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East Anglia ONE Offshore Windfarm – HVAC Option Assessment Environmental Report
East Anglia ONE Offshore Windfarm May, 2015
Environmental Report
EA ONE – Environmental Report Page 2
Table of contents 1 Introduction 1
2 Alternative Project Description 2
3 Consultation 5
4 Methodology 5
5 Screening 5 5.1 Introduction 5 5.2 Screening of offshore topics 6 5.2.1 Identification of changes and effects relevant to the offshore assessment 6 5.3 Screening of Onshore Topics 7 5.3.1 Identification of changes and effects relevant to the onshore assessment 7
6 Updated Assessments 14 6.1 Introduction 14 6.2 Traffic and Transport 14 6.2.1 Introduction 14 6.2.2 Methodology 14 6.2.3 Updated assessment 17 6.2.4 Conclusions 20 6.3 Landscape and Visual Impact 20 6.3.1 Introduction 20 6.3.2 Methodology 21 6.3.3 Summary of the original assessment 22 6.3.4 Updated assessment 23 6.3.5 Conclusions 26
7 Conclusions 26
8 References 27
Table of tables Table 2.1 Proposed changes to the project description to include the option for an up to 750MW windfarm with HVAC
transmission infrastructure ......................................................................................................................................................... 3 Table 5.1 Offshore impact assessment screening ............................................................................................................... 8 Table 5.2 Onshore impact assessment screening ............................................................................................................. 11 Table 5.3 Scheme wide impact assessment screening ..................................................................................................... 13 Table 6.1 Transport parameters ........................................................................................................................................ 15 Table 6.2 Cable and duct pipe requirements for the consented and alternative projects .................................................. 19 Table 6.3 Key proposed changes to the onshore converter station/substation parameters .............................................. 21 Table 6.4 Analysis of viewpoint photomontages ................................................................................................................ 24
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Table of plates Plate 2.1 Illustrative trench swathe diagram ....................................................................................................................... 2 Plate 6.1 Detailed breakdown of HGV demand for each cable route section .................................................................... 18
Appendices
Appendix 1 Landscape and Visual Impact Assessment figures…………………........………………………………………29
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Summary
The East Anglia ONE Offshore Windfarm Development Consent Order (DCO) grants the construction and operation of an
offshore windfarm with a gross output capacity of up to 1,200MW, consisting of up to 240 wind turbines and associated high
voltage direct current (HVDC) electrical transmission infrastructure.
Following the award of the DCO to East Anglia ONE, and participation in the first Allocation Round of the Contract for
Difference (CfD) regime, East Anglia ONE was awarded a CfD for 714MW of capacity. A project with this level of capacity
would need to connect to the national transmission network through high voltage alternating current (HVAC) rather than
HVDC technology. As such, this smaller project requires a number of limited changes to the configuration of the transmission
infrastructure offshore and onshore.
East Anglia ONE Limited is therefore seeking to vary the DCO to include an alternative option to construct an up to 750MW
windfarm (an allowance over 714MW to account for transmission losses) with a HVAC transmission system. The option to
construct the consented HVDC project with a capacity of up to 1,200MW will be retained within the DCO.
This Environmental Report demonstrates that, for the purpose of the Infrastructure Planning (Changes to, and Revocation of,
Development Consent Orders) Regulations 2011 (as amended), the potential impacts associated with the proposed changes
are in all cases no greater (and would in many cases be less) than those previously assessed for the consented project, and
therefore the changes can be described as non-material for the purpose of the Regulations. The proposed non-material
amendments do not have any impact on the provisions in the DCO relating to future projects.
All topics and potential impacts were screened against the proposed changes to the project design. This involved a
consideration of the effects of the proposed changes and whether these effects could result in a different level of impact to
that identified in the existing assessment. Where there is a clear case that the level of significance would be unchanged or
reduced (e.g. due to a decrease in the spatial footprint of the project), these topics have been screened out from further
assessment. Where further analysis was required to determine whether the significance of the impact would be unchanged
or reduced, an updated assessment is provided.
With respect to both the offshore and onshore environment, it is concluded that the worst case scenario in all instances is
unchanged and the potential impacts associated with the proposed changes to the project design are of no greater
significance than those identified in the existing assessment (comprising the Environmental Statement, Supplementary
Environmental Information and ornithological technical assessments). Offshore, this is primarily on account of the fact that
no changes are proposed to the boundaries of the windfarm or the offshore export cable corridor, whilst there would be a
reduction in the number of wind turbines, offshore platforms and export cables installed.
Onshore, this is due to the fact that no changes are proposed to the boundaries of the onshore cable corridor (more cables
would be installed in the same number of trenches), or of the onshore substation. The maximum height of the buildings at
the substation site is reduced, none of the footprints of the buildings will be greater in size than those considered in the
existing assessment and there would be only a slight increase in the height of outdoor equipment at the substation. Certain
aspects of the assessments for traffic and transport, and landscape and visual have been updated in order to provide greater
certainty with respect to these conclusions. No change in the significance of impacts is predicted for either topic following the
updated assessments.
It is therefore considered that the proposed changes would constitute non-material amendments for the purposes of the
Regulations.
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1 Introduction 1. East Anglia ONE Limited (EAOL) submitted an application for a Development Consent Order (DCO) for the East Anglia ONE
Offshore Windfarm in November 2012. Consent was granted by the Secretary of State in June 2013. The DCO granted
consent for the development of an offshore windfarm with a gross output capacity of up to 1,200MW (1.2GW), consisting of
up to 240 wind turbines (off the coast of Suffolk) and associated high voltage direct current (HVDC) electrical transmission
infrastructure offshore and onshore including inter-array cabling, offshore collector/converter stations, offshore export cables,
onshore export cables and an onshore converter station at Bramford in Suffolk (“the consented project”).
2. Following the award of the DCO to East Anglia ONE, and participation in the first Allocation Round of the Contract for
Difference (CfD) regime, East Anglia ONE was awarded a CfD for 714MW of capacity on 26th
February 2015. A project with
this level of capacity would need to connect to the national transmission network through high voltage alternating current
(HVAC) rather than HVDC technology. As such, this smaller project requires a number of limited changes to the
configuration of the transmission infrastructure offshore and onshore.
3. East Anglia ONE Limited is therefore seeking to vary the DCO to include an alternative option to construct an up to 750MW
windfarm (an allowance over 714MW to account for transmission losses1) with a HVAC transmission system (“the alternative
project”). All changes would fall within the existing Order Limits of the consented project. The option to construct the
consented HVDC project with a capacity of up to 1.2GW will be retained within the DCO.
4. This Environmental Report is submitted in support of the application to vary the DCO under the Infrastructure Planning
(Changes to, and Revocation of, Development Consent Orders) Regulations 2011 (the Regulations) as amended by the
Consequential Amendments Regulations 2012. It provides an overview of the potential impacts of the alternative project and
compares these to the conclusions reached in the original Environmental Impact Assessment (EIA) (East Anglia Offshore
Wind Limited, 2012), Supplementary Environmental Information (SEI) (East Anglia Offshore Wind Limited, 2013) and the
ornithological assessments submitted during the East Anglia ONE examination process (collectively referred to as “the
existing assessment”). It demonstrates that the potential impacts associated with the proposed changes are no greater (and
would in many cases be less) than those previously assessed for the consented project, and that the proposed changes can
therefore be described as non-material for the purpose of Part 1 of the Regulations. Additionally, the proposed non-material
amendments do not have any impact on the provisions in the DCO relating to future projects.
5. The report is supported by the results of an environmental screening exercise (Section 5) and updated assessments for
traffic and transport, and landscape and visual (Section 6). Drawings of the two scenarios that have been considered in the
updated landscape and visual assessment, as well as the viewpoint locations and associated photomontages, are presented
in Appendix 1. These are:
• Figure 1: HVAC Substation Indicative Layout: Scenario 1
• Figure 2: HVAC Substation Indicative Layout:Scenario 2
• Figure 3: Viewpoint locations
• Figure 4: HVAC Substation Photomontage Viewpoint 3 (Summer): Flowton
• Figure 5: HVAC Substation Photomontage Viewpoint 3 (Winter): Flowton
• Figure 6: HVAC Substation Photomontage Viewpoint 5 (Summer): Canes Farm
• Figure 7: HVAC Substation Photomontage Viewpoint 5 (Winter): Canes Farm
• Figure 8: HVAC Substation Photomontage Viewpoint 10 (Summer): Fidgeons Farm
• Figure 9: HVAC Substation Photomontage Viewpoint 10 (Winter): Fidgeons Farm
• Figure 10: HVAC Substation Photomontage Viewpoint 15: Church Hill
1 Referred to as ‘overplanting’, this allows the Project to be optimised for maximum efficiency taking into account factors such as electrical
losses during transmission.
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2 Alternative Project Description 1. As described above, an alternative option to construct an up to 750MW windfarm with HVAC transmission would require a
number of limited changes to the configuration of transmission infrastructure, alongside the corresponding reduction in the
number of wind turbines. It is important to note that the proposed non-material amendments will not have any impact on the
provisions in the DCO relating to future projects.
2. Offshore the changes would be as follows:
• The maximum number of wind turbines is reduced from 240 to 150.
• The maximum total number of offshore platforms is reduced from five platforms (three HVAC collector stations and two
HVDC converter stations) to two platforms (HVAC substations).
• The two HVAC substations will be the same size as the originally proposed HVDC converter stations (60m height, 75m
length and 120m width) but could be located anywhere within the windfarm area, rather than constrained to the western
part of the site as is currently the case).
• There would be up to two 400kV HVAC offshore export cables rather than up to four 600kV HVDC offshore export
cables.
3. There are no proposed changes to the ducting arrangements for future projects. Onshore the changes relate only to East
Anglia ONE infrastructure. These changes would be as follows:
• There would be up to six 400kV HVAC onshore export cables rather than up to four 600kV HVDC onshore export cables.
The six cables would be laid in two circuits of three cables, in two separate trenches, within the original working width of
the cable corridor. There would be no change to the total number of onshore trenches. See illustrative trench swathe
diagram below (Plate 2.1).
• An HVAC onshore substation would be required instead of the currently specified HVDC converter station. The
substation would be contained within the specified footprint of the consented HVDC compound. There would be a small
increase in the maximum height of outdoor electrical equipment from 10m to 15m, in order to cater for the different
technical requirements of HVAC equipment.
• Two extra lengths of duct would be required at each horizontal directional drilling (HDD) crossing due to the increase in
the number of onshore export cables. These would be accommodated within the existing Order Limits.
• There would be a reduced number of jointing bays (57 bays per cable were included in the existing assessment for four
cables, for the alternative project there would be 57 bays for each of the two circuits).
Plate 2.1 Illustrative trench swathe diagram
4. Full details of all of the proposed changes to the project description are given in Table 2.1.
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Table 2.1 Proposed changes to the project description to include the option for an up to 750MW windfarm with HVAC transmission infrastructure
Parameter Consented up to 1.2GW HVDC project Alternative up to 750MW HVAC
project
Offshore
Number and size of platforms Up to three HVAC collector station platforms
(40 x 30m x 60m)
Up to two HVDC converter station platforms
(120 x 75m x 60m)
Up to two HVAC substation platforms (120 x
75m x 60m)
No HVDC converter station platforms
Number of offshore wind
turbines
1,200MW comprising a maximum of 240
offshore wind turbines
750MW comprising a maximum of 150
offshore wind turbines
Maximum scour protection
(generation assets)
3.5km2 No change
Maximum scour protection
(transmission assets)
0.029km2 No change
Maximum inert material
disposed (generation assets)
5,603,500m3 No change
Maximum inert material
disposed (transmission assets)
245,000m3 No change
Offshore export cables Up to 4 x 100km 600kV HVDC export cables Up to 2 x 100km 400kV HVAC export cables
Cable separation 200m between cables pairs, 50m between
cables in pairs, 250m outer protection area on
either side (800m corridor in total).
Up to four trenches
50m between cables, 250m outer protection
area on either side (550m corridor in total).
Up to two trenches
Cable protection Cables buried where practical, external
protection at cable crossings
40 export cable crossings, five inter-array
cable crossings
No change
20 export cable crossings, five inter-array
cable crossings
Landfall
Cable installation Method: HDD
Working width: 160m
No change
Transition joint bay parameters Maximum number: 12, plus two smaller boxes
for earthing and fibre optics
Maximum dimensions: 5m x 10m x 5m, 1m x
1m x 5m
Maximum number: No change
Maximum dimensions: No change
Onshore export cables
Cable number and dimensions Up to four onshore HVDC export cables and
fibre optics cables, plus eight ducts for future
projects
Cable length: approximately 37km
Cable rating: 600kV
Trenches: Six trenches in total, for EA ONE
two trenches with two power cables will be
Up to six onshore HVAC export cables and
fibre optics cables, plus eight ducts for
future projects
Cable length: approximately 37km
Cable rating: 400kV
Trenches: No change: Six trenches in total,
for EA ONE two trenches with three power
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Parameter Consented up to 1.2GW HVDC project Alternative up to 750MW HVAC
project
installed cables making two circuits
Working width 55m swathe for the majority of the cable route.
Between 110m and 160m at HDD locations.
Special case pinch points exist at 15 and 13m
No change
Cable burial depth Typically 1.2m below ground level
Drilling up to 25m may be required for Deben
crossing
No change
HDD compound size 2500m2 at each drill rig and exit site No change
Jointing bay parameters Maximum number: 57 for each of four cables
(assuming one every 500m) (total 228)
Maximum dimensions: 10m x 5m x 5m
Maximum number: 57 for each of two
circuits (total 114)
Maximum dimensions: No change
Onshore converter station/substation
Number and size of onshore
installations
One HVDC converter station
Maximum compound dimensions: 150m x
190m
Maximum building dimensions:
130m x 85m x 25m
One HVAC substation
Maximum compound dimensions: No
change
The maximum building dimensions are
dependent on the balance of indoor and
outdoor equipment but will be less than the
original assessment. The maximum building
height will reduce from 25m to 21m (see
below)
Equipment height dimensions Primarily indoor but substantial amount of
outdoor electrical equipment
Maximum height of building: 25m
Maximum height of outdoor electrical
infrastructure: 10m (excluding compound
perimeter lightning protection and support
gantries: 25m)
Range: 70-90% outdoor, 10-30% indoor
Maximum height of building: 18m if mostly
outdoor equipment, 21m if mostly indoor
equipment
Maximum height of outdoor electrical
infrastructure: 15m (excluding compound
perimeter lightning protection and support
gantries: 18m)
Construction period Up to 44 weeks, potentially spread over two
years
Six days per week, 12 hour days2
No change
2 The assessment of traffic and transport impacts assumed a five day working week to provide a worst-case construction
traffic demand. See also requirement 23 of the DCO.
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3 Consultation 1. EAOL has conducted a programme of informal pre-application consultation in order to brief stakeholders on the nature of the
proposed DCO amendment and the intended approach to the accompanying environmental assessment (this report). This
has included the following:
• Initial briefing meetings for stakeholders (April & May 2015), including Local Planning Authorities, the Environment
Agency, Natural England, the Marine Management Organisation (MMO) and Historic England;
• Draft environmental report submitted to the same stakeholders for review (two week consultation period); and
• Feedback meetings – with above, May 2015.
2. The outcome of the consultation process with each stakeholder is recorded in letters submitted with the variation application
alongside this report.
4 Methodology 1. All topics assessed in relation to the consented project were considered in terms of the alternative project description as set
out in Section 2. The following steps were undertaken:
• All topics and potential impacts as set out in the existing assessment were screened against the parameters of the
alternative project description. This involved a consideration of the environmental effects of the proposed changes and
whether these effects could result in a different level of impact to that identified in the existing assessment.
• Where there was a clear case that the significance of the impact would be unchanged or reduced (e.g. due to a
decrease in the spatial footprint of the project), these topics were screened out from further assessment. The outcome
of the screening assessment is presented in Section 5 (Tables 5.1 to 5.3).
• Where further analysis was required to determine whether the significance of the impact would be unchanged or
reduced, updated assessments have been provided. These assessments are presented in Section 6.
• Where the significance of the impact would be unchanged or reduced from the East Anglia ONE Windfarm alone, it is
considered that the significance of any cumulative impacts would also be unchanged or reduced.
• Where the outcome of the screening or updated assessments confirmed that the significance of the impact would be
unchanged or reduced, the associated changes are considered to constitute non-material amendments for the purposes
of the Regulations.
5 Screening 5.1 Introduction
1. Tables 5.1 to 5.3 summarise the results of the screening exercise on a topic by topic basis. As described in Section 4,
topics have been screened out from further assessment where it is clear that the level of impact would be unchanged or
reduced from that described in the existing assessment. Where this is not the case, updated assessments are presented in
Section 6.
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5.2 Screening of offshore topics
5.2.1 Identification of changes and effects relevant to the offshore assessment
2. The proposed changes to the project description (Section 2) that are relevant to the assessment of offshore topics are as
follows:
• The maximum number of wind turbines is reduced;
• The maximum number of offshore platforms is reduced (the maximum size remains the same as the consented HVDC
converter stations);
• The maximum number (and therefore total length) of interconnector cables is reduced;
• The maximum number (and therefore total length) of export cables is reduced;
• The maximum number of cable crossings is reduced; and
• The export cables will be HVAC rather than HVDC.
3. The option to build the two HVAC substations within either the Work No. 1 or the Work No. 2 areas as described in the DCO
is screened out from further consideration on account of the following:
• The DCO currently allows up to three smaller HVAC collector stations of 60m height, 30m length and 40m width within
the Work No. 1 area;
• The two proposed HVAC substations will be no greater than the maximum dimensions of the two consented HVDC
converter stations that are permitted within the Work No. 2 area;
• If the larger HVAC substations are built, any further HVAC substations or HVDC converter stations would be excluded;
and
• None of the existing assessments make assumptions with respect to the exact location of any offshore platforms, which
will only be confirmed as part of the detailed design process nearer the time of construction. Assessments are either
based on a worst case seabed footprint (which is reduced through the reduction in the total number of platforms from five
to two) or, with respect to the risk of a vessel colliding with a structure (termed an allision), on the assumption that all
structures would be located on the perimeter of the windfarm array.
4. Note that there are no changes proposed to the windfarm boundary or the boundary of the offshore export cable corridor.
5. As a consequence of the proposed works described above, the following paragraphs set out the potential changes to the
assessed environmental effects for offshore topics during the construction, operation and decommissioning phases. Whether
these effects could result in a different level of impact to that identified in the existing assessment is considered in Tables 5.1
and 5.3.
Construction
• Reduced footprint of seabed disturbance from installation of cables and foundations (including any associated cable
crossings, scour protection and seabed preparation);
• Reduced volume of suspended sediments from construction work and of the associated effects on marine ecology and
other sensitive receptors;
• Reduced level of disturbance from the generally lower levels of construction activity on site, such as construction
vessels; and
• Reduced level of disturbance from the lower maximum number of piling events required to install foundations (depending
on the selected foundation design).
Operation
• Reduced footprint of cables or foundations above seabed level (including any associated cable crossings and scour
protection) and of the associated effects on the physical environment such as scour processes;
• Reduced potential for electromagnetic field (EMF) effects of buried cables (the export cables will be HVAC rather than
HVDC) due to reduced cable length; and
• Reduced level of disturbance from the lower levels of maintenance activity on site, such as operation and maintenance
vessels.
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Decommissioning
• Reduced footprint of seabed disturbance from removal of cables or foundations (including any associated cable
crossings and scour protection);
• Reduced volume of suspended sediments from decommissioning work and of the associated effects on marine ecology
and other sensitive receptors; and
• Reduced level of disturbance from the generally lower levels of decommissioning activity on site, including vessels.
6. Since the type of effects anticipated during decommissioning are similar in nature to those described for construction,
references in the following tables to construction apply equally to the decommissioning phase, where relevant.
7. The outcome of the screening exercise carried out for offshore topics is presented in Table 5.1 below. In keeping with the
structure of the existing assessment, scheme wide topics, including seascape and visual effects, are presented in Table 5.3.
5.3 Screening of Onshore Topics
5.3.1 Identification of changes and effects relevant to the onshore assessment
8. The proposed changes to the project description (Section 2) that are relevant to the assessment of onshore topics are as
follows:
• Maximum number of offshore export cables coming into the landfall has decreased from four to two;
• Maximum number of onshore cables is increased from four to six, but the number of trenches remain as per the original
design (two trenches) and the Order Limits are unchanged;
• The onshore cables will be HVAC rather than HVDC;
• Two extra lengths of duct will be required at each HDD crossing, which will be accommodated within the existing working
width;
• Reduced number of jointing bays (existing assessment assumed 57 bays per cable and 4 cables, the alternative project
assumes 57 jointing bays per circuit and 2 circuits); and
• Maximum height of the substation building has decreased, but the potential maximum height of the outdoor electrical
equipment has increased slightly.
9. There are no changes proposed to the location of the landfall site or the onshore cable corridor, with the length of route and
location of route remaining as per the existing assessment. These also remain within the original Order Limits with the same
working width for the cable route (typically 55m).
10. As a consequence of the proposed works described above, there is limited potential for any changes to the assessed
environmental effects for the onshore topics. Exceptions include: the potential for an increase in heavy goods vehicle (HGV)
traffic during construction on account of the increased number of cables and ducts at HDD crossings; and potential for
changes to effects on landscape and visual receptors during operation on account of the increase in the maximum height of
the outdoor infrastructure (although the maximum height of the substation building has decreased).
11. With respect to EMF, the proposed electrical infrastructure for the East Anglia ONE offshore windfarm will comply with
Government policy and with UK exposure guidelines. The resultant electric and magnetic fields generated will be extremely
low, or negligible, and will fall well under the accepted UK guidelines on exposure levels.
12. The outcome of the screening exercise carried out for all onshore topics is presented in Tables 5.2 and 5.3 below.
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Table 5.1 Offshore impact assessment screening
EIA topic Change in project parameters
(as applicable to each topic)
Key changes in effect/s Change in impact significance Updated assessment (Y/N)
No = screened out
Marine Geology, Oceanography
and Physical Processes (ES
Chapter 6)
Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments during construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Less physical infrastructure –
reduced footprint on seabed and
in the water column
Reduced interaction with physical
infrastructure during operation
Marine Water Quality (ES
Chapter 7)
Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments during construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Benthic and Epibenthic
Environment (including Shellfish)
(ES Chapter 9)
Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments during construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Less physical infrastructure –
reduced footprint on seabed
Reduced footprint of direct and
indirect disturbance to the benthic
environment
Reduction in the number of
offshore cables
The export cables will be HVAC
rather than HVDC
Reduced potential for effects
related to EMF
As set out in Section 5.2.1, the
maximum number (and therefore
length) of interconnector cables
and export cables is reduced.
The maximum number of cable
crossings is also reduced.
Meanwhile, there is no change to
the proposed cable burial depth,
or to the external cable protection
at cable crossings. Consequently,
no change in impact significance
is anticipated.
N
Fish Ecology (ES Chapter 10) Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments during construction
Reduction in the magnitude of
effect, no change in impact
significance
N
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EIA topic Change in project parameters
(as applicable to each topic)
Key changes in effect/s Change in impact significance Updated assessment (Y/N)
No = screened out
Less physical infrastructure –
reduced footprint on seabed
Reduced footprint of direct and
indirect disturbance to the benthic
environment
Reduction in the number of
offshore cables
The export cables will be HVAC
rather than HVDC
Reduced potential for effects
related to EMF
As set out in Section 5.2.1, the
maximum number (and therefore
length) of interconnector cables
and export cables is reduced.
The maximum number of cable
crossings is also reduced.
Meanwhile, there is no change to
the proposed cable burial depth,
or to the external cable protection
at cable crossings. Consequently,
no change in impact significance
is anticipated.
N
Marine Mammals (ES Chapter
11)
Reduced installation activity due
to a reduced number of
foundations
Reduced disturbance from noise
due to a decrease in piling activity
Reduction in the magnitude of
effect, no change in impact
significance
N
Ornithology (Marine and Coastal)
(ES Chapter 12)
Reduced installation activity due
to a reduced number of cables
and foundations
Reduced disturbance and
displacement effects during
construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Reduced number of wind turbines
and offshore platforms
Reduced disturbance,
displacement, barrier effects and
collision risk during operation
Commercial Fisheries (ES
Chapter 13)
Reduced installation activity due
to a reduced number of cables
and foundations
Reduced interaction during
construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Reduced number of wind turbines
and offshore platforms
Reduced interaction during
operation
Shipping and Navigation (ES
Chapter 14)
Reduced installation activity due
to a reduced number of cables
and foundations
Reduced interaction during
construction
Reduction in the magnitude of
effect, no change in impact
significance
N
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EIA topic Change in project parameters
(as applicable to each topic)
Key changes in effect/s Change in impact significance Updated assessment (Y/N)
No = screened out
Reduced number of wind turbines
and offshore platforms
Reduced interaction during
operation
Aviation and MoD (ES Chapter
15)
Reduced number of wind turbines
and offshore platforms
The existing assessment
concluded that radar would not
be affected – no change
No change in impact significance N
Telecommunications and
Interference (ES Chapter 16)
Reduced number of wind turbines
and offshore platforms
Reduced effects on radar and
vessel Automatic Identification
Systems (AIS)
Reduction in the magnitude of
effect, no change in impact
significance
N
Archaeology and Cultural
Heritage (ES Chapter 17)
Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments during construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Less physical infrastructure –
reduced footprint on seabed
Reduced footprint of direct and
indirect disturbance
Infrastructure and Other Users
(ES Chapter 18)
Reduced installation activity due
to reduced number of cables and
foundations
Reduced re-suspension of
sediments and reduced
interaction with other users during
construction
Reduction in the magnitude of
effect, no change in impact
significance
N
Reduced number of wind turbines
and offshore platforms
Reduced interaction with other
users during operation
Airborne Noise (ES Chapter 19) Reduced number of wind turbines
and offshore platforms
Reduced levels of noise
disturbance due to a decrease in
construction and operation
activity
Reduction in the magnitude of
effect, no change in impact
significance
N
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Table 5.2 Onshore impact assessment screening
EIA topic Change in project parameters
(as applicable to each topic)
Key changes in effect/s Change in impact significance Updated assessment (Y/N)
No = screened out
Ground Conditions and
Contamination (ES Chapter 20)
Reduced number of jointing bays
along the cable route
Reduced construction activity and
footprint of disturbance
Reduction in the magnitude of
effect, no change in impact
significance
N
Air Quality (ES Chapter 21) Reduced number of jointing bays
along the cable route
Reduced construction activity
Reduction in the magnitude of
effect, no change in impact
significance
N
Increased number of onshore
cables
Potential for an increase in dust
and emissions from HGV traffic
during construction
Updated traffic and transport
assessment (see Section 6)
confirms worst case traffic flows
are unchanged, therefore no
change in impact significance
Y – see Section 6
Water Resources and Flood Risk
(ES Chapter 22)
Reduced number of jointing bays
along the cable route
Reduced construction activity and
footprint of disturbance
Reduction in the magnitude of
effect, no change in impact
significance
N
Land Use (ES Chapter 23) Reduced number of jointing bays
along the cable route
Reduced construction activity and
footprint of disturbance
Reduction in the magnitude of
effect, no change in impact
significance
N
The onshore cables will be HVAC
rather than HVDC
Potential change in EMF
properties of the buried onshore
cables
No change in impact significance
Ecology (ES Chapter 24) Reduced number of jointing bays
along the cable route
Reduced construction activity and
footprint of disturbance
Reduction in the magnitude of
effect, no change in impact
significance
N
Increased number of onshore
cables
Potential increase in duration of
HDD works at crossings, and
associated disturbance
Although there may be a slight
increase in the duration of HDD
works at each crossing, the
overall construction period is
unchanged. Any increase in
duration would be within the
worst case parameters of the
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EIA topic Change in project parameters
(as applicable to each topic)
Key changes in effect/s Change in impact significance Updated assessment (Y/N)
No = screened out
existing assessment and
consequently there will be no
change in impact significance.
Archaeology and Cultural
Heritage (ES Chapter 25)
Reduced number of jointing bays
along the cable route
Reduced construction activity and
footprint of disturbance
Reduction in the magnitude of
effect, no change in impact
significance
N
Noise and Vibration (ES Chapter
26)
Reduced number of jointing bays
along the cable route
Reduced construction activity
Reduction in the magnitude of
effect, no change in impact
significance during construction
N
Increased number of onshore
cables
Potential for an increase in noise
from HGV traffic during
construction
Updated traffic and transport
assessment (see Section 6)
confirms worst case traffic flows
are unchanged, therefore no
change in impact significance
Y – see Section 6
HVAC substation rather than
HVDC converter station
No change - noise generated at
the substation will not exceed
35dB LAeq, 5 min as measured at
nearby receptors, in line with
DCO requirements
No change in impact significance
during operation
N
Traffic and Transport (ES
Chapter 27)
Reduced number of jointing bays
along the cable route
Potential for an increase in HGV
traffic during construction on
account of the increased number
of cables
Updated assessment (see
Section 6) confirms no change in
impact significance
Y – see Section 6
Increased number of onshore
cables
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Table 5.3 Scheme wide impact assessment screening
EIA topic Change in project
parameters (as applicable
to each topic)
Key changes in effect/s Change in impact
significance
Updated assessment (Y/N)
No = screened out
Socio-economics (ES Chapter
28)
Reduced number of
turbines and offshore
platforms
Potential reduction in the levels of construction
and operation activity required to support the
project
Whilst a smaller project will result in fewer job
opportunities, the original EIA assumptions
were precautionary and more recent
engagement with the supply chain suggests
that the upper range for estimated jobs for a
750MW scheme overlaps with the lower range
for a 1,200MW scheme. In addition, similar to
the 1,200MW scheme, the 750MW scheme
would not lead to significant impacts or
residual effects at an East Anglia Region level,
although both schemes would provide minor
economic benefits.
No change to the commitment to implement a
skills strategy
No change in impact
significance
N
Seascape and Visual Impact (ES
Chapter 29)
Reduced number of wind
turbines and offshore
platforms
Reduction in construction and operation
activity and the associated seascape and
visual effects
Reduction in the
magnitude of effect, no
change in impact
significance
N
Landscape and Visual Impact
(ES Chapter 29)
Reduced maximum height
of buildings within the
substation compound
Potential changes to landscape receptors and
views of the onshore substation
Updated assessment (see
Section 6) confirms no
change in impact
significance
Y – see Section 6
Increase in height of the
outdoor electrical
equipment at the onshore
substation
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6 Updated Assessments 6.1 Introduction
1. Following the outcome of the screening process (Section 5), the following section presents the updated assessments that
have been undertaken for traffic and transport (Section 6.2), and landscape and visual (Section 6.3).
6.2 Traffic and Transport
6.2.1 Introduction
2. This section reviews the traffic and transport impacts presented in the existing assessment in context with the proposed
changes to the configuration of transmission infrastructure and a reduction in the number of wind turbines. As set out in
Section 1, the assessment of traffic and transport for the consented project included the submission of an ES and a
subsequent SEI.
3. Forecast changes in traffic flows resulting from the alternative project design changes are compared to the data presented in
the existing assessment to establish whether the assessed traffic and transport impacts will change.
4. The traffic terms used in this assessment are traffic flows, deliveries or movements. In the context of this report, traffic flow is
a general term that does not imply a specific volume, a delivery is a laden HGV, and a movement refers to the actual journey
being made. Therefore, a single delivery would result in two HGV movements, one each for arrival (laden) and departure
(empty).
6.2.2 Methodology
5. The assessment revisits the quantities of material and programme assumptions that underpinned the traffic forecasts,
identifies the level of contingency and assesses if the amendments resultant from the alternative project design can be
accommodated within those contingencies. If the changes can be accommodated in the contingencies, then it follows that
there will not be a change to the existing assessment.
6. Forecast traffic flows for the consented project were based on a series of parameters developed to inform the EIA (Table 2.1
refers).
7. To minimise the impact of the traffic generation, a transport strategy (set out in the ES and subsequent SEI) was developed
that would require vehicles associated with construction activities to access the onshore cable route using Primary and
Secondary Construction Consolidation Sites (CCSs). These sites would serve to control the movement of HGVs on the local
network to avoid specific time periods and be of an appropriate size and volume for the route that would be utilised.
8. To establish a realistic ‘worst case traffic scenario’ against which to assess the environmental impacts, the transport strategy
was applied to the parameters and augmented with a number of conservative assumptions (as set out in SEI Report Section
3.4, East Anglia Offshore Wind Limited 2013). The headline assumptions were:
• All Onshore Cable Route sections, HDD sections and Converter Station constructed concurrently.
• Haul road not used. Assessment assumes all movements between CCSs conducted via the existing road network. The
ES identifies the specific routes which would be used for HGV and personnel, and terms these the ‘Construction Access
Routes’.
• Estimates of vehicle movements per Onshore Cable Route section based on all construction activities for that section
happening at the same time e.g. arrival of trenching plant at same time as use of trenching plant, arrival of kit to
construct the haul road at the same time as use of the haul road.
9. These assumptions give an overestimate of the vehicle movements required at any one time. This ensures that the traffic
and transport assessment is based on the impacts of the maximum possible number of construction vehicles which would be
on the road network at any one time.
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10. Table 6.1 sets out the transport parameters and assumptions that form the basis of the traffic and transport assessment for
the consented project. It then identifies the proposed changes associated with the alternative project. Where a change is
identified, the table notes that the effects of this change must be further assessed.
Table 6.1 Transport parameters
Parameters Worst case definition (assumptions) Change for alternative
project
Further assessment
required?
Landfall
1. Temporary access track
1 track between public highway and
construction compound of 5.5m width.
No change No
2. Construction period
Up to 21 weeks.
Assumes 7 day week and 12 hour period
for traffic movements.
No change No
3. Construction HGV traffic
Maximum 38 HGV deliveries per day (2 x
PD250 rig site)
Potential for change No
There will be no
change to the HGV
demand assessed for
HDD mobilisation and
operation. There will
however be an
increase in the demand
for cabling and ducts at
HDD sites and this is
considered further
under parameter 11.
4. Construction workforce 9 personnel per day involved in HDD
operations at landfall.
No change No
5. Operation and
maintenance
One visit per year at jointing bays plus
non-scheduled maintenance if required.
No change No
Onshore cable route
6. Construction
Use of open-cut trenching along the
majority of the route assumed.
Assumes working width of 55m for
majority of onshore cable route.
Assumes working width of 160m at HDD
locations.
Assumes spoil removal off-site using
tipper trucks. Estimated 25 trucks per
week for removal of spoil. Assumes
importation of sand for backfill,
generating 20 trucks per week.
No change No
7. Cable number and
dimensions
Up to four onshore HVDC export cables
and fibre optics cables, plus eight ducts
for future projects.
Six trenches in total, for EA ONE two
trenches with two power cables installed
Potential for change Yes
Change to the number
of onshore cables from
four HVDC to six HVAC
has the potential to
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Parameters Worst case definition (assumptions) Change for alternative
project
Further assessment
required?
in each trench.
Cable route length: approximately 37km
change the maximum
HGV deliveries
forecast.
No change in
requirements for:
number of trenches;
cable route length;
sand bedding; and
spoil export.
8. HDD construction
compound
Compound area of 2500m2 at HDD rig
site; area of 2500m2 required at exit side.
No change No
9. Construction
Consolidation Sites
Assumes 7 CCSs (2 primary CCSs and
5 secondary CCSs. Primary site areas,
each of 15,000m2; secondary site areas
each of 10,000m2).
No change No
10. Construction period
Up to 44 weeks (46 converter station),
potentially spread over 2 years, 5 days a
week (see paragraph 17, Section 6.2.3
for further explanation); 12 hour days.
No change No
11. Construction HGV traffic
Maximum 29 HGV deliveries per day per
cable route section, of which seven were
associated with the delivery of cables
and ducts.
Potential for change
Yes
For each cable route
section additional
cables will be required
(as outlined under
parameter 7) and
additional ducts for
HDD crossings (as
outlined under
parameter 3)
The increase in cable
and ducting will result
in a requirement for
additional HGV
deliveries, potentially
causing an increase to
the peak daily figure of
29 HGV deliveries per
day to each cable route
section.
12. Construction workforce 79 personnel per 500km cable route
section per day.
No change No
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Parameters Worst case definition (assumptions) Change for alternative
project
Further assessment
required?
13. HGV deliveries Via two Primary Construction
Consolidation Sites (south-west of
Woodbridge and Clayton interchange)
and seven Secondary Construction
Consolidation Sites spread along the
route.
Delivery duration: 10 hours (no peak
hour movements between PCCS and
SCCS).
No change No
14. HGV routing A14 and A12 to PCCS.
From PCCS to SCCS to the
Development Area minimising the use of
the local highway network.
Where this is not possible due to ‘land
locks’ the Suffolk hierarchical HGV route
network will be utilised.
No change No
15. Operation and
maintenance
One visit per year plus non-scheduled
maintenance if required.
No change No
Converter station
16. Number and size of
onshore installations
One HVDC converter station
Maximum compound dimensions: 150m
x 190m
Maximum building dimensions:
130m x 85m x 25m
No change for the
proposed HVAC
substation
The maximum building
height will reduce from
25m to 21m
No
The maximum
compound and building
dimensions will not
increase and therefore
demand for HGVs to
import construction
materials will not
materially change.
17. Converter Station
Temporary Works Area
As shown in Volume 6, Figure 4.10 (East
Anglia Offshore Wind Limited, 2012)
No change for the
proposed HVAC
substation
No
18. Construction period
Up to 46 weeks.
14 HGV deliveries per day.
100 personnel per day.
No change for the
proposed HVAC
substation
No
19. Operation and
maintenance
Permanent staff of 5 plus additional
personnel for major maintenance work.
No change for the
proposed HVAC
substation
No
11. It can be noted from Table 6.1 that the only changes to the transport parameters associated with the alternative project are to
cabling and ducts; parameters 3, 7 and 11 refer. These changes are considered further in the subsequent updated
assessment.
6.2.3 Updated assessment
12. It is identified from Table 6.1 that the transport parameters that have the potential to increase the impacts described in the
existing assessment as a result of the alternative project changes are associated with cabling and duct.
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13. Plate 6.1 is taken from the SEI Traffic and Transport Chapter (East Anglia Offshore Wind Limited, 2013). It shows, for the
existing assessment, the construction traffic demand for each individual 5km section of the onshore cable route. This traffic
demand forms the basis of the existing traffic and transport assessment.
Plate 6.1 Detailed breakdown of HGV demand for each cable route section
14. As Plate 6.1 shows, the existing assessment was based on a peak HGV demand for each cable route section of 29 HGV
deliveries per day. As set out under methodology in this section, the only source of potential changes to the magnitude of
effects is the potential additional cable and duct HGV peak deliveries. Plate 6.1 shows that the existing assessment was
based on an assumption of seven HGV deliveries per section per day associated with cables and duct.
15. To assess if this peak cable and duct allowance could be accommodated by the alternative project, it is necessary to
compare the total cable and duct requirements for both options. Table 6.2 sets out the cable and duct requirements for the
consented and alternative projects.
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Table 6.2 Cable and duct pipe requirements for the consented and alternative projects
Parameters Consented project (up
to 1.2GW) +
associated
development
Alternative project
(up to 750MW) +
associated
development
Notes / assumptions
Length of cable section 5km 5km Seven cable sections
Number of lengths of duct associated
with HDD (EA ONE)
Four Six Consented project assumed four
lengths of duct pipe per HDD site;
alternative project assumes six
lengths of duct per HDD site.
Total number of cables Four Six Consented project assumed four
cables, alternative project assumes
six cables.
Total length of duct required for HDD
and trenchless crossing only (EA ONE))
18,880m 28,320m Estimated length of HDD and
trenchless crossing sections +
railway and road crossings and pinch
points (4,720m) multiplied by
number of cables
Estimated maximum length of duct for
an Onshore Cable Route Section (EA
ONE) **
8,000m 12,000m*** Estimated length of HDD and
trenchless crossing sections
(2,000m) multiplied by number of
cables
Maximum length of duct for future
projects*
40,000m 40,000m No change to consented project. For
each section there will be four
trenches for future projects each with
two ducts (eight ducts x 5000m)
Length of cable required * 20,000m 30,000m Length of cable section multiplied by
the number of cables
Number of HGVs to deliver ducts (EA
ONE + future projects)*
250 deliveries 271 deliveries A low payload of 192 linear metres
per HGV assumed reflecting the
need to use smaller vehicles to
access the cable route.
Number of HGVs required to deliver
cable *
40 deliveries 60 deliveries 500m of cable per HGV
Total number of HGVs to deliver duct
and cable*
290 deliveries
(580 two-way
movements)
331 deliveries
(640 two-way
movements)
A potential increase of 41 HGV
deliveries per cable route section
* per 5km section
** Onshore Cable Route Section 1, including landfall, Ferry Road and River Deben HDD sites.
*** It is noted that the alternative project proposes a reduction in offshore export cables from four to two. To provide flexibility
for future projects, six HDD sites and associated ducting have been assumed at the landfall.
16. From the data outlined above, the following information has been derived:
• The alternative project would be associated with an increase in cable and duct deliveries;
• The consented project assessed seven HGV deliveries per day for cabling and ducting; and
• The total deliveries that would be required for the alternative project cabling and duct (including future project ducts)
would be 331, a potential increase of 41 HGV deliveries per section to the consented project.
17. Table 6.1 notes that the construction duration for each 5km cable section is 44 weeks. Allowing for section mobilisation and
de-mobilisation, the period for cable laying and installing ducts is conservatively estimated at 32 weeks or 160 potential
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delivery days (five days per week). Furthermore, whilst five days per week was used to test a worst case, the consented
project allows for Saturday working, which could potentially increase the number of delivery days further.
18. Taking the seven deliveries per day maximum as a constraint for the rate of deliveries, all cable and ducts required for the
alternative project could theoretically be delivered to site in a minimum time period of 48 days (331 total HGV deliveries ÷
seven per day). This minimum delivery time period is significantly less than the 160 delivery days assessed and reveals up
to 112 days of contingency. It can therefore be concluded that the cable and ducts for the alternative project can comfortably
be delivered within the existing assessment peak of seven deliveries per day.
19. In real terms, the process of laying cable is a linear activity which lends itself to an even profile of deliveries, save for limited
peaks in demand (e.g. during mobilisation when it might be beneficial for some stockpiling in advance). Therefore, the total
331 deliveries of cable and ducts are likely to be spread across the entire 160 day delivery window.
20. Peak cable and duct deliveries for stockpiling would be carefully planned to avoid ‘critical path’ items to ensure that the
overall existing assessment, of a maximum of 29 HGV deliveries per day per cable route section, would not be exceeded.
For example, concrete for joint pits and backfill sand would not be required when mobilising. Concrete and backfill sand is
assessed as a peak of six HGV deliveries per day within the maximum 29 HGV deliveries per day (Plate 6.1 refers), this
allocation and programme window could be utilised for the import of cable and ducts when mobilising a cable route section.
21. It is therefore concluded that the forecasts of the peak construction traffic flows utilised in the existing assessment will not be
changed by the alternative project and therefore the conclusions as set out in the existing assessment for the consented
project are unchanged for the construction phase.
22. Table 6.1 notes that the alternative project does not represent a change to operation and maintenance traffic, and therefore
the existing assessment for the operational phase is also unchanged.
23. With respect to air quality and noise, which were screened in (Section 5) in relation to HGV traffic, since the updated traffic
and transport assessment confirms that the worst case traffic flows are unchanged, there will also be no change in impact
significance for either of these topics.
6.2.4 Conclusions
24. It has been demonstrated that an alternative option to construct and operate an up to 750MW windfarm with HVAC
transmission infrastructure would not change the worst case traffic flows that informed the assessment of the consented
project. It is therefore concluded that the potential impacts associated with the proposed changes are no greater than those
previously presented for the consented project. As such, no changes are proposed to the requirements in the DCO regarding
mitigation for traffic and transport impacts, namely Requirement 25 regarding implementation of a Traffic Management Plan,
a Travel Plan and an Access Management Plan upon commencement of the works.
25. These documents will set out the standards and procedures for managing the impact of the proposed project’s traffic. Prior
to commencement of construction, they will be finalised and agreed with relevant highway stakeholders in order to manage
the number, timing and types of vehicles generated on the highway network having regard to the assessed transport
parameters and the identified sensitive routes/junctions.
6.3 Landscape and Visual Impact
6.3.1 Introduction
26. Table 2.1 sets out the parameters of the consented 1.2GW HVDC project and the changes that would be required under the
proposals for the alternative project of up to 750MW. The following parameters are of particular relevance to landscape and
visual impact assessment (LVIA):
Onshore Cable Route
• Number and size of onshore installations;
• Construction period and traffic; and
• Working width.
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Converter Station Compound
• Number and size of onshore installations;
• Equipment height dimensions;
• Construction period and traffic; and
• Operational lighting.
6.3.2 Methodology
27. In order to assess if the magnitude of effect would be reduced, the LVIA chapter of the ES was reviewed. The basis of the
judgements and conclusions and the previously listed parameters were reviewed. This was carried out for the onshore cable
route and the onshore HVDC converter station compound (the latter being termed an onshore HVAC substation under the
alternative project).
28. In order to assist the review of the changes at the converter station compound, the original photomontages were reproduced
in order to explore the visual effects of the alternative option on a number of selected viewpoints. The key proposed changes
to project description parameters in relation to the onshore converter station/substation are summarised in Table 6.3 below.
Table 6.3 Key proposed changes to the onshore converter station/substation parameters
Parameter Consented up to 1.2GW HVDC
project
Alternative up to 750MW HVAC project
Number and size of onshore
installations
One HVDC converter station
Maximum compound dimensions:
150m x 190m
Maximum building dimensions:
130m x 85m x 25m
One HVAC substation
Maximum compound dimensions: No change
The maximum building dimensions are
dependent on the balance of indoor and outdoor
equipment but will be no greater than the
dimensions used in the original assessment
Equipment height dimensions Primarily indoor but substantial
amount of outdoor electrical
equipment
Maximum height of building: 25m
Maximum height of outdoor electrical
infrastructure: 10m (excluding
compound perimeter lightning
protection and support gantries: 25m)
Range: 70-90% outdoor, 10-30% indoor
Maximum height of building: 18m if mostly
outdoor equipment, 21m if mostly indoor
equipment
Maximum height of outdoor electrical
infrastructure: 15m (excluding compound
perimeter lightning protection and support
gantries:18m)
29. The new photomontages illustrate two scenarios which represent the potential variation in outdoor and indoor equipment
associated with the proposed substation.
30. Two scenarios have been produced and analysed in order to investigate a range of electrical equipment and buildings which
might be included within the substation compound. The scenarios include a number of worst case options such as electrical
equipment enclosed in buildings which result in taller structures than the same situation with just the electrical equipment. In
addition the two scenarios include a range of building heights with a variation in their locations within the compound and also
include the taller outdoor electrical infrastructure. Please refer to Figures 1 and 2 (Appendix 1) which illustrate the two
scenarios graphically and identify the locations of the various components within the substation compound.
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31. The final design of the onshore HVAC substation will be delivered through discharge of Requirement 10 of the DCO
(‘Detailed Design Approval Onshore’) and accord with the Outline Converter Station Design Principles, which will still be
relevant to the substation.
32. The new photomontages illustrate the proposed substation from the same viewpoints as those in the ES which were:
• Viewpoint 3 – Public Right of Way (PRoW) near Flowton;
• Viewpoint 5 – Orchard Lands near Canes Farm (Residential and PRoW);
• Viewpoint 10 – PRoW near Fidgeon’s Farm; and
• Viewpoint 15 – Church Hill, Burstall (Lane and local high point).
33. All of the viewpoint locations as assessed in the ES are shown on Figure 3, Appendix 1.
34. For each viewpoint, the new photomontage includes an existing view, a year 1 view and a year 15 view for each scenario.
This includes both winter and summer views except for viewpoint 15 which is summer only as per the original ES, which was
agreed with the Local Planning Authorities. These new photomontages include the mitigation planting as did the original
photomontages. Please refer to Figures 4 to 10 (Appendix 1).
35. Notwithstanding the focus on these particular viewpoints, the other viewpoints included in the ES were also reviewed and a
judgement made on any changes to the assessment.
6.3.3 Summary of the original assessment
Construction
36. With regard to construction impacts arising from the cable route, the LVIA concluded that there would be the following levels
of significant effect on landscape receptors:
• Landscape Designations – Major;
• Field Boundaries – Not significant;
• Grassland – Moderate; and
• Trees and Woodland – Major.
37. In terms of visual effects arising from the construction of the cable route, the LVIA concluded that these would be mainly
major. A much smaller number of moderate effects were also reported. The majority of these significant visual effects would
arise from the removal of existing trees and hedgerows and the changes this would have on existing views.
38. In the case of the converter station compound, it was reported that moderate significant landscape effects would arise during
the construction period. The temporary visual effects during the construction period would be major significant.
Operation
39. The LVIA concluded that there would be no operational effects arising from the onshore cable route, as the cables and
jointing bays would be buried. It was noted that above ground kiosks would be necessary for the jointing bays. In addition,
permanent marker posts would be visible along the route. However, the presence of these new elements was not considered
significant in terms of landscape and visual impact.
40. In terms of the converter station compound, the assessment concluded that with reference to landscape, there would be a
moderate significant operational effect. This took into account the proximity of the existing substation, the partial loss of key
elements and the introduction of noticeable elements including outdoor equipment, albeit not substantially uncharacteristic
when set within the landscape.
41. With reference to operational visual impacts arising from the converter station compound, the assessment concluded that
there would be major significant effects on sensitive receptors at the following viewpoints:
• Viewpoint 2 – Flowton Village;
• Viewpoint 5 - Orchard Lands near Canes Farm (Residential and PRoW);
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• Viewpoint 6 – Near Hill Farm;
• Viewpoint 7 – Burstall;
• Viewpoint 10 – Near Fidgeon’s Farm;
• Viewpoint 11 – Near Bullenhall Farm; and
• Viewpoint 12 – Near Tye House.
42. Moderate significant effects would be experienced at the following viewpoints:
• Viewpoint 3 – Flowton Village;
• Viewpoint 9 – Thornbush Hall; and
• Viewpoint 15 – Church Hill, Burstall.
43. The other five viewpoints were considered to experience not significant effects during operation.
6.3.4 Updated assessment
Construction impacts
44. It is clear from a review of Table 2.1, that the construction and installation of the onshore cable route would be similar with
regard to relevant operations, equipment and timeframes. Examples include the construction period, the working width
generally and its reduction at HDD locations and pinch points. In addition, the cable depth is the same. It is considered
therefore that the landscape and visual impacts would not be worse than those originally reported.
45. With regard to the new substation, the period of construction, the overall location and the size of compound are all the same
as that originally assessed for the converter station compound. It is considered therefore that the landscape and visual
impacts would not be worse than those originally reported.
Operation impacts
46. In terms of the onshore cable, there is no change to the worst case associated with the alternative project in respect that the
cables and jointing bays would be buried and the same marker posts and kiosks would appear above ground. It is
considered therefore that the impacts would not be worse than those originally reported.
47. The new photomontages illustrating the proposed substation have been used to assist the assessment of the proposals on
landscape and visual resources. These have been compared against the photomontages illustrating the converter station
compound.
48. Reference to the figures illustrating the layout of the two scenarios, Figures 1 and 2 (Appendix 1) illustrate that the buildings
and equipment for the proposed substation have a less cohesive layout than that included for the converter station
compound. For the latter, the two large converter station buildings were located side by side towards one side of the overall
compound, with the outdoor electrical equipment filling the remaining space. In both scenarios for the substation, the
electrical equipment and the various buildings are placed according to their function and electrical requirements. As a result,
the larger buildings are located in several places within the overall compound.
49. The following table (Table 6.4) presents an analysis of the new photomontages for each scenario of the proposed substation
and compares them against the original photomontages for the converter station compound.
50. The analysis illustrates that the potential magnitude of effects associated with the proposed changes are no greater than
those previously assessed for the consented project, with no resulting change in significance.
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Table 6.4 Analysis of viewpoint photomontages
Viewpoint Original photomontage
Converter Station Compound
New photomontage
Scenario 1 (equipment external/outdoors)
New photomontage
Scenario 2 (equipment internal/indoors)
Viewpoint 3 - PRoW near Flowton Winter
At the start of operations (year 1), the
higher parts of the building walls,
including the roofs, are visible above
the existing woodland. This
woodland screens the remaining
parts of the building and other
electrical equipment.
At year 15 there is very little change
as the mitigation planting does not
provide any further screening from
this viewpoint.
Summer
Although more dense, the summer
vegetation does not provide
additional screening of the higher
parts of the buildings. This is the
same for both years 1 and 15.
Winter
At the start of operations (year 1), the higher
parts of one of the buildings is barely visible
above the existing woodland. Other electrical
equipment is screened by the existing woodland.
At year 15 there is very little change as the
mitigation planting does not provide any further
screening from this viewpoint.
Summer
Although more dense, the summer vegetation
does not provide additional screening of the
higher parts of the buildings. This is the same for
both years 1 and 15.
Winter
At the start of operations (year 1), the higher
parts of a number of the buildings are visible
above the existing woodland. Other electrical
equipment is screened by the existing woodland.
At year 15 there is very little change as the
mitigation planting does not provide any further
screening from this viewpoint.
Summer
Although more dense, the summer vegetation
does not provide additional screening of the
higher parts of the buildings. This is the same for
both years 1 and 15.
Viewpoint 5 – Orchard Lands near
Canes Farm (Residential and
PRoW);
Winter
At the start of operations (year 1), the
higher parts of the building walls,
including the roofs, are visible above
the existing hedgerows. The
hedgerows screen the remaining
parts of the building and the works
within the compound.
At year 15, the mitigation planting
provides a fair degree of screening
with less of the gables of the
buildings and roofs visible.
Summer
The summer vegetation provides a
Winter
At the start of operations (year 1), the higher
parts of the walls of one of the buildings,
including the roofs is visible above the existing
hedgerows. In addition the Stacom electrical
components and a number of other components
are partially visible above the existing hedgerow.
At year 15, the mitigation planting provides a fair
degree of screening with less of the building
gable visible. The Stacom electrical components
are also more effectively screened.
Summer
The summer vegetation provides a good degree
of screening of the gables to the buildings with
Winter
At the start of operations (year 1), the higher
parts of a number of the buildings are visible
above the existing hedgerow. Parts of the
electrical equipment are also visible.
At year 15, the mitigation planting provides a fair
degree of screening with less of the building
gables visible. The electrical components are
also more effectively screened.
Summer
The summer vegetation provides a good degree
of screening of the gables to the buildings with
only the uppermost parts of the building visible by
year 15 and the top parts of the electrical
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Viewpoint Original photomontage
Converter Station Compound
New photomontage
Scenario 1 (equipment external/outdoors)
New photomontage
Scenario 2 (equipment internal/indoors)
good degree of screening of the
gables to the buildings with only the
roofs visible by year 15.
only the uppermost parts of the building visible by
year 15 and the top parts of the electrical
components.
components.
Viewpoint 10- PRoW near
Fidgeons Farm
Winter
At the start of operations (year 1), the
higher parts of the building walls,
including the roofs, are clearly visible
above the existing hedgerows.
At year 15, the mitigation planting
provides some screening to
approximately 50% of the exposed
gables with the roofs still visible.
Summer
The summer vegetation provides a
further degree of screening to those
areas already screened during
winter. This applies more so in year
15 where the summer mitigation
planting appears more effective.
Winter
At the start of operations (year 1), the electrical
components are barely visible above the existing
hedgerows and between the existing trees with
the buildings barely visible.
At year 15, the mitigation planting provides some
additional screening.
Summer
The summer vegetation provides a further
degree of screening to those areas already
screened during winter.
Winter
At the start of operations (year 1), the higher
parts of a number of the buildings are visible
above the existing hedgerows and between the
existing trees.
At year 15, the mitigation planting provides some
additional screening but parts of the upper gables
and roofs are still visible.
Summer
The summer vegetation provides a further
degree of screening to those areas already
screened during winter.
Viewpoint 15 – Church Hill,
Burstall (Lane and local high
point)
Summer
The Converter Station Compound
cannot be seen from this viewpoint
and therefore is represented as a red
outline on the photomontage.
Summer
The Converter Station Compound cannot be
seen from this viewpoint and therefore is
represented as a red outline on the
photomontage.
Summer
The Converter Station Compound cannot be
seen from this viewpoint and therefore is
represented as a red outline on the
photomontage.
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Decommissioning impacts
51. It is considered that the decommissioning impacts for Landscape and Visual would be no worse than those originally reported
in the existing assessment due to the decrease in the size and mass of the substation buildings compared to those for the
converter station and the fact that both operational compounds would be the same size.
Cumulative impacts
52. It is considered that the cumulative impacts for Landscape and Visual would be no worse than those originally reported in the
existing assessment due mainly to the decrease in the size and mass of the substation buildings compared to those for the
converter station.
Mitigation measures and residual impacts
53. The mitigation measures are the same as those proposed for the existing assessment and the residual impacts would be no
worse than those originally reported.
6.3.5 Conclusions
54. With regard to the alternative project and the changes to the onshore cable route, it is concluded that the potential magnitude
of effects associated with the proposed changes are no greater than those previously assessed for the consented project,
with no resulting change in significance.
55. With regard to the alternative project and the changes to the substation compound, an analysis of the two scenarios
illustrates that the various options and ratios of building to equipment do not make a material difference. The potential
magnitude of effects associated with the proposed changes are no greater than those previously assessed for the consented
project, with no resulting change in significance.
56. As a consequence, no changes are proposed to the requirements in the DCO regarding mitigation for landscape and visual
impacts, namely requirements 10 and 12.
7 Conclusions 1. EAOL is seeking to vary the existing DCO for the East Anglia ONE offshore windfarm to include an alternative option to
construct an up to 750MW windfarm utilising HVAC transmission infrastructure.
2. This report has considered the potential impacts of the alternative (up to 750MW) project and compared them to the
conclusions reached in the existing assessment for the consented (up to 1.2GW) project.
3. Following the outcome of an environmental screening exercise and updated assessment with respect to traffic and transport
and landscape and visual effects, it demonstrates that the potential magnitude of effects associated with the proposed
changes are no greater (and would in many cases be less) than those previously assessed for the consented project, with no
resulting change in significance.
4. It is therefore considered that the proposed changes would constitute non-material amendments for the purposes of the
Infrastructure Planning (Changes to, and Revocation of, Development Consent Orders) Regulations 2011 (as amended).
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8 References East Anglia Offshore Wind Limited (2012). East Anglia ONE Offshore Windfarm – Environmental Statement.
East Anglia Offshore Wind Limited (2013) East Anglia ONE Offshore Windfarm – Post-Submission Report 1 and
Supplementary Environmental Information.
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Appendices
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Appendix 1 Landscape and Visual Impact Assessment figures
Please see Folder 2 of application materials