at least twice a day, 

using the method approved by BERR, and will be reported through the UK Environmental 

Emissions Monitoring System (EEMS). 



6.9 ACCIDENTAL SPILLAGE OF HYDROCARBONS 


All offshore drilling, development and production activities carry with them a potential risk, 

however small, of hydrocarbon spillage to sea. During 2005, a total of 438 hydrocarbon spills 

on the UKCS were reported to BERR, 10 of which were >1 t (BERR, 2008). The impact that 

may be caused by a spill is dependent on the location of the spill, its size, the properties of 

the hydrocarbon spilt, the prevailing metocean conditions at the time of the spill, the 

environmental sensitivities that could be impacted by the spill, and the success of the 

contingency plans. 

Spills can occur from a range of sources and can result in a number of different hydrocarbon 

types being spilt to the marine environment. Hydrocarbon spills include oil-based muds, base 

fluids, diesel and crude oil. Potential sources of environmental risk that could occur from 

accidental spills and non-routine events during the proposed Bardolino development activities 

include: 

• A small uncontrolled release of hydrocarbons resulting from re-fuelling the drilling rig. 

Spill records for offshore drilling operations indicate that spills of this nature are the 

most common way by which oil enters the sea from any drilling programme. 

However, they are still rare occurrences. 

• Historically, the major types of hydrocarbon spills from mobile drilling rigs have been 

oil-based drilling fluids, diesel and crude oil. There is a correlation between the 

number of reported spills and the number of wells drilled, but no consistent trend in 

the volume of hydrocarbons spilled from mobile drilling rigs has been found in data 

gathered since 1984 (DTI, 2001). The proportion of total oil spilled from mobile 

drilling rigs due to oil-based mud has dramatically decreased from approximately 65% 

in 1993 to


Shell is committed to preventing oil spills through the use of appropriate equipment that is 

properly maintained and operated by trained and environmentally aware personnel. 

6.9.2 Oil spill dispersion 

In order to model a credible worst-case scenario, stochastic and deterministic oil spill 

trajectory modelling has been carried out for the Bardolino development (BMT Cordah, 

2008b). 

Stochastic modelling takes its input data in the form of identified spill scenarios and actual 

statistical wind speed / direction frequency data (supplied by the Meteorological Office). The 

model then calculates a probability range of sea surface oiling representative of the prevailing 

conditions. 

Single deterministic modelling investigates the shortest beaching time, excluding prevailing 

weather conditions, and utilizes a standard set of conditions (i.e. 30 knot onshore wind) to 

deduce the worst case scenario, as required by the Maritime and Coastguard Agency (MCA). 

The potential sources of hydrocarbon spills identified and modelled for the Bardolino 

development represent: 

• a 50 m 3 oil spill. (a figure that represents the Bardolino to Howe pipeline inventory); 

and 

• a 1,000 tonne diesel spill. 

The diesel spill modelling has been completed for a worst-case scenario of 1,000 tonnes, 

which represents the biggest single release possible from any of the Mobile Offshore Drilling 

Units (MODUs) that are likely to be contracted by Shell for work in the Bardolino field, caused 

by collision with a vessel. Diesel oil has a relatively high evaporation rate, and a low 

persistence, therefore the slick would be localised and would disperse and degrade rapidly as 

a result of wave, current, microbial and photolytic action. 

Bardolino crude has not been characterised within the OSIS database, but Beryl crude oil has 

similar properties and has been selected as a `best-fit’ substitute, having a similar density and 

asphaltene content to Bardolino crude. 

Figure 6.6 to Figure 6.7 show the results from the stochastic modelling for the crude and 

diesel spills from the Bardolino location. 



Figure 6.6: Stochastic modelling results for the accidental release of 50 m 3 of crude oil 

from the Bardolino location (dark blue lines indicate territorial boundaries) 

Figure 6.7: Stochastic modelling results for the accidental release of 1,000 tonnes of 

diesel from the Bardolino location (dark blue lines indicate territorial boundaries) 

Figure 6.8 and Figure 6.9 show the predicted volumes of crude oil and diesel expected over 

time for the crude and diesel spill scenarios. 



Under the conditions modelled, no crude or diesel is expected to beach. Modelling using the 

OSIS spill model indicates that the 50 m 3 spill is expected to disperse naturally within 75 

hours, and the 1,000 tonne diesel spill would disperse within 8 hours of release. 

Figure 6.8: Volumes of oil in different phases over time for the Bardolino pipeline 

deterministic run. 

Oil Volume (m³) 

150.00 

125.00 

100.00 

75.00 

50.00 

25.00 

0.00 

0.00 25.00 50.00 75.00 

Time (h) 

Slick Volume 

Evaporated Volume 

Dispersed Volume 

Beached Volume 

Figure 6.9: Volumes of oil in different phases over time for the Bardolino diesel tank 

deterministic run. 

Oil Volume (m³) 

800.00 

700.00 

600.00 

500.00 

400.00 

300.00 

200.00 

100.00 

0.00 

0.00 1.00 2.00 3.00 4.00 

Time (h) 

5.00 6.00 7.00 8.00 

Slick Volume 

Evaporated Volume 

Dispersed Volume 

Beached Volume 



Figure 6.10: Deterministic modelling results for the instantaneous release of 50 m 3 of 

crude oil (dark blue lines indicate territorial boundaries) 

Figure 6.10 shows the results from the deterministic modelling of an instantaneous 50 m 3 

spill of crude oil. Under these conditions, modelling indicates that approximately 75 hours 

after release all of the oil would have dispersed naturally, and no crude oil would be expected 

to beach. 


The potential risk to birds from oil and diesel pollution is through damage to feathers resulting 

in loss of mobility, buoyancy, insulation and waterproofing. Birds may also be at risk from 

toxicity through ingestion of hydrocarbons and may face starvation through depletion of food 

sources. The birds most affected are those, such as guillemots, razorbills and puffins, that 

spend large amounts of their time on the water, particularly during the moulting season when 

they become flightless (DTI, 2001). 

Seabird vulnerability to oil pollution in the Bardolino area is “high” to “very high” during July, 

September, October and November, with “moderate” to “low” seabird vulnerability for the 

remainder of the year (JNCC, 1999; Section 4.4.5). High seabird vulnerability is attributable 

to the high numbers of guillemot and little auk in this part of the central North Sea (UKDMAP, 

1998). The Bardolino development activities are scheduled to occur between February and 

August 2009, which coincides with periods of high seabird vulnerability. The potential impact 

on seabirds is considered to be minimal, however, because the likely spills would be of diesel 

rather than crude oil, and any spilled diesel would be rapidly dispersed offshore. 

Major oil spills can result in direct mortality to marine mammals, although, generally, they are 

less vulnerable than seabirds to fouling by oil. 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. However, they are at risk from chemicals evaporating from the surface of an oil 

slick at sea, especially within the first few days; they may inhale vapours given off by spilt oil 

and their eyes may be vulnerable to major pollution, and individuals may drown as a result of 

associated symptoms. Neonatal (very young) seal pups are particularly at risk from oil 

coming ashore. In addition, a major release of oil or diesel may deplete marine mammals’ 

food supply (SMRU, 2001). 



There are several cetacean species which may occur regularly in the Bardolino development 

area, including minke whales, white-beaked dolphins, white-sided dolphins and harbour 

porpoises. Species such as killer, long-finned pilot and sperm whales, and common, Risso’s 

and bottlenose dolphins may also occur occasionally within the area (Section 4.4.4). 

However, there are probably only a few individuals in the Bardolino area at any one time, so 

the viability of any particular species is unlikely to be impacted in the event of a hydrocarbon 

spill. 

In fish life cycles, the egg and juvenile stages are the most vulnerable to spilt hydrocarbons, 

as adult fish are highly mobile and are generally able to avoid polluted areas. In the Bardolino 

area there are spawning grounds for mackerel (May to August), Nephrops (January to 

December, peak period is between April and June), lemon sole (April to September) and 

Norway pout (January to April) (Section 4.4.3). These species spawn over wide areas of the 

North Sea and spawning areas are not rigidly fixed, and may vary from year to year 

depending on response to changes in the surrounding environment. It is therefore considered 

that there will be no significant threat to any of these populations from accidental oil spills at 

the Bardolino location. The potential impact on fish is considered to be minimal, because the 

likely spills would be of diesel rather than crude oil, and any spilled diesel would be rapidly 

dispersed offshore and is unlikely to have any significant impact on the overall viability of 

these species. 

Table 6.12 summarises the potential effects of oil spills to marine life from offshore 

installations. The mitigation measures in place during the proposed operations (Section 

6.9.6) will ensure that the risk to these sensitive receptors is reduced to as low as possible. 

Table 6.12: Potential effects of oil spills in the offshore marine environment 

Environment Potential Effect 

Plankton Localised effects due to toxicity. 

Benthos Usually only localised effects from toxicity and smothering, and only if oil reaches the 

seabed. Benthic communities may be affected by gross contamination, with recovery taking 

several years. 

Fish Adult fish are expected to leave the affected area. Eggs and larvae may be affected by 

toxicity, but such effects are generally not considered to be ecologically important. 

Seabirds Physical fouling of feathers and toxicity can result in fatalities. Effects will depend on species 

present, their abundance and time of year. Birds are identified as being most vulnerable in 

the Bardolino area during September. 

Marine mammals No obvious effects are known for adult cetaceans or seals. Fouling of the fur of young seals 

reduces their resistance to cold. 


The Bardolino development lies approximately 40 km from the UK/Norway median line and in 

the event of a serious spill of the total inventory from the Bardolino pipeline, of the magnitude 

modelled above, the slick may be expected to spread into Norwegian waters. A major 

hydrocarbon spill of this magnitude could therefore potentially have a trans-boundary impact. 

Major incidents of this magnitude would have a very low probability of occurrence. 

The loss of well control resulting in the release of gas to the atmosphere would affect a 

localised area, but would then be rapidly dispersed in the energetic atmospheric conditions 

offshore and would therefore not have any trans-boundary impacts. The release of any gas 

would contribute relatively small quantities of materials with global warming potential to the 

atmosphere. 

Cumulative impacts occur as a result of a number of activities, discharges and emissions 

combining, potentially to create a significant impact. Any hydrocarbon discharges as a result 

of the Bardolino Development would be expected to disperse rapidly in the immediate 

environment without the potential to combine with other discharges, therefore any significant 

cumulative impacts are unlikely. 

Any interference with fishing and other offshore activity would be short-lived. 






During drilling activities the well would be controlled in accordance with Shell Well 

Engineering Information System Drilling Procedures, to prevent the accidental release of oil 

and gas. The Shell Oil Spill Response Procedure covers the actions that would be taken in 

the event of any spill during the drilling operation. 

The planning, design and support for the drilling operation aims to reduce environmental risks 

to a minimum. Primary well control would be achieved through the appropriate use of muds 

and weighting agents in accordance with principles and procedures laid out in the current 

Shell Well Engineering Information System. A blow-out preventor (BOP) would be installed 

on the well and tested regularly. The purpose of a BOP is to prevent the uncontrolled release 

of gas and oil from the wells; it consists of a series of heavy-duty valves attached at the top of 

the casing. Staff would have received standard industry training in blow-out prevention. In 

addition, all transfers of hazardous fluids (e.g. diesel) to the rig would be carried out under the 

control of rig-specific procedures and in accordance with the Shell Marine Operations Manual. 

There would be a statutory 500 m safety zone around the drilling rig. Local shipping traffic 

would be informed of its position and a standby vessel would monitor shipping traffic at all 

times. Prior to any rig moves a warning would be issued to the appropriate authorities, as 

required by the Health & Safety Executive (HSE) Operations Notice 6 (HSE, 1997). 

Vessels other than those involved in the operation would not be permitted to enter the safety 

zone for the duration of the operation. 

All loading operations to the drilling rig would be carried out in accordance with the Shell 

Marine Operations Manual, thus minimising the potential for loss of containment. With regard 

to diesel transfer from supply vessels to the rig, standard operating procedures would be used 

which include ensuring all the equipment is sealed and having personnel on deck to check for 

any signs of spillage. In the unlikely event that a spillage did occur, it would be extremely 

small, and operations would immediately cease until the problem had been identified and 

corrected. 

During operation of the facilities, pipelines would be subject to an inspection and maintenance 

programme designed to check their integrity and provide early warning of problems. 

Production would cease if any significant loss of pressure, indicating loss of containment, 

were detected. 

Even with comprehensive prevention measures in place, however, there is still a residual risk 

that oil may be spilled. The Shell U.K. Limited general Oil Spill Contingency Plan ‘Oil Spill 

Response Procedures’ (3149-001) cover the actions that would be taken in the event of any 

spill during the drilling operation and is currently applicable to all North Sea operations. The 

Bardolino development would also be covered by the Nelson Field System Oil Spill Plan 

(3149-033) which complies with the Merchant Shipping (Oil Pollution Preparedness, 

Response and Co-operation Convention) Regulations 1998 requirements. In addition, 

response to spills would be specified in the Rig’s Emergency Procedures. 

The Bardolino development project would not significantly increase the overall level of risk of 

an oil spill from existing facilities in the area, due to the very low probability of an incident 

occurring. The mitigation measures and contingency plans in place would consider all 

foreseeable spill risks and would ensure that the spill risk is reduced to as low as reasonably 

practicable. The contingency plans would ensure that an appropriate response is made to 

any spill in order to minimise any impact on the environment. 






7 CONCLUSIONS 

7.1 PROJECT OVERVIEW 

The Bardolino development activities include: 

• Well Engineering 

• Subsea Infrastructure Installation and Commissioning 

• Existing Facilities Modification and Commissioning 

• Production, Utility and Maintenance Operations 

• Well Abandonment and Decommissioning 

Each activity has potential sources of emissions, discharges and waste or other 

environmental impacts, including accidental events. Those sources identified in this 

assessment are considered to be typical of the UK offshore industry. There are no unusual or 

unique emissions, discharges or other potential sources of environmental impact. 

7.2 LOCAL ENVIRONMENT 

In terms of marine flora and fauna, the location of the Bardolino Development is typical of the 

central North Sea. While recognising that there are certain times of the year when 

populations of seabirds, fish spawning and commercial fisheries are vulnerable to surface oil 

pollution, it is concluded that the area is not particularly sensitive to a development of the type 

proposed. 

Of the four Annex I habitats listed in the Habitats Directive known to occur in UK offshore 

waters, biogenic reefs and ‘submarine structures made by leaking gases’ are present in the 

central North Sea. The proposed Bardolino development is located outside the Witch Ground 

and known gas seep areas. The Scanner Pockmark (dSAC) in Block 15/25 and Braemar 

Pockmarks (dSAC) in Block 16/3 are located approximately 67 km and 146 km, respectively, 

from the proposed development site. No pockmarks were identified during the anchor 

conditions survey. 

Of the four species listed on Annex II of the Habitats Directive known to occur in UK waters 

for which selection of offshore SACs will be considered, the harbour porpoise was the only 

species recorded within the proposed development area (Quadrant 22). Harbour porpoises 

are present throughout most of the North Sea throughout the year, with higher numbers 

occurring between May and October, but in the area of the proposed development numbers 

and occurrence are likely to be low. 

7.3 POTENTIAL IMPACTS 

This assessment identified the following eight potential impacts as being of greatest 

significance to the environment: 



• the discharge of water-based mud and cuttings from the development well; 

• the atmospheric emissions that would arise from the Bardolino development; 

• the local disturbance to the seabed caused by pipeline trenching and possible 

backfilling, rock dump stabilisation and mattressing; 

• installation and physical presence of the subsea structures (manifold, tree and valve 

skid); 

April 2008 Page 7-1


• underwater noise that would be created during the installation of the Bardolino 

facilities; 

• discharge of produced water at the Nelson platform; and 

• any accidental hydrocarbon spillage or release. 

7.7.1 The physical presence of the drilling and support vessels (including anchoring) 

A semi-submersible drilling rig would be used to drill the Bardolino development well. The 

drilling rig would be moored on location by 8 anchors, in a pre-determined ‘anchor pattern’. 

The use of anchors to position and moor the drilling rig would result in the physical 

disturbance of the seabed sediments and bottom-dwelling fauna in localised areas around the 

anchors (chains and wires) during their deployment and retrieval. 

Depending on the nature of the seabed, anchors can create mounds on the seabed up to 1 m 

high, while anchor chains lying on, and sweeping over, the sediments can create gouges and 

scour marks. Anchor mounds can form on clayey sediments, and because of the stiffness of 

clay they have the potential to become long-lived seabed features that may represent 

obstructions to mobile fishing gear deployed on the seabed. Surveys have shown that the 

seabed in the Bardolino area comprise fine sandy sediments, which have occasional 

exposures of the underlying clay. 

The deployment and retrieval of anchors from the drilling rig would cause localised temporary 

disturbance to the seabed over an estimated total area of 1 km 2 . The anchoring operations 

would all be within UK waters, so there would be no trans-boundary impacts. The anchor 

pattern that would be used, and the placement and removal of the anchors, would be carefully 

planned. 

For other users of the sea, access around the drilling rig would be restricted for the period 

during which drilling will take place. All the anchors would be completely removed from the 

seabed at the end of the drilling programme before the rig departs. The impact of anchoring 

the drilling rig is therefore considered to be insignificant. 

7.7.2 The discharge of water-based mud and cuttings from the development well 

Water-based mud will be used during riserless drilling of the 36” and 26” sections of 

development well and cuttings from these sections will be discharged directly onto the seabed 

at the well site. The cuttings deposited on the seabed may have a short term smothering 

effect on fauna living on the seabed, and on the fish spawning grounds, in the immediate 

vicinity of the well location. 

Recovery of the habitat would be enhanced by the dispersion, dilution and breakdown of the 

chemicals within the cuttings which would be brought about by the existing metocean current 

regime. Spreading and natural dispersion of the cuttings would occur as a result of sediment 

movement in the area. Bioturbation, caused by the action of burrowing seabed-dwelling 

organisms, would also aid this process. These effects would minimise any smothering that 

might occur in a region where the tidal currents are sufficiently weak to permit the deposition 

of the cuttings. Re-colonisation of the area by seabed-dwelling animals is predicted to occur 

very readily. 

Low toxicity oil-based mud will be used the remaining sections of the development well. The 

cuttings derived from these sections will be returned to the drilling rig where they will be totally 

contained, and then returned to shore for treatment and disposal. 

All drilling chemicals or products (including cementing products) require a permit for use and 

discharge offshore, and they would be subject to a chemical risk assessment prior to drilling 

as required by the Offshore Chemical Regulations 2002. This would provide Shell with an 

opportunity to consider alternative chemicals where the outcome of the risk assessment is 

shown to be unfavourable. The effect of the proposed drilling discharges is considered to be 


Page 7-2 April 2008


7.7.3 The atmospheric emissions arising from the Bardolino development 

Flaring of oil and gas to clean-up the development well would release combustion gases into 

the atmosphere. These have the potential to contribute to global / regional atmospheric 

effects such as global warming and photochemical pollutant formation. The clean-up 

operation would be limited to a total testing and clean-up period of 48 hours with a maximum 

of 15,000 bbls (1,900 tonnes) of oil with an expected GOR of 870 scf/bbl flared. 

Well clean-up procedures would be in place to ensure that the operation is carried out as 

efficiently as possible. High-efficiency flare burners will be used, and they will be operated to 

ensure they were working as efficiently as possible, in order to minimise emissions. 

The consumption of diesel fuel for vessel operations associated with drilling the development, 

installing the pipelines and umbilical, and installing the structures on the seabed, would result 

in the generation of carbon dioxide and other exhaust gases. 

From a global perspective, the levels of the emissions from the Bardolino development 

represent a very small proportion of total emissions arising from all UK offshore well testing 

and production activities, and will make a negligible contribution to global / regional 

atmospheric processes. 

7.7.4 Localised disturbance to the seabed from the installation and mattressing of 

the pipeline 

A 2 km gas export pipeline (piggybacked by a 3” chemical pipeline), and a separate umbilical 

would be laid between the Bardolino well and the existing Howe manifold. The pipelines and 

umbilical would be laid in two separate trenches. The trenching of the pipelines and umbilical 

has the potential to impact the seabed sediment and organisms living within it. 

The trenching operations would disturb the seabed along a 6 m wide corridor at the top of a 

deep ‘vee’-shaped trench. A narrow 2 m wide band of seabed on either side of each trench 

would be affected by the deposition of soil excavated from the trenches, and it is estimated 

that a total area of 0.02 km 2 of seabed would be temporarily impacted by the trenching 

operations. 

It is anticipated that a total of approximately 130 concrete mattresses; 60 at the Bardolino 

manifold transition zone and 70 at the Howe manifold transition zone would be required to 

stabilise either end of the pipelines. The concrete mattresses would typically be 6 x 3 x 0.15 

m in dimension, with mattresses 6 x 3 x 0.3 m in dimension in areas of high risk to dropped 

objects. The total area of seabed that would be covered by the mattresses would be 

approximately 0.0023 km 2 . 

There are no proposed or designated conservation sites in the immediate vicinity of the 

Bardolino development. Access to other sea users along the pipeline route would be 

restricted for the period during which installation will take place. 

7.7.5 Installation and physical presence of the subsea structures 

The installation of a new production manifold, a production tree and a valve skid would result 

in highly localised physical disturbance of the seabed sediments and associated fauna. This 

would result in loss of habitat in the area directly below the subsea structures, with 

consequent impact on the seabed-dwelling organisms. 

The subsea structures are located in an area of low commercial value for all fish species 

caught by UK fishermen in comparison to all areas fished around the UK. The main fishing 

gears used in the area are demersal / bottom trawling methods which have the greatest 

potential to interact with subsea structures. 

The subsea structures would be enclosed within protective tubular steel frames, which are 

designed to have a fishing-friendly profile. No significant operational problems for demersal 

trawling are foreseen from the presence of the protected structures on the seabed. 

April 2008 Page 7-3


7.7.6 Underwater noise that would arise from the Bardolino development 

Underwater noise would be generated from activities associated with the Bardolino 

development. The main source of underwater noise would be from piling the subsea 

structures to the seabed. The duration of the piling activities would be approximately 12 

hours for each structure, and the two piling operations would not be contiguous. Marine 

mammals could be impacted by noise during these operations and they may take avoidance 

action if they are disturbed, but evidence indicates that they would return once activities have 

ceased. 

Densities of cetaceans in the area are low compared to other areas of the North Sea. Noise 

levels from these activities are predicted to be equivalent to noise emanating from shipping 

and seismic activities, and are unlikely to cause anything more than a temporary local 

disturbance to marine mammals. 

Shell will ensure that piling will only begin during daylight hours and that a JNCC approved 

marine mammal observer (MMO) would be present on the standby vessel throughout the 

operations, to monitor the presence of marine mammals in the area. Piling would only begin 

when it was confirmed that marine mammals were not present in a circular zone of 1 km 

radius, centred on the piling site. A “soft start” would be undertaken for each new period of 

piling, so as to alert marine mammals in the area and give them the opportunity to move 

away. 

7.7.7 Discharge of produced water at the Nelson platform 

The Bardolino development will result in an increase in the quantity of produced water 

discharged at the Nelson platform; the increase is likely to be


The mitigation measures and contingency plans in place would consider all foreseeable spill 

risks and would ensure that the spill risk is reduced to as low as reasonably practicable. The 

contingency plans would ensure that an appropriate response is made to any spill in order to 

minimise impact on the environment. 

7.4 MITIGATION MEASURES 

Shell is committed to environmental protection in this and all its offshore operations. The 

activities associated with the Bardolino development will be conducted in accordance with 

Shell’s Corporate Management System (CMS). The procedures that support this 

management system will put robust environmental safeguards in place as detailed in this 

Environmental Statement. 

A summary of the main commitments in the ES for the Bardolino development are 

summarised in Table 7.1: 

Table 7.1: Summary of Shell environmental commitments for the Bardolino 

development 

Activity Shell Commitments 

Presence of rig and vessels, 

including anchors 

Discharge and disposal of 

mud, cement and cuttings 

• Anchor placements will be carefully planned and managed and 

interface documents will be set up between contractors and 

Shell. 

• The Hydrographic Office will be notified to issue Notices to 

Mariners, and contact information and details of guard vessels 

will be given. 

• Guard vessels will be on station during drilling and pipeline 

installation operations. During drilling, the standby vessel would 

monitor the activity of all other vessels in the vicinity of the 

drilling site. 

• All anchors will be completely removed on completion of the 

drilling programme. 

• WBM will be used for the top-hole sections of the well. 

• As far as possible the WBM will comprise PLONOR or low HQ 

chemicals and all chemicals will be risk-assessed and submitted 

to BERR as part of the PON15B application. 

• LTOBM-coated cuttings will not be discharged but will be 

returned to the rig, contained and shipped to shore for reprocessing 

and disposal. 

• The amounts of chemicals and cement required would be 

calculated accurately and the operations carefully planned, to 

minimise the amounts actually used. 

Well testing and clean-up • No extended well test is planned. 

• Procedures will be in place to ensure that the operation is 

carried out as efficiently as possible. 

• Flare burners will be of high efficiency and maintained and 

monitored by trained operators. 

• The wind direction will be monitored to adjust the flare to 

optimum position. 

• The sea state below the burner will be monitored to detect the 

presence of any oil sheen from flare drop-out. 

Gaseous emissions from power 

generation on drilling rig or 

vessels 

Discharge to sea of drainage 

water, sewage or disposal of 

solid waste from the drilling rig 

and vessels 

• All engines, generators and other combustion plant would be 

well maintained and correctly operated, to ensure that they 

were working as efficiently as possible to minimise emissions. 

• There would be systems in place on the rig to ensure that 

drainage discharges complied with MARPOL. This requires that 

the rig must be fitted with oil-water separation and filtration 

equipment, to ensure that the concentration of oil in any 

discharged water is less than 15ppm. 

April 2008 Page 7-5



• The rig would have UK or International Oil Pollution Prevention 

certification for its drainage systems. 

• Sewage would be macerated on the rig to aid biological 

breakdown once discharged into the sea. 

• Food waste would be macerated as required by MARPOL and 

Merchant Shipping (Prevention of Pollution by Garbage) 

Regulations 1998; this would aid its dispersal and decomposition 

in the water column. 

• All other waste would be segregated and contained, and then 

shipped to shore for recycling or disposal by a licensed company 

in full compliance with UK waste legislation and Duty of Care 

and Shell’s policies. 

• Shell will regularly audit its approved onshore waste disposal 

contractors, to ensure all procedures and legal requirements are 

adhered to. 

Pipeline installation, rock dump 

stabilisation and mattressing 

Installation and presence of 

manifold, tree and valve skid 

Commissioning and testing of 

pipelines, umbilical, manifold 


• A pipeline route corridor survey will be undertaken including soil 

samples and underwater photography, to help select the 

optimum pipeline route and installation method. The results of 

this survey will be submitted to BERR along with the PON15C 

application. 

• DP installation vessels will be used to minimise anchor scars. 

• A fall pipe will be used on any rock dump vessel with ROV 

supervision to ensure rock is placed correctly. 

• Necessary licences would be obtained by Shell prior to any rock 

dumping activity. 

• Tie-in spools at Bardolino will be designed to prevent snagging 

of fishing gear, and will be protected from dropped objects 

using concrete mattresses. 

• The positions of sub-sea infrastructure will be clearly marked on 

charts and notices to mariners. 

• Mattresses will be designed to minimise the risk of snagging 

from bottom-towed fishing gear. 

• The location and profile of any spot rock dump material would 

be made available to fishermen and fishing interests. 

• DP installation vessels will be used to minimise anchor scars. 

• A post-lay survey of the seabed will be conducted by Shell to 

verify that the structures are installed according to plan, and 

that they are over-trawlable. 

• The subsea structures and their protective structures would be 

designed to ensure that they do not impede fishing activities 

and would withstand fishing interaction loads and dropped 

object loads. 

• Only the types and amounts of chemicals essential to 

demonstrate the integrity and fitness of the pipeline would be 

used. 

• The chemicals would be carefully selected so as to minimise 

potential environmental effects, in accordance with Offshore 

Chemical Regulations 2002. 

Piling operations • DP installation vessels will be used to minimise anchor scars. 

• Shell will follow its piling procedures during activities at 

Bardolino as agreed with JNCC (Appendix 4). This will include 

restricting activities to daylight hours, the use of a suitably 

qualified MMO to ensure marine mammals are outside a 1 km 

radius area for at least 30 minutes prior to starting activities, 

and undertaking a “soft start” to piling. 

• All activities will be carried out in line with Shell HSE policy and 

current legislation 

Page 7-6 April 2008



Discharge of produced water 

at Nelson 

• Shell will monitor the impact on produced water quality from the 

increase in the quantity of corrosion inhibitor at Nelson, to 

ensure any impact is minimised. 

• Engineering work is under way to improve the “up-time” of the 

Nelson PWRI facility, and this is due to be completed prior to 

the start up of Bardolino. 

• Produced water will be treated to ensure that its oil-in-water 

concentration is within the 30 mg/l limit. 

• The concentration of oil in produced water will be routinely 

monitored at least twice a day using the method approved by 

BERR and reported through EEMS. 

Accidental spills • Drilling activities will be controlled in accordance with Shell Well 

Engineering Information System Drilling Procedures. 

• A BOP will be installed and tested regularly. 

• Staff will be trained in blow-out prevention. 

• All transfers of hazardous fluids to the rig would be carried out 

under the control of rig-specific procedures and in accordance 

with the Shell Marine Operations Manual. 

• There will be a 500 m safety zone around the rig. 

• A warning will be issued to the appropriate authorities prior to 

any rig move. 

• All loading operations will be carried out in accordance with the 

Shell Marine Operations Manual. 

• During diesel transfer standard operating procedures would be 

used, including ensuring all equipment is sealed and having 

personnel on deck to check for signs of spillage. 

• During production operations, pipelines will be subject to an 

inspection and maintenance programme. 

• The Bardolino development would be covered by the Nelson 

Field System Oil Spill Plan (3149-033) and response to spills 

would be specified in the Rig’s Emergency Procedure. 

7.5 CONCLUSIONS 

In overall terms, development of the Bardolino field is not expected to lead to environmentally 

significant effects. The proposed development is located in an area that is typical of the 

central North Sea in terms of habitats and marine life. None of the environmental receptors is 

assessed as being particularly sensitive to the type of drilling, subsea installation or pipelaying 

activity proposed. 

This assessment demonstrates that the drilling of the Bardolino well, and the installation of 

the manifold and the pipelines, will have no significant effects on environmental resources in 

Blocks 22/11, 22/12 and 22/13 of the central North Sea. 

April 2008 Page 7-7



Page 7-8 April 2008


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Page 8-4 April 2008


APPENDIX 1 RELEVANT ENVIRONMENTAL LEGISLATION 

This Appendix presents summaries of the main environmental regulatory requirements that 

will apply to the Bardolino Development. 

Controlled Waste Regulations 1992 

These regulations require the categorisation and segregation of wastes, the transfer by 

authorised waste carriers and disposal to licensed sites. 

Deposits in the Sea Exemptions Order 1985 

This Order exempts all non-oil discharges, including chemicals, drilling cuttings and muds, 

associated with the exploration and production of oil and gas from licensing requirements of 

the Food and Environment Protection Act 1985. 

EC Directive 2003/4/EC on public access to information 

The Directive transposes the first pillar of the Aahrus convention; access to information, into 

EU legislation requiring all public authorities to provide members of the public with access to 

and to disseminate, the environmental information they hold. The information must be 

provided to any person at their request, without them having to prove an interest and at the 

latest within two months for the request being made. 

Energy Act, 1976 

This Act is mostly used for issue of vent consents, although it also covers some flaring which 

has not been permitted under licence model clauses. 

Environmental Information Regulations 2004 

The Regulations implement EC Directive 2003/4/EC in the UK. The Regulations give a 

statutory right of access to environmental information held by public authorities and 

organisations with public authority responsibilities. 

Environmental Information (Scotland) Regulations 2004 

The Regulations implement EC Directive 2003/4/EC in Scotland and to establish an access 

regime allowing the public to request information from Scottish public authorities. 

Environmental Protection Act, 1990 

This Act and associated Regulations brought into effect a system of regulation for “controlled 

waste”. Although it does not apply to offshore installations it requires operators to ensure that 

offshore waste is handled and disposed onshore in accordance with the “duty of care” 

introduced by the Act. 

Espoo Convention 

The 1991 UNECE Convention on Environmental Impact Assessment in a Transboundary 

Context (the Espoo Convention) requires any country that has ratified the convention to 

consider the transboundary environmental effects of industrial projects and activities, 

including offshore hydrocarbon exploration and productions activities. 

The Convention requires that if the activity is found to cause a significant adverse 

transboundary impact then the party undertaking the activity shall, for the purpose of ensuring 

adequate and effective consultations, notify any potentially affected as early as possible. 

Food and Environment Protection Act, 1985 

This Act was introduced primarily to meet the requirement of the Oslo Convention and 

prohibits the placing or depositing of any materials on the seabed unless a licence has been 

granted by the regulatory authority. In Scottish waters, FEPA licenses are issued by FRS 

(Fisheries Research Services) on behalf of DTI. 

April 2008


The Merchant Shipping Act 1995 

This Act implements the International Convention on Oil Pollution Preparedness, 

Response and Co-operation (OPRC Convention) in the UK. The aim of the OPRC 

Convention is to increase the level of effective response to oil pollution incidents and to 

promote international co-operation to this end. The Convention applies to ships and offshore 

installations and requires operators to have in place oil pollution emergency plans, which are 

approved by the body that is the National Competent Authority for the Convention. 

Merchant Shipping (Prevention of Oil Pollution) Regulations 1996 

This Regulation and earlier versions established controls required by the MARPOL 

convention on oily water from machinery spaces and non-hazardous drains discharges from 

vessels and installations in “Special Areas”, which now includes the North Sea. The 

regulations are designed to limit oil in discharged water to 15ppm. 

Merchant Shipping (Prevention of Pollution by Garbage) Regulations 1998 

These Regulations place additional requirements on waste disposal from vessels and 

offshore installations, including requirements to have waste management plans and to keep a 

waste record book. 

Merchant Shipping (Oil Pollution Preparedness, Response and Co-operation 

Convention) Regulations 1998 

These regulations introduce specific requirements for each offshore installation to have an 

approved oil pollution emergency plan in place by 15th August 1999. Shell Expro maintains 

oil spill contingency plans to meets its response requirements. 

Oil spills from offshore installations must be reported to the Coastguard, DTI and other 

specified parties under the arrangements described in Petroleum Operations Notice No. 1 

and administered by DTI. 

National Emission Ceilings Regulations 2002 

These regulations set national ceilings and a requirement for the development of a reduction 

programme for sulphur dioxide, nitrogen oxides and volatile organic compounds in the UK. 

Offshore Chemical Regulations (OCR) 2002 

In June 2000, OSPAR introduced Decision 2000/2 on a Harmonised Mandatory Control 

System for the Use and Reduction of the Discharge of Offshore Chemicals. In the UK, this is 

administered under the Offshore Chemical Regulations 2002 (OCR 2002), which came into 

force on 15 May 2002. 

Offshore chemicals must be ranked according to their calculated Hazard Quotients (HQ – 

ration of Predicted Environmental Concentration (PEC) to Predicted No Effect Concentration 

(PNEC)). It also obliges authorities to use the CHARM “hazard assessment” module as the 

primary tool for the ranking. 

Inorganic chemicals and organic chemicals with functions for which the CHARM model has 

no algorithms will continue to be ranked using the existing Offshore Chemical Notification 

Scheme (OCNS) hazard groups. Chemicals are now listed using a banding system to rank 

organic chemicals of similar function according to PEC:PNEC “Hazard Quotients” calculated 

using the CHARM model. 

Offshore Combustion Installations (Prevention and Control of Pollution) Regulations 

2001 

These regulations came into force on 19 th March 2001 under the Pollution Prevention and 

Control (PPC) Act 1999. A permit will now be required in order to operate an offshore 

combustion installation with an input of more that 50 megawatts (Regulation 3). An existing 

qualifying combustion installation (defined in Regulation 2) will not require a permit until 30 th 

October 2007 unless, prior to that date, it is subject to a change which is a substantial change 

in the opinion of the Secretary of State (Regulation 3(2)). 

April 2008


Offshore Marine Conservation (Natural Habitats &c) Regulations 2007 

The Offshore Marine Conservation (Natural Habitats, &c) Regulations 2007 came into force in 

August 2007. The regulations extend protection to important species and habitats under the 

Wild Birds and Habitats Directives beyond UK territorial waters. Under the amended 

regulations it is an offence to deliberately disturb any marine European protected species. A 

wildlife licence can be issued in the offshore (beyond 12 nautical miles) marine area 

authorising a range of activities in that would otherwise be prohibited. 

Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 as amended 

The Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 seek to 

ensure that oil and gas activities on the United Kingdom Continental Shelf are carried out in a 

manner that is consistent with the requirements of the Habitats Directive. Such requirements 

will also include, by way of Articles 3 and 7 of the above directive, any SPAs classified under 

the associated Wild Birds Directive. The Regulations do not cover any other marine activities 

nor do they themselves make provision for a procedure for designation or classification of 

sites on the UKCS. They do, however, require the Secretary of State to have regard to both 

designated and classified sites under both Directives and sites, which in his opinion are likely 

to be designated or classified under these Directives. 

The Regulations place a general requirement on the Secretary of State to do what he thinks 

necessary to ensure that oil and gas activities are carried out in a manner that is consistent 

with the Habitats Directive. The Regulations prohibit the Secretary of State from granting an 

oil and gas licence, consent, approval or authorisation, without first determining whether the 

effect of such activities is significant and, if so, undertaking an appropriate assessment to 

determine whether such activities are likely to have an adverse effect on the integrity of such 

sites. 

In the light of the conclusions of the above assessment, and subject to a national interest 

exception (Article 6(4) of the Directive), the Secretary of State may grant a licence, consent, 

approval or authorisation only after having ascertained that the activity would not have an 

adverse effect on the integrity of a relevant site. 

Offshore Petroleum Activities (Oil Pollution Prevention and Control) Regulations 2005 

The Offshore Petroleum Activities (Oil Pollution Prevention and Control) Regulations 2005 

have the objective of more stringent, manageable regulation of oil discharge by the offshore 

oil and gas industry. The regulations propose this is achieved by updating the definition of oil, 

introduce more wide-ranging powers for inspectors to monitor and investigate oil discharges, 

introduce a system of permits for oil discharges and authorise a trading scheme to reduce the 

amount of dispersed oil discharge in produced water arising from the requirements of an 

international commitment. 

Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) 

Regulations 1999 as amended 

These Regulations require operators to submit an Environmental Statement for all new 

offshore developments or to obtain a dispensation from this requirement. 

Offshore Installations (Emergency Pollution Control) Regulations 2002 

These regulations require OSCPs to be revised to include: 

April 2008 

• The involvement of the Secretary of State Representative (SOSREP) in any 

incident via the Operator provided Emergency Response Centre; 

• Changes to reporting requirements to reflect this; 

• Notification changes to oil spill reporting – namely provision for differentiating 

between four types of spill – potential spill, chemical spills, oil spills; produced 

water spills. 

Prevention of Oil Pollution Act (POPA) 1971, as amended 

This Act and its associated Regulations prohibits the discharge of oil or oily mixtures to sea 

from any offshore installation or pipeline. This Act remains in force, however the 

requirements of applicable sections do not apply to discharges of oil, which are regulated by a


permit under the OPPC Regulations. The Act provides for exemptions to be obtained for 

routine oily discharges in order that an offence is not committed. Accidental oil spills cannot 

be exempted and these are therefore illegal discharges. Defences can be made that if 

accepted can avoid prosecution. 

Petroleum Act, 1998 

This Act includes a requirement for a Pipeline Works Authorisation for new subsea pipelines 

for oil, gas, water, chemicals. The Act includes a requirement for consent to discharge 

pipeline pre-commissioning and commissioning discharges of chemically-treated water. The 

consent includes the specified chemical constituents, the permitted volume and rate of 

discharge and the environmental conditions under which the discharges may take place. The 

chemicals are further regulated under the voluntary Offshore Chemicals Notification Scheme 

(see below). 

The Act also covers consents for flaring of gas, and the abandonment of offshore 

installations. 

Radioactive Substances Act, 1993 

Solid particles and precipitated material that arises from the hydrocarbon reservoirs can form 

loose deposits of sludge or hard deposits in vessels, pipework and equipment. The natural 

content of radiation of the reservoirs can be such that the deposits must be regulated under 

this Act, requiring an authorisation to be in place in order to accumulate or dispose of the 

material. This material is called low specific activity (LSA) scale or normally occurring 

radioactive material (NORM). 

Special Waste Regulations 1996 

This legislation does not strictly apply offshore. However, because the offshore disposal of 

garbage is prohibited then all wastes must be transferred to shore for disposal. Once 

onshore, the wastes must meet the requirements of onshore legislation when being disposed. 

These regulations must therefore be considered offshore to allow onshore requirements to be 

met. 

The Control of Pollution (Special Waste) Regulations, 1996 

These Regulations require controlled wastes that are also considered to be special wastes 

because of their hazardous properties, to be correctly documented, recorded and disposed at 

an appropriately licensed site. The Regulations also apply to special waste that is returned 

from offshore installations to shore for disposal. 

April 2008


APPENDIX 2: HEALTH, SAFETY AND ENVIRONMENTAL POLICY 

April 2008


APPENDIX 3 CONSULTATION LETTER AND RESPONSES 

This Appendix presents a copy of the consultation letter sent to consultees on 13 th March 

2008 and copies of responses received. 

The consultation letter was sent to the consultees listed below: 

April 2008 

Organisation Contact Details 

Department for Business, Enterprise & 

Regulatory Reform 

Mr Phil Bloor 

The Offshore Environmental Unit 

Department for Business, Enterprise & Regulatory 

Reform 

Atholl House 

86- 88 Guild Street AB11 6AR 

Marine Conservation Society Marine Conservation Society 

Unit 3, Wolf Business Park 

Ross-on-Wye 

Herefordshire HR9 5NB 

Royal Society for the Protection of Birds Royal Society for the Protection of Birds 

Dunedin House 

25 Ravelston Terrace 

Edinburgh EH4 3TP 

Scottish Fisherman’s Federation Mr Michael Sutherland 

Scottish Fisherman’s Federation 

24 Rubislaw Terrace 

Aberdeen AB10 1XE 

Joint Nature Conservation Committee Craig Bloomer 

Joint Nature Conservation Committee 

Dunnet House 

7 Thistle Place 

Aberdeen AB10 1UZ 

Defence Estates 

Defence Estates 

Graesser House 

Sutton Coldfield 

West Midlands C75 7RL 

Coastguard, Aberdeen, Offshore Oil & 

Gas Team 

Coastguard Agency, Marine Pollution Control 

Unit 

Coastguard, Aberdeen 

Offshore Oil & Gas Team 

2 nd Floor 

Marine House 

Blaikies Quay 

Aberdeen AB11 5PB 

Coastguard Agency 

Marine Pollution Control Unit 

Spring Place 

105 Commercial Road 

Southampton SO15 1EG 

FRS Marine Laboratory Mr James Mckie 

FRS Marine Laboratory 

PO Box 101 

375 Victoria Road 

Aberdeen 

Scottish Government Marine Directorate Scottish Government Marine Directorate 

Marine Strategy Team 

Marine Management Division 

Area G-H93 

Victoria Quay 

Edinburgh EH6 6QQ

13 th March 2008 

Dear Sir or Madam, 

Bardolino Field Development – Central North Sea 

Shell U.K. Limited 

Registered in England number 140141 

Registered office Shell Centre London SE1 7NA 

VAT reg number GB 235 7632 55 

Shell U.K. Limited 

Seafield House 

Hill of Rubislaw 

Anderson Drive 

Aberdeen 

AB15 6BL 

United Kingdom 

Tel +44 (0)1224 882000 

Email Bill.Gray@shell.com 

Internet 

http://www.shell.com/eandp 

I am writing to inform you that Shell U.K. Limited has started preparations to develop the Bardolino 

field located on the Northern edge of the East Central Graben of the Central North Sea. The field will 

be developed by one subsea well tied into the existing Howe Pipeline Tie-in Structure (PTS), 

approximately 2km to the West of the proposed Bardolino spud location. Bardolino fluids will be 

commingled with Howe fluids and evacuated to the Nelson platform via the Howe-Nelson pipeline. 

The Bardolino discovery is located primarily in UKCS block 22/13a, some 16km east of the Nelson 

platform and 2km east of the Howe field. The field was discovered by the 22/13a-1 well, which was 

drilled in late 1988. This well tested oil from both the Kimmeridge and Fulmar formations 

The proposed recovery mechanism for the Bardolino development is natural depletion. The 

development scheme requires a single subsea production well, which is planned to be drilled during Q2 

2009, targeting production from the Fulmar reservoir. The well will be tied-back to the Nelson 

platform via a single subsea 6” Production pipeline to the Howe PTS. From Nelson, oil will be 

exported into the Forties Pipeline System (FPS) to Grangemouth, and gas exported via the Fulmar Gas 

Line (FGL) to St Fergus. 

The Facilities Engineering scope includes: 

� 1 subsea production well, complete with subsea xmas tree, controls, cocoon “fishing friendly” 

wellhead protection structure;

� Manifold structure housing cooling spool, multiphase flowmeter, pigging/future tie-in points; 

� Tie-in spools and controls jumpers between well and manifold and between manifold and 

pipelines; 

� A 2km 6" production pipeline. The pipeline may be snake laid on the seabed, trenched and 

backfilled, or trenched or rock dumped. 

� A 2km 3-inch gaslift line piggybacked to 6" production line or laid and trenched independently. 

Multi-function umbilical will be provided for control, chemical injection and scale-treatment. 

� Tie-in spools between manifold / pipeline, and pipeline / riser at Howe; 

� Topsides modifications covering control system upgrades, chemical injection and storage 

facilities. 

As part of the project planning process, a full Environmental Impact Assessment is being carried out 

for this activity and once this is completed, we will be submitting an Environmental Statement for the 

development. In line with DTI regulations [The Offshore Petroleum Production and Pipe-lines (Assessment of 

Environmental Effects) Regulations 1999], the Environmental Statement will be available and open for 

public consultation as part of the approval process. 

In addition and as part of Shell’s commitment to Health, Safety and the Environment in the pursuit of 

the goal of no harm to people, protection of the environment and the efficient use of materials and 

energy, we intend to consult widely with all who may have an interest in our project activities and invite 

you for further dialogue, should you wish to take part in such consultations. 

If you would be interested, I would be grateful if you could complete the attached form and return it to 

Paul Wood at the above address, or by e-mail to Bill.Gray@shell.com by 27 th March. Please pass the 

form to anyone else in your organisation that might also be an appropriate contact for consultation. 

Yours sincerely 

Bill Gray 

Project Manager, Bardolino field development. 

2

To: 

Paul Wood 

Shell U.K Limited, 

Seafield House, 

Hill of Rubislaw, 

Anderson Drive, 

Aberdeen 

AB15 6BL 

I am interested / not interested in further dialogue around the proposed Bardolino field development 

in the central North Sea. 

I would like: (Tick as appropriate) 

i) An opportunity to raise issues/ concerns directly 

ii) To be kept informed of updates at key stages via email 

NAME ……………………………………………………………………………… 

ORGANISATION…………………………………………………………………. 

ADDRESS ………………………………………………………………………… 

TEL ………………………….. FAX …………………………………………… 

E-MAIL …………………………………………………………………………… 

My main areas of interest are: 

Environmental Impact Social Impact 

Safety Economic Impact 

3

Sustainable Development Technology 

Other (please specify) ……………………………………………………………. 

Signed ………………………………… Date ………………………. 

Data Protection Statement 

Your contact details are securely held by Shell U.K. Ltd and will be treated confidentially as part of our 

consultation process on the Bardolino field development project activity. 

4


APPENDIX 4 SHELL PILING PROCEDURE 

This Appendix presents a copy of Shell’s procedure for piling activities which will be followed 

during the Bardolino development. The procedure has been discussed and agreed with the 

JNCC. 

April 2008

GUIDELINES FOR MINIMISING ACOUSTIC DISTURBANCE TO MARINE 

MAMALS FROM PILING OPERATIONS 

JULY 2007 

These guidelines are aimed at minimising the risk of acoustic disturbance to marine 

mammals including seals, whales, dolphins and porpoises from piling operations. In 

addition to keeping noise levels at lowest practicable levels the recommendations 

contained in these guidelines should assist in ensuring that marine mammals in 

areas of proposed piling activity are protected against possible injury. These 

guidelines reflect a precautionary approach that should be used by Shell when 

planning marine piling operations that could cause acoustic or physical disturbance 

to marine mammals. 

Under the EC Habitats Directive (92/43/EEC) Annex IV(a) all cetaceans (whales, 

dolphins, porpoises, etc.) and seals are listed as European Protected Species (EPS). 

The Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 make 

it an offence to deliberately capture or disturb any Annex IV(a) species and states 

that; 

“The provisions apply to any of the listed species in any part of the UKCS, not just in 

protected areas. The impact of a plan or project on these species must be taken into 

account in deciding whether consent can be granted” 

These regulations can be interpreted as meaning that a failure to mitigate potential 

disturbance, injury or death to marine mammals is an offence. Although no formal 

guidelines currently exists for piling operations in the UK (as of July 2007), these 

guidelines have been developed with input from the Joint Nature Conservation 

Committee (JNCC) who have drawn upon their experience in formulating guidelines 

for use in the seismic industry. Therefore, these guidelines have been developed as 

best practice for Shell to follow during piling activities. 

Despite being written specifically for the operations within the UKCS these guidelines 

are considered particularly relevant for the Netherlands where the EU Habitats 

Directive is still being transposed in to national law. 

It should be noted that within the UKCS it is potentially controversial to use any form 

of Acoustic Deterrent Devices (ADDs), otherwise known as ‘pingers’, and it is 

strongly recommended that this be the case in both Dutch and Norwegian waters too. 

It should be noted that the deployment and use of Acoustic Deterrent Devices 

(ADDs) as a measure to prevent marine mammals approaching the area of activities 

is likely to constitute deliberate disturbance to marine mammal populations. Within 

territorial waters (12nm) their deployment would require a licence from Natural 

England (English Waters), Welsh Assembly Government (Welsh Waters) or Scottish 

Natural Heritage (Scottish Waters) and from August 21 2007, under the Offshore 

Marine Conservation (Natural Habitats etc) Regulations 2007 (SI 2007/1842), the 

Marine and Fisheries Agency for waters outwith territorial limits. 

We recommend that a copy of these guidelines are available onboard all vessels 

undertaking piling activities in the UKCS.

What risks to marine mammals do piling operations pose? 

Piling operations generate very high sound pressure levels and are relatively broadband 

(20 Hz - >20kHz; Nedwell and Howell 2004). Piling activities propagate sound 

through the water column, the air into water and to a lesser extent through the 

sediment, but how much of this noise propagation can marine mammals hear? 

Figure 1. shows four zones of noise influence as defined by Richardson et al. (1995) 

depending on the distance between the source and marine mammal. 

Figure 1. Zones of noise influence (Richardson et al. 1995). 

The zone of Audibility is the area within which the animal is able to detect sound. 

The zone of Responsiveness is the region in which an animal reacts behaviourally 

or physiologically. The zone of Masking is highly variable, usually somewhere 

between audibility and responsiveness and defines the region in which noise is 

strong enough to interfere with detection of other sounds, such as communication 

signals or echolocation clicks. Hearing loss is the zone where exposure to noise of 

sufficiently high intensity causes a reduction in hearing sensitivity (an upward shift in 

the threshold). This can be a temporary threshold shift (TTS), with recovery after 

minutes or hours, or a permanent threshold shift (PTS) with no recovery. PTS may 

result from chronic exposure to sound, and sounds that can cause TTS usually cause 

PTS if the subjects are exposed to them repeatedly and for long enough. However, 

very intense sounds can cause irreversible cellular damage and instantaneous PTS. 

What ‘noise’ are we concerned about? 

The most important consideration for piling activities is the sound level that is 

generated and subsequently received by an animal. The sound level can be 

described in a number of ways with the most common being the Sound Pressure 

Level (SPL), this is measured in decibels referenced to 1 microPascal (dB re1µPa). 

The SPL is based on an average of the pressure over a short period of time. When 

sound levels vary considerably over a short period of time, as occurs during hammer 

piling, where there are associated peaks in sound corresponding to when the 

hammer strikes, a more appropriate measurement will be the peak Sound Pressure

Level (SPL peak). This gives the maximum sound pressure level over an event or a 

short period of time. 

Piling operations can encompass a wide range of operations, piling equipment, 

substrate types, water depths etc which result in the generation of a wide range of 

possible noise source levels and associated transmission losses. 

There is little information available in the scientific literature relating to noise levels 

that cause injury to marine mammals making an assessment of the potential effects 

from piling activities difficult. However there are a few studies that link both noise 

levels and marine wildlife observations. There have also been specific studies 

identifying hearing ranges for specific species. The ranges for Harbour porpoises 

(Kastelein et al. 2002) and Harbour seals (Kastak & Schustermann, 1998) both of 

which are relatively common North Sea marine mammals are given in Table 1. 

Table 1. Hearing range and threshold for Harbour Porpoise and Harbour Seals. 

Sub Order/ Example Species Hearing range 

Species 

(kHz) 

Odontoceti Harbour porpoise 

< 1 

(Kastelein et al. 2002) 

1 – 8 

16 – 140 

Pinniped Harbour seal 

0.075 – 0.2 

(Kastak & Schustermann, 0.2 – 0.8 

1998) 

0.8 –1.6 

6.4 

Threshold 

(dBrms re 1µPa) 

92 – 115 

60 – 80 

32 – 46 

83.8 – 101.9 

38.9 – 83.9 

67.1 – 79.8 

62.8 

From the scientific literature, injury (PTS and TTS) is a concern when the received 

SPL exceeds 180 dBrms re 1µPa for cetaceans and 190 dBrms re 1µPa for seals 

(NMFS 2003). Therefore it is essential that these zones are taken into account 

during the planning phase of the piling operation and mitigation is developed. 

The aim of any piling mitigation is therefore to minimise the risk of PTS or TTS being 

caused. 

Environmental Assessment of the risks posed by piling operations to marine 

mammals. 

Depending on the scale of the piling operation a detailed environmental 

assessment should be submitted in either the project Environmental Statement 

(ES) or PON15c. It is recommended that the Project Manager should consult 

the project Environmental Advisor (EA) at the earliest possible opportunity to 

determine the scope of this environmental assessment. 

The environmental assessment will provide relevant stakeholders with information 

regarding the mitigation to be used to minimise the risk to marine mammals during 

the piling operation. Mitigation measures will be based on the scale of the operation 

in respect to the size/number of piles, duration and timing of the operation. Best 

practice for this environmental assessment would constitute the inclusion of the 

following information:

Noise propagation modelling. 

Noise modelling is a useful tool to apply when assessing the most appropriate 

mitigation to adopt. One method to model sound propagation is the source level – 

transmission loss model, where transmission loss is the rate at which sound 

attenuates with distance, By subtracting this model from the source level allows for 

the calculation of received sound levels with distance. The output of the model is 

best displayed as a map that illustrates the noise propagation contours generated 

from a source level. The sound model can identify distances at which the sound 

levels are expected to cause PTS and TTS and can be used in establishing the most 

appropriate size of Exclusion Zone for the Marine Mammal Observer (MMO) to 

monitor. 

The Exclusion Zone is defined as the area in which the MMO searches for marine 

mammals. For seismic surveys this zone is typically 500m, but for piling operations 

at offshore windfarms it has been increased to 1km. 

In order to mitigate against exposing cetaceans and seals to noise levels that can 

cause PTS and TTS, noise propagation modelling should be carried out. The output 

of this should be maps illustrating noise propagation contours moving away from the 

piling operation. These maps should identify the PTS/TTS zone around the piling 

operation at an SPL of 190 dBrms re 1µPa. 

Cetacean/seal distribution maps. 

The likelihood that marine mammals will be encountered in a given area should be 

discussed with the EA and by consulting suitable reference material such as The 

Atlas of Cetacean distribution in North-West European waters (Reid et al, 2003). 

Operations should be planned so that their timing will reduce the likelihood of 

encounters with marine mammals especially during the breeding and calving 

seasons. If an area is particularly sensitive, due to the species present, care should 

be taken to justify the timing of the operations. 

Marine Mammal Observer (MMO) requirement 

The project should seek to provide the most appropriately qualified and experienced 

personnel to act as MMOs. Project Managers are advised to contact their 

Environmental Advisor at the earliest opportunity regarding the need for MMOs. 

For particularly sensitive areas where there is a high probability of cetaceans being 

present the MMO must be an experienced cetacean biologist or an experienced 

MMO (i.e. an observer with at least three seasons worth of experience). In 

particularly sensitive areas two dedicated MMOs may be requested, the use of a 

crewmember with other responsibilities as the second observer is not considered an 

adequate substitute for a dedicated MMO. 

The MMO should be employed solely for the purpose of monitoring the 

implementation of the ‘soft start’ guidelines and visual observation of marine 

mammals during periods of active piling. The MMO should be located at the optimal 

vantage point aboard the source vessel (i.e. the HLV) and using binoculars. The 

MMO should be empowered to postpone operations and have direct communication 

with vessel captain and Shell representative.

For small scale piling operations where it is not deemed necessary to have a 

qualified MMO on board a Fisheries Liaison Officer (FLO) may be a suitable 

alternative depending on relevant experience. The project EA will be able to advise 

on MMO requirements. 

In addition to MMOs, but not instead of, the use of Passive Acoustic Monitoring 

(PAM) systems for acoustic detection of cetaceans is encouraged to increase 

detection capabilities. 

The Marine Mammal Observer (MMO) should adhere to the following Protocol 

during piling activities: 

1. Look and Listen 

Beginning at least 20 minutes before commencement of any use of the hammer, the 

dedicated MMO should carefully make a visual check from the optimum vantage 

point of the HLV to see if there are any marine mammals within the exclusion zone 

(as determined using the output from the noise propagation modelling). The MMO 

must have adequate visibility to see the full extent of the exclusion zone. 

After the watch for marine mammals have given the all clear to proceed with the 

piling operation it is recommended that a ‘soft start’ occurs. This is where the 

intensity and/or speed of the piling operation is slowly ramped up until the full piling 

intensity is reached. All piling operations should ensure that all ‘soft starts’ occur 

during daylight hours when MMOs can carry out the required 30 – 40 minute watch 

(20 minimum). Piling can begin in daylight and continue through in to darkness but 

piling cannot commence at night as this may be interpreted as ‘deliberate 

disturbance’. 

2. Delay 

If marine mammals are seen within the defined exclusion zone commencement of 

the piling operation should be delayed until they have moved away, allowing 

adequate time after the last sighting for the animals to move away (at least 20 

minutes). 

3. The ‘Soft Start’ 

Ensure that the correct ‘soft start’ procedure is followed. ‘Soft starts’ are intended as 

a time period to allow marine mammals to move away from an area should they wish 

to do so. 

Power should be built up slowly from a low energy start-up (e.g. starting with low 

pressure piling) over as long a period as is technically possible (please consult with 

the EA on this) to give adequate time for marine mammals to leave the vicinity. This 

build up of power should occur in uniform stages to provide a constant increase in 

output. There should be a ‘soft start’ every time the hammer is used, even if no 

marine mammals have been seen. 

Once the ‘soft start’ has commenced it is not required to stop even if marine 

mammals are subsequently observed.

If, for any reason, piling operations stop and not restarted for at least 5 minutes a full 

‘soft start’ should be carried out. After any break in piling of any duration a visual 

check should be made for marine mammals within the PTS/TTS zone. If a marine 

mammal is present then recommencement of piling should be delayed as per the 

Look & Listen, Delay and Soft Start instructions above. 

It is highly desirable that hydrophones be placed off a ‘quiet vessel’ to monitor the 

actual noise produced at various distances from the piling operation in order to 

ground truth the noise propagation models from the environmental assessment. 

Reporting compliance with guidelines: 

A report detailing marine mammals sighted and details of the piling operation, using 

the recording forms provided in Appendix 1, should be sent to the project EA who will 

forward it on to the JNCC. The report should include the following information along 

with the completed forms from Appendix 1: 

• Date and location of piling operation. 

• Number and size or piles. 

• A record of all occasions when piling occurred, including the watch 

beforehand and the duration of the ‘soft-start’. 

• Details of any problems encountered during marine mammal detection 

procedures, or during the survey. 

• Marine mammal sightings. 

• Details of watches made for marine mammals and the piling activity during 

watches. 

• Detections made with the PAM and any corroborating sightings. 

• If possible ‘ground truthed’ noise propagation models that are able to verify 

the noises estimated from the noise model. Such information will be of 

use in future developments. 

Legislative links: 

EC Habitats Directive (92/43/EEC) 

The Offshore Petroleum Activities (Conservation of habitats) Regulations (2001), 

Offshore Marine Conservation (Natural Habitats etc) Regulations 2007 (SI 

2007/1842).

References 

Kastak, D. and Schusterman, R.J. (1998). Low–frequency amphibious hearing in 

pinnipeds: methods, measurements, noise and ecology. J. Acoust. Soc. Am. 103, 

2216-2228. 

Kastelein, R.A., Bunskoek, P., Hagedoorn, M. and Au, W.W.L. (2002). Audiogram of 

a harbor porpoise (Phocoena phocoena) measured with narrow-band frequency 

modulated signals. J. Acoust. Soc. Am. 112, 334-344. 

Nedwell, J., Howell, D. (2004). A review of offshore windfarm related underwater 

noise sources. Tech. Rep. 544R0308, Prep. by. Subacoustech Ltd., Hampshire, UK, 

for: COWRIE. 

NMFS (2003). Taking marine mammals incidental to conducting oil and gas 

exploration activities in the Gulf of Mexico. Federal register 68, 9991-9996. 

Richardson, W.J., Greene, C.R.G. jr., Malme, C.I. and Thomson, D.H. (1995). 

Marine Mammals and Noise. Academic Press, San Diego, 576 pp. 

Reid, J.B., Evans, P.G.H., & Northridge, S.P., (2003), Atlas of Cetacean distribution 

in north-west European waters, 76 pages, colour photos, maps. Paperback, ISBN 1 

86107 550 2. 

Thomsen, F., Lüdemann, K., Kafemann, R. and Piper, W. (2006). Effects of offshore 

wind farm noise on marine mammals and fish. Biola, Hamburg, Germany on behalf 

of COWRIE Ltd.

APPPENDIX 1 

MARINE MAMMAL RECORDING FORM - RECORD OF SIGHTING 

Piling Operations 

Options in italics should be circled, ticked or underlined as appropriate 

Date 

Name of Contractor 

Name of Client 

Vessel's position 

(latitude and longitude) 

Time of sighting (GMT) 

Type of marine mammal detected (please tick box) 

Whale species [ ] 

Dolphin species [ ] 

Seal species [ ] 

Marine Mammal Observer 

UKCS Licence block Water depth (metres) 

Other (e.g. turtle, basking shark, please specify)………………………… 

Total number of animals 

Number of adults 

Number of juveniles 

Description (include features such as overall size; shape of head; colour and pattern; size, 

shape and position of dorsal fin; height, direction and shape of blow) 

Species (e.g. Bottlenose dolphin, Minke 

whale, grey seal) 

Animals Behaviour 

Piling activity when animals first observed (please 

tick) 

Before piling soft start [ ] 

During piling [ ] 

After piling ended [ ] 

Certainty of identification (please circle) 

Definite / Probable / Possible 

Return to: JNCC, Dunnet House, 7 Thistle Place, Aberdeen, AB10 1UZ 

(fax. 01224 621488; e-mail seismic@jncc.gov.uk). 

Closest distance of animals 

from piling source (metres) 

(Record even if not firing)

MARINE MAMMAL RECORDING FORM- PILING OPERATIONS 

Piling Contractor.................……..……… Client…………………………….. Marine Mammal Observer............................................................. 

Date……………………………………… UKCS License block:……………… 

Location of MMO (tick one): piling vessel [ ] guard/standby vessel [ ] 

Wind force and direction (use Beaufort scale 1-12, e.g. W5)……………………….. 

Visibility (Choose from:D=Dark, P = poor(< 1 km),M = moderate(1-5 km),G = good (> 5 km)…………… 

Sea state (Choose from:G = glassy (like mirror), S = slight (no or few white horses), C = choppy (many white horses), R = rough (large waves, foam crests, spray)…………………. 

Swell (Choose from:O = low (< 2 m)M = medium (2-4 m) L = large (> 4 m)………………………………… 

Method of soft start (tick one): Increase hammer Pressure [ ], Increase strike rate [ ], Not applicable [ ] 

Please record the following information even if no marine mammals are seen. 

Start of 

watch 

(GMT) 

Were marine mammals detected 

during the 30 minutes before 

piling started 

Yes/No 

Yes 

Delay soft start 

until no marine 

mammals 

detected for 20 

minutes. Fill in 

the record of 

sightings form. 

No 

Proceed with soft start 

Time piling 

started 

(time of soft start) 

(GMT) 

Time piling 

stopped 

(GMT) 

End of watch 

(GMT) 

Duration of watch for 

marine mammals 

(hrs & mins) 

Return to: JNCC, Dunnet House, 7 Thistle Place, Aberdeen, AB10 1UZ (fax. 01224 621488; e-mail seismic@jncc.gov.uk). 

Were any marine 

mammals detected during 

the watch 

Yes 

Fill in record of 

sighting form 

No 

No action

ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

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