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NAVITUS BAY WIND PARK Response to Deadline VII
Appendix 14 Updated Outline Diver Management Plan
5 March 2015
Application Reference: EN10024
Navitus Bay Development Limited
navitusbaywindpark.co.uk
Navitus Bay Wind Park
Response to Deadline VII
Appendix 14
Outline Diver Management Plan
Navitus Bay Wind Park
Response to Deadline VII
Page ii Appendix 14
Outline Diver Management Plan
DOCUMENT CONTROL
DOCUMENT PROPERTIES
Organisation
Author Navitus Bay Development Limited
Checked by DM
Approved by SG
Title Outline Diver Management Plan
Document
Reference
8.7
VERSION HISTORY
Date Version Status Description/Changes
10 April 2014 1.0 Final Issued for application
submission
28th January 2015 1.1 Final Inclusion of Appendix
A
5th March 2015 1.2 Final MMO requested amendments
Any persons intending to use this document should satisfy themselves as to its applicability for
their intended purpose.
In preparation of this document Navitus Bay Development Limited and their subcontractors
have made reasonable efforts to ensure that the content is accurate, up to date and complete
for the purpose for which it was prepared.
Neither Navitus Bay Development Limited or their subcontractors make any warranty as to the
accuracy or completeness of material supplied.
Neither Navitus Bay Development Limited or their subcontractors shall have any liability for
any loss, damage, injury, claim, expense, cost or other consequence arising as a result of use
or reliance upon any information contained in or omitted from this document.
© Copyright Navitus Bay Development Limited 2014
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TABLE OF CONTENTS
1. Executive Summary ....................................................................... 1
2. Introduction .................................................................................. 2
2.1 Diving Overview............................................................................. 2
3. Project Description ......................................................................... 3
3.1 Project Overview ............................................................................ 3
4. Consultation .................................................................................. 6
4.1 Consultation summary .................................................................... 6
5. Potential Diving Impacts ................................................................. 7
5.1 Introduction .................................................................................. 7
6. Mitigation Plan ............................................................................... 9
6.1 Proposed mitigation measures ......................................................... 9
7. Communication strategy ............................................................... 13
7.1 Introduction ................................................................................ 13
8. Summary .................................................................................... 16
8.1 Introduction ................................................................................ 16
9. Appendix A: List of Consultees ....................................................... 17
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LIST OF TABLES
Table 4.1 – Consultation to date ................................................................ 6
Table 4.1 – Proposed mitigation measures .................................................. 9
LIST OF FIGURES
Figure 3.1 - Indicative foundation design options, excluding suction caisson. .. 4
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1. Executive Summary
1.1.1 This Outline Diver Management Plan sets out the key principles of
how Navitus Bay Development Limited (NBDL) intends to manage
and minimise the risk posed by offshore activities to the diving
community in the proximity of the Navitus Bay Wind Park (the
Project).
1.1.2 It contains a number of proposed management and mitigation
measures which will be implemented during the offshore construction
phase. These will include a patrolled minimum 2 km temporary
avoidance zone around each pile driving activity; the implementation
of a communication strategy with the local diving community and the
appointment of a Diving Liaison Officer (DLO).
1.1.3 The communication strategy will be developed with the diving
community to ensure they are kept informed of the proposed offshore
construction activities. The DLO will act as a focal point between
NBDL/ its contractors and the diving community. The DLO will work
with the community to ensure the safety of the diving community is
maintained during the construction period.
1.1.4 This Outline Diver Management Plan will inform the preparation of a
detailed Diver Mitigation Plan, to be finalised prior to commencement
of construction and approved by the Marine Management
Organisation (MMO). The appropriateness of the final required
mitigation for diving activities will be consulted upon prior to MMO
sign off with industry representatives and local stakeholders (for
details see Appendix A). The final approved plan will be implemented
throughout the construction of the Project. Input into the Outline
Diver Management Plan has been achieved through ongoing
consultation with the diving community itself, from appointed
experts, the British Sub-Aqua Club and from review of guidance notes
produced by the Health & Safety Executive, to ensure that the Project
will not pose any risk to divers in the vicinity of the construction
works.
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2. Introduction
2.1 Diving Overview
2.1.1 The purpose of this Outline Diver Management Plan is to provide the
diving community with a clear proposal on how NBDL intends to
manage recreational scuba diving during the construction phase of
the Project. The potential impacts to diving during the life time of the
Project are addressed in Volume D Chapter 4 of the Environmental
Statement (Document 6.1). This plan gives further detail on the
proposed mitigation measures that will be employed during
construction.
2.1.2 Diving is a popular activity in the region and 143 dive sites have been
identified between Lyme Regis and the east of the Isle of Wight,
including 13 within the Offshore Development Area. Sites are either
accessed directly from shore or by boat.
2.1.3 The main areas for diving vary from specific locations such as
Kimmeridge Bay, Poole Harbour and Swanage Bay to the entire
coastal strip running from the Isle of Wight along to Weymouth.
Popular dive sites include the wrecks of the Kyarra, the Betsy Anna
and the Venezuela. Most of the dive clubs and charter boats indicated
that they use sites within or near the Offshore Development Area,
including but not limited to: the wrecks of SS Eleanor, SS Hazelwood,
and Christchurch Ledge.
2.1.4 Popular embarkation locations are Poole (Harbour and Harbourside
Park), Swanage and Kimmeridge Bay. The reasons for embarking
from these points were ease of access to dive sites and
convenience/locality for members. Weymouth and Lymington are also
important embarkation areas for divers. This information has been
obtained through consultation with the local diving community.
2.1.5 The Turbine Area is one of the locations used for deep water diving.
This type of diving often involves decompression stops during ascent,
during which the diver may drift over a substantial distance.
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3. Project Description
3.1 Project Overview
3.1.1 NBDL is seeking development consent for the Project, which in
summary comprises the following:
up to 194 wind turbines and towers;
up to 198 foundations and associated scour protection (where
necessary);
up to three Offshore Substation Platforms;
up to one meteorological mast;
offshore cabling comprising inter-array cables, inter- substation
cables and export cables;
the Landfall which is located at Taddiford Gap, between Barton-on-
Sea and Milford-on-Sea on the Hampshire Coast;
a 35 km Onshore Cable Corridor, which would be entirely
underground and is required to transmit the electricity generated
by the offshore wind park to an onshore grid connection point; and
a new Onshore Substation located in Three Legged Cross, a village
north of Ferndown in Dorset, which is required to transform the
electricity voltage up to 400 kV appropriate for the UK
transmission system network.
3.1.2 The Project is located on the south coast of England, offshore from
Dorset and Hampshire. At the nearest points to land the wind
turbines would be: approximately 14.4 km (8.9 miles) from Durlston
Head (on the Isle of Purbeck) and 17.3 km (10.7 miles) from
Scratchell’s Bay (just south of the Needles on the Isle of Wight).
3.1.3 The process of project development, from consent to construction,
can take a number of years, the offshore wind industry is still
developing, and the size of projects expanding. To ensure a project
that is assessed prior to consent remains technically and economically
viable at the point of construction, a variety of influences and
uncertainties have to be addressed. For example turbine technology
is developing and there may be uncertainty at the consent application
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stage about the availability and cost of different turbines by the time
of construction, and in turn turbine type would influence the most
effective and appropriate choice of foundation. Therefore NDBL is
considering a range of foundations as part of its design envelope for
the Project.
3.1.4 Each foundation type has different installation requirements and
techniques. Each installation technique creates different levels of
noise and therefore has a varying impact on diving activities.
3.1.5 The following turbine foundation options are under consideration for
the Project:
Gravity Base Structure (GBS);
Steel monopile foundations;
Space frame structures (steel jacket, tripile or tripod);
Suction caisson options (either a monopile or jacket with suction
caissons).
3.1.6 Figure 3.1 shows indicative foundation design options, excluding
suction caisson.
Figure 3.1 - Indicative foundation design options, excluding suction
caisson.
3.1.7 Monopile foundations create the highest level of noise during
installation and are therefore considered to have the greatest impact
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on diving activities. If monopile foundations are not used, noise levels
would be reduced and the impact level on diving would be lessened.
Therefore mitigation measures proposed for diving have been based
on the noise levels associated with the installation of monopile
foundations, which represent the worst case scenario.
3.1.8 The decision on foundation(s) design would be taken prior to the
point of installation, following the completion and analysis of site-
specific geotechnical investigations. The final foundation decision will
be based on a range of factors, including water depth tidal, wind and
wave conditions; logistical practicalities; commercial factors; ease of
construction and installation; and the type and size of turbine chosen.
3.1.9 For a more detailed description of the offshore Project elements refer
to Volume B Chapter 2 Offshore Project Description of the ES
(Document 6.1).
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4. Consultation
4.1 Consultation summary
4.1.1 NBDL has engaged with the diving community throughout the
development of the Project. Outside of the four phases of public
exhibitions and consultation, NBDL has carried out a number of
consultation activities which are detailed in Table 4.1 below.
Table 4.1 – Consultation to date
Consultee Method Topic discussed
Dive businesses Face to face meetings
Between 2012 and 2014
The project and potential impacts
Impacts to business
operations
Mitigation measures
DIVE 2013,
National Dive conference
(Birmingham NEC)
Stand at the conference
with project hand-outs
November 2013
The project and potential
impacts
Experiences of diving
close to offshore construction sites
Diving clubs and
business
Diving workshop held in
Bournemouth.
November 2013
The project and potential
impacts
Popular dive sites
Proposed mitigation
measures
Benefits to the diving community
British Sub- Aqua Club Meeting and presentation
January 2014
The project and potential
impacts
Proposed mitigation
measures
Benefits to the wider
diving community
Education and research opportunities
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5. Potential Diving Impacts
5.1 Introduction
5.1.1 The section below sets out at a high level the two potential impacts
which the offshore construction activities could have on diving in the
waters surrounding the Offshore Development Area. The Offshore
Development Area comprises the Turbine Area and the Offshore
Export Cable Corridor shown in Figure 6.1 below. The two impacts
identified are:
noise levels from the installation of monopile foundations;
reduction in visibility due to disturbance of seabed sediment from
the installation of foundations and offshore cabling.
a) Noise
5.1.2 The English Channel between the Isle of Wight and Swanage is a
popular site for divers. During installation of foundation piles at the
Turbine Area, the noise generated by impact piling has the potential
to cause an aversive reaction to divers underwater, particularly at the
commencement of piling as detailed below.
5.1.3 The effect of the noise generated by the piling would vary depending
on how close a diver is to the noise source, and would vary between
physical harm and a short-term effect on the diver’s hearing. A noise
threshold of 130 dB(UW), slightly more conservative than the level
noted in the Control of Noise at Work Regulations 2005, is suggested
for the onset of hearing damage. The range for 130 dB (UW) is
predicted to be up to 185 m from a piled foundation site.
5.1.4 Divers are also potentially at risk of indirect effects as a consequence
of exposure to high noise levels. A sudden high noise exposure could
potentially startle an inexperienced diver and cause him to surface
too quickly in panic. This could lead to an increased risk of
decompression sickness. There are no existing guidelines as to
acceptable levels of noise in respect of startle response. However, a
level of 110 dB(A) in air is judged to be “very loud” and it is therefore
considered to form a suitable criterion. It is therefore recommended
that until better information is available, a level of 110 dB (UW) peak
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level is adopted as a criterion for a level of noise above which strong
aversive reaction may occur.
5.1.5 A potential startle reaction is estimated at around 4 km from the pile
site. Provided that divers are aware that underwater piling noise
could occur during their dives, any risk of a startle reaction would be
minimised.
5.1.6 As a consequence, it is acknowledged that during construction there
would be a significant impact to divers due to the reduction in access
to dive sites in the Turbine Area and the vicinity of the Offshore
Development Area.
5.1.7 Section 6 details the mitigation measures proposed to minimise the
impact on divers during offshore construction activities.
b) Visibility
5.1.8 The methods considered for both foundation installation and offshore
cable laying have been designed to minimise and control the release
of silt into the surrounding water column. The volume of sediment
released will depend on the sediment type at that particular location.
Across the majority of the Turbine Area, the sediment is coarse
gravel, which would not create persistent sediment plumes, but would
fall directly to the seabed.
5.1.9 Volume B Chapter 5, Physical Processes of the ES (Document 6.1)
details the potential impacts of increased sediment suspension in the
water column. This can have the effect of reducing diving visibility.
No significant effects have been identified in this chapter in relation to
the increase of suspended sediment in the water column. Therefore
no mitigation measures are proposed in relation to impacts to
visibility.
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6. Mitigation Plan
6.1 Proposed mitigation measures
6.1.1 Health and Safety protocol is the main priority for the Project and
NBDL will endeavour to eliminate, where possible, the risks caused
from the offshore construction of the proposed wind park. Where it is
not possible to eliminate the risk, mitigation measures have been
proposed to reduce the risks as far as practicable to ensure the safety
of divers in the region.
6.1.2 Figure 6.1 shows the Offshore Development Area, known wreck sites
and an indicative 2 km “diving avoidance area.” Table 6.1 below sets
out the proposed mitigation measures, its purpose and how it will be
implemented.
Table 6.1 – Proposed mitigation measures
Mitigation Measure Purpose Implementation Process
Appointment of a Diving Liaison
Officer (DLO)
To act as a focal point of contact for
all diving concerns
NBDL has already appointed a DLO to support engagement and
consultation during the pre-
application stage. The DLO has
spent time meeting diving groups and businesses. If a DCO is
granted the DLO will continue their
role and will lead the engagement
process and will be in post until construction is completed.
Communication Plan
To provide up to date construction
information to all
diving related contacts of offshore
construction works
All interested parties will be identified and details stored on one
database. This will be monitored
and updated as required. Information will be shared with all
interested parties at regular
intervals via email, newsletter,
specialist diving media and social media as well as placing notices at
relevant coastal locations, Notices
to Mariners and coastguard
notifications.
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Table 6.1 – Proposed mitigation measures
Mitigation Measure Purpose Implementation Process
A minimum 2 km diver avoidance
zone around each
foundation during
construction of a
piled foundation
To ensure no diver strays into areas
where noise levels
are above the noise
threshold. To inform
divers of where it is safe to dive and
when.
Guard vessels will be employed to manage the 2 km buffer round
each pile site. Patrols will
commence at least half an hour
prior to works commencing in
order to warn any divers in the vicinity at that time.
However, divers will be recommended to give 4 km
clearance from each pile as this
will be outside the threshold that
could cause a startle reaction (as opposed to potential physical
harm) if a diver was unaware of
the construction activity.
Soft start procedure
for pile driving.
This is a procedure
whereby the hammer blow force
and therefore the
sound levels
produced is started at a low level (20%
of maximum
hammer energy),
ramping up in a stepwise manner to
the full force (1800
kJ for monopile and
1400 kJ for space
frame foundations).
To reduce the risk of
shock noises and allow divers who
may be in the water
to adjust to the type
of noise or make their way out of the
water.
The hammers employed to pile the
foundations will increase the energy used over a minimum 20
minute period. It is also expected
to be unlikely that full hammer
blow energy levels will be required for most foundations; therefore
reducing the peak noise level in
the water column. The 2 km
avoidance zone will still be maintained as a precautionary
measure even if hammer blow
energies are reduced.
Noise reduction technology
To reduce the noise at source of the
construction activity.
Specific technology is being developed to help dampen or
reduce the noise emitted from
piled installations.
These techniques are currently in
development the appropriateness
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Table 6.1 – Proposed mitigation measures
Mitigation Measure Purpose Implementation Process
of each method will be assessed
prior to construction and utilised if
deemed suitable.
6.1.3 Detailed surveys of the Offshore Development Area have been
undertaken to identify the locations of known wrecks. Turbines will be
located a minimum of 50 m from these known locations to ensure the
construction works do not affect them.
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Figure 6.1 – Diving Locations
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7. Communication strategy
7.1 Introduction
7.1.1 The fundamental principle of the diving communications strategy is
early consultation with the diving community in order to build an
effective working relationship. The engagement process described in
this section is intended to identify all the issues perceived by diving
stakeholders, both positive and negative.
7.1.2 The proposed communication plan (to sit within the Diver
Management Plan) comprises the following elements:
appointment of a DLO;
pre-construction information programme;
face to face engagement; and
construction phase updates.
a) Appointment of a Diving Liaison Officer (DLO)
7.1.3 NBDL has appointed a Diving Liaison Officer (DLO) who has extensive
experience working in the diving community in the region and has
assisted in compiling a comprehensive database of diving related
contacts from Portland to the Isle of Wight.
7.1.4 The role of the DLO going forward will be to ensure the contact
database is kept updated, to advise NBDL on diving related matters
and to act as a single focal point with relevant expertise to engage
with the broad range of groups and individuals who practice or have
interests in diving within the region.
7.1.5 It is proposed that the need for a DLO will continue until completion
of the offshore construction of the Project.
b) Pre-Construction Information programme
7.1.6 A newsletter for the diving community will be prepared for circulation
to those on the diving community database at least three months in
advance of offshore construction commencing, to include the
following content:
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overview of the Project;
an explanation of the piling noise and the potential impacts on
divers;
information on the construction process, including Project
elements and expected programme;
detailed health and safety information relating to the purpose and
locations of the avoidance zones and construction procedures;
map of the Offshore Development Area and turbine locations
(including coordinates), wreck sites of interest to divers and safe
distance recommendations; and
contact details for the DLO and the Project website and telephone
hotline number.
7.1.7 Copies of the newsletter will also be placed in dive shops and tourism
information offices to ensure divers who are not affiliated to a local
club are aware of the construction process and programme.
7.1.8 Articles, press releases and advertisements will also be published at
appropriate times during the pre-construction period to seek to
maximise awareness of the upcoming works.
c) Face to Face Engagement
7.1.9 It is proposed that there will be opportunities for the diving
community to meet formally with the Project team and the DLO at
regular intervals. These will take the form of presentations and
workshops where the diving community will be invited to raise issues,
gather information and understand more about the Project as it
progresses through construction. The locations of the events will be
spaced around the bay so there is opportunity for all to attend. It is
proposed these meetings will commence pre-construction and
continue during construction.
7.1.10 The DLO will of course be available during construction to meet
informally with any diving business or club to discuss the construction
of the Project and receive feedback on the communication strategy.
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7.1.11 To date NBDL has engaged with the local diving community and
businesses, exhibited at the National Dive Conference (DIVE 2013 at
the Birmingham NEC) and liaised with BSAC and PADI.
d) Construction Phase Updates
7.1.12 NBDL and the DLO will communicate information prior to
commencement of piling works, and ongoing through the construction
phase, to the diving community via:
Notices to Mariners issued at key stages during construction –
these will be sent to relevant maritime agencies and posted to the
Project website;
coastguard notifications via radio, advising all diving charter boats
to confirm dives with the Coastguard prior to commencing;
email alerts and notifications to the local diving community and
associated partners, detailed on the contact database;
specialist diving media channels such as blogs, publications and
articles diving newsletters;
a telephone hotline, with daily pre-recorded message updates
regarding the construction, which can take account of changes in
the weather;
a dedicated page available on the Project website;
hyperlinks from diver websites, forums and social media to the
Project website, articles and press releases;
signs posted at popular beaches, slipways, launch points, diving
shops, air recharge points, marinas and diving clubs;
social media sites, such as Facebook and Twitter.
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8. Summary
8.1 Introduction
8.1.1 This Outline Diver Management Plan provides the basis for the Diver
Management Plan which will be finalised prior to commencement of
construction and the appropriateness of the final required mitigation
will be consulted upon prior to MMO sign off with industry
representatives and local stakeholders (for details see Appendix A)
8.1.2 All consultee responses on the Diver Management Plan should be
based on the mitigation requirements, as detailed in this outline plan
and comments raised that are not relevant to the mitigation plan will
not be taken into consideration by the MMO.
8.1.3 The MMO’s consultation on the Diver Management Plan will have a
deadline response date of 4 weeks and comments received after this
date will be considered at the discretion of the MMO.
8.1.4 Further detail on the construction timetable and design elements,
such as foundation type and installation methods will be detailed in
the final plan.
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9. Appendix A: List of Consultees
9.1.1 This Appendix lists the main industry and local stakeholders who will
be consulted upon the drafting of the final Diver Management Plan.
This list is not final or exclusive and additional stakeholders can be
included if they make a request in writing to the project. Full contact
details, including email addresses, will be supplied to the MMO for
each organisation listed.
9.1.2 The consultees are:
NBDL Diving Liaison Officer;
BSAC;
National Diving Officer and Safety & Development Manager.
PADI;
PADI Diving Society Manager.
Health and Safety Executive;
Local Dive Businesses;
Divers Down.
Swanage Boat Charters.
Charter boat businesses involved in the disruption agreement
process.
Additional dive businesses / stakeholders that make themselves
known to the project.