alexandra basin redevelopment project

Alexandra Basin Redevelopment ProjectHabitats Directive AssessmentNatura Impact Statement

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DOCUMENT CONTROL SHEET

Client: Dublin Port Company

Project Title: Alexandra Basin Redevelopment

Document Title: Habitats Directive Assessment – Natura Impact Statement

Document No: D01

This Document Comprises:

DCS TOC Text No. of Appendices List of Figures List of Tables

1 1 69 5 1 1

Alexandra Basin Redevelopment Project

Natura Impact Statement

Alexandra Basin Redevelopment & Capital Dredging Natura Impact Statement

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TABLE OF CONTENTS 1 INTRODUCTION ........................................................................................................................ 1

1.1 BACKGROUND TO THE REQUIREMENTS FOR APPROPRIATE ASSESSMENT ............................ 1

1.2 OVERVIEW OF DUBLIN PORT COMPANY AND THE REDEVELOPMENT PROPOSAL .................. 2

1.3 LEGISLATIVE CONTEXT ..................................................................................................... 4

1.3.1 Appropriate Assessment Requirements and Methodology .............................. 4

1.4 CONSULTATION................................................................................................................ 8

2 APPROPRIATE ASSESSMENT SCREENING OF THE PROJECT ....................................... 11

2.1 DESCRIPTION OF THE PROJECT ...................................................................................... 11

2.1.1 Site location and layout .................................................................................. 11

2.1.2 Overview of the project elements – works phase ........................................... 11

2.1.3 Operational Phase .......................................................................................... 18

2.2 SCREENING OF THE NATURA 2000 SITES WITHIN THE STUDY AREA ................................... 18

2.2.1 Natura 2000 Sites within the study area of the proposal ............................... 19

2.2.2 Identification of Natura 2000 sites potentially affected by the project ............ 24

2.2.3 Overview of the Natura 2000 sites potentially affected .................................. 28

2.3 IDENTIFICATION OF POTENTIAL SIGNIFICANT IMPACTS ....................................................... 33

2.3.1 Direct, Indirect or Secondary Impacts ............................................................ 33

2.4 DISCUSSION AND CONCLUSION OF THE SCREENING STAGE .............................................. 36

3 APPROPRIATE ASSESSMENT .............................................................................................. 37

3.1 STAGE 2 ........................................................................................................................ 37

3.2 IMPACT PREDICTION FOR NATURA 2000 SITES ................................................................. 37

3.2.1 Potential impacts affecting the North Dublin Bay cSAC ................................. 37

3.2.2 Potential impacts affecting the South Dublin Bay cSAC ................................ 40

3.2.3 Potential impacts affecting the Rockabill to Dalkey Island cSAC ................... 42

3.2.4 Potential impacts affecting the North Bull Island SPA.................................... 45

3.2.5 Potential impacts affecting the South Dublin Bay & Tolka Estuary SPA........ 47

3.3 POTENTIAL EFFECTS ON THE CONSERVATION OBJECTIVES OF THE NATURA 2000 SITES .... 51

3.3.1 Potential effects on the Conservation Objectives of the North Dublin Bay

cSAC .............................................................................................................. 51

3.3.2 Potential effects on the Conservation Objectives of the South Dublin Bay

cSAC .............................................................................................................. 52

3.3.3 Potential effects on the Conservation Objectives of the Rockabill to Dalkey

Island cSAC .................................................................................................... 52

3.3.4 Potential effects on the Conservation Objectives of the North Bull Island SPA .

........................................................................................................................ 53

3.3.5 Potential effects on the Conservation Objectives of the South Dublin Bay &

Tolka Estuary SPA ......................................................................................... 54

3.4 MITIGATION MEASURES FOR THE PROTECTION OF NATURA 2000 SITES .............................. 55

3.4.1 Mitigation measures for the North Dublin Bay cSAC ..................................... 55


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3.4.2 Mitigation measures for the South Dublin Bay cSAC ..................................... 56

3.4.3 Mitigation measures for the Rockabill to Dalkey Island cSAC ....................... 56

3.4.4 Mitigation measures for the North Bull Island SPA ........................................ 58

3.4.5 Mitigation measures for the South Dublin Bay & Tolka Estuary SPA ............ 58

3.5 ASSESSMENT OF IN COMBINATION EFFECTS WITH OTHER PLANS OR PROJECTS .................. 58

3.6 RESIDUAL EFFECTS ON THE CONSERVATION OBJECTIVES OF NATURA 2000 SITES ............ 61

3.6.1 Conservation objectives of the North Dublin Bay cSAC ................................ 61

3.6.2 Conservation objectives of the South Dublin Bay cSAC ................................ 62

3.6.3 Conservation objectives of the Rockabill to Dalkey Island cSAC .................. 62

3.6.4 Conservation objectives of the North Bull Island SPA ................................... 63

3.6.5 Conservation objectives of the South Dublin Bay & Tolka Estuary SPA ....... 63

4 NIS CONCLUSION .................................................................................................................. 67

5 REFERENCES ......................................................................................................................... 69


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List of Figures

Figure 1.1 Dublin Port Company Land Holdings ..................................................................................... 2

Figure 2.1 Overview of the proposed works areas within the Alexandra Basin and Navigation Channel & Dispoal Site ........................................................................................................................................ 11

Figure 2.2 Overview of the proposed Works in Alexandra Basin West ................................................ 13

Figure 2.3 Dredge Material Locations within Alexandra Basin and the Liffey Channel ........................ 15

Figure 2.4 Overview of the proposed Berth 52 / 53 Works ................................................................... 16

Figure 2.5 Natura 2000 sites located within 15km of Alexandra Basin Redevelopment, including proposed channel dredging and disposal site. ...................................................................................... 23

Figure 2.6 Natura 2000 sites within the zone of influence of the proposed redevelopment works at Alexandra Basin and the associated capital dredging scheme and disposal site. ................................ 29

List of Tables

Table 1.1 Consultees which formed part of the statutory consultation ................................................ 9

Table 2.1 Natura 2000 sites within the study area of the proposed Alexandra Basin Redevelopment and Capital Dredging Scheme ........................................................................................... 20

Table 2.2 Identification of Natura 2000 sites potentially affected by the proposed Alexandra Basin Redevelopment, Capital Dredging Scheme and disposal of dredge material at the Burford Bank ................................................................................................................................... 25

Table 2.3 Qualifying Interests of the North Dublin Bay cSAC ........................................................... 30

Table 2.4 Special Conservation Interests of the North Bull Island SPA ............................................ 31

Table 2.5 Special Conservation Interests of the South Dublin Bay & Tolka Estuary SPA ................ 32

Table 2.6 Potential Direct, Indirect and Secondary Impacts of the Port Development and Operations on Natura 2000 Sites ......................................................................................................... 35

Table 3.1 Special Conservation Interests of the North Bull Island SPA and the frequency of occurrence within the Dublin Port Shipping Channel ............................................................................................... 46

Table 3.2 Special Conservation Interests of SPAs and the frequency of occurrence within the Dublin Port Shipping Channel ........................................................................................................................... 47

Table 3.3 Summary of the potential impacts, mitigation and residual impacts identified for the Natura 2000 designations within the zone of influence of the proposed Alexandra Basin Redevelopment and associated capital dredging. ................................................................................ 64


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Appendices

Appendix A AVIAN IMPACT ASSESSMENT (NAIRN, 2014)

Appendix B MARINE MAMMALS IMPACT ASSESSMENT (CRONIN & JESSOPP, 2014)

Appendix C COASTAL PROCESSES MODELLING (RPS, 2014)

Appendix D NPWS NATURA 2000 SITE SYNOPSES

Appendix E SCREENING ASSESSMENT (STAGE 1) TO IDENTIFY THE POTENTIAL FOR SIGNIFICANT

EFFECTS IN THE ABSENCE OF MITIGATION TO THE ROCKABILL TO DALKEY ISLAND

(CSAC)


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1 INTRODUCTION

1.1 BACKGROUND TO THE REQUIREMENTS FOR APPROPRIATE ASSESSMENT

With the introduction of the Birds Directive in 1979 and the Habitats Directive in 1992 came the

obligation to establish the Natura 2000 network of sites of highest biodiversity importance for rare and

threatened habitats and species across the EU. In Ireland, the Natura 2000 network of European sites

comprises Special Areas of Conservation (SACs), candidate SACs, Special Protection Areas (SPAs),

and proposed SPAs. Areas are selected for designation as SACs for the conservation of Annex I

habitats (including priority types which are in danger of disappearance) and Annex II species (other

than birds). Areas are selected for designation as SPAs for the conservation of Annex I birds and other

regularly occurring migratory birds and their habitats. The annexed habitats and species for which

each site is selected correspond to the qualifying interests of the sites; from these the conservation

objectives of the site are derived. A key protection mechanism is the requirement to consider the

possible nature conservation implications of any plan or project on the Natura 2000 site network

before any decision is made to allow that plan or project to proceed.

All proposed developments that require planning permission or other development consent, whether

carried out by private, local authority or State developers, including ordinarily exempted development

within or affecting a Natura site, or which could potentially have a significant effect on a Natura 2000

site, are subject to Appropriate Assessment by a competent authority.

The obligation to undertake appropriate assessment derives from Article 6(3) of the Habitats Directive,

in particular. The first test is to establish whether, in relation to a particular plan or project, appropriate

assessment (abbreviated to AA in this document) is required. This stage is termed “AA screening”,

and its purpose is to determine, on the basis of a preliminary assessment and objective criteria,

whether a plan or project, alone and in combination with other plans or projects, could have significant

effects on a Natura 2000 site in view of the site‟s conservation objectives. It is necessary to apply the

precautionary principle in making any key decisions in relation to the tests of AA. Therefore, where

significant effects are likely, uncertain or unknown at screening stage, AA will be required.

AA is a focused and detailed impact assessment of the implications of the plan or project, alone and in

combination with other plans and projects, on the integrity of a Natura 2000 site in view of its

conservation objectives. Data and information on the project and on the site and an analysis of

potential effects on the site must be obtained and presented in a Natura Impact Statement (NIS).

Ecological specialists will be required to undertake the surveys, research and analysis, with input from

other experts (e.g. hydrologists or engineers) as necessary to prepare the NIS. It is the responsibility

of the proponent of the plan or project to have the NIS prepared for submission to the competent

authority or authorities.


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This document is an NIS and comprises information in support of a Stage 2 Appropriate Assessment,

which will be conducted by An Bord Pleanála, and follows the completion of the Stage 1 Screening for

Appropriate Assessment undertaken in respect of the consideration of the proposed Alexandra Basin

Redevelopment and associated Capital Dredging Scheme.

1.2 OVERVIEW OF DUBLIN PORT COMPANY AND THE REDEVELOPMENT PROPOSAL

Dublin Port, owned and operated by Dublin Port Company (DPC), is a key facilitator of merchandise

trade in and out of Ireland and has a critical role in the national, regional and local economy. Dublin

Port is also a key component of the national tourism sector and is a major gateway for visitors to

Ireland. The principal activity of DPC is the provision of infrastructure to facilitate the safe and efficient

flows of goods and passengers through the port. DPC owns approximately 260ha of land at the mouth

of the River Liffey Estuary where it flows into Dublin Bay (Figure 1.1). The current land holdings

contain facilities operated by the port users including Roll-On, Roll-Off (Ro-Ro) terminals, cruise line

operations, container terminals, bulk loading and unloading operations and bulk liquid handling,

storage and facilities. In 2013, these facilities processed 29 million gross tonnes of freight and 1.7

million passengers (on a combination of ferries and cruise ships).

Figure 1.1 Dublin Port Company Land Holdings


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The Dublin Port Masterplan was published in 2012 to present a vision for future operations of the Port

by reference to developments in merchandise trade and key sectors of the economy. It also examined

the existing land utilisation at Dublin Port and presented options for future development of the Port to

facilitate handling of 60 million gross tonnes by 2040 coupled with growing cruise ship trade and the

requirement to accommodate larger ships. A comprehensive Strategic Environmental Assessment and

Strategic Natura Impact Statement (for the purposes of Appropriate Assessment) of the Masterplan

were also prepared to accompany and inform the Masterplan. The Masterplan is a non-statutory plan

but has been explicitly endorsed in government policy, specifically in the National Ports Policy of 2013.

The Strategic Natura Impact Statement (SNIS) undertaken as part of the Masterplan process outlines

the strategic approach to mitigation for those impacts identified and provides a framework within which

Appropriate Assessments for individual projects can be undertaken. This Natura Impact Statement

(NIS) takes account of the findings of the SNIS and provides a project-focussed assessment of

impacts with regard to all Natura 2000 sites within the zone of influence of the proposed development.

The proposed project evaluated in this NIS incorporates the requirements of DPC to advance the first

phase of the Masterplan by way of the Alexandra Basin Redevelopment (ABR) Project which

incorporates:

1. The redevelopment of Alexandra Basin West

2. The redevelopment of the basin at Berths 52/53

3. A capital dredging scheme to enable larger vessels to access the Port.

Alexandra Basin West

Dismantling and removal of infrastructure and infill material

Quay wall refurbishment/construction (designed to accommodate future dredging to a

level of -15m CD)

Installation of Ro-Ro ramps

Ro-Ro jetty construction

Dredging of the basin and berthing pockets to -10m Chart Datum (CD)

Treatment of contaminated dredged material and re-use for infill at Berths 53/53

Excavation and restoration of Graving Dock No.1

Infilling of Graving Dock No.2 with treated dredged material

Relocation of ore concentrates loading system to a westwards extension of Alexandra Quay

West Berths 52 / 53

Dismantling and removal of existing infrastructure

Infilling of Berths 52 / 53 basin with treated dredged material for land reclamation


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Raising of existing surface levels by 1.4m

Quay wall construction

Mooring jetty construction

Installation of a Ro-Ro ramp

Navigation Channel

Dredging of Liffey Channel to -10m CD, from East Link Bridge to the Dublin Bay Buoy,

disposal of uncontaminated dredged material at Burford Bank (subject to permit)

Construction of a surge protection / retaining wall at the Poolbeg Marina

1.3 LEGISLATIVE CONTEXT

Articles 6(3) and 6(4) of the Habitat Directive 92/43/EEC require an Appropriate Assessment of plans

to prevent significant adverse effects on Natura 2000 sites.

Article 6(3) Any plan or project not directly connected with or necessary to the management of the site

but likely to have a significant effect there on either individually or in combination with other plans or

projects, shall be subject to appropriate assessment of its implications for the site in view of the site’s

conservation objectives. In the light of the conclusions of the assessment of the implications for the

site and subject to the provisions of paragraph 4, the competent national authorities shall agree to the

plan or project only after having ascertained that it will not adversely affect the integrity of the site

concerned and if appropriate, after having obtained the opinion of the general public.

Article 6(4) If, in spite of a negative assessment of the implications for the site and in the absence of

alternative solutions, a plan or project must nevertheless be carried out for imperative reasons of

overriding public interest, including those of social or economic nature, the Member State shall take all

compensatory measures necessary to ensure that the overall coherence of the Nature 2000 site is

protected. It shall inform the Commission of the compensatory measures adopted.

The purpose of AA is for the competent authority to assess whether the proposed works in Dublin Port

will adversely affect the integrity of the Natura 2000 sites concerned. It should be highlighted at this

stage in the process that an application under Article 6(4) is highly unlikely given the overall design of

the project has been undertaken in such a way as to avoid any construction directly within a Natura

2000 site

1.3.1 Appropriate Assessment Requirements and Methodology

Thus, Article 6(3) of the Habitats Directive requires that any plan or project likely to have significant

effects on a Natura 2000 site must undergo the process of Appropriate Assessment. Proposed plans

or projects can only be approved if it has been ascertained that they will not adversely affect the


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integrity of the Natura 2000 site(s) concerned or, in the case of a negative assessment where there

are no alternative solutions, the scheme can only be approved for imperative reasons of overriding

public interest. This Natura Impact Statement has been prepared to inform the Appropriate

Assessment process to be undertaken by the competent authorities and will accompany the planning

application for the proposed ABR Project (and the separate but related applications for a licence to

dredge and for a Dumping at Sea permit application to the EPA following the findings of the initial

Screening Statement).

According to European Commission guidance on the provisions of Article 6(3) and (4) and rulings of

the Court of Justice of the European Union, the assessment requirements of Article 6 establish a

stage-by-stage approach as follows:

Stage 1 - Screening for a likely significant effect: An initial assessment of the project or plans effect

on a European site(s). If it cannot be concluded that there will be no significant effect upon a European

site, an AA is required;

Stage 2 - Appropriate Assessment (based on a Natura Impact Statement or NIS): Member States

are required to carry out an appropriate assessment of the implications for a protected site of a plan or

project when there is a likelihood that the plan or project will have a significant effect on that site

Where a plan or project not directly connected with or necessary to the management of a site is likely

to undermine the site‟s conservation objectives, it must be considered likely to have a significant effect

on that site. The assessment of that risk must be made in the light of, in particular, the characteristics

and specific environmental conditions of the site concerned by such a plan or project. Following the

aforesaid appropriate assessment, a competent authority may allow such a plan or project to be

authorised on condition that it will not adversely affect the integrity of the site concerned.

Stage 3 – Assessment of alternative solutions: The process which examines alternative ways of

achieving the objectives of the project or plan that avoid adverse impacts on the integrity of the Natura

2000 site.

Stage 4 – Assessment where no alternative solutions exist and where adverse impacts remain:

An assessment of compensatory measures where, in the light of an assessment of imperative reasons

of overriding public interest (IROPI), it is deemed that the project or plan should proceed.

Each stage determines whether a further stage in the process is required. If, for example, the

conclusions at the end of Stage One are that there will be no significant impacts on the Natura 2000

site, there is no requirement to proceed further.

In complying with the obligations under Article 6(3) and following the EC Guidance, Managing Natura

2000 Sites, and DEHLG Guidance (2010), this Natura Impact Statement has been structured as


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described below; taking account of the conclusions of the initial Screening Report (RPS, 2013). The

Screening Report concluded that an Appropriate Assessment would be required for the project, this

was verified further by the DAHG in their consultation response (Ref: G Pre00148/2013) which

outlined that the NIS should be submitted to their department upon completion.

Screening for Appropriate Assessment

Screening is the process that addresses and records the reasoning and conclusions in relation to the first two tests of Article 6(3), namely:

whether a plan or project is directly connected to or necessary for the management of the site, and

whether a plan or project, alone or in combination with other plans and projects, is likely to

have significant effects on a Natura 2000 site in view of its conservation objectives.

Thus, the initial Screening determines whether the project is likely to have significant effects on any

Natura 2000 site. A detailed list of all cSACs and SPAs within the study area (taking account of sites

within a 15km radius, with reference to the zone of influence of the proposal) was compiled and the

qualifying interest features for each site identified. Following this, the key environmental conditions

(conservation objectives) needed to support site integrity were detailed for each site. According to the

NPWS guidance (DEHLG, 2010) the initial Screening stage determines whether Appropriate

Assessment is necessary, according to the requirements of Article 6(3) by examining:

Whether a plan or project can be excluded from AA requirements because it is directly

connected with or necessary to the management of a Natura 2000 site;

Whether a plan or project, alone or in combination with other plans and projects, is likely to

have significant effects on a Natura 2000 site in view of its conservation objectives; and

If the effects are deemed to be significant, potentially significant, or uncertain, or it the

screening process becomes overly complicated, then the process must proceed to Stage 2

(AA), which comprises the preparation of a Natura Impact Statement (NIS) to inform the

Appropriate Assessment process.

Screening for Appropriate Assessment involves the following:

Description of plan or project

Identification of relevant Natura 2000 sites, and compilation of information on their qualifying

interests and conservation objectives

Assessment of likely effects – direct, indirect and cumulative – undertaken on the basis of

available information as a desk study or field survey or primary research as necessary

Screening Statement with conclusions


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Stage 2 Appropriate Assessment

This stage of the assessment process considers the predicted impacts (whether they are direct,

indirect, short term, long term, constructional, operational or cumulative in conjunction with other plans

or projects) arising from the proposed project with regard to the integrity of Natura 2000 sites and their

conservation objectives. EC Guidance (Managing Natura 2000 Sites) states that the integrity of a site

involves its ecological functions and the decision as to whether it is adversely affected should focus on

the site‟s conservation objectives (EC 2000). Moreover, the Court of Justice of the European Union

has held that, in order for the integrity of a site as a natural habitat not to be adversely affected, the

site needs to be preserved at a favourable conservation status.

The Appropriate Assessment, which is contributed to by this NIS, comprises four elements (DEHLG,

2010):

Information required, where the conservation objectives of the Natura 2000 sites potentially

affected are reviewed and the aspects of the proposed project which affect these conservation

objectives are identified.

Impact Prediction, where the likely impacts of the project are examined. These include

direct/indirect, short/long term, construction/operational/decommissioning, isolated, interactive

and cumulative effects.

Conservation Objectives, where the effects of a project or plan are assessed as to whether

they have any adverse effects on the integrity of the site as defined by its conservation

objectives.

Mitigation Measures, where the level of mitigation (top of mitigation hierarchy) is assessed

against the adverse effects that the project or plan is likely to cause. These are measures

aimed at minimising, cancelling out or ideally avoiding the negative impact of the proposal

before, during or after its completion or implementation.

Conclusion, Identifies potential adverse impacts of the plan or project on the Natura 2000 sites

and explains how those effects will be avoided through mitigation; a timescale and

requirements for the delivery of mitigation measures are set out. The Conclusion must include

a statement (as required by rulings of the Court of Justice of the European Union) whereby the

competent authority has ascertained beyond reasonable scientific doubt that the proposal will

not, alone or in combination with other plans or projects, have an adverse effect on the

integrity of any Natura 2000 site. Moreover, the competent authority will have to be satisfied

that, in order for the integrity of a site as a natural habitat not to be adversely affected, the site

needs to be preserved at a favourable conservation status.


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1.4 CONSULTATION

The planning application in respect of the ABR Project stems from DPC‟s Masterplan which was

adopted in 2012, after an extensive consultation process and the completion of a non-statutory SEA

and a Strategic Natura Impact Statement. As part of the initial consultation process, for the application

by DPC to An Bord Pleanála for planning permission for the ABR Project, a series of consultations

were undertaken at various stages in the preparation of both Environmental Impact Statement (EIS)

and the Natura Impact Statement (NIS); and associated licence and permit applications relating to the

proposed development. The following provides a summary of the consultations undertaken and the

submissions and observations on such consultations which have served to inform the development of

this NIS:

Pre-application high-level stakeholder briefings with the NRA, NPWS, DCC, Fáilte Ireland,

NTA carried out by DPC;

Meeting with elected members of DCC (Central Area Committee DCC, North Central Area

Committee) carried out by DPC;

Pre-application consultations with An Bord Pleanála pursuant to section 37B of the Planning

and Development Act 2000, as amended;

Public consultation in relation to the proposed development and community gain proposal

being advanced as part of the application.

As part of the overall consultation process in relation to the proposed development, consultation letters

together with a description of the project were issued to all relevant statutory and non-statutory

consultees, in order to informally scope the information to be submitted in relation to the proposed

development and to ensure all relevant issues are addressed. Whilst this stage of consultation

stemmed from the requirements of the codified Environmental Impact Assessment Directive and

Ireland‟s EIA regulations, the opportunity to consult on the issued to be considered in the context of an

Appropriate Assessment under the Habitats Directive was also taken at the same time. Accordingly,

consultees were invited to make submissions or observations on information pertinent to both the EIA

and the AA processes. Responses were received from those bodies italicised in Table 1.1.


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Table 1.1 Consultees which formed part of the statutory consultation

Consultee List

Department of Communications, Energy and Natural Resources

Department of Education and Skills

Department of Transport, Tourism and Sport Department of Jobs, Enterprise and Innovation

Environmental Protection Agency Department of Foreign Affairs and Trade

Department of Arts, Heritage and the Gaeltacht Department of Health

An Comhairle Ealaion Development Applications Unit, DAHG (Underwater Archaeology and Nature Conservation)

An Taisce Electricity Supply Board

Birdwatch Ireland Eircom

Bord Gáis Eireann Health Service Executive

Bord Iascaigh Mhara Geological Survey of Ireland

Inland Fisheries Ireland (Blackrock) Heritage Council

Dublin Regional Authority Irish Rail

Inland Fisheries Ireland HQ Marine Institute

Coillte Irish Whale and Dolphin Group

Commissioners of Irish Lights Waterways Ireland

Department of Agriculture, Food and the Marine Radiological Protection Institute of Ireland

Health and Safety Authority RNLI

Failte Ireland Dublin City Council

Office of Public Works National Transport Authority

National Roads Authority

Where possible, all key responses, comments, recommendations and feedback from the initial

meetings and briefing sessions have been incorporated, as relevant, into the preparation of this NIS.

While all submissions received were considered during the preparation of the NIS of particular

relevance to the issues arising on the AA to be conducted by the competent authority are the

submissions from the Development Applications Unit (DAU) of the Department of Arts, Heritage and

the Gaeltacht (National Parks & Wildlife Service (NPWS)) and the Irish Whale and Dolphin Group.

Consultations on the Screening Statement

A copy of the ABR Project Screening Statement was also issued to the Development Applications Unit

of the Department of Arts, Heritage and the Gaeltacht (NPWS) on 26th June 2013 as follow-on from

the scoping and consultation process for the Department‟s review and comment. A response from the

Nature Conservation Unit was received on the 2nd July 2013 indicating that a copy of the Natura

Impact Statement should be issued to the Department for consideration upon completion.


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Consultations in relation to Stage 2 Appropriate Assessment

Following the initial screening for Appropriate Assessment and the decision to undertake Stage 2, a

consultation meeting with Dr David Lyons, Marine Ecologist, NPWS was held on 14th August 2013 to

discuss in particular the potential significant effects to the Qualifying Interest Features of the

surrounding cSACs. This meeting served to confirm the inclusion of the relatively newly-designated

Rockabill to Dalkey Island cSAC for which the Harbour Porpoise is a qualifying feature and also to

advise on the inclusion of the dredging and dumping at sea elements within one overall Natura Impact

Statement. In order to avoid any issues pertaining to “project splitting”, RPS on behalf of its client DPC

took the decision to include all elements of the ABR Project (including the redevelopments of

Alexandra Basin West, the basin at Berths 52/53 and the capital dredging and dumping of dredge spoil

at sea) all within one composite NIS.

A further consultation meeting was held on 8th November 2013 with Dr Linda Patton of NPWS to

discuss the Qualifying Interests of the SPAs within the surrounding area. This meeting served to

confirm the SPAs to be included in the Appropriate Assessment of the project together with the type of

predicted impacts in relation to the qualifying bird species of the SPAs identified.

Finally a Dumping at Sea pre-application consultation meeting was held with Mr Donal Grant of the

EPA. The key concerns in relation to the dredging of spoil from both the redevelopment of Alexandra

Basin West and the channel deepening were discussed. The need to assess, in significant detail, the

potential effects the dumping of dredge spoil within the Burford Bank and the issues which may arise

in relation to protected species was also highlighted. Finally, the EPA also confirmed its view that one

composite Natura Impact Statement should be prepared for the entire project as part of the Dumping

at Sea permit application.


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2 APPROPRIATE ASSESSMENT SCREENING OF THE PROJECT

2.1 DESCRIPTION OF THE PROJECT

2.1.1 Site location and layout

Dublin Port is situated on the estuary of the River Liffey which flows through the City of Dublin and

between the Great South Wall and the North Bull Wall before entering Dublin Bay. The Port Estate

comprises approximately 260ha of land at the mouth of the River Liffey. The ABR Project includes

work in two main areas of the Port, as well as dredging works within the navigation channel, as shown

in Figure 2.1.

Figure 2.1 Overview of the proposed works areas within the Alexandra Basin and Navigation

Channel & Dispoal Site

2.1.2 Overview of the project elements – works phase

Alexandra Basin West Redevelopment

The works proposed within Alexandra Basin West involve removal of infrastructure, quay wall

refurbishment, dismantling a section of the North Wall Quay Extension and dredging to facilitate the


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reconfiguration of operations within the basin. The existing layout of infrastructure in Alexandra Basin

West is shown in Figure 2.2. Proposed quay construction/refurbishment works include:

Refurbishment of existing quay walls along Ocean Pier West (approx 555m long)

Refurbishment of existing quay walls along Alexandra Quay West (approx 410m long)

Construction of new quay wall extension to Alexandra Quay West (approx 145m long)

Construction of new quay wall along Crossberth Quay (approx 255m long)

Installation of new mooring jetty for Ro-Ro berths (approx 300m long)

The anticipated form of construction for the quay walls within Alexandra Basin West will comprise a

steel combi-wall. This will consist of sheet piles extending between intermittent king piles. These king

piles will be either steel H-sections or tubular steel sections. The primary piles of front quay wall will be

installed to a depth determined by a combination of factors including; the local bedrock level, condition

of the bedrock, the condition of the overlying material, the imposed quay loadings and the final

geometry of the selected pile profile. It is proposed to construct new quay walls and structures over a

significant area of Dublin Port and it is anticipated that the bedrock level will vary to some degree

along the proposed quay lines. Based on available geotechnical information it is anticipated that the

primary piles of the new quay walls will be installed to depths ranging between -20m ODM and -35m

ODM, with the final depths depending on the local ground conditions and proximity to the standard

dredge depth. In areas of relatively shallow bedrock the piles will be cored into the rock as required to

achieve overall stability of the quay structure and to sustain any imposed loads. Intermediate sheet

piles forming quay walls will be installed to depths in excess of the standard dredge depth to protect

against undermining and loss of material from behind the quay wall. The final design and construction

depth of intermediate sheet piles will be determined by local material properties but will extend beyond

the dredge depth by 2-4m.

The quay wall will be tied to a sheet piled anchor wall or a reinforced concrete anchor beam, depending on the proximity of existing structures/operations to the quay side.

The berthing face to the quay structure will be formed by the installation of a reinforced concrete capping beam. Fenders will be fixed to the concrete capping beam to provide a suitable berthing face.

The deck behind the combi-wall quay will be reinstated to tie-in with the existing surfacing and deck levels.

The form of construction for the 273m long Ro-Ro jetty proposed for Alexandra Basin will be an open pile structure, constructed using a series of piled mooring dolphins, which will be connected using a steel walkway structure.


D01 13 Rev F01

Figure 2.2 Overview of the proposed Works in Alexandra Basin West

The proposals include the removal of an area of approximately 21,700m2 from the existing North Wall

Quay Extension to facilitate larger vessels. The scheme also involves the re-fronting of the existing

masonry walls with a steel combi-wall structure to facilitate dredging to -10m CD (and possible future

dredging to -15m CD). The following quay wall works are proposed:

Construction of a new quay wall along the basin side of North Wall Quay Extension, (approx

375m long)

Re-fronting of the remaining existing quay wall along the river side of North Wall Quay

Extension (approx 570m long)

The anticipated form of construction for these quay walls will comprise a steel combi-wall with a

reinforced concrete capping beam. Recesses will be formed in the quay walls to facilitate the

construction of bankseat structures for the installation of Ro-Ro ramps.


D01 14 Rev F01

It is proposed to remove an existing stockpile of infill material (approx 110,000m3) from the northwest

corner of Alexandra Basin West. This will be re-used for other construction activities within the Port. As

part of the overall conservation strategy for the scheme it is proposed to excavate and restore Graving

Dock No.1. This was previously infilled by Dublin Port Company with approximately 19,000m3 of clean

sand and capped with 1,000m3 of crushed concrete. It is envisaged that the excavated sand and

crushed concrete will be beneficially re-used for construction activities within the Port.

A dredge depth of -10m CD is proposed for Alexandra Basin West, however, the quay wall

infrastructure will be designed to facilitate possible future dredging to -15m CD. Approximately 0.47

million cubic metres of material must be removed from the basin to achieve -10m CD. Through earlier

samples taken for chemical testing, high levels of certain heavy metals have been found which require

appropriate consideration in this dredging; treating and disposal of this contaminated silt (see Figure 2.3). The dredged material recovered from Alexandra Basin West will, therefore, be treated and

transported by barge to a treatment facility adjacent to Berths 52/53 Basin. It will be stabilised and

modified to improve the engineering properties of the material, to allow its re-use as fill material for

reclamation works identified within the Port. As part of this scheme it is proposed to seal and fill

Graving Dock No. 2 at Alexandra Basin West to provide space for open hard standing space for

storage/parking and also to allow the westwards extension of Alexandra Quay West. It is envisaged

that approximately 55,000m3 of treated material will be required, which will be transported from the

treatment facility at Berths 52/53 to the Graving Dock No. 2 by trucks along DPC‟s internal road

network. The graving dock will be filled with treated material and capped with crushed material to tie in

with the surrounding surface levels. Consultations in relation to the dredging of this contaminated

material have taken place with the Marine Institute and the EPA to ensure all possible steps are taken

to prevent contamination to the wider environment, to prevent water quality issues or adverse effects

to the integrity of the Natura 2000 (or European) sites concerned (in view of those sites conservation

objectives).


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Figure 2.3 Dredge Material Locations within Alexandra Basin and the Liffey Channel

Berths 52/53 Basin

The works proposed at the Berths 52/53 Basin will involve the removal of existing infrastructure, quay

wall construction and infilling with treated dredge material to provide a large hard-standing area for

open storage. The existing infrastructure is shown in Figure 2.4. The following infrastructure is

proposed to facilitate the development:

Construction of a new quay wall to create a New Berth 52 (approx 300m long)

Construction of new 50m long mooring jetty for new Berth 52

Construction of new 50m long mooring jetty to extend existing Berth 49

As part of this scheme it is proposed to dredge a berthing pocket to -10m CD along the new quay wall,

however, the quay infrastructure will be designed to facilitate potential future dredging to -15m CD. It is

anticipated that a cellular cofferdam form of construction will be used to close off the Berth 52/53 Basin

from the main navigation channel. The existing bed level along the proposed line of the quay will be

excavated to competent material; the cells will then be constructed sequentially from the East side of

the Berth using interlocking sheet piles and filled with suitable granular material. The cells will be

constructed using piling plant, initially operating from the existing revetment and then from the

preceding cell in turn once completed. Fenders will be mounted on the Southern face of the


D01 16 Rev F01

cofferdams to provide a berthing face for the proposed Multi-Purpose Berth. Associated mooring and

berthing Dolphins will be installed to the East of the Berth to stabilise the existing revetment for

dredging operations.

Figure 2.4 Overview of the proposed Berth 52 / 53 Works

The form of construction for the mooring jetties proposed at New Berth 52 and Berth 49 will be an

open pile structure, constructed using a series of piled mooring dolphins, which will be connected

using a steel walkway structure. A two tier concrete ramp is also required to facilitate vehicular access

to vessels using the new river berth.

The dredged material recovered from Alexandra Basin West will be transported by barge to a

treatment facility adjacent to the Berths 52/53 Basin. It will be stabilised and modified to improve the


D01 17 Rev F01

engineering properties of the material, to allow its re-use as fill material for works identified within the

Port.

As part of this scheme it is proposed to infill the Berth 52/53 Basin to provide open storage space and

a new river berth at the port entrance. It is envisaged that approximately 400,000m3 of treated material

will be required for this infill.

The treatment facility will initially be positioned to the East of and immediately adjacent to the existing

Berth 53. The material will be removed from the barges, which will be surrounded by spill plates, at the

new cellular cofferdam and transported to the treatment site.

Navigation Channel Works

As part of the ABR Project, it is proposed to dredge the Liffey Channel to a level of -10m CD,

extending from East Link Bridge to the Dublin Bay Buoy. This equates to circa 5.9 million cubic metres

of dredging. In order to negate any potential impact of the channel dredging or the alterations to the

North Wall Quay Extension on the Poolbeg Marina, it is proposed to construct a circa 340m long surge

protection / retaining wall along the edge of navigation channel at Poolbeg Marina. This structure will

also serve to protect vessels moored in the marina from the wash produced by large vessels

manoeuvring about the North Wall Quay Extension. It is envisaged that the form of construction used

will be a steel combi-wall, as previously described. Stabilisation works may be required to the Great

South Wall to negate any impact from the channel dredging and realignment; these works may include

the placement of additional rock armour to protect the lower existing rock armour slopes around the

bull lighthouses to prevent any undermining of the existing structures. The steep channel side slopes

may require stabilisation by placing cable tied matting, tied back and supported at the top of the slope.

The following dredging will be undertaken as part of the proposed works:

Dredging of Alexandra Basin West to -10m CD

Dredging of the Liffey Channel to -10 CD from the East Link Bridge to the Dublin Bay Buoy.

The dredging will involve the removal of 3.2 million cubic metres of mainly fine sand in the

outer channel and 2.7 million cubic metres of mainly silty material from the inner channel.

The proposed dredging will permit access to Alexandra Basin West for the largest ships and will

provide deeper water depths for vessels. Preliminary consultations with the Marine Institute have

indicated that the heavily contaminated material is not suitable for disposal at sea. Therefore, it is

proposed that this material will be treated and re-used for infill within the Port. Under previous

dredging campaigns, DPC has been permitted to dispose of lightly contaminated material to a

designated sea disposal site with specific conditions (such as capping). It is therefore envisaged that

lightly contaminated material from the navigation channel, adjacent to Alexandra Basin West, is


D01 18 Rev F01

suitable for disposal at sea with cognisance of the conditions imposed with regard to previous

dredging and dumping at sea applications (Dumping at Sea Permit no S0004-01 was issued to DPC by

the Environmental Protection Agency (EPA) on the 28 July 2011). The disposal of the dredged material

will require a Dumping at Sea Permit from the EPA. The uncontaminated material from the channel will

be dredged to the required design depths by an excavator which will operate from a floating pontoon.

The dredged material will be loaded into barges and transported directly to the licensed sea disposal

site. It is envisaged that the dredging of uncontaminated material will be carried out during winter

months only (October to March). The rate of dredging of the main channel is determined by the

capacity of the disposal site to accommodate the material deposited and the length of dredging

season, typically six months per annum. Considering these two constraints, it is estimated that the

main channel dredging could be completed, given favourable conditions, within six years. The

preferred disposal strategy is to deposit the dredge material on the existing dump site to the west of

the Burford Bank (see Figure 2.5).

2.1.3 Operational Phase

The works associated with this scheme are required to permit a reconfiguration of the existing

operations within Alexandra Basin West and at the Berths 52/53 Basin. It is therefore envisaged that

all operations within these areas will be similar to the operations which are currently ongoing.

It is envisaged that the reclaimed infill area at Graving Dock No. 2 will require a suitable drainage

system. Storm water runoff from this site will be collected and passed into the existing storm water

drainage system. The storm water drainage system will collect rainwater for discharge to the harbour

waters via a series of silt traps and oil interceptors. The outfall pipe for the existing combined storm

sewer on the site will be extended through the proposed quay walls as part of the proposed works. A

new drainage system will be required for the newly shaped North Wall Quay Extension. This system

will include appropriate interceptors and will be discharged by outfalls through the new quay walls. The

reclamation area at the Berths 52/53 Basin will also require a new drainage system.

Any maintenance dredging of the channel which will be required in the longer term will be carried out

as part of DPC‟s regular maintenance dredging programme. The material generated would likely be

disposed of at sea at a licensed disposal site agreed in accordance with DPC‟s maintenance dredging

licence.

2.2 SCREENING OF THE NATURA 2000 SITES WITHIN THE STUDY AREA

This section provides an assessment of the Natura 2000 sites within the study area of the proposal; a

15km radius has been chosen as a precautionary measure, to ensure that all potentially affected

Natura 2000 sites are included in the screening process, which is in line with Appropriate Assessment

of Plans and Projects in Ireland – Guidance for Planning Authorities produced by the Department of

the Environment, Heritage and Local Government (2010). Following this guidance the proposed


D01 19 Rev F01

project was examined to establish whether it is likely to give rise to significant adverse effects on any

Natura 2000 site or sites. This was based on a preliminary impact assessment using best available

information and preliminary baseline assessments. Data sources included the NPWS Natura 2000

data, the Environmental Protection Agency (EPA) and in particular work undertaken by DPC to inform

the Masterplan process and its outputs which included an EIS and Strategic Natura Impact Statement.

DPC also had a wealth of information from previous ecological surveys and baseline data collection,

As a precaution, the Lambay Island cSAC (site code 000204) has also been included, despite this

site‟s location at approximately 18.5km from the proposed works within the Alexandra Basin but in the

interest of undertaking a robust appraisal.

2.2.1 Natura 2000 Sites within the study area of the proposal

Twenty-one Natura 2000 sites were identified within the study area of the proposed redevelopment; it

is important to note that a number of the cSAC and SPA designation boundaries overlap in places.

Table 2.1 lists the cSACs and SPAs that are within the study area for the Appropriate Assessment

screening of the development proposals; Figure 2.6 shows their locations in relation to the proposed

ABR Project works and the associated dredge material disposal dump site at the Burford Bank.


D01 20 Rev F01

Table 2.1 Natura 2000 sites within the study area of the proposed Alexandra Basin Redevelopment and Capital Dredging Scheme Site Code Site Name Features of Conservation Interest Distance from

Dublin Port Distance from Burford Bank disposal site

0210 South Dublin Bay cSAC

Mudflats and sandflats not covered by seawater at low tide [1140] Directly adjacent Distance: 7km

3000 Rockabill to Dalkey Island cSAC

Reefs [1170]; Harbour porpoise (Phocoena phocoena) [1351]

Distance: 4.5km Within this SAC

0206 North Dublin Bay cSAC

Mudflats and sandflats not covered by seawater at low tide [1140]; Annual vegetation of drift lines [1210]; Salicornia and other annuals colonizing mud and sand [1310]; Spartina swards (Spartinion maritimae) [1320]; Atlantic salt meadows (Glauco-Puccinellietalia maritimae) [1330]; Mediterranean salt meadows (Juncetalia maritimi) [1410]; Embryonic shifting dunes [2110]; Shifting dunes along the shoreline with Ammophila arenaria (white dunes) [2120]; Fixed coastal dunes with herbaceous vegetation (grey dunes) [2130]; Humid dune slacks [2190] Petalwort (Petalophyllum ralfsii) [1395]

Distance: 0.35km Distance:4.88km

0202 Howth Head cSAC

Vegetated sea cliffs of the Atlantic and Baltic coasts [1230]; European dry heaths [4030]

Distance: 4.7km Distance: 2.735km

0199 Baldoyle Bay cSAC

Mudflats and sandflats not covered by seawater at low tide [1140]; Salicornia and other annuals colonizing mud and sand [1310]; Spartina swards (Spartinion maritimae) [1320]; Atlantic salt meadows (Glauco-Puccinellietalia maritimae) [1330]; Mediterranean salt meadows (Juncetalia maritimi) [1410]


2193 Irelands Eye cSAC

Perennial vegetation of stony banks [1220]; Vegetated sea cliffs of the Atlantic and Baltic coasts [1230]


0205 Malahide Estuary cSAC

Mudflats and sandflats not covered by seawater at low tide [1140]; Salicornia and other annuals colonizing mud and sand [1310]; Spartina swards (Spartinion maritimae) [1320]; Atlantic salt meadows (Glauco-Puccinellietalia maritimae) [1330]; Shifting dunes along the shoreline with Ammophila arenaria (white dunes) [2120]; Mediterranean salt meadows (Juncetalia maritimi) [1410]; Fixed coastal dunes with herbaceous vegetation (grey dunes) [2130]


0204 Lambay Island cSAC

Reefs [1170]; Vegetated sea cliffs of the Atlantic and Baltic coasts [1230]; Grey seal (Halichoerus grypus) [1364]; Harbour seal (Phoca vitulina) [1365]

Distance: 18.5km Distance: 17km

000714 Bray Head cSAC Vegetated sea cliffs of the Atlantic and Baltic coasts [1230]; European dry heaths [4030]; Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco Brometalia) (*important orchid sites) [6210]

Distance:14.1km


D01 21 Rev F01

Site Code Site Name Features of Conservation Interest Distance from Dublin Port

Distance from Burford Bank disposal site

0713 Ballyman Glen cSAC

Petrifying springs with tufa formation (Cratoneurion) [7220]; Alkaline fens [7230] Distance:14.8km Distance: 14.5km

0725 Knocksink Wood cSAC

Petrifying springs with tufa formation (Cratoneurion) [7220]; Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae) [91E0]

Distance: 14.3km

1209 Glenasmole Valley cSAC

Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco Brometalia) (*important orchid sites) [6210]; Molinia meadows on calcareous, peaty or clavey-silt-laden soils (Molinion caeruleae) [6410]; Petrifying springs with tufa formation (Cratoneurion) [7220]

Distance:13.8km

2122 Wicklow Mountains cSAC

Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or of the Isoto-Nanojuncetea [3130]; Natural dystrophic lakes and ponds [3160]; Northern Atlantic wet heaths with Erica tetralix [4010]; European dry heaths [4030]; Alpine and Boreal heaths [4060]; Species-rich Nardus grasslands, on siliceous substrates in mountain areas (and submountain areas, in Continental Europe) [6230]; Blanket bog (*active only) [7130]; Siliceous scree of the montane to snow levels (Androsacetalia alpinae and Galeopsietalia ladani) [8110]; Calcareous rocky slopes with chasmophytic vegetation [8210]; Siliceous rocky slopes with chasmophytic vegetation [8220]; Old sessile oak woods with Ilex and Blechnum in British Isles [91A0] Otter (Lutra lutra) [1355]

Distance:12.8km

4006 North Bull Island SPA

Light-bellied Brent Goose (Branta bernicla hrota) [A046]; Shelduck (Tadorna tadorna) [A048]; Teal (Anas crecca) [A052]; Pintail (Anas acuta) [A054]; Shoveler (Anas clypeata) [A056]; Knot (Calidris canutus) [A143]; Oystercatcher (Haematopus ostralegus) [A130]; Golden Plover (Pluvialis apricaria) [A140]; Grey Plover (Pluvialis squatarola) [A141]; Sanderling (Calidris alba) [A144]; Dunlin (Calidris alpina) [A149]; Black-tailed Godwit (Limosa limosa) [A156]; Bar-tailed Godwit (Limosa lapponica) [A157]; Curlew (Numenius arquata) [A160]; Redshank (Tringa totanus) [A162]; Turnstone (Arenaria interpres) [A169]; Black-headed Gull (Larus ridibundus) [A179]; Wetlands & Waterbirds [A999]


4024 South Dublin Bay & River Tolka Estuary SPA

Light-bellied Brent Goose (Branta bernicla hrota) [A046]; Oystercatcher (Haematopus ostralegus) [A130]; Ringed Plover (Charadrius hiaticula) [A137]; Grey Plover (Pluvialis squatarola) [A140]; Knot (Calidris canutus) [A143]; Sanderling

Distance: 0 Distance: 5.6 km


D01 22 Rev F01

Site Code Site Name Features of Conservation Interest Distance from Dublin Port

Distance from Burford Bank disposal site

(Calidris alba) [A144]; Dunlin (Calidris alpina) [A149]; Bar-tailed Godwit (Limosa lapponica) [A157]; Redshank (Tringa totanus) [A162]; Black-headed Gull (Croicocephalus ridibundus) [A179]; Roseate Tern (Sterna dougallii) [A192]; Common Tern (Sterna hirundo) [A193]; Arctic Tern (Sterna paradisaea) [A194]; Wetlands & Waterbirds [A999]

4016 Baldoyle Bay SPA Light-bellied Brent Goose (Branta bernicla hrota) [A046]; Shelduck (Tadorna tadorna) [A048]; Ringed Plover (Charadrius hiaticula) [A137]; Golden Plover (Pluvialis apricaria) [A140]; Grey Plover (Pluvialis squatarola) [A141]; Bar-tailed Godwit (Limosa lapponica) [A157]; Wetlands & Waterbirds [A999]

Distance: 6km Distance:6.24km

4172 Dalkey Islands SPA

Roseate Tern (Sterna dougallii) [A192]; Common Tern (Sterna hirundo) [A193]; Arctic Tern (Sterna paradisaea) [A194]


4025 Malahide Estuary SPA

Great Crested Grebe (Podiceps cristatus) [A005]; Light-bellied Brent Goose (Branta bernicla hrota) [A046]; Shelduck (Tadorna tadorna) [A048]; Pintail (Anas acuta) [A054]; Goldeneye (Bucephala clangula) [A067]; Red-breasted Merganser (Mergus serrator) [A069]; Golden Plover (Pluvialis apricaria) [A140]; Oystercatcher (Haematopus ostralegus) [A130]; Grey Plover (Pluvialis squatarola) [A141]; Knot (Calidris canutus) [A143]; Dunlin (Calidris alpina) [A149]; Black-tailed Godwit (Limosa limosa) [A156]; Bar-tailed Godwit (Limosa lapponica) [A157]; Redshank (Tringa totanus) [A162]; Wetlands & Waterbirds [A999]

Distance: 10.6km Distance: 12km

4040 Wicklow Mountains SPA

Merlin (Falco columbarius) [A098]; Peregrine (Falco peregrinus) [A103] Distance: 13.1km

4113 Howth Head Coast SPA

Kittiwake (Rissa tridactyla) [A188] Distance: 7.3km Distance: 2.51km

4117 Ireland's Eye SPA Cormorant (Phalacrocorax carbo) [A017]; Guillemot (Uria aalge) [A199]; Herring Gull (Larus argentatus) [A184]; Kittiwake (Rissa tridactyla) [A188]; Razorbill (Alca torda) [A200]



D01 23 Rev F01

Figure 2.5 Natura 2000 sites located within 15km of Alexandra Basin Redevelopment, including proposed channel dredging and disposal site.


D01 24 Rev F01

2.2.2 Identification of Natura 2000 sites potentially affected by the project

The ABR Project is not directly connected with or necessary to the management of any of the Natura

2000 sites identified. Of the Natura 2000 sites within a 15km radius of the proposal, eight of these are

designated for qualifying features (habitats and species) for which there are no pathways or

connections for potential effects. In addition, An Board Pleanála Inspector‟s Report (Wyse, 2007) for

an earlier screening exercise for the Dublin Port Gateway proposal accepted that only one Natura

2000 site within the Dublin Bay area (South Dublin Bay & River Tolka Estuary SPA) was likely to be

subject to an impact from the proposed elements of the Gateway project at Dublin Port. In the interim,

however, the Rockabill to Dalkey Island cSAC has recently been designated for the protection of the

Annex I habitat „Reefs‟, in addition to the Annex II species Harbour porpoise, with pathways for

potential effects arising during the redevelopment works.

Table 2.2 sets out the designated sites and provides an overview of those sites for which pathways for

potential impacts are identified. A significant number of designations within the 15km area examined

were evaluated as not requiring further consideration, due to separation by distance and taking

account of the qualifying interests and conservation objectives; where no interaction with the proposal

is identified. As set out in Table 2.2, of the twenty-one Natura 2000 sites, seventeen are at a

considerable distance from the proposed works and will not be subject to any direct habitat loss and

are generally unlikely to be affected by disturbance (noise, vibration and lighting) due to the distance

from impact sources. The current appraisal considers that the most likely impact pathways would arise

via hydraulic pathways, with reference to potential sedimentation and pollution effects within Dublin

Bay potentially affecting those designated sites at a distance from the immediate works via sediment

transport processes. Further consideration is given to disturbance and underwater noise impacts

potentially affecting marine fauna. The appraisal and evaluation of significance has been informed by

the following specialist reporting:

Avifauna Impact Assessment (Nairn, 2014) (see Appendix A);

Marine Mammals Impact Assessment (Cronin & Jessop, 2014) (see Appendix B);

Additionally a review of the Alexandra Basin Redevelopment Project Environmental Impact Statement

(RPS, 2014) was undertaken, with specific reference to the appraisal undertaken for Coastal

Processes Modelling (Chapter 9) (See Appendix C) and Marine Benthos and Fisheries (Chapter 5);

relevant details from these chapters are reproduced in this NIS, where applicable.

Baldoyle Bay cSAC and Malahide Estuary cSAC are designated for intertidal habitats, dunes, salt

meadows and saltmarsh vegetation. The former was over 6km from the Alexandra Basin area and the

latter was 11km from this area. Whilst being designated for habitats that can potentially be affected by

sedimentation and water pollution, it is considered that the sites are far enough away from impact

sources and in locations such that they would not be subject to any likely significant effects.


D01 25 Rev F01

The Wicklow Mountains SPA is designated for terrestrial bird species and was screened out at the

screening, given the absence of pathways for impacts, with cognisance of the distance of separation

between the proposed works and this designated site. The coastal SPA sites in the wider study area

which are designated for waterbirds (including waders, gulls and terns), have the potential to be

connected to the proposed works via water quality impacts affecting the bird species. However, from a

review of the Coastal Processes Assessment undertaken for the ABR Project EIS (RPS, 2014), in

addition to the Avifauna Impact Assessment Report (Nairn, 2014) it is concluded that there would be

no impacts on those sites as a result of dredging activities, see Appendices C and A respectively.

Thus, it was determined at screening stage that sedimentation and pollution from dredging activities

would not have an impact on these Natura 2000 sites located at a greater distance from the current

proposal. Whilst bird species are mobile and therefore potentially susceptible to impacts, it was

identified that the distance from the development area and lack of an impact pathway indicated that

these SPAs would not be subject to any likely significant effects.

Table 2.2 Identification of Natura 2000 sites potentially affected by the proposed Alexandra Basin Redevelopment, Capital Dredging Scheme and disposal of dredge material at the Burford Bank

Site

Code Site Name Distance Potential pathways for impacts Further

assessment required

0206 North Dublin Bay cSAC

0.35km Taking account of the proximity of the proposed works to the qualifying interests of the site, there is the potential for significant effects arising.

0210 South Dublin Bay cSAC

Adjacent Taking account of the proximity of the proposed works to the qualifying interests of the site, there is the potential for significant effects arising.

0199 Baldoyle Bay cSAC

6.1km Designated for intertidal habitats. Taking account of the distance of separation and the character of the proposal no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Baldoyle Bay cSAC from the project.

0202 Howth Head cSAC

4.7km Designated for coastal terrestrial habitats, taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Howth Head cSAC from the project.

0205 Malahide Estuary cSAC

11.3km Designated for intertidal habitats. Taking account of the distance of separation and the character of the proposal no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Malahide Estuary cSAC from the project.

0204 Lambay Island cSAC

18.5km Designated for vegetated sea cliffs and „Reef‟ habitat. Taking account of the distance of separation and the character of the proposal no pathways for potential significant effects are identified. Also designated for Grey seal and Harbour seal populations; taking account of


D01 26 Rev F01

Site Code

Site Name Distance Potential pathways for impacts Further assessment

required distance no pathways for potential significant effects are identified (Cronin & Jessopp, 2014). Accordingly, there is no potential for significant effects on the Lambay Island cSAC from the project.

2193 Irelands Eye cSAC

7.2km Designated for coastal terrestrial habitats; taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Ireland‟s Eye cSAC from the project.

3000 Dalkey Island to Rockabill

cSAC

Within Taking account of the location of the proposed works within this site, there is the potential for significant effects arising from direct disturbance, in addition to indirect noise disturbance arising from proposed piling within the Port.

0714 Bray Head cSAC

14.1km Designated for coastal and terrestrial habitats; taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Bray Head cSAC from the project.

0713 Ballyman Glen cSAC

14.5km Designated for terrestrial conservation interests, taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Ballyman Glen cSAC from the project.

0725 Knocksink Wood cSAC

14.3km Designated for terrestrial conservation interests, taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Knocksink Wood cSAC from the project.

1209 Glenasmole Valley cSAC

13.8km Designated for terrestrial conservation interests, taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Glenasmole Valley cSAC from the project.

2122 Wicklow Mountains

cSAC

12.8 Designated for terrestrial conservation interests, taking account of distance no pathways for potential significant effects are identified. Accordingly, there is no potential for significant effects on the Wicklow Mountains cSAC from the project.

4006 North Bull Island SPA

0.4km Taking account of the proximity of the proposed works to the conservation interests of the site, there is the potential for significant effects arising.

4024 South Dublin Bay & River

Tolka Estuary SPA

Adjacent Taking account of the proximity of the proposed works to the conservation interests of the site, there is the potential for significant effects arising.


D01 27 Rev F01

Site Code

Site Name Distance Potential pathways for impacts Further assessment

required

4016 Baldoyle Bay SPA

6km Designated for wintering waterbirds. Taking account of distance no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Baldoyle Bay SPA from the project.

4025 Malahide Estuary SPA

10.6km Designated for wintering waterbirds. Taking account of distance no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Malahide Estuary SPA from the project.

4040 Wicklow Mountains

SPA

13.1km Designated for Annex I listed terrestrial raptor species. Taking account of distance no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Wicklow Mountains SPA from the project.

4113 Howth Head Coast SPA

2.51km Designated for breeding Kittiwake. Taking account of distance and the requirements of this species, no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Howth Head SPA from the project.

4117 Ireland's Eye SPA

6.7km Designated for breeding seabirds. Taking account of distance, no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Irelands Eye SPA from the project.

4172 Dalkey Islands SPA

5.18km Designated for passage of migrant tern species. Taking account of distance and the requirements of these species within the SPA, no pathways for potential significant effects are identified (Nairn, 2014). Accordingly, there is no potential for significant effects on the Dalkey Islands SPA from the project.

The proposed construction, development and operation of the elements associated with the ABR

Project and associated dredge material disposal at the Burford Bank, are considered to have the

potential for significant effects on the following designations, taking account of their qualifying interests

and conservation objectives:

North Dublin Bay cSAC;

South Dublin Bay cSAC;

Rockabill to Dalkey Island cSAC

North Bull Island SPA; and

South Dublin Bay & Tolka Estuary SPA


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2.2.3 Overview of the Natura 2000 sites potentially affected

The integrity of a Natura 2000 site (referred to in Article 6.3 of the EU Habitats Directive) is determined

based on the conservation status of the qualifying features of the cSAC or SPA, and in order for the

integrity of a site as a natural habitat not to be adversely affected, the site needs to be preserved at a

favourable conservation status. The qualifying features for each site have been obtained through a

review of the Conservation Objectives available from the NPWS, while the site synopses for these

designations are presented in Appendix D. This section describes, in brief, the five Natura 2000 sites

where likely significant effects resulting from the ABR Project are possible:



Rockabill to Dalkey Island cSAC;


South Dublin Bay & Tolka Estuary SPA.

Information was collated from the NPWS website and links to documents therein. The Screening

Assessment (RPS, 2013) prepared an impact assessment matrix for each of these designations,

except for the Rockabill to Dalkey Island cSAC. Initially the dumping of dredge spoil at the approved

dump site within the Rockabill to Dalkey cSAC was to be considered under a stand-alone Appropriate

Assessment. However, following further consultations with the EPA and the NPWS, it was decided to

include all elements of the project within one Natural Impact Statement. Therefore, a screening

assessment has been undertaken to evaluate the potential significant effects (in the absence of

mitigation) within the Rockabill to Dalkey cSAC and is included in this NIS as it did not form part of the

original screening or Stage 1 assessment (see Appendix E). The location of these Natura 2000

designations in relation to the proposed works is presented in Figure 2.6.


D01 29 Rev F01

Figure 2.6 Natura 2000 sites within the zone of influence of the proposed redevelopment works at Alexandra Basin and the associated capital dredging scheme and disposal site.

North Dublin Bay cSAC (Site Code 000206)

This site covers the inner part of north Dublin Bay, the seaward boundary extending from the Bull Wall

lighthouse across to the Martello Tower at Howth Head. The North Bull Island is the focal point of this

site. This site is an excellent example of a coastal site with all the main habitats represented. The site

holds good examples of ten habitats that are listed on Annex I of the EU Habitats Directive; one of

these is listed with priority status and one Annex II species, petalwort (Petalophyllum ralfsii), a species

of liverwort, as set out in Table 2.3.

Several of the wintering bird species have populations of international importance, while some of the

invertebrates are of national importance. The site contains a numbers of rare and scarce plants

including some which are legally protected.


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Table 2.3 Qualifying Interests of the North Dublin Bay cSAC

Code Feature of Interest

Habitats

1140 Mudflats and sandflats not covered by seawater at low tide

1210 Annual vegetation of drift lines

1310 Salicornia and other annuals colonizing mud and sand

1320 Spartina swards (Spartinion maritimae)

1330 Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

1410 Mediterranean salt meadows (Juncetalia maritimi)

2110 Embryonic shifting dunes

2120 Shifting dunes along the shoreline with Ammophila arenaria (white dunes)

2130 Fixed coastal dunes with herbaceous vegetation (grey dunes)

2190 Humid dune slacks

Species

1395 Petalwort (Petalophyllum ralfsii)

The Conservation Objectives for the North Dublin Bay cSAC (NPWS, 2011) are described as: ‘To

maintain or restore the favourable conservation condition of the Annex I habitat(s) and/or the Annex II

species for which the cSAC has been selected‟ (NPWS, 2011a), as per the qualifying interests set out

in Table 2.3.

South Dublin Bay cSAC (Site Code 000210)

This site lies south of the River Liffey and extends from the South Wall to the west pier at Dun

Laoghaire. It is an intertidal site with extensive areas of sand and mudflats, a habitat listed on Annex I

of the EU Habitats Directive. The sediments are predominantly sands but grade to sandy muds near

the shore at Merrion Gates. There is a bed of Eelgrass (Zostera noltii) below Merrion Gates which is

the largest stand on the east coast. This site is a fine example of a coastal system with extensive sand

and mudflats, a habitat listed on Annex I of the EU Habitats Directive. The site has one Qualifying

Interest, the Annex I habitat „mudflats and sandflats not covered by seawater at low tide [1140]‟. The

area is also an important site for waterfowl.

The Conservation Objectives for the South Dublin Bay cSAC (NPWS, 2013) are described as: „To

maintain or restore the favourable conservation condition of the Annex I habitat for which the cSAC

has been selected’, i.e. ‘[1140] Mudflats and sandflats not covered by seawater at low tide’ (NPWS,

2013a).


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This site includes a range of dynamic inshore and coastal waters in the western Irish Sea. These

include sandy and muddy seabed, reefs, sandbanks and islands. This site extends southwards, in a

strip approximately 7 km wide and 40 km in length, from Rockabill, running adjacent to Howth Head,

and crosses Dublin Bay to Frazer Bank in south county Dublin. The site encompasses Dalkey,

Muglins and Rockabill Islands. The area selected for designation represents a key habitat for the

Annex II species harbour porpoise, within the Irish Sea. This site is of conservation importance for

Reefs, listed on Annex I, and Harbour Porpoise, listed on Annex II, of the EU Habitats Directive.

The Conservation Objectives for the Rockabill to Dalkey Island cSAC (NPWS, 2013) are described as:

‘To maintain or restore the favourable conservation condition of the Annex I habitat(s) and/or the

Annex II species for which the cSAC has been selected’, i.e. ‘[1170] Reefs’ and Harbour porpoise

(Phocoena phocoena) (NPWS, 2013b).

North Bull Island SPA

This site covers all of the inner part of north Dublin Bay, with the seaward boundary extending from the

Bull Wall lighthouse across to Drumleck Point at Howth Head. This Natura 2000 site is of international

importance on account of both the total number of waterfowl and the individual populations of light-

bellied Brent Goose, black-tailed godwit and bar-tailed godwit that use it. Also of significance is the

regular presence of several species that are listed on Annex I of the EU Birds Directive. The site has

18 Special Conservation Interests; 17 wintering bird species and a wetlands and waterbirds

assemblage, as set out in Table 2.4.

Table 2.4 Special Conservation Interests of the North Bull Island SPA

Code Species & Code

A046 Light-bellied Brent goose (Branta bernicla hrota)

A048 Shelduck (Tadorna tadorna)

A052 Teal (Anas crecca)

A054 Pintail (Anas acuta)

A056 Shoveler (Anas clypeata)

A130 Oystercatcher (Haematopus ostralegus)

A140 Golden plover (Pluvialis apricaria)

A141 Grey plover (Pluvialis squatarola)

A143 Knot (Calidris canutus)

A144 Sanderling (Calidris alba)

A149 Dunlin (Calidris alpina)

A156 Black-tailed godwit (Limosa limosa)


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Code Species & Code

A157 Bar-tailed godwit (Limosa lapponica)

A160 Curlew (Numenius arquata)

A162 Redshank (Tringa totanus)

A169 Turnstone (Arenaria interpres)

A179 Black-headed gull (Larus ridibundus)

A999 Waterbirds & wetlands

The Conservation Objectives for the North Bull Island SPA (NPWS, 2011) are described as: ‘To

maintain or restore the favourable conservation condition of the bird species listed as Special

Conservation Interests for this SPA’ (NPWS, 2011b), i.e. those species listed in Table 2.4.


The South Dublin Bay and River Tolka Estuary SPA comprises a substantial part of Dublin Bay. It

includes the intertidal area between the River Liffey and Dun Laoghaire, and the estuary of the River

Tolka to the north of the River Liffey, as well as Booterstown Marsh. A portion of the shallow marine

waters of the bay is also included. The site is important for wintering waterfowl, being an integral part

of the internationally important Dublin Bay complex. As an autumn tern roost, it is also of international

importance. Furthermore, the site supports a nationally important colony of Common Tern. The site

has 14 Special Conservation Interests including 13 bird species and a wetlands and waterbirds

assemblage. The Special Conservation Interests for the South Dublin Bay & River Tolka Estuary SPA

are presented in Table 2.5.

Table 2.5 Special Conservation Interests of the South Dublin Bay & Tolka Estuary SPA

Code Species & Code

A046 Light-bellied Brent goose (Branta bernicla hrota)

A130 Oystercatcher (Haematopus ostralegus)

A137 Ringed plover (Charadrius hiaticula)

A140 Grey plover (Pluvialis squatarola)

A143 Knot (Calidris canutus)

A144 Sanderling (Calidris alba)

A149 Dunlin (Calidris alpina)

A157 Bar-tailed godwit (Limosa lapponica)

A162 Redshank (Tringa totanus)

A179 Black-headed gull (Croicocephalus ridibundus)

A192 Roseate tern (Sterna dougallii)

A193 Common tern (Sterna hirundo)


D01 33 Rev F01

Code Species & Code

A194 Arctic tern (Sterna paradisaea)

A999 Waterbirds & wetlands

The Conservation Objectives for the South Dublin Bay & River Tolka Estuary SPA (NPWS, 2011) are

described as: ‘To maintain or restore the favourable conservation condition of the bird species listed

as Special Conservation Interests for this SPA’ (NPWS, 2011c), i.e. those species listed in Table 2.5.

2.3 IDENTIFICATION OF POTENTIAL SIGNIFICANT IMPACTS

2.3.1 Direct, Indirect or Secondary Impacts

Table 2.1 lists the Natura 2000 sites within 15km of the proposed development. None of the Natura

2000 site boundaries overlap with the ABR Project sites. The engineering design, upon which this

assessment has been carried out, have been set out to avoid any direct effects on designated Natura

2000 sites by way of avoiding works within any designated site. Only the proposed channel alignment

works and dredge material disposal require works in outer Dublin Bay which lie within the boundary of

the Rockabill to Dalkey cSAC, giving rise to the potential for direct effects with specific regard to

harbour porpoise.

A source – receptor – pathway approach has been used as part of this appraisal process. The

pathways identified were waterbodies linking the development areas to the identified cSACs and

SPAs; habitat loss; severance; modification and pollution to cSACs and habitats within SPAs; and the

potential for noise emissions and disturbance to impact on the identified cSAC and SPA sites.

The closest SPA to the proposed development areas is the South Dublin Bay and River Tolka SPA,

which is immediately adjacent or behind the Alexandra Basin development areas and to the south of

the development area. In addition, the North Bull Island SPA lies directly behind the South Dublin Bay

and River Tolka SPA and to the north of the proposed development area (see Figure 2.6). Given the

current nature of port operations and the use of Alexandra Basin West in particular by Brent Geese, it

can be assumed that bird species in particular have become habituated to the current noise levels and

operational disturbance. This is particularly prevalent through the opportunistic nature of the Brent

Geese in Alexandra Basin West where, for the first time in winter 2012/13, it became clear that this

was used as a regular feeding site by Brent Geese. The basin is filled with water at all times and the

geese frequently feed on spilt agricultural products on the quays when ships have finished unloading

(Natura, 2013).

However, should noise levels or disturbance through increased shipping exceed current levels, then a

potential for impact or disturbance to bird species through displacement and loss of feeding time could

potentially occur at the adjacent SPAs.


D01 34 Rev F01

The closest cSACs to the proposed development areas within the Dublin Port facility are the North

Dublin Bay cSAC and the South Dublin Bay cSACs. Changes in the hydrology and sediment regime of

port areas, as a result of capital dredging and the construction of quays, has the potential to result in

changes in the distribution of inter-tidal and sub-tidal habitats. An increase in future maintenance

dredging activities may also have an implication in terms of habitat loss for the Natura 2000 sites.

In addition, there is potential for habitat severance or fragmentation where dredging will be required in

the outer part of Dublin Bay (which overlaps with the Rockabill to Dalkey cSAC). This gives rise to the

potential for direct noise and physical disturbance impacts within the cSAC, arising from the dredging

works and disposal of dredge material at the Burford Bank site, which is also within the site

designation. There is further potential for indirect impacts affecting harbour porpoise with regard to

noise impacts emanating from the piling and construction activities at Dublin Port, in addition to water

quality effects from dredging activity resulting in increased turbidity, leading to temporary displacement

of this species within the cSAC.

Capital and maintenance dredging and dumping activities have the potential to result in an alteration to

water flow and the sedimentation regime. Changes in the hydrology and suspended sediments

therefore have the potential to affect the availability of prey to bird species listed as special

conservation interests of the adjoining SPA sites, through changes in turbidity, and through deposition

and scour of sediment which may affect the extent of inter-tidal and sub-tidal habitats. An appraisal of

the impacts of the proposed development with regard to coastal processes and hydrodynamics was

prepared to inform the Environmental Impact Statement (RPS, 2014) and is referred to in this NIS (at

Appendix C).

There is a risk of a release of pollutants during construction as a result of accidental spillages and site

run-off. During port operations, following the development works through increased shoreline activities

as well as increased ship movements, there may be an increased risk of pollution incidents.

Any future operations will need to ensure they meet the environmental quality standard (EQS)

established in the Environmental Objectives (Surface Water) Regulations (S.I. No. 272 of 2009), as

amended. Ensuring all discharges are appropriately licensed and codes of best practice are utilized

from design to construction and through to development will ensure that all operations will not impact

on the water quality in Dublin Bay and therefore, no significant potential impacts from pollution are

anticipated.

No other pathway has been identified by which any plan or project could have a significant „in

combination‟ effect with the ABR project on any of the Natura 2000 sites. Table 2.6 identifies the

potential direct, indirect and secondary impacts of the port operations on the Natura 2000 sites which

have been “screened–in” for potential effects from Dublin Port ABP development and subsequent

operations.


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Table 2.6 Potential Direct, Indirect and Secondary Impacts of the Port Development and Operations on Natura 2000 Sites Site Name Direct Impacts Indirect/

Secondary Resource

Requirements (Drinking Water Abstraction Etc.)

Emissions (Disposal to Land,

Water or Air)

Excavation Requirements

Transportation Requirements

Duration of Construction,

Operation, Decommissioning

North Dublin Bay cSAC

No impact on qualifying habitats or

species

Potential effects

(Pollution)


species

No impact on qualifying habitats

or species

Potential for habitat modification arising from dredging within

the navigation channel


Potential effects (Disturbance)

South Dublin Bay cSAC


Potential effects

(Pollution)






Potential effects (Disturbance)

Rockabill to Dalkey cSAC

Potential direct

disturbance impacts on

harbour porpoise

Potential effects on

water quality


species

Potential for increased

suspended solids emissions from dredging and

dredge material disposal to affect harbour porpoise

Potential habitat modification and disturbance from

dredging and dredge material disposal with

regard to Harbour porpoise

Potential disturbance

impacts affecting harbour porpoise

Potential disturbance effects on harbour porpoise


Potential direct impacts

from disturbance


water quality

No impact on Special

Conservation Interests






effects

Potential effects (Disturbance &/or

displacement)


Potential direct impacts

from disturbance


water quality








effects

Potential effects (Disturbance &/or

displacement)


D01 36 Rev F01

2.4 DISCUSSION AND CONCLUSION OF THE SCREENING STAGE

The first stage of the Habitats Directive appraisal process, ie screening, was completed in compliance

with the relevant European Commission and national guidelines. The conclusions set out in this section

of the NIS have been informed by the Screening Assessment undertaken by RPS (2013). Mitigation

measures were not considered as part of the Screening process and can only be taken into account in

the Appropriate Assessment Stage. The potential impacts during the construction and operation of the

activities associated with the ABR Project have been considered in the context of the Natura 2000 sites

potentially affected, their Qualifying Interests and conservation objectives. From the findings of the

Screening for Appropriate Assessment, it is concluded that the proposed project (as described in

Section 2.1.2, taking account of the preliminary engineering drawings and details available):

Is not directly connected with or necessary to the management of any Natura 2000 site;

Has the potential to give rise to significant effects on the qualifying interests of the three cSACs

and two SPAs outlined in (Section 2.2).

o North Dublin Bay cSAC;

o South Dublin Bay cSAC;

o Rockabill to Dalkey Island cSAC;

o North Bull Island SPA; and

o South Dublin Bay & Tolka Estuary SPA

Does not have the potential to affect the remaining cSAC and SPA sites identified in the wider

study area. These sites have therefore been screened out as discussed in Section 2.2.

Therefore adopting the precautionary approach, in line with current guidance, an Appropriate

Assessment of the proposal is required to be undertaken by the competent authorities based, inter

alia, on this NIS.


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3 APPROPRIATE ASSESSMENT

3.1 STAGE 2

This stage of the assessment process evaluates the entire proposal, taking account of the potential for

direct, indirect and cumulative impacts, alone or in combination with other plans and projects, affecting

the integrity of the Natura 2000 sites; in view of the conservation objectives, i.e. the structure and

function, of these designations. According to EC guidance for the management of Natura 2000 sites

(EC, 2000), and recent decisions of the CJEU, the integrity of a site involves its ecological functions and

the need to preserve the site at a favourable conservation status. Thus, any decision as to whether it is

adversely affected should focus on the site‟s conservation objectives and favourable conservation

status.

The preparation of this NIS has been informed by the surveys and specialist reports commissioned to

examine the potential for significant effects on the qualifying interests, conservation objectives and

conservation status of the Natura 2000 sites identified as being potentially affected by the proposal.

These reports included an „Avifauna Impact Assessment‟ (Nairn, 2014) (See Appendix A) and „Marine

Mammals Impact Assessment‟ (Cronin & Jessopp, 2014) (See Appendix B); further review of the

Environmental Impact Statement (EIS) prepared by RPS (2014) was undertaken, with particular regard

to coastal processes, where relevant modelling output is provided in Appendix C of the current report.

Key qualifying features for each Natura 2000 site under consideration are detailed in this NIS, with

regard to potential effects and this information was used to predict impacts and to establish whether the

project will give rise to adverse effects on the integrity of any Natura 2000 site.

3.2 IMPACT PREDICTION FOR NATURA 2000 SITES

3.2.1 Potential impacts affecting the North Dublin Bay cSAC

Potential impacts affecting Annex I habitats within the cSAC

The Annex I habitats for which this cSAC has been designated can be separated out on the basis of

coastal and terrestrial habitats and those occurring within the intertidal zone. The potential for adverse

effects arising from the proposal is evaluated as being limited to imperceptible and not significant with

regard to those habitats occurring within the terrestrial, coastal environment, these include:

Embryonic shifting dunes [2110]

Shifting dunes along the shoreline with Ammophila arenaria (white dunes) [2120]

Fixed coastal dunes with herbaceous vegetation (grey dunes) [2130]

Humid dune slacks [2190]


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The proposed redevelopment works at Alexandra Basin West, Berth 52/53 and associated dredging

and dredge material disposal is located at a distance from the above habitats and will therefore not

have the potential for direct effects.

Indirect impacts affecting these habitats will not occur, taking account of the distance between these

habitats and the proposed works. Furthermore, there are no pathways for negative effects, taking

account of the findings of the bathymetric and sediment transport modelling prepared as part of the

coastal processes impact assessment to inform the Environmental Impact Statement (Chapter 9)

prepared by RPS (2014). It is therefore concluded that there will be no alteration to coastal processes or

coastal habitats from the proposed channel dredging works.

In the absence of any indirect effects or interactions between the proposed works and these coastal

habitats it is evaluated that there would be no cumulative effects arising from the proposal that would

have the potential to affect the conservation status of these habitats.

The inter-tidal habitats listed as qualifying interest for this designation are as follows:

Mudflats and sandflats not covered by seawater at low tide [1140]

Annual vegetation of drift lines [1210]

Salicornia and other annuals colonizing mud and sand [1310]

Spartina swards (Spartinion maritimae) [1320]

Atlantic salt meadows (Glauco-Puccinellietalia maritimae) [1330]

Mediterranean salt meadows (Juncetalia maritimi) [1410]

The proposed works, located in Alexandra Basin West, the Berth 52/53 basin, North Wall Quay

extension, quay walls, surge protection, rock armouring/revetment at the Great South Wall and channel

dredging will not require the direct removal of any Annex I habitat area within the North Dublin Bay

cSAC. The potential for indirect effects on Annex I habitats, including mudflat and sandflats and inter-

tidal saltmarsh habitats is considered with regard to the potential for alteration of coastal processes

arising from the proposed works, with specific reference to the dredging works within Alexandra Basin

West and the navigation channel.

From a review of the hydrodynamic and coastal processes assessment prepared as part of the EIS for

the proposed works (RPS, 2014) the proposed channel dredging to -10mCD will not significantly alter

the tidal regime, wave climate or sediment transport regime in Dublin Bay, away from the immediate

area around the entrance channel at the approaches to the Bull walls and the harbour channels. The

coastal processes appraisal, including hydrodynamic modelling, is represented in Appendix C to inform

the competent authority‟s assessment. Morphological simulations have shown that the proposed

channel to

-10mCD is unlikely to be susceptible to rapid infilling and will have a similar stability to the existing


D01 39 Rev F01

channel. There will be an increased requirement for maintenance dredging at the inner end of the

harbour channel near the East Link Bridge due to the larger change in the water depths in this area

which will tend to lead to deposition of fluvial suspended sediments particularly during storm flow

events; this will be incorporated into the ongoing maintenance dredging operations at the port.

With regard to coastal processes and overall sediment budgets within the Port area, the Liffey Estuary

and the inner Bay including the North Dublin Bay cSAC, the dredging plume simulations indicate that

the deposition of material lost during the dredging of the channel at Alexandra Basin West will be mostly

contained within the inner harbour channel area. This will result in a deposition rate of less than 0.2

grams/ square metre which is equivalent to a deposition depth of less than 0.2µm.

From the investigations undertaken, the proposed material to be dredged comprises fine sand in the

approach channel and a silty material with a little coarse sediment in the harbour channels and berths.

The hydrodynamic study identifies that the silty material disposed at the Burford Bank site will be carried

away by the tide and largely dispersed. Sediment that is deposited around Dublin Bay is very small at a

maximum of about 0.1 gram per m2 i.e. a thickness of 0.1µm.

The dredging of the outer approach channel will result in no significant plume as the material is sand

with little or no fines. Virtually all of the sand stays on the dump site and is not carried away by the tide

alone. The existing dump site at the Burford Bank is fully dispersive for silty sediments. The fine sand

sediment can be moved under storm conditions and being similar to the existing bed material will

gradually be assimilated into the natural sediment transport regime.

The modelling predicts that over time, taking account of coastal process, the sand material removed

from the navigation channel will be removed from the dump site. Sand deposited on the site will be

assimilated into the general sedimentary budget of the Bay and thus the sand will not be lost to the

overall coastal processes of the greater Dublin Bay area. The proposed works result in no significant

change to the tidal regime away from the immediate vicinity of the proposed works. Thus it is concluded

that the development project proposed by DPC will have no significant impact on the existing tidal

regime in Dublin Bay away from the immediate area of the channel.

It will be seen that there is no significant difference in the wave heights away from the immediate area

around the channel for each of the north east, east and south east storm directions. Similar results have

been observed in the wave climate simulations run at mid and low tide levels, thus it can be concluded

that the proposed development will have no impact on the wave regime in the greater Dublin Bay area

away from the immediate vicinity of the approach channel.

The removal of dredge material from the navigation channel and disposal at the Burford Bank are not

shown to adversely impact on the sediment budget and deposition rates required within the inner bay

with regard to the maintenance of the Annex I intertidal habitats for which the cSAC is designated. This


D01 40 Rev F01

is evidenced from the modelling which shows the predominant tidal movements within the bay are north

to south (Appendix C); where there is limited tidal current velocities moving sediment from the Liffey

channel out to the slack water around the intertidal flats of the North Dublin Bay cSAC.

Potential impacts affecting Annex II species within the cSAC

The Annex II listed plant Petalwort is listed as a qualifying interest for this site. This species within the

North Dublin Bay cSAC occurs as an outlier within the favourable range of this species, where all other

records of this species within cSAC sites are from the southwest and western coasts (NPWS, 2013).

The location of the proposed redevelopment works at Alexandra Basin West, within the existing Berths

52/53 Basin and the associated channel dredging works and dredge material disposal do not overlap

with the dune slack and machair coastal habitat requirements of this species and there is, therefore, no

potential for direct effects. There are no suitable habitats occurring directly adjacent to or in close

proximity to the proposed works that would lead to pathways for potential indirect effects on this

species.

The potential for indirect effects on this species arising from alteration to coastal processes from the

proposed channel dredging works are evaluated and, with reference to the bathymetric and sediment

transport modelling prepared to inform the Environmental Impact Statement (RPS, 2014), it is

concluded that there is no potential for the proposed works to adversely affect the coastal dune slack

and machair habitat within the North Dublin Bay cSAC which supports this species. With regard to

cumulative or in-combination effects, there are no interactions arising from the proposal that would have

the potential to affect this species, taking account of the NPWS conservation status conclusion (NPWS,

2013), which confirms that there are no pressures singularly affecting the cSAC population of this

species. The conservation status of this species, taking account of the population, range and habitat,

will therefore not be affected.

3.2.2 Potential impacts affecting the South Dublin Bay cSAC


The potential direct, indirect and cumulative impacts affecting the following Annex I habitat within the

cSAC are considered:

Mudflats and sandflats not covered by seawater at low tide [1140]

The proposed works, located within Alexandra Basin West, at the Berth 52/53 Basin, North Wall Quay

Extension, quay walls, surge protection, rock armouring/revetment at the Great South Wall and channel

dredging will not require the direct removal of any Annex I habitat area within the South Dublin Bay

cSAC. The potential for indirect effects on the intertidal Annex I mudflat and sandflats habitats is


D01 41 Rev F01

considered with regard to the potential for alteration of coastal processes arising from the proposed

works, with specific reference to the dredging works within the Alexandra Basin and the navigation

channel.

From a review of the hydrodynamic and coastal processes assessment prepared for the EIS (RPS,

2014) (included as Appendix C) the proposed channel dredging to -10mCD will not significantly alter the

tidal regime, wave climate or sediment transport regime in Dublin Bay away from the immediate area

around the entrance channel at the approaches to the Bull walls and the harbour channels.

Morphological simulations have shown that the proposed channel to -10mCD is unlikely to be

susceptible to rapid infilling and will have a similar stability to the existing channel. It is considered likely

that there will be an increased requirement for maintenance dredging at the inner end of the harbour

channel near the East Link Bridge due to the larger change in the water depths in this area which will

tend to lead to deposition of fluvial suspended sediments particularly during storm flow events; this will

be incorporated into the ongoing maintenance dredging operations at the port.

With regard to sediment budgets within the Port area, the Liffey Estuary and the inner Bay including the

South Dublin Bay cSAC, the preliminary dredging plume simulations indicate that the deposition of

material lost during the dredging of the channel at Alexandra Basin will be mostly contained within the

inner harbour channel area; resulting in a deposition rate of less than 0.2 grams/m2, which is equivalent

to a deposition depth of less than 0.2µm.

From the investigations undertaken the proposed material to be dredged comprises fine sand in the

approach channel and a silty material with a little coarse sediment in the harbour channels and berths.

The hydrodynamic study identifies that the silty material disposed at the Burford Bank site will be carried

away by the tide and largely dispersed. Sediment that is deposited around Dublin Bay is very small at a

maximum of about 0.1 gram/m2 i.e. a thickness of 0.1µm.

The dredging of the outer approach channel will result in no significant plume as the material is sand

with little or no fines. Virtually all of the sand stays on the dump site and is not carried away by the tide

alone. The existing dump site at the Burford Bank is fully dispersive for silty sediments. The fine sand

sediment can be moved under storm conditions and, being similar to the existing bed material, will

gradually be assimilated into the natural sediment transport regime.

The modelling shows that over time, taking account of coastal process, the sand material removed from

the navigation channel will be assimilated into the general sedimentary budget of the Bay and thus the

sand will not be lost to the overall coastal processes of the greater Dublin Bay area. The proposed

works result in no significant change to the tidal regime away from the immediate vicinity of the

proposed works. Thus it is concluded that the development project proposed by Dublin Port will have no

impact on the existing tidal regime in Dublin Bay away from the immediate area of the channel.


D01 42 Rev F01

It will be seen that there is no significant difference in the wave heights away from the immediate area

around the channel for each of the north east, east and south east storm directions. Similar results have

been observed in the wave climate simulations run at mid and low tide levels, thus it can be concluded

that the proposed development will have no impact on the wave regime in the greater Dublin Bay area

away from the immediate vicinity of the approach channel.

The coastal processes modelling shows that the removal of dredge material from the navigation

channel and disposal at the Burford Bank will not adversely impact on the sediment budget and

deposition rates required within the inner bay with regard to the maintenance of the Annex I intertidal

habitats, for which the cSAC is designated (RPS, 2014). This is evidenced from the modelling (see Appendix C) which shows the predominant tidal movements within the bay are north to south; where

there is limited tidal current velocities moving sediment from the Liffey channel out to the slack water

around the intertidal flats of the South Dublin Bay cSAC.

Overall, given no potential for significant effects have been identified for any of the Qualifying Interest

Features of the cSAC in isolation therefore no potential for in-combination or cumulative effects arise.

3.2.3 Potential impacts affecting the Rockabill to Dalkey Island cSAC


From the marine benthic surveys undertaken to inform the EIS (RPS, 2014) the material to be dredged

consists of fine muddy sands and fine sands, and is typical of the benthos found across a large area of

Dublin Bay. Recovery of the benthic communities in this area will commence immediately following

cessation of dredging and is expected to take about two years. The overall size of the Rockabill to

Dalkey Island cSAC is approximately 27,316 hectares; therefore the temporary disturbance to the

benthic community is less than 0.25% of the area of the cSAC and would be considered „not significant‟.

This coupled with the temporary nature of the impact source, means the expected impacts would be

considered negative, though minor and temporary in extent. In addition, the Annex I „Reef‟ habitats

listed as a qualifying interest of this site were not identified in or adjacent to the works area. Accordingly,

there will be no adverse effect on the integrity of the Annex I „Reef‟ (or any other) priority habitat from

the dumping of dredge spoil at sea within the cSACwith reference to the qualifying interests and

conservation interests of the designation.

Ebb and flood tide movements in the study area are predominantly in a south to north and north to

south direction respectively. Tidal velocities are highest at Howth Head and south at Dalkey Island and

predictive modelling undertaken for the proposed development (see model simulations in Appendix C)

demonstrates that the tidal regime will not be affected.

The average suspended sediment concentration over the dredging period peaks at about 75mg/l in the

shipping channel. Due to the presence of significant contamination, the dredging of Alexander Basin


D01 43 Rev F01

West will be undertaken using silt curtains around the dredging plant and no over-spill will be allowed on

the barges. The dredging of the channel outside Alexandra Basin West and the remaining sections of

the inner channel will result in plumes from the fine material lost during the dredging process. Some of

this material may also have low levels of contaminants. During disposal of silt at the Burford Bank dump

site, it is considered that the maximum increase of suspended solids will be concentrated to within the

Burford Bank area.

From the sediment transport modelling undertaken (see model simulations in Appendix C) it can be

seen that the principal direction of movement is due north/south, in line with the existing tidal flows. The

predominant tidal movement, therefore, will keep the siltation levels moving offshore, parallel to the

coast, at a distance from the reef habitat. The highest tidal velocities are at the Howth Head and Dalkey

Island reef habitat areas, thus precluding the potential for significant sedimentation on these exposed to

moderately exposed intertidal and sub-tidal reef habitats, as concluded in the benthic ecology impact

assessment prepared for Chapter 5 of the EIS (RPS, 2014).

Potential impacts affecting Annex II species within the cSAC

A specialist marine mammals impact assessment (Cronin & Jessopp, 2014) has been prepared to

inform the Appropriate Assessment to be undertaken by the competent authority); this report is

presented in Appendix B. Sightings of Europe‟s smallest cetacean species, the harbour porpoise, have

been relatively common off all coasts of Ireland and in the Irish Sea (Northridge et al., 1995; Hammond

et al., 1995; Pollack et al., 1997; Berrow et al., 2001; Ó Cadhla et al., 2004; Anderwald et al., 2011).

The small size of harbour porpoises and their erratic surfacing behaviour can make them difficult to

detect; there are however relatively frequent sightings of the species within Dublin Bay, including the

dredge disposal site and shipping channel (IWDG, 2013). Surveys of harbour porpoise carried out at

specific sites around the Irish coast identified Dublin Bay as an important area for the species, with high

densities in Dublin Bay of 1.19 per km2 reported, representing one of the highest densities of the

species recorded in Ireland to date (Berrow et al., 2008). Surveys of cetaceans in the waters outside of

Dublin Bay, in the western Irish Sea, indicated that harbour porpoise were by far the most abundant

species in the area with relative abundance of harbour porpoise estimated at 0.55 porpoise per km2

(Berrow et al., 2011). Sighting rates of harbour porpoise, and thus local densities, were notably higher

adjacent to Rockabill and Lambay Islands. This was consistent with Berrow et al. (2008) who recorded

high densities during smaller scale harbour porpoise surveys in the same area. This suggests that this

could be a good habitat for harbour porpoises. The Rockabill to Dalkey Island cSAC is designated for

the conservation and protection of this species. The most westerly section of the dredging within the

shipping channel and the dredge material dump site at the Burford Bank overlaps with this cSAC site

boundary.

The potential effects of demolition works, piling, dredging and dumping on marine mammals in general

include:


D01 44 Rev F01

Physical injury or death of individuals resulting from collisions with operator vessels.

Physical injury or death of individuals resulting from close-range exposure to pile-driving noise.

Chronic hearing damage or disturbance/displacement as a result of piling or dredging noise.

Consumption of contaminated prey items resulting from contaminants entering the food chain

(this is only a problem where contaminated substrates are disturbed).

Temporary impact on marine mammals‟ visibility should they intersect the sediment plume

during the dumping of dredged material.

Changes in prey availability due to local changes in benthic ecology caused by accumulation of

dredge spoil on the seabed.

The following impact assessment is taken from the findings of the Cronin and Jessopp (2014) impact

assessment report (Appendix B), where the proposed development and dredging of the channel within

the harbour and bay are evaluated as being unlikely to cause detectable impacts on cetaceans at the

population level. However it is considered that, as Dublin Bay is an important area for harbour porpoise,

there is the potential for impacts at a more localised level. The noise levels from dredging activities are

unlikely to cause hearing damage to exposed cetaceans provided they do not approach the immediate

vicinity of operations and have the opportunity to leave the affected area. As the received sound

pressure levels from dredging can exceed 140dB re1μPa at 1 km distance from the source, a value that

is detectable by harbour porpoise and as this is likely to extend to the cSAC, appropriate mitigation

measures will be required (Cronin & Jessopp, 2014).

Temporary threshold shift (TTS), a temporal elevation of the hearing threshold due to noise exposure,

could be induced by exposure to pile-driving noise. According to a literature review carried out by

Cronin & Jessopp (2014) a radius for the zone of behavioural response to pile-driving noise is identified

as up to at least 20km for harbour porpoises. Applying a broadband sound pressure level of 229dBrms

re1µPa at 1m scaled up by 10dB for larger diameter piles, the resulting TTS-zone for harbour porpoise

is estimated as 1.8km. Since the nearest point of the cSAC designated for harbour porpoise is outside

this range, the likelihood of population-level impacts from TTS is considered insignificant, and effects on

individual cetaceans entering the works area will be insignificant if appropriate mitigation measures are

carried out. However, pile driving and industrial noise can adversely impact behaviour, communication

and breeding. At 9kHz this noise is capable of masking strong dolphin vocalizations within 10-15km and

weak vocalizations up to approximately 40km; behavioural modifications have been observed in

bottlenose dolphins in response to noise produced by pile driving, and the abundance of echo-locating

harbour porpoise was found to decrease during pile driving activities in Denmark within 15 km of the

construction site. However, it remained inconclusive if the abundance changes were directly attributable

to the construction activities or were related to overall temporal variation in abundance. More recent

data from the field indicate that porpoise would react to pile driving at received sound exposure levels of

approximately 140dB reµPa2s. Source levels of broadband sheet piling (smaller piles) can be expected

to be reduced to 140dB SEL at a distance of between approximately 2-25 km, although this represents

only a rough estimate and will be very site and context specific (Cronin & Jessopp, 2014). These


D01 45 Rev F01

examples demonstrate the potential for impacts at a scale that overlaps with the cSAC. Considering the

potential for indirect impacts of pile driving and industrial noise on cetaceans, in particular harbour

porpoise, appropriate mitigation measures will be required to reduce the potential for significance of

effects.

Sediment plumes may present habitat disturbance to local cetaceans foraging in the area. The dredging

and dumping of material, particularly of fine sand and silt, will likely effect water quality and create a

plume effect which will travel according to local water currents. This may have a temporary impact on

marine mammals‟ visibility, particularly in the immediate vicinity of the vessel. As with seals, the dredged

area is not considered (or known to be) an important cetacean foraging area and therefore any

displacement resulting from impacts on available prey are unlikely and not considered significant

(Cronin & Jessopp, 2014).

The dump site on Burford Bank is in an open body of water approximately six nautical miles from

Alexandra Basin and two nautical miles outside Dublin Bay in about 20m water depth. The site overlaps

with the Rockabill to Dalkey Island cSAC, where harbour porpoise is listed as a qualifying interest. The

main tidal currents in the area of the Burford Bank are in a north-south direction, away from the intertidal

areas of Dublin Bay. The dumping of large quantities of dredged material may cause adverse effects on

local harbour porpoise populations. Porpoises feed mainly on small shoaling fishes, with many prey

items taken on or close to the benthos. The disposal site has been used for dredge spoil disposal for

several decades, with the benthos and demersal fish species subject to periodic smothering, and the

dump site is not a known „hotspot‟ for harbour porpoise foraging. Data on the distribution of cetacean

species from January 2009-July 2011 show only a single harbour porpoise sighting in the vicinity of the

Burford Bank with a more inshore/coastal distribution of harbour porpoise and bottlenose dolphin.

Therefore, any displacement resulting from impacts on available prey are unlikely and not considered to

be significant (Cronin & Jessopp).

3.2.4 Potential impacts affecting the North Bull Island SPA

Potential direct impacts affecting the SPA

The potential for direct impacts affecting this SPA site are unlikely as no works are proposed to occur

directly within the site boundary. There will be no direct habitat loss or direct disturbance to wintering

bird species listed as Special Conservation Interests of the SPA.

Potential indirect impacts affecting the SPA

An Avifauna Impact Assessment report (Nairn, 2014) has been prepared to inform the Appropriate

Assessment to be undertaken by the competent authority; this report is presented in Appendix A.

Populations of wintering Brent geese, associated with the SPA population, have been recorded


D01 46 Rev F01

frequenting the quays at Alexandra Basin West, feeding on spilt grain (mainly on Berths 29 to 31 and on

Ocean Pier West). For most of each day, a large flock is present swimming within the Basin (mean 126,

peak 450 birds recorded in January to April 2013). When there is no disturbance on the quayside, the

geese fly up to feed intensively on the agricultural products. Up to 450 geese were counted on Ocean

Pier in late December 2013, exceeding the threshold for an internationally or nationally important site.

While ships are unloading at the quays in Alexandra Basin West, the geese do not feed on the quay but

most revert to feeding on nearby grassland. As the only attraction for the geese in Alexandra Basin

West is the source of food in the agricultural products, they are likely to occur wherever these cargos

are offloaded in the future.

Wintering waders and waterbirds using the Tolka Estuary during low tide periods are known to move to

the lagoons within the North Bull Island SPA during the high tide period. The sum of peak counts for all

species in the estuary in 2012/13 was 18,900 birds. This was close to the average of the previous three

winters (19,080 birds). The total number of birds wintering in the entire area of Dublin Bay has been

relatively stable over the last decade.

In addition to Brent geese foraging within the Port, the shipping channel is also utilised by a number of

species listed as special conservation interests of the SPA site, recorded during bird surveys (Nairn,

2014), these species and frequency of occurrence are presented in Table 3.1.

Table 3.1 Special Conservation Interests of the North Bull Island SPA and the frequency of occurrence within the Dublin Port Shipping Channel

Species Frequency Activity within the channel

Light-bellied Brent Goose Infrequent Flying over the channel Shelduck Infrequent Flying over the channel

Teal Infrequent Flying over the channel Oystercatcher Infrequent Flying over the channel

Black-tailed Godwit Infrequent Flying over the channel Turnstone Infrequent Flying over the channel

It is considered that the infrequency and nature of the occurrence of these species within the shipping

channel, i.e. passing through and not utilising this area for foraging, reduces the potential for any

significant indirect effects on these species arising from dredging works or additional boat movements

within the shipping channel.

Model simulations were undertaken to investigate the suspension and distribution of the sediment

plume from the dredging of the harbour channel, as presented in the EIS for the proposal (RPS, 2014).

The modelling data indicated that neither the suspended sediment load in the water column nor the

deposition of the material from the plume will have a significant impact on the designated areas

adjoining Dublin Port; relevant modelling output is presented in Appendix C. The coastal processes

modelling and impact assessment prepared for the EIS (RPS, 2014) concluded that the proposed

capital dredging works will have no impact on the tidal regime or wave climate in the greater Dublin Bay


D01 47 Rev F01

area outside the immediate vicinity of the approach channel. The results also show that there will be no

significant impact on the sediment transport regime within Dublin Bay and estuary outside the approach

channel area as a result of the capital dredging scheme. From this conclusion, it is evaluated by Nairn

(2014) that there will be no significant impacts affecting the intertidal habitats (wetlands) which support

the wintering waders and water birds for which this site is designated.

The disposal of dredged material in the approved disposal site will take place entirely in the winter

months (October to March). The fine sediment elements of the dredged material are predicted to

disperse in a plume on each tide. Turbidity at the approved disposal site will be elevated as dumping at

this location is ongoing; however, suspended solids levels will return to background levels within a

period of days, following the completion of dumping in March each year. For the remainder of each

year the predicted concentrations of suspended sediment in the affected area will be low and would not

have any significant effect on the foraging ability of seabirds in this area during the period when they are

breeding within some of the nearby SPAs. There will thus be no residual effects on seabirds in the

following breeding seasons. It is concluded that the disposal of dredged material will have no significant

impacts on birds in the approved disposal area itself or in the surrounding parts of the Irish Sea.

3.2.5 Potential impacts affecting the South Dublin Bay & Tolka Estuary SPA

Potential direct impacts affecting the SPA

The potential for direct impacts affecting this SPA site are unlikely as no works are proposed to occur

directly within the site boundary. There will be no direct habitat loss or direct disturbance to wintering

bird species listed as Special Conservation Interests of the SPA.

Potential indirect impacts affecting the SPA

From the ornithological impact assessment (Nairn, 2014) an evaluation of the bird species listed as

special conservation interests for the SPA identified that only the Light-bellied Brent Goose, Black-

headed Gull and three tern species are regularly recorded within Dublin Port itself or in the shipping

channel, as presented in Table 3.2. Table 3.2 Special Conservation Interests of SPAs and the frequency of occurrence within the

Dublin Port Shipping Channel

Species Frequency Activity within the channel Light-bellied Brent Goose Infrequent Flying over the channel

Oystercatcher Infrequent Flying over the channel Roseate Tern Infrequent Flying over the channel Common Tern Frequent Roosting on navigation buoys

Arctic Tern Frequent Roosting on navigation buoys Black-headed Gull Frequent Foraging and roosting on jetties and navigation buoys


D01 48 Rev F01

Wintering birds

Brent Geese are present in Alexandra Basin West each winter from approximately November to April.

The geese are attracted to feed on spilt agricultural products on the quays, mainly on Berths 30 to33.

They also swim in flocks on the water in the Basin. These birds move frequently between different parts

of Dublin Bay and the species is one of the qualifying interests of the two Special Protection Areas in

Dublin Bay. Numbers of geese recorded in Alexandra Basin West peaked at 450 birds in both winters

2012/13 and 2013/14. The Tolka Estuary is the nearest intertidal area to the Alexandra Basin West and

to the fairway for shipping entering the Basin. The estuary is not covered in the monthly IWeBS counts

as these are normally concentrated during the high tide period when most of the estuary is covered by

water and the majority of the birds have moved to the Bull Island lagoons (Nairn, 2014).

Redevelopment of the quays and jetties in the Basin will take place on a phased basis so that shipping

can continue to use parts of the Basin at all times. As agricultural products will continue to be unloaded

here, albeit in different locations, the geese will continue to be attracted to the spillages. They are

already habituated to high levels of shipping activity and associated noise so that construction noise is

unlikely to have any additional effects. The geese will tolerate vehicles to a distance of less than 20m so

it is likely that they will not be disturbed by construction vehicles. While the geese do swim on the

surface of the Basin, they do not feed while on the water. They will thus not be exposed to

contaminated sediments during the dredging operations. It is therefore concluded that there will be no

significant impact of the proposed redevelopment works at Alexandra Basin West on wintering Brent

Geese.

Monitoring of birds in the Tolka Estuary has been undertaken, on behalf of DPC, over the four winters

2009/10 to 2012/13. The total number of birds wintering in the entire area of Dublin Bay has been

relatively stable over the last decade, although a decline was recorded in 2010/11 for the first time since

2003/04; the Tolka Estuary is thus a very important sub-site, especially at low tide, when it holds the

majority of all the birds in Dublin Bay.

There are no significant intertidal areas within the Berth 52/53 Basin. This is a confined deep water area

and does not hold any significant numbers of birds in winter. The basin will be fully contained within a

new steel pile wall prior to reclamation. This will prevent any escape of fill material to the Liffey channel

or to the wider areas of Dublin Bay. Thus, no significant impacts on wintering birds are predicted.

All birds using Dublin Port shipping channel and approaches are habituated to high levels of shipping

activity. Maintenance dredging was carried out in the channel in 2012 and no significant changes in bird

populations in the Tolka Estuary area in winter 2012/13 were recorded that could be connected with the

dredging activity. There will be no significant additional disturbance involved in the proposed capital

dredging for this project potentially affecting wintering waders and waterbirds within the shipping


D01 49 Rev F01

channel. Dredging of the proposed channel to -10mCD will not significantly alter the tidal regime, wave

climate or sediment transport regime in Dublin Bay away from the immediate area around the entrance

channel at the approaches to the Bull walls and the harbour channels. The proposed channel to

-10mCD is unlikely to be susceptible to rapid infilling and will have a similar stability to the existing

channel. It is therefore concluded that there will be no significant impacts of the dredging on

surrounding intertidal areas within Dublin Bay, either in the short-term or long-term. There will thus be

no indirect effects on foraging wintering wading birds in these locations.

A review of the impacts of capital and maintenance dredging in the Tamar estuary in south-west

England was published by Widdows et al. (2007). This estuary is a Special Protection Area under the

EU Birds Directive which requires annual maintenance dredging as well as occasional capital dredging

for new installations. Maintenance dredging here involves annual removal of between 5,000 and

200,000 tonnes of dry sediment per year. During two periods of capital dredging in the Tamar, the

amount of sediment dredged was between 500,000 and 700,000 tonnes per year. Annual estimates for

ten species of wildfowl and waders were analysed over several decades in the Tamar Estuary. There

were no significant correlations between overwintering bird numbers and dredging activity. Declines in

Teal and Wigeon over 30 years were related to milder winters which changed the migratory patterns of

these species.

It is concluded that the capital dredging of the shipping channel will have no significant impacts on

wintering birds in the channel itself or in the surrounding intertidal areas of the Tolka Estuary within the

SPA.

Breeding birds

Dublin Port has held a breeding colony of Common Terns (Sterna hirundo) and Arctic Terns (S.

paradisaea) since at least 1949 and this has been well-monitored since 1995. The terns breed mainly

on two mooring structures (known as the ESB and DPC dolphins) on the south side of the River Liffey,

near the Poolbeg power station. The birds are generally present on these structures from May to August

and numbers have been increasing steadily since the 1990s. Both species of terns can occasionally be

seen feeding in the wake of large ships entering and leaving the port. Terns are occasionally recorded

in Alexandra Basin but do not regularly feed there.

From June 2013 to January 2014 a series of six dedicated boat-based surveys of seabirds in the

shipping channel area was undertaken. The area covered was from Alexandra Basin West to the

outermost limit of dredged channel at the Dublin Bay Buoy. The most abundant species throughout the

surveys was Black-headed Gull with a peak of 665 in September. Common and Arctic Terns were

common in the port in June to August (the main breeding season) but were largely absent later on.


D01 50 Rev F01

The breeding tern colonies on the mooring dolphins in Dublin Port are sufficiently remote from

Alexandra Basin West (approximately 2km) and will not be directly affected by the redevelopment

works. Terns are rarely recorded flying within the Basin, as it is unlikely that their preferred fish prey

occurs here in sufficient density. The dredging of spoil from the Basin will not therefore have any

indirect impacts on breeding terns. As the proposed dredging of the navigation channel will take place in

winter months only (October to March inclusive), when the terns are absent, there will be no residual

increase in suspended sediments from dredging by the time the terns return to the colonies in late April.

Turbidity in the water of the shipping channel has the potential to increase marginally in the immediate

vicinity of the dredging works, which would have the implications for fish-eating birds including Terns,

which rely on sight to hunt. The majority of the nesting terns in Dublin Port rarely forage in the Liffey

channel but tend to fly out to shallower areas of Dublin Bay to catch the small shoaling fish on which

they prey. As the proposed dredging of the navigation channel will take place in winter months (October

to March inclusive), when the terns are absent, there will be no residual increase in suspended

sediments from dredging by the time the terns return to the colonies in late April.

Black-headed Gulls, listed as a special conservation interest for this designation, do not breed in the

Port and the large flocks that forage and roost in the Liffey channel will be unaffected by the proposed

capital dredging; where the seasonality of the dredging operations are limited to the winter months,

outside of the breeding season for this species. This species, therefore, will not be significantly affected

by the proposed works.

Due to the presence of significant contamination, the dredging of Alexandra Basin West will have to be

undertaken using silt curtains around the dredging plant and no over-spill will be allowed on the barges.

The dredging of the channel outside Alexandra Basin West and the remaining sections of the inner

channel will result in plumes from the fine material lost during the dredging process. Some of this

material may also have low levels of contaminants.

Model simulations were undertaken to investigate the suspension and distribution of the sediment

plume from the dredging of the harbour channel (RPS, 2014) which indicated that neither the

suspended sediment load in the water column nor the deposition of the material from the plume will

have a significant impact on the designated areas adjoining Dublin Port (see Appendix C). The coastal

processes modelling and impact assessment prepared for the EIS (RPS, 2014) concluded that the

proposed capital dredging works will have no impact on the tidal regime or wave climate in the greater

Dublin Bay area outside the immediate vicinity of the approach channel. The results also show that

there will be no significant impact on the sediment transport regime within Dublin Bay and estuary

outside the approach channel area as a result of the capital dredging scheme. From this conclusion, it is

evaluated that there will be no significant impacts affecting the intertidal habitats (wetlands) which

support the wintering waders and water birds for which this site is designated.


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The disposal of dredged material in the approved disposal site will take place entirely in the winter

months (October to March). The fine sediment elements of the dredged material are predicted to

disperse in a plume on each tide. Turbidity at the approved disposal site will be elevated as dumping at

this location is ongoing; however, suspended solids levels will return to background levels within a

period of days, following the completion of dumping in March each year. For the remainder of each year

the predicted concentrations of suspended sediment in the affected area will be low and would not have

any significant effect on the foraging ability of seabirds in this area during the period when they are

breeding within some of the nearby SPAs. There will thus be no residual effects on seabirds in the

following breeding seasons. It is concluded that the disposal of dredged material will have no significant

impacts on birds in the approved disposal area itself or in the surrounding parts of the Irish Sea.

3.3 POTENTIAL EFFECTS ON THE CONSERVATION OBJECTIVES OF THE NATURA 2000 SITES

3.3.1 Potential effects on the Conservation Objectives of the North Dublin Bay cSAC

The Conservation Objectives (NPWS, 2011) for this cSAC site are to maintain or restore the favourable

conservation condition of the Annex I habitat(s) and/or the Annex II species for which the cSAC has

been selected:

[1140] Mudflats and sandflats not covered by seawater at low tide

[1210] Annual vegetation of drift lines

[1310] Salicornia and other annuals colonizing mud and sand

[1330] Atlantic salt meadows (Glauco Puccinellietalia maritimae)

[1410] Mediterranean salt meadows (Juncetalia maritimi)

[2110] Embryonic shifting dunes

[2120] Shifting dunes along the shoreline with Ammophila arenaria ("white dunes")

[2130] * Fixed coastal dunes with herbaceous vegetation ("grey dunes")

[2190] Humid dune slacks

[1395] Petalophyllum ralfsii

Of the qualifying interests identified above, it has been evaluated that there are no pathways for impacts

(direct, indirect or cumulative) potentially affecting the terrestrial and coastal Annex I habitats and Annex

I species (Petalwort). Potential impacts identified in the current assessment with regard to the

conservation objectives of this site are therefore limited to impacts potentially affecting the intertidal

habitats listed as qualifying interests. Of these, taking account of the proposed works and the coastal

processes modeling prepared to inform the assessment of impacts (see Appendix C) it is concluded

that there will be no impacts potentially affecting the coastal processes with regard to sediment

transport within the study area or within Dublin Bay as a whole that would have the potential to

adversely affect the favourable conservation condition of these habitats.


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3.3.2 Potential effects on the Conservation Objectives of the South Dublin Bay cSAC

The Conservation Objectives (NPWS, 2013) for this cSAC site are to maintain or restore the favourable

conservation condition of Mudflats and sandflats not covered by seawater at low tide in South Dublin

Bay cSAC, which is defined by the following list of attributes and targets:

Habitat area: The permanent habitat area (720ha) is stable or increasing, subject to natural

processes.

Community extent: Maintain the extent of the Zostera-dominated community, subject to natural

processes.

Community structure (Zostera density): Conserve the high quality of the Zostera-dominated

community, subject to natural processes.

Community distribution: Conserve the „Fine sands with Angulus tenuis community complex‟ in a

natural condition.

Potential impacts identified in the current assessment with regard to the conservation objectives of this

site have been evaluated taking account of the proposed works and the coastal processes modeling

prepared to inform the assessment of impacts (see Appendix C). It is concluded that there will be no

impacts potentially affecting the coastal processes with regard to sediment transport within the study

area or within Dublin Bay as a whole that would have the potential to adversely affect the favourable

conservation condition of this habitat with regard to the habitat area and also with regard to the structure

and condition of the biological community complexes supported within this habitat area.

3.3.3 Potential effects on the Conservation Objectives of the Rockabill to Dalkey Island cSAC

The Conservation Objectives (NPWS, 2013) for this cSAC site are provided for the Annex I habitat and

Annex II species listed as qualifying interests. The conservation objectives for Annex I „Reef‟ habitat

within the cSAC are to maintain the favourable conservation condition of the habitat defined by the

following list of attributes and targets:

Habitat area: The permanent area (182ha) is stable or increasing, subject to natural processes.

Habitat distribution: Distribution is stable or increasing, subject to natural processes.

Community structure: Conserve the „Intertidal reef community complex‟ and „Subtidal reef

community complex‟ in a natural condition.

Taking account of the findings of the appraisal set out in this NIS, with reference to the specialist

surveys and reporting that was prepared to inform the EIS prepared in respect of the proposed

development, it is considered that there will be no direct impacts affecting reef habitat within the cSAC

arising from the proposed works. The modelling output from the coastal processes impact assessment

undertaken for the EIS has been included in the appraisal set out in the NIS (Appendix C). Potential


D01 53 Rev F01

impacts affecting reef habitat are identified with particular regard to siltation and smothering effects;

however, from the coastal processes modelling, it is demonstrated that there will be no indirect impacts

affecting reef habitat that would have the potential to adversely affect the conservation condition of the

habitat area, distribution or community structure with regard to the natural condition of the benthic

community complexes within this habitat.

The conservation objectives set out by the NPWS (2013) for harbour porpoise are to maintain the

favourable conservation condition of Harbour porpoise in Rockabill to Dalkey Island cSAC, which is

defined by the following list of attributes and targets:

Access to suitable habitat: Species range within the site should not be restricted by artificial

barriers to site use.

Disturbance: Level of impact Human activities should occur at levels that do not adversely affect

the harbour porpoise community at the site.

Specific technical clarification is provided in the NPWS supporting documentation for these

conservation objectives (NPWS, 2013) with reference to Appropriate Assessment. It is noted that

„artificial barriers‟ are identified as permanent features; as distinct from short-term or temporary

restrictions of access or range (NPWS, 2013). With reference to disturbance in the context of

Appropriate Assessment, man-made energy, including noise impacts must not result in a significant

negative impact on individuals and/or the community within the site; additionally operations / proposals

should not cause death or injury to individuals to an extent that may ultimately affect the harbour

porpoise community at the site.

Following this guidance, it is considered that the development proposed in the ABR Project, including

the capital dredging and spoil disposal works would have the potential to affect harbour porpoise

directly and indirectly within the cSAC site. Mitigation measures are required for the avoidance and

amelioration of impacts.

3.3.4 Potential effects on the Conservation Objectives of the North Bull Island SPA

The Conservation Objectives for the North Bull Island SPA (NPWS, 2011) are to maintain or restore the

favourable conservation condition of the bird species listed as Special Conservation Interests for this

SPA:

[wintering] Light-bellied Brent goose (Branta bernicla hrota)

[wintering] Shelduck (Tadorna tadorna)

[wintering] Teal (Anas crecca)

[wintering] Pintail (Anas acuta)

[wintering] Shoveler (Anas clypeata)


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[wintering] Oystercatcher (Haematopus ostralegus)

[wintering] Golden plover (Pluvialis apricaria)

[wintering] Grey plover (Pluvialis squatarola)

[wintering] Knot (Calidris canutus)

[wintering] Sanderling (Calidris alba)

[wintering] Dunlin (Calidris alpina)

[wintering] Black-tailed godwit (Limosa limosa)

[wintering] Bar-tailed godwit (Limosa lapponica)

[wintering] Curlew (Numenius arquata)

[wintering] Redshank (Tringa totanus)

[wintering] Turnstone (Arenaria interpres)

[wintering] Black-headed gull (Larus ridibundus)

Waterbirds & wetlands

From an assessment of the potential for pathways for impacts, taking account of the ecology and

distribution of the species listed as special conservation interests of this site, it is considered that only

the Light-bellied brent goose would have the potential to be directly affected by the proposed

redevelopment works and capital dredging scheme (Nairn, 2014); where the remaining species do not

occur or occur infrequently within the works area (Nairn, 2014).

Taking account of the coastal processes modelling prepared (Appendix C) it is concluded that the

proposed development would not have the potential to affect the intertidal habitats within the North

Dublin Bay, with reference to the intertidal and upper shore habitats that support the bird species for

which the SPA is designated (Nairn, 2014).

3.3.5 Potential effects on the Conservation Objectives of the South Dublin Bay & Tolka Estuary SPA

The Conservation Objectives for the South Dublin Bay & River Tolka Estuary SPA (NPWS, 2011) are to

maintain or restore the favourable conservation condition of the bird species listed as Special

Conservation Interests for this SPA:

[wintering] Light-bellied Brent goose (Branta bernicla hrota)

[wintering] Oystercatcher (Haematopus ostralegus)

[wintering] Ringed plover (Charadrius hiaticula)

[wintering] Grey plover (Pluvialis squatarola)

[wintering] Knot (Calidris canutus)

[wintering] Sanderling (Calidris alba)

[wintering] Dunlin (Calidris alpina)

[wintering] Bar-tailed godwit (Limosa lapponica)


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[wintering] Redshank (Tringa totanus)

[wintering] Black-headed gull (Croicocephalus ridibundus)

[passage] Roseate tern (Sterna dougallii)

[breeding & passage] Common tern (Sterna hirundo)

[passage] Arctic tern (Sterna paradisaea)

Wetlands

From an assessment of the potential for pathways for impacts, taking account of the ecology and

distribution of the species listed as special conservation interests of this site, it is considered that only

the Light-bellied brent goose would have the potential to be directly affected by the proposed

redevelopment works and capital dredging scheme (Nairn, 2014); where the remaining species do not

occur or occur infrequently within the works area (Nairn, 2014). Although Tern species do occur within

the Dublin Port area, at a distance from the proposed development works and would not be affected by

any increased disturbance (Nairn, 2014); furthermore, as the proposed dredging and disposal works are

proposed to be undertaken in the winter months, there would be no impacts on the feeding habitat and

prey species supporting these species during their summer breeding and late summer / early autumn

passage.

Taking account of the coastal processes modelling prepared (Appendix C) it is concluded that the

proposed development would not have the potential to affect the intertidal habitats within the North

Dublin Bay, with reference to the intertidal and upper shore habitats that support the bird species for

which the SPA is designated (Nairn, 2014).

3.4 MITIGATION MEASURES FOR THE PROTECTION OF NATURA 2000 SITES

3.4.1 Mitigation measures for the North Dublin Bay cSAC

The design stage mitigations proposed to avoid impacts affecting the coastal processes within Dublin

Bay, specifically in relation to the sediment budget, will effectively result in an avoidance of any impacts

which would have the potential to adversely affect the intertidal and coastal habitats listed as qualifying

interests of this cSAC.

In order to effectively reduce the potential for direct impacts resulting in habitat loss, no development,

including the storage of machinery or ancillary works should be carried out within this cSAC.

There are no further mitigation measures identified from the current assessment with regard to the

protection of the qualifying interests or their conservation objectives.


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3.4.2 Mitigation measures for the South Dublin Bay cSAC

The design stage mitigations proposed to avoid impacts affecting the coastal processes within Dublin

Bay, specifically in relation to the sediment budget, will effectively result in an avoidance of any impacts

which would have the potential to adversely affect the intertidal habitat listed as a qualifying interest of

this cSAC.

In order to effectively reduce the potential for direct impacts resulting in habitat loss, no development,

including the storage of machinery or ancillary works should be carried out within this cSAC .

There are no further mitigation measures identified from the current assessment with regard to the

protection of the qualifying interest and conservation objectives.

3.4.3 Mitigation measures for the Rockabill to Dalkey Island cSAC

From the findings of the coastal process and hydrodynamic modelling prepared to inform the EIS , it is

concluded that there will not be any significant impacts potentially affecting the Annex I Reef habitats

designated as qualifying interests of this cSAC. There are therefore no mitigation measures required for

the avoidance or reduction of impacts in this regard.

The proposed works will occur at all stages of the tide, and there is an increased likelihood of marine

mammals using the harbour at the high tide stage. It is best practice to employ a marine mammal

observer to ensure impacts of coastal works (including piling, demolition, dredging and dumping) are

minimised. Given the proposed works will take place in the vicinity of a candidate Special Area of

Conservation for harbour porpoise, the zone of behavioural responses to noise from piling operations is

likely to extend into the cSAC. Given the uncertainty in assessing the type and significance of

behavioural responses, and the duration of piling works, it is appropriate to employ a precautionary

approach with regards to impacts on populations within the cSAC. Assessing and monitoring of the

responses of harbour porpoise to noise, particularly within the cSAC, during construction is

recommended. Following guidelines from the regulatory authorities, the National Parks & Wildlife

Service (2013), the following precautionary measures are therefore advised to minimise the risk of

direct injury to marine mammals in the area of operations:

A trained and experienced Marine Mammal Observer (MMO)1 should be put in place during piling,

dredging, dumping, and demolition operations. The MMO will scan the surrounding area to ensure

1 A qualified marine mammal observer (MMO) is a visual observer who has undergone formal marine mammal

observation training (JNCC MMO training course or equivalent) and has a minimum of 6 weeks marine mammal survey experience at sea over a three year period. MMOs for use in Ireland should have field experience in marine mammal monitoring in European waters and be familiar with the Irish regulatory procedures relevant to the activity to which they are assigned, in order to ensure compliance. MMOs should have at least three years’


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no marine mammals are in a pre-determined exclusion zone in the 30-minute period prior to

operations. It is suggested that this exclusion zone is 500m for demolition and dredging activities,

and 1000m for piling activities considering the potential risks outlined.

Noise-producing activities shall only commence in daylight hours where effective visual monitoring,

as performed and determined by the MMO, has been achieved. Where effective visual monitoring is

not possible, the sound-producing activities shall be postponed until effective visual monitoring is

possible. Visual mitigation for marine mammals (in particular harbour porpoise) will only be effective

during daylight hours and if the sea state is 2-3 (Beaufort scale) or less..

For piling activities, where the output peak sound pressure level (in water) exceeds 170dB, a ramp-

up procedure must be employed following the pre-start monitoring. Underwater acoustic energy

output shall commence from a lower energy start-up and thereafter be allowed to gradually build up

to the necessary maximum output over a period of 20-40 minutes.

o Once operations have begun, operations should cease temporarily if a cetacean or seal is

observed swimming in the immediate (<50m) area of piling and dredging and work can be

resumed once the animal(s) have moved away.

o Dumping of material at sea should not take place if a cetacean or seal is within 50m of the

vessel.

o Any approach by marine mammals into the immediate (<50 m) works area should be

reported to the National Parks and Wildlife Service.

If there is a break in piling activity for a period greater than 30 minutes then all pre-activity

monitoring measures and ramp-up (where this is possible) should recommence as for start-up.

Once normal operations commence (including appropriate ramp-up procedures), there is no

requirement to halt or discontinue the activity at night-time, nor if weather or visibility conditions

deteriorate, nor if marine mammals occur within a radial distance of the sound source that is

500m for dredging and demolition works, and 1000m for piling activities.

o The MMO will keep a record of the monitoring using a „MMO form location and effort

(coastal works)‟ available from the National Parks & Wildlife Service (NPWS) and

submit to the NPWS on completion of the works, as described in the NPWS guidance

(2014).

In order to reliably quantify the zone of responsiveness associated with the proposed

programme of piling activities associated with the Alexandra Basin Redevelopment, one of the

following methods will be used:

experience in surveying/identifying harbour porpoise as the area is important for this species and they are difficult to visually detect even in a favourable sea-state.


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o Modelling of sound propagation calibrated using field measurements; or

o Deployment of hydrophones in combination with passive acoustic monitoring.

3.4.4 Mitigation measures for the North Bull Island SPA

The Brent Geese that regularly use Alexandra Basin West in winter have adapted to feeding on spilt

agricultural products. Redevelopment of the quays and jetties in the Basin will be carried out on a

phased basis so that shipping can continue to use parts of the Basin at all times. As agricultural

products will continue to be unloaded here, albeit in different locations, the geese will continue to be

attracted to the spillages. According to Nairn (2014) no other mitigation measures in relation to avifauna

are required with regard to the avoidance of effects on the SPA.

3.4.5 Mitigation measures for the South Dublin Bay & Tolka Estuary SPA

The Brent Geese that regularly use Alexandra Basin West in winter have adapted to feeding on spilt

agricultural products. Redevelopment of the quays and jetties in the Basin will be carried out on a

phased basis so that shipping can continue to use parts of the Basin at all times. As agricultural

products will continue to be unloaded here, albeit in different locations, the geese will continue to be

attracted to the spillages. According to Nairn (2014) no other mitigation measures in relation to avifauna

are required with regard to the avoidance of effects on the SPA.

3.5 ASSESSMENT OF IN COMBINATION EFFECTS WITH OTHER PLANS OR PROJECTS

Article 6(3) of the Habitats Directive requires that in combination effects of the project with other plans

or projects are considered. As part of the Dublin Port Masterplan‟s Strategic Natura Impact Statement

(SNIS) all relevant plans and projects were assessed for their potential to have in-combination effects

with the Dublin Port Masterplan and its various elements. Preliminary screening at that time indicated

that ten projects or plans were assessed as having possible significant impacts, whilst eight projects or

plans were assessed as having no impact. Many of the plans and planning related reports assessed as

part of the Masterplan Strategic NIS indicated that EIA‟s and/or Appropriate Assessments would be

required once individual projects were finalised.

At a project level, the individual projects either identified no impacts on Natura 2000 sites or proposed

mitigation to ensure that no impacts would take place. Licence arrangements were required to be put in

place for some aspects of mitigation or project activities to be carried forward.


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The key projects identified as having the potential for in combination effects with the ABR is the

„Dollymount Promenade and Flood Protection Project‟; a component of the „S2S Sutton to Sandycove

Project‟ and the „Dublin Eastern Bypass‟. The assessment of in combination effects within the

Masterplan identified the S2S project to have a number of potential impacts to the North Bull Island SPA

and the South Dublin Bay & River Tolka Estuary SPA. The NIS for the S2S Project proposed a number

of mitigation measures in relation to the proposed scheme and has concluded, on the basis of effective

implementation of those measures, that there will be no impact on the integrity of the Natura 2000 sites.

Since the publication of the Masterplan, a Part 8 planning process has been initiated by Dublin City

Council in relation to the S2S Cycleway and Footway interim works between Bull Road (Wooden

Bridge) and Causeway Road. This is an interim scheme comprising elements of two separate projects,

the Dollymount Promenade & Flood Protection Project (DPFPP) and the North City Arterial Watermain

(NCAM), both of which have planning approval from An Bord Pleanála. Both projects were also

separately assessed in terms of the requirements of the Habitats Directive and were concluded to have

no significant effects on the Natura 2000 Sites and, ultimately, as having no adverse effect on the

integrity of any of Natura 2000 sites. As the above interim project elements were concluded to have no

adverse effects on the integrity of any of the Natura 2000 sites, they have not considered further under

this appraisal for cumulative and in-combination effects with the ABR Project.

The assessment of in-combination effects within the Masterplan and the Dublin Eastern Bypass

identified possible effects on the South Dublin Bay cSAC and the South Dublin Bay and River Tolka

Estuary SPA. The Dublin Eastern Bypass (DEB) concept is a possible future urban motorway to

connect the existing Dublin Port Tunnel to the M50 in the Sandyford area to achieve an orbital road

network around Dublin. Previously suggested alignments for the DEB route have intersected with the

Dublin Port area. Therefore, in preparing the Alexandra Basin Redevelopment (ABR) application, DPC

has consulted with the relevant stakeholders, including the National Roads Authority (NRA) and the

Dublin City Council (DCC). To summarise from a review of the various adopted and draft policies and

planning documents which support the principle of the DEB, there are no formally adopted route

protection corridors and the scheme has been recommended for deferral until 2030. Since the feasibility

and corridor protection studies were issued in 2007 and 2009, only one planning document includes an

indicative diagrammatical reference to one DEB corridor option. The planning documents confirm that a

statutory process is required to progress the indicative routes, including Environmental Impact

Assessment (EIA), economic assessment and public consultation process. In May 2011, and again in

December 2013, the NRA stated that they forwarded the feasibility report to the Minister for Transport in

November 2007 for Government consideration and decision, and the NRA is still awaiting further

direction on the matter. Given the fact that no detailed designs or exact locations have been chosen it is

therefore not possible this stage in the ABR Project to assess the likelihood of potential in combination

effects. Should the DEB commence or progress over the coming years and therefore the likelihood of

potential in combination effects arise, the NRA will need to consider the information set out in the ABR

EIS and this NIS, bearing in mind the entire project could take a number of years to complete


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throughout various stages. This is in line with the Regional Planning Guidelines for the Greater Dublin

Area 2010-2022 Dublin Regional Authority (DRA, 2010) which identified;

the concept of an Eastern Bypass which has the potential to impact on Natura 2000 sites in

Dublin Bay whereby a Natura Impact Statement (NIS) will need to accompany future route

selection examination

Any Dublin Port extension which has the potential to impact on Natura 2000 sites in Dublin Bay

will need to be accompanied by an appropriate NIS.

Dublin Port Maintenance Dredging

DPC currently has a maintenance dredging programme in place for which Dumping at Sea (DaS)

Permit No. S0004-01 was issued by the Environmental Protection Agency on 28th July 2011. The permit

runs to 2016.Any application to renew the maintenance dredging permit would require the competent

authority (in this instance, the EPA) to undertake an Appropriate Assessment pursuant to the

requirements of the Habitats Directive, following the submission of an NIS by DPC, to ensure that there

are no adverse effects effects on the integrity of the surrounding Natura 2000 sites and, in particular,

the Rockabill to Dalkey cSAC.

Dublin Array (An Offshore Windfarm on the Kish and Bray Banks)

The Dublin Array project is an offshore wind farm that is being developed on the Kish and Bray Banks in

the Irish Sea, 10km off the coast of Dublin and Wicklow. As part of the planning application a Natura

Impact Statement was completed (Ecofact, 2013) http://www.dublinarray.com/downloads/2nis/Natura-

Impact-Statement.pdf for which the cSAC sites within the study area of the proposed wind energy

development were assessed with particular regards to potential impacts affecting marine mammals; i.e.

Grey seals and Harbour porpoises, Annex II species listed as qualifying interests of two cSAC sites

within the study area. From the conclusions of the Marine Mammals assessment (BEC, 2013) carried

out as part of the Dublin Array project, it was evaluated that the development will not have a significant

adverse effect on the associated Natura 2000 sites; with the implementation of prescribed mitigation

measures. The mitigation measures proposed will avoid direct injury to marine mammals during

construction, however, a temporary reduction in Harbour porpoise activity was identified within the

proposed Rockabill to Dalkey Island cSAC during piling operations; this is anticipated to reduce to nil

while construction is on-going at the southern end of the Array. The temporary and reversible nature of

this effect will not prevent Natura 2000 sites from achieving their Conservation Objectives or result in

significant adverse effects on the integrity of the site. When considered in-combination with the ABR

Project and in particular the dumping at sea element of the dredging works the impacts to Harbour

porpoise must be considered. Accordingly, the following points need to be taken into consideration;

http://www.dublinarray.com/downloads/2nis/Natura-Impact-Statement.pdf

http://www.dublinarray.com/downloads/2nis/Natura-Impact-Statement.pdf


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According to the Dublin Array Project Timelines, commissioning and construction works will not

commence until 2018, therefore, it is likely that the ABR Project‟s capital dredging will already

have commenced and also may overlap, given the anticipated duration at present of 6 years.

The precautionary and preventative measures for Harbour porpoise outlined in Section 3.4.3 include Marine Mammal Observers and (in the absence of a predictive sound propagation

model) a dedicated sound propagation modelling approach, as it is not possible to accurately

predict the likely impact of sound on marine mammals within the cSAC from the proposed piling

operations in Alexandra Basin West or at the Berths 52/53 Basin. Field measurements of

underwater sound in the cSAC will determine the attenuation rates under various tidal

conditions and the noise levels encountered by marine mammals, particularly within the cSAC

area. This will enable confirmation of the predicted received sound levels from construction

activity within the cSAC.

The completion of the early elements (Piling, demolition, construction and some dredging

elements between 2014 - 2018) of the ABR Project prior to the commencement of the Dublin

Array project in 2018, coupled with the preventative and confirmatory mitigation measures

identified in this NIS will ensure no permanent or significant effects on the integrity of the

Rockabill to Dalkey cSAC and its qualifying feature of harbour porpoise.

3.6 RESIDUAL EFFECTS ON THE CONSERVATION OBJECTIVES OF NATURA 2000 SITES

3.6.1 Conservation objectives of the North Dublin Bay cSAC

The current assessment has determined that there would be no potential for adverse effects on the

coastal and terrestrial habitats and Annex II species listed as qualifying interests of this cSAC, arising

from the proposal. Potential effects on the Conservation Objectives of this site are therefore limited to

effects on the following intertidal habitats listed as qualifying interests:


[1310] Salicornia and other annuals colonizing mud and sand

[1330] Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

[1410] Mediterranean salt meadows (Juncetalia maritimi)

An overview of the potential for adverse effects, mitigation measures proposed and the residual impacts

with regard to this cSAC are presented in Table 3.3.Taking account of the findings of the coastal

processes modelling undertaken to inform the EIS prepared for the planning application , it is

considered that there is no potential for residual effects on the maintenance of the above habitats, as

per the conservation objectives of this site (NPWS, 2011). In these circumstances, the proposed

development will not adversely affect the integrity of the North Dublin Bay cSAC, in view of the site‟s

conservation objectives.


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3.6.2 Conservation objectives of the South Dublin Bay cSAC

The current assessment has determined that any potential adverse effects on the intertidal Annex I

habitat listed as a qualifying interest of the cSAC would be limited to impacts arising due to indirect

effects of sediment transport and coastal processes. The key qualifying interest of this site is:



with regard to this cSAC are presented in Table 3.3. Taking account of the findings of the coastal

processes modelling undertaken to inform the EIS prepared for the planning application (RPS, 2014), it

is considered that there is no potential for residual effects on the maintenance of the above habitat, as

per the conservation objectives of this site (NPWS, 2013). This is considered, where the proposal will

not result in any direct effects on the habitat and benthic communities, neither will there be a significant

impact on the biological communities arising from indirect impacts such as sedimentation, as

demonstrated by the coastal processes modelling (see Appendix C). In conclusion, the proposed

development will not adversely affect the integrity of the South Dublin Bay cSAC, in view of the site‟s

conservation objectives.

3.6.3 Conservation objectives of the Rockabill to Dalkey Island cSAC

The current assessment takes account of the output of the coastal processes modelling prepared to

inform the EIS for the proposal (RPS, 2014). Relevant modelling figures are presented in Appendix C

and demonstrate, as was concluded in the benthic ecology chapter of the EIS (Chapter 5; RPS, 2014),

that there will be no direct or indirect impacts affecting reef habitat within the cSAC. This is evaluated

specifically with regard to the potential for siltation effects and impacts affecting the conservation

objectives (NPWS, 2013); with regard to the community structure and condition of the benthic epifaunal

community complex within this habitat.

According to the assessment prepared by Cronin and Jessopp (2014) the residual impacts of the

proposed works affecting marine mammals will not be significant. Potential direct impacts from the

noise from the proposed construction activities on marine mammals will be insignificant once the

mitigation measures included in this assessment are implemented. The changes to benthos in the dump

area will have potential impacts on prey availability to marine mammals in the area but as it is not a

critical foraging area for marine mammals; any effects will be negligible on both the population as well

as the individual level. Behavioural responses to noise from dredging and construction are considered

to be temporary and limited to the duration of the works, and will be reduced for the duration of the

works once the proposed mitigation measures are put in place (Cronin and Jessopp, 2014). With full

implementation of the mitigation measures outlined in section 3.4.3, there will be no significant impacts

of the proposed development on mammal mammals, including harbour porpoise. It is concluded that


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there will be no significant impacts of the proposed development on the Conservation Objectives of the

Rockabill to Dalkey Island cSAC.


with regard to the conservation objectives of this cSAC are presented in Table 3.3.

Article 6(3) of the Habitats Directive must be interpreted as meaning that a plan or project not directly

connected with or necessary to the management of a site will adversely affect the integrity of that site if

it is liable to prevent the lasting preservation of the constitutive characteristics of the site that are

connected to the presence of a priority natural habitat whose conservation was the objective justifying

the designation of the site. In circumstances where the ABR project will not prevent the lasting

preservation of reefs or the harbour porpoise, which are the constitutive characteristics of the site, the

proposed development will not adversely affect the integrity of the Rockabill to Dalkey Island cSAC,

having regard to its conservation objectives.

3.6.4 Conservation objectives of the North Bull Island SPA

According to Nairn (2014) there will be no significant impacts of the proposed development on either

breeding birds or wintering birds within the Port or the Liffey Channel or in the approved dredge

disposal site, with the implementation of the recommended mitigation measures. It is concluded that


Special Protection Area, with regard to the maintenance (or restoration) of the conservation condition of

the bird species listed as special conservation interests. An overview of the potential for adverse effects,

mitigation measures proposed and the residual impacts with regard to this SPA are presented in Table 3.3. The proposed development will not adversely affect the integrity of the North Bull Island SPA, in

view of the site‟s conservation objectives.

3.6.5 Conservation objectives of the South Dublin Bay & Tolka Estuary SPA

According to Nairn (2014) there will be no significant impacts of the proposed development on either

breeding birds or wintering birds within the Port or the Liffey Channel or in the approved dredge

disposal site, with the implementation of the recommended mitigation measures. It is concluded that


Special Protection Area, with regard to the maintenance (or restoration) of the conservation condition of

the bird species listed as special conservation interests. An overview of the potential for adverse effects,

mitigation measures proposed and the residual impacts with regard to this SPA are presented in Table 3.3. In these circumstances, the proposed development will not adversely affect the integrity of the

South Dublin Bay & Tolka Estuary SPA, in view of the site‟s conservation objectives.


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Table 3.3 Summary of the potential impacts, mitigation and residual impacts identified for the Natura 2000 designations within the zone of influence of the proposed Alexandra Basin Redevelopment and associated capital dredging.

Site Name Qualifying Interests Potential Impacts Potential Cumulative

Impacts Proposed Mitigation Residual Impacts

Candidate Special Areas of Conservation (cSACs)

North Dublin Bay cSAC

Mudflats and sandflats not covered by seawater at low tide; Annual vegetation of drift lines; Salicornia and other annuals colonizing mud and sand; Atlantic salt meadows (Glauco-Puccinellietalia maritimae); Mediterranean salt meadows (Juncetalia maritimi); Embryonic shifting dunes; Shifting dunes along the shoreline with Ammophila arenaria ("white dunes"); * Fixed coastal dunes with herbaceous vegetation ("grey dunes"); Humid dune slacks Petalophyllum ralfsii

The proposed redevelopment, including both the construction and operation phase, in addition to the associated capital dredging scheme are not located within this cSAC designation, precluding any direct impacts. Indirect impacts may potentially arise with regard to alteration of coastal processes and water quality impacts affecting the intertidal habitats within the cSAC. These effects are principally associated with the dredging and development of the shipping channel.

Potential cumulative impacts are limited to those that would have the potential to affect the intertidal mudflat and sandflat habitats and saltmarsh habitats within the cSAC. There is no potential for interactions with the remaining Annex I habitats and Annex II species listed as qualifying interests of this site.

Taking account of design stage mitigation with regard to avoidance of direct impacts, as well as indirect water quality impacts, it is considered that no further mitigation for the protection of the Annex I habitats and Annex II species within this cSAC are required.

From the results of the coastal processes modelling included in Appendix C of this report, it is concluded that there will be no impacts arising from the proposal that would affect the sediment transport regime or sediment budget within Dublin Bay, upon which the intertidal Annex I habitats depend. There are therefore no significant impacts identified that would have the potential to give rise to adverse effects on the integrity of this designated site.

South Dublin Bay cSAC

Mudflats and sandflats not covered by seawater at low tide

The proposed redevelopment, including both the construction and operation phase, in addition to the associated capital dredging scheme are not located within this cSAC designation, precluding any direct impacts. Indirect impacts may potentially arise with regard to alteration of coastal processes and water quality impacts affecting the intertidal habitat within the cSAC. These effects are principally associated with the dredging and development of the shipping channel.

Potential cumulative impacts are limited to those that would have the potential to affect the intertidal mudflat and sandflat within the ccSAC.

Taking account of design stage mitigation with regard to avoidance of direct impacts, as well as indirect water quality impacts, it is considered that no further mitigation for the protection of the Annex I habitat within this cSAC are required.

From the results of the coastal processes modelling included in Appendix C of this report, it is concluded that there will be no impacts arising from the proposal that would affect the sediment transport regime or sediment budget within Dublin Bay, upon which this intertidal Annex I habitat depends. There are therefore no significant impacts identified that would have the potential to give rise to adverse effects on the integrity of this designated area.


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Site Name Qualifying Interests Potential Impacts Potential Cumulative Impacts

Proposed Mitigation Residual Impacts


Reefs Harbour porpoise

The proposed redevelopment of Alexandra Basin does not require works within this cSAC; however, the eastern extremity of the required dredging within the shipping channel and the dredge spoil disposal site are within the cSAC boundary. The Annex I reef habitat does not occur within this works area; however the harbour porpoise, a highly mobile species may potentially occur on occasion giving rise to the potential for direct effects. Indirect impacts are identified with regard to the generation of underwater noise and turbidity arising during the piling, dredging and dumping operations which may potentially affect harbour porpoise at a distance, within the cSAC. Reef habitat may also be indirectly affected arising from the dispersal of silt from the dredging and dumping activities which would have a smothering effect on benthic epifaunal communities.

Potential cumulative impacts are identified with regard to existing ongoing background noise impacts associated with shipping and near shore developments within the Dublin Bay area which may cumulatively affect harbour porpoise. There are no impacts affecting reef habitat arising from the current proposal which would have the potential to give rise to in-combination or cumulative effects.

Taking account of the mobility of harbour porpoise populations within the Dublin Bay area, specific mitigation measures are proposed for the avoidance of significant impacts within and outside of the cSAC boundary. Noise reduction measures and monitoring of activity and aversive behaviour are proposed as key mitigation. There are no mitigation measures proposed for reef habitat in the absence of the potential for significant impacts.

From the results of the coastal processes modelling included in Appendix C of this report, it is concluded that there will be no impacts arising from the proposal that would affect the Annex I reef habitat within this designation. With full implementation of the mitigation measures outlined in section 3.4.3, there will be no significant impacts of the proposed development on mammal mammals, including harbour porpoise. It is concluded that there will be no significant impacts of the proposed development on the Conservation Objectives of the Special Areas Conservation in Dublin Bay or neighbouring coastlines, including the Rockabill to Dalkey Island cSAC.

Special Protection Areas (SPAs)


Wintering species: Light-bellied Brent goose; Shelduck; Teal; Pintail; Shoveler; Oystercatcher; Golden plover; Grey plover; Knot; Sanderling; Dunlin; Black-tailed godwit; Bar-tailed godwit; Curlew; Redshank; Turnstone; Black-headed gull

The proposed redevelopment, including both the construction and operation phase, in addition to the associated capital dredging scheme do not require works within this SPA designation, precluding any direct impacts. Indirect impacts are identified with regard to the presence of Light-bellied brent geese feeding on spilt grain

Potential cumulative impacts are limited to those that would have the potential to give rise to disturbance impacts affecting the wintering bird species or alterations to the intertidal habitats within the SPA, which support these

The wintering geese feeding within the port are evaluated as being habituated to disturbance and as grain shipments will continue, no further mitigation is required (Nairn, 2014). Taking account of

From the results of the coastal processes modelling included in Appendix C of this report, it is concluded that there will be no impacts arising from the proposal that would affect the sediment transport regime or sediment budget within Dublin Bay, which maintains the structure and function of the intertidal feeding grounds supporting these


D01 66 Rev F01

Site Name Qualifying Interests Potential Impacts Potential Cumulative Impacts

Proposed Mitigation Residual Impacts

Waterbirds & wetlands within Dublin Port which would be subject to disturbance during the works. Additional impacts may potentially arise with regard to alteration of coastal processes and water quality impacts affecting the intertidal habitats supporting wintering birds within the SPA. These effects are principally associated with the dredging and development of the shipping channel.

wintering bird species. design stage mitigation with regard to avoidance of direct impacts, as well as indirect water quality impacts, it is considered that no further mitigation for the protection of the intertidal habitats within this SPA are required.

wintering birds. There are therefore no significant impacts identified that would have the potential to give rise to adverse effects on the integrity of this designated area.

South Dublin Bay and Tolka Estuary SPA

Wintering species: Light-bellied Brent goose; Oystercatcher; Ringed plover; Grey plover; Knot; Sanderling; Dunlin; Bar-tailed godwit; Redshank; Black-headed gull Passage species: Roseate tern; Common tern (incl. breeding); Arctic tern Wetlands & waterbirds

The proposed redevelopment, including both the construction and operation phase, in addition to the associated capital dredging scheme do not require works within this SPA designation, precluding any direct impacts. Indirect impacts are identified with regard to the presence of Light-bellied brent geese feeding on spilt grain within Dublin Port which would be subject to disturbance during the works. Additional impacts may potentially arise with regard to alteration of coastal processes and water quality impacts affecting the intertidal habitats supporting wintering birds within the SPA. These effects are principally associated with the dredging and development of the shipping channel. The proposed dredging and spoil disposal works will be limited to the winter months and will therefore not overlap with the passage and breeding seasons for the tern species listed as special conservation interests of this site.

Potential cumulative impacts are limited to those that would have the potential to give rise to disturbance impacts affecting the wintering bird species or alterations to the intertidal habitats within the SPA, which support these wintering bird species.

The wintering geese feeding within the port are evaluated as being habituated to disturbance and as grain shipments will continue, no further mitigation is required (Nairn, 2014). Taking account of design stage mitigation with regard to avoidance of direct impacts, as well as indirect water quality impacts, it is considered that no further mitigation for the protection of the intertidal habitats within this SPA are required.

From the results of the coastal processes modelling included in Appendix C of this report, it is concluded that there will be no impacts arising from the proposal that would affect the sediment transport regime or sediment budget within Dublin Bay, which maintains the structure and function of the intertidal feeding grounds supporting these wintering birds. As the populations of breeding and passage terns are located at a distance from the proposed development works and will be absent from the SPA during the proposed dredging works (limited to winter months) there will be no residual impacts on these species (Nairn, 2014). There are therefore no significant impacts identified that would have the potential to give rise to adverse effects on the integrity of this designated area.

Alexandra Basin Redevelopment Natura Impact Statement

D01 67 Rev F01

4 NIS CONCLUSION

This Natura Impact Statement has considered the potential for significant impacts arising from the

proposed Alexandra Basin Redevelopment and associated capital dredging scheme that would have

the potential to adversely affect any Natura 2000 site; with regard to their qualifying interests and

conservation objectives. The proposed redevelopment within the Alexandra Basin does not lie within

any Natura 2000 designation; however, it is in close proximity to the following sites:




South Dublin Bay & Tolka Estuary SPA.

In addition, the associated capital dredging scheme and disposal of dredged material at the disposal

site will require works within and adjacent to the Rockabill to Dalkey Island cSAC.

The potential for direct, indirect and cumulative impacts affecting the above designations has therefore

been assessed in this NIS. The appraisal undertaken in this NIS has been informed by project-specific

site investigations and specialist reporting with reference to the ecological communities and habitats

potentially affected by the proposed development, in order to provide a scientific basis for evaluations.

Measures for impact reduction have been incorporated into the project proposal, including design-stage

avoidance, in addition to mitigation measures proposed in the NIS for the avoidance and reduction of

impacts on the qualifying interests and conservation objectives of the designated Natura 2000 sites

within the study area. With the implementation of these measures the ABR project will not result in

direct, indirect or cumulative impacts which would have the potential to adversely affect the qualifying

interests/special conservation interests of the Natura 2000 sites within the study area with regard to the

range, population densities or conservation status of the habitats and species for which these sites are

designated (i.e. conservation objectives).

The provisions of Article 6 of the „Habitats‟ Directive 92/43/EC (2000) defines „integrity‟ as the

„coherence of the site‟s ecological structure and function, across its whole area, or the habitats, complex

of habitats and / or population of species for which the site is or will be classified‟. Moreover, the CJEU

has held that Article 6(3) of the Habitats Directive must be interpreted as meaning that a plan or project

not directly connected with or necessary to the management of a site will adversely affect the integrity of

that site if it is liable to prevent the lasting preservation of the constitutive characteristics of the site that

are connected to the presence of a priority natural habitat whose conservation was the objective

justifying the designation of the site.


D01 68 Rev F01

In circumstances where the ABR project will not prevent the lasting preservation of any constitutive

characteristic of any designated site, the proposed development will not adversely affect the integrity of

any designated site, having regard to the conservation objectives of each site.

It is therefore concluded, beyond reasonable scientific doubt, that the proposed project with the

implementation of the prescribed mitigation measures will not give rise to significant impacts, either

individually or in combination with other plans and projects, in a manner which adversely affects the

integrity of any designated site within the Natura 2000 network.


D01 69 Rev F01

5 REFERENCES

Council Directive 79/409 EEC on the Conservation of Wild Birds

Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora.

Department of the Environment, Heritage and Local Government (2009). Appropriate Assessment of

Plans and Projects in Ireland, Guide for Planning Authorities, Dublin.

Cronin, M. & Jessopp, M. (2014) Alexandra Basin Redvelopment: Marine Mammals Impact

Assessment. University College Cork (UCC).

European Commission (2000a) Communication from the Commission on the Precautionary Principle,

Office for Official Publications of the European Communities, Luxembourg.

European Commission (2000b) Managing Natura 2000 Sites: the provisions of Article 6 of the „Habitats‟

Directive 92/43/EEC, Office for Official Publications of the European Communities, Luxembourg.

European Commission (2001) Assessment of Plans and Projects Significantly Affecting Natura 2000

Sites: Methodological guidance on the provisions of Article 6(3) and (4) of the Habitats Directive

92/43/EEC, Office for Official Publications of the European Communities, Luxembourg.

European Commission (2008) Guidance document on Article 6(4) of the 'Habitats Directive' 92/43/EEC

– Clarification of the concepts of: alternative solutions, imperative reasons of overriding public interest,

compensatory measures, overall coherence, opinion of the commission, Office for Official Publications

of the European Communities, Luxembourg.

European Commission (2011) Guidelines on the Implementation of the Birds and Habitats Directives in

Estuaries and Coastal Zones, with particular attention to port development and dredging.

European Communities (Natural Habitats) Regulations (S.I. No. 477 of 2011)

Jacobs (2012) Dublin Port Masterplan – Strategic Environmental Assessment Environmental Report.

Jacobs Engineering Ireland Ltd.

Nairn, R. (2014) Alexandra Basin Redevelopment: Avifauna Impact Assessment Report. Natura

Consultants Ltd.

NPWS (2010) Appropriate Assessment of Plans and Projects in Ireland – Guidance for Planning

Authorities produced by the Department of the Environment, Heritage and Local Government (NPWS,

2010).


D01 70 Rev F01

NPWS (2011a) Conservation objectives for North Dublin Bay cSAC [000206]. Generic Version 3.0.

Department of Arts, Heritage & the Gaeltacht.

NPWS (2011b) Conservation objectives for North Bull Island SPA [004006]. Generic Version 4.0.

Department of Arts, Heritage & the Gaeltacht.

NPWS (2011c) Conservation objectives for South Dublin Bay and River Tolka Estuary SPA [004024].

Generic Version 4.0. Department of Arts, Heritage & the Gaeltacht.

NPWS (2013a) Conservation Objectives: South Dublin Bay cSAC 000210. Version 1. National Parks

and Wildlife Service, Department of Arts, Heritage and the Gaeltacht

NPWS (2013b) Conservation Objectives: Rockabill to Dalkey Island cSAC 003000. Version 1. National

Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.

NPWS (2014) Guidance to Manage the Risk to Marine Mammals from Man-made Sound Sources in

Irish Waters. Department of Arts, Heritage and the Gaeltacht.


Avian Impact Assessment

App

endi

x A

Dublin Port Company

ALEXANDRA BASIN REDEVELOPMENT

APPENDIX TO NATURA IMPACT STATEMENT

AVIAN IMPACT ASSESSMENT

February 2014

Prepared by

Natura Environmental Consultants Ltd

Alexandra Basin Redevelopment Project: Avian Impact Assessment to inform the NIS

Page 2 of 28 Rev#2 07/02/2014

TABLE OF CONTENTS

1 INTRODUCTION ............................................................................................. 4

1.1 GENERAL INTRODUCTION ................................................................................................. 4

1.2 STATEMENT OF COMPETENCY ........................................................................................... 4

2 METHODOLOGY ............................................................................................ 5

2.1 BIRD SURVEYS WITHIN THE PROPOSED DEVELOPMENT AREA .............................................. 5

2.1.1 Winter bird surveys ........................................................................................... 5

2.1.1.1 Brent Geese ................................................................................................................. 5

2.1.1.2 Winter Bird Surveys in the Tolka Estuary .................................................................... 5

2.1.2 Breeding bird surveys ....................................................................................... 6

2.1.2.1 Black Guillemots........................................................................................................... 6

2.1.2.2 Tern colonies ................................................................................................................ 6

2.1.3 Bird surveys within the shipping channel and dredge disposal site ................. 6

3 DESCRIPTION OF EXISTING ENVIRONMENT ............................................. 9

3.1 DESIGNATED AREAS ......................................................................................................... 9

3.2 BIRD POPULATIONS WITHIN DUBLIN PORT ........................................................................ 10

3.2.1 Wintering birds ................................................................................................ 10

3.2.1.1 Brent Geese ............................................................................................................... 10

3.2.1.2 Wintering birds in the Tolka Estuary .......................................................................... 11

3.2.2 Breeding birds ................................................................................................ 12

3.2.2.1 Black Guillemots......................................................................................................... 12

3.2.2.2 Breeding Terns ........................................................................................................... 13

3.2.2.3 Other bird species ...................................................................................................... 14

3.3 BIRD POPULATIONS IN THE SHIPPING CHANNEL ................................................................ 14

3.4 BIRD POPULATIONS AT THE APPROVED DREDGE DISPOSAL SITE ........................................ 15

4 LIKELY SIGNIFICANT IMPACTS ................................................................. 17

4.1 ALEXANDRA BASIN WEST REDEVELOPMENT .................................................................... 17

4.1.1 Description of proposed development ............................................................ 17

4.1.2 Impacts on birds ............................................................................................. 17

4.2 INFILL OF THE BERTHS 52/53 BASIN ............................................................................ 18



Page 3 of 28 Rev#2 07/02/2014

4.2.2 Impacts on birds ............................................................................................. 18

4.3 CAPITAL DREDGING OF THE APPROACH CHANNEL ............................................................ 18


4.3.2 Impacts on birds ............................................................................................. 19

4.3.2.1 Direct impacts of dredging ......................................................................................... 19

4.3.2.2 Indirect or long-term impacts of dredging .................................................................. 19

4.4 DISPOSAL OF DREDGED MATERIAL IN THE APPROVED DREDGE DISPOSAL SITE ................... 21

4.4.1 Description of the proposed development ...................................................... 21

4.4.2 Impacts on birds ............................................................................................. 21

4.5 OVERALL IMPACTS ON SPECIAL PROTECTION AREAS IN DUBLIN COASTAL AREA ................ 21

4.5.1 Alexandra Basin West Redevelopment .......................................................... 22

4.5.2 Capital dredging of Shipping Channel ............................................................ 23

4.5.3 Disposal of dredged material in the approved dredge disposal site .............. 24

5 MITIGATION MEASURES............................................................................. 25

5.1 ALEXANDRA BASIN REDEVELOPMENT AND INFILL OF BERTHS 52/53 ................................. 25

5.1.1 Brent Geese ................................................................................................... 25

5.1.2 Black Guillemots ............................................................................................. 25

6 CONCLUSIONS ............................................................................................ 26

7 REFERENCES .............................................................................................. 27


Page 4 of 28 Rev#2 07/02/2014

1 INTRODUCTION

1.1 GENERAL INTRODUCTION

This report provides an evaluation and assessment of impacts on birds in the Dublin Port area, in the navigational channel and in the approved dredge disposal site with regard to Dublin Port Company’s (DPC) proposed Alexandra Basin Redevelopment (ABR) Project and associated Capital Dredging Scheme. It also addresses any possible impacts on Special Protection Areas in the Dublin area that could have some connectivity with the proposed development. The ABR Project has four main components:

(1) Works within the Alexandra Basin (2) Infill of Berths 52/53 (3) Capital dredging of the Liffey Channel (4) Dumping of the dredged material in the approved dredge disposal site

1.2 STATEMENT OF COMPETENCY

The author of this report, Richard Nairn, BA (Mod) MA (Natural Sciences) CEnv FCIEEM MIBiol, is a Senior Environmental Scientist and Managing Director of Natura Environmental Consultants Ltd. He has a comprehensive knowledge of waterbird ecology and survey methodology. In the 1980s he was National Director of IWC (BirdWatch Ireland). Since 1990 he has specialised in Environmental Impact Assessment for a variety of developments including roads, pipelines, port developments, sewage treatment works and industrial developments. He has been commissioned to monitor birds in the area of Dublin Port since 2009 and currently represents DPC on the management group for the Dublin Bay Birds project, run by BirdWatch Ireland. He is also the lead ecologist advising Dublin City Council in relation to the proposed extension of Ringsend Wastewater Treatment Works in Dublin. He is author or editor of three books. He is a Chartered Environmentalist and Fellow of the Chartered Institute of Ecology and Environmental Management.


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2 METHODOLOGY

2.1 BIRD SURVEYS WITHIN THE PROPOSED DEVELOPMENT AREA

The habitats within Dublin Port are highly artificial. Nevertheless, they are used by a limited number of bird species in both winter and summer. A desk review was undertaken of all previous information on birds in the port area and a series of baseline surveys was carried out over the full year, January 2013 to January 2014. Additional surveys of wintering birds in the Tolka Estuary (between the Port and Clontarf) were carried out during the four winters up to, and including, 2012/13. During 2013/14, a series of boat-based surveys were also undertaken of seabirds in the navigation channel and approaches to the port. An additional winter survey of the approved dredge disposal site was undertaken. The methodologies for these surveys are outlined below.

2.1.1 Winter bird surveys

2.1.1.1 Brent Geese

The berths at Alexandra Basin West are used for the unloading of agricultural products and occasional spillage of these materials attracts flocks of Brent Geese to forage here. A series of surveys of Brent Geese was undertaken in Alexandra Basin West between January and April 2013 (12 surveys) and between October 2013 and January 2014 (5 surveys). These surveys were targeted on a wide range of tide heights and ranges and different times of day. Geese were counted using 10 x 50 binoculars and any ringed birds were recorded with their alphanumerical codes. All other bird species present in Alexandra Basin West were also recorded on these dates.

2.1.1.2 Winter Bird Surveys in the Tolka Estuary

A total of 27 monthly low tide surveys have been undertaken between the months of September and April, over four winters, covering all of the intertidal areas in the Tolka Estuary from Fairview to the Bull Wall. Due to adverse weather, no surveys were undertaken in September or November 2010 but an additional survey was carried out in April 2011. All waterbird species have been mapped and counted in a total of 9 sub-sectors (Figure 1).

On each date, the survey was started at or near the time of low tide and continued for 2 to 3 hours, or until the majority of birds had left the estuary. On a spring tide, most birds leave the estuary after mid-tide and fly north-east to the North Bull Lagoons where they ultimately spend the high-tide period. In most situations, a single count in the period 2 hours either side of low tide has been found to be the most accurate reflection of the maximum number of birds present on a site (Burton et al. 2004). All surveys of the Tolka Estuary were carried out in daylight.

Basic analysis has been undertaken to calculate peak counts and trends over the four years. This survey is being continued by BirdWatch Ireland through 2013/14 as part of the Dublin Bay Birds Project which is funded by DPC.


Page 6 of 28 Rev#2 07/02/2014

FFigure 1: Study area for winter bird monitoring in Tolka Estuary (outlined in red). Numbered sections represent count sub-sectors.

2.1.2 Breeding bird surveys

2.1.2.1 Black Guillemots

Black Guillemots breed throughout Dublin Port, mainly in the piers and other structures. They were surveyed using the methods outlined in Mitchell et al. (2004). The survey method involved early morning (05:00-09:00) counts of birds on the water between late March and mid-May at the start of the breeding season. A total of five surveys were undertaken in Alexandra Basin West and a full survey of the Port from Butt Bridge to the Poolbeg Power Station was carried out on 17th May 2013. This survey was boat-based and was undertaken by two experienced observers.

2.1.2.2 Tern colonies

Dublin Port has held a breeding colony of Common Terns and Arctic Terns since at least 1949. In recent years the colony has established on two mooring dolphins close to the Poobeg Power Station and this has been well-monitored since 1995 (Merne 2004). This monitoring has been continued since 2011 by BirdWatch Ireland. A total of six visits were made to the colony, as part of the Dublin Bay Birds Project, between 3rd May and 9th September 2013 to census nesting terns. Breeding productivity of the terns has also been recorded by BirdWatch Ireland.

2.1.3 Bird surveys within the shipping channel and dredge disposal site

A series of six surveys of all birds located within the shipping channel, from Alexandra Basin West to the Dublin Bay Buoy, was undertaken in the period June 2013 to January 2014. The methodology for these surveys followed the standard seabirds-at-sea census technique outlined by Camphuysen et al. (2004).


Page 7 of 28 Rev#2 07/02/2014

The surveys were conducted by two experienced observers from the deck of a vessel, operated by DPC. A number of parallel transects at 600m spacing were followed on each survey. Recording of all birds present was undertaken simultaneously on both sides of the vessel out to a maximum distance of 300m. The study area was subdivided into six survey boxes (marked A to F in Figure 2). Birds were identified to species and their activity was recorded as flying, swimming, roosting, etc. Direction of flight was also recorded.

Figure 2: Study area for seabird surveys in the shipping channel and approaches to Dublin Port. The study area was subdivided into six survey boxes (marked A to F). The numbers 1-8 represent waypoints used for navigation purposes

A single boat-based bird survey of the approved dredge disposal site was carried out on 11th January 2014 (Figure 3). This followed the same methodology, outlined above, as that used for the survey of the shipping channel. Three east-west transects were carried out across the site with all parts of the site visible to within 300m. The survey area was thus divided into three boxes, each approximately 600m wide.


Page 8 of 28 Rev#2 07/02/2014

Figure 3: Location of the approved dredge disposal site (or spoil ground) in Dublin Bay.


Page 9 of 28 Rev#2 07/02/2014

3 DESCRIPTION OF EXISTING ENVIRONMENT

3.1 DESIGNATED AREAS

There are two designated Special Protection Areas (SPA) for birds in the immediate vicinity of the proposed development and a further six SPAs on the wider Dublin coastline, that could have connectivity with the proposed development area. These are considered here because the proposed development may have some indirect impacts on species that are among their special conservation interests. The special conservation interests of these SPAs are listed in Table 1. These SPAs are:

South Dublin Bay and River Tolka Estuary SPA (site code 004024)

North Bull Island SPA (site code 4006)

Skerries Islands SPA (site code 4122)

Rockabill SPA (site code 4014)

Lambay Island SPA (site code 4069)

Ireland’s Eye SPA (site code 4117)

Howth Head SPA (site code 4113)

Dalkey Island SPA (site code 4172)

Table 1. Special Conservation Interests for the SPAs in the areas surrounding Dublin Bay

Special Conservation Interests for Special Protection Areas

Sout

h D

ublin

Bay

and

R

iver

Tol

ka E

stua

ry

Nor

th B

ull i

slan

d

Sker

ries

Isla

nds

Roc

kabi

ll

Lam

bay

Isla

nd

Irela

nds

Eye

How

th H

ead

Dal

key

Isla

nd

Greylag Goose ● Light-bellied Brent Goose ● ● ● Shelduck ● Teal ● Pintail ● Shoveler ● Oystercatcher ● ● Ringed Plover ● Golden Plover ● Grey Plover ● ● Knot ● ● Sanderling ● ● Purple Sandpiper ● ● Dunlin ● ●


Page 10 of 28 Rev#2 07/02/2014

Special Conservation Interests for Special Protection Areas So

uth

Dub

lin B

ay a

nd

Riv

er T

olka

Est

uary

Nor

th B

ull i

slan

d

Sker

ries

Isla

nds

Roc

kabi

ll

Lam

bay

Isla

nd

Irela

nds

Eye

How

th H

ead

Dal

key

Isla

nd

Black-tailed Godwit ● Bar-tailed Godwit ● ● Curlew ● Redshank ● ● Turnstone ● ● Fulmar ● Cormorant ● ● ● Shag ● ● Roseate Tern ● ● ● Common Tern ● ● ● Arctic Tern ● ● ● Black-headed Gull ● ● Lesser Black-backed Gull ● Herring Gull ● ● ● Kittiwake ● ● ● Common Guillemot ● ● Razorbill ● ● Puffin ●

3.2 BIRD POPULATIONS WITHIN DUBLIN PORT

3.2.1 Wintering birds

3.2.1.1 Brent Geese

Flocks of Brent Geese use the Alexandra Basin West between approximately November and April each winter. These birds breed in the high arctic of Northern Canada and migrate to Ireland in September and October. Initially, they forage on intertidal vegetation in Dublin Bay but, as the natural resources are depleted, they switch to feeding primarily on amenity grasslands around Dublin City (Benson 2009). The berths at Alexandra Basin West are used for the unloading of agricultural products and occasional spillage of these materials attracts flocks of Brent Geese to forage here from about November onwards.

The principal attraction for the geese in Alexandra Basin West is the spilt agricultural products that accumulate on the quays (mainly on Berths 29 to 31 and on Ocean Pier). For most of each day, a large flock is present swimming within the Basin. When there is no disturbance on the quayside, the geese fly up to feed intensively on the agricultural products. A peak of 450 geese was counted in Alexandra Basin West in both winters 2012/13 and 2013/14. The threshold for an internationally or nationally important site is one used regularly by over 260 geese (Boland and Crowe 2012).


Page 11 of 28 Rev#2 07/02/2014

A number of the Brent Geese has been colour-ringed by the Irish Brent Goose Research Group and these birds carry individual alpha-numerical codes that can be easily read from a stationary vehicle on the quay. A total of 11 individual ringed geese were identified in Alexandra Basin West in the period January to April 2013 and a further 10 ringed birds were identified in the period November 2013 to January 2014. The full resighting history of these marked individuals indicates that they use a wide variety of both intertidal and inland sites from Kilcoole Marshes in Co Wicklow to Baldoyle Bay in north Dublin.

Several of the individual geese have already been recorded repeatedly in Alexandra Basin West with at least 14 marked birds recorded more than once at the site and five marked birds resighted in both winters 2012/13 and 2013/14. One individual has been recorded in this flock on seven separate dates. This confirms that there is a high degree of site faithfulness and that some of the geese are becoming habituated to this food source.

Within the Dublin-Wicklow area, the birds commute around a large number of sites (mostly on amenity grassland). They often move between sites within the same day, largely due to disturbance (Benson 2009). While ships are unloading in Alexandra Basin West, the geese do not feed on the quay but most revert to feeding on nearby grassland. This was evident on 29th March 2013, when two of the ringed geese previously recorded in the Basin on 10th March were feeding in a flock at Irishtown Nature Reserve. Ringed geese, recorded regularly at Alexandra Basin West, have also been recorded feeding at Irishtown Stadium on the south side of Dublin Port. As the only attraction for the geese in Alexandra Basin West is the source of food in the agricultural products, they are likely to occur wherever these cargos are offloaded in the future.

These geese are widely travelled, making annual return migrations each year from arctic Canada, passing through Iceland, Northern Ireland (and occasionally Scotland) en route to Ireland, where they winter each year (Boland and Crowe 2012, Inger et al. 2006, Robinson et al. 2004). Brent Geese wintering in Ireland have shown a consistent increase since the early 1990s and Dublin Bay area now holds the largest single group in the Republic of Ireland, with a peak of 5,290 geese in the period 2004/05-2008/09 (Boland and Crowe 2012). This makes the Dublin area of special importance and the conservation of this sector of the population is vital to the overall stability of the species.

3.2.1.2 Wintering birds in the Tolka Estuary

The Tolka Estuary is the nearest intertidal area to the Alexandra Basin West and to the Liffey Channel for shipping entering the Basin. The estuary is not covered in the monthly IWeBS1 counts as these are normally concentrated during the high tide period when most of the estuary is covered by water and the majority of the birds have moved to the Bull Island lagoons (Crowe 2005, 2006). Monitoring of birds in the Tolka Estuary has been undertaken, on behalf of DPC, over the four winters 2009/10 to 2012/13. Table 2 gives a summary of the main species recorded over this period.

The Tolka Estuary holds particularly large concentrations of Brent Goose, Oystercatcher, Golden Plover, Knot, Dunlin, Redshank, Black-tailed Godwit, Bar-tailed Godwit, Curlew, Black-headed Gull, Common Gull and Herring Gull. The sum of peak counts for all species in the estuary in 2012/13 was 18,900 birds. This was close to the average of the previous three winters (19,080 birds). The total number of birds wintering in the entire area of Dublin Bay has been relatively stable over the last decade, although a decline was recorded in 2010/11 for the first time since 2003/04 (Crowe et al. 2012). The mean of peak counts in Dublin Bay over the last five winters is 31,700. The Tolka Estuary is thus a very important sub-site, especially at low tide, when it holds the majority of all the birds in Dublin Bay.

1 IWeBS is the Irish Wetland Bird Survey organised by BirdWatch Ireland.


Page 12 of 28 Rev#2 07/02/2014

Table 2. Overall mean of all counts and mean of peak counts for each species in the Tolka Estuary during the four winters 2009/2010 to 2012/2013.

Species Scientific Name Overall mean

Mean Peak

Mute Swan Cygnus olor 0 4 Brent Goose Branta bernicla 312 855 Shelduck Tadorna tadorna 9 37 Mallard Anas platyrhynchos 1 3 Wigeon Anas penelope 10 41 Teal Anas crecca 1 3 Pochard Aythya ferina 0 2 Tufted Duck Aythya fuligula 0 1 Goldeneye Bucephala clangula 1 3 Red-breasted Merganser Mergus serrator 12 33 Cormorant Phalacrocorax carbo 3 9 Red-throated Diver Gavia stellata 0 0 Little Grebe Tachybaptus ruficollis 0 0 Great Crested Grebe Podiceps cristatus 11 35 Little Egret Egretta garzetta 1 3 Grey Heron Ardea cinerea 7 14 Oystercatcher Haematopus ostralegus 316 458 Ringed Plover Charadrius hiaticula 0 0 Grey Plover Pluvialis squatarola 20 63 Golden Plover Pluvialis apricaria 177 789 Lapwing Vanellus vanellus 0 1 Knot Calidris canutus 541 2,251 Sanderling Calidris alba 2 12 Turnstone Arenaria interpres 34 67 Dunlin Calidris alpina 1,214 3,915 Redshank Tringa totanus 366 677 Greenshank Tringa nebularia 1 5 Black-tailed Godwit Limosa limosa 73 283 Bar-tailed Godwit Limosa lapponica 690 1,419 Curlew Numenius arquata 281 498 Black-headed Gull Choicocephalus ridibundus 2,225 6,673 Common Gull Larus canus 68 251 Herring Gull Larus argentatus 247 544 Lesser Black-backed Gull Larus fuscus 14 62 Great Black-backed Gull Larus marinus 10 26 Black Guillemot Cepphus grylle 0 1 Total waterbirds 19,035

3.2.2 Breeding birds

3.2.2.1 Black Guillemots

Dublin Port holds a sizeable colony of breeding Black Guillemots, estimated at a minimum of 82 adult birds in May 2013. This could be considered as a loose breeding colony of at least 41 pairs (Figure 4). The birds breed throughout the Port in disused drainage pipes and other cavities, especially in the older piers and structures. A total of five early morning surveys of Alexandra Basin West were undertaken in April and May 2013. A peak of 16 birds was recorded in Alexandra Basin on 17th May 2013. This equates to eight breeding pairs and represents approximately 20% of the population in Dublin Port. The


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birds are very active in the early morning and commute in and out of the Port via the main Liffey channel. They feed on fish caught in shallow waters of Dublin Bay.

Black Guillemots are relatively common and widespread around the Irish coastline although, unlike most colonial seabirds, they rarely occur in large concentrations. Natural nest sites are generally in crevices at the base of rocky cliffs but they are also commonly nest in harbour walls and even in artificial nest boxes (Mitchell et al. 2004).

Figure 4: Results of a survey of Black Guillemots in Dublin Port on 17th May 2013. Figures refer to individual birds. Alexandra Basin is indicated by a blue rectangle.

3.2.2.2 Breeding Terns

Dublin Port has held a breeding colony of Common Terns (Sterna hirundo) and Arctic Terns (S. paradisaea) since at least 1949 and this has been well-monitored since 1995 (Merne 2004). The terns breed mainly on two mooring structures (known as the ESB and CDL dolphins) on the south side of the River Liffey, near the Poolbeg power station. The birds are generally present on these structures from May to August and numbers have been increasing steadily since the 1990s. In 2011, 499 pairs of Common Tern and 37 pairs of Arctic Tern bred and well over 700 chicks were ringed. Data for 2012 are not available but in late summer the majority of the chicks were predated on the nests and productivity was low (S. Newton, pers comm.).

A total of six visits were made by BirdWatch Ireland to the colony in 2013, between 3rd May and 9th September, to assess the success of the breeding season. At least 418 pairs of Common Terns nested on the ESB platform, and at least 25 pairs of Arctic Tern and one Common Tern nested on the CDL platform. The overall mean clutch size of Common and Arctic Tern nests combined was 2.40. A total of 449 Common Terns and 33 Arctic Terns were ringed. While breeding productivity could not be accurately calculated, the estimated minimum productivity, calculated as the number of fledged chicks


Page 14 of 28 Rev#2 07/02/2014

per egg-laying pair, was 1.05 and 1.38 for Common and Arctic Terns respectively. No evidence of mammalian predators was recorded on either of the platforms in 2013. However a minimum of 69 eggs were depredated by avian predators (BirdWatch Ireland, unpublished data). This suggests a slight decrease in the size of the colony since 2011. It is likely that the structures used are at maximum capacity and that there is little space for any expansion here. In 2013, a single pair of Common Terns also nested successfully on a moored raft in the Tolka Estuary to the north of Dublin Port. Both species of terns can occasionally be seen feeding in the wake of large ships entering and leaving the port. Terns are occasionally recorded in Alexandra Basin West but do not regularly feed there.

3.2.2.3 Other bird species

A number of other bird species have been recorded regularly in Alexandra Basin West, although none of these (apart from pigeons) have been recorded breeding here. These are summarised in Table 3.

Table 3. Other bird species recorded in Alexandra Basin in 2013

Species Scientific name Frequency

Grey Heron Ardea cinerea Single bird regularly recorded at the west end of the Basin

Cormorant Phalacrocorax carbo Occasionally recorded roosting on jetties in the centre of the Basin

Mallard Anas platyrhynchos One or two pairs in the Basin throughout the year Peregrine Falco peregrinus Single bird occasionally recorded hunting pigeons

in the Basin Black-headed Gull Chroicocephalus ridibundus Flocks regularly forage on spilt agricultural products

on the quays. Herring Gull Larus argentatus Small numbers of birds feed and roost in the Basin. Great Black-backed Gull Larus marinus Small numbers of birds feed and roost in the Basin.

Occasionally prey on Black Guillemot. Grey Wagtail Motacilla cinerea One or two birds recorded at the west end of the

Basin Feral Pigeon Columba livia (domest.) Large flocks feed throughout the year on spilt

agricultural products on the quays

3.3 BIRD POPULATIONS IN THE SHIPPING CHANNEL

Birds using the shipping channel and approaches to Dublin Port had not been surveyed prior to 2013 except in the section between the Tolka estuary and the Great South Wall where small numbers of Cormorant, Shag, Great Crested Grebe and Red-breasted Merganser are frequently recorded in winter (see Table 2).

From June 2013 to January 2014 a series of six dedicated boat-based surveys of seabirds in the shipping channel area was undertaken. The area covered was from the Alexandra Basin West to the outermost limit of dredged channel at the Dublin Bay Buoy. The study area was divided into a series of six survey boxes as shown in Figure 2 and all parts of these were covered to within a distance of 300m. The overall results of the surveys are given in Table 4.

The most abundant species throughout the surveys was Black-headed Gull with a peak of 665 in September. The majority of these birds were roosting on and around the outfall from the Ringsend Wastewater Treatment Works. A large flock of Kittiwake was also foraging in the inner port in June but was not recorded for the rest of the year. Common and Arctic Terns were common in the port in June to August (the main breeding season) but were largely absent later on. Black Guillemots also used the shipping channel regularly during the breeding season (June and July) but were relatively scarce after that. Significant numbers of Cormorants and Herring Gulls use the port and shipping channel for foraging and roosting throughout the year and Common Guillemots were also present in most surveys.


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The flock of Brent Geese recorded in January was feeding within Alexandra Basin West but moved to the shipping channel when disturbed. Most other species occurred irregularly or in small numbers.

Table 4. Total number of birds recorded in the shipping channel from June 2013 to January 2014

Species Scientific name Jun Jul Aug Sep Nov Jan Mean Peak

Great Northern Diver Gavia immer 0 0 0 0 0 4 1 4

Great Crested Grebe Podiceps cristatus 0 0 0 0 2 3 1 3

Manx Shearwater Puffinus puffinus 0 1 0 0 0 0 0 1

Gannet Morus bassanus 21 8 0 7 0 0 6 21

Cormorant Phalacrocorax carbo 84 90 131 138 107 73 104 138

Shag Phalacrocorax aristotelis 5 3 6 15 27 21 13 27

Grey Heron Ardea cinerea 0 1 0 0 0 0 0 1

Brent Goose Branta bernicla hrota 0 0 0 0 9 301 52 301

Shelduck Tadorna tadorna 2 0 0 0 0 0 0 2

Wigeon Anas crecca 0 0 0 0 0 11 2 11

Teal Anas crecca 0 0 0 0 4 0 1 4

Oystercatcher Haematopus ostralegus 0 0 0 0 0 1 0 1

Black-tailed Godwit Limosa limosa 0 0 0 0 2 0 0 2

Turnstone Arenaria interpres 0 10 6 0 0 0 3 10

Mediterranean Gull Larus melanocephalus 0 6 3 4 2 1 3 6

Black-headed Gull Chroicocephalus ridibundus 8 58 292 665 502 634 360 665

Common Gull Larus canus 1 7 5 0 3 59 13 59

Lesser Bl-backed Gull Larus fuscus 1 4 0 0 0 0 1 4

Herring Gull Larus argentatus 64 66 156 74 33 113 84 156

Great Bl-backed Gull Larus marinus 3 10 8 5 2 21 8 21

Larus gulls Larus species 0 0 0 1 0 61 10 61

Kittiwake Rissa tridactyla 138 0 0 1 0 0 23 138

Gull species Unidentified gulls 0 0 0 1 0 0 0 1

Sandwich Tern Sterna sandvicensis 3 1 1 1 0 0 1 3

Roseate Tern Sterna dougallii 0 2 0 0 0 0 0 2

Common Tern Sterna hirundo 46 173 121 0 0 0 57 173

Arctic Tern Sterna paradisaea 27 20 4 0 0 0 9 27

Common/ Arctic Tern Sterna species 86 245 5 1 0 0 56 245

Common Guillemot Uria aalge 36 7 56 56 77 61 49 77

Razorbill Alca torda 0 0 0 5 52 0 10 52

Black guillemot Cepphus grylle 50 56 5 4 8 13 23 56

3.4 BIRD POPULATIONS AT THE APPROVED DREDGE DISPOSAL SITE

The proposed disposal of dredged material will take place on the approved disposal site in the winter months. A single boat-based survey of this area was carried out on 11 January 2014. The results of this survey are given in Table 5.


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Table 5. Summary of seabird species recorded at the approved dredge disposal site on 11th January 2014

Box Totals Species North Central South

Herring Gull 2 2 1 5

Common Guillemot 41 23 20 84

Razorbill 2 0 0 2

Total 45 25 21 91

Common Guillemot was the predominant species recorded in the dredge disposal site in January. This species is widespread in the Irish Sea throughout the year. Densities of birds in the inshore area are markedly higher in the summer months as there are large breeding colonies on Lambay and on some of the coastal headlands in the east of Ireland (Pollock et al. 1997).

Previous boat-based surveys of seabirds have been carried out on the Kish Bank, which lies approximately 4.5 nautical miles to the east of the approved dredge disposal site. Although these surveys covered a much larger area of sea surface, Common Guillemots were also the most abundant species recorded in this area in the winter months. Analysis of the full year surveys undertaken for the Dublin Array Windfarm in 2001 and 2010, showed that Common Guillemot was the most numerous species on both surveys although the 2001 survey recorded considerably higher peak numbers (14,218) than the 2010 survey (6,932) (Saorgus Energy Ltd., 2013).


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4 LIKELY SIGNIFICANT IMPACTS

4.1 ALEXANDRA BASIN WEST REDEVELOPMENT

4.1.1 Description of proposed development

The redevelopment of Alexandra Basin West will include construction of new quays and jetties; remediation of contamination on the bed of the basin; capital dredging to deepen the basin and to achieve specified depths of up to -10m CD at the new berths (further detail is contained in Chapter 4). The dredging will involve removal of circa 0.47 million cubic metres of mainly silty material from the Alexander Basin West most of which is contaminated or partially contaminated.

A suite of sampling and environmental testing has been undertaken to quantify and identify the nature of the contamination within the bed materials of Alexandra Basin West. The results show that the bed material is contaminated with heavy metals such as Arsenic, Copper, Chromium, Cadmium, Nickel, Lead, Mercury and Zinc. High levels of contamination were measured within Alexandra Basin West at depths exceeding 2.0m. This material is deemed to be unsuitable for disposal at sea.

Dredging of contaminated material within Alexander Basin West will be undertaken to the design dredge level for the scheme. The dredging will be undertaken using a floating pontoon with an excavator mounted clamshell bucket adapted for environmental dredging. This will minimise the disturbance and escape of material at the seabed and during removal through the water column. A silt curtain will be utilised around the dredger whilst the dredging of contaminated material is ongoing. These will serve to reduce the spread of suspended contaminated sediments beyond the dredge foot print. The dredged material will be loaded onto barges to be transported to a treatment facility at Berths 52/53. In order to minimise the stockpiling of dredged material, the rate of dredging will be determined by the rate of treatment of the dredged material (see Chapter 4). Further details of the project proposal are set out in the NIS (Section 2.1) and are informed by Chapter 4 of the ABR Project EIS (RPS, 2014).

4.1.2 Impacts on birds

Brent Geese are present in Alexandra Basin West each winter from approximately November to April. The geese are attracted to feed on spilt agricultural products on the quays, mainly on Berths 29-33. They also swim in flocks on the water in the Basin. These birds move frequently between different parts of Dublin Bay and the species is one of the special conservation interests of the two Special Protection Areas in Dublin Bay. Numbers of geese recorded in Alexandra Basin West peaked at 450 birds in both winters 2012/13 and 2013/14. Recording of marked birds indicates that there is a high degree of site fidelity among the individual geese using the Basin.

Redevelopment of the quays and jetties in the Basin will take place on a phased basis so that shipping can continue to use parts of the Basin at all times. As agricultural products will continue to be unloaded here, albeit in different locations, the geese will continue to be attracted to the spillages. They are already habituated to high levels of shipping activity and associated noise so that construction noise is unlikely to have any additional effects. The geese will tolerate vehicles to a distance of less than 20m so it is likely that they will not be disturbed by construction vehicles. While the geese do swim on the surface of the Basin, they do not feed while on the water. They will thus not be exposed to contaminated sediments during the dredging operations. It is concluded that there will be no significant impact of this part of the proposed development on wintering Brent Geese within Alexandra Basin West.

Black Guillemots are present in the Alexandra Basin West, mainly in spring and summer months. A maximum of 16 birds was recorded within the Basin in May 2013 and this represents about 20% of the total breeding population in Dublin Port. The birds breed in cavities within the existing quays and jetties, including a number of disused drainage pipes. These cavities will be removed preceding the redevelopment works to prevent their use by the birds during demolition. Mitigation measures will be introduced to provide alternative nest sites in neighbouring areas of the port, in advance of the


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redevelopment. Black Guillemots are rarely seen foraging in the water areas of the Basin as it is unlikely that their preferred fish prey occurs here in sufficient density.

The breeding tern colonies on the mooring dolphins in Dublin Port are sufficiently remote from the Alexandra Basin West (approximately 2km) and will not be directly affected by the redevelopment works. Terns are rarely recorded flying within the Basin, as it is unlikely that their preferred fish prey occurs here in sufficient density. The dredging of spoil from the Basin will not therefore have any indirect impacts on breeding terns.

The other incidental bird species, listed in Table 3, either forage on the spilt agricultural products in Alexandra Basin West (Mallard, Feral Pigeon, Grey Wagtail) or roost on some of the jetties (Herring Gull, Great Black-backed Gull, Grey Heron). None of these species will be significantly affected by the proposed development.

4.2 INFILL OF THE BERTHS 52/53 BASIN


The proposed development includes the infilling of the Berths 52/53 Basin at the eastern end of the north port. This will be followed by the construction of a new river berth with a double-tiered Ro-Ro ramp (see Project Description in the NIS, Section 2.1). The dredged material recovered from Alexandra Basin West will be transported by barge to a treatment facility adjacent to Berth 52/53. It will be stabilised and modified to improve the engineering properties of the material, to allow its re-use as fill material for reclamation works identified within the Port. As part of this scheme it is proposed to fill Berth 52/53 to provide open storage space and a new river berth at the port entrance. The contaminated dredge material from the Alexander Basin West will be used for the fill material. The material will be treated and placed in Berth 52/53.


There are no significant intertidal areas within the Basin occupied by Berths 52 and 53. This is a confined deep water area and does not hold any significant numbers of birds in winter. The Basin will be fully contained within a new steel pile wall prior to reclamation. This will prevent any escape of fill material to the Liffey channel or to the wider areas of Dublin Bay. Thus, no significant impacts on wintering birds are predicted.

The only breeding birds present in the vicinity of Berths 52/53, are Black Guillemots which use the area mainly in spring and summer months. A maximum of 4 birds was recorded within this Basin in May 2013 and this represents about 5% of the total breeding population in Dublin Port. The birds breed in cavities within the existing quays and jetties. These cavities will be removed preceding the redevelopment works to prevent their use by the birds during demolition. Mitigation measures will be introduced to provide alternative nest sites in neighbouring areas of the port, in advance of the redevelopment. Black Guillemots are rarely seen foraging in the water areas of the Basin as it is unlikely that their preferred fish prey occurs here in sufficient density. The infilling of this area will not cause any significant impacts on Black Guillemot.

4.3 CAPITAL DREDGING OF THE APPROACH CHANNEL


The proposed development includes dredging of the Approach Channel to Dublin Port to a level of -10m CD, extending from the North Wall Quay Extension (downstream of the East Link Bridge) to Dublin Bay


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Buoy. This equates to circa 5.9 million cubic metres of dredging (excluding the 0.47 million cubic metres from the Alexandra Basin West).

In order to negate any potential impact of the channel dredging on Poolbeg Marina, it is proposed to construct a surge protection/retaining wall along the edge of navigation channel adjacent to the Marina. This structure will also serve to protect vessels moored in the marina from the wash produced by long vessels (circa 340m in length) manoeuvring about the North Wall Quay Extension.

The dredging of the Approach Channel will be carried out over a period of approximately six years with the main works confined to winter months. The dredging will involve the removal of 3.2 million cubic metres of mainly fine sand in the outer channel and 2.7 million cubic metres of mainly silty material from the inner channel. The sediment quality of the material to be dredged within the approach channel has been tested for contamination and is deemed suitable for disposal at sea. There is however an area immediately adjacent to Alexandra Basin West where low levels of contamination have been identified requiring this material to be disposed of at sea only at low tide and immediately covered by sand or gravel.

The uncontaminated material from the channel will be dredged to the required design depths by a trailer suction dredger or equivalent. The dredged material will be loaded into barges and transported directly to the licensed sea disposal site located at the entrance to Dublin Bay (subject to the granting of a Dumping at Sea Permit by the EPA).

It is envisaged that the dredging of uncontaminated material will be carried out during winter months only (October to March) to negate any potential impact on salmonid mitigation and summer bird feeding, notably terns, in the vicinity of the dredging operations.


4.3.2.1 Direct impacts of dredging

The shipping channel is used by a range of seabirds and other species throughout the year (see Table 4 above). The dredging works in the channel will be carried out in phases over six to ten years. The work will be confined to winter months (October to March) and will thus not affect birds foraging during the breeding season. Maintenance dredging was carried out in the channel in 2012 and no significant changes in bird populations in the Tolka Estuary area in winter 2012/13 were recorded, that could be connected with the dredging activity. All birds using Dublin Port shipping channel and approaches are habituated to high levels of shipping activity. A single dredging vessel, involved in the proposed capital dredging for this project, would not cause any significant additional disturbance potentially affecting wintering waterbirds and seabirds within the shipping channel.

4.3.2.2 Indirect or long-term impacts of dredging

The intertidal areas of the Tolka Estuary, which are adjacent to the shipping channel to the west of the Poolbeg lighthouse, are an important habitat for wintering birds (see Table 2 above). The simulations carried out for this project have modelled the deposition of suspended sediment during the dredging process at Alexandra Basin West. This indicated that circa 0.2 to 0.8g/m2

of silt sediment would be deposited in the harbour channel and surrounding berths. It is expected that this volume of sediment would result in a maximum increase in the sea bed thickness of circa 8x10-5

mm and would be very unlikely to result in any adverse impacts on the physical environment. The deposition of suspended material in the Tolka Estuary has been shown to be less than 0.002kg/m3, which equates to a deposition of less than 0.0002mm. This will have no significant impact on the intertidal areas of the Tolka Estuary. The results of the modeling also indicate that the low levels of contaminants in the channel, outside of Alexandra Basin West are unlikely to require special dredging techniques to prevent sediment loss during dredging (RPS, 2014).


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Dredging of the proposed channel to -10mCD will not significantly alter the tidal regime, wave climate or sediment transport regime in Dublin Bay away from the immediate area around the entrance channel at the approaches to the Bull walls and the harbour channels. The proposed channel to -10mCD is unlikely to be susceptible to rapid infilling and will have a similar stability to the existing channel. It is therefore concluded that there will be no significant impacts of the dredging on surrounding intertidal areas within Dublin Bay, either in the short-term or long-term. There will thus be no indirect effects on waterbirds in these locations.

A review of the impacts of capital and maintenance dredging in the Tamar estuary, in south-west England, was published by Widdows et al. (2007). This estuary is a Special Protection Area under the EU Birds Directive which requires annual maintenance dredging as well as occasional capital dredging for new installations. Maintenance dredging here involves annual removal of between 5,000 and 200,000 tonnes of dry sediment per year. During two periods of capital dredging in the Tamar, the amount of sediment dredged was between 500,000 and 700,000 tonnes per year. Annual estimates for ten species of wildfowl and waders were analysed over several decades in the Tamar Estuary. There were no significant correlations between overwintering bird numbers and dredging activity. Declines in Teal and Wigeon over 30 years were related to milder winters which changed the migratory patterns of these species.

Fish-eating birds, such as Black Guillemots, Cormorants or terns, can be sensitive to increasing turbidity as they use their eyes to chase and capture their prey under water. A review of ecological effects of dumping of dredged sediments in the Netherlands was published by Essink (1999). The increase in turbidity in the Dutch coastal zone since the 1960s was considered as a possible cause of reduced breeding success of Sandwich Tern breeding in the Wadden Sea area, caused by the greater distance from the breeding colony that adult terns have to fly in order to obtain sufficient prey for their young (Essink 1999).

The large breeding colony of Common Terns within Dublin Port has been monitored closely since 1995. Breeding productivity (number of fledged young per nesting pair) between 1995 and 2002 averaged 1.50 (range 1.20 to 1.79) (Merne 2004). In 2013 the estimated productivity for this colony was in the range 1.05 to 1.91 (median 1.48) (BirdWatch Ireland, unpublished data). This suggests that the overall productivity of the terns is relatively stable over the medium term and has not been negatively affected by dredging of the Liffey Channel in 2012. The breeding colonies in Dublin Port are principally occupied by terns from late April to August. From July to September, large flocks of migratory terns gather in Dublin Bay and roost on Sandymount Strand (Merne et al. 2008). By early October, the majority of these birds have left the bay completely. As the proposed dredging of the navigation channel will take place in winter months only (October to March inclusive), when the terns are absent, there will be no residual increase in suspended sediments from dredging by the time the terns return to the colonies in late April.

Black Guillemots, which also breed within Dublin Port, are rarely seen foraging within the Liffey channel but most frequently feed in the wider area of Dublin Bay and are seen returning to the nest sites carrying small fish. They are mainly present here in spring and summer but only small numbers are present in the channel in autumn and winter (see Table 4). Thus, they will not be significantly impacted by the dredging works which will take place in the winter months only.

It is concluded that the capital dredging of the shipping channel will have no significant impacts on birds in the channel itself or in the surrounding intertidal areas of the Tolka Estuary or other intertidal parts of Dublin Bay.


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4.4 DISPOSAL OF DREDGED MATERIAL IN THE APPROVED DREDGE DISPOSAL SITE

4.4.1 Description of the proposed development

The best option for the disposal of the dredged spoil is considered to be sea disposal at the existing approved dredge disposal site (see Figure 3). A series of computational model simulations were undertaken to assess the dispersion and fate of the material which is to be disposed of at the site to the west of the Burford Bank. The particle size distribution analysis of the sediment samples detailed in the ABR Project EIS (RPS, 2014) concluded that are essentially two different types of material that comprise the sea bed of the outer approach channel and the inner harbour channel. The material in the sea bed of the approach channel is generally composed of fine sand while the material in the sea bed of the harbour channel and berths generally comprises primarily fine silty material and a small proportion of coarser silt sediment. The model simulations showed that suspended sediment concentrations during the disposal of the dredged sand material away from the immediate area of the dump site will be very low, with mean values of less than 0.02mg/L. Thus, virtually all of the sand deposited on the dump site will remain on the site under normal tidal conditions. The model simulations also showed the maximum and mean suspended sediment concentration (SSC) of the silt fractions envelop during the disposal of the silty material. The maximum value of SSC away from the immediate area of the dump site will not exceed 90mg/L. The mean SSC gives the average value of the suspended sediment in the water column over the period of the dredged spoil disposal, which is a more realistic and representative measure of the impact of the spoil disposal on the suspended concentration of the water column and surrounding environment. The average SSC due to the disposal of the dredged spoil material will be 30mg/L above background concentrations in the vicinity of the edge of the dump site and reduces to about 17mg/L within about 4.5 kilometers from the dump site. 4.4.2 Impacts on birds

The boat-based survey in January 2014 showed that Common Guillemot was the most abundant species recorded within the approved dredge disposal site in winter. Other species recorded in very small numbers were Herring Gull and Razorbill. While a range of other seabird species may occur within the site, at other times, there is no evidence to confirm that birds present in the approved dredge disposal site in winter are connected with the seabird breeding colonies on Howth Head, Lambay or Ireland’s Eye.

The disposal of dredged material in the approved disposal site will take place entirely in the winter months (October to March). The fine sediment elements of the dredged material are predicted to disperse in a plume on each tide. Turbidity at the approved disposal site will be elevated as dumping at this location is ongoing; however, suspended solids levels will return to background levels within a period of days, following the completion of dumping in March each year. For the remainder of each year the predicted concentrations of suspended sediment in the affected area will be low and would not have any significant effect on the foraging ability of seabirds in this area during the period when they are breeding within some of the nearby SPAs. There will thus be no residual effects on seabirds in the following breeding seasons. It is concluded that the disposal of dredged material will have no significant impacts on birds in the approved disposal area itself or in the surrounding parts of the Irish Sea. 4.5 OVERALL IMPACTS ON SPECIAL PROTECTION AREAS IN DUBLIN

COASTAL AREA

There are two Special Protection Areas (SPAs) in inner Dublin Bay and a further six SPAs on the wider Dublin coastline that may have connectivity to the Dublin Port area (section 3.1 above). There will be no direct overlap of the SPA boundaries by the Alexandra Basin West redevelopment, infill of Berths


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52/53 Basin, capital dredging of the Liffey channel or disposal of dredged material in the approved dredge disposal site. Some of the Special Conservation Interests of these SPAs occur within Dublin Port, the shipping channel and the approved dredge disposal site (Table 7) although there is no scientific evidence linking any of the species present in winter with individual breeding colonies.

Table 7. Special Conservation interests of SPAs recorded within Alexandra Basin West, the Dublin Port Shipping Channel or the Approved Dredge Disposal Site.

Sout

h D

ublin

Bay

and

R

iver

Tol

ka E

stua

ry

Nor

th B

ull i

slan

d

Sker

ries

Isla

nds

Roc

kabi

ll

Lam

bay

Isla

nd

Irela

nds

Eye

How

th H

ead

Dal

key

Isla

nd

Occ

urs

in A

lexa

ndra

Ba

sin

Occ

urs

in D

ublin

Por

t Sh

ippi

ng C

hann

el

Occ

urre

nce

in th

e ap

prov

ed d

rdeg

e di

spos

al s

ite

Light-bellied Brent Goose ● ● ● √ √

Shelduck ● √

Teal ● √

Oystercatcher ● ● √

Black-tailed Godwit ● √

Turnstone ● ● √

Cormorant ● ● ● √ √

Shag ● ● √

Roseate Tern ● ● ● √

Common Tern ● ● ● √

Arctic Tern ● ● ● √

Black-headed Gull ● ● √ √

Lesser Black-backed Gull ● √

Herring Gull ● ● ● √ √ √

Kittiwake ● ● ● √

Common Guillemot ● ● √ √ Razorbill ● ● √ √

4.5.1 Alexandra Basin West Redevelopment

Of these special conservation interests, only the Light-bellied Brent Goose occurs in significant numbers within Alexandra Basin West. It is concluded in section 4.1.2 that there will be no significant impact of the proposed development on wintering Brent Geese within Alexandra Basin West as the development will be carried out in phases and agricultural products will continue to be offloaded at different berths within the port. The geese will adapt quickly to any new source of feeding. Black-headed Gulls and Herring Gulls also forage on the spilt agricultural products but these will continue to be available both during and after construction. Cormorants roost in small numbers on some of the jetties within the Basin. There are abundant alternative roost sites within the Port and these will remain available both during and after construction. None of the special conservation interests, listed in Table 7, occurs within the existing Berths 52/53 and there will be no indirect effects of the development of this area on the SPAs.


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4.5.2 Capital dredging of Shipping Channel

The frequency of occurrence of the various Special Conservation Interests in the Shipping Channel and the type of activity of these species is outlined in Table 8. Seven of the species are infrequent and have only been recorded flying over the channel. These species will not be affected by the dredging activity. Common Tern and Arctic Tern occasionally forage in the channel in summer months but, as these are absent in winter, they will not be affected by the dredging works.

Table 8. Special Conservation Interests of SPAs and their frequency of occurrence within the Dublin Port Shipping Channel and approved dredge disposal site

Species Frequency Activity within the channel

Light-bellied Brent Goose Infrequent Flying over the channel Shelduck Infrequent Flying over the channel Teal Infrequent Flying over the channel Oystercatcher Infrequent Flying over the channel Black-tailed Godwit Infrequent Flying over the channel Turnstone Infrequent Flying over the channel Cormorant Frequent Foraging and roosting on jetties and navigation buoys Shag Frequent Foraging and roosting on jetties and navigation buoys Roseate Tern Infrequent Flying over the channel Common Tern Frequent Roosting on navigation buoys Arctic Tern Frequent Roosting on navigation buoys Black-headed Gull Frequent Foraging and roosting on jetties and navigation buoys Lesser Black-backed Gull Frequent Foraging and roosting on navigation buoys Herring Gull Frequent Foraging and roosting on navigation buoys Kittiwake Frequent Foraging Common Guillemot Frequent Foraging Razorbill Frequent Foraging

Black-headed Gulls do not breed in the Port and the large flocks that forage and roost in the Liffey channel will be unaffected by the proposed capital dredging because they mainly feed in the vicinity of the outfall from Ringsend Waste Water Treatment Works, which will not be affected by the proposed dredging works. The three tern species and Kittiwake are present in the Port and on the shipping channel only during the summer months (April to August). As the proposed dredging of the navigation channel will take place in winter months (October to March inclusive), when these birds are absent, they will be unaffected by the proposed development. None of the other species, listed in Table 7 or 8, is likely to be affected in a significant way by the proposed development. There is no evidence that any of the seabird species present in the Shipping Channel in winter, is linked with the SPAs in the Dublin area. These birds are known to range widely outside the breeding season and many of the breeding birds from Dublin seabird colonies may have dispersed to other parts of the North Atlantic in winter (Mitchell et al. 2004).

The nearest parts of any SPA to the Liffey Channel are in the Tolka Estuary, which is largely intertidal. The likely deposition of suspended material in the Tolka Estuary has been shown to be less than 0.002kg/m3, which equates to a deposition of less than 0.0002mm (RPS, 2014). This will have no significant impact on the intertidal areas of the Tolka Estuary or on the Special Conservation Interests for the SPA or any of the other SPAs listed in Table 7. As the Conservation Objectives for all SPAs are “To maintain or restore the favourable conservation condition of the bird species listed as Special Conservation Interests”, it is concluded that there will be no significant impacts on these Natura 2000 sites, either during construction or operation of the Alexandra Basin West redevelopment.


Page 24 of 28 Rev#2 07/02/2014

4.5.3 Disposal of dredged material in the approved dredge disposal site

The settlement and/or dispersal of the dredged material in the approved dredge disposal site is summarised in section 4.4.1. As the material will be deposited in the winter months and will quickly settle to the seabed or disperse in low concentrations, there is no risk that it may affect the foraging activity of seabird species, which are Special Conservation Interests of the SPAs in the Dublin coastal region, during the breeding season. While such species may be present in winter, there is no proven connection between the individual wintering birds and the SPA sites. It is concluded that the disposal of dredged material will have no significant impacts on birds which are among the Special Conservation Interests of the SPAs on the Dublin coastline.


Page 25 of 28 Rev#2 07/02/2014

5 MITIGATION MEASURES

5.1 ALEXANDRA BASIN REDEVELOPMENT AND INFILL OF BERTHS 52/53

5.1.1 Brent Geese

The Brent Geese that regularly use Alexandra Basin West in winter have adapted to feeding on spilt agricultural products. Redevelopment of the quays and jetties in the Basin will be carried out on a phased basis so that shipping can continue to use parts of the Basin at all times. As agricultural products will continue to be unloaded here, albeit in different locations, the geese will continue to be attracted to the spillages. No other mitigation measures are required for this species.

5.1.2 Black Guillemots

Black Guillemots readily nest in artificial sites including disused drainage pipes and other cavities in quays and jetties in both Basins. The birds generally come ashore and occupy the nest holes in October, some five months prior to egg-laying (Greenwood 1987, 1991). Young birds have generally left the nests by late August (Ferguson-Lees et al. 2011). In order to avoid disturbance to nesting birds, any existing nest holes in piers to be demolished, will be blocked or otherwise made inaccessible in the month of September preceding the development works. Prior to this, temporary artificial nest boxes (10 No.) will be provided for the birds in immediately adjacent parts of the port, for the duration of construction works. In addition, concrete nest boxes (10 No.) will be incorporated into the new quays and jetties, at appropriate locations selected at the detailed design stage, to encourage the birds to return to these areas in subsequent breeding seasons.


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6 CONCLUSIONS

With full implementation of the mitigation measures outlined in section 5, there will be no significant impacts of the proposed development on either breeding birds or wintering birds within the Port or the Liffey Channel or in the approved dredge disposal site. It is concluded that there will be no significant impacts of the proposed development on the Conservation Objectives of the Special Protection Areas in Dublin Bay or neighbouring coastlines.


Page 27 of 28 Rev#2 07/02/2014

7 REFERENCES

Benson, L. 2009. Use of inland feeding sites by Light-bellied Brent geese in Dublin 2008-2009: a new conservation concern. Irish Birds 8: 563-570.

Boland, H. and Crowe, O. 2012. Irish Wetland Bird Survey: waterbird status and distribution 2001/02-2008/09. BirdWatch Ireland. Kilcoole.

Burton, N.H.K., Musgrove, A.J. and Rehfisch, M.M. 2004. Tidal variation in numbers of waterbirds: how frequently should birds be counted to detect change and do low tide counts provide a realistic average? Bird Study 51: 48-57.

Camphuysen, C.J., Fox, A.D., Leopold, M.F. and Petersen, I.K. 2004. Towards standardised seabirds and sea census techniques in connection with environmental impact assessments for offshore windfarms in the UK. Report commissioned by COWRIE. Royal Netherlands Institute for Sea Research. Texel. The Netherlands.

Crowe, O. 2005. Ireland’s Wetlands and their Waterbirds: Status and Distribution. BirdWatch Ireland. Newcastle.

Crowe, O. 2006. A review of the wintering waterbirds of Dublin Bay. 1994/95 to 2003/04. Irish East Coast Bird Report 2002: 123-129.

Crowe, O., Boland, H. and Walsh, A. 2012. Irish Wetland Bird Survey: Results of waterbird monitoring in Ireland in 2010/11. Irish Birds 9: 397-410.

Dublin City Council 2012. Ringsend Waste Water Treatment Works Extension. Environmental Impact Statement. Chapter 9: Terrestrial Flora and Fauna. Dublin City Council.

Essink, K. 1999. Ecological effects of dumping of dredged sediments; options for management. Journal of Coastal Conservation 5, 69-80.

Ferguson-Lees, J., Castell, R. and Leech, D. 2011. A Field Guide to Monitoring Nests. British Trust for Ornithology. Thetford.

Greenwood, J.G. 1987. Winter visits by Black Guillemots Cepphus grille to an Irish breeding site. Bird Study 34, 135-136.

Greenwood, J.G. 1991. Duration of winter visits by Black Guillemots Cepphus grille to an Irish breeding site. Seabird 13, 67-69.

Inger, R., Ruxton, G.D., Newton J., Colhoun, K., Robinson, J.A., Jackson, L. and Bearhop, S. 2006. Temporal and interpopulation variation in prey choice of wintering geese determined by stable isotope analysis. Journal of Animal Ecology 75, 1190-1200.

Merne, O.J. 2004. Common Sterna hirundo and Arctic Terns S. paradisaea breeding in Dublin Port, County Dublin, 1995-2003. Irish Birds 7, 369-374.

Merne, O.J., Madden, B., Archer, E. and Porter, B. 2008. Autumn roosting by terns in south Dublin Bay. Irish Birds 8, 335-310.


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Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. 2004. Seabird Populations of Britain and Ireland. T. & A.D. Poyser. London.

Pollock, C., Reid, J., Webb, A. and Tasker, M. 1997. The distribution of seabirds and cetaceans in the waters around Ireland. JNCC Report No. 267. Joint Nature Conservation Committee. Aberdeen.

Robinson, J.A., Colhoun, K., Gudmundsson, G.A., Boertmann, D., Merne, O.J., O Briain, M., Portig, A.A., Mackie, K. and Boyd, H. 2004. Light-bellied Brent Goose Branta bernicla hrota (East Canadian High Arctic Population) in Canada, Ireland, Iceland, France, Greenland, Scotland, Wales, England, the Channel Isles and Spain 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee. Slimbridge.

RPS (2014) Alexandra Basin Redevelopment Project Environmental Impact Statement (EIS). RPS.

Saorgus Energy 2013. Dublin Array: An Offshore Windfarm on the Kish and Bray Banks. Environmental Impact Statement Addendum. Appendix C. Assessment of Potential Impacts on Bird

Widdows, J., Bale, A.J., Brinsley, M.D., Somerfield, P. and Uncles, R.J. 2007. An assessment of the potential impact of dredging activity on the Tamar Estuary over the last century: II. Ecological changes and potential drivers. Hydrobiologia 588, 97-108.


Marine Mammals Impact Assessment

App

endi

x B

A report on the potential effects of Dublin Port development on marine

mammals

January 2014

Dr. M Cronin & Dr. M. Jessopp

2

TABLE OF CONTENTS 1. Introduction ................................................................................................................ 3

2. Legislation pertaining to marine mammals in Irish waters ........................................... 3

3. Marine Mammals in the area ...................................................................................... 4

3.1 Cetaceans ................................................................................................................... 4

3.1.1. Harbour Porpoise ................................................................................................. 4

3.1.2. Bottlenose Dolphin ............................................................................................... 5

3.1.3. Minke Whale ........................................................................................................ 6

3.1.4. Common Dolphin ................................................................................................. 6

3.1.5. Risso‟s Dolphin .................................................................................................... 7

3.2 Pinnipeds..................................................................................................................... 7

3.2.1. Harbour seal ........................................................................................................ 8

3.2.2. Grey seal.............................................................................................................. 9

4. Site visit .................................................................................................................... 10

4.1. Methods: ................................................................................................................... 10

4.2. Results: .................................................................................................................... 11

5. Potential impacts of the proposed works on marine mammals and identification of

sensitive receptors. ............................................................................................................. 14

6. Direct, indirect and cumulative impacts of proposed demolition works, piling, dredging

and dumping of dredged material on pinnipeds. .................................................................. 19

7. Direct, indirect and cumulative impacts of proposed demolition works, piling, dredging

and dumping of dredged material on cetaceans .................................................................. 21

8. Assessment of impact magnitude and significance ................................................... 24

9. Mitigation Measures ................................................................................................. 25

10. Residual Impacts ...................................................................................................... 27

11. References ............................................................................................................... 28

3

1. Introduction This report details the potential risks to marine mammals and recommendations for

mitigation measures related to the proposed Alexandra Basin Redevelopment (ABR) Project

in Dublin Port. It is based on a site visit by the author (M. Cronin), information from published

and unpublished literature and communication with local relevant authorities. This report is

based on information on proposed development which involves demolition works, piling,

dredging and dumping of dredge spoil.

2. Legislation pertaining to marine mammals in Irish waters Marine mammals are protected by national legislation and by a number of international

regulations which the Republic of Ireland is signatory to. The main legislation that affords

protection to marine mammals in Irish waters is the Wildlife Act (1976) amendment Act

(2000), which prohibits wilful interference to wild mammals and disturbance of resting and

breeding sites.

All cetacean (whales, dolphins and porpoises) species occurring in European waters are

afforded protection under the EC Habitats Directive (92/43/EEC), of which Ireland is a

signatory. The current transposition of this legislation in Ireland is the EC „Birds and Natural

Habitats‟ Regulations (2011). All cetaceans are included in Annex IV of this Directive as

species „in need of strict protection‟. Additionally the harbour porpoise (Phocoena phocoena)

and bottlenose dolphin (Tursiops truncatus) are designated Annex II species („those animals

of community interest, whose conservation requires the designation of special areas of

conservation‟). Ireland‟s two pinniped (seals) species, the harbour seal (Phoca vitulina) and

grey seal (Halichoerus grypus), are also designated Annex II species under the E.C.

Habitats Directive (1992).

The Republic of Ireland is also signatory to conservation orientated agreements under the

Bonn Convention on Migratory Species (1983); the OSPAR Convention for the Protection of

the Marine Environment of the northeast Atlantic (1992); and the Berne Convention on

Conservation of European Wildlife and Natural Habitats (1979).

In light of the legislation and conservation status of marine mammals, careful assessment

and consideration must be given prior to and during all anthropogenic activity with potential

for effects on these species and their habitat. Lambay Island in Co. Dublin is designated as

a candidate Special Area of Conservation (cSAC) with the grey seal listed a species of

4

qualifying interest and the harbour seal has also recently been added as a qualifying feature.

Furthermore the recently designated Rockabill to Dalkey Island cSAC (designated in 2012)

overlaps with the proposed dredge material dump site. Harbour porpoise is listed as a

qualifying interest for this site, as it is an Annex II species under the Habitats Directive.

Please note that the proposed capital dredging scheme also extends into the new Rockabill

to Dalkey cSAC. As there are other cSACs within Dublin Bay (with habitats, flora and fauna

other than marine mammals listed) in accordance with Article 6.3 of the Habitats Directive,

An Appropriate Assessment screening has been carried out by RPS and an AA will be

produced for the proposed project.

3. Marine Mammals in the area

It is necessary to determine what marine mammals use the waters in the vicinity of the

proposed works, and likely extended zone of influence in order to estimate the likely

significance of any impacts resulting from the proposed development.

3.1 Cetaceans

Based on species‟ ecology and sighting records cetacean species likely to use the area of

Dublin Bay and the dump area at Burford bank include harbour porpoises (Phocoena

phocoena), bottlenose dolphins (Tursiops truncatus), minke whales (Balaenoptera

acutorostrata), Risso‟s dolphins (Grampus griseus) and common dolphins (Delphinus

delphis) (Evans, 1992, Berrow et al., 2001; 2008; Ingram, 2000; Ingram et al., 2001 and

2003; Rogan et al., 2001; Ó Cadhla et al., 2004; O Brien et al., 2009; IWDG, 2013).

An overview and literature review for each cetacean species occurring within and likely to

occur within the study area is set out below.

3.1.1. Harbour Porpoise Sightings of Europe‟s smallest cetacean species, the harbour porpoise, have been relatively

common off all coasts of Ireland and in the Irish Sea (Northridge et al., 1995; Hammond et

al., 1995; Pollack et al., 1997; Berrow et al., 2001; Ó Cadhla et al., 2004; Anderwald et al.,

2011). The small size of harbour porpoises and their erratic surfacing behaviour can make

them difficult to detect. There are however relatively frequent sightings of the species within

Dublin Bay, including the dredge disposal site and shipping channel (IWDG, 2013). Surveys

of harbour porpoise carried out at specific sites around the Irish coast identified Dublin Bay

5

as an important area for the species, with high densities in Dublin Bay of 1.19 per km2

reported, representing one of the highest densities of the species recorded in Ireland to date

(Berrow et al., 2008). Surveys of cetaceans in the waters outside of Dublin Bay, in the

western Irish Sea, indicated that harbour porpoise were by far the most abundant species in

the area with relative abundance of harbour porpoise estimated at 0.55 porpoise per kmkm2

(Berrow et al., 2011). Sighting rates of harbour porpoise, and thus local densities, were

notably higher adjacent to Rockabill and Lambay Islands. This was consistent with Berrow et

al. (2008) who recorded high densities during smaller scale harbour porpoise surveys in the

same area. This suggests that this could be a good habitat for harbour porpoises. The

Rockabill to Dalkey Island cSAC is designated for the conservation and protection of this

species. The proposed dredge material dump site at the Burford Bank overlaps with this

cSAC site boundary.

Harbour porpoises produce high-frequency sounds used for echolocation and

communication, but do not make frequency-modulated whistles typical of many delphinids.

The high frequency sounds are comprised entirely of click trains, produced in two narrow

band frequency components, one between 1-20 kHz and the other between 120-160 kHz

(peaking around 125-130 kHz) (Goodson et al., 1995). Maximum source level is estimated at

between 149 and 177 dB re 1µPa at 1 m (Akamatsu et al., 1992).

Harbour porpoises are very sensitive to vessel noise and activity and are unlikely to

approach areas of high activity (Polacheck & Thorpe, 1990). However it is the cetacean

species most likely to be affected by the proposed works considering the importance of the

area for harbour porpoise. Mitigation measures outlined in Section 9 of this report will

minimize potential impacts of the proposed works on this species.

3.1.2. Bottlenose Dolphin A coastal species of cetacean commonly sighted in western Irish waters (Evans, 1992,

Pollock et al., 1997) bottlenose dolphins are numerous on the south and west coasts

(Ingram and Rogan, 2003; Ingram et al., 2001, 2003). There are resident communities in the

waters of the outer Shannon estuary (Ingram, 2000; Ingram and Rogan, 2003) and a

transient population recorded off all Irish coasts (O Brien et al., 2009). Bottlenose dolphins

have been occasionally recorded in Dublin Bay (IWDG 2013). However the area is not

significant at national level for bottlenose dolphins and the dolphins sighted there are likely

to be part of a transient population. Bottlenose dolphins are a wide-ranging species and

individuals commonly travel between coastal regions especially during the summer months

(Ingram et al., 2003).

6

The bottlenose dolphin makes a wide range of vocalisations. Echolocation clicks (used for

orientation and foraging) are composed of intense short duration broadband clicks (40-130

kHz) (Au, 1993). Burst pulse vocalisations may have a variety of social functions (0.2-16

kHz). Whistles are pure tone frequency modulated calls ranging from 2-20 kHz. Clicks and

whistle vocalisations can be made simultaneously.

Bottlenose dolphins may be attracted to vessel activity, making them potentially vulnerable

to physical harm from industrial activities, including dredging. Mitigation measures set out in

Section 9 of this report will minimize potential impacts of the proposed works on this species.

3.1.3. Minke Whale The most common species of baleen whale found around Irish coasts, the minke whale is

frequently recorded around all parts of the west coast (Pollock et al., 1997, Berrow et al.,

2002; Ó Cadhla et al., 2004). Research conducted in UK waters suggest that the species

moves southwards to inshore Atlantic Margin waters in spring and summer, remaining until

late autumn following which numbers decline (Pollack et al., 2000; Northridge et al., 1995).

The minke whale has been sighted in near inshore waters around Ireland and of all whale

species that use Irish waters is the species with the most near-shore distribution, and

therefore potentially the most vulnerable to anthropogenic noise resulting from development

in the marine environment Vocalisations of minke whales involve intense, low frequency,

broadband (0.5-1 kHz bandwidth) and harmonic down-sweeps with maximum source level of

165 dB re 1 re 1µPa at 1m (Edds, 1988).

Minke whales have been sighted in outer Dublin Bay (IWDG, 2013) and it is possible they

occasionally use the proposed dredging/dumping area at Burford Bank. There were six

sightings of individual minke whales off the Dublin Coast during cetacean surveys of the

north Irish Sea in 2011, with most sightings east of Rockabill and Lambay Island off north

County Dublin (Berrow et al., 2011). Mitigation measures set out in Section 9 of this report

will minimize potential impacts of the proposed works if there is occasional use of the area

by this species.

3.1.4. Common Dolphin Although a mainly oceanic species, common dolphins have been frequently observed in

large schools around the coasts of Ireland (Pollock et al., 1997; Gordon et al., 2000) and it is

the most commonly stranded cetacean around the Irish coast (Berrow & Rogan, 1997). The

7

mobile schools of common dolphins seen in coastal waters tend to be foraging for shoaling

fish species.

Vocalisations of common dolphins vary from whistles of 1-50 kHz frequency (mainly 6-12

kHz, max. source level 172dB re 1µPa at 1 m) to echolocation clicks which may reach 150

kHz (max. source levels 170 dB re 1µPa at 1 m) (Evans, 1973; Moore & Ridgway, 1995).

Clicks and whistles may be given simultaneously.

Common dolphins are attracted to vessels and are easily sighted and identified. It is

considered unlikely that the proposed works within Dublin Port will not impact upon common

dolphins in the area as they do not frequent the waters of inner Dublin Bay; however it is

possible they will occasionally use the area of the outer bay, where the proposed dumping of

dredged material will take place, at the Burford Bank. Mitigation measures set out in Section

9 of this report will minimize potential impacts of the proposed works on this species.

3.1.5. Risso‟s Dolphin In Ireland Risso‟s dophin have generally been recorded close to the coast with highest

numbers of sightings between August and February (Pollack et al., 1997; 2000). A large and

robust species, Risso‟s dolphins are slow moving and often seen in small schools (Berrow et

al., 2002). Risso‟s dolphins will not usually approach vessels but are readily recognised by

their distinctive colouration patterns and large size.

Vocalisations include a variety of clicks, whistles, and pulsed calls. Whistles are rarely

heard, but range over 2.5-20 kHz, maximum source level of 170 dB re re 1µPa at 1 m. Clicks

have peak frequency at 65 kHz and durations of 40-100 secs (Au, 1993).

It is considered unlikely that the proposed works will impact upon this species as there are

no records of this species in Dublin Bay; however, mitigation measures set out in Section 9

of this report will minimize potential impacts of the proposed works if there is occasional use

of the area by this species.

3.2 Pinnipeds

Based on species‟ ecology and sighting records, seal species likely to use the area of Dublin

Bay and the dump area at Burford Bank include harbour seal (Phoca vitulina) and grey seal

8

(Halichoerus grypus). An overview and literature review for both seal species occurring

within and likely to occur within the study area is set out below.

3.2.1. Harbour seal Harbour seals (also known as “common seals”) have established themselves at terrestrial

colonies (or haul-outs) along all coastlines of Ireland, which they leave when foraging or

moving between areas, for example, and to which they return to rest ashore, rear young,

engage in social activity. These haul-out groups of harbour seals have tended historically to

be found among inshore bays and islands, coves and estuaries (Lockley, 1966; Summers et

al., 1980), particularly around the hours of lowest tide. Harbour seals in Ireland use

terrestrial sites mainly on the western seaboard, with highest numbers in NW and SW

Ireland (Cronin et al., 2008).

The closest haul-out site of harbour seals to Dublin Bay is Lambay Island where

approximately 30 harbour seals were observed during national census in 2003 (Cronin et al.,

2004), and 2012 (Duck & Morris, 2013). Smaller haul-out groups were also observed at

Skerries Island (3 individuals) and further north at Clogher Head (8 individuals) and Dundalk

harbour (18 individuals) (Cronin et al., 2004). Larger haul-out groups of harbour seals occur

further north in Carlingford Lough. An aerial census of harbour seals in Carlingford Lough

during 2011 recorded a total of 255 harbour seals at haul-out sites within the Lough (SMRU,

unpublished). The number of harbour seals counted during surveys at terrestrial sites

generally represents 60-70% of the seals using the area, as some will be at sea, therefore

using a correction factor on the haul-out count data over 400 harbour seals could potentially

use Carlingford Lough. There are no known harbour seal haul-out sites within Dublin Bay.

Recent findings from tagging harbour seals in SW Ireland suggest that harbour seals are

local foragers, generally staying within 20km of their haul-out sites (Cronin et al., 2008);

however, studies in the UK have shown that harbour seals travel further distances from haul

out sites (over 100km), therefore it is possible that harbour seals from sites in Carlingford

Lough use the waters of Dublin Bay and very likely that harbour seals from haul-out sites on

Lambay and Skerries and Dundalk harbour use Dublin Bay.

Harbour seals are most vulnerable at their terrestrial haul-out sites during breeding and

moulting periods. These events occur between June and September in Ireland.

In addition to the identified terrestrial sites, the surrounding waters surrounding haulout sites

are likely to be critical habitat for harbour seals, for feeding and/or for navigation to more

offshore foraging areas. Results from a study by the author on the haul-out behaviour of

harbour seals in southwest Ireland in recent years suggests that harbour seals spend up to

9

80% of their time at sea (Cronin, 2007; Cronin et al., 2008). Similar behaviour patterns have

been seen in studies of harbour seals in Scotland (Sharples, SMRU pers comm, Thompson

& Miller, 1990). Unlike grey seals, harbour seal adults continue to forage during the breeding

season (Bonnes et al., 1994). In addition the mating strategy is based on males diving and

calling at aquatic display sites (Van Parijs et al., 1997, 2000, Hayes et al., 2004).

Disturbance from anthropogenic noise during this period could potentially affect mating

success. The hearing range of harbour and grey seals extends over wide frequencies,

including the ultrasonic spectrum. The area of best hearing is between 8 and 25 kHz, with

acute hearing also at lower frequencies (Møhl 1968; Terhune & Turnbull 1995). There is

potential for harbour seals using the waters in and in the vicinity of Dublin Bay to be at risk to

potentially detrimental impacts of the proposed piling, dredging and dumping. Mitigation

measures outlined in Section 9 of this report will minimize potential impacts of the proposed

works.

3.2.2. Grey seal Grey seals are distributed throughout Irish coastal waters and commonly seen hauled out on

more exposed shores than the harbour seal (Kiely, 1998). The large colonies of grey seals

on the Irish coastline are predominantly on the western seaboard on the northwest and

southwest coasts and islands; although relatively large numbers of grey seals are also found

in southeast Ireland e.g. Wexford harbour, Saltee Islands (O Cadhla et al., 2007).

A national census of the grey seal population in 2005 identified grey seal breeding sites in

Co. Dublin at Lambay Island, Dalkey Island, Irelands Eye and St. Patricks Island (Ó Cadhla

et al., 2007). Pup counts were small at these sites (less than 3); apart from Lambay where

49 pups were counted. Further surveys conducted in 2009 recorded 77 pups on Lambay

Island and Ireland‟s Eye (Ó Cadhla et al. 2013). These sites are also important to grey seals

during the annual moult (Jan-April) in particular St. Patricks Island and Lambay Island,

where 137 and 110 grey seals respectively were observed during a moult census in 2007 (O

Cadhla & Strong, 2007). A group of 36 grey seals were also observed on Dalkey Island

during the 2007 census and 26 grey seals on Rockabill. Four grey seals were sighted in

Dublin Bay during aerial surveys as part of a harbour seal population survey in

August/September 2012, with a further 62 observed on Lambay Island at this time (Duck &

Morris 2013). This suggests over 300 grey seals use the islands in Co. Dublin, particularly

for moulting. Grey seals are frequently seen in the waters of Dublin Bay at Dun Laoghaire

and Howth harbour, Bull Island and Sandycove. Larger colonies of grey seals occur further

south in Wexford Harbour at Raven Point, where up to 450 grey seals haul-out during the

10

annual moult period (pers. ob.). The Saltee Islands in Co. Wexford are also an important

breeding and moulting site for grey seals.

Grey seals are also most vulnerable at their terrestrial haul-out sites during breeding and

moulting periods. These events occur between September and March in Ireland. The waters

surrounding terrestrial haulout sites are likely to be a critical habitat for grey seals, for

feeding and/or for navigation to more offshore foraging areas. Grey seal have a wider

offshore foraging distribution than harbour seals and therefore grey seals from haul-out sites

in Co. Dublin as well as from the large breeding and moult colonies on the coast and islands

of Co. Wexford will potentially use the waters of Dublin Bay for foraging and/or navigation.

They will therefore be at risk to potentially detrimental impacts of the proposed piling,

dredging and dumping. Mitigation measures set out in Section 9 of this report will minimize

potential impacts of the proposed works.

4. Site visit

A visit to Dublin Bay and site of the proposed works was made by the author (M. Cronin) on

27th and 28th July 2013.

4.1. Methods: The waters in Dublin Bay were surveyed from two vantage points on the north shore of the

harbour (see Fig 2) using a telescope (equipped with a 30x eyepiece) mounted on a tripod

and 10 x 50 Leica binoculars for all marine mammals at sea between 14.00 and 18.00 on

27th July 2013 (2 hours either side of high tide). The two vantage points (A & B) provided

visibility of Dublin Bay, as well as the waters surrounding the bay (Figs. 1-2). The conditions

on July 27th were favourable for visual surveillance, with a Beaufort sea-state of 2-3 and a

light SE breeze. Observations of marine mammals at sea are affected by prevailing sea

conditions with a decline in sighting probability in Beaufort sea-states of three or higher.

The shorelines and waters of Dublin Bay (Fig. 3) were surveyed using 10 x 50 Leica

binoculars for all marine mammals ashore during the low water period between 08.00 and

12.00 (2 hours either side of low water) on 28th July. The low water period was surveyed in

order to maximise the likelihood of observing seals hauled out on the shoreline.

Supplementary data on marine mammal presence was collected during bird surveys in the

area.

11

4.2. Results:

One seal (unidentified species) was observed approximately 300m southeast of

North Bull Island on 27th July at 17.35

Two grey seals were observed approximately 100m from shore at Dun Laoghaire on

28th July at 10.30

While no cetaceans were observed during the dedicated visual observations, this

does not indicate that the area is not visited by dolphins or porpoises particularly

given the transient nature of cetacean movement patterns. Supplementary visual

observations by consultants undertaking visual surveys for birds recorded three

harbour porpoise at the outer channel near the Dublin Bay Buoy on 25th June, and

three further harbour porpoise between North Bull Light and Buoy 3 at the north side

of the outer channel on 26th August 2013.

Figure 1 Map of Dublin Bay and proposed channel alignment (source RPS)

12

Figure 3 Waters of outer Dublin Bay scanned for marine mammals at high tide

A B

Figure 2 Dublin Bay and location of observation points A, B for marine mammal survey (source: Google Earth)

13

Figure 4 Alexandra Basin West, Dublin Port.

Figure 5 Shore of Dublin Bay scanned for marine mammals

14

5. Potential impacts of the proposed works on marine mammals and identification of sensitive receptors.

Studies on the responses of marine mammals to anthropogenic noise have identified the following factors as influencing the degree of response given by animals (Anguilar et al., 2004):

(i) source intensity levels;

(ii) degree of background noise;

(iii) distance to source;

(iv) species involved;

(v) behavioural state and season;

(vi) prior degree of exposure;

(vii) age, sex ; and

(viii) time of day.

The peak pressure, duration and the frequency spectrum of anthropogenic sound are

important factors relating to potential biological impacts. Several studies have examined the

direct and indirect impacts of underwater noise on marine mammals, and in general have

indicated that source levels of 180-200dB P-P re 1 μPa are sufficient to induce behavioural

effects on marine mammals within a few kilometres from the sound source (Gausland,

2000). Biological damage from high-level sound may be categorized as either direct injuries

(lethal, sub-lethal or non-lethal) or indirect effects (changes in behaviour or distribution

patterns).

Playback experiments of drilling sounds in the presence of cetaceans have shown

avoidance reactions and reduction of calling rates by various baleen whale species

(Richardson et al., 1995). Phocid seals are more sensitive than small odontocetes to noise

of low frequency and are therefore potentially more susceptible to disturbance from low

frequency anthropogenic noise (Thompson et al., 1998). Consequently, both harbour seal

and grey seal will be susceptible to disturbance from underwater anthropogenic noise

associated with demolition works when at sea.

Pile driving associated with the proposed development is considered to be a potentially

detrimental activity to marine mammals because it produces a very high source level and

broad bandwidth pulse, which is biased towards the lower frequencies. Sound produced

during pile-driving propagates through the air into water, through the water column and, to a

lesser degree, through the sediment and from there back into the water column (Thompson

15

et al., 2006). Sound pressure levels in impact pile-driving are dependent on the length and

the diameter of the pile and the impact energy (Nedwell et al., 2003) as well as the seabed

conditions or substrate hardness. The response thresholds of cetaceans are usually the

lowest for pulsed sounds and pile driving is one of the loudest sources of this type of noise

(Richardson & Wursig, 1996). Peak source levels of 228 dB re 1 μPa @ 1m have been

estimated for 1.5m diameter jacket-piles (ITAP 2005). The piles to be used in the

development in Dublin Port are circa 1.6m diameter.

Extended exposure to high levels of continuous noise and/or impulsive sounds with high rise

times can lead to injuries of the hearing structures in cetaceans and pinnipeds resulting in

permanent or temporary hearing loss and other injuries (Richardson et al., 1995). Source

levels of pile-driving noise are very similar to tactical sonar, which has been linked to noise-

related injuries (Evans & Miller, 2004). However piling noise differs in duration, frequency

content, duty cycle and directionality, and it is therefore difficult to assess their potential for

causing severe injury in cetaceans and pinnipeds based on current evidence. Animals close

to the source, exposed to a sudden onset of pile-driving noise might be injured (Thomsen et

al., 2006). Temporary threshold shift (TTS), a temporal elevation of the hearing threshold

due to noise exposure, could be induced by exposure to pile-driving noise. In addition to

potentially injuring marine mammals, pile driving and industrial noise can adversely impact

behaviour, communication and breeding with effects from some operations detected at

distances of up to 20km for harbour porpoises and harbour seals (Thomsen et al., 2006).

Behavioural modifications including the haulout behaviour of pinnipeds (Teilmann et al.,

2006) and echolocation in harbour porpoise (Tougaard et al., 2003) have also been

observed during pile driving activities. The literature contains some reference values for

biological thresholds for onset of PTS, TTS and behavioural changes integrated over a

duration of 1 second, as well as accumulation of sound energy over a continuous 24-hour

period (Southall et al., 2007; Lucke et al., 2009). These thresholds are listed in Table 1

below. Sound propagation in the marine environment is context specific and largely

dependent on water depth, bathymetry, sediment type, oceanographic conditions and

ambient noise levels. Furthermore, behavioural responses depend on many factors including

the properties of the sound source, species, age, condition, sex, season, social state and

existing behaviour (Richardson et al. 1995). For these reasons, obtaining accurate and

reliable predictions of the zone of PTS, TTS and behavioural responses is complex, and

involves the interplay of a large number of variables. Available evidence based on examples

obtained from published literature are mostly site specific and hence should be regarded as

merely indicative in the context of the proposed works.

16

Mitigation measures are proposed in Section 5.2.9 to reliably quantify the zone of responsiveness associated with the proposed programme of piling activities associated with the Alexandra Basin Redevelopment.

Table 1. Thresholds for onset of PTS, TTS and behavioural response to impulsive

anthropogenic noise (following Southall et al., 2007 and Lucke et al. 2009).

Species Approx. frequency range of sensitivity

Sound Exposure Level (dB ref 1μPa2s) Behaviour

Disturbance Threshold (BDT)

Temporary Threshold Shift

(TTS)

Permanent Threshold Shift

(PTS)

1 second 24 hours 1 second

24 hours

1 second

24 hours

Harbour porpoise

0,200-180kHz 145(*) 162 164(*) 181 198(#) 215(#)

Dolphin spp 0,150-160kHz ? ? 183(#) 195 198(#) 215(#)

Harbour/ grey seal

0,075-75kHz ? ? 171(#) 188 186(#) 203

(#) Southall et al. (2007) (*) Lucke et al. (2009)

The most likely impact of the proposed dredging and infilling in the harbour, and dumping in

the outer bay will be through sound disturbance and local habitat modification. Benthic

dredging activity results in significant short to medium term modification to the biological

environment. Destruction of benthic communities through substrate removal and smothering

of benthic communities through plumes and dumping of dredge spoil will displace many

species of invertebrate and fish, and may subsequently affect the food chain and impact on

marine predators at a local scale. However, the effects of substrate removal will be

determined by the extent of dredging activity and the value (in terms of foraging or

conservation) of the existing habitat. Grey seals and cetacean species are highly mobile,

with ranges that are likely to overlap with the dredging and dumping works. In addition to the

physical act of sediment removal, dredging activities will result in potential disturbance to

marine mammals through increases in vessel activity and increase local ambient marine

noise levels.

There are limited studies describing dredging noise from North America and the UK,

covering a variety of dredger types. The sparse data available indicate that vibration levels

close to the source are relatively small and that dredging is not as noisy as seismic surveys,

pile driving and sonar; but it is louder than most shipping, operating offshore wind turbines

and drilling. Thomsen et al. (2009) suggest it should be viewed, therefore, as a medium

impact activity and because of its continuous nature, which might last for extended periods,

the potential adverse effects, especially in areas of high ecological sensitivity should not be

overlooked.

17

Noise associated with dredging is predominantly of low frequency, below 1 kHz; estimated

source sound pressure levels range between 168dB and 186dB re 1μPa at 1m. In most

cases the noise is continuous in nature. Audibility of dredging noise is dependent on many

factors (hearing sensitivity of the species in question, prevalent ambient noise, transmission

loss etc). Since dredging noise is predominantly of low frequency, it would potentially affect

low frequency cetaceans such as minke whales to a greater extent than mid or high

frequency cetaceans. The harbour porpoise is a potential exception, as it has a relatively

high sensitivity across most frequencies. There is also a potential issue with seals as both

harbour and grey seals have relatively good underwater hearing at frequencies below 1kHz

(Thomsen et al., 2009).

Studies have shown that in shallow water, which would also characterise the situation at

most dredging sites, received sound pressure levels were above 140dB re 1μPa,

respectively at 1km distance from the source; a value that is probably detectable for most

marine mammals sensitive to sound pressure, depending on hearing abilities and local

ambient noise conditions. Even at 10km distance, sound pressure levels were well above

120dB re μPa, a value which might exceed ambient noise levels in several areas (Thomsen

et al., 2009).

Most of the information on diet in porpoises comes from an examination of the stomach

contents of stranded animals or animals taken in fisheries by-catch. It has been suggested

that porpoise are opportunistic feeders, altering their diet in response to prey availability at

any given time and while this behaviour is difficult to prove there is some, at least weak,

evidence to support it (Santos and Pierce 2003). Both porpoises and seals feed on pelagic,

demersal and benthic species although they are believed to feed mainly close to or on the

seabed. Dredging can remove large amounts of seafloor sediment along with associated

benthic communities, with potential loss of foraging opportunities for marine mammals. The

dredging of the shipping channel is likely to reduce the feeding quality for a range of benthic

and demersal fish species for at least one season after the dredging, which in turn may

reduce the density of fish feeding in the affected areas. However, it won‟t eliminate fish from

the site as they were present there in 2013 despite channel dredging in 2012. Furthermore,

only about 20% of the channel is earmarked to be dredged each year over the lifetime of the

project, thereby restricting the footprint of the impact each year. It is unlikely, that porpoises,

which tend to avoid areas of busy port traffic, feed much in the inner part of the channel, so

that dredging in these areas is less likely to impact the species. Indeed a survey of the

18

distribution of the species based on sightings from a boat (Berrow, 2008) found that

porpoises were almost absent from the inner and middle part of Dublin Bay.

The dumping of dredged material of fine sand and silt has the potential to affect water quality

and create a plume effect which will travel according to local water currents. The main tidal

currents in the area of the Burford Bank are in a north-south direction, away from the

intertidal areas of Dublin Bay, with fine sediment particles being transported northwards

before settling out in the northern part of the Irish Sea (Anon, 2013). This may have a

temporary impact on marine mammals‟ visibility in the immediate vicinity of the vessel and

dump site. Dumping is likely to have a similar impact to dredging on fish feeding within and

immediately adjacent to the dredge spoil dumpsite as noted for the dredge channel above,

i.e. a reduction in feeding density of fish due to suppression in macroinvertebrate food

density following each 6 months of spoil disposal. Unlike much of the dredged channel which

may not be the site of foraging by porpoises, or at least be used to a minor degree, the

species are recorded in the general area of the dump (Berrow, 2008), although not in the

same intensity as the waters around Howth peninsula. If we consider the fact that the

dumpsite has been utilised on a fairly constant basis for more than 10 years and is therefore

likely experience a regular, periodic suppression of benthic fish production, then it is

reasonable to suggest that the area is unlikely to be a critical feeding area for porpoises.

This is further supported when it is considered that the waters adjoining the site to the north,

east and south are important nursery grounds for several of porpoises‟ most important prey

species (i.e. whiting, cod and herring). For these reasons, it is expected that the project will

not have a significant adverse impact on the local population and any displacement of

marine mammals resulting from impacts on available prey are unlikely.

To summarise, the potential effects of demolition works, piling, dredging and dumping on

marine mammals include;

1 Physical injury or death of individuals resulting from collisions with operator

vessels.

2 Physical injury or death of individuals resulting from close-range exposure to pile-

driving noise.

3 Chronic hearing damage or disturbance/displacement as a result of piling or

dredging noise.

3 Consumption of contaminated prey items resulting from contaminants entering

the food chain (this is only a problem where contaminated substrates are

disturbed).

19

4 Temporary impact on marine mammals‟ visibility should they intersect the

sediment plume during the dumping of dredged material.

5 Changes in prey availability due to local changes in benthic ecology caused by

accumulation of dredge spoil on the seabed.

The likelihood and scale of each of these effects can be estimated and appropriate

precautionary mitigation measures can be employed to reduce the estimated effects.

6. Direct, indirect and cumulative impacts of proposed demolition works, piling, dredging and dumping of dredged material on pinnipeds.

The noise associated with implementation of the ABR Project represents a source of

acoustic degradation in the marine environment. The proposed development and dredging

of the channel within the harbour and bay are unlikely to cause detectable impacts on seals

at the population level. However sightings by the author (M. Cronin) and local reports show

that seals enter the harbour area, and there is a possibility that impacts may occur on

individual grey or harbour seals entering the works zone. The numbers of seals in the

adjacent coastal areas represent a small fraction of the population, both on the east coast of

Ireland, and at a national level.

There are no known terrestrial sites for grey or harbour seals in the immediate proximity of

the proposed works; and therefore there is no considered threat of physical disturbance to

harbour seals at the haul-out sites by the proposed works. However the waters of Dublin

Bay are likely to be important habitat for grey seals, for feeding and/or for navigation to more

offshore foraging areas. Risks to these animals will be small and with a degree of vigilance

from operators, collisions between seals and dredging vessels as well as excessive

disturbance will be avoided. Strict mitigation measures for the protection of marine mammals

are set out in Section 9 of this report.

Rock-breaking and piling associated with the proposed demolition and construction of quay

walls is considered to be a potentially detrimental activity to marine mammals because it

produces a very high source level and broad bandwidth sound. Extended exposure to

impulsive sounds with high rise times can lead to injuries of the hearing structures in

pinnipeds resulting in permanent hearing loss and other injuries (Richardson et al., 1995).

Animals close to the source, exposed to a sudden onset of pile-driving noise might be

injured (Thomsen et al., 2006). Temporary threshold shift (TTS), a temporal elevation of the

hearing threshold due to noise exposure, could be induced by exposure to pile-driving noise.

Thomsen et al (2006), using a model impact pile-driving broadband sound pressure level of

20

229dBrms re 1 µPa at 1m, based on 1.5m diameter piles and scaled up by 10dB for larger

diameter piles, estimated the resulting TTS-zone for pinnipeds as 400m. In this regard, it is

unlikely that piling will result in significant PTS and TTS effects on seals in the area if

appropriate mitigation is carried out. However, pile driving and industrial noise can also

impact behaviour, communication and breeding. Pile driving in the western Baltic has been

shown to effect the haul-out behavior of harbour seals up to 10km from the construction site,

however the effect was of short duration and overall number of seals remained the same

during the whole construction phase (Edren et al., 2004). The potential impact of the

proposed works on the haul-out behaviour of seals and important annual events such as

breeding and moulting is negligible as there are no significant seal haul-out sites within

10km of the proposed works. The radius of the zone of behavioural responses to pile-driving

noise has been provisionally defined as up to at least 20km for harbour seals (Thomsen et

al., 2006), which overlaps with observations of seals in Dublin Bay, although given the

uncertainties in defining responses, it is impossible to quantify the significance at the local

population level.

Noise levels from vessels or from the dredging process are highly unlikely to cause hearing

damage to exposed seals provided they have the opportunity to leave the affected works

area. As the received sound pressure levels can be 140 dB re 1 μPa at 1 km distance from

the source, a value that is detectable for seals, and as the area is of ecological importance,

appropriate mitigation measures are proposed to minimise acoustic disturbance to seals, as

described in Section 9 of this report.

Some of the material to be dredged has been identified as containing contaminants. Heavily

contaminated material will be dredged using curtain dredging, treated, and used as infill

during construction works rather than being transported to the dump site. It is proposed to

dispose of some slight/moderately contaminated material at the dump site; where this

material will be covered or capped with uncontaminated dredge spoil. Therefore any

contamination is likely to be extremely limited.

Sediment plumes may present habitat disturbance to local seals foraging in the area. The

dredging and dumping of material, particularly of fine sand and silt, will likely effect water

quality and create a plume effect which will travel according to local water currents. This may

have a temporary impact on marine mammals‟ visibility, particularly in the immediate vicinity

of the vessel, particularly as seals are curious and will often approach vessels. However this

effect will be temporary and dredged material will be transported to the dump site on Burford

Bank. The dump site is in an open body of water approximately 6 nautical miles from

21

Alexandra Basin West and 2 nautical miles outside Dublin Bay in about 20m water depth.

The main tidal currents in the area of the Burford Bank are in a north-south direction, away

from the intertidal areas of Dublin Bay, and the dumping of dredged material is unlikely to

cause any adverse effects on seals in the area. The changes to the benthos in this region

will most likely effect prey availability to seals in the area. Small shoaling fish that occur

regularly in the diet of seals are likely to move away from the disposal area during

operations. However, the disposal site has been used for dredge spoil disposal for several

decades, with the benthos and demersal fish species subject to periodic smothering, and the

dump site is not a known „hotspot‟ for seal foraging. Therefore, any displacement resulting

from impacts on available prey are unlikely and temporary, with fish returning to the area at

the completion of dumping activity. Mitigation measures set out in Section 9 of this report will

be followed to minimise any potential impact of dredging and dumping on individual seals.

7. Direct, indirect and cumulative impacts of proposed demolition works, piling, dredging and dumping of dredged material on cetaceans

The noise associated with the port developments proposed in the ABR Project is a source of

acoustic degradation in the marine environment. The proposed development and dredging

of the channel within the harbour and bay are unlikely to cause detectable impacts on

cetaceans at the population level. However Dublin Bay is an important area for harbour

porpoise. The noise levels from dredging are unlikely to cause hearing damage to exposed

cetaceans provided they do not approach the immediate vicinity of operations and have the

opportunity to leave the affected area. However, recent investigation by Diederichs et al.

(2010) showed a 600m zone of effect of sand extraction on harbour porpoises, with it taking

three times longer before a porpoise was recorded following sand extraction than during

times without sand extraction. After the ship left the area, porpoises were detected at the

usual rate. As the received sound pressure levels from dredging can exceed 140 dB re 1

μPa at 1 km distance from the source, a value that is detectable for most cetaceans (in

particular the auditory range of harbour porpoise and minke whale) and as this is likely to

extend to the cSAC, appropriate mitigation measures be put in place to minimise acoustic

disturbance to cetaceans, as set out in Section 9 of this report.

Piling and demolition works associated with the construction activity is considered to be a

potentially detrimental activity to cetaceans because it produces a very high source level and

broad bandwidth sound. The response thresholds of cetaceans are usually the lowest for

pulsed sounds and pile driving is one of the loudest sources of this type of noise

(Richardson & Wursig, 1996). Extended exposure to impulsive sounds with high rise times

22

can lead to injuries of the hearing structures in cetaceans resulting in permanent hearing

loss and other injuries (Richardson et al., 1995). Animals close to the source, exposed to a

sudden onset of pile-driving noise (in this case piling of 1.6m diameter piles and sheet piles)

might be injured as injury is a concern when the sound pressure level exceeds 180dBrms re 1

µPa at 1m for cetaceans (Thomsen et al., 2006). Temporary threshold shift (TTS), a

temporal elevation of the hearing threshold due to noise exposure, could be induced by

exposure to pile-driving noise. Applying a broadband sound pressure level of 229dBrms re 1

µPa at 1m scaled up by 10dB for larger diameter piles, Thomsen et al. (2006) estimated the

resulting TTS-zone for harbour porpoise as 1.8km. Since the cSAC for harbour porpoise is

outside this range, the likelihood of population-level impacts from TTS is considered

insignificant, and effects on individual cetaceans entering the works area will be insignificant

if appropriate mitigation measures are carried out. However, pile driving and industrial noise

can adversely impact behaviour, communication and breeding. Thomsen et al. (2006) have

provisionally defined a radius for the zone of behavioural response to pile-driving noise as

up to at least 20km for harbour porpoises. At 9kHz this noise is capable of masking strong

dolphin vocalizations within 10-15km and weak vocalizations up to approximately 40km;

behavioural modifications have been observed in bottlenose dolphins in response to noise

produced by pile driving (David, 2006) and the abundance of echolocating harbour porpoise

was found to decrease during pile driving activities in Denmark within 15 km of the

construction site (Tougaard et al., 2003). However it remained inconclusive if the abundance

changes were directly attributable to the construction activities or were related to overall

temporal variation in abundance. More recent data from the field indicate that porpoise

would react to pile driving at received sound exposure levels of approximately 140dB re

µPa2s. Source levels of broadband sheet piling (smaller piles) can be compared to the

original ITAP (2005) values (206dB re µPa2·s), and applying a reasonable transmission loss

of 15 or 20 log (r), we would expect the sound to be reduced to 140dB SEL at a distance of

between approximately 2 - 25km, although this represents only a rough estimate and will be

very site and context specific (Thomsen, pers. comm.). These examples demonstrate the

potential for impacts at a scale that overlaps with the cSAC. Considering the potential for

indirect impacts of pile driving and industrial noise on cetaceans, in particular harbour

porpoise, appropriate mitigation measures to minimise acoustic disturbance to cetaceans,

are set out in Section 9 of this report. There is potential for behavioural effects from piling to

extend into the cSAC. Although behavioural responses to construction noise are considered

to be temporary, with either habituation to the noise source, or normal behaviour resuming

following cessation of the noise-generating activity, planned works involve piling throughout

the year for a period exceeding five years. Behavioural responses depend on many factors

including the properties of the sound source, species, age, condition, sex, season, social

23

state and existing behaviour (Richardson et al. 1995), all of which complicate the task of

determining the nature and significance of behavioural responses. It is therefore

recommended that a precautionary approach be adopted with establishment of a monitoring

programme to determine any effects on harbour porpoise within the cSAC.

It is most likely that any effects of the proposed dredging work in Dublin Port and Dublin Bay

on cetaceans will be minimal provided correct management and communication procedures

are followed. Some of the material to be dredged has been identified as containing

contaminants. Heavily contaminated material will be dredged using curtain dredging, treated,

and used as infill during construction works rather than being transported to the dump site. It

is proposed to dispose of some slight/moderately contaminated material at the dump site;

where this material will be covered or capped with uncontaminated dredge spoil. Therefore

any contamination is likely to be extremely limited.

Sediment plumes may present habitat disturbance to local cetaceans foraging in the area.

The dredging and dumping of material, particularly of fine sand and silt, will likely effect water

quality and create a plume effect which will travel according to local water currents. This may

have a temporary impact on marine mammals‟ visibility, particularly in the immediate vicinity

of the vessel. As with seals, the dredged area is not considered (or known to be) an

important cetacean foraging area and therefore any displacement resulting from impacts on

available prey are unlikely and not considered significant.

The dredge spoil disposal site to the west of the Burford Bank is in an open body of water

approximately six nautical miles from Alexandra Basin West and two nautical miles outside

Dublin Bay in about 20m water depth. However, the site overlaps with the Rockabill to

Dalkey Island cSAC with harbour porpoise listed as a qualifying interest. The main tidal

currents in the area of the Burford Bank are in a north-south direction, away from the

intertidal areas of Dublin Bay. The dumping of large quantities of dredged material may

cause adverse effects on local harbour porpoise populations. Porpoises feed mainly on small

shoaling fishes, with many prey items taken on or close to the benthos (NPWS 2013).

Dumping of dredged material will smother benthic communities, and shoaling fish are likely

to move away from the dump site during operations, with potential loss of foraging

opportunities for harbour porpoise. The disposal site has been used for dredge spoil disposal

for several decades, with the benthos and demersal fish species subject to periodic

smothering, and the dump site is not a known „hotspot‟ for harbour porpoise foraging. Data

on the distribution of cetacean species from January 2009-July 2011 show only a single

harbour porpoise sighting in the vicinity of the Burford Bank with a more inshore/coastal

24

distribution of harbour porpoise and bottlenose dolphin (CDM 2012). Therefore, any

displacement resulting from impacts on available prey are unlikely, will be temporary and are

not considered to be significant. An earlier study also confirmed that the effects of dredging

and dumping at the Burford Bank on harbour porpoise would, at worst, be localised and

temporary (Natura, 2013). It is expected that animals would habituate to stationary vessels,

and would return to foraging in the affected areas when operations area completed (Natura,

2013). However, given the volumes of material to be dumped, and the long time-scale of

these operations, the mitigation measures set out in Section 9 of this report will be followed

to minimise any potential impact of dredging and dumping on harbour porpoise.

To effectively assess cumulative impacts of the proposed works the temporal and spatial

elements of the planned operations needs to be considered. Piling and dredging within the

basin at the same time would increase the potential impacts of sound exposure to marine

mammals therefore simultaneous dredging, demolition and piling should not occur, or should

be strictly limited in the basin to minimise risk.

The dredged material suitable for disposal at sea will be disposed of at the Burford Bank

dump site (subject to license approval), The dredge spoil disposal site has been routinely

used for the dumping of dredged material, and permits have been issued for the dumping of

approximately eight million tonnes of material at this site between 1997 and 2012. It is not

considered to be a significant feeding area for cetaceans or seals and therefore any

displacement resulting from impacts on available prey are unlikely.

8. Assessment of impact magnitude and significance

The proposed piling and dredging in Dublin Port; dredging works within Dublin bay; and

dumping of dredged material the west of the Burford Bank will have little likelihood of direct

impacts on marine mammals in the area at a population level, the scale of effects are

therefore not considered significant. It is however, likely that individual marine mammals

entering the works area will be affected by acoustic disturbance resulting from noise and

boat activity associated with demolition works, piling, dredging, and dumping, and it is

recommended that vigilance as a mitigation measure should be maintained for any marine

mammal approaching the area throughout operations. The proposed works will occur at all

stages of the tide, and there is an increased likelihood of marine mammals using the harbour

at the high tide stage. It is best practise to employ a marine mammal observer to ensure

impacts of coastal works (including piling, demolition, dredging and dumping) are minimised.

Given the proposed works will take place in the vicinity of a candidate Special Area of

25

Conservation (cSAC) for harbour porpoise, the zone of behavioural responses to noise from

piling operations is likely to extend into the cSAC, the uncertainty in assessing the type and

significance of behavioural responses, and the duration of piling works, it is wise to employ a

precautionary approach with regards to impacts on populations within the cSAC. Assessing

and monitoring of the responses of harbour porpoise to noise, particularly within the cSAC,

during construction is recommended.

9. Mitigation Measures

Following guidelines from the National Parks & Wildlife Service (2013) the following

precautionary measures are therefore advised to minimise the risk of direct injury to marine

mammals in the area of operations:

A trained and experienced Marine Mammal Observer* (MMO) should be put in place

during piling, dredging, dumping, and demolition operations. The MMO will scan the

surrounding area to ensure no marine mammals are in a pre-determined exclusion

zone in the 30-minute period prior to operations. It is suggested that this exclusion

zone is 500m for demolition and dredging activities, and 1000m for piling activities

considering the potential risks outlined.

Noise-producing activities shall only commence in daylight hours where effective

visual monitoring, as performed and determined by the MMO, has been achieved.

Where effective visual monitoring is not possible, the sound-producing activities shall

be postponed until effective visual monitoring is possible. Visual mitigation for marine

mammals (in particular harbour porpoise) will only be effective during daylight hours

and if the sea state is 2-3 (Beaufort scale) or less. In the absence of year-round data

on marine mammal use within Dublin Bay, there is no justification for limiting works to

any particular season.

For piling activities, where the output peak sound pressure level (in water) exceeds

170 dB re: 1μPa @ 1m, a ramp-up procedure must be employed following the pre-

start monitoring. Underwater acoustic energy output shall commence from a lower

energy start-up and thereafter be allowed to gradually build up to the necessary

maximum output over a period of 20-40 minutes.

26

Once operations have begun, operations should cease temporarily if a cetacean or

seal is observed swimming in the immediate (<50m) area of piling and dredging and

work can be resumed once the animal(s) have moved away.

Dumping of material at sea should not take place if a cetacean or seal is within 50m

of the vessel.

Any approach by marine mammals into the immediate (<50 m) works area should be

reported to the National Parks and Wildlife Service.

If there is a break in piling activity for a period greater than 30 minutes then all pre-

activity monitoring measures and ramp-up (where this is possible) should

recommence as for start-up.

Once normal operations commence (including appropriate ramp-up procedures),

there is no requirement to halt or discontinue the activity at night-time, nor if weather

or visibility conditions deteriorate, nor if marine mammals occur within a radial

distance of the sound source that is 500m for dredging and demolition works, and

1000m for piling activities.

The MMO will keep a record of the monitoring using a „MMO form location and effort

(coastal works)‟ available from the National Parks & Wildlife Service (NPWS) and

submit to the NPWS on completion of the works.

Further more detailed guidance on the above can be found in NPWS (2013)

In order to reliably quantify the zone of responsiveness associated with the proposed

programme of piling activities associated with the Alexandra Basin Redevelopment,

one of the following methods will be used:

o Modelling of sound propagation calibrated using field measurements; or

o Deployment of hydrophones in combination with passive acoustic monitoring.

*A qualified marine mammal observer (MMO) is a visual observer who has

undergone formal marine mammal observation training (JNCC MMO training course

or equivalent) and has a minimum of six weeks marine mammal survey experience

at sea over a three year period. MMO‟s for use in Ireland should have field

27

experience in marine mammal monitoring in European waters and be familiar with

the Irish regulatory procedures relevant to the activity to which they are assigned, in

order to ensure compliance. MMOs should have at least three years experience in

surveying/identifying harbour porpoise as the area is important for this species and

they are difficult to visually detect even in a favourable sea-state.

10. Residual Impacts

With full implementation of the mitigation measures outlined in section 9, there will be no

significant impacts of the proposed development on mammal mammals, including harbour

porpoise. It is concluded that there will be no significant impacts of the proposed

development on the Conservation Objectives of the Special Areas Conservation in Dublin

Bay or neighbouring coastlines, including the Rockabill to Dalkey Island cSAC.

The changes to benthos in the dump area will have potential impacts on prey availability to

marine mammals in the area but as it is not known to be a critical foraging area for marine

mammals any effects will be negligible on both the population as well as the individual level.

Behavioural responses to noise from dredging and construction are considered to be

temporary and limited to the duration of the works, and will be reduced for the duration of the

works with the implementation of the proposed mitigation measures. The residual impacts of

the proposed work on marine mammals are considered to be insignificant.

28

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dolphins (Tursiops truncatus) in Connemara coastal waters, Co Galway. Report to the Heritage Council (Ireland) Report no.12314. 25pp. ITAP (2005). Ermittlung der Schalldruck- Spitzenpegel aus Messungen der Unterwassergeräusche von Offshore-WEA und Offshore- Rammarbeiten. Institut für technische und angewandte Physik GmbH. Report commissioned by Biola (Biologisch-landschaftsökologische Arbeitsgemeinschaft).

IWDG (2001). http://www.iwdg.ie/iscope/sightings/ Ketten, D. R., Lien, L. & Todd, S. (1993). Blast injury in humpback whale ears: Evidence and implications. Journal of Acoustical Society of America, 94, 3, 2:1849-1850. Kiely, O.R.M. (1998). Population biology of grey seals (Halichoerus grypus Fabricius 1791) in western Ireland. Unpublished PhD. thesis, University College Cork. Ireland. Lockley, R.M. (1966). The distribution of grey and common seals on the coasts of Ireland. Irish

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Coastal Processes Modelling (RPS, 2014)

App

endi

x C

Alexandra Basin Redevelopment Project Environmental Impact Statement

IBE0807/EIS01 9-1 [Final]

9. COASTAL PROCESSES

9.1 GENERAL INTRODUCTION

This Chapter of the Environmental Impact Statement (EIS) examines the impact of the proposed works on the coastal processes of Dublin Bay and provides information about the dispersion and fate of the material lost to the water column during the dredging and disposal operations.

9.2 METHODOLOGY

RPS used a suite of coastal process models based on the MIKE 21 software developed by the Danish Hydraulic Institute (DHI) to address potential coastal processes issues.

In order to quantify the overall impact of the ABR Project, the study utilised a series of model simulations to investigate the following:

The impact of the proposed channel deepening on the tidal regime and inshore wave climate around Dublin Bay;

The stability of the proposed channel deepening and its impact on the sediment transport regime;

The suitability of the existing offshore dredge disposal site as a receptor for the material dredged during the proposed redevelopment;

The fate of the sediment that is dumped at the spoil site; and

The impact of sediment plumes generated during the dredging of Alexandra Basin West and the deepening of the approach channel.

9.3 DATA COLLECTION AND SITE SURVEYS

A thorough historical review of relevant data pertaining to the existing fairway and approach channel at Dublin Port was undertaken to support the assessment of the stability of the existing channel comprising

Collation of maps showing historic changes to the alignment and depth of the channel;

Relevant information associated with previous maintenance dredging campaigns including dredge quantities, type of material, dredging rates and disposal; and

Collation of existing tidal height and tidal current records.



Site surveys were also undertaken comprising

Bathymetric surveys;

Geophysical surveys that were conducted in conjunction with the bathymetric surveys;

Current meter surveys using two acoustic doppler current profilers (ADCPs); and

Sediment sampling, including particle size analyses (PSA).

Site surveys were undertaken by Hydrographic Surveys Ltd during June and July 2013.

The location and coverage of the bathymetric and geophysical survey is shown in Figure 9.1.

Figure 9.1 Location and coverage of the 2013 bathymetric and geophysical survey

Two ADCP current meters were deployed in June 2013 to record current speed, direction and water depth. One meter was located in the harbour channel in close proximity to buoy 16 and the other to the north of approach channel. The current meters were deployed for over one month to record full spring and neap tidal cycles.

This data was complimented by data that was recorded by an ADCP current meter that was deployed 500m west of Burford bank for a previous study undertaken by DHI in relation to a proposed outfall from Ringsend Waste Water Treatment Plant (DHI, 2010). The location of all three ADCPs is shown in Figure 9.2.



Figure 9.2 Deployment locations of ADCP current meters in Dublin Harbour and Dublin Bay

9.4 PROPOSED CHANNEL DESIGN

Dublin Port Company proposes to deepen Alexandra Basin West to achieve depths of -10m Chart Datum (CD). The sediment that is dredged from Alexandra Basin West will be used to infill the basin at Berths 52/53. As part of the development, the fairway and approach channel to Dublin Port will be deepened to increase the ruling depth from -7.8m CD to -10.0m CD. The expected overall capital dredging volume of 6.37million m3 required for the realigned approach channel, harbour channel and Alexandra Basin West have been calculated as approximately:

3.2million m3 of mainly fine sand from the outer approach channel;

2.7million m3of mainly silty material from the inner harbour channel; and

0.47million m3 of mainly silty material from the Alexander Basin West and adjoining channel.

The material to be dredged from the Alexandra Basin West has been shown to be heavily contaminated while some of the material in the channel outside the basin is slightly /moderately contaminated (see chapter 11).



The existing approach channel entering the harbour is partially restricted at the end of the Bull Walls. It can be seen from Figure 9.3 that this restriction forms a slight chicane in the channel at the entrance to the Port and creates navigational difficulties for larger vessels. The design of the new dredged channel includes the realignment of the channel to remove this chicane to provide improved navigational access for larger ships entering the Port. The bathymetry of the existing and proposed approach channel and of Alexandra Basin West pre and post the capital dredging scheme is presented in Figure 9.3 and Figure 9.4 respectively.

Figure 9.3 Existing approach channel bathymetry to Mean Sea Level (MSL)

Figure 9.4 Proposed approach channel bathymetry to Mean Sea Level (MSL)



9.5 MODELIING THE IMPACT OF THE CHANNEL ON COASTAL PROCESSES

Coastal Process Models

The coastal processes were simulated using the coupled MIKE 21 tidal current, wave and sediment transport model, which is a 2D depth averaged model. Bathymetry data for the model was taken from the hydrographic survey conducted in the shipping channel of Dublin Port in 2013 and was supplemented by bathymetric data from the Irish National Seabed Survey (INSS), INFOMAR and other local bathymetric surveys collated by RPS for the Irish Coastal Protection Strategy Study (ICPSS).

The tidal boundaries for the inner Dublin Bay model were taken from the ICPSS tidal surge model. This model was developed using flexible mesh technology with the mesh size (model resolution) varying from circa 24km along the offshore Atlantic boundary to circa 200m around the Irish coastline. The extent and bathymetry of the ICPSS tidal surge model is presented in Figure 9.5. RPS also utilised their ICPSS east coast wave model to gather wave boundary data for the Dublin Bay model to ensure that the hydrodynamic influence of the offshore Kish and Codling banks were accounted for in the model. The extent and bathymetry of the ICPSS east coast wave model is also presented in Figure 9.5.

The Dublin Bay model was developed using flexible mesh technology to provide detailed information on the coastal processes around the harbour and the greater Dublin Bay region. The bathymetry and meshing of the tidal models are presented in Figure 9.6.

Figure 9.5 Extent and bathymetry of the ICPSS tidal surge model (left) and east coast wave model (right)



Figure 9.6 Extent and bathymetry of the Dublin Bay model (left) and the mesh structure of the Dublin Bay model (right)

The Dublin Bay model had mesh sizes varying from 250,000 m2 (equivalent to 500m x 500m squares) at the outer boundary of the model down to a very fine 225 m2 (equivalent to 15m x 15m squares) along the approach channel and around the harbour channel and Alexandra Basin West. All the model bathymetry data sets were set as depth relative to mean sea level to resolve the problem of chart datum varying over the model area.

River flows Mean annual river flows for the Liffey, Dodder and Tolka, as shown in Table 9.1, were used in the modelling of the stability of the approach channel.

Mean winter river flows for the Liffey, Dodder and Tolka, also shown in Table 9.1, were used in the modelling of the dispersion and fate of sediment plumes arising from the capital dredging works since the dredging works are to be restricted to the winter months only.

Table 9.1 River Flows from the Liffey, Dodder and Tolka used in the coastal process models

Source

Mean annual discharge rate

(m3/s) Mean winter discharge rate

(m3/s)

Liffey 15.6 25.0 Dodder 2.3 2.6 Tolka 1.4 1.6



9.6 THE IMPACT OF THE PROPOSED CAPITAL DREDGING SCHEME ON THE TIDAL REGIME

The Mike 21 Hydro Dynamic (HD) model was used to simulate the existing tidal regime in Dublin Bay, including the fairway, approach channel and berths of Dublin Port. Typical tidal flow patterns for a spring ebb tide are presented in Figure 9.7 and for a spring flood tide in Figure 9.8.

The model of the existing tidal regime was calibrated using tidal height data and current data from the deployed ADCP current meters to ensure that the model results were representative of actual conditions (see Appendix 9).

To assess the impact of the proposed capital dredging scheme, the bathymetry of the existing tidal model was altered to include the capital dredging of the fairway, approach channel and Alexandra Basin West and the infilling of the Berth 52/53 basin. Comparisons of the hydrodynamic regime under normal spring tidal conditions with that of the existing tidal flow regime were then made to quantify the impact of the proposed capital dredging scheme.

The predicted typical spring ebb and flood flow regimes post the capital dredging scheme is presented in Figure 9.9 and Figure 9.10 for spring ebb and spring flood regimes respectively.

The difference in the mid spring ebb and flood current velocities between the simulation with the existing and post capital dredging scheme bathymetries are presented in Figure 9.11 and Figure 9.12 respectively. These plots represent the differences in flow velocities during spring mid ebb and spring mid flood tidal conditions. It can be seen that the changes in the tidal flow velocities between the existing and proposed channel configurations are not significant outside the immediate vicinity of the channel.

The differences in the mean current velocity over the full ebb and flood tides are presented in Figure 9.13 and Figure 9.14 respectively. These figures show that the proposed capital dredging scheme will cause no significant change to the tidal regime outside the immediate vicinity of the proposed works.

It can therefore be concluded that the proposed capital dredging works will have no impact on the tidal regime in the greater Dublin Bay area outside the immediate vicinity of the approach channel.

Within the approach channel, the tidal regime will perform in the same manner. The only change occurs where the channel has been realigned. There will be no perceptible change in the tidal velocity within the channel or in its power to cause scouring of the seabed.



Figure 9.7 Typical spring ebb flow pattern – Existing Port Channel

Figure 9.8 Typical spring flood flow pattern - Existing Port Channel



Figure 9.9 Typical spring ebb flow pattern – Post Capital Dredging Scheme

Figure 9.10 Typical spring flood flow pattern - Post Capital Dredging Scheme



Figure 9.11 Difference in mid spring ebb current velocity as a result of the proposed capital dredging scheme

Figure 9.12 Difference in mid spring flood current velocity as a result of the proposed capital dredging scheme



Figure 9.13 Difference in the mean spring ebb current velocity as a result of the proposed capital dredging scheme

Figure 9.14 Difference in the mean spring flood current velocity as a result of the proposed capital dredging scheme



9.7 THE IMPACT OF THE PROPOSED CAPITAL DREDGING SCHEME ON THE WAVE CLIMATE

The hydrodynamic regime around Dublin Port and its approach channel can be influenced by waves generated within in the greater Dublin Bay area and the Irish Sea. An assessment was undertaken to determine the impact of the proposed capital dredging scheme on the wave climate.

For the modelling exercise, the inshore wave climate around the Port and the greater Dublin Bay area was established by transforming offshore waves into Dublin Port using the Mike 21 Spectral Wave (SW) modelling module. This is a spectral wave module that describes the propagation, growth and decay of waves in near-shore areas and takes account of the effects of refraction, shoaling, local wind generation and energy dissipation due to bottom friction and wave breaking.

The offshore wave data for points at 5.66oW, 55.50oN and 5.66oW, 55.25oN was taken from the UK Met Office European wave model for the period 1989-2004 and used as a source to select the largest event for each of the north east, east and south east directions. The three hourly data included wind wave and swell wave components in the form of the significant wave height Hmo, mean wave period Tm and mean wave directions. The offshore wave climate data used in the wave transformation simulations are presented in Table 9.2.

Table 9.2 Offshore wave climate data used to simulate the inshore wave climate

Significant wave height (m)

Peak wave period (s)

Mean wave direction (oN)

North Easterly event 4.6 8.9 29

Easterly event 4.1 8.8 98

South Easterly event 5.4 10.4 148

The inshore wave climate at Dublin Bay was established by transforming these offshore wave conditions to Dublin Bay for the north easterly, easterly and south easterly storm events. This was undertaken using both the existing bathymetry of the fairway, approach channel and Dublin Port berths and the proposed bathymetry post the capital dredging scheme.

Figure 9.15 to Figure 9.20 show the inshore wave heights in Dublin Bay at spring high tide during north easterly, easterly and south easterly storm events pre and post the proposed capital dredging scheme.

Wave height difference plots are presented for the three storm events in Figure 9.21 to Figure 9.23 to highlight changes to the inshore wave climate as a result of the capital dredging scheme. The results show that there are no significant differences in the wave heights outside the immediate vicinity of the approach channel for each of the storm events. Similar results were observed in the wave climate simulations run at mid and low tide levels.

It can therefore be concluded that the proposed capital dredging works will have no impact on the wave climate in the either the approach channel or in the greater Dublin Bay area outside the immediate vicinity of the approach channel.



Figure 9.15 North Easterly storm wave heights at spring high water – Existing Port Channel

Figure 9.16 North Easterly storm wave heights at spring high water – Post Capital Dredging Scheme



Figure 9.17 Easterly storm wave heights at spring high water – Existing Port Channel

Figure 9.18 Easterly storm wave heights at spring high water – Post Capital Dredging Scheme



Figure 9.19 South Easterly storm wave heights at spring high water – Existing Port Channel

Figure 9.20 South Easterly storm wave heights at spring high water – Post Capital Dredging Scheme



Figure 9.21 North Easterly Storm - Difference in significant wave heights at spring high water as a result of the proposed capital dredging scheme

Figure 9.22 Easterly Storm - Difference in significant wave heights at spring high water as a result of the proposed capital dredging scheme



Figure 9.23 South Easterly Storm - Difference in significant wave heights at spring high water as a result of the proposed capital dredging scheme

9.8 THE IMPACT OF THE PROPOSED CAPITAL DREDGING SCHEME ON THE SEDIMENT TRANSPORT REGIME AND MORPHOLOGICAL STABILITY OF THE CHANNEL

9.8.1 Review of previous maintenance dredging campaigns

A series of digital bathymetric surveys of the approach channel were available from Dublin Port records. The surveys were undertaken in association with maintenance dredging campaigns covering the periods:

2007 to 2008

2008 to 2009

2009 to 2010

2011 to mid 2012

Mid 2012 to late 2012

Each of the above-mentioned surveys were input to a Geographical Information System (GIS) and overlain to determine changes in dredged depth and areas of accretion.



During the period from December 2007 to January 2008, maintenance dredging operations were undertaken to restore the depths in the harbour channel and to remove material which had encroached along the north side of the approach channel as shown in Figure 9.24. The amount of material removed from the harbour and approach channel during this survey was circa 0.41million m3.

Figure 9.24 Change in the depth of the approach channel between December 2007 and

January 2008 (including maintenance dredging)

From March 2009 to March 2010 there was a general accretion of sediment in the approach channel. The accretion is most notable along the northern edge of the approach channel seaward of the Bull Wall and along the side slopes of the channel landward of the Bull Wall. The net increase in sedimentation of the approach channel was 0.181million m3 during this one year period (see Figure 9.25).

Figure 9.25 Change in the depth of the approach channel between March 2009 and March 2010 (no maintenance dredging)



From September 2011 to July 2012, some 0.218million m3 of sediment was removed from the approach channel as part of routine maintenance dredging operations that were conducted to remove sediment that had accreted in the channel during the preceding period as shown on Figure 9.26. The dredging operations removed sediment from along the south and north side slopes of the channel landward of the Bull Wall and from the north side of the approach channel seaward of the Bull Wall. It should be noted that some 0.65million m3 of material was removed from the whole of the harbour area during this period but much of this material was from parts of the harbour not covered by this comparative study.

Figure 9.26 Change in the depth of the approach channel between September 2011 and July 2012 (including maintenance dredging)

The review of previous maintenance dredging campaigns has identified the following:

There is a consistent tendency for sediment to become deposited along the north side of the approach channel from the end of the North Bull Wall towards Buoy No. 3; and

There is a tendency for the width of the approach channel landward of the Bull Walls to decrease over time. This is most likely to be a direct result of the deposition of sediment from fluvial sources, coupled with the hydrodynamic influence of manoeuvring ships.



9.8.2 Model Simulations

Morphological model simulations were used to assess the impact of the capital dredging scheme on the sediment transport regime and the stability of the existing and proposed approach channel. The simulations took account of tides, waves, sediment transport and morphological changes to the seabed during extreme storm events from the North Easterly, Easterly and South Easterly sectors.

It is during these extreme storm events that the approach channel is exposed to the most arduous hydrodynamic conditions and is most susceptible to infilling.

In the morphological model simulations, the sea bed bathymetry was updated every 15 minutes in response to the effect of tides, waves and sediment transport. The changes in bathymetry were automatically included in the hydrodynamic and spectral wave simulations to ensure the morphological changes were accurately modelled throughout each storm event.

The storm events were established by examining 15 years of three hourly wind and wave data for the period 1989 to 2004 provided by the UK Met Office and selecting the largest event for each of the North Easterly, Easterly and South Easterly sectors. To produce the most arduous conditions, the storms were run over a period which included large spring tides, with the peak of the storm coinciding with the maximum spring tide.

The stability of the channel was assessed by calculating the change in the morphological response of the sea bed level over the course of the storm event. In addition to this, a comparison was made of the morphological changes in the bathymetry of Dublin Bay between the existing approach channel and the proposed approach channel for each storm event to determine if the proposed capital dredging scheme would have a significant impact on the sediment transport regime of the area.

North Easterly storm event

As the North Easterly storm event had a duration of only 4.5 days, the event was simulated with a morphological speed up factor of 2, so that the morphological changes equated to a nine day storm. The offshore wave heights, wave periods and tidal regime during this event are presented in Figure 9.27.

By comparing Figure 9.28 and Figure 9.29 which presents the change in the sea bed level after the North Easterly storm event for the existing and proposed approach channel respectively, it will be seen that the morphological response of the sea bed to the storm has a similar pattern pre and post the proposed capital dredging scheme.

Figure 9.30 presents the difference in sea bed level change between the existing and proposed channel during this storm event. It will be seen from this diagram that the proposed new channel does not result in any significant change in the morphological response of the sea bed in Dublin Bay outside the channel area during a North Easterly storm.



Figure 9.27 Morphological model simulation input data for a North Easterly storm event - Offshore wave height and period (upper diagram) and tidal regime (lower diagram)

Figure 9.28 Change in bed levels after a North Easterly storm event – Existing Port Channel



Figure 9.29 Change in bed levels after a North Easterly storm event - Post Capital

Dredging Scheme

Figure 9.30 Difference in bed level change as a result of the proposed capital dredging scheme - North Easterly storm event



Easterly storm event

The Easterly storm event was simulated using the morphological model over a period of eight days for both the existing and proposed approach channel. The offshore wave heights, wave periods and tidal regime during this event are presented in Figure 9.31.

By comparing Figure 9.32 and Figure 9.33 which presents the change in the sea bed level after the Easterly storm event for the existing and proposed approach channel respectively, it will be seen that the morphological response of the sea bed to the storm has a similar pattern pre and post the proposed capital dredging scheme. Figure 9.34 presents the difference in sea bed level change between the existing and proposed channel during this storm event. It will be seen from this diagram that the proposed new channel does not result in any significant change in the morphological response of the sea bed in Dublin Bay outside the channel area during an Easterly storm.

Figure 9.31 Morphological model simulation input data for an Easterly storm event - Offshore wave height and period (upper diagram) and tidal regime (lower diagram)



Figure 9.32 Change in bed levels after an Easterly storm event – Existing Port Channel

Figure 9.33 Change in bed levels after an Easterly storm event - Post Capital Dredging Scheme



Figure 9.34 Difference in bed level change as a result of the proposed capital dredging scheme - Easterly storm event

South easterly storm event

The South Easterly storm event was the most energetic of all three of storms simulated with the offshore wave heights exceeding 4.5m on several instances. The morphological model simulated a ten day storm event for both the existing and proposed approach channels, the offshore wave heights, wave periods and tidal regime during the event are presented in Figure 9.35.

By comparing Figure 9.36 and Figure 9.37 which presents the change in the sea bed level after the South Easterly storm event for the existing and proposed approach channel respectively, it will be seen that the morphological response of the sea bed to the storm has a similar pattern pre and post the proposed capital dredging scheme. Figure 9.38 presents the difference in sea bed level change between the existing and proposed channel during this storm event. It will be seen from this diagram that the proposed new channel does not result in any significant change in the morphological response of the sea bed in Dublin Bay outside the channel area during a South Easterly storm.



Figure 9.35 Morphological model simulation input data for a South Easterly storm event - Offshore wave height and period (upper diagram) and tidal regime (lower diagram)

Figure 9.36 Change in bed levels after a South Easterly storm event – Existing Port Channel



Figure 9.37 Change in bed levels after a South Easterly storm event - Post Capital Dredging Scheme

Figure 9.38 Difference in bed level change as a result of the proposed capital dredging scheme – South Easterly storm event



The results from the morphological simulations of the existing and proposed approach channel show that the proposed channel will perform in a similar manner to the existing channel. As with the existing channel there will be a tendency for the northern bank of the approach channel, seaward of the North Bull Wall, to migrate south under storm conditions. Similarly it is expected that there will be siltation along the banks of the approach channel landward of the Bull Walls with a tendency for these banks to migrate in towards the channel. It is expected that the new channel will require maintenance dredging of a similar magnitude to that required with the existing channel.

Overall, the results show that there will be no significant impact on the sediment transport regime within the River Liffey Channel, Tolka Estuary or Dublin Bay as a result of the capital dredging scheme.

9.9 DREDGING ACTIVITY AND DISPOSAL OF DREDGE MATERIAL

9.9.1 Summary of works

Capital Dredging within Alexandra Basin West

The redevelopment of Alexandra Basin West will include the construction of new quays and jetties and capital dredging to deepen the basin to -10m CD (further detail is contained in Chapter 4).

The dredging will involve removal of circa 0.47 million m3 of mainly silty material from Alexander Basin West. A programme of sediment quality sampling and analysis has shown that the sediments within Alexandra Basin West are contaminated and not suitable for disposal at sea (see Chapter 11).

The dredged material recovered from Alexandra Basin West will be treated and transported by barge to a treatment facility adjacent to Berth 52/53. It will be stabilised and modified to improve the engineering properties of the material, to allow its re-use as fill material for reclamation works identified within the Port. This process is explained in more detail in Chapter 4.

The dredging will be undertaken using a floating pontoon with an excavator mounted clamshell bucket adapted for environmental dredging. This will minimise the disturbance and escape of material at the seabed and during removal through the water column. A silt curtain will also be utilised around the dredger whilst the dredging of contaminated material is ongoing.

Capital dredging of the Approach Channel

The ABR Project requires capital dredging of the navigation channel to a level of -10m CD, extending from the North Wall Quay Extension (downstream of the East Link Bridge) to the Dublin Bay Buoy. This equates to circa 5.9 million m3 of dredging (excluding the 0.47 million m3 to be dredged from Alexandra Basin West).

In order to negate any potential impact of the channel dredging on Poolbeg Marina, it is proposed to construct a marina wall along the edge of navigation channel at Poolbeg Marina as described in Chapter 4.



The sediment quality of the material to be dredged within the navigation channel has been tested for contamination and is suitable for disposal at sea, however, some of the material to be dredged from the channel outside Alexandra Basin West has shown slight/moderate levels of contamination (see chapter 11).

It is envisaged that the dredging of uncontaminated material will be carried out during winter months only (October to March) to negate any potential impact on salmonid mitigation (particularly smolts) and summer bird feeding, notably terns, in the vicinity of the dredging operations.

Dredging of slight/moderately contaminated silty material adjacent to the North Wall Quay Extension and the entrance to Alexandra Basin West will be undertaken in conjunction with the dredging of gravels from the main channel. The slight/moderately contaminated silts deposited at the dump site will be overlaid (capped) with the dredged gravels.

To suit the project programme, the dredging operations will generally be undertaken starting at the outer area of the channel and progressing inwards towards the harbour channel using a trailer suction dredger or equivalent. The dredged material will be loaded into barges and transported directly to a licensed sea disposal site located at the entrance to Dublin Bay.

9.9.2 Proposed disposal site of dredge material at sea

As outlined in the summary of works above, it is intended to dispose of the dredge material arising from the approach channel at a licensed sea disposal site (subject to the granting of a Dumping at Sea Permit by the EPA). The closest and preferred site is to the west of the Burford Bank as presented in Figure 9.39.

Figure 9.39 Location of the licensed dredged spoil disposal site



This disposal option is preferred because it keeps the dredge material within the natural Dublin Bay sediment cell.

Other disposal options were considered including beneficial reuse of the material such as material for beach re-nourishment, particularly at sites where erosion is taking place along the northern shoreline of Dublin Bay. Unfortunately the grading of the sand to be dredged was too fine to be suitable for this type of use. No other alternative use was identified which out-weighed the suitability of the disposal at sea option.

9.9.3 Assessment of the fate and dispersion of dredge spoil at the licensed offshore disposal site

A series of computational model simulations were undertaken to assess the dispersion and fate of the dredged material which is to be disposed of at the licensed offshore disposal site to the west of the Burford Bank.

The particle size distribution analysis of the sediment samples detailed in Appendix 11 shows that are essentially two different types of material that make up the sea bed of the navigation channel. The material in the sea bed of the navigation channel, seaward of the Bull Walls, is generally composed of afine sand whilst the material in the sea bed, landward of the Bull Walls, is generally composed of a fine silty material and a small proportion of coarser silt.

The results of the geophysical surveys show that rock is not expected to be encountered by the capital dredging activities required to achieve the design dredged depth of -10.0m CD.

Model simulations

The disposal operations at the licensed offshore disposal site were simulated using a Mike 21 sediment transport model that was coupled with the Mike 21 hydrodynamic module.

It was assumed that the volume of dredging would be spread relatively evenly over a six year period with an average volume of circa 0.177million m3 dredged per month. It was also assumed that the dredging would be undertaken on a 24/7 basis with barges disposing of the material over the dump site on a regular basis throughout each winter dredging campaign.

The model simulations were run for the disposal of the dredged material over the course of a complete lunar month, which includes the full range of spring and neap tidal flow conditions. The results were then extrapolated to estimate the deposition of both fine sand and silt over a full six month winter dredging campaign.

The deposition of the silt and fine sand fractions were modelled separately.

The deposition of silt at the licensed offshore disposal site

The characteristics of the silt modelled in the sediment transport simulation were determined from the Particle Size Distributions (PSDs) of the sediment samples collected in the harbour channel (see Chapter 11 and Appendix 11). In the model simulations, the sediment material was characterised by three discrete fractions with mean diameters of 200µm, 20µm and 3µm, with each fraction constituting 1/3 of the total volume of silt to be dredged.



The spill rate from the barges was taken to be 108kg ms-1, this equates to the disposal of circa 0.177million m3 per month. The coupled Mike21 sediment transport model was then used to simulate the fate of the silt released from the barges over the dump site by moving a sediment source along the track that the barge would take as it transverses the dump site area during the disposal operation. The model then simulated the dispersion settlement and re-erosion of each fraction of the silt in response to the tidal currents throughout the model area.

The coarser fraction of the silt, i.e. the sand fraction that had a mean grain size of 200µm was found to behave differently relative to the two finer fractions that had mean grain diameters of 20µm and 3µm. The sand fraction remained on the dump site, whereas the two finer silt fractions were carried away by the tidal currents.

The predicted deposition of the silt fractions of the dredged material within Dublin Bay at the end of the six month dredging campaign is presented in Figure 9.40. This Figure shows that only a very small amount of silt is deposited, resulting in a maximum sea bed level increase of less than 0.3µm. Thus, it can be concluded that the deposition site is fully dispersive for the silt fraction of the dredged material.

The impact of the silt dispersion on the suspended sediment concentration is shown by a series of plume diagrams, Figure 9.41 to Figure 9.48, taken from the silt dispersion simulation at times of high water, mid ebb, low water and mid flood at both spring and neap tides. It will be seen from these suspended sediment concentration plumes that apart from the area around the dump barge the sediment concentrations will remain below 20 mg/litre above back ground.



Figure 9.40 Total silt deposition after six months of continuous disposal of silt spoil material



Figure 9.41 Suspended sediment concentration plume at times of high water neaps

Figure 9.42 Suspended sediment concentration plume at times of mid ebb neaps



Figure 9.43 Suspended sediment concentration plume at times of low water neaps

Figure 9.44 Suspended sediment concentration plume at times of mid flood neaps



Figure 9.45 Suspended sediment concentration plume at times of high water springs

Figure 9.46 Suspended sediment concentration plume at times of mid ebb springs



Figure 9.47 Suspended sediment concentration plume at times of low water springs

Figure 9.48 Suspended sediment concentration plume at times of mid flood springs



The deposition of sand at the licensed offshore disposal site

The characteristics of the sand modelled in the sediment transport simulation were determined from the sediment sampling survey described in Appendix 11. In the model simulations the sand material was defined by three discrete fractions, with mean grain diameters of 200µm, 100µm and 60µm. The percentage of the material was 20%, 60% and 20% for the 200µm, 100µm and 60µm fractions respectively. The spill rate from the barges depositing material at the dump site was 108kg/s-1, which is equivalent to the disposal of 0.177million m3 of dredging spoil per month.

The deposition of the sand on the disposal site after six months of dredging is shown in Figure 9.49. This Figure indicates that unlike the silt, virtually all of the sand sediment that was released from the barges over the spoil site is predicted to stay on the spoil site.

Figure 9.49 Total sand deposition after six months of continuous disposal of sand spoil material

The mean predicted suspended sediment concentration (SSC) of the sand fraction envelop is presented in Figure 9.50. The mean SSC envelop shows the mean concentration in every cell of the model which occur during the simulation. This Figure shows that the predicted suspended sediment concentrations during the disposal of the dredged sand material outside the immediate area of the disposal site are very low, with mean values of less than 0.02mg/l. Thus virtually all of the sand deposited on the dump site will remain on the site under normal tidal conditions.



Figure 9.50 Mean suspended sediment concentration during the disposal of sand spoil material

Movement of sand at the disposal site under storm conditions

Whilst the sand deposited on the dump site is not re-suspended by normal tidal action, it is expected that movement of the bed in this area will occur during storm events.

To assess the influence of storm events on the re-distribution of deposited sand at the spoil site, the movement of the sandy fraction of the dredged material at the spoil site during a South Easterly storm was simulated. This was undertaken using the coupled tide, wave and sediment transport model. The storm selected was that used for the channel stability simulation and details of the storm event are given in Figure 9.35. In order to be able to demonstrate the movement of the deposited sand on the disposal site, the remainder of the bed in the Dublin Bay model was fixed. In reality, the bed of the bay which is also sand will move under these same conditions.

This bed load transport of the sand during the ten day South Easterly storm is shown in Figure 9.51. This Figure shows the movement of sand from the disposal site at the end of the simulation. It shows that sand has moved away from the site and that sand waves have formed on the north eastern part of the site. These sand waves are similar to the sand waves that were observed in the hydrodynamic surveys of this area.



During the storm, circa 20% of the sand has been removed from the disposal site, indicating that gradually through time, the sand deposited on the site will be assimilated into the general sedimentary budget of the Bay and thus the sand will not be lost to the overall coastal processes of the greater Dublin Bay area.

Figure 9.51 Transport of the sand material from the spoil site at end of 10 day South Easterly storm event

Comparison of model predictions with previous dredging records

In 2008, a hydrographic survey of the disposal site was conducted and repeated again in 2013 after the spoil material that had been dredged from the approach channel during routine maintenance operations was dumped at the spoil site. These surveys were compared to determine how much the sea bed level changed as a result of the dredging campaign. Over the course of the maintenance operations, approximately 0.650million m3 of sediment was dumped within one segment of the spoil site. However, an assessment of the 2008 and 2013 hydrographic surveys indicated that the change in sea bed level equated to only an additional 0.075million m3 of sediment at this segment of the spoil site, whilst the change in sea bed level over the entire spoil site equated to an additional 0.094million m3 of sediment.

The maintenance dredging undertaken in 2012 included some 0.553million m3 of silts from the berths and the inner channel and 0.097million m3 of sandy material from the outer channel. Thus only about 15% of the quantity was sand material.

The data therefore indicated that a large proportion of the sediment that was dumped at the spoil site did not actually settle to the seabed but was instead dispersed and in addition some



of the material that did settle on the site has spread into the adjoining seabed area. This is consistent with the results of the model simulations indicating that the modelling is capable of reproducing the fate and dispersion of dredged spoil dumping. The survey of the existing dump site in 2013 also showed that the piles of partially contaminated material covered by the coarse material were still present on the site.

9.9.4 Assessment of the fate and dispersion of dredging plumes during the capital dredging scheme

The impact of the dredging plumes in Alexandra Basin West and the Liffey channel in the harbour

The dredging of Alexandra Basin West will be undertaken using specially adapted techniques as described in Chapter 4 to reduce the spread of contaminated material during the dredging operation. Thus there will be no significant loss of contaminated sediment to the water column from the dredging of Alexandra Basin West itself.

Simulations were undertaken to determine the concentration and distribution of sediment lost to the water column during the dredging operation in the Liffey channel in the harbour. The material to be dredged from the harbour channel is predominantly silt. As with the silt disposal modelling, the sediment material was characterised by three discrete fractions with mean diameters of 200µm, 20µm and 3µm. In the channel adjacent to the Alexandra Basin West each fraction constituted 1/3 of the total volume of silt to be dredged. In the outer parts of the Liffey channel in the harbour the sand fraction consisted about half of the total volume to be dredged. The coarser fraction of the silt, i.e. the sand fraction that had a mean grain size of 200µm was found to behave differently relative to the two finer fractions that had mean grain diameters of 20µm and 3µm. The sand fraction remained in the area of the dredging and produced virtually no plume, whereas the two finer silt fractions were carried away by the tidal currents. Thus the plume modelling was undertaken for the silt fractions with the silt losses being taken as 1% at the dredger head and 1% for the overspill at the surface.

The Liffey channel in the harbour is an area which is influenced by the fresh water river inflows and the temperature gradients from the three power station cooling water systems. Stratification of the water column takes place at certain time of the tide in Liffey channel particularly in the central section of the harbour. Therefore the simulations were undertaken using the integrated 3D Mike 3fm hydrodynamic and mud transport model which includes temperature and salinity effects. The Tolka, Liffey and Dodder river flows were taken as the winter average flows (Table 9.1). The power station flow and temperature characteristics used in the model are shown in Table 9.3.

Table 9.3 Power Station discharge and temperature characteristics, Dublin Harbour

Plant

Discharge m3/s ∆T degree C Outlet Intake

North Wall 3.9 10

Surface layer Mid depth

Synergen 7.6 6.6 Surface layer Mid depth Poolbeg 18.7 7.1 Surface layer Surface Layer



The extent and bathymetry of the 3D model, which had five vertical layers, is shown in Figure 9.52. The boundary conditions for the 3D model were taken from the results of the main Dublin Bay hydrodynamic model shown in Figure 9.6. The area of the Liffey channel in the 3D model is shown in more detail in Figure 9.53.

Figure 9.52 Extent and bathymetry of the 3D Dublin Port model

Figure 9.53 Bathymetry of harbour area of 3D model of proposed development



The dredging of the inner harbour channel will be undertaken over three separate six month winter periods. The modelling was therefore undertaken for dredging operations in the outer, middle and inner sections of the harbour channel.

Dredging of outer section of the Liffey channel in the harbour

The predicted deposition of the silt fractions lost to the water column during the dredging of the outer section of the Liffey channel in the harbour at the end of the six month dredging campaign is presented in Figure 9.54 This Figure shows that only an imperceptible amount of silt is deposited, resulting in a maximum deposition depth of less than 0.1µm. Thus, it can be concluded that the silt lost to the water column during the dredging of the outer section of the Liffey channel in the harbour will be widely dispersed within the Irish Sea.

The impact of the silt dispersion on the suspended sediment concentration is shown by a series of plume diagrams, Figure 9.55 to Figure 9.58, taken from the silt dispersion simulation at times of low water, mid flood, high water and mid ebb at the time during the dredging operation when the suspended sediment concentrations in the Tolka estuary were at their highest values. It will be seen from these suspended sediment concentration plumes that apart from the area around the dredger itself, the sediment concentrations will peak at about 25 mg/l above background and the mean value over the whole of the dredging period will be less than about 10 mg/l above background.

Figure 9.54 Total silt deposition after six months of dredging of the outer section of the Liffey channel in the harbour



Figure 9.55 Suspended sediment concentration plume at time of low water

Figure 9.56 Suspended sediment concentration plume at time of mid flood



Figure 9.57 Suspended sediment concentration plume at time of high water

Figure 9.58 Suspended sediment concentration plume at time of mid ebb



Dredging of middle section of the Liffey channel in the harbour

The predicted deposition of the silt fractions lost to the water column during the dredging of the middle section of the Liffey channel in the harbour at the end of the six month dredging campaign is presented in Figure 9.59. This Figure shows that only an imperceptible amount of silt is deposited outside the harbour channel resulting in a maximum deposition depth of less than 0.2µm. Thus, it can be concluded that the silt lost to the water column during the dredging of the middle section of the Liffey channel in the harbour will be will be widely dispersed within the Irish Sea.

The impact of the silt dispersion on the suspended sediment concentration is shown by a series of plume diagrams, Figure 9.60 to Figure 9.63, taken from the silt dispersion simulation at times of low water, mid flood, high water and mid ebb at the time during the dredging operation when the suspended sediment concentrations in the Tolka estuary were at their highest values. It will be seen from these suspended sediment concentration plumes that apart from the area around the dredger itself, the sediment concentrations will peak at about 30 mg/litre above background and the mean value over the whole of the dredging period will be less than 16 mg/l above background.

Figure 9.59 Total silt deposition after six months of dredging of the middle section of the Liffey channel in the harbour



Dredging of inner section of the Liffey channel in the harbour

The predicted deposition of the silt fractions lost to the water column during the dredging of the inner section of the Liffey channel in the harbour at the end of the six month dredging campaign is presented in Figure 9.64. This Figure shows that an imperceptible amount of silt is deposited outside the harbour channel harbour basins resulting in a maximum deposition depth of less than 0.05µm. Thus, it can be concluded that the silt lost to the water column during the dredging of the inner section of the Liffey channel in the harbour will be almost entirely contained within the harbour area.

The impact of the silt dispersion on the suspended sediment concentration is shown by a series of plume diagrams, Figure 9.65 to Figure 9.68, taken from the silt dispersion simulation at times of low water, mid flood, high water and mid ebb at the time during the dredging operation when the suspended sediment concentrations in the Tolka estuary were at their highest values. It will be seen from these suspended sediment concentration plumes that apart from the area in the harbour channel and basins, the sediment concentrations will peak at about 26 mg/l above background and the mean value over the whole of the dredging period will be less than about 18 mg/litre above background.

Figure 9.64 Total silt deposition after six months of dredging of the inner section of the Liffey channel in the harbour



Impact of harbour channel dredging on power station cooling water systems

The suspended sediment concentration at the various power station cooling water inlets has been extracted from each of the three dredging campaigns. The peak and mean increase in the suspended sediment concentrations predicted by the 3D model simulations are as given in Table 9.4 :

Table 9.4 Peak and mean suspended sediment concentrations at various power station cooling inlets

Cooling water intake

Dredging Location Peak Concentration

(mg/litre) Average Concentration

(mg/litre)

Poolbeg power station

Inner channel 30 18

Middle channel 23 14

Outer 16 8

Synergen power station

Inner channel 35 23


Outer 14 7

North Wall station

Inner channel 50 30


Outer 10 5

It will be seen from the results of the simulations that the levels of additional suspended sediment concentrations at the power station intakes is relatively small and is unlikely to have a significant effect on the power station operations.

9.10 CONCLUSIONS

An extensive programme of model simulations, supported by fieldwork and literature review, has been undertaken to evaluate how the proposed ABR Project would impact the coastal processes and the stability of the approach channel as well as to investigate the disposal of dredged spoil at the existing licensed offshore spoil site within Dublin Bay.

This programme included:

Fieldwork comprising hydrographic surveys, geophysical surveys, sediment sampling and analysis and tidal current surveys;

Review of previous maintenance dredging campaigns;

Model simulations of the Spring and Neap tidal flow regime;

Model simulations of the wave climate under a range of storm conditions;

Model simulations of the sediment transport regime;



Morphological simulations combining the results of tidal flow, storm waves and sediment transport;

Model simulations of the dispersion, fate and settlement of dredge spoil dumped at the licensed offshore disposal site located close to the Burford Bank; and

Model simulations of the dispersion, fate and settlement of dredge spoil released to the water environment during dredging operations; and

Use of 3D modelling within the inner harbour to take into account the presence of salinity gradients within the water column (salt wedge) of the Liffey Channel.

The computational modelling was undertaken using RPS's in-house suite of MIKE coastal process modelling software developed by the Danish Hydraulic Institute (DHI). The models were calibrated using the results of the fieldwork and other data held by RPS.

These models are currently being used to inform the Irish National Coastal Protection Strategy being developed by RPS on behalf of the OPW. The models are also currently being run on a 24/7 basis to support the OPW Storm Surge Forecasting Programme. The models provide predictions of extreme tide and storm surge levels along the eastern coastline of Ireland which are provided to the Local Authorities in order to provide early warning of potential coastal flood events.

The results of the model simulations show that:

There will be no significant change to the tidal flow regime of Dublin Bay;

There will be no significant change to the wave climate within Dublin Bay;

There will be no perceptible change in the tidal velocity within the deepened, realigned navigation channel or in its power to cause scouring of the sea bed;

The new navigation channel will require maintenance dredging of a similar magnitude to that required with the existing channel;

There will be no significant change to the sediment transport regime within Dublin Bay, including the Tolka Estuary;

The proposed offshore disposal site to the west of the Burford Bank is dispersive for the silt fractions within the dredged spoil material. The sand fractions within the dredged spoil will remain on the disposal site under normal tidal conditions. However under storm conditions the sand will gradually be assimilated into the overall sediment regime of Dublin Bay.

The existing disposal site at the Burford Bank is the preferred disposal option as the fine sand material from the navigation channel will not be lost to the overall sediment supply to Dublin Bay;



Model simulations of the dispersion, fate and deposition of sediment plumes arising from the dredging and disposal operations have been used to inform the environmental assessment of the natural environment (Chapter 5 and Habitats Directive Assessment, Natura Impact Statement) and the water environment (Chapter 10).

Restricting the navigation channel dredging operations to the winter months (October to March) provides suitable mitigation to ensure that the dredging operations will have no significant impact on the qualifying interests of Natura 2000 sites.

The dispersion, fate and deposition of sediment plumes arising from the dredging and disposal operations not expected to impact on other users of the waters within the River Liffey channel or Dublin Bay.

Residual Impacts

The comprehensive studies undertaken, as outlined above, show that ABR Project is not expected to have a significant detrimental impact on the coastal processes of Dublin Bay. It can therefore be concluded that the proposed works will have no residual impact.


NPWS Site Synopses

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SITE NAME: NORTH DUBLIN BAY SAC SITE CODE: 000206 This site covers the inner part of north Dublin Bay, the seaward boundary extending from the Bull Wall lighthouse across to the Martello Tower at Howth Head. The North Bull Island is the focal point of this site. The island is a sandy spit which formed after the building of the South Wall and Bull Wall in the 18th and 19th centuries. It now extends for about 5 km in length and is up to 1 km wide in places. A well-developed and dynamic dune system stretches along the seaward side of the island. Various types of dunes occur, from fixed dune grassland to pioneer communities on foredunes. Marram Grass (Ammophila arenaria) is dominant on the outer dune ridges, with Lyme Grass (Leymus arenarius) and Sea Couchgrass (Elymus farctus) on the foredunes. Behind the first dune ridge, plant diversity increases with the appearance of such species as Wild Pansy (Viola tricolor), Kidney Vetch (Anthyllis vulneraria), Bird's-foot Trefoil (Lotus corniculatus), Rest Harrow (Ononis repens), Yellow Rattle (Rhinanthus minor) and Pyramidal Orchid (Anacamptis pyramidalis). In these grassy areas and slacks, the scarce Bee Orchid (Ophrys apifera) occurs. About 1 km from the tip of the island, a large dune slack with a rich flora occurs, usually referred to as the 'Alder Marsh' because of the presence of Alder trees (Alnus spp). The water table is very near the surface and is only slightly brackish. Saltmars Rush (Juncus maritimus) is the dominant species, with Meadow Sweet (Filipendula ulmaria) and Devil's-bit (Succisa pratensis) being frequent. The orchid flora is notable and includes Marsh Helleborine (Epipactis palustris), Common Twayblade (Listera ovata), Autumn Lady's-tresses (Spiranthes spiralis) and Marsh orchids (Dactylorhiza spp.) Saltmarsh extends along the length of the landward side of the island. The edge of the marsh is marked by an eroding edge which varies from 20 cm to 60 cm high. The marsh can be zoned into different levels according to the vegetation types present. On the lower marsh, Glasswort (Salicornia europaea), Saltmarsh Grass (Puccinellia maritima), Annual Sea-blite (Suaeda maritima) and Greater Sea-spurrey (Spergularia media) are the main species. Higher up in the middle marsh Sea Plantain (Plantago maritima), Sea Aster (Aster tripolium), Sea Arrowgrass (Triglochin maritima) and Sea Pink (Armeria maritima) appear. Above the mark of the normal high tide, species such as Scurvy Grass (Cochlearia officinalis) and Sea Milkwort (Glaux maritima) are found, while on the extreme upper marsh, Sea Rushes (Juncus maritimus and J. gerardii) are dominant. Towards the tip of the island, the saltmarsh grades naturally into fixed dune vegetation. The island shelters two intertidal lagoons which are divided by a solid causeway. The sediments of the lagoons are mainly sands with a small and varying mixture of silt andclay. The north lagoon has an area known as the "Salicornia flat", which is dominated by Salicornia dolichostachya, a pioneer Glasswort species, and covers about 25 ha. Tassel Weed (Ruppia maritima) occurs in this area, along with some Eelgrass (Zostera angustifolia). Eelgrass (Z. noltii) also occurs in Sutton Creek. Cordgrass (Spartina anglica) occurs in places but its growth is controlled by management. Green algal mats (Enteromorpha spp., Ulva lactuca) cover large areas of the flats during summer. These sediments have a rich macrofauna, with high densities of Lugworms (Arenicola marina) in parts of the north lagoon. Mussels (Mytilus edulis) occur in places, along with bivalves such as Cerastoderma edule, Macoma balthica and Scrobicularia plana. The small gastropod Hydrobia ulvae occurs in high densities in places, while the crustaceans Corophium volutator and Carcinus maenas are common. The sediments on the seaward side of North Bull Island are mostly sands. The site extends below the low spring tide mark to include an area of the sublittoral zone. Three Rare plant species legally protected under the Flora Protection Order 1987 have been recorded on the North Bull Island. These are Lesser Centaury (Centaurium pulchellum), Hemp Nettle (Galeopsis angustifolia) and Meadow Saxifrage (Saxifraga granulata). Two further species listed as threatened in the Red Data Book, Wild Sage (Salvia verbenaca) and Spring Vetch (Vicia lathyroides), have also been recorded. A rare liverwort, Petalophyllum ralfsii, was first recorded from the North Bull Island in 1874 and has recently been confirmed as being still present there. This species is of high conservation value as it is listed on Annex

II of the E.U. Habitats Directive. The North Bull is the only known extant site for the species in Ireland away from the western seaboard. North Dublin Bay is of international importance for waterfowl. During the 1994/95 to 1996/97 period the following species occurred in internationally important numbers (figures are average maxima): Brent Geese 2,333; Knot 4,423; Bar-tailed Godwit 1,586. A further 14 species occurred in nationally important concentrations - Shelduck 1505; Wigeon 1,166; Teal 1,512; Pintail 334; Shoveler 239; Oystercatcher 2,190; Ringed Plover 346; Grey Plover 816; Sanderling 357; Dunlin 6,238; Blacktailed Godwit 156; Curlew 1,193; Turnstone 197 and Redshank 1,175. Some of these species frequent South Dublin Bay and the River Tolka Estuary for feeding and/or roosting purposes (mostly Brent Goose, Oystercatcher, Ringed Plover, Sanderling, Dunlin). The tip of the North Bull Island is a traditional nesting site for Little Tern. A high total of 88 pairs nested in 1987. However, nesting attempts have not been successful since the early 1990s. Ringed Plover, Shelduck, Mallard, Skylark, Meadow Pipit and Stonechat also nest. A well-known population of Irish Hare is resident on the island The invertebrates of the North Bull Island have been studied and the island has been shown to contain at least seven species of regional or national importance in Ireland (Orders Diptera, Hymenoptera, Hemiptera). The main landuses of this site are amenity activities and nature conservation. The North Bull Island is the main recreational beach in Co Dublin and is used throughoutthe year. Much of the land surface of the island is taken up by two golf courses. Two separate Statutory Nature Reserves cover much of the island east of the Bull Wall and the surrounding intertidal flats. The site is used regularly for educational purposes. North Bull Island has been designated a Special Protection Area under the E.U. Birds Directive and it is also a statutory Wildfowl Sanctuary, a Ramsar Convention site, a Biogenetic Reserve, a Biosphere Reserve and a Special Area Amenity Order site. This site is an excellent example of a coastal site with all the main habitats represented. The holds good examples of ten habitats that are listed on Annex I of the E.U. Habitats Directive; one of these is listed with priority status. Several of the wintering bird species have populations of international importance, while some of the invertebrates are of national importance. The site contains a numbers of rare and scarce plants including some which are legally protected. Its proximity to the capital city makes North Dublin Bay an excellent site for educational studies and research. SITE NAME: SOUTH DUBLIN BAY SAC SITE CODE: 000210 This site lies south of the River Liffey and extends from the South Wall to the west pier at Dun Laoghaire. It is an intertidal site with extensive areas of sand and mudflats, a habitat listed on Annex I of the E.U. Habitats Directive. The sediments are predominantly sands but grade to sandy muds near the shore at Merrion gates. The main channel which drains the area is Cockle Lake. There is a bed of Eelgrass (Zostera noltii) below Merrion Gates which is the largest stand on the east coast. Green algae (Enteromorpha spp. and Ulva lactuca) ar distributed throughout the area at a low density. Fucoid algae occur on the rocky shore in the Maretimo to Dún Laoghaire area. Species include Fucus spiralis, F.vesiculosus, F. serratus, Ascophyllum nodosum and Pelvetia canaliculata. Several small, sandy beaches with incipient dune formation occur in the northern and western sectors of the site, notably at Poolbeg, Irishtown and Merrion/Booterstown. The formation at Booterstown is very recent. Driftline vegetation occurs in association with the embryonic and incipient fore dunes. Typically drift lines occur in a band approximately 5 m wide, though at Booterstown this zone is wider in places. The habitat occurs just above the High Water Mark and below the area of embryonic dune. Species pesent are Sea Rocket (Cakile maritima), Frosted Orache (Atriplex laciniata), Spear-leaved Orache (A. prostrata), Prickly Saltwort (Salsola kali) and Fat Hen (Chenopodium album). Also occurring is Sea Sandwort (Honkenya peploides), Sea Beet (Beta vulgaris) and Annual Sea-blithe (Suaeda maritima). A small area of pioneer salt marsh now occurs in the lee of an embryonic sand dune just north of Booterstown Station. This early stage of salt marsh development is here characterised by the presence of pioneer stands of Glasswort (Salicornia spp.) occurring

below an area of drift line vegetation. As this is of very recent origin, it covers a small area but ample areas of substrate and shelter are available for the further development of this habitat. Lugworm (Arenicola marina) and Cockles (Cerastoderma edule) and other annelids and bivalves are frequent throughout the site. The small gastropod Hydrobia ulvae occurs on the muddy sands off Merrion Gates. South Dublin Bay is an important site for waterfowl. Although birds regularly commute between the south bay and the north bay, recent studies have shown that certain populations which occur in the south bay spend most of their time there. The principal species are Oystercatcher (1215), Ringed Plover (120), Sanderling (344) and Dunlin (2628), Redshank (356) (average winter peaks 1996/97 and 1997/98). Up to 100 Turnstones are usual in the south bay during winter. Brent Geese regularly occur in numbers of international importance (average peak 299). Bar-tailed Godwit (565), a species listed on Annex I of the EU Birds Directive, also occur. Large numbers of gulls roost in South Dublin Bay, e.g. 4,500 Black-headed Gulls in February 1990; 500 Common Gulls in February 1991. It is also an important tern roost in the autumn, regularly holding 2000-3000 terns including Roseate Terns, a species listed on Annex I of the E.U. Birds Directive. South Dublin Bay is largely protected as a Special Protection Area. At low tide the inner parts of the south bay are used for amenity purposes. Bai tdigging is a regular activity on the sandy flats. At high tide some areas have windsurfing and jet-skiing. This site is a fine example of a coastal system with extensive sand and mudflats, a habitat listed on Annex I of the E.U. Habitats Directive. South Dublin Bay is also an internationally important bird site. SITE NAME: ROCKABILL TO DALKEY ISLAND SAC SITE CODE: 003000 This site includes a range of dynamic inshore and coastal waters in the western Irish Sea. These include sandy and muddy seabed, reefs, sandbanks and islands. This site extends southwards, in a strip approximately 7 km wide and 40 km in length, from Rockabill, running adjacent to Howth Head, and crosses Dublin Bay to Frazer Bank in south county Dublin. The site encompasses Dalkey, Muglins and Rockabill islands. The area selected for designation represents a key habitat for the Annex II species harbour porpoise, within the Irish Sea. Population survey data show that porpoise occurrence within the site boundary meets suitable reference values for other designated sites in Ireland. The species occurs year-round within the site and comparatively high group sizes have been recorded. Porpoises with young (i.e. calves) are observed at favourable, typical reference values for the species. Casual and effort-related sighting rates from coastal observation stations are significant for the east coast of Ireland and the latter appear to be relatively stable across all seasons. The selected site contains a wide array of habitats believed to be important for harbour porpoise including inshore shallow sand and mud-banks and rocky reefs scoured by strong current flow. The site also supports Harbour seal (Phoca vitulina) and Grey seal (Halichoerus grypus), for which terrestrial haul-out sites occur in immediate proximity to the site. Bottlenose dolphin (Tursiops truncatus) has also occasionally been recorded in the area. A number of other marine mammals have been recorded in this area including minke, fin and killer whales and Risso’s and common dolphins. Reef habitat is uncommon along the eastern seaboard of Ireland due to prevailing geology and hydrographical conditions. Expansive surveys of the Irish coast have indicated that the greatest resource of this habitat within the Irish Sea is found fringing offshore islands which are concentrated along the Dublin coast. A detailed survey of selected suitable islands has shown areas with typical biodiversity for this habitat both intertidally and subtidally. Species recorded in the intertidal included Fucus spiralis, Fucus serratus, Pelvetia canaliculata, Ascophyllum nodosum, Semibalanus balanoides and Necora puber. Subtidally, a wide range of species include Laminaria hyperborea, Flustra folicacea, Alaria esculenta, Halidrys siliquosa, Pomatocereos triqueter, Alcyonium digitatum, Metridium senile, Caryophyllia smithii, Tubularia indivisa, Mytilus edulis, Gibbula umbilcalis, Asterias rubens, and Echinus

esculentus. These Reefs are subject to strong tidal currents with an abundant supply of suspended matter resulting in good representation of filter feeding fauna such as sponges, anemones and echinoderms. This site is of conservation importance for reefs, listed on Annex I, and Harbour Porpoise, listed on Annex II, of the E.U. Habitats Directive. SITE NAME: NORTH BULL ISLAND SPA SITE CODE: 004006 This site covers all of the inner part of north Dublin Bay, with the seaward boundary extending from the Bull Wall lighthouse across to Drumleck Point at Howth Head. The North Bull Island sand spit is a relatively recent depositional feature, formed as a result of improvements to Dublin Port during the 18th and 19th centuries. It is almost 5 km long and 1 km wide and runs parallel to the coast between Clontarf and Sutton. Part of the interior of the island has been converted to golf courses. A well-developed and dynamic dune system stretches along the seaward side of the island. Various types of dunes occur, from fixed dune grassland to pioneer communities on foredunes. Marram Grass (Ammophila arenaria) is dominant on the outer dune ridges. Species of the fixed dunes include Wild Pansy (Viola tricolor), Kidney Vetch (Anthyllis vulneraria), Bird’s-foot Trefoil (Lotus corniculatus), Pyramidal Orchid (Anacamptis pyramidalis) and, in places, the scarce Bee Orchid (Ophrys apifera). A feature of the dune system is a large dune slack with a rich flora, usually referred to as the ‘Alder Marsh’ because of the presence of Alder (Alnus glutinosa) trees. The water table is very near the surface and is only slightly brackish. Sea Rush (Juncus maritimus) is the dominant species, with Meadowsweet(Filipendula ulmaria) and Devil’s-bit Scabious (Succisa pratensis) being frequent. The orchid flora is notably diverse in this area. Saltmarsh extends along the length of the landward side of the island and provides the main roost site for wintering birds in Dublin Bay. On the lower marsh, Glasswort (Salicornia europaea), Common Saltmarsh-grass (Puccinellia maritima), Annual Seablite (Suaeda maritima) and Greater Sea-spurrey (Spergularia media) are the main species. Higher up in the middle marsh Sea Plantain (Plantago maritima), Sea Aster (Aster tripolium), Sea Arrowgrass (Triglochin maritima) and Thrift (Armeria maritima) appear. Above the mark of the normal high tide, species such as Common Scurvygrass (Cochlearia officinalis) and Sea Milkwort (Glaux maritima) are found, while on the extreme upper marsh, Sea Rush and Saltmarsh Rush (Juncus gerardi) are dominant. The island shelters two intertidal lagoons which are divided by a solid causeway. These lagoons provide the main feeding grounds for the wintering waterfowl. The sediments of the lagoons are mainly sands with a small and varying mixture of silt and clay. Tasselweed (Ruppia maritima) and small amounts of Eelgrass (Zostera spp.) are found in the lagoons. Common Cord-grass (Spartina anglica) occurs in places. Green algal mats (Enteromorpha spp., Ulva lactuca) are a feature of the flats during summer. These sediments have a rich macro-invertebrate fauna, with high densities of Lugworm (Arenicola marina) and Ragworm (Hediste diversicolor). Mussels (Mytilus edulis) occur in places, along with bivalves such as Cerastoderma edule, Macoma balthica and Scrobicularia plana. The small gastropod Hydrobia ulvae occurs in high densities in places, while the crustaceans Corophium volutator and Carcinus maenas are common. The sediments on the seaward side of North Bull Island are mostly sands and support species such as Lugworm and the Sand Mason (Lanice conchilega). The site includes a substantial area of the shallow marine bay waters. The site is a Special Protection Area (SPA) under the E.U. Birds Directive, of special conservation interest for the following species: Light-bellied Brent Goose, Shelduck, Teal, Pintail, Shoveler, Oystercatcher, Ringed Plover, Golden Plover, Grey Plover, Knot, Sanderling, Dunlin, Black-tailed Godwit, Bar-tailed Godwit, Curlew, Redshank,Turnstone and Black-headed Gull. The site is also of special conservation interest for holding an assemblage of over 20,000 wintering waterbirds. The E.U. Birds Directive pays particular attention to wetlands and, as these form part of this SPA, the site and its associated waterbirds are of special conservation interest for Wetland & Waterbirds.

The North Bull Island SPA is of international importance for waterfowl on the basis that it regularly supports in excess of 20,000 waterfowl. It also qualifies for international importance as the numbers of three species exceed the international threshold – Light-bellied Brent Goose (1,548), Black-tailed Godwit (367) and Bartailed Godwit (1,529) (all waterfowl figures given are average maxima for the five winters 1995/96 to 1999/00). The site is the top site in the country for both of these species. A further 14 species have populations of national importance – Shelduck (1,259), Teal (953), Pintail (233), Shoveler (141), Oystercatcher (1,784), Ringed Plover (139), Golden Plover (1,741), Grey Plover (517), Knot (2,623), Sanderling (141), Dunlin (3,926), Curlew (937), Redshank (1,431) and Turnstone (157). The populations of Pintail and Knot are of particular note as they comprise more than 10% of the respective national totals. Species such as Grey Heron, Cormorant, Wigeon, Goldeneye, Red-breasted Merganser and Greenshank are regular in winter in numbers of regional or local importance. Gulls are a feature of the site during winter, especially Black-headed Gull (2,196). Common Gull (332) and Herring Gull (331) also occur here. While some of the birds also frequent South Dublin Bay and the River Tolka Estuary for feeding and/or roosting purposes, the majority remain within the site for much of the winter. The wintering bird populations have been monitored more or less continuously since the late 1960s and the site is now surveyed each winter as part of the larger Dublin Bay complex. The North Bull Island SPA is a regular site for passage waders, especially Ruff, Curlew Sandpiper and Spotted Redshank. These are mostly observed in single figures in autumn but occasionally in spring or winter. The site formerly had an important colony of Little Tern but breeding has not occurred in recent years. Several pairs of Ringed Plover breed, along with Shelduck in some years. Breeding passerines include Skylark, Meadow Pipit, Stonechat and Reed Bunting. The island is a regular wintering site for Short-eared Owl, with up to 5 present in some winters. The site has five Red Data Book vascular plant species, four rare bryophyte species, and is nationally important for three insect species. The rare liverwort, Petalophyllum ralfsii, was first recorded from the North Bull Island in 1874 and its presence here has recently been re-confirmed. This species is of high conservation value as it is listed on Annex II of the E.U. Habitats Directive. A well-known population of Irish Hare is resident on the island The main landuses of this site are amenity activities and nature conservation. The North Bull Island is one of the main recreational beaches in Co. Dublin and is used throughout the year. Two separate Statutory Nature Reserves cover much of the island east of the Bull Wall and the surrounding intertidal flats. North Bull Island is also a Wildfowl Sanctuary, a Ramsar Convention site, a Biogenetic Reserve, a Biosphere Reserve and a Special Area Amenity Order site. Much of the SPA is also a candidate Special Area of Conservation. The site is used regularly for educational purposes and there is a manned interpretative centre on the island.The North Bull Island SPA is an excellent example of an estuarine complex and is one of the top sites in Ireland for wintering waterfowl. It is of international importance onaccount of both the total number of waterfowl and the individual populations of Lightbellied Brent Goose, Black-tailed Godwit and Bar-tailed Godwit that use it. Also of significance is the regular presence of several species that are listed on Annex I of the E.U. Birds Directive, notably Golden Plover and Bar-tailed Godwit, but also Ruff and Short-eared Owl. SITE NAME: SOUTH DUBLIN BAY AND RIVER TOLKA ESTUARY SPA SITE CODE: 004024 The South Dublin Bay and River Tolka Estuary SPA comprises a substantial part of Dublin Bay. It includes the intertidal area between the River Liffey and Dun Laoghaire, and the estuary of the River Tolka to the north of the River Liffey, as well as Booterstown Marsh. A portion of the shallow marine waters of the bay is also included. In the south bay, the intertidal flats extend for almost 3 km at their widest. The sediments are predominantly well-aerated sands. Several permanent channels exist, the largest being Cockle Lake. A small sandy beach occurs at Merrion Gates, while some bedrock shore occurs near Dun Laoghaire. The landward boundary is now almost entirely artificially embanked. There is a bed of Dwarf Eelgrass (Zostera noltii) below Merrion Gates which is the

largest stand on the east coast. Green algae (Enteromorpha spp. and Ulva lactuca) are distributed throughout the area at a low density. The macro-invertebrate fauna is well-developed, and is characterised by annelids such as Lugworm (Arenicola marina), Nephthys spp. and Sand Mason (Lanice conchilega), and bivalves, especially Cockle (Cerastoderma edule) and Baltic Tellin (Macoma balthica). The small gastropod Spire Shell (Hydrobia ulvae) occurs on the muddy sands off Merrion Gates, along with the crustacean Corophiu volutator. Sediments in the Tolka Estuary vary from soft thixotrophic muds with high organic content in the inner estuary to exposed, well-aerated sands off the Bull Wall. The site include Booterstown Marsh, an enclosed area of saltmarsh and muds that is cut off from the sea by the Dublin/Wexford railway line, being linked only by a channel to the east, the Nutley stream. Sea water incursions into the marsh occur along this stream at high tide. An area of grassland at Poolbeg, north of Irishtown Nature Park, is also included in the site. The site is a Special Protection Area (SPA) under the E.U. Birds Directive, of special conservation interest for the following species: Light-bellied Brent Goose, Oystercatcher, Ringed Plover, Golden Plover, Grey Plover, Knot, Sanderling, Dunlin, Bar-tailed Godwit, Redshank, Black-headed Gull, Roseate Tern, Common Tern and Arctic Tern. The E.U. Birds Directive pays particular attention to wetlands, and as these form part of the SPA, the site and its associated waterbirds are of special conservation interest for Wetland & Waterbirds. The site is an important site for wintering waterfowl, being an integral part of the internationally important Dublin Bay complex – all counts for wintering waterbirds are mean peaks for the five year period 1995/96-99/2000. Although birds regularly commute between the south bay and the north bay, recent studies have shown that certain populations which occur in the south bay spend most of their time there. An internationally important population of Light-bellied Brent Goose (525) occurs regularly and newly arrived birds in the autumn feed on the Eelgrass bed at Merrion. Light-bellied Brent Goose is also known to feed on the grassland at Poolbeg. The site supports nationally important numbers of a further nine species: Oystercatcher (1,263), Ringed Plover (161), Golden Plover (1,452), Grey Plover (183), Knot (1,151), Sanderling (349), Dunlin (2,753), Bar-tailed Godwit (866) and Redshank (713). Other species occurring in smaller numbers include Great Crested Grebe (21), Curlew (397) and Turnstone (75). South Dublin Bay is a significant site for wintering gulls, especially Black-headed Gull (3,040), but also Common Gull (330) and Herring Gull (348). Mediterranean Gull is also recorded from here, occurring through much of the year, but especially in late winter/spring and again in late summer into winter. Both Common Tern and Arctic Tern breed in Dublin Docks, on a man-made mooring structure known as the E.S.B. dolphin – this is included within the site. Small numbers of Common Tern and Arctic Tern were recorded nesting on this dolphin in the 1980s. A survey of the dolphin in 1999 recorded Common Tern nesting here in nationally important numbers (194 pairs). This increase was largely due to the ongoing management of the site for breeding terns. More recent data highlights this site as one of the most important Common Tern sites in the country with over 400 pairs recorded here in 2007. The south bay is an important tern roost in the autumn (mostly late July to September). Birds also use the Dalkey Islands to the south. The origin of many of the birds is likely to be the Dublin breeding sites (Rockabill and the Dublin Docks) though numbers suggest that the site is also used by birds from other sites, perhaps outside the state. More than 10,000 terns have been recorded, consisting of Common, Arctic and Roseate terns. The wintering birds within this site are now well-monitored. More survey, however, is required on the wintering gulls and the autumn terns. Booterstown Marsh supports an important population of Borrer’s Saltmarsh-grass (Puccinellia fasciculata), a rare, Red Data Book species that is listed on the Flora (Protection) Order, 1999. The South Dublin Bay and River Tolka Estuary SPA is of international importance for Light-bellied Brent Goose and of national importance for nine other waterfowl species. As an autumn tern roost, it is also of international importance. Furthermore, the site supports a nationally important colony of Common Tern. All of the tern species using the site are listed on Annex I of the E.U. Birds Directive, as are Bartailed Godwit and Mediterranean Gull.


Screening Assessment (Stage 1)

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Appendix E Screening Assessment (Stage 1) to identify the potential for significant effects in the absence of mitigation to the Rockabill to Dalkey Island (cSAC)

Screening Criteria Evaluation Assessment

Brief description of the project or plan The proposal incorporates the first phase of Dublin Port Company’s Masterplan 2012 and comprises: the redevelopment of Alexandra Basin West; the redevelopment of the basin at Berths 52/53; and a capital dredging scheme to deepen the Port’s channel with an associated dumping of dredge spoil at sea.

Brief description of the Natura 2000 Site This site includes a range of dynamic inshore and coastal waters in the western Irish Sea. These include sandy and muddy seabed, reefs, sandbanks and islands. This site is of conservation importance for reefs, listed on Annex I, and Harbour Porpoise, listed on Annex II, of the E.U. Habitats Directive. The Porpoise species occurs year-round within the site and comparatively high group sizes have been recorded. Reef habitat is uncommon along the eastern seaboard of Ireland due to prevailing geology and hydrographical conditions. Expansive surveys of the Irish coast have indicated that the greatest resource of this habitat within the Irish Sea is found fringing offshore islands which are concentrated along the Dublin coast.

Describe the individual elements of the project likely to give rise to impacts on the Natura 2000 Site

Alexandra Basin West - Dismantling and removal of infrastructure and infill material - Quay wall refurbishment/construction (designed to accommodate future dredging to a level of -15m CD) - Ro-Ro berth and jetty construction - Dredging of basin and berths to -10m Chart Datum (CD) - Excavation and restoration of Graving Dock No. #1 - Infilling of Gracing Dock #2 Berth 52/53 - Dismantling and removal of existing infrastructure - Infilling of Berth 52/53 with treated dredged material for land reclamation - Raising of existing surface levels by 1.4m - Quay wall construction - Mooring jetty construction - Construction of a new river side berth - Installation of Ro-Ro ramp Navigation Channel - Dredging of Liffey Channel to -10m CD, from East Link Bridge to the Dublin Bay Buoy, disposal of uncontaminated dredged material at Burford Bank (subject to dumping at sea permit from the EPA) - Construction of surge protection / retaining wall at Poolbeg Marina


2

Screening Criteria Evaluation Assessment

Describe any likely direct, indirect or secondary impacts of the project (either alone or in combination with other plans or projects) on the Natura 2000 Site by virtue of: - Size and scale - Land-take - Distance from the Natura 2000 Site or key features of the Site - Resource requirements (water abstraction etc.) - Emissions (disposal to land, water or air) - Excavation requirements - Transportation requirements - Duration of construction, operation, etc.

The key element of the project which relates to this cSAC is the proposed capital dredging scheme to deepen the navigation channel to -10m CD and associated dumping at sea. The eastern extremity of the dredging works and the dredge spoill disposal site lie within the cSAC boundary. Additional indirect noise disturbance associated with construction works at the port facility, notably piling, is identified with particular regard to harbour porpoises within the cSAC site boundary. The proposed works has the potential for short term or temporary habitat modification at a local scale within the cSAC due to the proposed dredging and dredge material disposal. There are no additional resources or emission requirements associated with this element of the project. Disposal of the dredge spoil at sea, at a licensed dump site west of the Burford Bank, requires assessment of the dispersion, fate and deposition of dredge spoil both in the short time and long term. The capital dredging works will be undertaken during the winter season (October to March) over a six year period, Piling adjacent to the River Liffey Channel will not be permitted between March and May, during the smolt outward migration season. Potential disturbance impacts will be temporary, limited to the period of the construction works, and will revert to background levels post construction.

Describe any likely changes to the Site arising as a result of: - Reduction of habitat area - Disturbance to key species - Habitat or species fragmentation - Reduction in species density - Changes in key indicators of conservation value (water quality etc.) - Climate change

The proposed dredging and disposal of dredge spoil within the cSAC site boundary could potentially increase the suspended sediment concentrations in the surrounding marine environment through the re-suspension of dredged material (in plumes) over the duration of the dredge phase. Proposed construction works at Alexandra Basin West and Berth 52/53 require piling which has the potential to give rise to noise emissions to air and water resulting in disturbance to harbour porpoise populations within the cSAC site boundary. Proposed dredging works within and adjacent to the cSAC site boundary, in addition to increased vessel movements within the shipping channel, would have the potential to result in further disturbance to this species. This may give rise to species fragmentation within the cSAC and the reduction in foraging area for harbour porpoise. Dredging and disposal of dredge spoil material west of the Burford Bank has the potential to give rise to water quality impacts, particularly with regard to increased suspended sediments, affecting both the Annex I reef habitat within the cSAC, as well as the Annex II harbour porpoise. The dredging and disposal works will also be subject to permit by the EPA through the application for a Dumping at Sea Permit.

Describe any likely impacts on the Natura 2000 Site as a whole in terms of: - Interference with the key relationships that define the structure of the Site - Interference with the key relationships that

The structure and function of the Annex I Reef habitat designated within the cSAC would not be directly affected by the dredging works; however there may be potential risk for alterations to the sediment regime and tidal regime both during and after dredging works in the outer channel and therefore depending on the community structure of the reef habitat potential for indirect effects may exist arising from siltation and smothering.


3

Screening Criteria Evaluation Assessment define the function of the Site As elements of the works will take place within the cSAC there is therefore potential for direct impacts in

terms of interference with the structure and function of the mobile harbour porpoise population in terms of spatial and temporal habitat availability affected by increased noise impacts, prey species availability and water quality. Indirect impacts reflect the foregoing, extending beyond the proposed works area within the cSAC.

Provide indicators of significance as a result of the identification of effects set out above in terms of: - Loss - Fragmentation - Disruption - Disturbance - Change to key elements of the Site (e.g. water quality etc.)

There would be no permanent direct habitat loss within the cSAC; however, there will be short term, temporary habitat loss affecting harbour porpoise which may potentially be significant. There will be no direct habitat loss affecting Annex I Reef habitat. Indirect habitat loss may occur where harbour porpoise are affected by increased noise disturbance arising from piling works at Alexandra Basin West and Berth 52/53 and from dredging and dredge spoil disposal west of the Burford Bank within the cSAC; this has the potential to give rise to fragmentation of habitat for this species, in the event of noise levels giving rise to aversive behaviour. The deterioration in water quality within the cSAC is evaluated as being potentially significant as direct damage to the physical quality of the environment in terms of water quality may directly and indirectly affect the qualifying interests of the cSAC. Accidental spillages of polluting substances which could affect benthic fauna & water quality or features of interest both habitats and species would be potentially significant should an incident occur.

Describe from the above those elements of the project or plan, or combination of elements, where the impacts are likely to be significant or where the scale or magnitude of impacts is not known

This assessment identifies the potential for direct and indirect impacts affecting the Annex I Reef habitat and the Annex II harbour porpoise, listed as qualifying interests of this site. Potential impacts affecting Reef habitat arise with regard to increased suspended sediments during dredging, resulting in smothering of these habitats and their biological communities within the cSAC. The significance of these effects will be evaluated with reference to the coastal processes modelling undertaken to inform the development, in the context of the overall Natura Impact Statement. The proposed works at Alexandra Basin West and Berth 52/53 require elements of piling and noise-generating activities during construction which would have the potential to transmit through the water resulting in behavioural responses from harbour porpoise within the cSAC. Additionally, dredging and dredge spoil disposal will be undertaken adjacent to and within the cSAC boundary, giving rise to further noise disturbance and potential turbidity effects on this species within a localized area. The significance of these effects will be evaluated fully within the Natura Impact Statement.

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