PLANNING ACT 2008 

THE INFRASTRUCTURE PLANNING (EXAMINATION PROCEDURE) RULES 2010 

(“the 2010 Rules”) 

Application by SMartwind Ltd ( “the Applicant”)for an Order granting Development Consent (“the 

Order”)for the Hornsea Offshore Wind Farm – Project One( “the Project”)   

WRITTEN REPRESENTATIONS and RESPONSES TO FIRST ROUND WRITTEN QUESTIONS 

By PHILLIPS 66 LIMITED (“P66”) (registration identification number 10021269) 

Planning Inspectorate Reference Number: EN010033 

1. Introduction 

 

1.1. These written representations are submitted pursuant to rule 10 of the 2010 Rules and in 

accordance with the Examining Authority’s procedural decisions dated 18 December 2013. 

1.2.  P66 own and operate the Humber Refinery which sits on a 480‐acre site at South 

Killingholme on the Humber Estuary.  

1.3. The refinery imports crude oil via a tanker unloading buoy  linked by an 8.4 km subsea 

pipeline to oil storage tanks at Tetney, 16 miles south of the refinery, on the Lincolnshire 

coast. The pipeline is routed underground (under the sea bed, beach, salt marsh, sea 

defences and arable land) to the tank facility at Tetney. From Tetney the oil is pumped 

overground to smaller crude oil storage tanks at the refinery for processing. 

1.4. P66 have concerns in connection with the Project and how it is likely to impact upon the 

crude oil sea line (and the proposed replacement of part thereof) and land line (together 

“the Pipeline”). These concerns are dealt with in detail later in this Written Representation 

but briefly they relate to:‐ 

1.4.1. the proximity of the proposed high voltage cables to the Pipeline and the effect any 

normal running and /or fault conditions that  the cables may have to their  cathodic 

protection. 

1.4.2. how the proximity of the South West  offshore corridor to the Pipeline route  will affect 

the anchor pattern for workboats maintaining the Pipeline off‐shore  and possible 

interference with cathodic protection. 

1.4.3. interference both during the construction process for the installation of the power 

cables and after installation affecting maintenance access from Horseshoe Point to the 

Pipeline on the beach  

1.4.4. interference during the construction process for replacement of part of the Pipeline 

with a) construction access onto the beach near Horseshoe Point b) construction HGV 

access from Sheep Marsh Lane and alongside the airfield and c) construction access 

through Stonebridge farm. 

1.5. P66 is currently in discussions with the Applicant in connection with these matters and 

provided these concerns are addressed and satisfactorily resolved P66 will have no 

objection to the Application. 

1.6. Since submitting its Relevant Representation on 11 October 2013 P66 has continued to 

liaise with the Applicant in relation to the impacts of the Project upon the Pipeline. 

 

2. Proximity of the proposed high voltage cables to the Pipeline and the effect any normal 

running and /or fault conditions that  the cables may have to their cathodic protection 

2.1. P66 have prepared a report (RPT‐11‐577‐02 Rev 5) (attached at Appendix One) outlining the 

identified concerns, risks and potential costs associated with the proximity of the proposed 

cables to the Pipeline.  

P66 have been advised by the Applicant that there is at present, uncertainty over the 

method of transmission to be used. (HVDC or HVAC cable system). Each system presents its 

own set of possible risks and implications, documented in the report. 

Further technical detail regarding the power system to be used is required to enable a fully 

detailed assessment of the concerns and risks presented by the Project. 

This in turn will allow identification of issues to be addressed by any Proximity Agreement 

or protective provisions. 

2.2. The parties have agreed in principle to enter into a Proximity Agreement to manage the 

interface between the Project and the Pipeline. Negotiations have progressed but require 

further technical clarification to allow any agreement to be concluded. 

2.3. Therefore P66 registers a holding objection until such time as either an agreement is 

entered into or protective provisions satisfactory to P66 are agreed for inclusion in the DCO 

for the protection of the Pipeline.  

2.4. P66 will continue to cooperate with the Applicant. However in the absence of either an 

agreement being entered into or protective provisions agreed satisfactory to P66, P66 will 

maintain its objection and submits that the Secretary of State should not grant 

development consent. 

 

3. How the proximity of the South West offshore corridor to the Pipeline route will affect the 

anchor pattern for workboats maintaining the Pipeline off‐shore and possible interference 

with cathodic protection. 

3.1. P66 will require access to the Pipeline by their maintenance vessels at all times. Such 

vessels may require to position themselves over any offshore point on the Pipeline route, 

and to maintain this position using an anchor spread. Any such anchors may be required to 

be set up to the limits of the Pipeline 500m safety zone. 

3.2. P66 require that the Applicant avoids the necessity to lay anchors within the Pipeline 500m 

safety zone. In the event that the anchor configuration cannot be arranged to 

accommodate this requirement, P66 requires the Applicant to agree a works method 

statement before commencing any anchoring operations in the 500m safety zone. 

Such method statement shall be agreed jointly, both parties acting reasonably, and in 

accordance with HSE Document ‘Guidelines for Pipeline Operators on Pipeline Anchor 

Hazards’ 

3.3. Possible interference with cathodic protection has been identified as a potential concern. 

As stated in (2.1), further technical detail is required to assess whether the separation 

advised is adequate to preclude the concerns. 

 

4. Interference both during the construction process for the installation of the power cables and 

after installation affecting maintenance access from Horseshoe Point to the Pipeline on the 

beach  

 

4.1. P66 have land access agreements to cross the beach in the vicinity of the Applicants 

proposed Intertidal Order Limit Boundary. 

4.2. P66 would require maintenance access to cross this area from Horseshoe Point both during 

and after construction of the Project. Normal maintenance access is expected to be 2 light 

vehicles per month (up to 3 tonnes) 

4.3. P66 may, on occasion require maintenance access for larger vehicles (up to 6 tonnes). 

Therefore the Applicant should make arrangements to ensure the load bearing capability of 

the route is not compromised both during and after construction of the Project. 

Consideration should also be made to ensure headroom and track width is not 

compromised for vehicles of this size. 

 

5. Interference during the construction process for replacement of part of the Pipeline with a) 

construction access onto the beach near Horseshoe Point b) construction HGV access from 

Sheep Marsh Lane and alongside the airfield and c) construction access through Stonebridge 

farm. 

5.1. P66 Pipeline Replacement Scheme options are still under development, and there is 

potential for a requirement for access by larger construction traffic at a number of 

locations.  

5.1.1.  Construction access onto the beach near Horseshoe Point to the Pipeline on the 

beach. 

5.1.2.  Construction HGV access from Sheep Marsh Lane and alongside the airfield 

5.1.3.  Construction access through Stonebridge farm. 

5.2. P66 require consideration be made to ensure load bearing, headroom, track width and 

general access is not compromised in the locations outlined in 5.1 for vehicles of this size. 

5.3. A plan at Appendix Two delineates the possible routes and options. 

 

6. Protection regulatory framework 

6.1. P66 requires that relevant guidance in relation to safety clearances and work practices 

within the vicinity of its pipelines are complied with at all times. 

6.2. The Pipeline Safety Regulations 1996 require that pipelines are designed, constructed and 

operated so that the risks are as low as is reasonably practicable. In judging compliance 

with the Regulations, the HSE expects dutyholders to apply relevant good practice as a 

minimum. For new plant installations and situations, this will mean the application of 

current good practice. For existing plant installations and situations, this will mean the 

application of current good practice to the extent necessary to satisfy the relevant law. 

6.3. The following standards are relevant: 

6.3.1. Pipeline Safety Regulations  

http://www.legislation.gov.uk/uksi/1996/825/contents/made 

6.3.2. Guidance on anchor hazards for pipeline operators 

http://www.hse.gov.uk/pipelines/pipeline‐anchor‐hazards.pdf 

6.3.3. BS 7361‐1 Cathodic protection ‐ Part 1: Code of practice for land and marine 

applications. 

 

 

 

7. Compulsory Acquisition of Land 

7.1. P66 have the benefit of a number of easements permitting the retention of, access to and 

maintenance of the Pipeline.  

7.2. In order to protect the Pipeline P66 requires assurance that at all times it will continue to 

have sufficient rights of way over the Order land being acquired to access the Pipeline and 

maintain, repair and inspect the Pipeline. 

8. Protective provisions 

8.1. As drafted the proposed Order is at present deficient in that it does not contain protective 

provisions in the form required by P66 for the protection of its Pipeline. 

8.2. P66 maintain that without appropriate protective provisions there would be an 

unacceptable risk of damage to the Pipeline. Damage or failure of that apparatus may have 

serious hazardous consequences with respect to safety and integrity of apparatus and 

personal safety. 

 

9. First Round Written Questions 

9.1. P66 has been provided with a copy of the applicant’s response to the Examining Authority’s 

Rule 8 questions. 

9.2. P66 has commented on the Applicant’s response and the response forms the agreed view 

of the Applicant and P66 however subject to the matters dealt with in this Representation 

and as identified above the agreement of protective provisions satisfactory to P66. 

Phillips 66 Limited 

20 January 2014 

 

 

 

 

 

 

 

Appendix One  ‐ RPT‐11‐577‐02 Rev 5 

IACS Risk and Cost Report December 201

 

Appendix Two – Plan referred to at point 5.3 

 

IACS Corrosion Engineering Ltd

Review of the Stray Current Interference Risks and Costs from the Proposed HVDC and HVAC Transmission Systems on the 22” Pipeline

Phillips 66 Ltd December 2013

IACS Corrosion Engineering Ltd Building 500

Churchill Way Biggin Hill

Kent TN16 3BN

Report RPT-11-577-02 Rev 5

RPT-11-577-02 REV 5 Page 2 of 28

TABLE OF CONTENTS 1. Introduction ........................................................................... 4

1.1 Abbreviations 6

2. Reference Documents .......................................................... 7

2.1 Statutory Legislation 7

2.2 Relevant Standards 7

2.3 Relevant International Standards 7

2.4 IGE Standards 8

2.5 Fisher Germain Priestner Drawings 8

2.6 Relevant Publications 8

2.7 National Grid and Phillips 66 Ltd Codes 9

3. Pipeline Systems .................................................................. 9

4. Power Transmission Systems ........................................... 10

4.1 General 10

4.2 Powerline Route 10

4.3 Powerline Systems 10

4.4 HVDC Transmission 10

4.5 HVAC Transmission System 13

4.6 Touch and Step Potential Risks 15

5. Stray Current Interference ................................................. 15

5.1 General 15

5.2 DC Systems 15

5.3 AC Systems 16

5.4 AC Interference Risk Existing Powerlines 17

5.5 Design Risks 17

6. Pre Construction Activities and Costs HVDC Transmission Systems ............................................................. 18

6.1 General 18

6.2 CIP and DCVG Surveys 18

6.3 Pipeline Location and Depth Surveys 19

6.4 Pipeline CP System 19

6.5 Intelligent PIG Survey 20

6.6 Mathematical Modelling 20

6.7 6” Condensate Pipeline 21

6.8 HVDC Substations 21

6.9 DC Interaction SMart Wind Cables 21

7. Pre Construction Activities and Costs HVAC Transmission ............................................................................. 21

7.1 General 21

7.2 CIP and DCVG Surveys 22

7.3 Pipeline Location and Depth Surveys 23

7.4 Pipeline CP System 23

7.5 Intelligent PIG Survey 23

7.6 Mathematical Modelling 24

RPT-11-577-02 REV 5 Page 3 of 28

8. Discussions ......................................................................... 24

8.1 Third Party Pipelines 24

8.2 Construction Methods 24

8.3 Notification of Fault 25

8.4 Philips 66 Ltd Management 25

8.5 Wayleave Agreements 25

9. Conclusions ........................................................................ 26

9.1 Summary of Technical Issues 26

9.2 Summary of Costs 26

10. Recommendations .............................................................. 28

Appendix A: Budget Cost Summary ................................................................... 1

Appendix B: Risk Summary Table ...................................................................... 1

REVISION AND AUTHORISATION RECORD

Rev Date Description Prepared By Checked By Approved By

A 19.04.2013 Internal Review P Lydon P Lydon M Andrew

0 22.04.2013 Issued to Client P Lydon M Andrew P Lydon

1 26.04.2013 Minor Changes to Recommendations

P Lydon M Andrew P Lydon

2 01.06.2013 Client Amendments Action P Lydon M Andrew P Lydon

3 15.07.2013 Ownership of Line

Amended P Lydon M Andrew P Lydon

4 30.07.2013 Ownership of Line

Amended C.Drakes M Andrew P Lydon

5 10.09.2013 Revised based Upon Client

Comments P Lydon C Drakes P Lydon

RPT-11-577-02 REV 5 Page 4 of 28

1. Introduction

IACS Corrosion Engineering Ltd was instructed by ConocoPhillips Ltd under cover of their order number 4515435948 dated 17

th June 2011 to provide technical assistance on the possible risks to the

ConocoPhillips Ltd 22” crude oil and ConocoPhillips (UK) Ltd 6” condensate pipelines from a HVDC

transmission system that SMart Wind proposed to install in the vicinity of the pipeline systems. The plans for a new high voltage direct current (HVDC) transmission line at that time were being considered by SMart Wind Ltd as part of the infrastructure required for development of the Hornsea offshore wind farm. The details of the method of operation of HVDC transmission systems, various risks to the pipeline system and possible costs associated with the construction and operation of the proposed HVDC transmission system had been summarised in IACS Corrosion Engineering Ltd report RPT-11-577-01 Rev 0, which was issued in August 2011. This report RPT-11-577-02 provides updated cost information on the risks and considers the implications of using either a HVDC or HVAC transmission system on the integrity of the Phillips 66 Ltd 22” crude oil pipeline. The changes to report RPT-11-577-01 were necessitated by the fact that SMart Wind is now not certain whether the power transmission system will be a HVDC or HVAC cable system and had requested that Phillips 66 Ltd update report RPT-11-577-01 Rev 0 to provide information on the latest costs for either power transmission system. This report also reviews the different risks to the pipeline system associated with both HVDC and HVAC power transmissions systems. The 22” crude oil pipeline is owned by COTH (Crude Oil Terminals (Humber) Limited) although the pipeline is operated by Phillips 66 Limited ( formerly known as ConocoPhillips Ltd). The owner of the 6” condensate pipeline is ConocoPhillips (UK) Ltd. Report RPT-11-577-01 considered the implications of the proposed HVDC cable transmission system on the 22” crude oil pipeline and 6” gas condensate pipeline. However, this report primarily concentrates on the effects on the 22” crude oil pipeline, since the 6” condensate pipeline is owned and operated by a different pipeline operator.

The HVDC/HVAC transmission system route that is now proposed by SMart Wind does not cross the 22” crude oil pipeline but there is one proposed crossing of the 6” condensate pipeline close to Tetney. There are however sections of the proposed HVDC/HVAC cable routes which run parallel and in close proximity to the 22” crude oil and 6” gas condensate pipelines. The transmission system cables it is understood are proposed to be buried along their entire route but only indicative typical details of their construction have been provided by SMart Wind at this stage.

At the time this report was written only outline details of the electrical specification for the HVDC or HVAC transmission system have been provided by SMart Wind. The details are summarised in Section 4.0 of this report. The implications of the proposed HVDC power transmission system on the 22” crude oil pipeline are the risk of stray current interference and corrosion on the pipeline due to stray current leakage, together with the increased safety risk to personnel and the general public in the event of power line to earth faults on the buried cable system or changes in the power line operating configuration. The implications of the proposed HVAC transmission system are the risk of AC corrosion on the pipeline due to inductive coupling and the increased safety risk to personnel and the general public in the event of electrical faults on the buried cable system. The purpose of this report is to provide outline information on the risks of corrosion on Phillips 66 Ltd’s asset and personnel safety due to electrical interference from either of the power cable transmission systems.

This document briefly summarizes the possible risks to the Philips 66 Ltd pipeline system, the likely impacts of the transmission system on the 22” crude oil pipeline and possible consequences that the operator Phillips 66 Ltd may experience as a result of the project particularly in relation to cost.

RPT-11-577-02 REV 5 Page 5 of 28

A summary of indicative budget costs for various pre-construction and post construction activities associated with the installation and operation of the HVDC or HVAC power transmission system that may affect the pipeline system is given in Appendix A.

It should be stressed that the costs given at this stage must be considered as purely indicative values to provide an estimate to Phillips 66 Ltd of the possible magnitude of costs that they may incur should the project proceed. The actual costs could vary by a significant extent from those identified in this report, which should at this stage be considered as ball park costs.

There will be ongoing costs to Phillips 66 Ltd for legal fees, management time and for the provision of specialist services that would need to be considered for the future. IACS Corrosion Engineering Ltd does not have any indication as to the likely magnitude of legal fees or land agents fees and the costs for such fees should be added as an extra to the costs identified in this report. This report specifically excludes information on the cost of legal fees, land agent fees and Phillips 66 Ltd management costs.

The precise effect that the HVDC system will have on the pipeline system is difficult to estimate at this stage, since there is limited information on the system configuration. It will not be until the HVDC system is energized that the precise nature of the interference that the 22” pipeline is subjected to would be able to be fully determined.

There are a limited number of onshore HVDC systems in the UK with similar configurations to that proposed for the project under discussion to know precisely what the extent of likely stray current interference will be. The system proposed by SMart Wind appears to be unique in terms of cross country buried cables within the UK as most systems tend to use overhead cables or sea based systems. SMart Wind should be requested to advise any details of similar systems so that pipeline operators that may have been affected can be contracted to ascertain the nature of any problems that they have experienced.

The precise location of any offshore HVDC substation would need to be identified by SMart Wind. The route of the HVDC cables may impact on Phillips 66 Ltd’s offshore pipelines near Tetney and a separate assessment of any risks undertaken once details of the offshore cable route have been advised.

It should be noted that it is considered for the purposes of this discussion that the HVDC system is a bipolar system as that is the indicative system proposed by SMart Wind. If there is DC current leakage it could cause significant corrosion problems on adjacent associated buried pipeline systems. SMart Wind would be recommended to address all these risks.

HVAC transmission systems also cause AC interference on buried pipeline systems. Guidance on the effect of HVAC systems on cathodically protected pipelines is given in BS EN 15280 and BS EN 50443. However, it should be noted that the latter standards primarily apply to overhead not buried power transmission systems.

Where HVAC power lines parallel buried pipelines they are generally routed overhead and this can result in both short and long term interference due to inductive and resistive coupling, which in some cases can have detrimental effects on buried pipeline systems. In the case of buried HV cable systems the level of induced AC voltage from inductive coupling is generally lower than in the case of an overhead power line system. It must be stressed that the costs given in this report are purely provisional at this stage. Once a precise scope of work has been agreed then more accurate costs can be provided.

The provisional costs identified in this report are dominated by the costs for pigging operations and the frequency of such operations and associated costs for pigging operations will need to be agreed by all parties. A summary of the main risks to the pipeline system from the proposed power transmission system is given in Appendix B of this report.

RPT-11-577-02 REV 5 Page 6 of 28

1.1 Abbreviations

The following definitions and abbreviations have been used in this document.

A Amps AC Alternating Current AWA Anglian Water Authority BS British Standard BT British Telecom CDM Construction (Design and Management) CEN Committee European Norm CHP Combined Heat and Power CIP Close Interval Potential CoP ConocoPhillips CP Cathodic Protection CSC Current Source Converter DC Direct Current DCVG Direct Current Voltage Gradient DFT Dry Film Thickness EN European Norm ER Electrical Resistance GW Gigawatt HDD Horizontal Directional Drill HOR Humber Oil Refinery HSE Health and Safety Executive HV High Voltage HVAC High Voltage Alternating Current HVDC High Voltage Direct Current IACS Inspection And Consultancy Services ICCP Impressed Current Cathodic Protection ICHP Immingham Combined Heat and Power IET Institute of Electrical Technology IGE Institute of Gas Engineers IF Insulated Flange IJ Isolation Joint ISO International Organisation for Standardization Kg Kilogram Km Kilometre LOR Lindsey Oil Refinery M Metre mV mV MW Megawatt NACE National Association of Corrosion Engineers NG National Grid NDT Non Destructive Testing NTS National Transmission System PIG Pipeline Internal Gauge RBI Risk Based Inspection RP Recommended Practice TR Transformer Rectifier V Volts VSC Voltage Source Converter

RPT-11-577-02 REV 5 Page 7 of 28

2. Reference Documents

2.1 Statutory Legislation

Health and Safety at Work Act 1974 The Environmental Protection Act 1990 The Groundwater Protection Code 2002 The Groundwater Regulations 1998 The Construction (Design and Management) Regulations 2007 The Electricity at Work Act Regulations 1989 Control of Substances Hazardous to Health Regulations 2002 Reporting of injuries. Diseases and Dangerous Occurrences Regulations

1995

Pipelines Safety Regulations 1996 Pressure System Safety Regulations 2000

2.2 Relevant Standards

The following standards are relevant to the subject under discussion in this report.

British Standards Title

BS 7340 Code of Practice Earthing BS 7361 : Pt 1 Cathodic Protection : Part 1 Code of Practice for Land and

Marine Applications BS 7671: 2008

Requirements for Electrical Installations. IET Wiring Regulations Seventeenth Edition

BS EN 12954 Cathodic Protection of buried or immersed metallic structures – General principles and Application for pipelines

BS EN 13509 Cathodic Protection Measurement Techniques BS EN 15280 Evaluation of a.c. corrosion likelihood of buried pipelines

applicable to cathodically protected pipelines BS EN 50162 Protection Against Corrosion By Stray Current from DC

Systems BS EN 50443 Effects of electromagnetic interference on pipelines

caused by high voltage a.c. electric traction systems and/or high voltage a.c. power supply systems

2.3 Relevant International Standards

The following standards are relevant to the cathodic protection system design and stray current interference.

International Standard Title

NACE SP 0177 -2007 Standard Recommended Practice - Mitigation of Alternating

Current and Lightning Effects on Metallic Structures and Corrosion Control Systems

RPT-11-577-02 REV 5 Page 8 of 28

2.4 IGE Standards

The following IGE standard is relevant to the subject under discussion.

Standard Number

Title

IGE/SR/28 Trenchless Crossing Techniques

2.5 Fisher Germain Priestner Drawings

The following drawings detail the proposed power line route. There has been no revision number stated on the drawings.

Drawing No. Drawing Title

S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 1 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 2 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 3 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 4 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 5 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 6 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 7 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 8 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 9 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 10 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 11 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 12 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 13 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 14 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 15 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 16 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 17 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 18 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 19 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 20 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 21 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 22 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 23 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 24 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 25 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 26 of 27 S005\P66-20130123 Dual Cable Routes and P 66 Utilities Plan 27 of 27

2.6 Relevant Publications

The following publications are relevant to this report.

Author Title

P Nicholson Paper 10102 Corrosion 2010 High Voltage Direct Current Interference on

Underwater and Underground Pipelines

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2.7 National Grid and Phillips 66 Ltd Codes

The following codes of practice for work in the vicinity of pipelines are relevant to the subject under discussion.

Standard Number

Title

T/SP/SSW/22 National Grid Specification for safe working in the vicinity of national grid high pressure gas pipelines and associated installations - requirements for third parties

Not Known

Phillips 66 Ltd Code of Practice for Safe Working in the Vicinity of Phillips 66 Ltd Pipelines

3. Pipeline Systems

The pipeline system primarily discussed in this report is the 22” crude oil pipeline from Tetney Tank Farm to the South Tank Farm at Phillips 66 Ltd’s Humber Refinery. The 22” pipeline is owned and operated by Phillips 66 Ltd and runs for most of its length in a common pipeline corridor with a 6” gas condensate pipeline owned and operated by Conoco Phillips (UK) Ltd. The effects on the 6” condensate pipeline by the new power transmission system are not discussed in any detail in this report. The pipeline details are as follows;

a) 22” crude oil pipeline design pressure 43.4 bar, length 22.8km, pipe material API 5L grade X42, 6.35mm minimum wall thickness, coating coal tar enamel date of construction 1969, operator and owner Phillips 66 Ltd

Anglian Water Authority also has pipelines that cross the 22” crude oil and 6” condensate pipelines. The precise number and size of these pipelines is not known by the author of this report. However, it is known that they are bonded into the 6” and 22” by a direct bond and thus there is an electrical connection between the AWA pipelines, the Phillips 66 Ltd 22” crude oil pipeline and the ConocoPhillips Ltd 6” gas condensate pipeline. The 22” crude oil pipeline and 6” gas condensate pipeline are electrically connected by direct bond cables and have a common CP system.

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4. Power Transmission Systems

4.1 General

It is understood that the precise nature of the electrical operating system that will be installed by SMart Wind for the power transmission system cannot be confirmed by SMart Wind at this stage. Phillips 66 Ltd has been advised that all power transmission cables will be buried and that either a HVDC system of HVAC system will be utilised. The information that Phillips 66 Ltd has at the time this report was issued on the possible power cable transmission systems is summarised in Sections 4.4 and 4.5 of this report and has been extracted from a PowerPoint presentation provided by SMart Wind to Phillips 66 Ltd in August 2012.

4.2 Powerline Route

The proposed route of the HVDC or HVAC power lines is shown on the drawings referenced in Section 2.5 of this report. There is one proposed power line crossing of the 6” gas condensate pipeline near Tetney shown on drawing plan 5 of 27. There are no proposed crossings of the 22” crude oil pipeline but there is a considerable length of parallelism of the power transmission cables with the 22” crude oil pipeline. The power line route runs parallel with the pipeline route for approximately 18 km with the minimum separation between the power line and the pipeline wayleave being 23m at Tetney. There is a 4km length of parallelism where the separation between the pipeline and power line working width is in the region of 50m. It should be noted that the 6” condensate pipeline is closest to the power lines and there is a 20ft (6m) separation between the 6” and 22” pipelines. Close to Killingholme at Habrough Rd the power cables cross the ICHP Ltd 24” high gas pipeline as shown on plan 23 of 27 at 3 locations.

4.3 Powerline Systems

It is understood that the development of the power transmission system is being handled by SMart Wind Ltd. However, it is also understood that when the project proceeds there will be two independent power line operators one for each of the two separate systems. Two circuits will be operated by Heron Wind Ltd and the other two by Optimus Wind Ltd. The Optimus Wind Ltd cable system will be the one closest to the 22” pipeline. Thus, there will be 4 separate systems. When reference to any indemnity is made in this report Phillips 66 Ltd would need to establish if a separate indemnity with each power line operator is required.

4.4 HVDC Transmission

The HVDC transmission system is believed to consist of buried cables for the onshore section of the power transmission system and subsea cables for the offshore section. It is understood that the section of the proposed power line in question consists of 4 separate bipolar systems each consisting of two buried cables. Two of the cable systems will be operated by Optimus Wind Ltd and two by Heron Wind Ltd. A total of 8 off cables will be provided.

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With regards to stray current interference from HVDC lines, the most important distinction to make is between monopolar and bipolar systems. In a monopolar configuration the converters are linked by a single pole line, with the ground being used to return current. This presents a considerably high risk of stray current interference on nearby metallic structures, particularly pipelines. Monopolar systems are most commonly used for systems where power can be transported through the water and the general mass of earth is used as the return conductor, as in the link between the North and South Islands in New Zealand. The circuit arrangement that has been identified by SMart Wind in information they have provided to Philips 66 Ltd indicates that a bipolar system will be installed. Bipolar configurations are less prone to stray current interference because the addition of a second line with an opposite potential, which theoretically reduces the ground current to zero. In practice, an imbalance in current loading between the lines is to be expected, which results in ground currents of the order of 1% line current. It is generally considered that in the region of 1% of the line current would be the possible leakage current although Phillips 66 Ltd in the US have indicated that it could be up to 2% . The precise value of leakage current would need to be confirmed by SMart Wind. However, 1% of the likely line current advised by SMart Wind would indicate a leakage current in the region of 15.6 Amps for 1 GW per circuit, this leakage may increase at higher power loadings and will depend upon the number of circuits in operation and the total current flow. For each of the four proposed cables, this would constitute a maximum current of approximately 1560A per cable per GW for a 400kV system operating +/- 400kV. This is based upon information provided by SMart Wind The HVDC configuration advised by SMart Wind is +/- 400 kV and details are given on Figure 1.

Figure 1 HVDC Power Source Information Advised by SMart Wind

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In the event of a single line failure on a bipolar system, the remaining line can continue to transmit power, operating as a monopolar system with the earth return. The ground current therefore undergoes an almost immediate hundred-fold increase. For this reason, it is vital that HVDC line operators liaise with neighbouring pipeline operators on the frequency and duration of line failures and those situations are avoided. Any indemnity would need to specify this. It would also be essential that the period of time that any monopolar operation exists for is limited. It is important for information to be provided on likely levels of induced voltages on the pipelines during fault situations and for the magnitude and duration of any fault would need to be advised by SMart Wind at the design phase. High DC fault currents can result in significant levels of corrosion in a relatively short period of time even a few hundred milliseconds. They can also induce hazardous voltages onto the pipeline system and these can represent a safety hazard to personnel working on the pipeline system or the general public if they have access to above ground appurtenances. SMart Wind has advised Philips 66 Ltd in their presentation in August 2012 that they will conduct earthing and ground potential rise (GPR) studies as part of their work. This report includes an indicative figure for such studies in the Phillips 66 Ltd list of costs at this stage. However, should the studies be paid for by SMart Wind, which would seem sensible then the figure can be removed from the list of costs given in Appendix A. SMart Wind has provided details of the cable construction, which for reference has been included as Figure 2 in this report. Details of the individual trench construction for the HVDC option are given on Figure 3

Figure 2 HVDC Power Source Route Cross Section Advised by SMart Wind

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Figure 3 HVDC Power Source Trench Cross Section Advised by SMart Wind

The magnitude of the DC leakage current is going to determine the extent of the stray current interference and if it is decided by SMart Wind to use a HVDC system discussions with SMart Wind would need to be carried out at an early stage to see how the DC leakage current can be limited. If it is too high then it may preclude the use of a HVDC system altogether. The magnitude of the DC leakage current could pose a significant problem for SMart Wind. It could damage pipeline systems close to the DC/AC converter stations. If the DC leakage current was high then it could limit the number of GW that could be transmitted by the HVDC transmission system and seriously jeopardise the integrity of the E ON Kinetica pipeline close to the HVDC substation. It would be essential that SMart Wind establish at an early stage, what the magnitude of DC leakage current is likely to be. If a 4GW system is proposed then based upon a value of 1% for the leakage current 60A could flow through the general mass of earth. At such a high current level significant levels of DC interference could be anticipated and may result in significant problems such that the HVDC system may need to be isolated. SMart Wind would be recommended to conduct their own assessment of the risks of DC interference.

4.5 HVAC Transmission System

HVAC lines are typically used to link alternating current (AC) power grids but most AC power lines are routed overhead and not buried. In this case the proposed AC transmission system is based upon a buried 220 kV HVAC system. The details of the HVAC system proposed by SMart Wind are shown on Figure 4

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Figure 4

HVAC Power System Advised by SMart Wind

The HVAC trench cross section has been advised by SMart Wind as complying with the information provided on Figure 5 and the trench construction with the information provided on Figure 6.

Figure 5

HVAC Power Source Route Cross Section Advised by SMart Wind

Figure 6

HVAC Power Source Trench Cross Section Advised by SMart Wind

Any earth conductor that is routed in parallel with the HVAC conductors would need to be insulated to mitigate localised potential gradients.

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4.6 Touch and Step Potential Risks

During fault situations on overhead and buried DC/AC power line systems hazardous touch and step potential voltages can be created. These fault situations would be relatively rare events and should occur for only a short duration of time until the circuit protection operates. However, during fault conditions there is a risk of a hazardous voltage being induced on the 22” pipeline and any pipeline systems electrically connected to it. This could be a risk to Phillips 66 Ltd and other pipeline operator personnel plus members of the public. Any assessment of the touch and step potential risks on the pipeline system and in the vicinity of the pipeline system would need to be conducted and suitable risk mitigation measures implemented.

5. Stray Current Interference

5.1 General

The nature of the electrical interference that may be experienced on a pipeline system from the HV power transmission systems is dependent upon the power line transmission system operating voltage, and current, the nature of the system i.e. whether AC or DC and whether the power line transmission system is overhead or buried. There are also a number of other factors that need to be considered. The effect various power systems can have on buried pipeline systems is discussed in the following sections.

5.2 DC Systems

HVDC transmission systems can cause stray current interference on buried metallic structures and limited guidance on this risk is given in BS EN 50162. A paper by Nicholson referenced in Section 2.6 of this report describes the problems that had been experienced on a pipeline system in Canada from HVDC transmission systems. The latter paper clearly demonstrates that stray current interference from HVDC systems is a known phenomenon. Whenever there is current flow in the earth, from whatever source, a piece of metal buried in the earth may function as a part of the current path, collecting current over a part of its surface and discharging it – with attendant corrosion – from another part. This may be illustrated by the case of a HVDC transmission system by current leakage from the HVDC substation earth during normal operating conditions, changes in operational configuration or during faults on the HVDC system. A proportion of the DC leakage current can return to the DC power source through the general mass of earth and some of that current can flow along buried pipeline systems as they would represent a low resistance path for the flow of current to the power source. In the case of HVDC transmission systems the total current flowing in the buried power conductors can be in the region of a few thousand amps. SMart Wind has indicated that for each GW the DC current flow would be 1560A, which at 1% leakage would equate to a current of 15.6A per GW. This could result in significant levels of DC stray current interference on buried pipeline systems.

. If stray current is produced the stray current can cause changes in the pipeline to soil potential changes at the current discharge point, which tend to produce an anodic condition, which will result in corrosion and need to be controlled.

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Thus, the pipeline may corrode over time if subjected to significant levels of interference. No corrosion should be experienced on the pipeline where current enters the pipeline as the pipeline will be cathodically protected at that location, as current would generally enter the line at this point. However, where current leaves the pipeline system to return to the power source an anodic condition will be experienced and corrosion will occur. It should however be noted that if excess levels of current enter a pipeline at a given location then this can result in high negative pipe to soil potentials and can cause cathodic disbondment, which could lead to detachment of the pipeline coating and corrosion of the pipeline under the disbonded coating. Thus, current entering a pipeline system can also result in problems. The greater the magnitude of DC current leakage the greater will be the extent of corrosion on the pipeline system. 1 Amp of current leaking off a pipeline over a year will result in a metal loss of 9 kg. Expressed as corrosion rate (average penetration of the steel surface) an anodic current density Jdc of 1 A/m² will result in a corrosion rate of 1.1 mm per year. Thus, if the DC current density leaving the steel surface is 1 Am

-2 this would equate to corrosion rate of 1.1mm per year. However, if the DC

leakage current was 10 Am-2

the corrosion rate would be 11 mm per year. This is the average corrosion rate and not the pitting rate, which would be higher. This corrosion, caused by a current originating from an external DC current source, is known as stray current corrosion. If that metal loss due to current discharge occurred over a relatively small area it could result in rapid rates of corrosion or even perforation of a pipeline system. This is the main cause of concern for the Phillips 66 Ltd pipeline i.e. current leakage could result in corrosion at relatively high

rates on the Phillips 66 Ltd 22” pipeline system.

5.3 AC Systems

HVAC transmission systems can cause AC interference on buried metallic structures and guidance on this risk is given in BS EN 15280 and BS EN 50443. Induced AC voltages due to long term interference can result in AC corrosion on cathodically protected pipelines, affect instrumentation and also represent in certain circumstances a safety risk. Although it had been demonstrated in the 1960’s that under laboratory conditions AC can cause corrosion of cathodically protected steel it was not recognised until comparatively recently in the UK that AC corrosion of cathodically protected pipelines can and does occur. AC corrosion occurs at small coating holidays on well coated pipelines where the pipeline suffers from induced AC voltages. Pipelines which parallel overhead power lines can have AC voltages induced on them. The AC current flow in the power line conductors produces an alternating magnetic field. Thus, an AC potential can be induced in an adjacent structure within that magnetic field and a current may flow in that structure. The magnitude of this induced potential depends on many factors including:

• The configuration of the power line and pipeline e.g. length of parallelism.

• The current load on the power line.

• In balance between phases.

• The dielectric strength of the pipeline coating.

• The soil resistivity.

In general terms the greater the current load on the power line, the longer the parallelism, the closer the proximity, the better the coating quality on the pipeline, the more likely it is that significant AC potentials will be induced on the pipeline.

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For many years, the general view in the corrosion industry has been that alternating current causes 1% of the corrosion of the equivalent direct current. The guidance given in BS EN 15280 is that no corrosion occurs at AC densities <30 A/m

2. However,

corrosion rates greater than 0.1 mmy-1

can occur at AC densities > 30 Am-2

.

For AC densities ≥ 30 Am-2

the protective potential criteria usually used for cathodic protection do not apply and AC corrosion is possible. The highest reported AC corrosion rate on a pipeline in the UK is 2.5mm per year. Standards on induced voltages from AC power lines generally relate to AC interference from overhead cables. However, in the case under discussion the cable system is buried and the nature of construction of buried cables means the level of interference is generally a lot lower than in the case of overhead cables. It should be noted that the HVAC cable construction proposed and detailed in Section 4.5 of this report, where 4 cable systems each separated by about 5m, could mean that the levels of induced voltage would be higher than would be the case in other buried cable configurations. Nevertheless, it should still be lower than the interference that would be experienced if an overhead power system was to be utilized. Mathematical modeling would be required to determine the levels of induced AC voltage on the 22” pipeline. It is important to note that that there is already AC interference on the 22” pipeline at Healing where the AC voltage sometimes exceeds or approaches the maximum permissible value of 4V. As is the case with DC systems the maximum voltage that would be induced on the pipeline during fault conditions will need to be established. SMart Wind has stated that they will undertake mathematical modelling to determine the GPR in the event of a fault. This will be particularly important close to the substations and at the intermediate cable junction and earthing pits. The mathematical modelling would need to look at short term and longer term interference levels and different operating scenarios. It would be important to note that the AC corrosion risk can be mitigated but this would mean the installation of supplementary earthing on the pipeline. The costs for which would be dependent upon the extent of earthing required.

5.4 AC Interference Risk Existing Powerlines

SMart Wind intends to provide a number of GW of additional power either from a HVDC or HVAC system. This additional power would be added to the existing overhead power cable system. IACS Corrosion Engineering Ltd does not have details on the power loading on the overhead transmission cables in the area. However, the additional [power generated by the Hornsea offshore wind farm would need to transmitted onto the existing NG infrastructure. Since the power load on a single circuit is generally limited to 1380MW unless a derogation is obtained to increase the power loading. The additional power load could change the current loading on the existing overhead circuits and thus could cause problems with increased levels of AC interference on existing buried pipelines. Thus, even if a HVDC power system was used when that power is converted to AC and then transmitted onto the grid then the AC interference on buried pipelines would be increased. This effect also needs to be considered as part of any modeling studies i.e. the additional AC interference risk from the additional current on the existing overhead cables.

5.5 Design Risks

All the risks to the 22” pipeline, Phillips 66 Ltd personnel and the general public will need to be addressed by SMart Wind in their design and CDM Safety File and would need to be mitigated against.

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The risks would include personnel safety, public safety and pipeline integrity. The consequences of failure of the pipeline system particularly safety and environmental would also need to be addressed. The touch and step potential voltages could affect the safety of Phillips 66 Ltd personnel and the risk of hazardous short term voltages could limit work on the pipeline system. Detailed mathematical modelling will need to be carried out to assess and determine the level of risk to the Phillips 66 Ltd pipelines and personnel. It should also be noted that mathematical modelling is not a precise science and that even though a model may predict certain earthing requirements for pipeline systems. In practice monitoring may well reveal that additional mitigation measures and hence costs may be warranted. Thus there are a number of risks. It should be noted that there are a number of pipeline operators and utility owners that would need to be consulted at the project planning stage these include Lindsey Oil Refinery, Network Rail, other pipeline operators, BT and electricity utility companies. Phillips 66 Ltd should be consulted on any risk assessment and review of risks undertaken by SMart Wind.

6. Pre Construction Activities and Costs HVDC Transmission Systems

6.1 General

The following sections describe some of the issues and activities that will need to be considered by Phillips 66 Ltd and SMart Wind as a result of the proposed project, if a HVDC transmission system was utilised. The costs that Phillips 66 Ltd may incur are outlined in Appendix A. It is to be stressed that some of the activities described may not be required and that the costs provided are indicative values only at this stage. The costs do not include any costs that Phillips 66 Ltd may incur for their additional management of the 22” pipeline system and Phillips 66 Ltd would need to add their management and legal costs to the costs identified in this report. There would also be extra ongoing operating and inspection costs associated with the HVDC transmission system. Thus, the annual monitoring and inspection cost to Phillips 66 Ltd would also need to be considered. The costs in Appendix A are only from design through to 1

st year of operation for both the HVDC and HVAC systems. There would be an annual

level of additional expenditure that Phillips 66 Ltd may incur, which would also need to be considered in the overall costs. SMart Wind has provided indicative technical information at this stage and this report may need to be amended when additional detailed information is provided.

6.2 CIP and DCVG Surveys

The existing 22” and 6” pipelines are not subject to DC stray current interference at present and if the SMart Wind project does proceed there is a strong possibility that the pipelines will be subjected to DC stray current interference in the future. The 22” crude and 6” condensate pipelines are electrically connected and any interference on one will be transferred to the other and vice versa. CIP and DCVG surveys are generally conducted at the frequencies required by Phillips 66 Ltd based upon RBI without any difficulties. The CIP surveys are normally conducted every 10 years and DCVG surveys are generally only conducted to identify pigging defects or coating defects identified by any CIP survey.

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However, If a pipeline is subject to DC stray current interference then conventional over the line pipeline surveys such as CIP and DCVG surveys may not be able to be conducted as easily in future, as they would in the absence of stray current interference. Indeed, data interpretation from CIP and DCVG surveys on pipelines that are susceptible to DC interference is problematical and can sometimes be of limited value. As a consequence a CIP and DCVG survey will need to be conducted prior to energisation of the HVDC system. This is because it may not be possible to conduct such a survey in future. A DCVG survey will be able to identify coating defects on the pipeline system. These will be locations where there is the highest risk of corrosion. The pre-energisation DCVG survey will need to be able to identify all coating defects no matter how small. In addition there may also be a requirement to repair coating defects on the 22” pipeline, since if the pipeline is subjected to stray current interference then coating defects would be locations where metal loss may most likely occur. In the absence of stray current interference the small coating defects would normally be protected by the pipeline CP system and would not need to be repaired. However, if the line is subjected to DC interference it may even be necessary to excavate and repair any defects to reduce the risk of corrosion and a provisional cost should be allowed for this activity. The presence of stray DC current would make a DCVG survey difficult as there may be DC current flowing on or off the pipeline, which would make data interpretation difficult. It is difficult to separate the DC current applied for the DCVG survey from the stray current from say the HVDC transmission system. CIP surveys will also be problematical in future with a potential controlled TR installed, which will be required to mitigate the interference. It is generally not possible to switch these units in a suitable manner to carry out CIP surveys. It is recommend that CIP and DCVG surveys are conducted on the pipeline prior to energisation of any HVDC transmission system as there may be a strong possibility that such surveys may not be able to be conducted safely and effectively in the future.

6.3 Pipeline Location and Depth Surveys

The pipeline system is relatively old and as built drawings may need to be updated. It would be prudent to consider a pipeline survey pre-construction of the HVDC system. This will establish the precise location of the pipeline and its depth. It would also be of assistance to SMart Wind as they would have an accurate record of the pipeline route to assist in their design and any crossing proposals. If such a survey is planned it would need to be undertaken prior to energisation of the HVDC system so that the risks to operatives in terms of touch or step potential are reduced. Indeed, if there is electrical interference on the pipeline from the HVDC system, which could interfere with the data collection this can be avoided if a survey is carried out pre-energisation of the HVDC. Furthermore, as contact with pipeline test posts will be required if this can be made before energisation of the HVDC system this will reduce the touch potential safety risk to the survey crew.

6.4 Pipeline CP System

The pipeline CP system will need to be re-designed, if a HVDC power transmission system is installed. This would mean the installation of potential controlled TR units to replace the existing one, installation of remote monitoring, modifications to CP test posts, installation of ER probes, corrosion coupons, alarms and possibly new CP system groundbeds and TR units.

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The CP system test posts would also need to be replaced with new dead front type CP test posts so that no pipe terminals are exposed. If a member of the public was to touch a test post stud at the same time as a high voltage on the pipeline from a transmission system fault they could be exposed to a potentially hazardous touch potential. Philips 66 Ltd may need to consider replacing all CP test facilities so that only Phillips 66 Ltd personnel can gain access to the pipe connection. The design work should commence before energisation of the HVDC power system to reduce the increased risk to personnel working on the pipeline post HVDC system energisation. The dead front CP test posts would help ensure the public safety in the event of electrical shock risks. There may be modifications to the CP system required once the HVDC system is energised. Installation of new CP groundbeds may be required particularly near the refinery. This would involve land acquisition and provision of an AC supply and could be expensive. Indeed, it is highly likely that at least 1 new CP station would be required closer to the refinery using a potential controlled TR unit. A new transformer rectifier will also need to be installed within the Tetney Terminal to replace the existing one. Data logging would also need to be conducted to determine the status of the pipeline to soil potential before energisation of the HVDC cable to provide baseline information on the level of DC inference pre-energisation of the HVDC system. This work could be extensive, would be time consuming and hence costly. The CP test facilities would need to be modified to include buried reference electrodes and corrosion monitoring devices that are not already installed.

6.5 Intelligent PIG Survey

The pipeline system is subject to intelligent pigging at defined intervals. This is the main method of confirming the pipeline integrity. It would be prudent for Phillips 66 Ltd to conduct an intelligent pig run on the 22” pipeline immediately prior to the energisation of the HVDC system. Thereafter the intelligent pig frequency may need to be increased above that presently utilised, as this would be the main method of confirming pipeline integrity but also determining if the HVDC system has caused any problems or corrosion on the pipeline system. The sensitivity level for the PIG survey would need to be maximised so that all defects can be identified even ones less than 10% of wall thickness. The increased pigging frequency would need to be considered in the ongoing operational costs. A baseline pig run prior to the energisation of the HVDC system would only be required if SMart Wind would not accept the latest pig run data that Phillips 66 Ltd has as the baseline condition. Intelligent pig runs are expensive due to the nature of the products being transported. However, it is highly likely that Phillips 66 Ltd will incur additional costs due to the likely increased frequency of pigging that would be required once the HVDC transmission system is operational. The precise value of these costs is difficult to predict at this stage and would be dependent upon the extent of interference that is experienced, the number of cable faults that occur and period of time that any imbalance in the HVDC system has occurred for. This will have an impact on the pigging frequency and costs that Phillips 66 Ltd would incur.

6.6 Mathematical Modelling

Mathematical modelling would be required to determine the likely effect of the HVDC system on the step and touch potential risk to the pipeline system.

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The risks to the general public and Phillips 66 Ltd personnel would need to be established by mathematical modelling. The modelling should provide information on the likely potential rise on the pipeline system and whether additional earthing will be required at the HVDC cable to pipeline close proximity locations. Mathematical modelling would be relatively expensive and the costs given in Appendix A are provisional ball park costs. It should be noted that SMart Wind has stated they will carry out GPR modelling and earthing studies for the cable transmission system. If this is the case then the provisional costs for this activity included in the budget cost estimate as a Philips 66 Ltd cost can be removed. Mathematical modelling of the level of induced voltage created on the pipeline due to the increased AC power loading on any overhead power lines as a result of the HVDC transmission system would need to be undertaken as well.

6.7 6” Condensate Pipeline

The 6” condensate pipeline parallels the 22” pipeline for most of the 22” pipeline route. It would make sense for Phillips 66 Ltd and ConocoPhillips (UK) Ltd to combine resources especially on the design of any modifications to the pipeline systems as interference on one pipeline would be transferred to the other and vice versa. The CP monitoring system for both pipelines may need to be re-designed. The CP system for both pipelines is a joint CP system at present. There is a particular concern in relation to the 6” condensate pipeline since this pipeline has a low wall thickness of only 4.5mm and if subjected to stray current interference could suffer failure i.e. through wall perforation before the 22” pipeline.

6.8 HVDC Substations

The location of one of the HVDC substations and DC/AC converter stations is close to the E ON Killingholme Power Station. The location of the HVDC substation offshore has not been shown on drawings or identified. Phillips 66 Ltd would need to establish that the offshore substation/AC/DC converter is not close to any Phillips 66 Ltd asset. If it is then the DC stray current risk on that asset would need to be assessed. SMart Wind would also be advised to address the DC interference risk on any offshore HVDC AC/DC converters as they could find numerous issues in the longer term, since any DC leakage current could significantly affect the integrity of their offshore assets.

6.9 DC Interaction SMart Wind Cables

There may be a need for SMart Wind to carry out interaction testing on their cable system from the Phillips 66 Ltd CP system. This will need to be considered as part of their design documentation. This applies whether an AC or DC transmission system is used.

7. Pre Construction Activities and Costs HVAC Transmission

7.1 General

The following sections describe some of the issues and activities that will need to be considered by Phillips 66 Ltd and SMart Wind as a result of the proposed project, if a HVAC transmission system is to be installed. Some of the costs that Phillips 66 Ltd may incur as a result of the HVAC system are identified in Appendix A.

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It is to be stressed that some of the activities described may not be required and that the costs provided in Appendix A are indicative values only at this stage. The costs do not include any costs that Phillips 66 Ltd may incur for additional management time for the interference issues on the 22” pipeline system, during construction or extra operating and inspection costs associated with the HVAC transmission system in the future, whilst legal fees would also need to be added to this cost estimate. SMart Wind has provided indicative technical information at this stage and this report may need to be amended when additional information is provided.

7.2 CIP and DCVG Surveys

The existing 22” and 6” pipelines are not subject to significant levels of AC interference at present. However, there is AC interference on the 22” pipeline close to Healing that is close to the minimum AC discharge current density value give in BS EN 15280 and if the SMart Wind project does proceed there is a possibility that the pipelines could be subjected to AC interference in the future and at some locations the interference could exceed the values given in BS EN 15280 unless remedial measures are taken.. CIP and DCVG surveys are generally conducted at the frequencies required by Phillips 66 Ltd based upon RBI without any difficulties. However, If a pipeline is subject to AC stray current interference then conventional over the line pipeline surveys such as CIP and DCVG may not be able to be conducted as easily in future as they would in the absence of AC interference. Indeed, data interpretation from CIP and DCVG surveys on pipelines that are susceptible to AC interference may problematical. It should however be noted that whilst it can be problematical to conduct CIP surveys on pipelines with AC interference, it is not as problematical as trying to conduct a CIP survey on pipelines with significant levels of DC interference. To conduct a CIP survey on a pipeline with AC interference would require CIP survey equipment with a sufficiently high AC rejection capability but if earthing is installed on the 22” pipeline to combat the induced AC then that will make ON/OFF CIP surveys difficult, as the nature of the earthing construction means that it can provide DC current to the pipeline by rectifying induced AC and OFF potential surveys cannot be easily conducted. A DCVG survey will also be able to identify coating defects on the pipeline systems. These will be locations where there is the highest risk of AC corrosion especially at the pipeline to HVAC transmission line parallelisms, where either the cable route or pipeline route deviate from each other. If zinc earthing is installed the DC decouplers provided limit the ability to carry out DCVG surveys. It is recommend that CIP and DCVG surveys are conducted on the pipeline prior to energisation of any HVAC transmission system as there may be a strong possibility that such surveys may not be able to be completed in the future. The DCVG surveys that are conducted at present do not report all coating defects as the pipeline CP system protects these. However, if the HVAC system is installed then all DCVG defects no matter how small may need to be located and possibly repaired. This is because there may be exposed steel at these defects, which could if subject to AC interference be locations where AC corrosion on the pipeline could occur, if AC discharge current densities exceeded the maximum AC discharge current density criterion.

RPT-11-577-02 REV 5 Page 23 of 28

7.3 Pipeline Location and Depth Surveys

The pipeline system is relatively old and as built drawings may need to be updated. It would be prudent to consider a pipeline route and depth survey pre-construction of the HVAC system. This will establish the precise location of the pipeline and its depth. If such a survey is planned it would be best to undertake it prior to energisation of the HVAC system so that the risks to operatives in terms of touch or step potential are reduced and if there is electrical interference on the pipeline from the HVAC system, which interferes with the data collection this can be avoided, if a survey is carried out pre-energisation of the HVAC system.

7.4 Pipeline CP System

The pipeline CP system would need to be re-designed, if a HVAC transmission system was installed. This would mean the installation of a new potential controlled TR unit, TR units with enhanced AC rejection, remote monitoring, and modifications to CP test posts, installation of ER probes, AC corrosion coupons and alarms. The design work and installation work associated with the CP system modifications should commence before energisation of the HVAC power to reduce the risk to personnel working on the pipeline post HVDC system energisation. It is highly likely that all existing CP test facilities will need to be replaced with dead front ones to ensure the public safety in the event of electrical shock risks. There would need to be AC coupons installed to monitor the AC corrosion risk on the pipeline. There may be modifications to the CP system required once the HVAC system is energised. Installation of new CP groundbeds may not be required if a HVAC power transmission system is used. However, new land acquisition may be required if additional earthing is installed on the pipeline and this could be expensive. Data logging would also need to be conducted to determine the status of the pipelines before energisation of the HVAC cable to provide baseline information on the level of AC interference. This work could be extensive, would be time consuming and hence costly. The CP test facilities would include buried reference electrodes and corrosion monitoring devices that are not already installed.

7.5 Intelligent PIG Survey

The 22” pipeline is subject to intelligent pigging at defined intervals. This is the main method of confirming pipeline integrity.

It would be prudent for Phillips 66 Ltd to conduct an intelligent pig run on the 22” pipeline immediately prior to the energisation of the HVAC system. Thereafter the intelligent pig frequency may need to be increased as this would be the main method of confirming pipeline integrity but also determining if the HVAC system has caused any problems or corrosion to the pipeline system

The increased pigging frequency would need to be considered in the ongoing operational costs. A baseline pig run prior to the energisation of the HVAC system would only be required if SMart Wind would not accept the latest pig run data that Phillips 66 Ltd has as the baseline condition.

RPT-11-577-02 REV 5 Page 24 of 28

Intelligent pig runs are expensive due to the nature of the products being transported. However, it is highly likely that Phillips 66 Ltd will incur additional costs due to the likely increased frequency of pigging that would be required. The precise value of these costs is difficult to predict at this stage and would be dependent upon the extent of interference that is experienced. This will have an impact on the pigging frequency and costs that Phillips 66 Ltd would incur.

7.6 Mathematical Modelling

Mathematical modelling would be required to determine the likely effect of the HVAC system on the step and touch potential risk to the pipeline system. The risks to the general public and Phillips 66 Ltd personnel would need to be established by mathematical modelling. The modelling should provide information on the likely potential rise on the pipeline system and whether additional earthing will be required on the pipeline during short term or longer term interference situations. The close proximity of the cross bonded earthing connection arrangements would be locations where additional earthing may be required on the 22” pipeline. Mathematical modelling would be relatively expensive and the costs given are provisional ball park costs. Mathematical modelling of the level of induced voltage created on the pipeline due to the increased AC power loading on any overhead power lines as a result of the HVAC transmission system would also need to be undertaken.

8. Discussions

8.1 Third Party Pipelines

There are a number of third party pipelines in the area and they may also suffer stray current interference from the HVDC/HVAC system. Anglian Water Authority has a pipeline system that is bonded to the Phillips 66 Ltd pipeline and if there is current pick up on the Phillips 66 Ltd pipeline this could flow to the AWA lines and vice versa.

SMart Wind would be required to indemnify AWA for any interference induced on their pipeline system by connection to the Phillips 66 Ltd pipelines and vice versa.

All third party pipeline operators in the area would need to be consulted as any decision by Phillips 66 Ltd could affect their pipeline system. There should ideally be a forum formed by all pipeline operators in the area to discuss issues associated with interference from the SMart Wind system on pipeline management and this would incur costs to Phillips 66 Ltd. There may also be discussions with the HSE on the possible risks associated with this project.

8.2 Construction Methods

Details of the proposed construction methods would need to be agreed with SMart Wind. This would relate to construction activities within the Phillips 66 Ltd wayleave or if pile driving and explosive detonation takes place at agreed distances from the pipeline. In the case of pile driving operations or other operations that could create a fatigue loading these would generally be restricted to no closer than 15m from the third party pipeline and for explosive detonation no closer than 400m. However, as there are no proposed crossings of the 22” pipeline there would not need to be any crossing agreements in place. Nevertheless, details of the installation techniques that will be employed for the length of parallelism of the 22” pipeline should be provided for reference. It would be recommended that Phillips 66 Ltd Safe Working Procedures for Work within the Vicinity of Phillips 66 Ltd pipelines be up dated.

RPT-11-577-02 REV 5 Page 25 of 28

IGE/SR/28 should be utilised as the guidance document for trenchless crossing techniques, if the route details are amended to include a crossing of the 22” pipeline.

Phillips 66 Ltd may be involved in costs for the provision of inspection personnel to identify pipeline locations, supervise construction within the SMart Wind working width, if required. This would be a cost that Phillips 66 Ltd would need to pass on to SMart Wind. There will be labour costs associated with management of the temporary protection of the Phillips 66 Ltd pipeline during the works e.g. pre construction surveys, detailed design of temporary protection to the Phillips 66 Ltd pipeline at temporary plant crossing points, if required. If the power transmission line installation is carried out in the same manner as that on a pipeline spread there should not be a requirement to cross the 22” pipeline. However, if any crossings of the 22” pipeline are required to carry out surveys, erect working width fences or for construction then suitable pre-cautions would need to implemented to ensure the 22” pipeline is protected from mechanical plant and the likely loads that would be experienced.

8.3 Notification of Fault

If a HVDC system was to be provided SMart Wind would need to confirm and have an agreement in place to notify Phillips 66 Ltd of any fault on the HVDC system and the nature of the fault. There may need to be a remote monitoring system installed that would trigger an alarm if the pipeline was subjected to high voltage transients. In addition if the cable system was to operate in a monopolar configuration for any period of time then Phillips 66 Ltd would need to be notified. Suitable arrangements would need to be in place to identify any times and the duration of time that incorrect operation of the HVDC system occurred for.

8.4 Philips 66 Ltd Management

Phillips 66 Ltd will be involved in additional costs associated with management of the pipeline system going forward. This could involve costs associated with specialist support services, attendance at meetings with other pipeline operators and legal counsel.

8.5 Wayleave Agreements

The wayleave agreements for the 22” pipeline would need to be reviewed and some possibly amended in discussion with the land owners and other pipeline operators. The construction of the power transmission system may affect existing access wayleaves and could limit access to the 22” pipeline in the event of an emergency or repair situation. It may be the case that ConocoPhillips (UK) Ltd would only be able to gain access to the 6” pipeline by crossing the 22” pipeline. Working in proximity agreements would need to be in place and if SMart Wind or the independent operators wished to gain access to their transmission system they may need to do so by crossing the 22” pipeline. In view of the close proximity of the 22” to the proposed power transmission system there may be requirement for personnel safety to isolate the power system in the future for a short period of time if any work is required on the 22” pipeline. Any such requirement would only be able to be determined once all the earthing and ground potential rise studies have been completed.

RPT-11-577-02 REV 5 Page 26 of 28

9. Conclusions

9.1 Summary of Technical Issues

Phillips 66 Ltd personnel and the general public could be exposed to an increased safety risk because of the construction and operation of both the HVDC and HVAC power transmission systems and these risks would need to be mitigated during the design stage. The HVDC system it is considered would pose the highest risk in terms of corrosion and pipeline integrity of the two proposed systems. However, the precise risk cannot be accurately quantified at this stage until the details of the electrical system are reviewed and discussed with SMart Wind. Indeed, if the level of DC leakage current is too high this could preclude the use of a HVDC system altogether because of the enhanced stray current corrosion risk, which may not be able to be mitigated by pipeline operators undertaking design modifications to pipeline CP systems. SMart Wind would be recommended to fully evaluate the performance of any system they propose to ensure it will not cause significant levels of damage to other pipelines. There is also a risk of AC corrosion from the HVAC transmission system. Here again the risk cannot be quantified at this stage but risk mitigation measures can be implemented during the design phase to reduce the level of risk. In the case of a buried HVAC system as opposed to an overhead power line the likely levels of induced AC are generally lower. However, until further detailed investigation is undertaken the level of risk cannot be fully ascertained.

9.2 Summary of Costs

The total costs that Phillips 66 Ltd could incur from the construction of the SMart Wind HVDC cable system could be significant and they are summarised in Table 1 below.

A detailed breakdown of costs is given in the Tables in Appendix A of this document

RPT-11-577-02 REV 5 Page 27 of 28

Table 1 Budget Cost to Phillips 66 Ltd Associated with the Cost of the HVDC Cables

Item Cost Area Cost

1.0 Pre Construction Costs £ 571,000

2.0 Pipeline CP System Design and Modification Costs

£ 635,000

3.0 HVDC Cable Construction Cost £ 150,000

4.0 HVDC Commissioning Costs £ 269,000

5.0 Ongoing Operation and Monitoring Costs annual fee

£ 233,000

6.0 Total Budget Cost to Phillips 66 Ltd for HVDC cable system up to 1

st Year of Operation

£1,857,000

The costs stated in Appendix A are purely provisional, and are strictly approximations. Indeed, some costs could be higher than quoted and some costs could be lower, whilst some activities might not be required. The ongoing annual costs could be quite significant due to the possible increased pigging frequency. However, here again these costs could vary. The costs quoted are based upon estimated costs in 2013. The costs are for the 22” pipeline system only and it should be noted that item 5.0 is an annual fee. There will be ongoing costs to Phillips 66 Ltd and again these costs are strictly provisional and are provided for indicative purposes only at this stage. A figure of £150,000 has been included to cover Phillips 66 Ltd inspection costs, whilst the cable transmission system is being constructed. It may be necessary for Phillips 66 Ltd to employ inspectors to oversee the construction work e.g. crossing of the 22” pipeline by construction plant. However, if SMart Wind have sufficient mitigation measures in place enhanced surveillance by Phillips 66 Ltd may not be required. This figure has been added to both the HVDC and HVAC power transmission system costs. The cost summary has been provided to give an indication of possible costs but would need to be adjusted based upon information provided by SMart Wind, which at this stage has been limited. These costs it should be stressed are strictly budget and provisional costs and exclude legal fees and Phillips 66 Ltd management costs. They are a ball park indication of costs which is the best that can be achieved based upon the information available at this stage of the project by SMart Wind The costs for the pipeline monitoring and operation for the HVAC option are summarised on Table 2

Table 2 Budget Cost to Phillips 66 Ltd Associated with the Cost of the HVAC Cables

Item Cost Area Cost

1.0 Pre Construction Costs £ 571,000

2.0 Pipeline CP System Design and Modification Costs

£ 725,000

3.0 HVAC Cable Construction Costs £ 150,000

4.0 Commissioning Costs £ 269,000

5.0 Ongoing Operation and Monitoring Costs annual fee

£ 233,000

6.0 Total Budget Cost to Phillips 66 Ltd for HVDC cable system up to 1

st Year of Operation

£1,948,000

RPT-11-577-02 REV 5 Page 28 of 28

10. Recommendations 10.1, Based upon the information provided to date the Phillips 66 Ltd 22” crude oil pipeline would

appear to be at risk of stray current interference from the HVDC power system and AC corrosion from the HVAC system.

10.2 A fully detailed assessment of the risk of AC and DC interference on the Phillips 66 Ltd

pipeline system should be conducted once precise details of the power system are confirmed by SMart Wind.

10.3. In the event the project does proceed a joint consultative forum with other pipeline operators

should be established. 10.4 SMart Wind would need to indemnify Phillips 66 Ltd against any costs it may incur if the

project was to progress. It should be noted that these costs could be considerable and may exceed those identified in this report.

10.5 SMart Wind should carry out their own technical assessment of the proposed HVDC and

HVAC systems to ensure that they feel confident that the systems that have proposed do not result in significant levels of interference on third party assets.

10.6 The design responsibility for the power transmission system should rest with SMart Wind.

Phillips 66 Ltd should not accept design responsibility. 10.7 If either a HVDC or HVAC system is proposed then mathematical modelling should be

conducted to determine what effect the extra load on the existing overhead NG power lines will have on the levels of interference on the Phillips 66 Ltd’s assets.

10.8 A failure mode and effect analysis would need to be conducted to ascertain the possible

pipeline failure and risk mitigation methods to be implemented to combat the interference risks.

10.9 If the power transmission system installation does proceed then a detailed operating and

maintenance document and CP system design document would need to be prepared. To identify the over the line survey techniques that would be used, additional corrosion monitoring required and information that SMart Wind would need to provide on the performance of their power transmission system

RPT-11-577-02 APPENDIX A REV 1 Page 1 of 5

Appendix A: Budget Cost Summary

NB Costs in this section are indicative costs only at this stage

RPT-11-577-02 APPENDIX A REV 5 Page 1 of 5

Table 1

Pre Construction Costs 22” Crude Oil Pipeline HVDC/HVAC System 2013

Item Activity Reason Cost 1.0 Pipeline Location and

Depth Survey To confirm location of pipeline and depth of pipeline along route prior to energisation of HVDC in case interference affects location

£ 12,000

2.0 DCVG Survey Conduct DCVG survey along entire pipeline route to locate coating defects. If there is DC interference This survey may not be possible in the future. If there is AC interference defect locations could be those were AC corrosion could occur

£17,000

3.0 CIP Survey Conduct CIP survey along entire pipeline route to locate coating defects. If there is DC Interference This survey may not be possible in the future

£12,000

4.0 Expose and Repair DCVG defects

If any DCVG defects are exposed at the cable crossing locations or at other points along the line they may need to be exposed A provisional sum should be included for this activity

£60,000

5.0 Conduct Base Line Data Logging

Install data Logger to confirm variation in AC and DC Potential at CP test facilities along pipeline route prior to energisation of the power systems

£ 50,000

6.0 Meetings to Discuss Action Plan

Meetings will be Required to Discuss Action for Future Surveys

£10,000

7.0 Production of Pre Construction CP report

Pre construction CP status report. Conduct detailed survey of pipeline CP system

£15,000

8.0 Establish Pipeline Operators Forum

Joint Group will be required as all operator will need to be involved

£5,000

9.0 Determine Short Term and Long Term Interference

Mathematical modelling will be required to determine risks to Phillips 66 Ltd personnel from fault situations

£75,000

10.0 Pre energisation intelligent pig survey 22 inch

Intelligent pig survey to confirm actual integrity levels on pipeline prior to works commencing

£300,000

12.0 Consultation with HSE and Safety Review SMart wind

Provision of external specialist technical support

£15,000

Total Budget Costs:

£571,000.00

RPT-11-577-02 APPENDIX A REV 5 Page 2 of 5

Table 2 Pipeline CP System Modification Costs 22” Pipeline HVDC System

Item Activity Reason Cost 1.0 Corrosion Monitoring

Design and CP System Design of Corrosion Monitoring system to monitor effect of DC Interference

£60,000

2.0 Install potential controlled CP system for Pipeline at existing TR Locations

DC interference may cause variations in pipe to soil potential and a potential controlled CP system will be required

£80,000

3.0 Install additional groundbeds and potential controlled TR units

The highest level of interference would be expected to be near Immingham and new TR units may be required here need AC, new land etc

£100,000

4.0 Dead Front CP Posts Required to ensure No Contact for General Public

Post Required to ensure public could not contact pipeline in event of fault situation need to replace all CP Posts

£100,000

5.0 Install Remote Monitoring

Install remote monitoring at selected test facilities to confirm if alarm exists

£100,000

6.0 Meetings to Discuss Works

Meetings will be Required to Discuss Action for Future Surveys

£20,000

7.0 Installation of Corrosion Monitoring coupons, ER probes etc

Corrosion monitoring System will be Required

£80,000

8.0 Establish Arrangement for Phillips 66 Ltd to be Informed of Faults on HVDC System

Phillips 66 Ltd will need to have a system in place to Monitor when faults exists on the HVDC system

£10,000

9.0 Training of Phillips 66 Ltd personnel

Phillips 66 Ltd will incur costs for training of their personnel in risks

£15,000.

10,0 Installation of earthing Additional Earthing at points where powerline deviates may be required to mitigate risk

£50,000

11.0 Discussions with other pipeline operators

All pipe line Operators will need to be consulted

£20,000

Total Budget Costs:

£635.000

RPT-11-577-02 APPENDIX A REV 5 Page 3 of 5

Table 3

Pipeline CP System Modification Costs 22” Pipeline HVAC System Item Activity Reason Cost 1.0 Corrosion Monitoring

Design and CP System Design of Corrosion Monitoring system to monitor effect of DC Interference

£60,000

2.0 Install potential controlled CP system for Pipeline at existing TR Locations

DC interference may cause variations in pipe to soil potential and a potential controlled CP system will be required

£80,000

3.0 Install additional Zinc earthing at locations identified following modelling

The highest level of interference would be expected to be near Immingham and additional land may be required for zinc earthing

£200,000

4.0 Dead Front CP Posts Required to ensure No Contact for General Public

Post Required to ensure public could not contact pipeline in event of fault situation need to replace all CP Posts

£100,000

5.0 Install Remote Monitoring

Install remote monitoring at selected test facilities to confirm if alarm exists

£100,000

6.0 Meetings to Discuss Works

Meetings will be Required to Discuss Action for Future Surveys

£20,000

7.0 Installation of Corrosion Monitoring coupons, ER probes etc

Corrosion monitoring System will be Required

£80,000

8.0 Establish Arrangement for Phillips 66 Ltd to be Informed of Faults on HVAC System

Phillips 66 Ltd will need to have a system in place to monitor when faults exists on the HVAC system

£10,000

9.0 Training of Phillips 66 Ltd personnel

Phillips 66 Ltd will incur costs for training of their personnel in risks

£15,000.

10,0 Installation of earthing Additional Earthing at points where powerline deviates may be required to mitigate risk

£50,000

11.0 Discussions with other pipeline operators

All pipe line Operators will need to be consulted

£20,000

Total Budget Costs:

£725,000

Table 4

Cost Excluded in Cost Summaries

Item Activity

1.0 Any additional Land Purchase Costs

2.0 Phillips 66 Ltd management time attending meetings, time leasing with cable operator, management time correspondence, increased inspection and monitoring costs

3.0 Legal Fees

4.0 Land Agent Fees

5.0 Purchase of additional land

6.0 Consequential Costs

7.0 Insurances

8.0 Future possible repair costs

RPT-11-577-02 APPENDIX A REV 5 Page 4 of 5

Table 5

HVDC System Commissioning Costs Item Activity Reason Cost 1.0 Commissioning of

Remote Monitoring Phillips 66 Ltd will need to ensure remote monitoring is commissioned

£60,000

2.0 CP system commissioning

Phillips 66 Ltd will need to commission CP system for pipeline system

£60,000

3.0 Data Logging 7 day data logging at all CP posts will be required

£100,000

4.0 CIP Survey completed A CIP survey will be required along the whole length of the pipeline after energisation

£15,000

5.0 CP report Completed Fully detailed Report completed on CP system

£12.000

6.0 Pipeline Group Meetings

Meetings with all concerned parties to discus findings

£15.000

7.0 Up Date of Documents Safety Files and construction drawings and specifications will need to be updated

£12,000

8.0 Phillips 66 Ltd and pipeline operator meetings

Would need to review internally implications of results and also possibly discuss these with other operators

£10,000

Total Budget Costs:

£269,000

Table 6

HVAC System Commissioning Costs Item Activity Reason Cost 1.0 Commissioning of

Remote Monitoring Phillips 66 Ltd will need to ensure remote monitoring is commissioned

£60,000

2.0 CP system commissioning

Phillips 66 Ltd will need to commission CP system for pipeline system

£60,000

3.0 Data Logging 7 day data logging at all CP posts will be required

£100,000

4.0 CIP Survey completed A CIP survey will be required along the whole length of the pipeline after energisation

£15,000

5.0 CP report Completed Fully detailed Report completed on CP system

£12.000

6.0 Pipeline Group Meetings

Meetings with all concerned parties to discus findings

£15.000

7.0 Up Date of Documents Safety Files and construction drawings and specifications will need to be updated

£12,000

8.0 Phillips 66 Ltd and pipeline operator meetings

Would need to review internally implications of results and also possibly discuss these with other operators

£10,000

Total Budget Costs:

£269,000

RPT-11-577-02 APPENDIX A REV 5 Page 5 of 5

Table 7

Ongoing Pipeline Monitoring Costs Yearly Figures HVDC and HVAC Item Activity Reason Cost

1.0 Additional CP System Monitoring

Phillips 66 Ltd will need to modify monitoring regime to increase frequency due to increased risk

£12,000

2.0 6 monthly group meetings and internal meetings

Phillips 66 Ltd will need to meet with other pipeline operators on a more frequent basis

£3,000

3.0 Data Logging 7 day data logging at all CP posts will be required going forward to see if there any problems

£18,000

4.0 Excavation to coupons at regular intervals

CP monitoring system commissioned

£20,000

5.0 Phillips 66 Ltd inspection costs

Additional Surveillance would be required along pipeline routes

£15,000

7.0 Monitoring and operation of remote monitoring system

There will be additional resources and operation costs for the handling and control of the remote monitoring system

£15,000

8.0 Increased pigging frequency costs 22” line

Because of the risk to the pipeline system and based upon the CP monitoring data and number of faults increased pigging costs may be required provisional sum based on 3 yearly interval

£100,000

9.0

May need to expose pipeline to investigate issues

If pig run finds defects these may need to be inspected pending a decision to further action

£50,000

Total Budget Costs:

£233,000

RPT-11-577-02 APPENDIX B REV 5 Page 1 of 5

Appendix B: Risk Summary Table

RPT-11-577-02 APPENDIX B REV 5 Page 2 of 5

Table 1

Summary of Risks to 22” Pipeline from DC/AC Power Transmission System Item Risk Mitigation Method

1.0 Damage to pipeline by load imposed by construction plant crossing operational pipeline

Phillips 66 Ltd need to approve temporary crossing designs and ensure works carried out in accordance with Phillips 66 Safe Working procedures. Phillips 66 Ltd may require inspection personnel on site

2.0 Construction activities within pipeline wayleave

Work within 22” wayleave to be controlled and had excavation required. Safe working procedures to be agreed

3.0 Piling driving or similar operations close to pipeline

Blasting and piling operations within pipe to be controlled to within defined limits

4.0 Trenchless crossing of 22” pipeline

Trenchless crossing technique and method to be approved requirements of IGE/SR/28 to be followed

5.0 DC stray current interference risk SMart Wind to limit DC leakage current, dc stray current interference monitoring required

7.0 Over the Line surveys on pipelines with AC/DC interference risk

It may not be possible to conduct over the line surveys CIPS/DCVG when pipelines are subject to interference baseline surveys before energisation of power system to be conducted

8.0

Faults on AC/DC power transmission systems

Touch and step potentials risk need to be modelled and suitable risk mitigation methods put in place

9.0

High rates of corrosion during fault conditions on DC system

Notification of faults required to pipeline operator, automatic potential controlled CP system and additional corrosion monitoring systems

10.0 AC corrosion Modelling of AC corrosion risk to pipeline additional monitoring required and AC corrosion risk reassessed

11.0 In Line inspection Pigging frequency may need to be increased to provide baseline data if there are any serious problems identified

12.0 Operation and maintenance More frequent operation and maintenance checks to be performed if interference is detected

13.0 Inference transferred to our pipeline systems

Stray current interference may be transmitted to other pipelines. Joint pipeline operator forum to be established to share data

Copyright:© 2013 Esri, DeLorme, NAVTEQ, TomTom

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LegendSMartWind cable route

SmartWind corridor

Smartwind cable 500m corridor

Route 1) GH Parker

Route 1) GH Parker (stoned)

DD Route 1) GH Parker (existing stoned track)

Option 1a) If Option 1 unavailable

Option 1a) (stoned) If Option 1 is unavailable

Route 2) Stonebridge Farm Route

Route 2) Stonebridge Farm Route (stoned)

Route 2a) Stonebridge Farm Route

Route 2a) Stonebridge Fram Route (stoned)

Route 3) GH Parker. Access to foreshore (possibly not stoned)

Route 3) GH Parker. Access to foreshore (stoned)

Seawall, Saltmarsh and Sand Dunes Crossing

Existing Pipeline Route

Design Route

Marsh Area

±

0 0.5 1 1.5 20.25Kilometres

PIPE STRINGS

ACCESS ROADCAR PARK

OFFICES

GRADED GROUND TO SUIT PIPELINEPROFILE

COFFERDAM

TUNNEL ENTRY

PIPELINE DRILL RIGSITE AREA

SEAWALL

Coordinate System: British National GridProjection: Transverse MercatorDatum: OSGB36False Easting: 400,000False Northing: -100,000Central Meridian: -2.00Scale Factor: 0.9996Latitude of Origin: 49.00Units: Metre

Access to Site and Beach

Horseshoe Point