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CONTENTS
Page No
CONTENTS 1
1. INTRODUCTION 1.1
2. EXECUTIVE SUMMARY 2.1
3. BACKGROUND INFORMATION 3.1
3.1 THANET OFFSHORE WIND LIMITED 3.1
3.2 THANET OFFSHORE WIND FARM - PROJECT DETAILS 3.1
3.3 AS-BUILT INFORMATION 3.2
3.4 ADDITIONAL INFORMATION 3.2
4. DESCRIPTION OF ITEMS TO BE DECOMMISSIONED 4.1
4.1 OFFSHORE SUBSTATION 4.1
4.2 OFFSHORE WTG STRUCTURES 4.2
4.3 SUBSEA CABLES 4.4
4.3.1 Export Cables 4.4
4.3.2 Interarray Cables 4.4
4.3.3 External Cable Protection .4.4
5. DESCRIPTION OF PROPOSED DECOMMISSIONING MEASURES..
5.1 PLAN OF WORKS AND INTEGRATION
5.2 PROPOSED METHOD OF REMOVAL
5.2.1 Offshore Substation
5.2.2 Offshore WTG Structures
5.2.3 Offshore Cables
5.3 PROPOSED WASTE MANAGEMENT SOLUTIONS
5.4 DETAILS OF ANY ITEMS WHICH MAY BE LEFT IN SITU
OFFSHORE FOLLOWING DECOMMISSIONING
...... 5.1
5.1
5.1
5.2
5.2
5.3 5.3
5.3
6. ENVIRONMENTAL IMPACT ASSESSMENT. 6.1
7. CONSULTANTS WITH INTERESTED PARTIES 7.1
8. COSTS 8.1
9. FINANCIAL SECURITY 9.1
10. SCHEDULE 10.1
11. PROJECT MANAGEMENT AND VERIFICATION 11.1
MAY 2008 Page 0.1 of 0.2
12. SEABED CLEARANCE 12.1
13. RESTORATION OF THE SITE 13.1
14. POST DECOMMISSIONING MONITORING, MAINTENANCE AND
MANAGEMENT OF THE SITE 14.1
15. SUPPORTING STUDIES 15.1
16. APPENDIX 1 - ENVIRONMENTAL STATEMENT SUMMARY 16.1
17. APPENDIX 2 -- CASHFLOW SUMMARY 17.1
MAY 2008 Page 0.1 of 0.2
1. INTRODUCTION
Thanet Offshore Wind Limited (TOW), as the owner of the Thanet Offshore Wind Farm (Thanet)
project, has prepared this Decommissioning Plan in accordance with the requirements of the
Energy Act 2004. Construction of the project is currently planned to commence shortly and be
completed during 2009. This Decommissioning Plan covers the elements of the project that are
planned to be built offshore and is based on the known parameters at the Thanet site and on
information received from the main contractors who have been appointed as Preferred
Contractors to the project. The Decommissioning Plan will be reviewed as the project progresses
and detailed design, construction and installation works are undertaken and completed. It will
then be reviewed at least every five years to ensure that it is compliant with the legislation in
place at that time.
There will be a requirement to decommission at the end of the operational life of the Thanet
project. The scope of the decommissioning works described here is determined by the legislation
and guidance in place at this point in time and involves those accessible installed components of
the wind farm. This includes the Offshore Substation (Topsides and Jacket Structure); all of the
Wind Turbine Generator (WTG) components; part of the WTG Foundations and approximately
10m sections of the Export Cables and Interarray Cables close to the offshore structures. The
cable sections to be removed will be the sections of cable exiting from the J/1-tubes on the
structures to the grade-in point of cable burial protection for the subsea cables.
This Decommissioning Plan only covers the offshore elements of the Thanet project. The
decommissioning of the onshore elements will be covered under general planning regulation.
Following an Environmental Impact Assessment (EIA), this decommissioning programme scope
was outlined in the project Environment Statement (ES) dated November 2005, and was widely
consulted on as part of that process. No objections were raised in respect of these
decommissioning proposals or the associated ES.
This programme has been produced in accordance with the Department for Business Enterprise
and Regulatory Reform ("BERR") decommissioning guidance - "Decommissioning of Offshore
Renewable Energy Installations under the Energy Act 2004 Guidance Notes for Industry".
The BERR guidance notes have the following eight programme process stages:
STAGE 1 TOW initiates discussions with BERR and outlines a planned timetable for the
project.
STAGE 2 The Secretary of State issues notice requiring a decommissioning programme
once satisfied with the statutory consents.
MAY 2008 Page 1.1 of 1.2
STAGE 3 Detailed discussions between TOW and BERR, leading to submission of draft
of programme.
STAGE 4 Consultations by TOW. Consideration of the draft programme by Government
Departments and the Crown Estate. BERR prepares decommissioning
Appropriate Assessment (where required under EU Habitats and Birds
Directives).
STAGE 5 Formal submission of programme by TOW.
STAGE 6 Reviews of decommissioning programme.
STAGE 7 Responsible person ensures decommissioning is carried out in accordance
with the programme.
STAGE 8 Responsible person carries out post decommissioning monitoring,
maintenance and management of the site as specified in the programme.
Stage 1 was completed as part of the November 2005 consent applications. Stage 2 has taken
place (the notice from the Secretary of State was received on 19th December 2006) and Stages 3
and 4 have taken place between January 2008 and May 2008. This document represents Stage 5
of the process and is the formal submission of the programme.
It is anticipated that, following signature of contracts, construction of the Thanet project will
commence offshore in 2008 for completion in 2009. Full decommissioning of the project is
therefore not expected before 2049, assuming that replanting of the WTGs takes place, as
expected, after approximately 20 years.
MAY 2008 Page 1.2 of 1.2
2. EXECUTIVE SUMMARY
This Decommissioning Plan describes how the structures comprising the Thanet Offshore Wind
Farm (Thanet) project can be decommissioned in accordance with Annex E of the BERR's
decommissioning guidance (Contents of a Decommissioning Programme). This
Decommissioning Plan has followed the model framework headings below listed in the guidance:
1. Introduction;
2. Executive Summary (this section);
3. Background Information;
4. Description of Items to be Decommissioned;
5. Description of Proposed Decommissioning Measures;
6. Environmental Impact Assessment;
7. Consultations with Interested Parties;
8. Costs;
9. Financial Security;
10. Schedule;
11. Project Management and Verification;
12. Seabed Clearance;
13. Restoration of the Site;
14. Post Decommissioning Monitoring, Maintenance and Site Management; and
15. Supporting Studies.
16. Appendix 1 - Environmental Statement.
17. Appendix 2 - Cash Flow Summary.
Appendix 1 and 2 have been added to assist in explaining relevant aspects of the report and have been referred to in appropriate sections.
This Decommissioning Plan concludes that all the components of the wind farm that the current
legislation requires to be removed could be successfully decommissioned by Jack-up barges and
sent to onshore recycling facilities.
The decommissioning programme scope in this document is consistent with that outlined in the
project Environment Statement (ES) dated November 2005. Appendix 1 summarises the ES
conclusions in respect of the current proposed Decommissioning Plan. These will be reviewed
over time and a full new Environmental Impact Assessment (EIA) will be conducted before
decommissioning actually takes place.
MAY 2008 Page 2.1 of 2.2
The initial draft Decommissioning Plan and associated ES was widely consulted on as part of the
project consenting process, including with all of the bodies mentioned in Annex 2 of the
Decommissioning Notice. The draft plan included all of the material elements of this proposed
plan. No objections were raised in respect of the draft decommissioning proposals or the
associated sections of the ES.
This Decommissioning Plan will be review at least every five years
MAY 2008 Page 2.2 of 2.2
3. BACKGROUND INFORMATION
This section of the Decommissioning Plan contains the background information and details
relating to the Thanet project.
3.1 THANET OFFSHORE WIND LIMITED
Thanet Offshore Wind Limited (TOW) was created to develop opportunities for energy generation
from renewable resources in the Thanet area. TOW was awarded the right to develop an offshore
wind farm in the Thames Estuary Strategic Environmental Assessment (SEA) area by the Crown
Estate under Round 2 of the offshore wind licensing arrangements. All necessary consents for
the construction and operation of the wind farm have been gained following TOW's submission of
the consents application and associated Environmental Statement (ES) for the Thanet project to
the (BERR) in November 2005. The ES contained details of the proposed Decommissioning Plan
and those proposals are consistent with the proposals set out in this document.
3.2 THANET OFFSHORE WIND FARM - PROJECT DETAILS
The Thanet project is located 11.3km offshore from Foreness Point, which is on the eastern most
part of the Kent coastline. The development rights for the Thanet project are based on a 300MW
maximum generation limit. This is sufficient to provide electricity for 240,000 average homes,
which will account for a significant proportion of the energy needs for east Kent.
The maximum height of the Wind Turbine Generators (WTGs) being considered will be 115m
from mean sea level (MSL) to the blade tip in the vertically up position. The minimum clearance
between the blade tip in the vertically down position to mean high water springs (MHWS) level is
22m. The spacing between WTGs will be a minimum of 450m within rows and 675m between
rows.
The WTGs will be interconnected by an offshore 33kV Interarray Cable network and connected to
an Offshore Substation platform where the voltage is stepped up to 132kV. Electricity will be
transferred to shore by two Export Cables, which will be routed to a landfall point in Pegwell Bay.
The subsea cables will be buried to between 1 and 3m (depending on soil type in the area) to
provide adequate protection from all forms of hostile seabed intervention. Grid connection will be
made by cables buried under the A256 Sandwich Road to the existing substation at the disused
Richborough Power Station, from where power will be distributed by the existing local electricity
network.
MAY 2008 Page 3.1 of 3.5
It is likely that changes to the licensing of Offshore Transmission assets (132kV and above) will
come into effect in the next few years and may entail a change in ownership of some of these
assets. TOW will ensure that any and all decommissioning obligations entered into under this
Decommissioning Plan for such assets will be transferred to any new owner, should these
changes come into force, and that this plan is modified to reflect such changes.
The Thanet project will have a design operational life of 40 years (with an expected replanting of
the WTGs after 20 years) after which time it will be decommissioned.
Figure 3.1 shows the location of the Thanet site together with details of the proposed electrical
connection (including the positions of the cable crossing points). Figure 3.2 shows the proposed
cable landfall and onshore cable route to the electrical connection point at Richborough. The
proposed layout of the development, showing the turbine locations and substation location is also
attached to this plan.
3.3 AS-BUILT INFORMATION
The Construction Design and Management (CDM) Regulations require TOW, in its role as Client
for the works, to appoint a CDM Co-ordinator and Principal Contractor for the construction of the
project. All of the contractors and consultants involved with the project will be contracted to supply
comprehensive as-built data for the wind farm, which will be used by the Principal Contractor and
the CDM Co-ordinator to prepare the final Health and Safety file. This will include as a minimum
the following:
• As-built positions for all structures;
• Details of the construction of all structures; and
• Positions, depths of burial and other forms of cable protection for all subsea cables
(both Export Cables and Interarray Cables).
If at any time during the lifetime of the wind farm the as-built details vary, for example, a repair to
a subsea cable, amended details will be prepared for the ongoing live status of as-built data.
3.4 ADDITIONAL INFORMATION
TOW has assimilated considerable data and information in relation to the Thanet site. This has
included the following, which have all previously been provided to the BERR as part of the
consenting process:
• Environmental conditions - wind and wave data, currents, seabed conditions, water
depth etc;
MAY 2008 Page 3.2 of 3.5
• Details of fishing activity and fishing vessels operating in the vicinity of the Thanet site;
• Details of navigational shipping (both types of vessels and routes used); and other
special information on areas of Sabellaria Spinulosa and bird surreys etc.
All of this information will be retained and made available during the decommissioning works.
Where additional information is assimilated during the lifetime of the wind farm, including any
declared Archaeological Exclusion Zones, this will also be made available as required under
TOW's Lease Agreement with the Crown Estate.
MAY 2008 Page 3.3 of 3.5
FIGURE 3.1 LOCATION OF THE THANET OFFSHORE WIND FARM SITE SHOWING DETAILS OF THE PROPOSED ELECTRICAL CONNECTION
MAY 2008 Page 3.4 of 3.5
4. DESCRIPTION OF ITEMS TO BE DECOMMISSIONED
This section of the Decommissioning Plan contains details of all items which TOW believes will
form part of the scope of future offshore decommissioning works. The scope has been broken
down into three separate areas:
1. Offshore Substation;
2. Offshore WTG Structures; and
3. Subsea Cables (Export and Interarray).
These will be predominantly steel or metal items with the exception of the electrical components
on the Offshore Substation and WTG structures, the grouted connections between the piles and
the supporting structures and the WTG blades. The non steel items are chemically inert and will
comprise only a small proportion of the total weight of material to be decommissioned.
4 . 1 O F F S H O R E S U B S T A T I O N
The Offshore Substation for Thanet will consist of a jacket structure, which will be piled to the
seabed and have a welded connection at the top of the piles to the jacket. The Jacket will support
a Topsides structure, which will house the main offshore transformers. The Offshore Substation
will be the 'hub' for the offshore wind farm and provide voltage step up to allow electricity from the
Thanet site to be exported back to shore via two 132kV Export Cables, which will terminate at the
Offshore Substation. There will also be 10 separate arrays of offshore WTGs connected by 33kV
Interarray Cables, which will deliver the generated electricity to the Offshore Substation. Voltage
step up occurs at two transformers on the Offshore Substation prior to the export of the generated
electricity.
The items which will be decommissioned will be as follows:
• All of the Topsides equipment and transformers. As this equipment is likely to have
been installed in modular components, it will be lifted away in a similar fashion;
• The Topsides support structure;
• The Jacket structure, including all of the appurtenances such as J-Tubes and boat
access systems;
• The piles, which will be cut of at 2m below seabed level at the bottom of any scour
hole; and
MAY 2008 Page 4.1 of 4.4
• The sections of cable (both Export and Interarray) which emanate away from the
Offshore Substation from the exit point of the bellmouth on the J-tube to the touchdown
point on the seabed and out further to the transition point where cable burial starts in
the seabed. This will typically be a section of cable 10-25m long. All cables left within
the J-tubes will also be recovered.
It should be noted that any scour holes that have formed at the base of the pile foundations will fill
naturally within a few days after the removal of the pile. The designs for the substation jacket and
topsides are attached.
4.2 OFFSHORE WTG STRUCTURES
The offshore Wind Turbine Generators (WTGs) at Thanet will be installed in the following
sequence. The individual named components are illustrated in Figure 4.1
1. The foundations will consist of a monopile and a transition piece. The monopile
foundation will be driven into the seabed. The Transition Piece will then be installed
over the pile and secured to the monopile with a grouted connection.
2. The Interarray Cables will then laid, buried and pulled onto the foundation platform via
the l-tube.
3. The WTG tower (in 2 sections) will be installed onto the Foundation.
4. The WTG nacelle and hub with three blades will then be installed onto the tower.
5. The cables will then be terminated at the WTG switch gear, tested and energised and
the WTG commissioned using grid power from onshore via the Export Cables.
The items that will be decommissioned will be as follows:
• The WTG including three blades;
• The WTG tower in two sections;
• The Transition Piece and all attachments, such as 1-tubes, boat fenders, access
ladder systems and access platform;
• The monopile foundation cut at 2m below seabed level at the bottom of any scour hole;
and
• The sections of Interarray Cable which emanate away from the WTG structures from
the exit point of the bellmouth on the l-tube to the touchdown point on the seabed and
out further to the transition point where cable burial starts in the seabed. This will
MAY 2008 Page 4.2 of 4.4
• typically be a section of cable 10-25m long. All cables left within the l-tubes will also be
recovered.
It should be noted that any scour holes that have formed at the base of the pile foundations will fill
naturally within a few days after the removal of the pile.
FIGURE 4.1 GENERAL ARRANGEMENT OF WTG STRUCTURE
MAY 2008 Page 4.3 of 4.4
4.3 S U B S E A C A B L E S
The term 'subsea cables' refers to both the Export (132kV) Cables and the Interarray (33kV)
Cables.
4.3.1 Export Cables
There are two Export Cables which connect the Thanet project to the shore. Their positions are
illustrated in Figure 3.2. They will be buried to 1-2m beneath the seabed depending on localised
seabed conditions.
The Export Cables will for the most part be left buried in situ and will not form part of the
decommissioning works. The exceptions being the sections of cable close to the Offshore
Substation and at the landfall (refer to Sections 4.1 and 4.2).
The sections left in place will also include:
• The sections of cable which cross the in-service PEC and Tangerine
telecommunication cables; and
• The section of Export Cables through the intertidal zone.
4.3.2 Interarray Cables
The only sections of Interarray Cables which will be removed are those 10 to 20m sections close
to each of the WTGs and those close to the Offshore Substation, as identified in Section 4.2.
4.3.3 External Cable Protection
In addition to the removal of cable sections as identified in Sections 4.3.1 and 4.3.2 above, any
external cable protection will also be recovered. This is expected to be concrete mattresses used
to protect surface laid sections of cable which are found at the cable crossing locations and
where cables exit J/l tubes before being buried into the seabed.
An assessment will be made immediately prior to decommissioning to establish if the removal of
this external cable protection would potentially cause more damage to the environment. It is
possible that these features may have formed artificial reefs and as such may be better left in
place and undisturbed. Absent of any such assessment result, this Decommissioning Plan
assumes that the external cable protection will be recovered.
Only where the mattresses are removed will the cables underlying them also be removed.
MAY 2008 Page 4.4 of 4.4
5. DESCRIPTION OF PROPOSED DECOMMISSIONING MEASURES
This section of the Decommissioning Plan describes the measures to be taken for the
decommissioning of the Thanet Offshore Wind Farm (Thanet) project.
5.1 PLAN O F W O R K S A N D I N T E G R A T I O N
A detailed plan of work will be prepared for the decommissioning works at least one year ahead
of the proposed decommissioning date and will incorporate the results of a detailed and recent
EIA on the subject. The process supporting the EIA will include pre-decommissioning surveys to
standards set under MGN 275 (e.g. IHO Order 1 standard multi-beam bathymetry). The plan of
work will include detailed Method Statements together with project specific hazard and risk
assessments. TOW will also liaise with other developers in the Thames Estuary SEA area to
ensure that if potential synergies are available for decommissioning facilities at the same time,
then such synergies are exploited.
5.2 P R O P O S E D M E T H O D O F R E M O V A L
The detailed Method Statement for the Decommissioning Plan will cover:
• Health and safety considerations;
• Best Practicable Environmental Option (BPEO), the option which provides the most
benefit or least damage to the environment as a whole in both the long and short term,
at an acceptable cost; and
• Safety of surface and subsurface navigation.
For the decommissioning of the wind farm components which have to be removed, the installation
methodology is generally reversed. As in Section 4, the proposed methodology of removal has
been split for the three separate areas as follows:
1. Offshore Substation;
2. Offshore WTG Structures; and
3. Subsea Cables.
MAY 2008 Page 5.1 of 5.4
5.2.1 Offshore Substation
The Offshore Substation will be removed using an offshore Heavy Lift Vessel (HLV). The HLV
will lift major components such as Topside modules and Topside structure onto an adjacent
transport barge. The various components will then be transported back to the decommissioning
port, where a quayside crane will lift the components onto the quayside where they will be
processed for recycling or disposal as appropriate. All decommissioning will have appropriate
hazard and risk assessments completed to ensure risks to personnel were minimised and
handling of any hazardous materials carefully controlled.
The Offshore Substation and piles will be removed in a similar fashion to that described above.
The piles will be cut at 2m below seabed level at the bottom of any scour holes that have formed.
If at all possible, remote cutting technologies will be utilised to minimise or exclude any diver
intervention for health and safety reasons. The cutting process will probably be a combination of
high pressure water with entrained grit to assist cutting.
An HLV will be required for the decommissioning of the Offshore Substation, as the weight of the
various components will be higher than those encountered with the decommissioning of the
offshore WTGs.
5.2.2 Offshore WTG Structures
The sequence for the decommissioning of each of the WTG structures will generally be as
follows:
1. A row or 'string' of WTGs will be de-energised via the Offshore Substation to facilitate
the first stage in decommissioning the WTGs.
2. Each WTG will have its hub and blades locked in position in a 'Y' arrangement to
enable safe removal.
3. A jack-up crane barge will be mobilised to the wind farm, which will jack-up at each
WTG position in order to lift and remove all redundant components from each WTG.
4. The Interarray Cables will be cut at the start of cable burial into the seabed and the cut
length will then be removed from the WTG switchgear, pulled through the I-tube and
lifted onto the jack-up barge.
5. The WTG blade at the base of the 'Y' will then be unbolted and lifted onto the jack-up
barge to assist in the subsequent removal of the WTG nacelle.
6. The WTG nacelle with its locked hub and two blades will then be unbolted from the
tower and lifted onto the jack-up barge.
MAY 2008 Page 5.2 of 5.4
7. The WTG tower will then be unbolted and removed. The WTG tower will be removed in
one piece for speed of dismantling.
8. The piles will then be cut at 2m below seabed level. The cutting process is likely to be
the same as described for the Offshore Substation piles in Section 5.2.1 above. The
cut Monopile and Transition Piece will then be removed by the crane in a single piece.
9. All of the cut components will be transported to the decommissioning port for
processing. As many components as possible will be recycled, others will be safely
disposed of. Because the structures are mainly constructed from steel, there will be a
very high percentage of recycled materials. The transportation process will be by either
the main jack-up barge completing the lifts or a support transport barge may be
utilised.
10. This sequence will be repeated for all WTGs.
5.2.3 Offshore Cables
The Offshore Cables that are planned to be removed will be removed as part of the operations
described in 5.2.1 and 5.2.2.
5.3 PROPOSED WASTE MANAGEMENT SOLUTIONS
Waste management will be carried out in accordance with all relevant legislation at the time. It is
intended that the vast majority of all elements of the offshore wind farm will be taken back to land
for reuse and recycling.
5.4 DETAILS OF ANY ITEMS WHICH MAY BE LEFT IN SITU OFFSHORE
FOLLOWING DECOMMISSIONING
As described in the previous sections, it is proposed to leave major sections of offshore cables
and the embedded piles in the seabed. The basis of this decision is that the item in question
meets at least one of the four situations in which (based on the IMO standards) non-removal or
partial removal may be considered.
The four situations are where:
1. The installation or structure will serve a new use, whether for renewable energy
generation or for another purpose, such as enhancement of a living resource (provided
it would not be detrimental to other aims, such as conservation);
2. Entire removal would involve an unacceptable risk to personnel;
MAY 2008 Page 5.3 of 5.4
3. Entire removal would involve an unacceptable risk to the marine environment; or Entire
removal would involve extreme costs.
The primary reason for leaving cables buried and embedded piles in the seabed is that their
removal is likely to cause a major impact to the environment and may require significant and
dangerous diver involvement. However, all four of the above situations are expected to be
relevant and influential in justifying that the proposed exclusions from recovery. For instance, the
complete recovery of all of the pile structures would entail a major excavation of the seabed that
would be very costly and hugely damaging to the environment in the area.
MAY 2008 Page 5.4 of 5.4
6. ENVIRONMENTAL IMPACT ASSESSMENT
The original EIA for this project included an assessment of the decommissioning scope
envisaged under this plan. Appendix 1 summarises the findings of this EIA.
A further Environmental Impact Assessment (EIA) will be undertaken to assess the potential
effects of the proposed decommissioning measures on the environment. This will involve a set of
pre-decommissioning surveys that will, amongst other things, fully determine the extent of
Sabellaria Spinulosa in the area. An outline version of the Decommissioning Environmental
Statement (ES) will be prepared within one year of the completion of the construction of the
Thanet project. This outline version will then be developed into a more detailed document two
years prior to the start of decommissioning works when more certainty exists on the scope
required to match the legislation in place at that time.
The EIA will use the analysis already undertaken for the wider EIA undertaken prior to consent of
the installation of the wind farm. The Decommissioning ES will then be reviewed towards the end
of the life of the installation, when a final review of the decommissioning programme is
undertaken to finalise the decommissioning measures proposed.
The final EIA will aim to:
• Identify and assess potential impacts on the environment, including exposure to
contaminants associated with the installation other biological impacts arising from
physical effects, conflicts with the conservation of specifies, with the protection of their
habitats;
• Identify and assess potential impacts on amenities, the activities of communities (such
as Sabellaria) and on future uses of the environment;
• Describe the measures envisaged to avoid, reduce and, if possible, remedy any
significant adverse effects indicated (such as leaving some buried items in situ); and
• Identify and assess the effect on marine life caused by the removal of the WTG
foundation, which may now offer shelter or support to fishes or plant life by acting as
artificial reefs (such as the concrete mattresses).
MAY 2008 Page 6.1 of 6.1
7. CONSULTATIONS WITH INTERESTED PARTIES
The full project ES issued in November 2005 included a description of the decommissioning
proposals outlined in this document. The ES also included a review of the proposed
Decommissioning Plan. The document was consulted on widely, at both national and regional
levels, and included all the stakeholders that have been involved in assessing this
Decommissioning Plan. No objections were received by the BERR in respect of the
decommissioning proposals and the BERR licensing team already has full copies of all
correspondence from the consultees involved.
The final decommissioning programme will describe any additional consultation process
proposed by TOW. When all consultations have been completed, a summary of the consultations
undertaken with interested parties will be prepared a year before the decommissioning activity is
proposed to commence. This report will explain the extent to which such views have been taken
into account in the programme and scope of work (e.g. the mitigation of damage to Sabellaria
reefs from the jack-up barges needed to carry out the works). Relevant correspondence will be
annexed to the programme and, if appropriate, information will be included within the ES
described in Section 6 above.
MAY 2008 Page 7.1 of 7.1
8. COSTS
In developing a capital cost for the Thanet project, TOW has made an estimate for the future
decommissioning for the offshore wind farm. More detailed information on this and other costs is
set out in the Cashflow Forecast attached at Appendix 2. TOW will develop a more detailed cost
estimate for the decommissioning works once the construction activities are completed. This will
cover the following subject areas:
• Design of removal techniques;
• Health, safety and environmental constraints
• Optimum removal techniques for major items;
• Logistics;
• Transportation and off-loading;
• Management and disposal of materials onshore;
• Survey requirements to confirm decommissioning works complete; and
• Potential post-decommissioning surveys and monitoring (if required).
As no additional equipment will be deployed during the decommissioning activities the vast
majority of the costs involved consist of the hire cost for the vessels and equipment used to
remove the structures. These costs will typically involve a mobilisation fee of around £1,000,000
and then a charge for each day of operation of typically £50,000 to £75,000 per day at current
prices. The current indications on costs are broadly in line with the BERR estimates of net
decommissioning costs of around £40,000 per MW indicating a net decommissioning cost for the
Thanet project of £12m.
MAY 2008 Page 8.1 of 8.1
9. FINANCIAL SECURITY
Thanet Offshore Wind Limited (TOW) is a Special Purpose Vehicle (SPV) designed solely for the
operation of the Thanet project. All consents, licences, loans, assets and revenues involved in the
Thanet project are owned by TOW. TOW will provide adequate Financial Security to cover its
obligations under this Decommissioning Plan without recourse to any of its shareholders, who
may themselves change from time to time over the project life.
It is understood that an industry-wide Trust may be set up to cover all participating developers
monitoring obligations post-decommissioning plus any other obligations that may occur after
decommissioning. Subject to a review of the details, TOW would intend to participate in such a
scheme should it be established.
It is fully recognised that TOW itself will have to provide funds to cover the main decommissioning
activity that is expected to occur at the end of the 40 year lease with The Crown Estate and
acknowledged that, should the WTGs not be replanted, decommissioning may actually take place
after approximately 20 years.
TOW would prefer to secure its decommissioning obligations through a mid-life accrual fund, paid
into a dedicated and restricted Escrow account. If this was acceptable, TOW would commit one
tenth of the expected net decommissioning costs to the escrow account following the tenth year
of operation tenth year of operation beginning 1st January 2010, the first year of complete
operation following commissioning (currently expected to be approx £1.2m pa). In the event of a
replanting of the WTGs at Year 20 TOW would request that these funds were released back to
TOW and that a separate accrual is started again on the same principles at Year 30.
This is a sensible and practical method for ensuring that the decommissioning obligations are met
and does not involve excessive administrative burden. The financial strength of a renewable
energy project late in its operational life (compared to an Oil or Gas activity that depletes over
time) is such that decommissioning obligations can be met from operational cash flows as
evidenced below.
TOW is in the process of raising £500m of funds in order to construct the Thanet project. These
funding arrangements will be flexible enough to cope with the provision of secured funds for
decommissioning envisaged as £12m. Expected net annual revenues from the project, using the
current price for electricity and ROCs, range from £44,220,424 in 2009 part way through which
the project will be commissioned, through to £187,120,556 in 2029, for the approx 1 TWh of
annual output expected (P50 case). The cash requirements to fund the decommissioning
obligation are already modelled by the Lenders at £1.2m pa following the tenth complete year of
operation (2020) and rank above any debt repayment. Sums reserved for decommissioning are
provided for in the 'Opex' Section of the Cashflow Forecast at Appendix 2. It can be clearly seen
that TOW will easily be able to fulfil its obligations under this Decommissioning Plan whichever
Security arrangement is preferred.
MAY 2008 Page 9.1 of 9.2
TOW has been advised however that the preferred mid-life accrual fund proposal may not meet
the BERR's requirements because TOW is a SPV If this proves to be the case then as an
alternative TOW would meet its obligations through either a Bond or Letter of Credit structure
which would ramp up from 2020 by the amounts as described above.
MAY 2008 Page 9.2 of 9.2
10. S C H E D U L E
A full EIA will be commissioned two years ahead of the proposed decommissioning period.
A detailed schedule of the decommissioning works will then be prepared a year before the start of
the works taking onboard the results of the EIA and its consultation process. Such schedules will
be forwarded for BERR review and approval.
The schedules will clearly map out the sequence of decommissioning activities, providing detail
for the offshore removal works. It is expected that each WTG will take on average two (2) days to
decommission, remove and load onto a barge for transport to a shore facility, after taking weather
downtime into consideration. The Offshore Substation is expected to take up to three (3) weeks to
decommission, remove and load onto a barge for transport to shore for recycling.
TOW considers that the main offshore decommissioning work could be completed in an extended
single summer season of working of up to nine (9) months. This will probably required 24 hour
working and will also involve a significant element of pre-planning and advance preparation works
as described above.
MAY 2008 Page 10.1 of 10.1
11 . PROJECT MANAGEMENT AND VERIFICATION
The final Decommissioning Plan will provide information on how TOW will manage the
implementation of the decommissioning works and also provide assurance to the BERR
concerning progress and compliance.
The project management of the decommissioning works will be undertaken with the same rigor as
the original installation works. TOW envisages a single main contractor for the decommissioning
work and will also appoint an experienced and highly qualified project management team to
ensure the decommissioning work proceeds to schedule and in accordance with the requirements
of the Decommissioning Plan.
MAY 2008 Page 11.1 of 11.1
12. SEABED CLEARANCE
To demonstrate that the site has been cleared following the decommissioning works, a full
subsea seabed survey will be undertaken with independent monitoring through onboard
observers, possibly drawn from the local fishing community. This survey will cover areas of at
least 500 metres around each and every structure and the results will be submitted to the BERR.
The main purpose of this survey will be to confirm that the full scope of the decommissioning
works has been completed. However, the same survey will be used to enable identification and
having regard to any declared Archaeological Exclusion Zones subsequent recovery of any rogue
debris located on the seabed, which may have arisen from the activities and may pose a risk to
navigation, other users of the sea or the marine environment. Where rogue debris is identified
and recovered the area affected will be resurveyed with the independent monitoring as proposed
above.
MAY 2008 Page 12.1 of 12.1
13. RESTORATION OF THE SITE
Using the pre-construction survey data, the site will be restored as far as possible and desirable
to the condition that it was prior to the original construction of the installation. However, as the
original method of installation for both the WTG foundations and subsea cables were designed
with due regard to cause minimum disturbance during their initial installation, TOW does not
envisage, or plan, to undertake any specific underwater intervention works to restore any seabed
conditions.
TOW does not intend to fill any scour holes that have formed around the base of the piled
foundations. TOW considers that the scour holes will fill naturally after the removal of the piles
within a few days and that operations required to fill the holes would be disruptive to marine life
and introduce significant foreign materials into the local seabed.
MAY 2008 Page 13.1 of 13.1
14. POST DECOMMISSIONING MONITORING, MAINTENANCE AND
MANAGEMENT OF THE SITE
A post-decommissioning monitoring and maintenance plan will be included as part of the EIA
process that will take place ahead of the decommissioning of the facility. This will establish what
(if any) future management of the Thanet site will be required and whether this can be carried out
as part of an industry-wide programme. In the absence of these final proposals, TOW will assume
that an annual survey of the site will be required for up to three years following the end of the
planned decommissioning activity. Should any items that might be left in-situ become uncovered
during this period then TOW will recover such items and recycle them onshore. The nature of this
annual survey will be the same as the Seabed Clearance survey (see Section 11) and the results
will be provided to the BERR.
MAY 2008 Page 14.1 of 14.1
15. SUPPORTING STUDIES
Any supporting studies or investigations which are undertaken in support of future
decommissioning plans will be included as annexes to the Decommissioning Plan. This plan
includes as an Annex the results of the Environmental Impact Assessment conducted in 2005 in
relation to this plan.
MAY 2008 Page 15.1 of 15.1
APPENDIX 1
Environmental Statement Summary
[Attached under separate cover.]
MAY 2008 Page 16.1 of 16.1