NAVITUS BAY WIND PARK · Organisation (MMO). The appropriateness of the final required mitigation...

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



Page ii Appendix 14


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



Appendix 14 Page iii


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



Page iv Appendix 14


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



Appendix 14 Page 1


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.



Page 2 Appendix 14


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.



Appendix 14 Page 3


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



Page 4 Appendix 14


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



Appendix 14 Page 5


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).



Page 6 Appendix 14


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


impacts

Popular dive sites

Proposed mitigation

measures

Benefits to the diving community

British Sub- Aqua Club Meeting and presentation

January 2014


impacts

Proposed mitigation

measures

Benefits to the wider

diving community

Education and research opportunities



Appendix 14 Page 7


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



Page 8 Appendix 14


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.



Appendix 14 Page 9


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.



Page 10 Appendix 14




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



Appendix 14 Page 11




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.



Page 12 Appendix 14


Figure 6.1 – Diving Locations



Appendix 14 Page 13


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:



Page 14 Appendix 14


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.



Appendix 14 Page 15


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.



Page 16 Appendix 14


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.



Appendix 14 Page 17


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.

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