Environment Agency appropriate assessment: Pembroke Power Station

Environmental Permit

Report – Final v 2.5

- 1 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Executive summary

Purpose An ‘Appropriate Assessment’ (AA) as required by Regulation 61 of the Conservation of Habitats and Species Regulations (in accordance with the Habitats Directive (92/43/EEC), has been carried out on the application for an environmental permit for a 2100 MW natural gas-fired combined cycle gas turbine (CCGT) power station, near Pembroke. This Appropriate Assessment is required before the Environment Agency can grant an Environmental Permit and consider the implications of the environmental permit on the Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers SAC.

Approach The purpose of the AA is to ensure that the granting of an environmental permit does not result in damage to the natural habitats and species present on sites protected for their important wildlife. In this sense, the AA is similar to an environmental impact assessment with special focus on wildlife of international and national importance. In technical terms an, AA is a legal requirement to determine whether activities (not necessary for nature conservation) could adversely affect the integrity of the conservation site(s), either alone or in combination with other activities, and given the prevailing environmental conditions. It is required before the Agency, as a competent authority, can grant permission for the project. An adverse effect on integrity is one that undermines the coherence of a sites ecological structure and function, across its whole area, that enables the site to sustain the habitat, complex of habitats and/or levels of populations of the species for which the site is important. The AA was carried out in view of the conservation objectives for the sites, as determined by the Countryside Council for Wales (CCW), and having due regard to their advice. Particular attention was paid to: ƒ the current conservation status of designated ‘special interest’ habitats and species present on the sites; ƒ the physical, biological and chemical effects of potential hazards from the environmental permit; ƒ the scale and duration of effects; and ƒ the likely ecological response to the anticipated changes. The AA followed national procedures, explained in section 1c, which were devised in conjunction with CCW and Natural England (NE). These procedures have been reviewed annually (since 2003) and endorsed as fit-for-purpose by CCW and NE. The complexity of the Milford Haven ecosystem, the need to make certain reasonable assumptions in the mathematical models used to predict environmental changes and minor scientific uncertainties about the precise biological responses to environmental change, meant that we have used expert judgement to reach our conclusion about effects and impacts. Internal experts have confirmed that the models used have been judged to be fit for purpose and robust, having been developed over many years using measured information. The source data, assumptions and the approach we used in reaching conclusions have been internally and externally peer-reviewed, and endorsed, by international experts, with particular knowledge of Milford Haven.

- 2 - We were advised by CCW that the main reasons for some of the habitats being in unfavourable conservation status are habitat loss and nutrient enrichment. Other factors of potential concern included toxic contamination, artificial changes in temperature, physical damage, siltation, turbidity and smothering. All of these factors have been assessed as part of the AA, but most scrutiny was focused on three major concerns of toxic contamination, nutrient enrichment and temperature effects, due to concerns from CCW. The conclusions below reflect our findings for both Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers SAC, due to the features overlapping between both designated sites.

Toxic contamination The proposed power station intends to use sodium hypochlorite as a biocide in the cooling water to prevent fouling of the cooling water system. The effects of the use of sodium hypochlorite on the benthic and planktonic habitats and species were assessed using mathematical modelling that included reasonable assumptions about the size of the ’mixing zone’ in the Haven. A mixing zone is defined as ‘the ‘area of water within which we are prepared to accept Environmental Quality Standard (EQS) exceedance’, within the Environment Agency document ‘WQTAG160’ and is common practice for discharges to the marine environment. Evidence suggests that the effects of the residual biocide in the Haven would be small and not significant because: ƒ the decay rate is rapid (a few minutes); ƒ the bioaccumulation risk is minimal; ƒ the volume of water affected per tidal cycle would be small (0.26% of tidal volume of the Milford Haven at average equinox springs tide); and ƒ the mixing zone area would coincide with a very small proportion (<2%) of mudflat and sandflat habitat (the feature most predominantly found within the mixing zone). In our opinion the potential effects of the very localised influence of sodium hypochlorite on benthic communities and on planktonic life-stages of benthic fauna would not adversely affect the ecological functioning of the sites. The typical species found within the mixing zone are widely found within the rest of the protected site, outside of the mixing zone. Equally no acute effect is occurring which would adversely affect the site integrity of the protected features.

Changes to the thermal regime The extent and impact of heated water discharged from the direct cooling process were assessed by detailed mathematical models using tidal cycle information to establish the mixing zone and the resulting thermal ‘footprint’ in the Haven. The thermal footprint is considered to be the area where water temperature is likely to be +2ºC above ambient (background). The extent of the thermal footprint will vary with the state of the tide and the tidal cycle. It is estimated that for 95% of the time, the footprint will coincide with 3.9% of the water surface and 1.6% of the sea-bed in the Haven. It is estimated that the volume of discharged water will be 0.26% of tidal volume of the Milford Haven at average equinox spring tide.

- 3 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 In our opinion migratory fish will not be inhibited by the thermal plume and will be able to pass through the Haven. Cefas (Centre for Environment, Fisheries and Aquaculture Science) agreed with this conclusion in their response to our consultation. We also believe that any changes in the benthic flora and fauna resulting from the thermal plume will be localised and that, overall, the communities will remain typical for the habitat which Pembroke Marine SAC is designated.

Physical damage The risk of physical damage to the site has been assessed. Given that a channel has already been dredged (not part of this EPR permit) and that the velocity of the discharge water will reduce greatly in the vicinity of the discharge, due to the natural velocity of the tidal waters, the proposed flow from the discharge will cause no adverse effects.

Siltation & Turbidity & Smothering The risks of siltation, turbidity and smothering have been assessed. We are confident that the levels of siltation and turbidity will remain within the wide range of natural parameters for this estuary. Intertidal organisms in the vicinity of the cooling water discharge are resilient and adaptable, and as a result can easily tolerate exposure to highly turbid and silty waters. Equally, the habitats and species concerned, are resilient and adaptable to smothering from sediment and detritus, as this is typical of the environment that they are adapted to live within.

Nutrient enrichment and Habitat loss Nutrient enrichment Using the proposed emission data provided by the applicant, together with the latest Cefas information (Aldridge & Painting 2011) on nutrients in Pennar Gut, we have modelled the potential effects. As the addition or redistribution of nutrients has the potential to have adverse effects on habitats and species, in particular the eel grass beds found within Pennar Gut, suitable mitigation has been proposed by the applicant. The mitigation will be in the form of the removal of any process contribution of phosphate from the site discharge together with a reduction in phosphate from the discharge of a sewage treatment works close to the Pennar Gut. This will ensure that there is a net reduction in the amount of phosphate in the Pembrokeshire Marine SAC and enhance protection of the eel grass beds. As a result of the mitigation and using detailed modelling together with internal and expert opinion, we have ascertained that nutrient levels will not increase significantly and the re- distribution caused by the abstraction and discharge of cooling water will not cause a significant increase in algal growth. Habitat loss The proposed cooling water will discharge into an already dredged channel (not part of this EPR permit) and velocities will dissipate quickly over the adjacent mudflat shallows, therefore avoiding excessive erosion. Our external marine experts consider that the sediment and benthic fauna will quickly adapt to the new environmental conditions; any effect would be localised and not have an adverse effect on the integrity of the mudflats or of the site. In particular, we believe that the risk of smothering of eel-grass due to an increase in turbidity and siltation is not significant across the site.

- 4 - In combination effects Another technical aspect of the AA is the assessment of ‘in combination’ effects. This is required to determine whether this activity could have additive or synergistic effects with other activities. The potential effects of these factors acting ‘in combination’ with each other and with other activities affecting the SACs were also taken into account, using the same national procedures, explained in section 1c, which were devised in conjunction with CCW and Natural England. The in-combination assessment found that some of the elements of favourable conservation status, that have been included in the Conservation Objectives for the features, will not be met, but as the scale of the effect is such that it can be considered trivial and thus not long term, there will not be an adverse effect on the integrity of the site (listed in Appendix 1).

Overall conclusion After taking all relevant factors into consideration and subjecting our assumptions to internal and external peer review, as well as consultation with Cefas and CCW, we the competent authority for this environmental permit, have concluded that:-

ƒ changes to the physical nature of the habitat due to the existing abstraction and proposed discharge would be within the natural dynamics of the tidal system. There would not be a measurable reduction on the extent or structure of the habitat; ƒ the addition or redistribution of nutrients has the potential to have adverse effects. However the nutrient mitigation discussed in section 5.3 counteracts this with a net decrease in the amount of phosphate entering the system. This will result in less growth of nuisance algae, leading to improvement in the eel grass beds (a typical feature of the Pembrokeshire Marine SAC); ƒ the volume and dynamics of the tidal currents will very quickly mix, dilute and dissipate any residual toxic effect from the discharge. Localised changes in species living with the sediments would not affect the overall extent of their distribution and ability to grow, reproduce and migrate; ƒ the effect of the thermal plume (and its cumulative effect on prevailing conditions such as nutrient levels and toxic chemicals) would not significantly affect the ecology of the water column; ƒ the ambient diurnal temperature range for inter-tidal habitats far exceeds the effects of the predicted thermal plume, so other than very localised effects near the point of discharge, there would be no significant impact on the biological communities living in the sediment because they are well adapted to living in such variable conditions; ƒ loss of fish through entrainment would not affect their overall populations and the loss of plankton would not be significant given the size of the site and the natural fecundity of the typical species (the potential reproductive capacity of an individual or population).

On this basis, we consider that the character and dynamics of the designated sites and the natural resilience of the habitats and species in the ecosystem (e.g. the capacity of species to adapt to localised impacts, replenish their populations) would be able to compensate for the predicted localised physical, chemical and temperature changes, which consequently will not adversely affect the structure and ecological functioning of the site. The detailed evidence and reasoning for making these conclusions is included in the technical sections (chapters 5-6) of the appropriate assessment.

- 5 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The Environment Agency, as an environmental regulator has acted reasonably so as to reduce any scientific doubt in its conclusions. We have listened to the advice of the consultees and delivered a precautionary assessment, using the best available information. We are convinced that this appropriate assessment meets the site integrity test and that the proposed Environmental Permit, with conditions and restrictions imposed, will not have an adverse effect on Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers SAC.

- 6 - Contents

Executive summary...... 2 Purpose ...... 2 Approach ...... 2 Toxic contamination...... 3 Changes to the thermal regime...... 3 Physical damage ...... 4 Nutrient enrichment and Habitat loss...... 4 In combination effects...... 5 Overall conclusion...... 5 Contents...... 7 Part A: Technical consideration ...... 11 Figure 1. Map showing PPP location and European site(s): ...... 11 Site details ...... 12 Project team...... 12 Amendment history...... 13 Table 1: Summary table of the European protected features identified at Stage 2, within the document 'Appendix 11 EPR final revised Apr 11’...... 14 Introduction ...... 16 1a Summary of the proposal ...... 16 Figure 2. Map showing the location of the cooling water intake and discharge within Milford Haven waterway...... 17 1b Relevant background to ‘The European Habitats Directive’ and ‘Appropriate Assessments’ ...... 17 European Commission guidance on implementing the Habitats Directive in Estuaries and Coastal Zones...... 20 1c How we reached our conclusions...... 21 Figure 3 Summary diagram showing how the appropriate assessment was carried out and the sources of information and advice...... 23 1d Information and how it was used...... 23 1e Key factors determining our conclusion about adverse impact on site integrity ...... 29 1f Introduction summary...... 32 2. Application history...... 33 3. How we have considered the views of the Countryside Council for Wales .... 34 4. Individual feature summary...... 37 Coastal habitats sensitive to abstraction...... 37 Figure 4.1: Location of the coastal lagoon priority feature...... 37 Estuarine and intertidal habitats...... 38 Figure 4.2: Location of estuaries feature...... 39 Figure 4.3: Location of Atlantic salt meadows feature ...... 40 Large shallow inlets and bays ...... 40 Figure 4.4: Location of large shallow inlets and bays...... 41 Mudflats and sandflats not covered by seawater at low tide...... 42 Figure 4.5: Indicative location of mudflats and sandflats feature ...... 42 Submerged marine habitats...... 43 Reefs...... 43 Figure 4.6: Indicative location of reef feature ...... 44

- 7 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 4.7: Indicative location of sandbank habitat feature...... 45 Submerged or partially submerged sea caves ...... 45 Figure 4.8: Indicative location of sea caves feature ...... 46 Coastal Plants...... 46 Figure 4.9: Location of shore dock...... 47 Marine mammals ...... 48 Grey seal ...... 48 Figure 4.10: Indicative location of grey seals and distribution of grey seal pupping sites...... 49 Anadromous fish...... 49 Mammals of riverine habitats ...... 51 Figure 4.11: Indicative location map of otters ...... 52 Overall conservation status...... 52 5. Technical assessment ...... 53 5.1 Toxic contamination - Sodium hypochlorite biocide (Chlorination agent) 53 Figure 5.1 Laboratory TRO decay curves using Pembroke seawater June 2010 (figure 2.6.1, report ENV/445/2011). The proposed emission value is 0.05mg/l. 57 Figure 5.2 Sea surface (left map) and sea bed (right map) distribution of percentage of time that the 10µg l-1 95 percentile TRO, is exceeded, at a base case decay rate (0.03/min) (figures A.3.1 & A.3.2 RWE report ENV/451/2011) 60 Figure 5.3 Sea surface (left map) and sea bed (right map) distribution of percentage of time that the 10µg l-1 95 percentile TRO, is exceeded, at the precautionary decay rate (0.02/min) (figure A.3.3 & A.3.4 RWE report ENV/451/2011) ...... 60 Figure 5.4 The location of Neyland Weir Pool in relation to the approximate TRO exceedance at the seabed and surface...... 64 Figure 5.5: Biotopes in the area of the proposed power station ...... 69 Figure 5.6. The location of the indicative reef feature in relation to the 10µg l-1 95 percentile TRO exceedance 0.02/min decay rate...... 71 5.1.6 Summary of the potential effects of toxic contamination...... 74 5.1.6.1 Individual feature conclusions ...... 76 5.1.8 Site integrity implications with respect to toxic contamination...... 78 Table 5.8: Conclusions on site integrity, assessing the impact of biocide toxic contamination in relation to the conservation objectives of special interest features and the site...... 80 5.2 Changes in thermal regime ...... 81 5.2.1 Description of thermal loading ...... 81 Figure 5.7: Location of the Power Station and the position of the cooling water intake and outfall...... 82 Figure 5.8: Percentile exceedance distribution of +2°C at sea bed (figure 106, EPR application)...... 87 Figure 5.9 Sea bed area exceeding temperature rise thresholds (fig 2.1.3 of ENV/463/2011) ...... 88 Figure 5.10: Percentile exceedance distribution of +2°C at sea surface (figure 107, EPR application)...... 89 Figure 5.11: Milford Haven cross section at and near outfall channel showing exceedance of +2oC at low water spring at spring equinox (figure 109, RWE CES 2010)...... 90

- 8 - Figure 5.12 Extent of the cumulative thermal impacts on the estuary feature (sea surface and sea bed), indicating the 0.2°C change which triggered further investigation in this appropriate assessment, and the extent of the 2°C exceedance plume...... 97 Figure 5.13 Sensitivity of biotopes to thermal impacts (RWE CES 2010, figure 117) 100 Figure 5.14: Location of reef feature in relation to the thermal exceedance on the sea bed...... 103 5.2.7 Summary of the potential effects of change in thermal regime...... 105 5.2.8 Site integrity implications with respect to change in thermal regime 110 Table 5.18: Initial conclusions on site integrity, assessing the impact of the thermal regime in relation to the conservation objectives of special interest features and the site...... 111 5.3 Nutrient enrichment...... 112 Figure 5.15 Graph showing available nitrogen and phosphorus versus salinity for all sampling points in the Milford Haven waterway from 2000 to 2011. 114 Figure 5.16 Map showing location of opportunistic macroalgae, eelgrass and saltmarsh (indicative Atlantic salt meadow) ...... 119 5.3.4.4 Summary of conclusions for nutrient enrichment ...... 121 5.3.5 Site integrity implications with respect to nutrient enrichment...... 122 Table 5.19: Conclusions on site integrity, assessing the effect of nutrient enrichment in relation to the conservation objectives of special interest features 123 5.4 Habitat loss and Physical damage ...... 124 5.4.3 Summary of the potential effects of habitat loss and physical damage 126 Table 5.20: Conclusions on site integrity, assessing the effect of habitat loss and physical damage in relation to the conservation objectives of special interest features...... 128 5.5 Siltation and turbidity...... 129 5.5.3 Summary of the potential effects from turbidity and siltation...... 131 Table 5.21: Conclusions on site integrity, assessing the effect of siltation and turbidity in relation to the conservation objectives of special interest features. 134 5.6 Smothering...... 135 Table 5.22: Conclusions on site integrity, assessing the effect of smothering in relation to the conservation objectives of special interest features...... 138 5.23 Alone conclusion summary table...... 139 5.7 Cross comparison of potential effects on features alone...... 140 6. In combination assessment ...... 143 6.1. Overview ...... 143 6.2. PPP considered ‘in combination’...... 143 Table 6.1 – PPP considered and PPP included in the in combination assessment...... 145 6.3. Receiving water characteristics...... 154 Figures 6.1 to 6.7 – Tidal ellipses (spring tides) in Milford Haven...... 155 Figure 6.8 – Admiralty tidal measuring stations in Milford Haven ...... 156 6.4. Overview by type of effect...... 157 6.5. Toxic contamination ...... 161

- 9 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Table 6.3a Process contributions to W1 discharge...... 162 The process contributions in Table 6.3a above give rise to point of discharge concentrations as set out in Table 6.3b on the following page. Concentrations are displayed both in absolute terms and relative to ambient and each EQS...... 162 Table 6.3c: Contaminant loads arising from W1 discharge...... 165 6.5.2. Mechanisms for in combination effects...... 167 6.5.4. In combination effects on interest features ...... 171 6.5.5. Summary of in combination effects of toxic contamination ...... 177 6.6. Changes in thermal regime ...... 178 6.6.1. Sources of the hazard ...... 178 6.6.5. Summary of in combination effects of thermal loads ...... 187 6.7. Nutrient enrichment...... 188 6.7.4. In combination effects on interest features ...... 189 6.7.5. Summary of in combination effects of nutrient enrichment ...... 191 6.8. Habitat loss and physical damage...... 192 6.8.5. Summary of in combination effects of habitat loss or damage to interest features ...... 195 6.9. Siltation and turbidity ...... 196 6.9.5. Summary of in combination effects of siltation and turbidity ...... 200 6.10. Smothering ...... 201 6.11. Entrainment and impingement ...... 202 Table 6.11 Predicted residual losses due to impingement at Pembroke Power Station with AFD and fish return systems in place and an intake velocity of -1 0.215 m s . AFD and FRR efficiency data are taken from Turnpenny and O’Keeffe (2005) ...... 205 6.12 In combination conclusion ...... 207 Table 6.12 – The sum of the influences acting on a feature from all PPP.... 209 6.12.1 Cross comparison of potential effects on features ...... 212 Sum or all influences...... 215 References...... 216 Appendices (supplied separately to this document)...... 222 Annex...... 222 Environment Agency conclusion ...... 223 Part B: Final appropriate assessment record...... 224

- 10 - Part A: Technical consideration

Type of permission, plan Environmental Permit under the Environmental Permitting (England or project (PPP) and Wales) Regulations 2010 Environment Agency EA/EPR/DP3333TA/A001 reference number National grid reference SM92700 02600 Permit description Pembroke Power Station The environmental permit includes: Emissions to air, direct cooling water discharge, boiler blow through or steam purge, commissioning and operational phases of the water treatment plant, boiler blowdown and acid clean. NB – The acid clean is no longer part of this permit application with all waste products tankered off the site.

Figure 1. Map showing PPP location and European site(s):

- 11 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Site details

Name and legal Two European sites, progressed through to this appropriate assessment (Stage 3) status of the from the likely significant effect test (Stage2) - 'Appendix 11 EPR final revised Apr European sites 11’, as shown in Table 1. These sites are:- Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC)

Afonydd Cleddau / Cleddau Rivers Special Area of Conservation (SAC)

Project team

Project Sponsor: Steve Brown Project Executive: John Hogg Project Manager: Mel Bischer Water Quality Dave Lowthion, Alastair Pratt, Mike Best, Paul Edwards, Lucie Haines, Roger Proudfoot Fisheries Peter Gough, Steve Colclough, Ida Tavner Water Quality - Modelling Andrzej Nowosielski, Norman Babbedge, Richard Armitage, Pete Jonas Toxicology Kate Cameron, Environmental Toxicity Advisory Service (ETAS) Habitats Directive Advisors Craig Rockliff, Nicola Riley, Richard Handley, Kate Collins, Paul Raven. Legal Stephen Prentice, Huw Williams, Ralph Seymour Geographical Information John Farnhill Systems (GIS) Energy efficiency John Henderson, Ralph Seymour Noise Tony Clayton, Simon Scott Air Quality Matthew Bevington, Colin Powlesland Permit conditions Richard Chase, Vic Whiteley, Ross Hockley External Marine experts Dr Keith Hiscock and Dr Nick Pope

- 12 - Amendment history

Version Description Author Reviewed Date number 1.0 Initial Draft Kate Collins 01.03.11 1.0a Initial Draft Kate Collins 15.03.11 1.0b Initial Draft Kate Collins 17.03.11 1.0c Initial Draft Kate Collins 21.03.11 1.0d Initial Draft Kate Collins 22.03.11 1.0e Initial Draft Kate Collins 25.03.11 1.0f Initial Draft Kate Collins 28.03.11 1.1 Draft document for CCW Kate Collins & Craig Rockliff 30.03.11 1.2 Draft document for CCW Kate Collins & Craig Rockliff 03.05.11 1.3 Draft document Kate Collins, Craig Rockliff, Paul 18.05.11 Raven, Mel Bischer 1.4 Draft document Craig Rockliff & Richard Handley 03.06.11 2.0 Draft document for Minded To Craig Rockliff & Richard Handley 20.06.11 2.1 Draft document – minor Mel Bischer 11.07.11 2.2 Draft document post Minded Craig Rockliff & Richard Handley 15.08.11 2.3 Draft document post Craig Rockliff & Richard Handley 06.09.11 2.4 Draft Document Craig Rockliff & Richard Handley 30.09.11 2.4 Draft document sent to Welsh Craig Rockliff & Nicola Riley 25.10.11 Government 2.5 Final Draft Document Craig Rockliff 03.11.11 2.5 Final Document Mel Bischer 08.11.11

- 13 - Table 1: Summary table of the European protected features identified at Stage 2, within the document 'Appendix 11 EPR final revised Apr 11’

EU Sites Species/habitats enrichment enrichment loss Habitat Physical damage Siltation Turbidity Smothering Acidification Change in salinity regime Disturbance (noise) Entrapment (Entrainment / Impingement) Priority feature Priority feature Toxic contamination in Changes regime thermal Nutrient Castlemartin Coast SPA Chough (Pyrrhocorax pyrrhocorax) N - AQ N N - AQ N - AQ N N N N N N N N

Limestone Coast of South West Wales / Arfordir Fixed dunes with herbaceous vegetation (`grey * Calchfaen de Orllewin Cymru SAC dunes`) N N N N N Vegetated sea cliffs of the Atlantic and Baltic coasts N N N N N N N N Caves not open to the public & Submerged or partially submerged sea caves N N N N N N N Semi-natural dry grasslands and scrubland facies: on calcareous substrates (Festuco-Brometalia) N - AQ N - AQ N N N European dry heaths N N - AQ N N N N Early gentian (Gentianella anglica) N - AQ N - AQ N N N N Petalwort (Petalophyllum ralfsii) N - AQ N - AQ N N N N Greater horseshoe bat (Rhinolophus ferrumequinum) N - AQ N - AQ N N N N N

Pembrokeshire Bat Sites and Bosherston Lakes/ Hard oligo-mesotrophic waters with benthic vegetation Safleoedd Ystlum Sir Benfro a Llynnoedd of Chara spp. Bosherston SAC N - AQ N N - AQ N N N N N Greater horseshoe bat (Rhinolophus ferrumequinum) and Lesser horseshoe bat (Rhinolophus hipposideros) N - AQ N - AQ N N N N N Otter (Lutra lutra) N N N N N N N N N N N

Pembrokeshire Marine SAC Coastal lagoons * Y N Y N N N N N N N N N Estuaries Y Y Y Y Y Y Y Y N N N N Atlantic salt meadows (Glauco-Puccinellietalia

maritimae) N N N N N N N Y N N N N Large shallow inlets and bays Y Y Y Y Y Y Y Y N N N N Mudflats and sandflats not covered by seawater at low tide Y Y Y Y Y Y Y Y N N N N Reefs Y Y Y Y Y Y Y Y N N N N Sandbanks which are slightly covered by sea water all the time Y N N N N N N N N N N N Submerged or partially submerged sea caves Y N N N N N N N N N N N Shore dock (Rumex rupestris) N - AQ N - AQ N N N N Grey seal (Halichoerus grypus) Y Y Y N N N N N N N Allis shad (Alosa alosa), River lamprey (Lampetra fluviatilis), Sea lamprey (Petromyzon marinus), Twaite shad (Alosa fallax). Y Y Y N N Y Y N N N N Otter (Lutra lutra) Y Y Y N N N N N N N N

Yerbeston Tops SAC Molinia meadows on calcareous, peaty or clayey-silt- laden soils (Molinion caeruleae) N N N - AQ N - AQ N N N N N Marsh fritillary butterfly (Euphydryas (Eurodryas, N N - AQ N - AQ N N N N N - AQ

- 14 - Hypodryas) aurinia)

Afonydd Cleddau/ Cleddau Rivers SAC Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion * albae) N N N N N N N N N N

Active raised bogs * N - AQ N N - AQ N - AQ N N N - AQ Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation N N N N N N N N N River lamprey (Lampetra fluviatilis) and Sea lamprey (Petromyzon marinus) Y Y Y N N Y Y N N N N Brook lamprey (Lampetra planeri) and Bullhead (Cottus gobio) N N N N N N N N N N N Otter (Lutra lutra) Y Y Y N N N N N N N N

Table 1 Key:- N = No likely significant effect. Grey cell = No hazard present as agreed with CCW. N - AQ = No likely significant effect due to the results of the 'Appendix 11 EPR final revised Apr 11’Air Quality assessment. Orange cell = Indicates the need to assess further in this Appropriate Assessment. N = No likely significant effect, but added on request of CCW. Y = Likely significant effect. Y = Likely significant effect, added on request of CCW. * = Priority habitat.

- 15 - Introduction

1a Summary of the proposal RWE npower have applied for an Environmental Permit for a natural gas-fired combined cycle gas turbine (CCGT) power station with a nominal capacity of approximately 2100 megawatt, near Pembroke. It is proposed that the new power station will be direct sea water cooled, with cooling water being abstracted from Pennar Gut and returned to the Milford Haven waterway to the north of the site (referred to in figure 2), which is within Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC). The proposed screening is consistent with the Environment Agency Best Practice Guidelines for Screening (Turnpenny & O’Keefe, 2005) and the guidance set out in Operational Instruction 1046_08. The issues being considered in this report under the Habitats Regulations include the effects of the thermal discharge and the biocide (i.e. sodium hypochlorite solution) within the cooling water discharge. The emission of nitrogen oxides (a pollutant arising from the natural gas combustion), the process of boiler blowdown, acid clean (which is no longer part of this permit application with all waste products tankered off the site.), steam purge and the non-nutrient chemical aspect of the water treatment plant were all considered not likely to have significant effects at earlier stages of the Habitats Regulations assessment (Appendix 11 EPR final revised April 2011 (EA/EPR/DP3333TA/A001, revised 7 April 2011)). However, these emissions have been re-considered within the in combination section of this appropriate assessment. The intake arrangements include the use of an acoustic fish deterrent and strobe behavioural based deterrents, drum screens of appropriate mesh size and a suitable fish return system. The drum screens within the proposed environmental permit, were considered as part of the Abstraction Licence appropriate assessment. As a result the licence conditions for 22/61/6/156 stipulate that before any abstraction takes place RWE must install, to the satisfaction of the Environment Agency, four drum screens with a mesh size of 6mm or less at the intake structure. The drum screens were also incorporated in the back wash and fish return system along with an acoustic and strobe light deterrent, which are considered to be best practice (Turnpenny & O’Keefe, 2005). They also included the requirement for a monitoring programme to be agreed with the Environment Agency. These conditions were met and this was confirmed by correspondence dated 11 April 20111. Further information on drum screens can be found within section 5.1 of document ‘Appropriate Assessment for Pembroke Power Station (version 3) - Abstraction Licence Application: 22/61/6/0156’, 12th December 2008. This appropriate assessment considers the impacts of the abstraction licence, together with this proposed environmental permit, within section 6.11. The hazards associated with the aerial and aqueous emissions from the proposed power station, and the sensitive habitats and species are identified in the feature list Table 1 of this assessment.

1 Environment Agency letter reference 22/61/6/156 - 16 - Figure 2. Map showing the location of the cooling water intake and discharge within Milford Haven waterway.

1b Relevant background to ‘The European Habitats Directive’ and ‘Appropriate Assessments’

The purpose of the Habitats Directive (92/43/EEC) is to ensure that Member States take concerted action to ensure the long-term conservation of features of special species and habitats. Terrestrial, freshwater, coastal and marine habitats and species that require special conservation to achieve this overall aim are listed in Annexes I and II of the Directive respectively. A series of wildlife sites has been established across the European Union. These comprise Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) - designated under the European Birds Directive; (79/409/EEC), collectively known as the Natura 2000 network. These sites provide a core network of terrestrial, freshwater, coastal and marine sites that are essential for conserving the habitats and species of European importance (i.e. those listed in the Annexes) across their natural range (inside and outside protected areas). The technical term for this condition is ‘favourable conservation status’ and achieving it is a key objective of the Habitats Directive. Each Member State has been required to identify, designate and manage wildlife sites (SACs and SPAs) for the Natura 2000 network. These sites were selected, approved and designated primarily on the basis of their habitats and species present and the natural processes that enable the ecological functioning of the site to be maintained or restored. Other conservation measures include (i) legal protection of habitats and species outside these wildlife sites and (ii) the provision of incentives for the management of land, water and the seas to encourage these species and habitats to thrive outside the ‘core’ network of protected sites. The contribution of each Natura 2000 site to achieving favourable conservation status is, in part, related to (but not entirely dependent on) the habitats and species it supports and the natural processes operating in the site. Therefore, sites containing a large proportion of the total habitat or population of species occurring in a Member State or Europe would be expected to be particularly vulnerable to human impacts.

- 17 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 However, not all sites are entirely natural; indeed, most SACs and SPAs in the UK and other more industrialised regions of Europe are directly or indirectly affected to some extent by human activity. This is particularly true in estuaries, shallow bays and inlets, with Milford Haven providing a good example.

Conservation objectives

The conservation objectives inform the management of the site and the regulation of activities within the site. They also inform the setting of environmental quality standards to control pollution and activities outside the site which may affect it. For terrestrial SACs, these conservation objectives are drawn up by the statutory nature conservation body; for marine SACs a consortium of ‘relevant authorities’(e.g. planning authorities, environmental regulators, nature conservation body, port authority) is responsible for agreeing to a management plan (a ‘Regulation 33 scheme of management’) informed by conservation objectives provided by the nature conservation body. The conservation objectives support the overall aim of maintaining the site in a condition which contributes to the overall coherence of the Natura 2000 network. This is through maintaining or restoring at favourable conservation status those habitats and species (for which the site was designated) across their natural range. The conservation objectives should be based on an assessment of the local conservation status of the habitats and species for which the site was designated, the relative importance of the site for the coherence of Natura 2000 and reflect the threats of degradation to which the site is exposed (European Commission Staff Working Document on Integrating Biodiversity and Nature Protection into Port Development, 8 March 2011). The nature conservation body (Countryside Council for Wales in this instance) is responsible for assessing, monitoring and reporting on the local conservation status of habitats and species in the sites-as required by Article 17 of the Directive. The Joint Nature Conservation Committee (www.jncc.gov.uk) co-ordinates reporting of this information (including an overall assessment of conservation status of individual habitats and species) on a UK basis to the European Commission every 6 years.

The legal tests for protecting Natura 2000 from damaging activities

The Habitats Directive imposes strict legal tests to ensure that the condition of a conservation site and, among other things, its ability to contribute to the ‘favourable conservation status’ of habitats and species across their natural range is maintained. Otherwise, the ability of a site to fulfil its purpose individually and within the Natura 2000 network would be compromised by activities that would damage or reduce the extent and distribution of species or habitats to unacceptable levels, or disrupt the natural processes required to maintain the necessary ecological functioning. This in turn would undermine the ability to achieve, maintain or restore favourable conservation status. The inference to be drawn from the Directive is that each site should be designated on the basis that it is sufficiently resilient to accommodate short and longer-term natural variation and change without compromising the conservation objectives. The legal obligations of the Directive have been transposed into UK legislation, originally as Conservation (Natural Habitats &c) Regulations 1994 (known as the Habitats Regulations 1994, now superseded by the Conservation of Habitats and Species Regulations 2010 (known as the Habitats Regulations 2010).

- 18 - The key legal test, for protecting species and habitats from potential damaging activities is based on Article 6(3) of the Directive. It is specifically designed to ensure that:- (i) the anticipated (likely) adverse effects of any activity (expressed as a ‘plan or project’) are identified and assessed, and (ii) that a decision to authorise that activity should proceed only if the authorising authority has ascertained that there would be no adverse effect on the integrity of the site, i.e. that the plan or project will not compromise the ability of the site to sustain the habitats and species for which the site was originally designated in a way consistent with the conservation objectives. Article 6(4) of the Directive requires that where there are reasons of ‘overriding public interest’ for a development that does damage the site and there are no alternative solutions for its location or design, habitat compensation measures must be taken to offset that damage before the activity is operational.

The role of ‘Appropriate Assessment’ in preventing damaging activities

Regulation 61 of the Habitats Regulations 2010 requires all competent authorities, such as the Environment Agency, to appraise new activities (plans, projects and permissions) for which they have responsibility, in line with Article 6(3) of the Directive and where these are likely to have a significant effect, to carry out an ‘appropriate assessment’. This is, in essence, an environmental impact assessment of the effects on the site. An ‘Appropriate Assessment’ is important because it represents the evidence-collecting and decision-making procedure that allows the competent authority to determine whether an activity, either on its own or in combination with other plans and projects, would adversely affect the integrity of the site. ‘Integrity of the site’ is not defined in legislation but has been defined by the UK Government as ‘the coherence of the site’s ecological structure and function, across its whole area, that enables it to sustain the habitat, complex of habitats and/or the levels of populations of the species for which it was classified [i.e. designated]’. This definition has been cited in the European Commission Guidance on Article 6 of the Directive (Managing Natura 2000 Sites, April 2000). The Directive requires that an activity should be authorised only when it is concluded that site integrity would not be adversely affected by that activity alone or in combination with other plans or projects, in view of its conservation objectives. The conservation objectives are therefore a crucial part of the process because they provide the parameters for assessing individual and cumulative impacts on the habitats and species for which the site was designated. The purpose of the appropriate assessment procedure is to identify the likely risk to the ecological features for which the site was designated, caused by impacts resulting from the proposed activities and other activities already influencing the prevailing environmental conditions of the site. Prevailing environmental conditions are those reasonably foreseeable impacts arising from regulated and unregulated anthropogenic sources and natural sources. They can include, background/diffuse contributions to the site and residual effects of activities that have been completed/implemented. The level of risk is determined by:- (i) the type of expected effects caused by the proposed activity (hazards) i.e. direct or indirect change in physical, chemical or biological parameters; (ii) the sensitivity of habitats and species to those effects; (iii) the likely extent, duration and intensity of exposure of those habitats and species to those hazards.

- 19 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Since the onus is proving no adverse effect (rather than proving that there might be one), any doubts about the significance of impact on site integrity need to be removed as far as reasonably and practicable to do so. This in part relies on the best available information. In coming to a conclusion (as to whether or not there would be no adverse effect), account has to be taken of prevailing environmental conditions, since these may have altered or could be predicted to alter as part of natural change not connected with the proposed or existing activities acting on the site. Removing doubts, in practice, means being convinced about the available scientific information - and commissioning new research or studies if current knowledge is inadequate. This includes the quality of the data and the validity of assumptions and in particular predicted changes derived by surrogate means such as mathematical and ecological models (simulations). Where scientific knowledge is considered inadequate, expert judgement and local knowledge in particular are legitimate contributions to decision-making. Central to this quality assurance and control are: (i) scientific peer review and (ii) applying local knowledge to test assertions and verify conclusions. Our Appropriate Assessment procedure, described in section 1c and Figure 3, was designed to fulfil these requirements.

European Commission guidance on implementing the Habitats Directive in Estuaries and Coastal Zones. The European Commission in January 2011, has recognised the potential conflicts and legal complications associated with damaging activities (such as dredging) caused by industrial and port development in estuaries containing Habitats Directive sites. It has produced practical (non-binding) guidelines to help industry and the various planning, environmental regulation and nature conservation authorities involved reconcile potential problems. The guidelines are progressive in that they ‘go beyond the interpretation of the provisions under Articles 6(3) and 6(4) of the Habitats Directive, in the sense that they focus more on integrated development approaches with strong emphasis on reconciling port development and nature conservation interests (European Commission March 2011). The Commission also recognised that ‘an adaptive management approach for the implementation of a development (plan or project) or a (habitat) compensation scheme may be necessary in the event, due to uncertainty associated with different factors, it is impossible to define all the effects of the plan or project or of a compensation scheme in sufficient detail. In such a situation, a rigorous monitoring scheme and a pre-defined validated package of appropriated corrective measures must be foreseen. Such measures must allow adjusting mitigation and /or compensatory measures to the impacts and make sure that any initial unforeseen effects are being neutralised’ (European Commission March 2011). These recent guidelines are germane to the complexity of factors and scientific uncertainties associated with predicted impacts of Pembroke power station on Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers Special Area of Conservation (SAC).

- 20 - 1c How we reached our conclusions

Key players and responsibilities

We worked closely with the Countryside Council for Wales (CCW), the statutory advisers on nature conservation for the Welsh Government. CCW is responsible for site designation, conservation objectives, assessing monitoring and reporting on the conservation status of special interest and other wildlife features and providing advice during the appropriate assessment process. ‘How we have considered the views of CCW’ is dealt with in section 3 of this appropriate assessment. We ensured that the applicant for the environmental permit (authorising operation of the power station) RWE Npower, provided the relevant physical, chemical and environmental impact information for us to make a reasoned judgement on the effects of the proposed activity. Their data and mathematical/ecological models were checked by our internal experts and consulted on externally with Cefas, with any discrepancies or inadequacies highlighted for further revision. Where further information was required we asked the applicant to provide it. We used our own Environment Agency experts on water and air quality, marine ecology, fisheries and Habitats Directive Appropriate Assessments, and legal team to provide internal peer review and quality control throughout the appropriate assessment. A panel of these experts was convened to inform and agree decisions at important stages (for example at the ‘alone’ and ‘in combination’ stages of the assessment) in the process. We commissioned external internationally-renowned experts2 with an in-depth knowledge of the Pembrokeshire Marine SAC for external peer review. Their role was to ensure that the data used, assumptions and predictions and judgements made about impacts were valid, and if not how they needed to be improved. This applied to our information and judgements and to the queries raised by CCW during the process.

Our Appropriate Assessment procedures

The Habitats Directive does not set out a prescriptive procedure for an Appropriate Assessment, but the European Commission has issued general guidance, including checklists of what to consider in carrying out an assessment (European Commission, November 2001). In the absence of detailed technical guidance, and to support a 10-year programme (2000- 2010) to review all existing Environment Agency permissions that could be affecting Natura 2000 sites (as required by the Habitats Regulations 1994) (Environment Agency 2011), we have developed, tested and used our own technical procedures which are compliant with the Directive and Regulations. Our Appropriate Assessment procedure for new permissions (Environment Agency Operational Instruction 183_1, Habitats Directive: taking a new permission, plan or project through the Regulations) underpins this appropriate assessment. This operational instruction contains a series of generic technical criteria and tests (outlined below) developed by a range of experts and scientists (e.g. specialising in water pollution, air pollution, marine science) and ecologists in a series of task groups and agreed by the Environment Agency, Natural England and CCW and approved by officials at the Department for Environment, Food and Rural Affairs (Defra) and the Welsh Assembly Government in 2003.

2 Dr Keith Hiscock and Dr Nick Pope - 21 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The guidance has been refined and improved since 2003 in light of new scientific information, extensive experience of carrying out appropriate assessments and has been adapted for dealing with new permissions. It is important to point out that although the generic approach and supporting guidance for environmental standards were jointly agreed with the nature conservation bodies they occasionally disagreed with the technical conclusions resulting from our application of the procedures.

The Appropriate Assessment for Pembroke Power Station

The key steps in the Appropriate Assessment for Pembroke Power Station were:

ƒ Identify, obtain and check the information needed that describes the special conservation interest of the sites (provided by CCW) and the likely impact associated with the permit application (provided by the applicant); ƒ Establish the impacts of the proposed permitted activities by matching the predicted effects on the physical and chemical environment with the distribution of habitats and species known to be vulnerable to such changes; ƒ Establish the risk to these habitats and species by predicting the most likely changes in the extent and distribution of these habitats and species using a systematic checklist of tests based on known scientific knowledge; ƒ Determine if the predicted changes would compromise the conservation status of the habitats and species, using conservation objectives and criteria for favourable conservation status to inform that judgement; ƒ Ensure that the judgement took full account of the impacts of other activities already acting on the site and likely anticipated natural changes in the prevailing environmental conditions; ƒ Conclude, beyond all reasonable doubt and taking account of uncertainties and assumptions made, whether or not the impacts of the proposed permitted activity, acting alone or in combination with others, would adversely affect the integrity of the site i.e. the structure and ecological functioning of the site.

These steps and sources of information are summarised in Figure 3. Our overall conclusion was based on a sequential and systematic scrutiny of the predicted effects and likely ecological response. It should be noted that that in the case of this application the development of the AA was not straightforward, it was an iterative process with communication with CCW and Welsh Government following the latter issuing a Direction not to issue or refuse the EPR application.

- 22 - Figure 3 Summary diagram showing how the appropriate assessment was carried out and the sources of information and advice.

1d Information and how it was used

Sources of information and dealing with uncertainty

We ensured that we used best available information and expertise and applied it in an appropriate manner, using external peer reviewers with extensive knowledge of the character and ecology of Milford Haven to validate the way we arrived at conclusions. This included using extensive knowledge about estuarine ecology, dynamics and impacts of thermal and chemical pollution elsewhere to Pembroke. As with all ecological information, but particularly that involving estuarine and marine ecosystems which are relatively under-recorded and poorly understood, there is an unavoidable degree of uncertainty associated with available information. This uncertainty includes precision about: the distribution of habitats and species; natural trends and variation in this distribution; ecological response to individual and combinations of hazards and the level of acceptable risk from these hazards over space and time. Pembroke is not unusual in this respect and uncertainties associated with information and assumptions were addressed (beyond reasonable doubt) using expert judgement, realistic assumptions, best available scientific information and local specialist knowledge.

- 23 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 In all cases decisions were subjected to internal and external peer review. Expert judgement is of course open to challenge, but we reduced the risk of erroneous assertions by using external independent peer review by those with an international reputation and a detailed local knowledge of the site.

Determining those habitats and species potentially at risk

The distribution, extent, special requirements, vulnerability and threats associated with those habitats and species likely to be at risk from the proposed activities, were identified during an initial screening process and using information from CCW. The results of this Stage 2 likely significant effect process are shown in Table 1. We agreed with CCW that eight habitats (Atlantic salt meadows, coastal lagoons, estuaries, large shallow inlets and bays, mudflats and sandflats, reefs, sandbanks, and submerged sea caves), six animal species (grey seal, otter, river and sea lamprey, allis and twaite shad) and one plant species (shore dock) were potentially at risk. In reality there is considerable ecological overlap between the first five habitats as they all occur in Milford Haven as an array of inter-linked features. The conservation objective and the conservation status for each, where known, were used to establish the vulnerability of the habitats and species concerned. We used the conservation objectives that appear in the documentation supporting the site designation (CCW Regulation 33 Advice, April 2005). These were also used in the previous appropriate assessments supporting our Review of Existing Consents programme of work. This Regulation 33 Advice clearly states that ‘none of the information contained in this document legally binds any organisation (including CCW) to any particular course of action. However, in exercising their functions in accordance with the Habitats Directive the relevant authorities should be guided by the advice contained in this document’. This is what we have done. The conservation objectives are written as general statements of intent for the features of the site and are phrased in the following way: ƒ ‘to maintain at favourable conservation status its natural range and area covered, the structures and functions (of the habitat) necessary for its long-term maintenance and the conservation status of its typical species on a long-term basis; ƒ ‘to maintain at favourable conservation status (the species’) long-term population viability, natural range and the structure and function of its habitat within the site’.

We questioned CCW as to whether they consider wholly planktonic / pelagic species as 'typical species'. In their response (30th September 2011) they state that:-

‘Within the estuary, wholly planktonic / pelagic species will, as a minimum, represent estuarine predators or prey, affect the physical properties of the estuary such as turbidity, oxygen and nutrient availability and their presence could likely be predicted to occur at certain seasons/times. Most, though perhaps not every, wholly planktonic / pelagic species present within the estuary would be considered by CCW to be a typical species of the Estuary feature.’

- 24 - In April 2005 CCW published a list of criteria that it considered necessary to maintain or restore favourable conservation status for individual habitats and species. These ‘elements of favourable conservation status’ were also broadly constructed, such as: ƒ ‘the processes necessary for the long-term maintenance of…..should be.. - determined by natural processes…. - no more inhibited or degraded [although these statements were not quantified] as a result of human action than at the time of designation (i.e. as prevailing on 13th December 2004).

All the elements of favourable conservation status are listed in Appendix 1 of the Appropriate Assessment. The character of the site and nature of available information influenced the way we could use the data. Key factors included the following considerations:

ƒ Milford Haven is a complex, dynamic and intrinsically resilient ecosystem, subject to subtle changes over tidal, seasonal and longer-term time periods; ƒ There are no habitats or species unique to the site and the distribution of some features is uncertain; ƒ The assemblages of certain marine plants and animals is of particular interest primarily because of the unusually great extent of sub-tidal and inter-tidal rock in wave-sheltered but tidal stream exposed conditions, that extend into areas of variable salinity; ƒ There are a variety of complicated factors affecting the site, some of which are already causing concern because of deterioration in habitat quality resulting in a consequent assessment by CCW of ‘unfavourable conservation status’ within the site; ƒ There are a lack of quantified parameters that define what precisely (extent, quality, population size) favourable conservation status is, in relation to ecological functioning of the site; ƒ Consequently, there are no numerical thresholds representing the limits of acceptable and irreversible change leading to long-term failure of ecological functioning; ƒ Ecological changes due to increasing sea temperatures and also the spread of invasive non-native species are already occurring and cannot be reversed because it would be technically infeasible and prohibitively expensive; ƒ In many instances there is no research evidence to answer, with precision, the ecological responses to likely impacts; ƒ Several other activities within Milford Haven (e.g. dredging for navigation purposes) and surrounding land run-off affect the SAC and contribute to ‘prevailing environmental conditions’. Some of these activities are regulated by other organisations or not regulated at all; ƒ Measures to achieve conservation objectives and also ‘good ecological status’ for the European Water Framework Directive (2000/60/EC).

Establishing the likely potential effects/hazards caused by the proposed activity

Without the necessary detailed prescriptive management plan and numerical thresholds for favourable conservation status, trends and predicted future changes, we have had to use expert judgement to inform our decisions in the appropriate assessment. We increased our confidence in this expert opinion using external peer reviewers who have extensive knowledge of Milford Haven, its character and ecological trends.

- 25 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The consequences of the proposed activities (before and after taking account of mitigation measures) were determined by the applicant, working within the specifications of the proposed installations (abstraction and discharge structures) and existing Environmental Quality Standards. The physical and chemical consequences were described in some cases by computer- generated graphics and maps using scientific information (including our own monitoring and assessment data) to predict the type, location, extent and duration of effects. For example, this took account of tidal volume and currents in assessing the probable spatial and temporal pattern of chemical concentration and warm-water from the point of entry into Milford Haven. These computer-generated models illustrated likely conditions under different scenarios to account for extremes and typical conditions during tidal and seasonal cycles. Similar assessments were used to assess the cumulative impact of other activities affecting the SAC-such as thermal plumes associated with the Liquefied Natural Gas plant on the opposite side of the Haven to Pembroke Power Station. In each case the validity of the mathematical models and results were peer-reviewed internally and with Cefas before the results were used for decisions in the appropriate assessment. The key potential impacts (hazards) identified and agreed with CCW, as shown in Table 1 were: ƒ toxic contamination (chemical pollution); ƒ increased water temperature (thermal plume); ƒ an increase in plant nutrients (enrichment); ƒ habitat loss and physical damage; ƒ an increase in sediment loads (e.g. silt) and turbidity (opaqueness) of the water; ƒ smothering of plants (e.g. eel-grass) by excessive nuisance algal growth; ƒ entrapment/entrainment of fish by water abstraction; ƒ loss of plankton sucked in by water abstraction and killed by chemical treatment of the water.

The effects of these potential impacts needed to be considered alone and also in relation to each other to account for important cumulative and synergistic effects. We also took account of the cumulative effects of similar hazards acting alone and in combination elsewhere in the marine SAC.

Assessing the risk of individual hazards to habitats and species potentially at risk

Full details of the risk assessment procedures in our Appropriate Assessment method are described elsewhere (Environment Agency Operational Instruction 183_1, Habitats Directive: taking a new permission, plan or project through the Regulations). Given the complexities involved, our rationale, which is based on previous experience of complex cases (for example Mostyn Dock and Teeside ‘Ghost ships’) was to consider the effects of individual impacts on individual features first. This allowed us to establish a preliminary (‘alone’) conclusion about the likely effect of the activity (e.g. abstraction; thermal discharge, use of biocide for de-fouling) on the conservation status of the interest features exposed to the impacts and the integrity of the site.

- 26 - The risk to each habitat and species from a particular hazard was assessed by matching the overlap between the predicted effects and the distribution of habitats and species. Using the hazard as the starting point and assessing the consequences for habitats and species (rather than the other way round) provides a logical approach which is consistent with Environment Agency procedures for setting environmental quality standards. In reality, many impacts interact - either in a synergistic or compound fashion. These effects were dealt with by making realistic, peer-reviewed assumptions about for example: ƒ the combined effect of temperature on biocide toxicity and breakdown; ƒ the likelihood of increased water temperature on nutrient availability for increased algal growth. In simple terms, the test applied for assessing impact was:

‘Will the conservation objectives and favourable conservation status of those habitats and species for which the site is designated be compromised by:

ƒ a loss of habitat area; ƒ changes in the structure and biological communities living in the habitats; ƒ further impact on habitats already in unfavourable conservation status; ƒ disruption or degradation of the physical, chemical and biological processes needed to support the natural distribution of habitats; ƒ direct effects on species numbers; ƒ a reduction in the distribution of species below their expected natural extent; ƒ indirect effects (e.g. disrupted food chain, migration routes, habitat loss or degradation) on species?

The combination of the number of different hazards, habitats and species and using the questions above to assess whether conservation objectives and elements of favourable conservation status would be compromised, produced an exceptionally complex analytical matrix. Consequently, the Appropriate Assessment has been structured to allow our decision- making to be presented in a logical fashion. First, the possible physical, chemical and biological effects are explained in terms of the consequences of how an individual impact (e.g. toxic contamination) might lead to a change in condition within the site (e.g. directly affect the species population). Next, the most likely ecological response is established, taking account of the proximity, extent, duration, timing and intensity of the impact and the sensitivity, resilience of the habitat or species to that hazard. This provides an initial view on the likely spatial and temporal ecological impact of the hazard. Our initial conclusions about the risks posed by each activity to individual features, using the tests set out above, are presented individually in the Appropriate Assessment (e.g. Table 5.3) and the overall effect of each type of hazard to all the features at risk summarised in Table 5.23. The method of assessing the impact of the hazard on particular habitat or species took account of direct and indirect effects and also the ability of species to adapt behaviour, re- establish elsewhere or otherwise adapt to the changed conditions in the proximity of the hazard(s). Best available scientific information and local knowledge were used to establish the most likely biological response under worst-case and other scenarios.

- 27 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Reasons for concluding that the conservation objective for the habitat or species would not be compromised included: ƒ the habitat would not be significantly affected (i.e. its extent, structure and ecological functioning would not compromise the conservation objective because the effect is too far away or the predicted impact would affect too small an area to make any material difference to its character); ƒ the hazard can be avoided by adaptive behaviour (e.g. migratory fish); ƒ any localised effects would not be significant at the site level with respect to overall plant and animal community composition disrupting the natural dynamics in the estuary. For each feature and each hazard factor, the level of risk to the conservation status and achievement of the conservation objective was assessed. We did this by using a combination of generic scientific knowledge (e.g. known toxicity and thermal sensitivity of certain species), and applying realistic assumptions about the most likely ecological response agreed by our own scientists and ecologists, together with external peer-review. Appendix 1 of the Appropriate Assessment shows the results of how we considered conservation objectives and the ‘elements of favourable conservation status’ in our assessment, alone and in combination. We paid particular attention to the potential effects on those habitats and species in unfavourable conservation status and the reasons causing the failure(s). The reasons causing unfavourable conservation status as supplied by CCW were varied but the most relevant were habitat loss (either directly through erosion/removal or indirectly, through smothering of mudflats as a result of increased temperature and nutrients promoting excessive algal growth) and nutrient enrichment of the water and sediments, causing excessive algal growth. The prime example of this was ensuring that the level of nutrients available to plants entering the protected site from the process water was not increased. Cefas monitoring (Aldridge & Painting 2011)) highlighted that nutrients were resulting in excess algal growth within Pennar Gut, which were in turn smothering eelgrass beds, a typical species of the Estuary feature.

Assessing the cumulative effects of existing hazards elsewhere in the site

Our initial assessment (‘alone’) conclusions were then carried forward to take account of the potential cumulative effects of hazards already acting on the site (e.g. habitat loss from dredging, algal growth responding to nutrient input from the surrounding land, warm water input from other authorised thermal discharges etc). This is the ‘in combination’ technical part of the appropriate assessment process and the part that introduces added complexity in terms of the precision of available information, scientific understanding of interacting hazards and ecological response and also the institutional responsibility for dealing with the activities causing the hazards. The same procedure (i.e. checking the information; identifying the hazards; assessing the level of risk to each habitat and species to the cumulative hazards and assessing whether conservation objectives, favourable conservation status and overall site integrity would be affected) was repeated in accordance with our procedures (Environment Agency Operational Instruction 183-1, Habitats Directive: taking a new permission, plan or project through the Regulations; Document 220 04 SD01-Habitats Directive: appropriate assessment form for new applications).

- 28 - The key tests (in relation to conservation objectives and site integrity), risk assessment criteria and assumptions about ecological response to the hazards were all the same as described in paragraphs above, except that a much wider array of information had to be assembled for our overall conclusion to be reached (Figure 3). Internal and external peer review was used to challenge and confirm decisions. In order to fully consider the overall in combination effects, a summary of the effects appears as Table 6.12 in the appropriate assessment with Appendix 1 showing the result of our consideration of the ‘elements of favourable conservation status’. The in combination effects are discussed in the assessment in section 6.12.

1e Key factors determining our conclusion about adverse impact on site integrity

Key questions

Despite the immense complexity of the technical assessment process, the key questions for our overall conclusions were: ƒ How would the addition of warm water, at a rate of 40 cubic metres per second and treated with sodium hypochlorite biocide, directly and indirectly affect the physical structure of habitats and the ecology of associated plant and animal communities? ƒ How would the extraction of water and predicted entrainment of plankton and fish affect the dynamics of biological communities in the short and longer term, in particular the direct effects of recruitment and population dynamics of these features and also the direct effects on the food chain? ƒ How would the various effects interact and what cumulative impacts would be caused by interaction with other activities and pressures acting on the site? In assessing the likely effects against the conservation objectives, the key consequences, expressed in relation to site integrity can be summarised as:

ƒ Will the predicted scale, duration and timing of additional hazards exacerbate existing impacts influencing the prevailing environmental conditions and if so where, when and by how much? ƒ If anticipated effects potentially adversely affect the conservation status of special interest features will the ecological structure and functioning of those features (and therefore the initial intended contribution of the conservation site to the coherence of the Natura 2000 network and to maintaining favourable conservation status of the habitats and species) be compromised?

Important supporting questions were:

ƒ Will additional effects threaten the recovery of communities already in unfavourable conservation status (e.g. mudflats)? ƒ If there is an effect, how locally widespread will it be and how long will it last? ƒ Will the activity affect the conservation status of a special interest feature?

- 29 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 In accordance with the European Court of Justice case C127/02 (Waddenzee judgement), in order to conclude no adverse effect on site integrity we needed to be convinced, beyond reasonable doubt, that the hazards associated with new activities would not: ƒ compromise or undermine the conservation status of features (turning them unfavourable, or exacerbating unfavourable); ƒ undermine the conservation objectives as informed by the criteria (elements) of favourable conservation status; ƒ inhibit the recovery of habitats or species currently in unfavourable conservation status; ƒ undermine measures to return features to favourable conservation status.

The rationale for reaching our overall conclusion

The main test, given that the conservation objectives were crafted in similar broad terms to the UK Government definition of site integrity was: Would there, beyond reasonable doubt (as determined by available science, expert judgement and peer-review challenge), be no significant impact on the structure, functioning and natural extent of habitats and species for which the site was originally designated? Specifically, the evidence supporting a conclusion of ‘no adverse effect’ would have to demonstrate that any impacts would not: ƒ result in current causes of unfavourable conservation status to be exacerbated-and that the operation of the Power Station would not be a reason for habitats and species to remain in unfavourable status; ƒ compromise the long-term maintenance of conditions needed for the site to maintain its original contribution to the coherence of the Natura 2000 network and to the favourable conservation status of the habitats and species for which the site was designated.

- 30 - After taking all relevant factors into consideration during the appropriate assessment procedure and subjecting our assumptions and decisions to internal and external peer review our conclusion was informed by the following main reasons: ƒ The natural sediment dynamics of the tidal system would allow physical readjustment of habitat to localised physical disturbance caused by the water abstraction and discharge of water-and therefore not directly reduce by a significant amount the overall extent or structure of the habitats; ƒ There would be no net increase in the amount of biologically available phosphorus that causes excessive algal growth entering the system, through suitable mitigation; ƒ The volume and dynamics of the tidal currents would, through mixing and dilution, dissipate residual toxic effects to the extent that localised changes in species living in the sediments would not affect the overall extent of their distribution and ability to grow/reproduce/migrate; ƒ The effect of the thermal plume (and its cumulative effect on prevailing conditions such as nutrient levels and toxic chemicals) would not significantly affect the ecology of the water column; ƒ The ambient diurnal temperature range for inter-tidal habitats far exceeds the effects of the predicted thermal plume, so other than very localised effects near point of discharge, there would be no significant impact on the biological communities living in the sediment because they are well adapted to living in extreme conditions; ƒ Loss of fish through entrainment would not affect their overall populations and the loss of plankton would not be significant given the size of the site and fecundity (the potential reproductive capacity of an individual or population) of the species concerned. On this basis, we consider that the character and dynamics of the site and the natural resilience of the habitats and species in the ecosystem (e.g. the capacity of species to adapt to localised impacts, replenish their populations) would be able to compensate for predicted localised physical, chemical and temperature change and consequently not adversely effect the structure, and ecological functioning of the site. The detailed evidence and reasoning for making these assertions is included in the technical sections (chapters 4-6) of the appropriate assessment.

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1f Introduction summary

Our approach to the appropriate assessment demonstrates how: ƒ Conservation objectives and best available information have been used and best scientific methods and knowledge applied in making decisions and reaching a conclusion about the effects of the proposed activity on site integrity; ƒ All potential hazards have been identified and their effects, including cumulative effects, have been predicted to the best of our ability, through a comprehensive series of tests, and modelling assessments to remove any scientific doubt; ƒ These predicted effects were used to assess the most likely/probable impact on habitats and species for which the site was originally designated and the principle need to demonstrate beyond reasonable doubt that their conservation objectives would not be compromised; ƒ Reasonable and realistic assumptions were made about the nature and scale of impacts on the habitats and species in view of the dynamic natural processes within Milford Haven and the natural resilience of habitats and species occurring there; ƒ In the absence of numerical parameters defining the thresholds for determining site integrity, we used expert judgement, peer-reviewed decisions and realistic assumptions to reach an overall conclusion. ƒ We have been able to conclude no adverse effect on integrity of the European sites and to be convinced of that conclusion.

- 32 - 2. Application history

In April 2006 RWE npower submitted a Pollution, Prevention and Control (PPC) stage 1 application for the proposed Pembroke Power Station, which considered the effect of the cooling water discharge, specifically the change in thermal regime and toxic contamination due to the potential use of sodium hypochlorite biocide. The final version of the appropriate assessment concluded: “we would expect no adverse effect to the integrity of the Pembrokeshire Marine SAC or the Afonydd Cleddau Rivers SAC as a result of cooling water discharge from the currently proposed Pembroke power station. However, it should be noted that this conclusion does not take into account the potential effect of the abstraction of water from the Pembrokeshire Marine SAC or the in combination effects of the abstraction and discharge.” 6th June 2008 (edited Sep 2008 for clarity) Appropriate Assessment for the PPC permit (Pembroke Power Station). In March 2008 RWE npower submitted an application for a licence to abstract water from Pennar Gut for the purpose of non-evaporative cooling for the proposed power station. The final appropriate assessment concluded no adverse effect and the licence was granted on 22nd December 2008 (and varied to correct an administrative error on 8th February 2009). CCW disagreed with the conclusion to both of the above assessments. The abstraction intake design has now been completed to the standards specified by the Environment Agency to protect against the incidental entrainment and impingement of fish. Further details on this are discussed in section 6.11 of this appropriate assessment. The Department of Energy and Climate Change (DECC) granted a section 36 Electricity Act 1989 consent on 5th February 2009. As a result of the differences between CCW and the Environment Agency, and in order to find a way forward, at a meeting between Environment Agency Wales (EAW) and CCW (11th June 2009) it was agreed that as the assessment for the staged application had not resulted in the issuing of a permit, the process would be restarted with the submission of the application for the environmental permit. It was also agreed that both parties would meet before the application was submitted by RWE npower, and that both sides would work together in relation to agreed criteria, e.g. what is in the sensitivity matrix. Regular meetings and phone conferences were then held over the following months. This current application, to operate a combined-cycle gas turbine power station by RWE npower, was submitted on the 11th February 2010 and duly made on the 25th March 2010. As the applicant amended its proposal, during December 2010 to February 2011, for the PPS environmental permit, these changes prompted the Environment Agency to re-issue amended Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' form to CCW, so that all records were kept up to date. At each alteration, correspondence was sent to CCW, to keep them informed of the amendments. Confirmation was also sent, stating that all relevant components of the application were still being considered within the appropriate assessment.

- 33 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 3. How we have considered the views of the Countryside Council for Wales

As mentioned in section 2, because the Countryside Council for Wales (CCW) disagreed with our conclusions for both of the previous assessments, a meeting was held on the 11th June 2009. CCW and the Environment Agency (EA) agreed to work together throughout the determination of RWE’s permit application for the power station, particularly to agree an approach to assessing the potential impact of the project on the European sites. An important part of this process was the development, by CCW, of what has been described as a ‘sensitivity matrix’ (Appendix 3), devised in order to show the potential impacts on the SAC features. We agreed to use the sensitivity matrix to determine potential impacts, consider the site’s Conservation Objectives (COs) in our decision-making and finally reconsider, at the in combination stage, effects of other permits, plans and projects that may have been screened out at the likely significant effects stage of the assessment. It was also important to gain a common understanding of all available information and if there was a difference of opinion, we agreed to try to understand and resolve these differences. In November 2009, as part of the pre-application discussions for the permit, a meeting took place between CCW, the EA and RWE npower (RWE). We discussed: environmental assessment, water quality modelling and a draft list of plans and projects to be taken into account for the in combination assessment. This meeting was in addition to another meeting that took place between the CCW and EA at that time. During the determination of this application we have continued to work to the process agreed between us and CCW. In April 2011 we consulted CCW on our draft Appropriate Assessment and met with CCW staff during the consultation period to discuss their concerns regarding the project. As a result of this meeting a further iteration of the Appropriate Assessment was undertaken. Subsequently, but still within the consultation period, we provided a further iteration of our draft Appropriate Assessment which, to the extent that this was possible, responded to and sought to accommodate, the concerns raised by CCW. Despite these on-going discussions in May 2011, CCW responded to the consultation of the Appropriate Assessment setting out in clear terms its opposition to the draft conclusions of the Appropriate Assessment. After further meetings with CCW in October 2011, they have maintained their position.

Summary of CCW's concerns.

CCW’s main concern is that the project will result in substantial adverse impacts on the habitats and species for which the conservation site was designated as a SAC, and that these impacts will prevent the site from meeting its conservation objectives, which in turn CCW use to determine whether the site is in Favourable Conservation Status (FCS). Therefore, because CCW believe this project will prevent the conservation site from achieving FCS, they advise that this project will have an adverse effect on site integrity.

What we have taken into account in addressing those concerns and what if anything we have changed.

CCW's view appeared to be that each of the elements of favourable conservation status relating to the components of the designated features’ COs must be met in their entirety, otherwise FCS will not be maintained or restored, leading to an adverse effect on site integrity. However in recent letters CCW has advised that in some cases, COs will not be met, but the duration and scale of those cases are such that they can be considered trivial, and thus in the long term there will not be an adverse effect on the integrity of the site.

- 34 - Although the Environment Agency accepted that the project will mean that some elements of favourable conservation status relating to individual components of the COs may not be met, the findings of our detailed assessment lead us to conclude that this will not affect the integrity of the SAC overall as outlined in section 1. CCW’s phrasing of these elements means that no project other than a remedial project could be authorised without failing to meet the individual elements of favourable conservation status. In this regard, the Agency's approach to the Article 6(3) test under the Habitats Directive focuses on the effect on site integrity resulting from individual components not being met, rather than simply on whether each individual component is met. We believe that approach to be correct. In the course of correspondence between the Environment Agency and CCW concerning this appropriate assessment, CCW appeared to accept the Environment Agency’s approach as the relevant legal test. However, CCW continued to disagree with the Environment Agency’s conclusions on the application of that test. Mindful of CCW’s concerns, the Agency has sought to impose strict limits and measures regarding the operation of the power station for the protection of the natural environment. Such measures will, for instance, include: ƒ A limitation on the abstraction rate of 40 cubic metres per second and continuous monitoring of this by the Environment Agency. Abstraction rates would be subject to inspection by the Environment Agency; ƒ The installation of four drum screens, a fish recovery system and acoustic and strobe light fish deterrents; and ƒ A requirement to test the effectiveness of the above measures and agree the effectiveness in writing with the Environment Agency before any abstraction takes place; ƒ Nutrient mitigation to result in a net reduction in phosphate within Pennar Gut. In the context of the draft Environmental Permit we have proposed: ƒ A thermal limit on the discharge; ƒ A limit on the concentration of residual oxidant (biocide) in the discharge that is significantly below indicative BAT; ƒ Limits on the concentrations of other substances such as nutrients and metals in the process streams that make up the discharge; ƒ A requirement to undertake an additional monitoring programme (in addition to the extensive monitoring already conducted) to determine the physical, chemical and biological characteristics of the area, once operation has begun, that could be affected by the discharge and a procedure for assessing any effect and reporting the results of the monitoring; ƒ The requirement to cease discharge if phosphate mitigation is not in place by the 1st May 2012. We believe that these, and other restrictions and measures on the operation of the power station ought to allay any residual concerns there may be regarding the authorising of this project.

- 35 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The protection of Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers Special Area of Conservation (SAC), as well as the other sites considered at Stage 2, is of the highest priority to the Agency. In determining RWE’s permit application we believe we have correctly applied the strict legal test contained in the Habitats Directive, the test being one that accords with the purpose of the Directive. The Agency is satisfied that the project will not adversely affect the integrity of the SAC. Moreover, the findings of the Appropriate Assessment lead us to conclude that the factors currently causing unfavourable conservation status would not be exacerbated by the operation of this power station. We have, however, conducted a thorough review of this appropriate assessment following our consultation, and in the light of CCW’s concerns, to ensure that our reasoning is fully transparent, and our conclusions robust. What remains an issue and why for the process.

One outstanding issue remains with the overall process. CCW takes the view that Favourable Conservation Status (FCS) and fulfilment of each component of FCS set out their Regulation 33 (April 2005) advice that has been included in the site’s Conservation Objectives (COs), are virtually synonymous. It is CCW's view that FCS of SAC features, as defined by the site’s COs, will not be met as a result of the foreseeable consequences of the project. The Agency, on the other hand, accepts that some individual elements of FCS relating to the conservation objectives will not be met as a result of the project. However, we do not consider that this will adversely affect integrity of the site. For the reasons set out in this assessment we have concluded that factors currently causing unfavourable conservation status would not be exacerbated by the operation of this power station. Despite concerted attempts, CCW and the Agency have been unable to agree on the correct approach to the appropriate assessment for the site. However, the Agency has given careful consideration to CCW's views. The earlier appropriate assessments set out the areas of disagreement between the parties and those are dealt with in greater detail in the minutes of the meetings referred to above, which sought to resolve areas of dispute. The Agency has not only had due regard to CCW’s concerns in arriving at its conclusions, but has also actively taken steps to resolve the areas of dispute where possible. The fact that the Agency has been unable to reach complete agreement with CCW on the assessment of impacts on the site is regrettable. However, the Agency is satisfied that it has had proper regard to the concerns raised by CCW during the course of this assessment and permit determination. A decision under UK legislation regarding any appropriate assessment is one for the competent authority to make, having had regard to the advice of the nature conservation body.3 Ultimately, the decision is one for the Agency and, after careful consideration, the Agency has concluded that the permit should be granted, and that doing so is compatible with the Habitats Directive. The additional concerns from CCW with regard to the environmental risks posed by the proposed EPR permit can be found within Annex III.

3 See regulation 61(3) of the Conservation of Habitats and Species Regulations 2010 - 36 - 4. Individual feature summary

The Pembrokeshire Marine SAC is the third largest marine SAC in the UK (138,069 ha) as shown in Figure 1. The SAC extends from just north of Abereiddy on the north Pembrokeshire coast to just east of Manorbier in the south. It includes the coast of the islands of Ramsey, Skomer, Grassholm, Skokholm, the Bishops and Clerks and The Smalls. It also encompasses almost the entire Milford Haven waterway. The landward boundary of the SAC mostly follows the extreme high water mark. The Pembrokeshire Marine SAC site was proposed in 1995 (then called Pembrokeshire Islands). In 1997 the site was submitted to the European Commission, and then, along with all other candidate SACs in Wales, was formally designated in December 2004.

Coastal habitats sensitive to abstraction

Coastal lagoons

Coastal lagoons are areas of typically shallow, brackish or saline water, wholly or partially separated from the sea by sandbanks, shingle or occasionally rocks. They retain a proportion of their water at low tide which can be brackish (diluted slightly by freshwater), fully saline or hyper-saline (more salty than seawater due to evaporation). There are three saline lagoons around the Milford Haven waterway. Figure 4.1, shows that the lagoon features are widely distributed around the estuary. All are naturalised impoundments, formed by artificial structures. Occasionally, management action is taken to maintain the impoundment structures. The extent of the lagoons are primarily determined by the morphology of the estuary banks and the artificial impoundment structures. Pickleridge Lagoon and Carew Mill Pond are subject to slow sediment accretion. Neyland Weir Pool is subject to encroachment by salt meadow, possibly accelerated by suspended sediments.

Figure 4.1: Location of the coastal lagoon priority feature.

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The conservation objective for the coastal lagoons feature is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis4. The conservation status of the coastal lagoon feature was described as favourable: maintained by CCW in 20065.

Estuarine and intertidal habitats

ƒ Estuaries ƒ Atlantic salt meadows (Glauco-Puccinellietalia maritimae) ƒ Large shallow inlets and bays ƒ Mudflats and sandflats not covered by seawater at low tide

Estuaries

Estuaries are complex and highly productive ecosystems, supporting a wide range of habitats and species. They provide an essential migratory route for fish species making the transition between the marine and freshwater environments, extending from the upper limit of tidal influence to the open sea. In addition these habitats are used extensively as a nursery and feeding ground for fish species such as bass and flounder. The location map (figure 4.2) shows how the estuaries feature is distributed around the Milford Haven waterway. Pembrokeshire Marine SAC includes the Daugleddau estuary and is associated with a wide range of environmental conditions, particularly seabed substrates, tidal streams and salinity gradients, creating a diverse array of communities and species. The species-richness of sediment communities throughout Milford Haven and the Daugleddau is high. Tide-swept sponge communities on shell/cobble substrates and bedrock in the upper reaches of the Daugleddau are exceptionally diverse. The site also includes smaller estuaries entering the Daugleddau and Milford Haven and wide intertidal mudflats with rich and productive invertebrate annelid and mollusc communities, occurring in ‘pills’. The conservation objective for the estuaries feature is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for their long-term maintenance, and the conservation status of their typical species on a long-term basis6. The conservation status of the estuaries feature was described as unfavourable: declining by CCW in 20065.

4 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. 5 Conservation status from: Pembrokeshire Marine SAC Habitats Directive Article 17 table, CCW 2006. 6 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 38 -

Figure 4.2: Location of estuaries feature.

Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

Atlantic salt meadows develop when salt-tolerant vegetation colonises intertidal sediments of mud and sand in areas protected from strong wave action. This vegetation forms the middle and upper reaches of saltmarshes, where tidal inundation occurs with decreasing frequency and duration. The salt meadow is distributed intermittently throughout the Milford Haven waterway, with the largest areas within the tributary estuaries (see figure 4.3). There was an estimated 173 hectares of saltmarsh within the site recorded in 2002. The conservation objective for the Atlantic salt meadows feature is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis7. The conservation status of the Atlantic salt meadows feature was described as unfavourable: unclassified by CCW in October 20065.

7 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 39 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Figure 4.3: Location of Atlantic salt meadows feature

Large shallow inlets and bays

Large shallow inlets and bays are large indentations of the coast, generally more sheltered from wave action than the open coast. They are relatively shallow (with water less than 30 m over most of the area), and in contrast to estuaries, generally have much lower freshwater influence. The Milford Haven waterway, within the Pembrokeshire Marine SAC, is one of the best examples of a ria8 in the UK, with wide, shallow, predominantly sandy embayments9 of St Brides Bay. See figure 4.4 for the indicative extent of the large shallow inlets and bays feature. The wide range of environmental conditions, particularly seabed substrates, tidal streams and salinity gradients, supports high community and species diversity. The species richness of sediment communities throughout Milford Haven, is particularly high with intertidal sandy/muddy areas supporting extensive beds of narrow-leaved eelgrass Zostera angustifolia. High-salinity water and rocky substrates penetrate far upstream, with communities characteristic of fully saline conditions. A wide range of subtidal and intertidal rocky habitats are present, from rocky reefs and boulders to rich underboulders, crevices, overhangs and pools.

8 Ria: A drowned river valley in an area of high relief; most have resulted from the post-glacial rise in relative sea level. 9 Embayment: A type of marine inlet where the line of the coast typically follows a concave sweep between rocky headlands, sometimes with only a narrow entrance to the embayment. - 40 - A particular feature of rias is the presence of sublittoral rock in conditions of strong tidal flow but negligible or no wave action. Particular growth forms of sponges and ascidians, as well as specific biotopes, occur in these unusual conditions. In tide-swept areas communities of hydroid and bryozoan turfs or beds of brittlestars may be dominant. Beds of horse mussel Modiolus modiolus characterise some seabeds. Animal-dominated sediment communities range from gravels and coarse sands dominated by burrowing sea cucumbers, large bivalves and heart-urchins, through finer sediments supporting communities of polychaetes and small bivalves, to fine muds with beds of sea-pens, large burrowing crustaceans and bottom-dwelling fish. The conservation objective for the large shallow inlets and bays feature is to maintain favourable conservation status of its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis10. The conservation status of the shallow inlets and bays feature was described as 5 unfavourable: declining by CCW in 2006

Figure 4.4: Location of large shallow inlets and bays

10 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 41 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Mudflats and sandflats not covered by seawater at low tide.

Intertidal mud and sand-flats are habitat types that vary considerably throughout the site. This is primarily due to local conditions of coastal topography, shore morphology, exposure to water movement, sediment processes and salinity regime. The resultant intertidal mudflats and sandflats characterise a range of different environmental conditions, which are distributed throughout embayments, inlets and estuaries within the site. Sediment flats in open coast bays are both extensive and restricted to the mid to lower shore by rock features at the base of cliffs. Flats in more sheltered bays, inlets and estuaries range from ‘pockets’ of sediment restricted by coastal geomorphology to extensive mud flats fringing inlets and estuaries. See figure 4.5 for the indicative extent of this feature. Sediment flats within Milford Haven waterway are accreting slowly in places but expansion is curtailed by channel structure throughout much of the waterway. Extent has also been reduced through intertidal land claim, shoreline development and possibly indirectly modified as a consequence of channel dredging. The conservation objective for the mudflats and sandflats not covered by seawater at low tide feature, is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis11. The conservation status of the mudflats and sandflats not covered by seawater at low tide habitat was described as unfavourable: declining by CCW in 200615.

Figure 4.5: Indicative location of mudflats and sandflats feature

11 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 42 - Submerged marine habitats

ƒ Reefs ƒ Sandbanks which are slightly covered by seawater all the time ƒ Submerged or partially submerged sea caves

Reefs Reefs in this South-West Wales site are largely composed of igneous rock but include areas of more friable Old Red Sandstone and some limestone. Extensive areas of sublittoral rocky reef stretch off-shore from the west Pembrokeshire coast and between the Pembrokeshire islands and many small rocky islets. Limestone reefs occur in the south of the site. Reefs also extend through Milford Haven and into the variable salinity conditions of the Daugleddau estuary. Reefs within the site are subject to an exceptional variation in strength of tidal streams and wave exposure. The highly variable rocky seabed topography, together with the indented coastline and extreme tidal range can cause strong tidal streams, particularly around headlands, through sounds and in tidal inlets. The shallower and south-west-facing rocky reefs are exposed to severe wave action, while many others are extremely wave-sheltered. Many of the reefs extend onto the shore and provide examples of both the most exposed and the most sheltered intertidal rock communities in southern Britain. Reef habitat diversity is increased by caves, tunnels and surge gullies in both subtidal and intertidal zones. The wide variation in exposure to water movement, the range of rock type, slope, aspect and topography, and the high water quality, together with local exposure to abrasion from adjacent sediments and reduced salinity in the Daugleddau, are reflected in the wide diversity and species abundance of biological communities. See figure 4.6 for the extent of this feature. Off-shore there are particularly extensive areas of tide-swept kelp and species-rich red algal populations. Across the large areas of deeper rock reef, there is a wide range and abundance of invertebrate animal communities, with hydroid, bryozoan, soft coral and anemone species. More sheltered reefs, including those in lowered salinity and higher turbidity, typically support diverse and species-rich sponge and ascidian-dominated communities. The conservation objective for the reefs feature is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long- term maintenance, and the conservation status of its typical species on a long-term basis12. The conservation status of the reef feature was described as unfavourable: no change by CCW in 2006.

12 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 43 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 4.6: Indicative location of reef feature

Sandbanks which are slightly covered by seawater all the time

Sandbanks are distributed throughout the site, typically associated with headlands, islands, islets or sublittoral reefs which modify tidal streams to favour sandbank establishment and maintenance, but include the southern part of a major offshore linear sandbank. The depth ranges in which the banks are distributed vary significantly, resulting in a diversity of bank structure, function and species. The major known sandbanks include: • Bais Bank • Turbot Bank • Sandbanks in the vicinity of Skokholm (Wild Goose Race & The Knoll) • Sandbanks associated with Grassholm Island There are also deeper sandbanks associated with the Bishops & Clerks, Hats & Barrels and St Govan’s Shoals reefs and in NW and SW St Bride’s Bay. The diversity and types of community associated with this habitat are determined particularly by sediment type together with a variety of other physical, chemical and hydrographic factors. These include geographical location (influencing water temperature), the relative exposure of the coast (from wave-exposed open coasts to tide-swept coasts or sheltered inlets and estuaries), the topographical structure of the habitat, and differences in the depth, turbidity and salinity of the surrounding water. See figure 4.7 for the indicative extent of this feature.

- 44 - The conservation objective for the ‘sandbanks which are slightly covered by seawater all the time’ feature, is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis13. The conservation status of the sandbank feature was described as unfavourable: no change by CCW in 20065.

Figure 4.7: Indicative location of sandbank habitat feature

Submerged or partially submerged sea caves Distribution of sea caves with an intertidal element within the site, is generally well known but is poorly documented or mapped. The majority of known sea caves are at or close to interfaces between sea – land and/or rock – sediment, where marine erosion processes are most intense. There are likely to be many additional caves that have remained undetected because of the small size, or inconspicuous or inaccessible entrances. Discarded and misplaced artificial materials are present in many sea caves. Lost and discarded fishing equipment and persistent rubbish, form a physical hazard to many species and some are a source of chemical contamination. Caves demonstrate a tendency to retain debris, particularly those caves with complex shapes and/or boulder/cobble floors. Quality of sea cave habitat is of particular importance to grey seals which utilise caves as resting haul-out and breeding sites. See figure 4.8 for the extent of this feature.

13 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 45 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The conservation objective for the sea caves feature is to maintain at favourable conservation status its natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of its typical species on a long-term basis14. The conservation status of the sea caves feature was described as favourable by CCW in 20065.

Figure 4.8: Indicative location of sea caves feature

Coastal Plants

Shore dock (Rumex rupestris)

Shore dock is one of Europe’s most threatened endemic vascular plants. It is currently known to grow in 38 locations in south-west Britain, of which very few are in Wales (Plantlife, 2002). This species is described as one of the world’s rarest docks and has greyish leaves and tiny green or reddish-brown flowers in whorls spread out up the stem. In the UK Rumex rupestris is now found at only 38 sites in Cornwall, south Devon and Wales. Its distribution may be limited by climatic factors such as annual rainfall or number of frost days. It is also possible that a key factor limiting distribution is the direction of ocean and coastal currents. See figure 4.9 for the location of this feature.

14 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 46 - Rumex rupestris occurs in a small number of closely related coastal habitats, and only rarely now in dune slacks. Fundamentally, Rumex rupestris occurs within a relatively narrow zone above high water mark, in the presence of freshwater, often where dynamic processes of coastal erosion constantly create bare ground. It is able to withstand considerable salt deposition from sea spray and may be able to survive short periods of inundation during winter storms (King, 2003). The conservation objective for the shore dock feature is to maintain at favourable conservation status its long-term population viability, natural range and the structure and function of its habitat within the site15. The conservation status of the shore dock feature was described as favourable: maintained by CCW in November 20065.

Figure 4.9: Location of shore dock

15 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 47 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Marine mammals

Grey seal (Halichoerus grypus)

The grey seals around the West Wales coast are one of the most southerly breeding populations in Europe of one of the least common seal species. The seals utilising the area of the Pembrokeshire Marine SAC comprise the major proportion of an isolated breeding population, in which the breeding ecology differs from that of grey seals elsewhere. The West Wales population size, as determined by pup production estimates, is approximately 5000 individuals. Grey seals breed on undisturbed beaches of cobble and boulders, and on cobble beaches within sea-caves along the coast (Pembrokeshire Marine Management Scheme, 2008). As highly mobile predators, seals are widely distributed within, and beyond, the SAC. Figure 4.10 the indicative extent of this feature. For much of the year, seals are widely dispersed and may be seen almost anywhere along the West Wales coast, even in rivers at times. Studies have shown that young seals from the Pembrokeshire colonies are great wanderers, reaching north into Liverpool Bay, south to Devon and Cornwall, to Brittany and even the north coast of Spain, while others have crossed to Ireland even as far as Galway Bay on the west coast16. Only their pupping and regular moulting sites may be determined with precision. Sand eels and cod are the most important foods in the diet of the grey seal, but they are opportunistic feeders and probably take whatever fish are most abundant17. As a top predator, seals are prone to accumulation of contaminants present within their food chain particularly those that are persistent and those that tend to bioaccumulate and biomagnify. The conservation objective for the grey seal (Halichoerus grypus) feature is to maintain at favourable conservation status its long-term population viability, natural range and the structure and function of its habitat within the site18 The conservation status of the grey seal feature was described as favourable: maintained by CCW in 20065.

16 Web link: www.welshwildlife.org/greyseals 17 Web link: www.mammal.org.uk 18 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 48 - Figure 4.10: Indicative location of grey seals and distribution of grey seal pupping sites.

Anadromous fish

ƒ Allis shad (Alosa alosa) ƒ Twaite shad (Alosa falax) ƒ Sea lamprey (Petromyzon marinus) ƒ River lamprey (Lampetra fluviatilis)

It is stated in CCW’s Regulation 33 (April 2005) advice that ‘Milford Haven waterway encompasses, wholly or in part, several Annex I habitats and contributes to supporting the presence of several Annex II species in the site’. However, of the anadromous species, only river lamprey and sea lamprey are listed as being supported by the Milford Haven waterway (Lee-Elliott & Birkett, 2008). The Cleddau Rivers SAC comprises two river catchments, the Western and Eastern Cleddau and selected tributaries which join to form the tidal reaches of the Daucleddau; part of Pembrokeshire Marine SAC. Cambell el. al. (2005) undertook a monitoring programme which recorded the presence of river lamprey in the Cleddau but noted that the river was failing its target on the basis of low mean density within optimal habitat requirement. However, when considered from a catchment wide perspective, where both optimal and sub-optimal habitat are taken into account, recorded densities and population structures for the catchment reached the required target under the LIFE in UK Rivers condition assessment, although, not under the JNCC Common Standards Monitoring guidelines. In contrast recent surveys have not found evidence of sea lamprey within the Cleddau catchment.

- 49 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Shad is not a feature of the Afonydd Cleddau SAC as they are not known to spawn in the Cleddau catchment. It is thought they utilise the open coastal waters of the marine SAC as an area of growth and maturation prior to their migration to the Tywi river, where they are known to spawn. Sea and river lampreys spend their adult life in the sea or estuaries but spawn and spend the juvenile part of their life cycle in rivers. Both species of shad are vulnerable to fishing (as a bycatch), pollution, and to obstructions to migration within the river (especially as their strong shoaling behaviour and intolerance of strong turbulent conditions mean that they are reluctant to use fish passes). The allis shad may be particularly vulnerable to migration obstructions as they tend to spawn further upriver than the twaite shad19.

Lamprey

Lampreys are primitive fish that have a distinctive suckered mouth, rather than jaws. Sea and river lampreys spend their adult life in the sea or estuaries but spawn and spend the juvenile part of their life cycle in rivers. There are known populations of river lamprey within the Cleddau rivers catchments, however, recent surveys have found no evidence of sea lamprey. The Regulation 33 advice states that both species must pass through both the open coast waters and Milford Haven waterway to access the rivers systems. Very little is known about the migratory trigger for lamprey, however it has been suggested that migratory and spawning behaviour may be temperature dependent (Maitland, 2003). Sea lamprey also require sustainable river flows and generally favour larger streams and rivers with a minimum depth usually between 0.1 to 0.5m20. The conservation objectives for river lamprey (Lampetra fluviatilis) and sea lamprey (Petromyzon marinus) features are to maintain at favourable conservation status their long- term population viability, natural range and the structure and function of their habitats within the SAC21. The conservation status of the sea lamprey feature was described as unfavourable: declining by CCW in 200625. The conservation status of the river lamprey feature was described as unfavourable: no change by CCW in 20065.

Shad

Shad are herring-like fish that spend most of their adult lives in the sea but spawn in rivers, or occasionally in the upper reaches of estuaries. They usually migrate through estuaries in spring months on their way to spawning grounds. There are few records of shad within the Pembrokeshire Marine SAC, and data is still required to confirm whether these species are indeed still present within the SAC, and if they are breeding. The migration of shad is strongly correlated with water temperature and inversely correlated to flow. Both allis shad and twaite shad must spend part of their life cycles in the sea and in the rivers, and the successful maintenance of the populations is dependent on both freshwater recruitment and their migrations to and from the feeding areas in the sea. The conservation objectives for the allis shad (Alosa alosa) and twaite shad (Alosa fallax) features, are to maintain at favourable conservation status their long-term population viability, natural range and the structure and function of their habitats within the SAC.

19 Web link: www.pembrokeshiremarinesac.org.uk 20 Habitat & Species summary guidance notes, Sea Lamprey (Petromyzon marinus), ATKINS.

21 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, 2005. - 50 - The conservation status of the allis shad and twaite shad features have not been assessed, therefore the status is unknown, as reported by CCW in 20065.

Mammals of riverine habitats

Otter (Lutra lutra)

Otter (Lutra lutra) historically existed throughout most of the UK. They can be found on estuaries and open shores, but they do rely on being close to freshwater for the majority of their food, to wash salt water from their fur and to provide suitable habitat for resting and building holts. A combination of protective legislation and improvements in water quality have seen a marked increase in the UK otter population since the mid 1980s, in both range expansion and increased abundance22. Otters are highly adaptable semi-aquatic carnivores capable of foraging in both freshwaters and marine environments and are thought to be opportunistic foragers taking prey groups roughly according to their availability (Kruuk, 2006). They have a varied diet including salmonid fish, crayfish, eels, toads and young birds. A report by Parry (2008), discovered the diet of otters predominantly included gobies, blennies and eels. Persecution, habitat loss, drainage and pollution of waterways led to a drastic decline of otter numbers during the 1950s and 60s. At present the UK otter population, important for its genetic diversity, has made a marked increase since the mid 1980s due to improving river water quality and favourable land management methods. Figure 4.11 shows the extent of this feature. In Wales, potential resting sites on the coast and in estuaries include reed beds (for example, Oxwich Bay on the Gower, and the River Teifi estuary), tree root systems and scrub (Liles, 2003). Distribution of spraint records and reported sightings show that otters are frequently found throughout Pembroke Marine SAC, both on the open coast and in the Milford Haven waterway and local rivers. They are most frequent at places where there is good access to the sea, sufficient tree and scrub cover, near streams where salt water can be washed off, and good feeding locations such as rock pools. The conservation objective for the otter (Lutra lutra) feature is to maintain at favourable conservation status its long-term population viability, natural range and the structure and function of its habitat within the site23. The conservation status of the otter feature was described as favourable by CCW in 20065.

22 www.otterproject.cf.ac.uk 23 A summary of the conservation objective for the European site is given above and for each of the features in this section, a more detailed description can be found in the Regulation 33 advice for Pembrokeshire Marine SAC, CCW, April 2005. - 51 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 4.11: Indicative location map of otters

Overall conservation status

The conservation status of each feature and habitat, described within Section 4, has been agreed with CCW and is based on best available information to date, as supplied to the Environment Agency.

Table 4.0 – Conservation status summary Feature Conservation status Coastal lagoons (Priority species) Favourable: maintained (CCW 2006) Estuaries Unfavourable: declining (CCW 2006) Atlantic salt meadows (Glauco-Puccinellietalia maritimae) Unfavourable :unclassified (CCW 2006) Large shallow inlets and bays Unfavourable: declining (CCW 2006) Mudflats and sandflats not covered by seawater at low tide. Unfavourable: declining (CCW 2006) Reefs Unfavourable: no change (CCW 2006) Sandbanks which are slightly covered by seawater all the time. Unfavourable: no change (CCW 2006) Submerged or partially submerged sea caves Favourable (CCW 2006) Shore dock (Rumex rupestris) Favourable: maintained (CCW 2006) Grey seal (Halichoerus grypus) Favourable: maintained (CCW 2006) Allis shad (Alosa alosa) Unknown (CCW 2006) Twaite Shad (Alosa falax) Unknown (CCW 2006) River lamprey (Lampetra fluviatilis) Unfavourable: no change (CCW 2006) Sea lamprey (Petromyzon marinus) Unfavourable: declining (CCW 2006) Otter (lutra lutra) Favourable (CCW 2006)

- 52 - 5. Technical assessment

5.1 Toxic contamination - Sodium hypochlorite biocide (Chlorination agent)

This assessment follows the key steps shown below:

5.1.1 Biofouling control and mitigation

RWE npower (RWE) state that, in the absence of appropriate control measures, the cooling water system would be at substantial risk of suffering biological fouling (biofouling) as a consequence of the entrainment of organisms into the system. Biofouling is generally of two types: macrofouling (e.g. mussels) and microfouling (e.g. bacteria, fungi and algae). Biofouling has potentially serious consequences for the operation and the environmental performance of the plant, ranging from reduced thermal efficiency (and hence greater emissions per unit of power generated) to condenser tube blockages and failures, and plant outages in order to repair damage. The application from RWE has looked at achieving biofouling control through a combination of intrinsic design of the plant, mechanical and chemical measures. Design and mechanical measures will be employed, but alone will not provide sufficient operational reliability; hence they are looking at supplementing it with chemical measures. It is proposed to use the oxidant sodium hypochlorite for biofouling control. To minimise the use of hypochlorite dosing, and hence its potential environmental impact, it is proposed by RWE: ƒ to dose during the mussel growth season from April to December inclusive24; ƒ to split the flows through the system and dose separately and in sequence such that the dosed section flow, combines with flow from undosed sections to provide dilution prior to the discharge into the Haven; and ƒ not to dose the culverts leading to the cooling water discharge, so that the residual concentration of biocide in the water flow from the condensers would be further reduced by decay and by reaction with organic material in the outfall culverts prior to discharge to Milford Haven waterway.

24 Document ENV/451/2011 – First order decay modelling of the TRO plume from Pembroke CCGT cooling water discharge. - 53 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 RWE have provided further clarification relating to the dosing of the drum screen chambers, (refer to document dated 23.03.201125). Chemical dosing with sodium hypochlorite will be optimised by considering the potential for: ƒ non-continuous dosing of individual system components; ƒ opportunities to combine the discharge stream of chlorinated condensers with those of non-chlorinated condensers26. It is proposed by RWE, that only part of the cooling water system would be chlorinated at any one time. The combination of non-chlorinated and chlorinated cooling water streams prior to discharge would be expected to result in a rapid reduction of oxidant concentrations. The final modelled discharge will be no more than 50 μgl-1 of Total Residual Oxidant (TRO) expressed as chlorine27. Dosing with sodium hypochlorite will occur at the entrance to each pump house chamber (of which there are two) and then between the pump house chamber and the CCGT units (of which there are five). The fish return pumps (which draw water from the pump house chambers) will not be operated whilst dosing of the pump house chambers occurs. Additionally, facilities will exist for the manual dosing of incoming cooling water at the inlet to each of the four drum screen chambers as these facilities will themselves need dosing. It should be noted that although the manual dosing points at each drum screen chamber are upstream of the fine screening provided by the drum screens they are downstream of the point of initial (coarse) screening. Dosing upstream of the coarse screens is not proposed because it would give rise to a risk that some of the hypochlorite might not be carried into the intake and we would not consider such an approach to be BAT32.To prevent water dosed with sodium hypochlorite being pumped into the fish return system during dosing of the drum screen bays, the drum screen will be stopped from rotating and the pump for the fish return system and debris removal shut down, before the drum screen chamber dosing sequence starts28. The drum screen dosing sequence will only be capable of being initiated manually at the cooling water intake. On the 17th January 2011, RWE submitted a report with revised TRO29,30modelling, in which RWE state that they are not able to lower the emissions further than 50 μgl-1 at the point of discharge. This revised model has since been verified and confirmed fit for purpose by the EA’s specialist marine team:

‘The improved TRO modelling reported by RWE npower in January 2011 is a clear extension of the tracer results presented within the Environmental Permit application. Laboratory results for TRO decay in water from Milford Haven are judged alongside literature values to select a first-order decay rate. Outputs include a sensitivity test, and enough data for this present report to infer the extent of the EQS (10µg/l 95 percentile) footprint. As such this TRO modelling is accepted as fit for purpose31’.

25 Environment Agency letter reference 22/61/6/156 26 Appendix 2.3, Cooling water system vulnerability to bio-fouling. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 27 Part II, Chapter 7 – Ecological Effects of Operational Physical Marine Changes, pg 48. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 28 Part I, Chapter 2 – Project Description pg 18. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 29 In saline waters, chlorine or hypochlorite are measured as Total Residual Oxidant (TRO). This is the sum of all oxidants including chlorine, bromine, hypochlorite, hypobromite, cloramines and broamines. 30 RWE, 2011. First order decay modelling of the TRO plume from Pembroke CCGT cooling water discharge, ENV/445/2011. 31 EA Southern Region Marine Team. Report 10289. Final with update 24 April 2011. Pembroke Power Station – Cooling Water Discharge (thermal and TRO impacts). - 54 - 5.1.2 The fate of chlorine in salt water

The reactions of chlorine in salt water are very complex, due to the presence of bromide which is abundant in salt water. Environmental monitoring in Milford Haven has found that bromide concentrations range between 43-59 μg l-1 32. When chlorine (or hypochlorite) is added to seawater it oxidises the bromine ions yielding hypobromous acid. Although the best techniques for measurement and the exact identity of what is being measured have not been established, it is generally agreed that the reactions lead to the complete disappearance of all measurable chlorine and chlorine produced oxidants (CPO) (Rajagopal et. al., 2005). Therefore, the concern relating to the use of oxidants is due to the likely release of chlorination by-products (CBPs) in the effluent stream, including organohalogens, of largely cryptic identity, loading and impacts (Taylor, 2006). It is likely the harmful effects of chlorinated discharges are attributed to the reaction by-products. Hypochlorite / hypobromite can also react with ammonia and organic matter to form toxic compounds such as amines and organohalogens. For example among the chlorine by- products trihalomethanes have raised some concern as they are relatively long lived in the coastal marine environment (Rajamahan et. al., 2007). However, it is estimated that the half life of hypochlorite is less than 2 hours (Sorokin, 2007). We have considered these points within our assessment. The disinfectant properties of chlorinated seawater are expressed by a mixture of (mainly brominated) oxidizing compounds of which hypobromous acid (HOBr) is the most important. It has been known for some time that reproductive tissues, especially sperm, and immature stages of the organisms are sensitive to very low concentrations of organohalogens, such as bromoform (Davis & Middaugh, 1978). As such, it is not just the concentration of chlorine that should be considered. Jenner et. al. (1997) reported the bromoform concentration in the plume of a coastal power station was measurable (0.26μg l-1) at a distance of 1.5 – 15km from the outlet of thermal effluents, although concentration of residual oxidants were below 0.03μg l-1 in the field. These oxidising compounds are of necessity acutely toxic, but are reactive, unstable and short lived, so present little threat to the ecosystem of the receiving water. The non-oxidizing secondary products, CBPs, are relatively stable and have the potential to result in chronic toxicity to marine biota. Fortunately they have only a limited tendency to bio-accumulate and, outside the immediate vicinity of a cooling water discharge, are found at concentrations two to three orders of magnitude below their acute toxic levels. This indicates that although their potential for causing environmental impact exists, in practical terms it is very limited33. The Milford Haven waterway is the busiest cargo port in Wales, currently the fifth busiest in the UK. The presence of two oil refineries, two liquid natural gas (LNG) terminals, and the Port of Pembroke with its ro-ro Irish Ferry, general cargo, and MoD activity, all result in a considerable amount of shipping; almost 11,000 movements were recorded in 2006 (Pembrokeshire Marine Management Scheme, 2008). These activities are all potential contributors to hydrocarbons in the Haven. Therefore, the potential for chlorination of the hydrocarbons that may be present in the cooling water system, must be considered. There is also potential for the formation of other chlorination by-products such as halophenols and haloacetic acids, by substitution and addition reactions. These reactions will only occur where the precursors are brought together in sufficiently high relative concentrations, at an appropriate pH, for sufficient time and, importantly, in the absence of competing reaction pathways, such as those which lead to the formation of halomethanes. Such reactions are highly unlikely to occur within the Milford Haven waterway.

32 Part II, Chapter 7 – Ecological Effects of Operational Physical Marine Changes, pg 50. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 33 BEEMS Science Advisory Report Series (2010) No 009 (BEEMS Expert Panel) Chlorination by-products in power station cooling waters - 55 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The reactions that yield the organohalogens will be variable and cannot be accurately predicted (Taylor, 2006). Also the concentrations of hydrocarbons or any other precursors present within the estuary are unknown, therefore any predictions of organohalogen concentrations are theoretical, but based on actual data from other cooling water discharges. This covers a range of discharge environments and the worst case concentrations were used. (refer to Annex II for further detail). The EA has taken expert opinion ((Environmental Toxicity Advisory Service (ETAS)) on the potential impacts of organohalogens, based on the information available, and considered these risks in completing this assessment. It should be noted that for some chlorination by-products limited toxicity data are available. The ability of seawater to consume chlorine appears to have no limit (Wong & Davidson, 1977), indicating auto-decomposition rather than simple reduction by organic material. Chlorine's acute biocidal activity correlates with its potential to oxidise but since it reacts with any oxidisable material it follows that its biocidal potential will be short-lived in waters of high 'chlorine demand'. Measurement of combined chlorine – the fraction bound to compounds in an exchangeable form - does not include all chlorinated compounds since many, mainly non- oxidants, are undetectable by all or some of the analytical methods. This disappearance raises some issues, for example ‘the discharge regulations usually refer to 'total' or residual chlorine which, for seawater, is not merely a misnomer but ignores the existence and potential toxicity of the reaction products. Also the identity and hence toxicity of some of these products will depend upon the chemical species (including pollutants) that were present originally in the cooling water’ (Lewis et. al., 1994). The environmental side effects of chlorination generally concentrate on the acutely toxic oxidant species rather than the chronic toxic effects of the non-oxidants (Lewis et al., 1994). In order to consider the concerns of Lewis et al. in relation to all oxidant species, the applicant undertook further laboratory analysis of decay rates of TRO, discussed below. The revised TRO modelling reported in January 2011 (this model supersedes previous modelling) extends the analysis within the Environmental Permit application. Laboratory results for TRO decay in water from Milford Haven are judged alongside literature values to select a first-order decay rate. The selected decay rate (0.03/min) was applied to the results of the conservative tracer simulation reported in the Environmental Permit application. As a sensitivity test, a slower decay rate of (0.02/min) was also used. Analysis of the results show the decay is not first order but the period after exertion of the initial demand can be approximated by a first order decay. In explanation, the graph is sloped, steeper at first then starts to level out. If provision is made for the exertion of initial demand over the first minute or so, best fit first order decay coefficients are in the range 0.03- 0.035/min. It should be noted that the initial demand will occur within the power station, prior to discharge, where the dosed and undosed waters will combine. If the entirety of each experiment is fitted using first order decay, decay coefficients in the range 0.034-0.044/min are obtained. The work was carried out at laboratory temperature using Pembroke seawater gathered in June 201034. Pembroke laboratory studies have considered the likely temperature dependence of the coefficient. From a study of temperature decay relationship using Fawley power station water (near Southampton), a decay coefficient of 0.03/min would appear as an appropriate base case for modelling Pembroke TRO decay. This is a first order decay process, with no provision for rapid demand occurring through mixing, after the discharge has been made. Results of Davis & Coughlan (1983) suggest this would be a precautionary assumption. From the available data and consideration of the water temperatures occurring in the chlorination season, a coefficient of 0.02/min is a suitable precautionary choice for a sensitivity study38.

34 RWE, 2011. First order decay modelling of the TRO plume from Pembroke CCGT cooling water discharge, pg 13. ENV/445/2011. - 56 - Figure 5.1 Laboratory TRO decay curves using Pembroke seawater June 2010 (figure 2.6.1, report ENV/445/2011). The proposed emission value is 0.05mg/l.

5.1.3 Compliance with Environmental Quality Standard (EQS)

Defra and Welsh Government set an EQS of 10 μg l-1 95 percentile chlorine as Total Residual Oxidant under the Water Framework Directive (WFD)35 (refer to table 5.1). The EQS is a safe chemical standard, conservatively derived on a substance specific basis, to protect the most sensitive species. The current threshold of 10 μg l-1 95 percentile, is the required standard for the protection of marine life. Consideration of the potential impact has been carried out in accordance with the mixing zone guidance WQTAG083f36. RWE are proposing that only part of the cooling water stream would be chlorinated at any one time. The combination of non-chlorinated and chlorinated cooling water streams prior to discharge will result in a rapid reduction of oxidant concentrations. As a result RWE predict that the final discharge concentration will be no more than 50 μgl-1, i.e. 5 times the EQS. The resultant oxidant in the discharge will then rise to the surface with the thermal plume of the water. The buoyancy promotes spreading at the surface and reduces vertical mixing.

35 The River Basin Districts Typology, Standard and Groundwater threshold values (Water Framework Directive) (England and Wales) Directions 2010 36 N Babbedge, M Taylor 2005 Water Quality Technical Advisory Group on Water Quality WQTAG083f. European Marine Sites: toxic substances and associated mixing zones. - 57 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The mixing zone in the EA guidance WQTAG083f, is defined as the ‘area of water within which we are prepared to accept EQS exceedance’. It also states that ”the effects of all mixing zones across a site need to be assessed on a features /sub-features basis”, and that ”it is not possible to provide standard thresholds of the percentage or areas of features affected which constitute an adverse effect on integrity”. It also notes that ”the acceptability of the mixing zone must be determined through discussions between the Environment Agency and NE/CCW”. The mixing zone guidance WGTAG083f was a jointly agreed document with CCW and Natural England in 2005, but in correspondence from CCW (1st November 2010) they considered that ‘The proposal for mixing zones is incompatible with the Conservation Objectives, regardless of their scale relative to the relevant features or overall SAC size. We advise therefore that because the COs will not be met, a TRO mixing zone or a thermal mixing zone will result in adverse effect on site integrity’. Despite this opinion, we do consider that there are scenarios where mixing zones are compatible with COs. The following sections consider this point in more detail.

Table 5.1 Environmental standards for chlorine37

5.1.4 Extent of the mixing zone RWE state that the exceedance of the statutory limit is smaller in the current modelling than that of previous models, as a result in the change of modelled power station operation, despite the greater range of tides covered in the current model. The model run by RWE in 2011 has extended the above approach to include analysis of predictions for a full spring- neap cycle at the equinox. Refer to figure 5.2 for sea surface and sea bed exposure of EQS exceedance. At the point of discharge, the anticipated concentration (50 μg l-1) will be significantly lower than at the point of chlorination (500-1000 μg l-1) within the cooling water system inside the power station.

37 As in footnote 15 above. (a) Total available chlorine is the sum of the residuals of free available chlorine (FAC) and combined available chlorine (CAC). FAC is defined as that residual chlorine existing in water as chlorine, as chlorine, hypochlorous acid and hypochlorite ion. CAC is defined as that residual chlorine existing in water in chemical combination with ammonia (i.e. monochloramine, dichloramine or nitrogen trichloride) or organic nitrogen compounds. - 58 - The extent of the TRO mixing zone has been modelled for both base case (0.03/min) and the precautionary (0.02/min) choices of decay coefficient, the extents of which are demonstrated in figures 5.2 and 5.3 below. For each map, the terminology used refers to:-

- 59 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Figure 5.2 Sea surface (left map) and sea bed (right map) distribution of percentage of time that the 10µg l-1 95 percentile TRO, is exceeded, at a base case decay rate (0.03/min) (figures A.3.1 & A.3.2 RWE report ENV/451/2011)

At the sea surface The surface 10µg l-1 95 percentile exceedance extends seaward approximately 730m and landward approximately 280m. It extends up to approximately 750m offshore but does not approach closer than approximately 300m to the north shore. The surface extent of the 5 percentile exceedance (over the equinox spring neap cycle) contour is approximately 780m alongshore and 300m offshore. At the sea bed The 10µg l-1 95 percentile assessment standard is exceeded at the sea bed in a region extending approximately 150m in all directions.

Figure 5.3 Sea surface (left map) and sea bed (right map) distribution of percentage of time that the 10µg l-1 95 percentile TRO, is exceeded, at the precautionary decay rate (0.02/min) (figure A.3.3 & A.3.4 RWE report ENV/451/2011)

- 60 - At the sea surface The surface 10µg l-1 95 percentile exceedance extends seaward approximately 990m and has an exceedance for more than 5% of the neap spring cycle. It extends up to approximately 550m landward and 600m offshore. At the sea bed The sea bed 10µg l-1 95 percentile exceedance extends seaward approximately 200m, it extends up to approximately 250m landward and 650m offshore. The 10µg l-1 95 percentile assessment standard is exceeded for more than 5% of the neap-spring cycle, extending approximately 230m from the outfall.

Figures 5.2 and 5.3 provide an indication of the extent of the potential mixing zone. The duration of the dosing will occur for a maximum of 9 months of the year from April to December inclusive. This will be a condition of any permit granted. Table 5.2 shows the results for alongshore and offshore extents of the surface footprint (100 percentile) for the first order decay approach compared with the estimates previously reported.

Table 5.2 Indicative extents of surface footprint (Interior of zero percentile exceedance contour) of 10μg l-1 TRO concentration through equinox spring-neap (table 4.1, RWE ENV/451/2011)

First order decay rate Alongshore extent (m) Offshore-extent (m) 0.02/min Matlab contour 1500 660

0.03/min Matlab contour 1050 500

For the purposes of this assessment, RWE’s results at these points have been used to estimate the location of the EQS contour (10µg l-1 TRO 95 percentile). The contour is modelled as extending over about 4.72ha at the bed and 21ha at the surface38. As is to be expected, these values are significantly smaller than the maximum footprint (i.e. the 100th percentile) visible in the animations that accompanied the TRO report39. In using the above results in the context of annual percentiles, it should be noted that the proposed chlorination season is from April to December inclusive. Thus, since chlorination would not occur for at least 3 months of the year, exceedance of 6.67% of the time in the chlorination season would correspond to an annual 5% exceedance assuming the statistics of the equinox spring-neap were indicative of the chlorination season40.

38 Updated cumulative 95 percentile footprint figures in email dated 25th Feb 2011. 39EA Southern Region Marine Team. Report 10289. Final with update 24 April 2011. Pembroke Power Station – Cooling Water Discharge (thermal and TRO impacts). 40 RWE, 2011. First order decay modelling of the TRO plume from Pembroke CCGT cooling water discharge: second addendum on statistics of TRO concentrations, 7th Feb 2011, ENV/445/2011. - 61 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.1.5 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11 risk matrix: ƒ Coastal lagoons (Priority feature); ƒ Estuaries; ƒ Large shallow inlets and bays; ƒ Mudflats and sandflats not covered by seawater at low tide; ƒ Reefs; ƒ Sandbanks which are slightly covered by sea water all the time ; ƒ Submerged or partially submerged sea caves; ƒ Grey seal (Halichoerus grypus); ƒ Anadromous fish (Pembrokeshire Marine and Cleddau Rivers SAC); ƒ Otter (Lutra lutra) (Pembrokeshire Marine and Cleddau Rivers SAC); The potential risks from exposure of the above features to sodium hypochlorite biocide could include direct toxic effect on marine organisms. Where the effects are lethal, removal of individual species may result in the loss of key grazers or predators, and a dominance of pollution tolerant organisms. Sub-lethal effects however, may affect the healthy functioning of organisms such as its reproduction, physiology or genetics which may ultimately reduce the organism’s fitness for survival. Faunal communities within sediments, which primarily consist of species relying on larval dispersion for recruitment, are particularly recognised as being sensitive to toxic contamination. Planktonic organisms have limited powers of locomotion, at least horizontally, and consequently they are more or less passively drifted by the water currents. They include plants (phytoplankton), animals (zooplankton) and bacteria (bacterioplankton) (Boaden & Seed, 1985). Animals feeding on contaminated food sources are also directly at risk from substances that have the potential to biomagnify in the food chain. The primary uptake route for toxic substances is likely to be via the food. Consequently, the substances that pose the greatest hazard are those that have the potential to bioaccumulate, those that are toxic to invertebrates and fish and possibly those identified as having potential endocrine disrupting effects (Cole et. al., 1999). Each of the above potential hazards had been considered in section 5.1.5.1. Of the features listed above, CCW’s condition assessment indicates that the following habitats are unfavourable and declining: ƒ Estuaries; ƒ Mudflats and sandflats not covered by seawater at low tide; ƒ Large shallow inlets and bays. the following features are unfavourable, no change ƒ Reefs; ƒ Sandbanks which are slightly covered by sea water all the time; ƒ Lamprey.

- 62 - Appendix 3 ‘In-combination matrix provided by CCW 280610’ describes whether or not the ‘elements of favourable conservation status’ will be met for each feature. It notes for TRO, some requirements may be undermined because it is possible to identify the pathway by which Westfield Pill organisms would be affected as a consequence of increased temperature and TRO in the Haven. Also effects on plankton stages of lagoon species. It also notes that the ‘biocide in the cooling water discharge will impede biological processes.’ This is discussed in the next section.

5.1.5.1 Coastal lagoons (Priority feature) The coastal lagoon that could potentially be affected by the chlorination by-products of the biocide is Neyland Weir Pool, on the Westfield Pill. Coastal lagoons are categorised as such as they are protected from the full effects of coastal conditions by a barrier. The lagoon at Westfield Pill was established in the mid 1980s and is approximately 0.3 hectares. This lagoon is predominantly influenced by a high freshwater input and therefore has variable salinity, with saline intrusion restricted to spring high tides. Essentially however, it is an extremely sheltered environment. The Regulation 33 advice (2005) describes the lagoon as having limited habitat availability and recruitment. In addition the range of species present at the site’s lagoons has been enabled, rather than endangered, by the artificially impounded water bodies. The ranges of the lagoon species are, within the constraints of each species’ adaptation to physical factors and biological interaction, temporally and spatially variable. It is also worth noting that CCW have assessed the coastal lagoon habitat as favourable. The typical species particular to Neyland Weir Pool, which include the tentacled lagoon worm Alkmaria romijni and the amphipod Gammarus chevreuxi, are apparently in low numbers. The tentacled lagoon worm is a true brackish water species, usually not occurring at salinities above 18 parts per thousand (ppt), though it can tolerate higher salinities for short time periods. It is a surface deposit feeder (Nunes et. al., 2008), using the thin, sticky tentacles to collect food particles. It occurs in muddy sediment in sheltered lagoons and estuaries (Wesenberg-Lund, 1934; Ditlevsen, 1936). It is also not essentially confined to lagoons, but can also be found in sheltered parts of estuaries. The fact that it does not have a planktonic larval stage, is very small and has specific habitat requirements makes it unlikely that it has been able to disperse by its own means and hence it is presently considered cryptogenic. Changes in sediment characteristics, e.g. decrease in mud, increase in gravel or sand, or in other physical characteristics such as particle size or aeration, may affect its distribution (Pembrokeshire Local Biodiversity Action Plan). Therefore dredging within Neyland marina and agricultural run-off has potential for a significant effect on these species. A likely significant effect could occur, because it is possible to identify the pathway by which Westfield Pill organisms would be affected. However, given the location of the Neyland Weir Pool on the Westfield Pill at a distance of over 4km from the limit of the exceedance, shown in figure 5.4. Even though the plume will be larger at high spring tides when the tidal inundation of the lagoon occurs, the modelling shows that there will be significant decay of the biocide and associated by-products to such a level as to dismiss the probability of effect on the lagoon species. There is no possibility of there being an EQS exceedance within the lagoon, as shown in Figure 5.4.

- 63 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 5.4 The location of Neyland Weir Pool in relation to the approximate TRO exceedance at the seabed and surface.

5.1.5.2 Estuaries This section presents the available literature, which we reviewed for this appropriate assessment. The following paragraphs highlight potential concerns from different reports, that were then considered when reaching our conclusion. Estuary habitat is vulnerable to the effects of chlorination as it provides a spawning, nursery and feeding ground for many fish species, not to mention its importance as a passageway for migratory fish. Available toxicity data indicates that the early life stages are more susceptible to the toxicity of chlorine (Lewis et. al., 1994), and that these larval stages are likely to be entrained into the cooling water system where they will also be subjected to the effects of pressure changes, water treatment chemicals and thermal increase. As a consequence the major concern with respect to the typical species of the estuarine habitat are those which are entrained through the cooling water system. It is reported that oxidants are responsible for decreases in bacteria and phytoplankton biomass and production (Jenner et. al., 1998). It is also important to note that within the cooling water system these species will be exposed to concentrations considerably higher than RWE propose at the point of discharge, i.e. 50μg l-1. RWE anticipate that the dose at the point of chlorination will vary between (500-1000μg l-1)41.

41 Part II, Chapter 7 – Ecological Effects of Operational Physical Marine Changes pg 61. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. - 64 - The use of oxidants has long been understood to have an impact on entrained plankton (Taylor, 2006). Plankton species have limited or no motility and their occurrence and distribution within a sea area is thereby governed by external factors such as hydrodynamic regime, vertical mixing within the water column and so on. As plankton have no real mechanism for selective avoidance of unfavourable areas, they are susceptible to environmental changes, both natural and anthropogenic, including the direct influence of chlorinated discharges. It has also been observed that the early developmental stages of species are usually more sensitive to toxicity than adult ones, especially the larval stages41. The phytoplankton is especially important in marine food chains, as these organisms are the primary producers. Sorokin et. al. (2007) looked at available data on the effects of chlorine on phytoplankton. In a semi-field experiment using tanks under flow-through conditions, cell densities of phytoplankton were reduced by up to 50 per cent at exposure concentrations of 1–10 μg l-1 total residual chlorine (TRC) after a 21-day test. This data relates to intermittent exposures. Many small benthic organisms may be temporarily whirled up off the bottom by currents and turbulence, therefore the distinction even between planktonic and benthic organisms is thus less clear cut than might be presupposed. (Boaden & Seed, 1985). Chlorination at the intake screen will specifically target molluscs, barnacles and sponges for example: however, there will of course be an effect on the non target organisms. It has been observed that at concentrations of 100-250μg l-1 TRO, 25% of zooplankton entrained through power station cooling systems, were dead one hour after passing through the plant (Lewis et. al., 1994). More recently Vinitha et. al. (2010) observed that there was a significant reduction in ‘chlorophyll a’ as the water was passed from the intake point to the outfall, with a partial restoration of ‘chlorophyll a’ values as the discharge water mixes with the ambient sea. Their laboratory experiments demonstrated that growth rate, ‘chlorophyll a’ and primary productivity of chlorine-treated diatoms decreased, depending on dosage. However, there were species-specific differences in tolerance levels and recovery pattern among the diatoms tested. Also Brook and Barker (1972) showed that the effect of chlorination through a power plant depresses rates of photosynthesis and respiration to a much greater extent than the effect of heating. All the treatments of chlorination (0.13 ppm to 0.5 ppm) observed by Chio et. al. (2002) caused drastic inhibition of bacterial production and significant reduction of heterotrophic nanoflagellates and bacterial abundances, indicating some lethal effects on bacteria and heterotrophic nanoflagellates. Chlorine acts on the target organisms at organ, cellular and subcellular levels, and kills the organism depending on the dose and contact time (Rajagopal et. al., 2003). In the case of mussels, they are capable of protecting themselves from the deleterious effects of chlorine by shutting their shells. They have the ability to sustain themselves on anaerobic metabolism for a considerable length of time, often for several days (Rajagopal, 1997 in Rajagopal et. al., 2003). Early fish stages such as fry are reported to be the most sensitive to exposure to sodium hypochlorite (Sorokin et. al., 2007). Aquatic organisms also tend to be more sensitive to chlorine at higher temperatures, making them more vulnerable within the plume of the cooling water discharge. Hypochlorous acid reacts by chlorination of the nitrogen containing compounds in organisms such as amino acids. Consequently, biological processes such as enzyme function become impaired, resulting in negative effects and possibly death. In fish, chlorine damages the gills, resulting in increased mucous production and impaired respiratory exchange at the gill surface. Oxidation of haemoglobin may also occur resulting in reduced oxygen transport within the organism (in Sorokin et. al., 2007). However, in the this report the effect on the sediment dwelling organisms was not considered due to the rapid reaction of the chlorine with organic matter.

- 65 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Micro-organisms are numerically abundant in coastal waters and carry out many ecologically important roles in coastal ecosystems. Changes in microbial activities caused by changes in environmental conditions will thus confer significant impacts on functions of coastal ecosystems (Choi, et. al., 2002). Each of the above points have been considered during this assessment and expert advice taken on the technical detail. To avoid damaging scenarios such as that indicated in the above references, careful consideration of the sodium hypochlorite dosing has been undertaken by the applicant. This has focused on keeping the sodium hypochlorite dosing to the minimum concentration required and for the minimum period, to still allow operational functionality.

Bioaccumulation in typical species:

Taylor (2006) looked at the long-term exposure of sea bass to chlorination by-products (CBPs) and reported that analyses of muscle tissue revealed no bioconcentration of bromoform in fish exposed to chlorination (although some was present in the liver) and that the range of results indicated that long-term exposure to CBPs produced by low-level chlorination did not impose any apparent ecotoxicological stress on the sea bass concerned. Potential effects on the interest features of European marine sites include toxicity of chloroform upon invertebrates (in particular molluscs) at concentrations above 12μg l-1. Also based on available bioaccumulation studies and estimated bioconcentration factors, bromoform appears to have a low potential for the following reasons. Direct bioaccumulation from the water column is only likely to be a risk if the Log Kow42 is greater that 3. To assess the risks of direct uptake Predicted No Effect Concentrations (PNECs) have been derived from available toxicity data. It should be noted that for some of the CBPs the data are limited. PNECs provide a concentration that can be used to assess the risk of effects where there are no existing Environmental Quality Standards (EQS). Their derivation is more formulaic than an EQS, requiring less expert judgement and the resulting limit is much more precautionary41. Compliance with the Predicted No Effect Concentration (PNEC) should be protective against any adverse effects due to direct bioaccumulation from the water column. The predicted, worst-case environmental concentration, based on the data provided in Taylor (2006) is higher than the PNEC for three of the chlorinated by-products (CBPs) that may be present in the effluent and have a Log Kow greater than 3. The PNECs for each of these chemicals (2,4,6 tribromophenol, 2-chlorotoluene, and 1,2,3 tribromobenzene) are derived from sub-lethal, No Observed Effect Concentrations (NOECs). An additional safety factor of 500 or more has then been applied to the NOEC, depending on the quality of the data available. The PNECs are therefore highly precautionary. The predicted environmental concentrations are at least 100 times lower than concentrations where toxic effects have been observed. Neither 2-chlorotoluene nor 1,2,3 tribromobenzene are likely to be persistent in the receiving water. 2,4,6 tribromophenol is more persistent and is likely to bind to sediment but can be degraded anaerobically in the sediment. It should be noted that the concentrations in the estuary of hydrocarbons, or any other chemicals which might react with TRO, are unknown, therefore any predictions of organohalogen concentrations are theoretical but based on actual data from other cooling water discharges. This covers a range of discharge environments and the worst case concentrations were used.

42 LogKow or octanol-water partition coefficient is the ratio of the concentration of a chemical in octanol and in water at equilibrium and at a specified temperature. - 66 - It is possible that some temperature tolerant species like eels and bass will not avoid the thermal plume and in fact prefer this area. In these cases there is a potential for an increased exposure to area of higher levels of TROs. Due to the information discussed above, we have ascertained that any bioaccumulation will be neglible. Scale:

Environment Agency guidance (WQTAG083f) requires that the spatial extent of the mixing zones (i.e. the calculated exceedance of EQS) should be taken as the primary indicator of adverse effect. These are shown in table 5.3.

Table 5.3 Area of the estuary feature within TRO footprint43

Area within 10μg l-1 95 percentile TRO footprint Interest Area From Sea surface (decay 0.02) Sea surface (decay 0.03) feature (ha) Ha % Ha % Estuary 5472.5 CCW 37.41 0.68 20.85 0.38

Area Sea bed (decay 0.02) Sea bed (decay 0.03) (ha) From Ha % Ha % Estuary 5472.5 CCW 9.08 0.17 4.72 0.09

Volume:

CCW were concerned that water pumped through the power station would be sterilised before it was returned to the estuary. RWE provided some estimates of the tidal volume of Milford Haven. Their own model showed the maximum on a spring tide to be 400 x106 m3, whilst Williams and Jolly (1975) calculated 297 x106m3 for average tide, Hobbs and Morgan (1992) calculated 300 x106 m3 for spring tide. The latter is an average tidal flux of 15000 m3/sec compared to a cooling water flow of 40 m3/sec. So the cooling water discharge is approximately 0.26% of the average tidal flux. Therefore the plant exposes 0.26% of the water which leaves the estuary each tide, although some may be returned on the incoming tide.

5.1.5.3 Large shallow inlets and bays

Subtidal, intertidal and pelagic elements of the shallow inlets and bays feature will be subjected to levels over the EQS of 10µg l-1 95 percentile. The scale of the exceedance is detailed in table 5.4. The ria part of this feature is wholly encompassed in the estuaries habitat, however there is also some overlap with mudflats and sandflats. As such the discussion for this habitat is covered in section 5.1.5.2. Scale: Environment Agency guidance (WQTAG083f) requires that the spatial extent of the mixing zones (i.e. the calculated exceedance of EQS) should be taken as the primary indicator of adverse effect. These are shown in table 5.4.

43 EA Southern Region Marine Team. Report 10289. Final with update 24 April 2011. Pembroke Power Station – Cooling Water Discharge (thermal and TRO impacts). - 67 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Table 5.4 Area of large shallow inlets and bays feature within TRO footprint

Area within 10μg l-1 95 percentile TRO footprint Sea surface (decay Sea surface (decay 0.03) Area 0.02) Interest feature (ha) From Ha % Ha % Large shallow 22091.1 CCW 37.41 0.17 20.85 0.09 inlets and bays Area Sea bed (decay 0.02) Sea bed (decay 0.03) (ha) From Ha % Ha % Large shallow 22091.1 CCW 9.08 0.04 4.72 0.02 inlets and bays

5.1.5.4 Mudflats and sandflats not covered by seawater at low tide

Benthic species, particularly those that are sedentary, are more susceptible to the effects of toxic contamination in the marine environment by the discharge, compared to those species that are mobile, as they have limited ability to avoid the flow. Some mobile species would be expected to display avoidance behaviour or depressed activity may occur. There is limited information on the effect of chlorination by-products on benthic organisms. Studies have looked predominantly at the combined impacts of cooling water effects for example temperature increase and pressure changes, along with chlorination. Also any effects are likely to be more pronounced on the pelagic rather than benthic fauna owing to the buoyant nature of the cooling water plume. In Sorokin et.al. (2007) the effect on the sediment dwelling organisms was not considered, due to the rapid reaction of the chlorine with organic matter. Deleterious (sublethal) effects on sensitive species have been noted at concentrations as low as 10μg l-1 (Abarnou & Miossec, 1992). Figure 5.5 below gives an indication of the biotopes present in the vicinity of the proposed discharge. The sensitivity of these biotopes to TRO is assessed below.

- 68 - Figure 5.5: Biotopes in the area of the proposed power station44

MarLIN information was used by RWE in conjunction with LC and EC information to assess the influence of TRO and relevant chlorination by-products for a great variety of relevant receptors or proxies in the application. Although originally considered suitable, the external peer review found that the MarLIN assessment used by RWE that assesses the effects of synthetic compounds, was inappropriate, because the synthetic compounds were not specific to chlorine. Therefore this assessment is made using best available information on the sensitivity of the biotopes to the biocide and associated by-products. It must be noted that the time for recovery is indicated to be 3 months from January to March. Therefore full recovery of affected areas is only anticipated to occur on decommissioning. However this three month period will allow colonisation of less sensitive species into the vicinity of the cooling water discharge.

44 for full details refer to: RWE Combined Environmental Statement 2010, Appendix 4.5a, figure no. JER3566-010iii - 69 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Our literature search found one example for consideration in this assessment. For Atlantic Oyster (Crassostrea virginica) larvae the 48-hour EC50 was 26μg l-1 and for adult Acartia tonsa the lowest 48-hour LC50 was 29μg l-1. Although CCW have informed us that

Atlantic Oyster is not found within the Haven (pers. comms. October 2011), but instead European Oyster (Ostrea edulis) is found within the Haven, effects on oyster species are still a consideration. However, as the cooling water discharge is approximately 0.26% of the average tidal flux and the oyster larvae will be distributed evenly around the whole of the SAC by the tidal currents, it is ascertained that even though deleterious effects will occur to some Atlantic Oyster larvae, this will not affect the adult Oysters and as the cooling water discharge is approximately 0.26% of the average tidal flux, the quantity of larvae affected would be negligible in comparison to the volume of the rest of Pembrokeshire Haven estuary. Another literature search found that at Wylfa power station an apparent bleaching of epilithic algal populations in the immediate vicinity of the outfall was also noted, and considered to be a likely consequence of residual oxidant over that of temperature effects (Taylor, 2006). However in this scenario, other chemicals were being emitted which also had deleterious effects on the epilithic larvae. Scale: Environment Agency guidance (WQTAG083f) requires that the spatial extent of the mixing zones (i.e. the calculated exceedance of EQS) should be taken as the primary indicator of adverse effect. These are shown in table 5.5.

Table 5.5 Area of intertidal mudflat and sandflat feature within TRO footprint45

Area within 10μg l-1 95 percentile TRO footprint Sea surface (decay Sea surface (decay Interest 0.02) 0.03) feature Area (ha) From Ha % Ha % Mudflats & 1778.6 CCW 33.08 1.9 17.59 0.99 sandflats Sea bed (decay 0.02) Sea bed (decay 0.03) Area (ha) From Ha % Ha % Mudflats & 1778.6 CCW 6.33 0.36 2.49 0.14 sandflats

5.1.5.5 Reefs

The new modelling submitted by RWE shows that there is no reef habitat in the plume of the 10µg l-1 95 percentile TRO exceedance at the base case rate (0.03/min). However, a very small percentage of reef is beneath the surface cumulative footprint at the precautionary rate (0.02/min) but the footprint at the sea bed does not overlap this reef ( figure 5.6).

45 See footnote 46. - 70 - Figure 5.6. The location of the indicative reef feature in relation to the 10µg l-1 95 percentile TRO exceedance 0.02/min decay rate.

The reefs have a rich species diversity largely because of the structure of the rock surface (it can be pitted, and contain cracks and crevices for animals to live in). There are also mobile species such as lobsters (Homarus gammarus), spiny starfish (Marthasterias glacialis), urchins (Echinus esculentus) as well as territorial wrasse associated with the reef habitat. These mobile species will be able to avoid any adverse water conditions. Scale It should be stressed that the predicted area of TRO at the bed, where the reefs are located, will be zero, or very close to zero (0.0006%).

Table 5.6 Area of reef feature within TRO footprint

Area within 10μg l-1 TRO footprint Sea surface (decay 0.02) Sea surface (decay 0.03) Interest feature Area (ha) From Ha % Ha % Reefs 41006.6 CCW 0.24 0.0006 0 0

Sea bed (decay 0.02) Sea bed (decay 0.03) Area (ha) From Ha % Ha % Reefs 41006.6 CCW 0 0 0 0

- 71 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.1.5.6 Sandbanks

The potential impact on this feature relates to possible effects on mobile typical species. Typical species include plankton in the water column, fish such as bass and sand eels. As this habitat feature consists of soft sediment types that are permanently covered by shallow sea water, the diversity and type of community varies according to sediment type, geographical location, exposure of the coast and the depth, turbidity and salinity of the surrounding water.

5.1.5.7 Sea caves

Sea cave habitat is defined as caves situated under the sea or open to it, at least at high tide, including partially submerged sea caves. Their bottoms and sides harbour many communities of marine invertebrates and algae46. The potential impact on this feature is with respect to possible effects on mobile typical species, including planktonic stages, that could be impacted in the area of the plume. Sea caves make a significant contribution to the diversity of the reefs feature and are an essential part of the grey seal habitat. Sea caves typically support species that are “out of place” because caves provide areas which are physically different (e.g. darker, more sheltered) than immediately outside the cave (e.g. sponges typical of deep water in intertidal caves; mud dwelling anemones in sediments on the floor of caves in exposed rocky areas). Cave species differ according to the rock type of the cave. They often need to be very tolerant of scour and of extreme wave surge47.

5.1.5.8 Grey seal

Grey seals are known to inhabit the vicinity of the cooling water discharge. However, the seal pupping sites are located outside the Milford Haven waterway. Intertidal mudflats are also an important habitat for seals, hauling out and resting at other times of the year. Following several decades of irregular but substantial population increase, the population size (measured as pup production) slowed or possibly stabilised in the late 1990s – early 2000s (CCW, 2005). Grey seals can be exposed to toxic contamination through many routes, including uptake through the skin and ingestion of water and food. However, it is believed seals only spend part of their time in the estuary and tend to fish offshore for species such as cod, sand eels and shellfish. Secondary poisoning through the food chain is not considered to be a threat due to the high water solubility of chlorine and its rapid degradation in seawater (Sorokin et al., 2007). Taylor (2006) concluded that although some bromoform bioaccumulation was noted during annual chlorination seasons this accumulation rapidly dissipated thereafter. No impacts on growth and no damage to liver tissues were observed. Based on the available data the risk of secondary poisoning of top predators is assessed as low. Further information is provided in Annex II of this report.

46 EU Interpretation Manual ibid 47 www.pembrokeshiremarinesac.org.uk - 72 - 5.1.5.9 Anadromous fish

Water column contaminants are a potential threat to the physiological health of designated fish species. The migrations of anadromous species such as the river lamprey are particularly affected by pollution barriers because these may prevent fish moving from one life history habitat to another and therefore disrupt the life cycle. One polluting discharge between these two habitats can have a major effect on lamprey populations in a river (Maitland, 2003). It has been documented that early stages of fish are particularly sensitive to chlorine (Lewis et. al., 1994). These references have been considered by the EA whilst reaching a conclusion. River lamprey breed during the spring (March – April), whereas mature sea lamprey adults enter the estuaries from April onwards, and migrate into the rivers where their migration can be constrained by obstacles, either natural, such as waterfalls, or manmade, such as dams, weirs or pollution barriers. The upstream migration from the estuary appears to be triggered by temperature (Maitland, 2003). After hatching, lamprey juveniles remain burrowed in silt bed for the duration of their juvenile life and emerge as metamorphosing transformers after 5-6 years. They then commence their migration back to the sea, an event that usually occurs at night during June, where they will spend their adult life until they return to the rivers to spawn and die. The more sensitive egg and larvae stages will therefore not be exposed to the biocide in the discharge. Some fish may display avoidance behaviour or depressed activity at 5 μg l-1 total available chlorine (TAC) expressed as a maximum allowable concentration (EA, 2007). However, the tendency for avoidance has not been documented for lamprey. If it were to occur it may potentially affect migration or at least slow the progress of adult fish ascending the estuary. Note – The EQS for TAC is for freshwater, with TRO being the appropriate EQS for saline waters. Therefore, the latter has been used in our assessment. Typically, the return migration of adult lamprey involves active swimming on a constant bearing while vertically casting through the water column to locate odour discontinuities that indicate the presence of a pheromone-activated stream discharge (Vrieze & Sorensen, 2001; Sorensen et. al., 2003). The TRO modelling, as checked by the EA, found that in the maximum footprint scenario on spring tides, 15% of the cross-sectional area of the channel is subject to an increased concentration mixing zone and this is entirely within the thermal plume. The discharge plume is buoyant and as lamprey have no swim bladder, or any type of hydrostatic organ to sustain neutral buoyancy (Hardisty & Potter, 1971), they will travel deeper in the water column, therefore avoiding the plume. Twaite and allis shad are not known to spawn in the Cleddau catchments, but they use the marine waters outside the estuary to migrate to the Tywi catchment where they are known to spawn. As the Milford Haven waterway is not a spawning migration route for shad, no threat to these species can occur from the biocide in the cooling water discharge. However, if some shad were to pass into the estuary it is very unlikely they would be affected, because they will swim along the cross sectional area of the estuary that is below the buoyant plume – as shown in figure 5.11 in the next section.

5.1.5.10 Otter

Otters are known to feed in the vicinity of the outfall. However, they are mobile and not restricted to one habitat type, they also display opportunistic feeding behaviour. They will be able to detect adverse conditions within the pelagic zone and avoid areas of stress.

- 73 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Secondary poisoning through the food chain is not considered to be a threat. Due to the high water solubility of chlorine and its rapid degradation in the environment, bioaccumulation of chlorine species is not considered of importance in the environment (European Commission, 2004). Taylor (2006) observed that although some bromoform bioaccumulation was noted in sea bass during annual chlorination seasons this accumulation rapidly dissipated thereafter. No impacts on growth were observed and no damage to liver tissues was observed. Based on available data the risk of secondary poisoning of top predators is assessed as low, further information is provided in Annex II of this report.

5.1.6 Summary of the potential effects of toxic contamination

Evidence

The applicant proposes to use a combination of plant design and mechanical measures to reduce biofouling and ultimately the use of sodium hypochlorite. Dosing of hypochlorite is proposed to be limited to the mussel growth season from April to December inclusive, with the flow alternating between different sections of the power station, so that dosed and undosed waters will combine within the power station, allowing the final concentration at the point where it enters the estuary, to be lower. We have ascertained that the applicant is employing BAT and we agree with the evidence supplied by the applicant. The applicant was aware of the Defra and Welsh Government Environmental Quality Standard (EQS) of 10μg l-1 chlorine as Total Residual Oxidant (TRO) as a 95 percentile, so modelling work was undertaken to identify the actual discharge concentration at the discharge point and the extent of the mixing zone, to identify any potential effects. Due to the combination of non-chlorinated and chlorinated water streams prior to discharge, the predicted final discharge concentration will be <=50μg l-1. As such the modeling considered the maximum concentration of TRO (50μg l-1) at the discharge point using an extensive range of tide states, to create a precautionary model. Expert technical judgement

We have checked the quality of any data used and the validity of assumptions. Our literature searches highlighted some confusion within the scientific community (Taylor, 2006 & Lewis et al., 1994) as to the chlorine reactions, however we took expert opinion from our Environmental Toxicity Advisory Service (ETAS) and considered data from other similar power stations to reach a considered opinion on any risks to the environment. The applicant considered the fate of chlorine in salt water, due to the presence of bromine ions. Using environmental monitoring of bromine concentrations and the latest scientific understanding of oxidation products, we have ascertained that whilst they are toxic, they are reactive, unstable and short-lived. Due to the dosing point being within the power station itself, we consider them to present a negligible threat to the environment. The applicant considered non-oxidising secondary products - chlorination by-products (CBPs) and found that they have a limited tendency to bio-accumulate and are rapidly diluted within the power station to levels which are considered not toxic. The BEEMS (2010) report further confirms that their potential for causing environmental impact is very limited.

- 74 - Predicted physical /chemical/biological effects on the ecology

Expert technical judgement from within and outside the Environment Agency has been used to consider the types of potential hazards posed by this application. We have ascertained that there would be no impact on life forms or features using local knowledge and scientific peer review. The habitat would not be significantly affected (i.e. its extent, structure and ecological functioning would not compromise conservation status, because the potential effect will affect an area too small an area to make any material difference to its character). Our reasoning includes the ability of species to adapt behaviour, re-establish elsewhere or otherwise adapt to the changed conditions in the proximity of the potential hazard. Sensitivity/resilience to that hazard.

We have ascertained that:- ƒ The biocidal potential is short lived in Milford Haven waters, supported by the research within the BEEMS Science Advisory Report Series (2010) No 009; ƒ Decay rate modelling for TRO indicates a rapid reduction in concentration within the first few minutes of exposure; ƒ Volumetric analysis has identified that the discharge will only contribute 0.26% of the average tidal flux volume; ƒ The bioaccumulation of TRO and CBPs has been found to be below levels that would result in physiological damage, immune or reproductive suppression; ƒ The precautionary mixing zone area will only include up to 1.9% of the mudflats and sandflats feature.

Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each sub-element of the COs, using the information supplied by CCW in Appendix 3 ‘In-combination matrix provided by CCW 280610’. They have not been repeated in this conclusion to save space within this document. Unfortunately, the way that CCW have phrased some of these elements means that no project with any emission other than a remedial project could be authorised without failing to meet the individual elements of favourable conservation status. As a result we have found that the COs are not compromised but as some of the COs sub elements are not feasible or achievable - more aspirational, then some of the sub elements of the COs are not met.

Mitigation

Conditions will be placed onto any proposed environmental permit that will limit of the use of sodium hypochlorite to that considered within this appropriate assessment. Further details can be found within the decision document.

Remaining doubt

Initially there was doubt about the decay rate of TRO. The applicant undertook additional scientific research, to identify the decay rate within the Haven. We have ascertained that this is the best available information.

- 75 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain with regard to the ecological response, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that the remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

5.1.6.1 Individual feature conclusions Coastal lagoons

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that: “It is possible to identify the pathway by which Westfield Pill organisms would be affected as a consequence of increased temperature and TRO in the Haven. Also effects on planktonic stages of lagoon species.” We ascertained that although we could identify a hydrological pathway, 4000m to the nearest coastal lagoon at Neyland Weir Pool, the significant decay of the biocide and any associated by-products would make any effects on this site negligible. Equally the volume of water being exposed to TRO represents only 0.26% of the tidal cycle and so we would be confident that the effect on planktonic stages of lagoon species would be negligible. CCW’s condition assessment indicates that this feature is in favourable maintained conservation status (2006). We do not consider that any effects will occur to reduce this conservation status. Estuaries Large shallow inlets and bays Mudflats and sandflats not covered by seawater at low tide.

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘Biocide in the cooling water discharge will impede biological processes’. Our literature review highlighted a number of possible effects from the use of TRO on the estuaries feature. It should be noted that the TRO scenarios referred to (for example Taylor, 2006 and Brook and Barker, 1972) used a variety of TRO concentrations, different from this proposal. We also considered that the biocidal potential is short lived in water of high ‘chlorine demand’, such as that found at Milford Haven, and decay rate modelling indicated a rapid reduction in concentration from the first few minutes of exposure. The scale of the mixing zone, which would only occur between April to December inclusive, has been assessed to vary between:- ƒ Estuaries - 0.38-0.68% of the sea surface and 0.09-0.17% of the sea bed, ƒ Large shallow inlets and bays, (0.09-0.17%) of the sea surface and 0.02-0.04% of the seabed. ƒ Mudflats and sandflats - 0.99-1.9% of the sea surface and 0.14-0.36% of the sea bed. When this is considered together with the assessment that the volume of sea water being used as coolant, in comparison to the tidal cycle is a very small proportion (0.26%). Equally the dredged channel (not part of this EPR permit) at the outlet will mitigate effects on the bed at certain tidal states, as the flow will go along the channel to deeper water, thus only exposing a smaller area to the cooling water at low tide states.

- 76 - As described by CCW, typical species of mudflats and sandflat include those species typical of the areas impacted by the discharge, so would include for example estuary rag worm Hediste diversicolor and bivalve Macoma baltica. Typical species of estuaries and large shallow inlets and bays, are those typical of the areas impacted by the discharge, so would include for example plankton in the water column, fish in the water column, typical muddy benthos species, typical mixed sediment benthos species, typical intertidal species, typical reef species etc. CCW’s condition assessment indicates that these three features are in unfavourable: declining conservation status. We understand the main reasons for this, from information supplied by CCW, are principally due to nutrient emission and habitat loss due to dredging. The discharge of the TRO will not exacerbate these causes of unfavourable conservation status, nor undermine measures to return it to favourable conservation status. In principle, this is due to the nature of estuarine environments which are very resilient and adaptable, due to the wide variety of environmental factors that they experience. For example in the document Re-establishment of intertidal rocky surveillance – (N.Meiszkowska, February 2011) ‘The surveys found that despite an increase in non-native species, which is likely to have resulted from the high volume of international shipping and recreational vessel traffic, it ‘did not appear to have significantly altered ecosystem structure and function at these sites’. Considering that this is an area which has suffered from Sea Empress oil spill in 1996, this is an excellent demonstration of how robust the Pembrokeshire Haven ecosystem is.’ As such, even though the use of TRO will impact on a small proportion of planktonic/pelagic species and some mobile near-bottom species, it is considered that the scale of this impact, will be negligible, when considered as an ecosystem approach as outlined in the Marine Strategy Framework Directive (see page 17 of EC Guidance on the implementation of the EU nature legislation in estuaries and coastal zones). In our opinion the potential effects of the very localised influence of TRO on benthic communities and on planktonic life-stages of benthic fauna would not adversely affect the ecological functioning of the sites. The typical species found within the mixing zone are widely found within the rest of the protected site outside of the mixing zone, and there is no acute effect occurring which would adversely effect the site integrity of the protected features. Reefs

There is no overlap between the TRO mixing zone and the area of the seabed containing the reef feature, because the thermally buoyant plume does not extend this far along the seabed. The other potential effect is that of affecting planktonic forms of the typical species For the same reasons given above, it is considered that the effect on the pelagic typical species will be negligible, due to the volume of water being used, in comparison to the tide. CCW’s condition assessment indicates that this feature is in unfavourable : no change conservation status (2006). Due to the reasons mentioned, we do not consider that the discharge of TRO will exacerbate unfavourable conservation status, nor undermine measures to return it to favourable conservation status. Overall, it is considered that the concentration of the biocide by-products will not have any effect due to the distance they are distributed from the mixing zone. Sandbanks and Submerged sea caves

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ’Typical species include those species typical of the areas impacted by the discharge and sandbanks, so would include for example plankton in the water column, fish like bass and sand eels.’ For sea caves any effects on ‘mobile typical species of caves, including planktonic stages.’

- 77 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 There is no overlap between the TRO mixing zone and the area containing the sandbanks and sea cave feature, due to the considerable distance from the discharge point – see Figure 4.7 and 4.8. We have ascertained that although we could identify a hydrological pathway, >10km to the nearest sandbanks/ 3km to sea caves, the significant decay of the biocide and any associated by-products would make any effects on this site negligible. Equally, the volume of water being exposed to TRO represents only 0.26% of the tidal cycle and so we are confident that the effect on planktonic stage of sandbank typical species would be negligible. CCW’s condition assessment indicates that the sandbanks feature is in ‘unfavourable: no change’ and sea caves in ‘favourable’ conservation status. Due to the reasons mentioned, we do not consider that the discharge of TRO will exacerbate the unfavourable conservation status of sandbanks, nor undermine measures to return it to favourable conservation status. Grey seals & Otter

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘Prey availability will be affected by increase of temperature (8.7 degrees C increase at outfall) and TRO (the EQS of 10ug/l as a 95 percentile is exceeded for approx. 1km upstream and 0.5km downstream on the seabed and approximately 1.8km upstream and 1.7km downstream on the surface)’. We have considered that grey seal and otter are currently in favourable conservation status, and that the risk of bioaccumulation and reduction in prey is negligible. Any contaminants present will be below concentrations that are potentially harmful to seals and otters physiological health and reproductive capability. This is based on our findings on bioaccumulation, the latest literature searches and background marine monitoring. Combining this with their wide feeding area both within and outside the plume, we do not consider that the discharge of TRO will worsen the favourable conservation status of sandbanks, nor undermine measures to return it to favourable conservation status. In fact it is anticipated that due to the increased temperature, prey availability will increase, with certain species preferring this area of the Haven. Anadromous fish (allis and twaite shad, sea and river lamprey)

The TRO modelling, as checked by the EA, finds that in the maximum footprint scenario on spring tides, 15% of the cross-sectional area of the channel is subject to an increased concentration mixing zone and this is entirely within the thermal plume. The discharge plume is buoyant and as lamprey have no swim bladder, or any type of hydrostatic organ to sustain neutral buoyancy (Hardisty & Potter, 1971), they will travel deeper in the water column, therefore avoiding the plume. Twaite and allis shad are not known to spawn in the Cleddau catchments, but they do use the marine waters outside the estuary to migrate to the Tywi catchment where they are known to spawn. As the Milford Haven waterway is not a spawning migration route for shad, no threat to these species can occur from the biocide in the cooling water discharge. However, if some shad were to pass into the estuary it is very unlikely they would be affected, because they will swim along the cross sectional area of the estuary that is below the buoyant plume – as shown in figure 5.11 in the next section. CCW’s condition assessment indicates that the anadromous fish feature is in ‘unfavourable: no change’ conservation status. Due to the reasons mentioned, we do not consider that the discharge of TRO will exacerbate the unfavourable conservation status of sandbanks, nor undermine measures to return it to favourable conservation status.

5.1.8 Site integrity implications with respect to toxic contamination

- 78 - Overall the Environment Agency, after considering fully the conservation objectives for Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers SAC ascertains that there is no adverse effect alone on site integrity. This is summarised in table 5.8.

- 79 - Table 5.8: Conclusions on site integrity, assessing the impact of biocide toxic contamination in relation to the conservation objectives of special interest features and the site.

Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be 3) Is the 4) Will there be 5) Will there be a 6) Will the 7) Will there be which the SAC of annex 1 changes conservation status interruption or direct effect on the natural range of indirect effects on has habitats to the of the feature degradation population of the the species the populations of Been (or composite composition of currently of the physical, species for which within the site be species for designated features) the unfavourable? chemical the reduced / likely which the site be reduced, habitats for which or biological site was to be was sufficient to the site processes that designated reduced for the designated or affect the site was designated? support habitats or classified, foreseeable classified integrity? (e.g. and sufficient to affect future, sufficient due to loss or reduction in species for which the site integrity? to affect the site degradation species the site integrity? of their habitat structure, was designated (quantity/quality), abundance or or sufficient to affect diversity that classified, the site integrity? comprises the sufficient to affect habitat over time, the site integrity? sufficient to affect the site integrity?) Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reefs No No Yes No n/a n/a n/a Sandbanks No No Yes No n/a n/a n/a Sea caves No No No No n/a n/a n/a Grey seal n/a n/a No No No No No Anadromous fish n/a n/a Yes No No No No Otter n/a n/a No No No No No

- 80 - 5.2 Changes in thermal regime

This assessment follows the key steps shown below:

5.2.1 Description of thermal loading

Direct operational effects on the Milford Haven waterway will derive largely from the operation of the ‘once-through’ main cooling water system (MCWS) which will use sea water to cool the exhaust steam from the steam turbines. The MCWS will pass cooling water abstracted from Pennar Gut, east of the power station site, through the steam turbine condensers before discharging the warmed water directly to the Milford Haven waterway to the north, via a dredged discharge channel. The dredged channel is not part of this environmental permit. However, it is proposed that this will contain the discharge and prevent flow across the mudflats during low water on mid and high range tides. At most tidal states the outfall is submerged and the mixing of the effluent with the Milford Haven water begins at the outfall. Circulation will be achieved using the main cooling water pumps located adjacent to the cooling water intake. As the MCWS is a once-through system, there will be no associated evaporative losses. Figure 5.7 shows the relative distances between the cooling water in take and out fall. RWE have committed to designing the power station to be Combined Heat and Power (CHP) ready (see Section 4.2 of RWE Report ENV/423/2010). The draft permit includes a condition which would ensure periodic review of opportunities to implement CHP, which may reduce the thermal loading of the discharge.

- 81 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 5.7: Location of the Power Station and the position of the cooling water intake and outfall.

In order to assess the hazards and reach a conclusion as to whether adverse effect would occur, the Environment Agency has undertaken a literature review of scientific papers which provide information relevant to this environmental permit. Thermal discharges tend to be less dense than the receiving waters so are usually buoyant. Therefore, some heat will be lost to the atmosphere, similarly heat may also transfer to sediments in shallow waters. Continuous thermal discharges to estuaries can result in a net increase in temperature of the water column (Cole et. al., 1999). For clarity, the different temperature ranges used in this report are referred to in the environmental statement: ƒ 7.6°C is the through plant temperature rise with a 40 m3s-1 flow of cooling water, in the system operation characterisation of the EP application; ƒ 8.7°C is the temperature rise above natural ambient at the point of discharge that would occur for cooling water flow of 40 m3s-1, with a through plant rise of 7.6°C (EP characterisation) and for an intake temperature rise above natural ambient of 1.1°C; ƒ The maximum ambient temperature has been assessed as 21.7°C as a 100 percentile48.

48 Part II, Chapter 4 – Marine Baseline information, pg16. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. - 82 - Note: The results differ in detail from those previously presented in the stage 1 application, partly because of the differences in proposed power station operation and partly as a result of the wider range of tides considered within the present assessment. Any differences have been carefully added to this appropriate assessment, to ensure that our final conclusions accurately reflect the most up to date information from the applicant. The modelling using a wider range of tides has allowed us to ensure we have considered all possible scenarios.

Background temperature of the water at the intake

The dominant variation in natural water temperature in Milford Haven is seasonal, leading to a well-defined variation through the year with monthly means from a minimum of 5 to 8°C in February to a maximum of 15 to 18°C in August, based on 1990–2006 figures from Angle Bay49. The long term temperature effect of a thermal discharge was estimated based on analysis of the former power station temperature data within the Haven (Carr Jetty/Pembroke Dock) and outside the Haven (St Gowan light vessel) over the period 1971-87. It was assumed the temperature difference was caused by operation of the power station. A calculation, based on this premise, of the long term temperature rise, in the central Haven, from the proposed CCGT power station produced a range of +0.1°C to +1.5°C with a mean of 1.0°C in parts of the central Haven area. Up estuary, away from the discharge (Picton Point, Lawrenny) the highest temperatures are observed at spring tides when the heat-affected water is moved further up and down the Haven. Further information about water movement can be found in figures 6.1 to 6.7 within the in combination section of this report. Closer to the discharge point the opposite is true; higher surface temperatures are associated with neap tides when there is a reduced tidal transport of water along the Haven. It is not possible to define a single worst case tide as far as the temperature simulation is concerned as maximum predicted temperatures in the Haven occur under different tidal conditions at different locations. The potential direct effects of an increase in temperature from the cooling water discharge include lethal and sub-lethal responses from organisms; stimulation of productivity; and a reduction in dissolved oxygen concentrations (English Nature, 2003). The thermal plume will be influenced by environmental processes including: ƒ Tide; ƒ Wind speed and direction; ƒ Atmosphere conditions; ƒ Freshwater flows In addition water temperatures are influenced by sunshine, the temperature of the air, the shape of the channel, and the velocity and depth of the water. Temperature is also affected by discharges of effluents, abstractions and changes in land use. Vertical temperature differences are found in estuaries, and temperature variations are also associated with tides and seasons.

5.2.2 Climate change

Over the next century, surface temperatures of the sea are forecast to rise by 0.5-4°C (UKTAG, 2008). This will change baseline ambient temperature of the estuary. Langford et. al. (1998) predict that the inlet temperature could rise by 3-4 degrees within the lifetime of the proposed power station. This will have an effect on the biocide regime, as a longer dosing period may be needed. However, this assessment is based on a dosing period from April – December and the environmental permit assessment is restricted to the current application.

49 Part II, Chapter 4 – Marine Baseline information, pg16. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. - 83 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Sea temperatures around the UK have increased over the past 25 years by up to 1°C (Hawkins et. al., 2003). The MarClim project50 has shown that rocky intertidal invertebrates and macroalgae around the coastline of the UK have undergone some of the fastest responses to climate warming globally, with rates of expansion or contraction of geographic range limits over ten times faster than those recorded for terrestrial systems (Mieszkowska, 2006, Mieszkowska, 2011). It has also provided strong evidence that recent rapid climate change has resulted in changes in the abundance, population structure and biogeographic ranges of a number of intertidal indicator species, mirroring changes offshore. Experiments have shown that many of the changes in southern/lusitanian species have occurred as a result of increased reproductive output and juvenile survival in response to increased warming51. Changes in the Milford Haven estuary have already been reported, especially with respect to the bass nursery, since the conservation objectives were published. This is mostly as a result of a rise in background sea temperatures and if it continues to rise, it is likely to restrict the ability of cold- water species such as salmon, sea trout and smelt to occupy southern estuaries (Turnpenny et. al., 2010). However it is yet to be seen, how much of this is part of a natural cycle. Climate change has been taken into account by RWE in their review of seasonal natural variations in sea temperature for the period 1989 to 2007. They have analysed temperature data from several sites around the Haven and applied predicted climate change effects on sea temperature (Pembroke B CCGT Modelling Report: Long Term Temperature Time Series Analysis Appendix 6.3 All.4 2007). UKCP02 climate change scenarios were used. This indicated that year to year seasonal natural variation in sea temperature for this period dominates any long term trend inferred for sea temperature rise due to climate change, approximately 0.24C for this 17 year period. RWE further concluded that any long term warming trend due to climate change is likely to continue to be dominated by the natural variations for several decades to come. (For information the proposed operational lifetime of the power station is 25 to 30 years). Climate change is seen as being part of the prevailing environmental conditions as defined within section 1b of this appropriate assessment. Notwithstanding RWE's view, given the potential significance of climate change on ambient temperature in the medium and long term, there will be a requirement of the permit to reassess the impact of climate change at regular intervals throughout the operational lifetime of the power station. The permit specifies that RWE must review their hydrodynamic modelling in light of the best available climate change predictions every 6 years. The review will assess whether any changes to the operation of the power station are required as a result of likely impacts. The Agency may either require a permit variation to be submitted or alternatively vary the permit itself to ensure operational changes to prevent or reduce any significant impacts as a result of climate change are implemented.

5.2.3 Temperature thresholds

Habitats Directive guidance (WQ TAG160) states that where habitats and species are potentially at risk from changes to the thermal regime, it considers that a mean temperature change of more than 0.2°C in a significant area of the site should be considered as likely significant effect52. This is a precautionary way of screening discharges so that all discharges which could be significant are assessed in detail. This has been the basis for this assessment and is a screening assessment trigger for the following, more detailed analysis. There are currently no statutory thermal standards for estuaries. UKTAG states that for estuaries and coastal waters there is inadequate information to link ecology generally to the complex thermal structure created by thermal gradient. Regulatory controls should focus on the individual thermal discharges and ensure that the extent of the mixing zone allows the ecology to meet the objectives of the Water Framework Directive.

50 The MarClim project was a four year multi-partner funded project created to investigate the effects of climatic warming on marine biodiversity. 51 www.mba.ac.uk/marclim/ 52 Operational Instruction: 141_07 2008. Applying the Habitats Regulations to water quality permissions to discharge: reviewed and new applications. Environment Agency. - 84 - The ‘BEEMS Science Advisory Report Series (2010) No 008 (BEEMS Expert Panel) Thermal standards for cooling water from new build nuclear power stations’ report provides an overview of all significant issues pertaining to thermal discharges to Transitional and Coastal waters. In essence, the review confirms the fact that adverse effects of cooling water (CW) outfalls are restricted to an area close to the plume, that temperature rises up to 3°C appear to be tolerable and that resulting temperatures less than 27°C have no clear deleterious impact on species in the receiving waters. However, in the longer term, changes in the local community may result as species with differing tolerances of elevated temperature show differing survival, growth and patterns of reproduction from those expressed under ambient conditions. Populations that persist in the receiving area of a heated CW effluent will acclimate to those new local conditions and may adapt in response to them. Superimposed on these changes, however, are community changes caused by species distribution alterations as the result of climate change. WQTAG16053 identifies two elements against which thermal impacts should be assessed and sets thresholds for an estuarine SAC (refer to table 5.9).

Table 5.9 Temperature thresholds for assessing the impact of thermal discharges on SAC/SPA sites

Designation Deviation from ambient Maximum temperature SPA 2°C as a Maximum Allowable 28°C as a 98 percentile at the Concentration (MAC) at the edge edge of the mixing zone of the mixing zone SAC (any designated for 2°C as a MAC at the edge of the 21.5°C as a 98 percentile at estuary or embayment habitat mixing zone the edge of the mixing zone and/or salmonid species)

Analysis by the EA’s specialist marine team has demonstrated that, at the edge of the iso- surface, corresponding to the +2°C maximum allowable concentration (MAC) temperature rise resulting from the power station operation, the water temperature would be expected to exceed 21.5°C only 0.7% of the time. Therefore, the 98 percentile condition of the WQTAG160 21.5°C guidance would be satisfied everywhere on and outside the +2°C temperature rise iso-surface. The predicted thermal impact would only occur within a 21.5°C maximum temperature condition over limited areas within those areas already failing to comply with a +2°C maximum temperature rise condition. A recent review of thermal sensitivity of biota, carried out to supplement the UKTAG work of 2008, recommends +3°C (as a 98 percentile) as an assessment guideline for estuarine and marine waters classified under Water Framework Directive as Good or Moderate ecological status (BEEMS Science Advisory Report Series (2010) No 008). This is in line with long-held guidance from UNEP (1984). This guidance implies that no further regulatory consideration should be given to waters meeting this standard (provided that the maximum allowable temperature of 23°C is also met at the 98th percentile), and that effort should be confined to considering the significance of any effects within the +3°C contour. That said, the Environment Agency is required to undertake its assessment using the standards included in the current WQTAG guidance, which states that the extent of the mixing zone should be calculated on the basis that the increase of the receiving water is 2 degrees C or more as a maximum. It must be noted though that, in light of this latest study, this approach is considered to be precautionary.

53 WQTAG160 2005. Guidance on assessing the impact of thermal discharges on European Marine Sites. - 85 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.2.4 The extent of the mixing zone

The mixing zone will be the area in which the discharge causes the water temperature to increase by more than 2°C at any time. There will be areas within that zone subject to higher temperatures. Since the phase 1 PPC application, additional thermal modelling output was requested during 2009 from RWE npower. We requested that the analysis was based on the spring equinox spring – neap cycle to ensure that an adequate range of tidal conditions were covered. We also requested that the modelling was carried out to look at the effects of peak load operation, a flow rate of 40m3s-1 and cross-station temperature rise of +7.6°C54. This information, submitted as part of the 2010 Environmental Permit application, has been reviewed and accepted by the Environment Agency’s technical marine team55, with the caveat that sensitivity testing of just one coefficient was presented which showed predictions changing by around 0.2°C. There will always be error margins associated with any modelling of the precise location and precise shape of predicted temperature or TRO contours. The Pembroke CCGT aquatic modelling is a standard application of the widely used Delft-3d modelling system. Its original development was guided by Delft Hydraulics Laboratory experts with input from NRA and CCW. An extensive site specific, calibration and validation programme including a wide range of sensitivity studies was carried out. Its report includes a comparison of model results with field measurements of the Pembroke A (the now decommissioned power station) thermal plume resulting from a thermal discharge very similar to that of the proposed CCGT. The report also contains long-term current meter and tide gauge deployments. The long-term field predictions were validated by temperature observations over several of the years that Pembroke A power station operated. The modelling has also been audited by Metoc for RWE Npower and by ABPMer for the Environment Agency. We therefore have considerable confidence in the validity of the Pembroke thermal modelling. A mixing zone is acceptable if it can be demonstrated that it will not have an adverse effect on site integrity (WQTAG160). Temperatures may be as high as 7.6°C above intake temperatures, however, only water in the immediate vicinity of the outfall will be subject to this temperature rise.

At the sea bed

The +2°C MAC assessment standard is exceeded at the sea bed in a region extending approximately 1.5km seaward and 1.2km landward of the outfall and up to approximately 750m off shore. There is no exceedance of the +2°C at the sea bed within approximately 500m of the north shore of the Haven, refer to figure 5.8. The length of the Haven from the south to north shore in the vicinity of the proposed power station is approx 1.2km, also there is a deepwater channel off the north shore. So over 50% of the channel may be exposed to an exceedance of the temperature threshold, at some point. Thus, further consideration of the frequency of exposure has been undertaken. The modelling shows that the largest modelled thermal mixing zone occurs on spring tides and covers up to 3.5% of the inter-tidal bed near the outlet56 at that time. At other times the mixing zone is smaller. However, this value does not represent the cumulative exceedance (i.e. the sum of areas that are, at some time, within the mixing zone, however briefly).

54 In the previous permit application only mean spring and neaps tides were modelled and validated, a flow rate of 38m3s- 1 was used and a temperature rise between the cooling water intake and discharge of 8.1oC. This characterisation was based on design information of 2006. Part II, Chapter 6 - Operational Phase Physical Effects on the Haven, pg32. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 55 EA Southern Region Marine Team. Report 10286. 2010. Pembroke Power Station – review of estuarine modelling included in Environmental Permit Application (JP3638LK) February 2010. 56 Part II, Chapter 7- Ecological Effects of Operational Physical Marine Changes, pg 39. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. - 86 - The footprint of the temperature effect illustrated in Figures 5.8 (using the 0 percentile lines) where the threshold is exceeded at any time in the spring neap tidal cycle. It represents the scenario for the maximum extent of the plume under standard spring and neap tidal conditions (whereas, in reality for example, part of the footprint may occur on the ebb, another part on the flood and other parts only on the most extreme spring tides etc)36.

Figure 5.8: Percentile exceedance distribution of +2°C at sea bed (figure 106, EPR application).

Figure 5.9 shows the area of the sea bed with maximum, 98th percentile and mean temperature rises exceeding a range of temperature-rise thresholds. The results have been obtained through post-processing of the temperature results within Matlab, excluding temporarily ‘dry’ cells for the period they are ‘dry’, and taking the entire area of a cell as either meeting or not meeting the threshold (i.e. no spatial interpolation). There is a significant reduction in affected area from a maximum temperature threshold of +2°C to a maximum of +3°C and the area is almost exclusively intertidal. Only a small area, experiences a mean temperature rise of ≥+5°C. For example the area of exceedence of 5°C is 51.78 ha as a maximum, 42.30 Ha as a 98 percentile and almost zero as a mean57.

57 Refer to table 2.1.1 of report ENV/463/2011 - 87 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 5.9 Sea bed area exceeding temperature rise thresholds (fig 2.1.3 of ENV/463/2011)

At the sea surface

Using figure 107 of the RWE 2010 CES (see figure 5.10) it is possible to estimate the extent of the exceedance of the +2°C MAC at the sea surface, to be in a region of approximately 4km seaward and approximately 2km landward. The sea surface exceedance of the temperature threshold will extend 1.2km to the north shore of the estuary and will extend for approximately 1kmalong the shore of the outfall.

- 88 - Figure 5.10: Percentile exceedance distribution of +2°C at sea surface (figure 107, EPR application).

Cross section

The cross section modelling illustrates the surface and sea bed exceedance. Figure 5.11 shows an example series of cross-sectional plots of temperature rise for a time of maximum proportion exceedence at the outfall channel section. The results show that the majority of the cross sectional area, including all of the north side of the Haven, does not exceed the +2°C maximum allowable temperature rise at the edge of the mixing zone 58.

58 Part II, chapter 6 - Operational Phase Physical Effects on the Haven, pg 38. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010 - 89 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 5.11: Milford Haven cross section at and near outfall channel showing exceedance of +2oC at low water spring at spring equinox (figure 109, RWE CES 2010).

Table 5.10 compares the footprints where +2°C is reached at any time (0 percentile) to the areas exposed to values exceeding the thermal standard for 5% of time. The 5 percentile thermal footprints are shown in figures 5.8 and 5.10. The modelled extent of the area exceeding +2°C MAC is much larger than the 5 percentile area. The thermal footprint reduces by 61%, from 543.9 ha to 211.9 ha59.

Table 5.10 Duration of exposure to +2°C

5% of time >0% of time

+2°C Surface 211.9 hectares 543.9 hectares

+2°C Seabed 89.0 hectares 136.1 hectares

RWE have calculated that the volume of water in the Milford Haven waterway exceeding +2°C, will vary from a minimum of 0.1 x 106 to 1.6 x 106 m3 60. The thermal impact (+2°C increase), is estimated to be from 0.2 to 0.26% of the estuary volume, This model uses 15 day spring neap modelling. It also agrees with the volumetric findings in section 5.1.5.2.

59 EA Southern Region Marine Team. Report 10289. Final with update 24 April 2011. Pembroke Power Station – Cooling Water Discharge (thermal and TRO impacts). 60 Part II, chapter 6 - Operational Phase Physical Effects on the Haven, pg 38. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. - 90 - 5.2.5 Dissolved oxygen

Aquatic organisms must have sufficient levels of dissolved oxygen (DO) in the water. The amount of dissolved oxygen in an estuary’s water is the major factor that determines the type and abundance of organisms that can live there. Oxygen enters the water through two natural processes: diffusion from the atmosphere and photosynthesis by aquatic plants. The mixing of surface waters by wind and waves increases the rate at which oxygen from the air can be dissolved or absorbed into the water. DO levels are influenced by temperature and salinity. The solubility of oxygen, or its ability to dissolve in water, decreases as the water’s temperature and salinity increase. For example, the solubility at 10oC declines from 11.3 mg l-1 in fresh water to 9.1 mg -1 in sea water (WQTAG088e61). The presence of salinity and/or temperature stratification within bodies of water can also influence the distribution of oxygen vertically and horizontally in the water column (Nixon, 1990). DO levels in an estuary also vary seasonally, with the lowest levels occurring during the late summer months when temperatures are highest. Bacteria, fungi, and other decomposer organisms also reduce DO levels in estuaries because they consume oxygen while breaking down organic matter62. The potential risk to the estuary is that a temperature increase in the estuary due to the cooling water discharge, may decrease the saturation level of dissolved oxygen. Within the thermal plume where the rise in temperature will exceed the guideline standard this might result in greater changes in saturation concentrations, which may present a barrier to fish migration. Because of this risk, the applicant has examined this in more detail. UKTAG (2006) has reviewed and recommended a dissolved oxygen standard for marine waters and concluded that a 95 percentile of 5.7 mg l-1 would be protective of salmonid life cycles (referred to in table 5.11). It also suggests that in transitional and coastal waters, a dissolved oxygen level of 2mg/l stresses the majority of fish species.

Table 5.11: Dissolved oxygen standards for transitional and coastal water63

(Note: This table does not take into account, the reducing solubility of oxygen as salinity increases).

61 WQTAG088e. Wither, A. & Babbage, N. 2004 Dissolved Oxygen Limits for Estuaries: Determining likely significant effect. 62 Reference: national ocean service education, web address: http://oceanservice.noaa.gov/education/kits/estuaries 63 Table 21 in UKTAG, 2006. UK Technical Advisory Group on the Water Framework Directive (Phase 1) Final Report August 2006 (SR1-2006). - 91 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 CCW’s Regulation 33 advice (April 2005) suggests that information on dissolved oxygen is limited but indicates that the water column is largely fully saturated throughout bays and inlets. Oxygen availability within sediments is mostly likely to be typical for the sediment structure. All available data for dissolved oxygen in Milford Haven Estuary was retrieved from the EA archive (WIMS) for the period January 1998 to August 2006. The data suggests a small decrease in DO concentration over time from an annual average of 8.9mgl-1 in 1998 to 8.3 mgl-1 in 2006, see table 5.12 for minimum and maximum yearly DO levels. The threshold level as determined for triggering likely significant effect for dissolved oxygen (DO) in saltwater is 5.7 mg l-1 (95 percentile).

Table 5.12 Showing maximum and minimum DO levels in Milford Haven from EA data

Year Minimum Maximum 10/06 – 08/07 6.8 mgl-1 (in Aug) 10.25mgl-1 (in Oct) 2008 6.34mgl-1 (in Nov) 11.51mgl-1 (in Feb) 2009 6.3mgl-1 9.14mgl-1

The solubility of oxygen in seawater depends primarily on salinity and temperature, so raising the temperature will lower the oxygen solubility. However, solubility will only affect the actual DO level when the ambient level is at or close to saturation. DO saturation levels will, in any case, vary naturally with season and state of the tide. For example, for a water temperature of 16°C and salinity of 34 ppt, the saturation concentration of DO is 8.02 mgl-1, and a 1°C rise in temperature results in a fall in saturation concentration of less than 0.2 mgl-1 (USEPA, 1985). Within the thermal plume, greater rises in temperature occur and lead to greater changes in saturation concentration. An 8°C rise leads to a reduction in saturation concentration of 1.1 mgl-1 with corresponding potential change in DO concentration, depending on the balance of mixing, re-aeration and possible degassing occurring within the plume (Turnpenny et. al., 2010).

Dissolved Oxygen conclusion

Minimum readings for all sample points within Milford Haven were greater than 5mg l-1, so it was not necessary to calculate 95 percentile values. In the area of the plume, even allowing for a precautionary temperature rise of up to 8oC would not result in DO readings below 5mg l- 1. Therefore, it is ascertained that there is no adverse effect alone on site integrity from low dissolved oxygen concentrations.

5.2.6 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix: ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mudflats and sandflats ƒ Reefs ƒ Grey Seal ƒ Anadromous fish ƒ Otter

- 92 - In order to fully consider all relevant information for this appropriate assessment, the Environment Agency has undertaken a scientific literature review, with the following information being found:- Water temperature has an influence on aquatic species. The effects can be seen in their growth and development, how they tolerate and metabolise toxic substances, success in reproduction, in resistance to disease and, ultimately, whether they survive or die. Temperature can also have an indirect effect on aquatic species by causing changes to water chemistry, and by its effect on the solubility and metabolic consumption of oxygen (UKTAG, 2008). Long term temperature rise also increases the risk of the establishment of non-native species. In addition the thermal discharge may create a potential barrier to fish migration (UKTAG, 2008). All species will have a thermal lethal limit and there has been evidence that seaweed species such as Fucus and Ascophyllum spp. decline in abundance when thermal discharges have resulted in temperature increases of 5-7oC above ambient (Cole et al., 1999). Steinbeck et. al. (2005) studied the long-term change64 in intertidal communities from impacts associated with a thermal discharge and concluded that the evidence was unequivocal within the impact area of Diablo Cove, in America. Major changes had occurred in impact areas and given the timing and spatial pattern this had provided strong evidence for both acute and chronic effects of the thermal discharge operating. However, the American study was based upon different biota to Milford Haven. Overall, it was found that changes to the marine environment by the discharge of heated effluents may vary greatly as a function of the quantity of heat discharged and of the climatic, hydrological and biological features of the environment. CCW in their Regulation 33 advice (April 2005) indicated that all the features of the SAC are potentially susceptible to the effects of thermal effluent discharges. Of the sensitive features listed above, CCW’s condition assessment indicated that the following habitats are unfavourable and declining:- ƒ Estuaries ƒ Mudflats and sandflats not covered by the sea at low tide ƒ Large shallow inlets and bays the following are unfavourable, no change ƒ Reefs In addition lamprey have also been classified as unfavourable, no change.

5.2.6.1 Estuaries

Estuaries are highly variable, unstable and stressful environments (especially with regards to salinity) and it is perhaps not surprising that relatively few species have evolved the necessary adaptations required to live there. Species richness is therefore generally much lower than in adjacent marine and freshwater environments (Boaden & Seed, 1985). Nevertheless, estuarine habitats are used by a large number of fish and crustacean species for part of their life cycle and are particularly important nursery areas. The sensitivity of estuaries to temperature fluctuations is difficult to assess, however the stresses to biota are seen to be compounded by fluctuations in other environmental factors such as salinity and DO levels. The organisms that have become adapted to estuaries have great tolerance to rapid changes in temperature and salinity that are helpful in resisting external forces, although some adverse human inputs are exceeding the capacity of some estuaries to absorb them65.

64 The study started in 1976, with sampling occurring before the plant became operational. 65 www.libraryindex.com/pages/3268/Estuaries.html - 93 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Consideration must be given to the maximum temperature of the cooling water and its contents, that the estuary will be exposed to within the system. There is also a need to consider that due to the operation, the ambient temperature in the estuary will increase, therefore the natural fluctuations in temperature i.e. the winter minima and summer maxima will also increase and this may result in higher extremes of temperature in the estuary especially during summer months. Estuaries are more sensitive to summer heat build up as flushing rates are lower than on the open coast and also large intertidal areas absorb solar radiation. For this reason, the added heat will dissipate more slowly during the summer (Nour El-Din, 2004). The rate of temperature change is rapid as the cooling water passes through the heat exchangers. At most power stations the rise is between 8-15oC, occurring over a period of 2-3 minutes or less. This rate of temperature increase and rate of temperature fall will be faster than in a natural habitat (Langford, 1990). Nour El-Din (2004) reported that the impact of cooling water is more pronounced on the pelagic rather than the benthic fauna. This may be due to the flowing buoyant nature of the low density warm cooling water and the physiological nature of the benthic organisms rendering them more resistant. Other notable features of onshore discharges that cross the foreshore are the potential for scour, especially across mudflats, and for displacing any longshore-migrating fish or other biota into deeper water (sometimes known as the “travelator effect”) (Turnpenny, et. al., 2010). This is most likely to affect juvenile fish such as glass eels or flounder, which ascend estuaries along the margins using selective tidal stream transport (Colclough et. al., 2002). This effect could be compounded when the geography of the area is considered in more detail, for example the dredged deeper north shore which accommodates significant numbers of port traffic up and down the channel. Also the prevailing wind is south westerly, so the fish may tend to favour the more sheltered, shallower south shore. However, the Haven is an important nursery for both sprat and sand-smelt. Small numbers of juvenile herring, plaice and flounder are all found at sites throughout the Inner Haven, therefore demonstrating these species are not just restricted to shallower waters41. There was also concern that the warmer waters of the thermal plume may encourage bass to congregate in increased numbers. It was thought that this proliferation of bass may have an effect on other fish populations in the vicinity as they prey upon small fish and crustaceans. However, studies of bass over the last 30 years, have changed our understanding of their ecology. As the whole of the inner Haven acts as a significant nursery for bass66 it is not believed, based on our technical knowledge, that any significant effect will arise from increased predation. Whilst the temperature increase due to the cooling water discharge may not affect the physical habitat part of the biotope, it is likely to affect the biotic element, resulting in changes in species composition within the mixing zone. Langford (1998) suggests there is ample evidence of changes in life histories, behaviour and distribution of species of algae, invertebrates and fish within near field areas of thermal plumes. Consequently, the effect of the discharge in the long term is likely to lead to a changed and thermally adapted community, within the immediate vicinity of the discharge mixing zone, more typical of that found in otherwise more southerly warmer climates. However, this does not necessarily imply that the site, will fail its conservation objectives.

66 S. Colclough, Marine fish nursery function in the Inner haven, 2011. Annex I. - 94 - Some introduced invertebrates, including non-native oysters, may be able to reproduce and thrive in artificially heated regimes. Langford et. al. (1998), reported that non-native species are present in abundance in the Haven. Mieszkowska (2011) reported that the Milford Haven waterway has high numbers of non-native species in comparison to the UK wide MarClim database, including a notable increase in abundance of slipper limpet, Crepidula fornicate and Pacific oyster, Crassostrea gigas. This is likely to be a result of shellfish farms within the region and transference from the high volume of international shipping and recreational vessel traffic to and from the waterway. There is also evidence that the American oyster Crassostrea virginica is currently breeding in the Haven, at the low end of its thermal tolerance limit. It has been suggested that there is a low risk of recruitment in Milford Haven, although it is possible that local warming may occur at the head of the estuary (Syvret et al..2008). Wales is predicted to become a high risk region for the establishment and spread of Pacific oysters by 2040 based on a predicted warming of the sea by 0.40C per decade (Minchin, D. & Gollasch, S. , 2008). However, it is uncertain how this generalisation would apply to Milford Haven. In conclusion, an additional increase in temperature may result in this species breeding more readily, which could have an effect on native communities. However, the thermal discharge from the power station will only affect temperature over a limited area of the sea bed (table 5.13) and its impact on Pacific oyster recruitment in the SAC will be negligible compared to the general predicted impact of climate change on Pacific oyster recruitment. It is possible that some temperature tolerance species like eels and bass, will not avoid the plume and in fact may prefer the area. In these cases there is a potential for an increase exposure to area of higher levels of TROs. This potential risk and final conclusion of negligible risk, has been discussed earlier in section 5.1.5.2 Temperature controls the rate of fundamental biochemical processes and thereby plays a role in organism attributes that can affect development and survival rates. The increase in metabolic rate with temperature explains substantial among-species variation in life-history traits, population dynamics and ecosystem processes (O’Connor, et. al., 2007). Virtually all biological structures and processes are affected by temperature. For this reason, temperature-adaptive variation occurs, resulting in widespread different thermal limits among species (Somero, 2002). Thus, species and communities found within estuarine areas are particularly well adapted to withstand temperature changes. Phytoplankton provides a food supply to upper trophic levels, and any modification in its structure and/or dynamics (i.e. phenology, size structure, species composition) may trigger changes in the ecosystem functioning. Guinder et. al. (2010) concludes that the changes in the phenology and composition of the phytoplankton are mainly attributed to warmer winters and the extremely dry weather conditions evidenced in recent years in the Bahı´a Blanca area in Argentina. Changing climate has modified the hydrological features in the inner part of the estuary (i.e. higher temperatures and salinities) and potentially triggered the reorganization of the phytoplankton community. However, this refers to a different suite of phytoplankton species from that found within Milford Haven. Owing to their eurythermic characteristics, zooplankton estuarine species usually display more tolerance to this type of stress than do species from other more stable marine environments. Plankton is expected to be more sensitive to thermal stress during the development stages, and meroplanktonic forms of benthic species (crabs, other crustaceans and invertebrates) are similarly expected to be less tolerant to cooling system stress factors than adults. Species react differently to the thermal stress caused by power plants in accordance with their degree of acclimation to natural temperature variations and their tolerance range (Hoffmeyer, et. al., 2005). Langford et. al. (1998) reported on adverse changes in the flora and fauna of soft sediment and rocky shore biotopes in the immediate vicinity of a plume, within 0.5km of the discharge caused by the temperature of the discharge, but also biocide and erosion would contribute to this effect. Information from these references has been considered when reaching our conclusion.

- 95 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Chio et. al. (2002) state the effects of high temperatures (up to 27.2oC in summer) were not as pronounced as those of chlorination, however the results indicated the thermal effluents appeared to have inhibitory effects on bacterial production and on heterotrophic nanoflagellate grazing rates and abundance, although this improved with increasing distance from the outfall. In a comprehensive study of Diablo Cove, in the United States of America, Schiel et. al. (2004) investigated the effect of a thermal discharge (temperature differential of 11oC) on species abundance. In this instance the monitoring data on the discharge demonstrated that very little was discharged, other than heated water. The result of the study demonstrated that an increase of 3.5oC of sea water temperature induced by the thermal discharge, over a 10 year period, resulted in significant community wide changes in 150 species of algae and invertebrates relative to adjacent control areas experiencing natural temperatures. However, by contrast, grazing gastropods showed a positive response to temperature, which is most likely a response to thermal tolerance and recruitment dynamics. However, these populations were also affected by several El Nino Southern Oscillation warming events and reflect a completely different suite of species. This information has been considered to be relevant to this assessment, but does refer to a different suite of biota and communities to that found within Milford Haven. Although not cited separately, migratory fish are part of the ‘estuaries’ feature, so need to be taken into account. Salmonids often prefer to migrate in the surface layers, which will be the layer most impacted by warm water and most likely to cause temperature stress to the fish and/or a barrier to successful migration67. However, EA fish technical experts have concluded that on the basis of modelling data, it is expected that salmonids will use the deeper North shore waters as a route to and from the Cleddau rivers. Although surface orientation has been reported, it is not imperative and if salmon/ sea trout can avoid warm water they have the opportunity to do so. Scale Table 5.13 and figure 5.12 provide an indication of the extent and scale of impacts. The footprints show the areas where the threshold is exceeded at any time in the spring neap tidal cycle. The extent of the cumulative thermal impact is demonstrated in figure 5.12. The areas of the footprint are much smaller compared to that of the MAC, especially at the surface75.

Table 5.13 Area of estuary feature within +2°C footprint

Interest Area (ha) Area within +2oC footprint feature Sea surface Sea bed Ha % Ha % Estuary 5472.5 CCW 543.5 9.9 135.4 2.5

212 (95 3.9% (95 89 1.6% percentile) percentile) (95 percentile)

The proposed thermal discharge exceeds +2°C with the mixing zones covering 9.9% of the ‘Estuaries’ feature at the sea surface (2.5% at the sea bed). Up to 543 hectares are affected (‘Estuaries’ feature at the sea surface). It should also be remembered that temperatures within the mixing zones (+2°C footprint) will on occasions reach up to +8.7°C above current background). However, for 95% of the time the predicted areas will be considerably less at 3.9% (212 Ha) and 1.6% (89 Ha) respectively.

67 EA Southern Region Marine Team. Report 10289. Final with update 24 April 2011. Pembroke Power Station – Cooling Water Discharge (thermal and TRO impacts). - 96 - Figure 5.12 Extent of the cumulative thermal impacts on the estuary feature (sea surface and sea bed), indicating the 0.2°C change which triggered further investigation in this appropriate assessment, and the extent of the 2°C exceedance plume

5.2.6.2 Large shallow inlets and bays

Sub tidal, intertidal and pelagic habitats within the shallow inlets and bays feature are subjected to elevated temperatures from the cooling water discharge. Table 5.14 and figure 5.12 provide an indication of the extent and scale of impacts. Scale As the Milford Haven waterway part of this feature is wholly encompassed by the estuaries habitat, there is also some overlap with mudflats and sandflats. As such the discussion for this habitat is covered in section 5.2.6.1 estuaries

Table 5.14 Area of large shallow inlets and bays feature within +2°C footprint

Interest feature Area (ha) Area within +2oC footprint from CCW Sea surface Sea bed Ha % Ha % Large shallow inlets 22091.1 543.5* 2.5 135.4* 0.6 and bays *However, for 95% of the time the predicted areas will be considerably less.

- 97 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.2.6.3 Mudflats and sandflats not covered by seawater at low tide

The cooling water discharge will flow directly onto mudflat habitat. The distribution of species within this feature will have required physical, and sometimes biological limits, as well as physiological tolerance limits and will only be found within those limits. Where a habitat is very restricted in occurrence, the distribution of a species will reflect occurrence of the habitat and may not be primarily influenced by physical conditions such as temperature (except where the occurrence of the habitat changes as a result of temperature change) (Hiscock et. al., 2004). Temperature elevations in excess of 2oC will occur over an area reaching from the upper to lower intertidal shore across Pwllcrochan flats at some stage during the tidal cycle. Benthic species are particularly susceptible to the effects of a thermal discharge, since they have limited ability to escape: many of them are sessile or sedentary and even many errant species move little during their life-time (Bamber & Spencer, 1984). The response of mobile species and populations to thermal stress could be quite variable according to their geographic and bathymetric distribution (Lardicci et. al., 1999). Each of these factors has thus been considered within this assessment. Heating and cooling of mudflats and other intertidal areas can cause strongly fluctuating temperatures on a tidal/diurnal timescale. The effects are most marked where intertidal areas form a high proportion of the total estuary area in summer. Particularly in estuaries where freshwater run-off and exchange is low and the low water of high range tides occurs around mid-day (i.e. those that lead to the greatest exposure of intertidal area in the early afternoon). On clear, still summer nights significant re-radiation of heat can occur, at times resulting in local ground frost. Turnpenny & Liney, 2007 reported daily fluctuations in estuaries result from a combination of solar heating during the day, tidal movement, over heated or cooled intertidal substrata and the mixing of rivers and sea waters. Spencer (1970) recorded a 15oC variation in the near-surface temperature of a Milford Haven mudflat over a 48hr period in September 1968 but only 3oC in March of that year However, temperatures at the surface of the mudflats and sediments will exceed this significantly during high summer when air temperatures may reach 30–35oC but the biota within the sediments typically survive such transient phenomena although survival may be dependent on the flooding tide covering the mudflat with comparatively cool water which can readily absorb heat from the sediments. In addition Walters (1977) found a natural annual temperature range of -4.5 to 32.5°C in the littoral zone of the Medway. Hiscock et. al. (2004) found that when sea temperatures have risen by as much as 1oC, in relation to climate change, there have been significant local changes in the distribution of intertidal organisms. However a study on Moss Landing power plant (2006) did not find any significant impacts of the power plant thermal discharge on intertidal and shallow subtidal faunal communities. Although the impacted substrate is sandy shore as opposed to the intertidal mudflat in Pembroke, it is also important to note that the heated effluent is discharged in 7 metres of water and the maximum temperature differential is 2oC above ambient. Also Lardicci et. al. (1999) reported analysis of benthic communities which showed that heat effluent seemed not to influence assemblage structure or the spatial distribution of the study taxa. However, the response of different species and populations to thermal stress could be quite variable according to their geographic locations and bathymetric distribution.

- 98 - The sensitivity of the intertidal biotopes68 to thermal changes is illustrated in figure 5.13, with the extent of the sea bed exceedance over 2oC (2006 model). This demonstrates that the sensitivity of thermal effects is either low or very low. However, this describes an effect at 2oC whereas in reality the temperature will be higher in areas closer to the outfall (maximum 8.7oC temperature rise). However, high temperatures and exposure will be intermittent primarily due to the tidal variation in currents and water levels along with the buoyancy of the thermal plume. With this in mind figure 5.13 below represents the indication of species richness within the biotope, and suggests that the biotope is either unlikely to change or will undergo a minor change. The specific stressors forming the basis for the MarLIN classification are continuous exposure to +2°C or a 3 day change of +5°C, the classification and associated literature review is a convenient basis for structuring the expert judgement on effects to be anticipated from thermal plume exposure, that includes areas experiencing higher maximum temperature rises, albeit intermittently. The MarLIN literature review includes a range of information on temperature exposure relevant to the biotope, including lethal temperatures. Minor decline is defined by MarLIN as a loss of less than 25% of species. Most biotopes are relatively tolerant to an increase in temperature, however given the long term nature of the potential impact, the biotopes are sometimes unable to recover69, so inevitably the area in the immediate vicinity of the outfall will undergo a decline in species richness, for example Fucus spiralis and Pelvetia canaliculata which are highly sensitive to changes in thermal regime (MarLIN70).

68 Biotope: the physical habitat and its biological community: a term which refers to the combination of the physical environment and its distinctive collection of species. 69 Part II, Chapter 7- Ecological Effects of Operational Physical Marine Changes, pg 13. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 70 Web link: www.MarLIN.ac.uk - 99 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 5.13 Sensitivity of biotopes to thermal impacts (RWE CES 2010, figure 117)

The biotopes present within the 2oC maximum temperature contour include a mosaic of shingle and alga in the lower intertidal and mud in the upper intertidal. It is expected that the sensitivity of these biotopes is low or very low, which is a view also reflected in many Regulation 33 packages. CCW have expressed concerns about two particular typical species of the mudflat feature, with respect to the change in thermal regime. These include estuary rag worm Hediste diversicolor and bivalve Macoma baltica. MarLIN states however, that the geographic range of the estuary rag worm suggests that it is tolerant of a range of temperatures and a long term chronic temperature increase or decrease is unlikely to have an adverse effect on UK populations71. With respect to the bivalve Macoma baltica, there is evidence that due to its relatively low tolerance to elevated temperatures it may be one of the first important marine species in temperate coastal areas to suffer from a warming climate. At lower latitudes, the southern edge of its range recently shifted several 100s of km to the north. Beukema et. al. (2009) conclude that elevated temperatures negatively affect population dynamics of M. balthica in a number of ways, i.e. via recruitment or mortality as well as growth. With further long-term temperature increases expected, it is likely that this species may well disappear from the estuary attributed to the consequence of climate change. However this can be considered a natural process, that may well occur without the proposed power station being present.

71 Web link:www.MarLIN.co.uk - 100 - In some cases the thermal discharge could influence the seasonal dynamics of the communities rather than the spatial distribution and the structure of the assemblages (Dinet et. al., 1982; Yi, 1987, in Lardicci et. al., 1999). Therefore, it is clear that the physiological nature of benthic organisms (apart from M. balthica) renders them more tolerant to changes in temperature in the short term. Long term temperature variation in the vicinity of the outfall may result in biological changes to the typical species and any change will vary greatly from species to species. For example, those within the higher intertidal areas would be expected to have wider tolerances to a variety of physical parameters than those in the lower intertidal area. Also amongst species living on or near the seabed, fish are likely to react in concert with temperature change as they are mobile. Crustaceans will also respond fairly rapidly if it is temperature that controls adult distribution (Hiscock et. al., 2004). However, benthic invertebrates living in the intertidal area of the cooling water plume would be expected to be affected due to their relative lack of mobility. It is also expected there would be an effect on breeding species that require a low temperature ‘trigger’ to reproduce (Hiscock et. al., 2004). Whilst temperature increase caused by the cooling water discharge is not lethal (a temperature greater than 35oC is considered likely to result in lethal effects) if exposure is prolonged, sub lethal effects may occur. It is expected there will be a loss of temperature sensitive species or degradation of the local population structure and dynamics within the plume. For this reason, the thermal limit on the cooling water discharge is proposed to be 30.4 oC. Scale Table 5.15 provides an indication of the extent and scale of the impact. The combined area of exposure to an exceedance as a MAC over the neap-spring tidal cycle on intertidal area is demonstrated in figure 5.13.

Table 5.15 Area of intertidal mudflat and sandflat feature within +2°C footprint72

Interest Area (ha) Area within +2oC footprint feature Sea surface Sea bed Ha % Ha % Intertidal 1778.6 183.1* 10.3* 99.9* 5.6* mud and sandflats * However, for 95% of the time the predicted areas will be considerably less.

The proposed thermal discharge exceeds +2°C with the mixing zones covering 5.6% of the ‘mudflats and sandflats’ feature (10.3% at the sea surface overlying the flats). Up to 99.9 hectares of the ‘mudflats and sandflats’ feature are exposed at the sea bed48. However, smaller areas will be exposed to different temperature rises for different durations, refer to table 2.1.1 of report ENV/463/201173. The MarLIN approach looks at continuous exposure to temperature increases of 2oC to ascertain sensitivity of the biotopes. Therefore, if we consider the area with a mean temperature increase of 2oC, this equates to 9.23 ha of sea bed exposure, including the dredged channel and some areas outside the mudflats and sand flats feature (9.23 ha is a maximum 0.52% of the mudflat feature).

72 See footnote 83. 73 Pembroke CCGT cooling water thermal plume and the intertidal benthos of Pwllcrochan Flats: summary of and supplementary information, RWE ENV/463/2011, March 2011. - 101 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

5.2.6.4 Reefs

The indication of likely significant effect as a screening tool is determined where there is a mean temperature change of more than 0.2oC in the water of the SAC. In the previous (PPC stage 1) assessment the maps showing the extent of the reef feature in Pembrokeshire Marine SAC demonstrated that there was no habitat that would be exposed to a temperature rise above 2oC. However, maps provided by CCW in 2010 now show a small area of reef on the seabed that could be exposed to an increase of temperature over the 2oC guideline standard at certain states of the tide, refer to figure 5.14 and table 5.16. However the model assessments have found that only 0.01% of the area of the reef would overlap with the thermal plume at the seabed. This is primarily because it is a buoyant plume which remains on the surface for a considerable distance. Reefs are dynamic environments; they can be many different structures that include those formed of rocks and stones to biogenic reefs that are formed from living creatures. Each type of reef supports a different community of animals. Near shore and intertidal reef extend throughout the Milford Haven ria, this includes both large, extensive and smaller discrete areas of reef (CCW, 2005). The reef features, especially in the mouth of the Pennar Gut, will be accustomed to the effects of the tidal stream and changes in temperature due to exposure from freshwater flowing down the Pembroke River. With respect to those reef structures that are sub tidal in the Pennar mouth area, they are some distance from the outfall and the temperature will have dissipated considerably at the bed in this location.

Table:5.16 Area of reef feature within +2°C footprint74

Interest Area (ha) Area within +2oC footprint feature Sea surface Sea bed Ha % Ha % Reefs 41006.6 85.2* 0.2* 4.4* 0.01*

*However, for 95% of the time the predicted areas will be considerably less.

74 See footnote 49. - 102 - Figure 5.14: Location of reef feature in relation to the thermal exceedance on the sea bed.

5.2.6.5 Grey seal

As highly mobile top predators the grey seal is very dependent upon the health of lower trophic levels. They are widely distributed within, and beyond the SAC, however, only their pupping and regular moulting sites may be determined with precision. There is thus potential for an in-direct effect on this feature with respect to effects on prey items. However, the seals themselves are mobile and have a very good swimming ability and will be able to avoid undesirable water conditions. The diet of the grey seal varies by location, though they are largely demersal or benthic feeders (Hall, 2002). In some areas, the food consumed can be over 70% sandeels. However, in the UK they also feed on a wide variety of fish, crustaceans and cephalopods. A study of the diet of grey seals in west Wales found whiting and flatfish accounting for about 70% of their diet, with herring and, surprisingly, dragonet making up most of the rest (Strong, 1996). The sea is a complex ecosystem consisting of other predators including larger fish, seabirds, cetaceans and humans. Research has shown that of all these groups, seals consume the least fish, and although much of it is of commercial importance, their diet is very mixed. In undisturbed systems seals feed on a variety of fish and have evolved a complex web of feeding relationships with their prey, switching between species if they become scarce, and allowing recovery of depleted species (Cardigan Bay Management Scheme, 2008).

- 103 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.2.6.6 Anadromous fish

Our literature review found a number of papers relevant to our assessment of the potential effects on lamprey and shad. We found lamprey and shad can be sensitive to temperature variation, particularly when they migrate upstream. They are also sensitive to oxygen depletion. According to Hardisty & Potter (1971), river lamprey spawning in British rivers starts when the water temperature reaches 10 -11oC in March or April and the critical spawning period normally lies between 8.5 to 12oC. An increase in temperature may encourage earlier lamprey migration upstream. Farmer et. al. (1977) demonstrated that adult sea lamprey survived and grew in a wide range of water temperatures (4-20oC), with temperatures of 17-19oC having been reported by Hardisty (1986) for some British rivers. Peak migration usually coincides with temperatures that remain above 10oC and continues until temperatures reach 18oC. Therefore an increase in temperature may encourage earlier migration upstream to the river, however this would not affect the onset of spawning or the rate of juvenile development. Studies of the upstream migration of river lamprey for the deep sections of the lower River Derwent and tidal Ouse carried out for the review of consents, found migrating lamprey appear to prefer the main channel rather than the banks75. However, they may occupy marginal habitats within the rivers, such as overhanging banks, as suitable daytime resting sites. The change in the estuary thermal regime is therefore considered unlikely to represent a barrier to migration. Twaite and allis shad are not known to spawn in the Cleddau catchments, but they use the marine waters outside the estuary to migrate to the Tywi catchment where they are known to spawn. Upstream migration appears to be triggered by temperature, with twaite shad migration occurring at between 10 -14oC (Maitland & Hatton Ellis, 2003). But as the Milford Haven waterway is not a spawning migration route for shad the increase in thermal regime in the estuary is not likely to have an effect. However, if some shad were to pass into the estuary it is unlikely they would be affected, for the same reasons stated above for lamprey.

5.2.6.7 Otter

It has been identified that there is potential for an in-direct effect on otter prey items from the change in thermal regime. However, otters are mobile and not restricted to one habitat type and display opportunistic feeding behaviour. A report by Parry (2008) concluded that the occurrence of freshwater fish and non-fish prey, in the spraints of otter living in Pembrokeshire, demonstrated the flexibility of otter foraging techniques, which are effective at catching a wide diversity of prey in a range of different habitats. In addition, Liles (2009) demonstrated that otters are now using the open coast and islands of the Pembrokeshire Marine SAC, and are travelling in the sea away from coastal streams (often for distances of several kilometres) to forage in the marine environment.

75 Humber European Marine Site, Habitats Directive: stage 3 Review of Consents, Water Quality Appropriate Assessment. - 104 - 5.2.7 Summary of the potential effects of change in thermal regime Evidence

The applicant proposes to use a ‘once-through’ main cooling water system (MCWS) which will use sea water to cool the exhaust steam from the turbines. The MCWS will pass cooling water abstracted from Pennar Gut, east of the power station site, through the steam turbine condensers before discharging the warmed water directly to the Milford Haven waterway to the north, via a dredged discharge channel. RWE have committed to designing the power station to be Combined Heat and Power (CHP) ready, such that if the opportunity arose, waste heat could be used rather than discharged into the Milford Haven waterway. We have ascertained that the applicant is employing BAT and we agree with the evidence supplied by the applicant. We have taken into account the prevailing environmental conditions through long term field measurements of temperature fluctuations. There are currently no statutory thermal standards for estuaries. UKTAG (2008) states that for estuaries and coastal waters there is inadequate information to link ecology generally to the complex thermal structure created by a thermal gradient. The ‘BEEMS Science Advisory Report Series (2010) No 008 (BEEMS Expert Panel) - Thermal standards for cooling water from new build nuclear power stations’, confirms that adverse effects of cooling water (CW) outfalls are restricted to an area close to the plume; that temperature rises up to 3°C appear to be tolerable and that resulting temperatures less than 27°C have no clear deleterious impact on species in the receiving waters. However, in the longer term, changes in the local community may result as species with differing tolerances of elevated temperature show differing survival, growth and patterns of reproduction from those expressed under ambient conditions. Populations that persist in the receiving area of a heated CW effluent will acclimate to those new local conditions and may adapt in response to them. Superimposed on these changes, however, are community changes caused by species distribution alterations as the result of climate change. Expert technical judgment

Our literature search found that changes to the marine environment by the discharge of heated effluents may vary greatly as a function of the quantity of heat discharged and the climatic, hydrological and biological features of the environment. For example Langford et al.,(1998) suggests there is ample evidence of changes in life histories, behaviour and distribution of species of algae, invertebrates and fish within near field areas of thermal plumes. However, these same organisms that have become adapted to estuaries, have great tolerance to rapid changes in temperature and salinity that are helpful in resisting external forces. Findings from Somero (2002) and O’Connor et al.,(2007) indicate that the estuary within the immediate vicinity of the cooling water discharge will continue to support species that are specifically adapted to temperature variation. It was also found that whilst there could be negative effects, an increase in temperature can increase reproductive output and juvenile survival for southern/lusitanian species.

- 105 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Individual feature conclusions

Estuaries Large shallow inlets and bays Mudflats and sandflats not covered by seawater at low tide.

The modelling predicts that proposed thermal discharge exceeds +2°C for these features:- ƒ Estuary, 9.9% (543 Ha) of the sea surface and 2.5% (136Ha) of the seabed. However, this is the largest predicted extent, as for 95% of the time the predicted areas will be considerably less at 3.9% (212 Ha) and 1.6% (89 Ha) respectively; ƒ Mudflats and sandflats, 10.3% (183.1Ha) of the sea surface and 5.6% (99.9Ha) of the seabed; ƒ Large shallow inlets and bays, 2.5% of the sea surface (543.5Ha) and 0.6% (135.4Ha) of the seabed. However, these are the largest predicted extent of the precautionary model, as for 95% of the time the predicted areas will be considerably less, as shown with the figures for estuary. The MarLIN assessment indicates that the sensitivity of the biotopes to thermal effects within the plume is either low or very low. However, this describes an effect at 2oC whereas in reality the temperature will be higher in areas closer to the outfall (maximum 8.7oC temperature rise). However, high temperatures and exposure will be intermittent primarily due to the tidal variation in currents and water levels along with the buoyancy of the thermal plume. It concludes that the biotopes are either unlikely to change or will undergo a minor change, for example a decline in Fucus spiralis and Pelvetia canaliculata which are highly sensitive to changes in thermal regime (MarLIN). Long term temperature variation in the vicinity of the outfall may result in biological changes to the typical species, however these changes will vary greatly from species to species. Benthic invertebrates living in the intertidal area of the cooling water plume would be expected to be affected due to their relative lack of mobility. It is also possible that there would be an effect on breeding species that require a low temperature ‘trigger’ to reproduce (Hiscock et. al., 2004). However, Bamber and Spencer (1984) found that at the Kingsnorth power station, in operation, less tolerant subtidal species were suppressed but, the thermally tolerant intertidal species were able to exploit the conditions to form dense populations, considerably denser than at the control site. The concerns from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, were that:- Typical species include those species typical of the areas impacted by the discharge, so would include for example plankton in the water column, fish in the water column, typical muddy benthos species, typical mixed sediment benthos species, typical intertidal species, typical reef species etc. The intertidal mudflats between Pennar Gut and Pwllcrochan will be subject to water temperatures 2 degrees C or more above ambient - see fig.6.5.9 in Consolidated Environmental Statement. Typical species include those species typical of the areas impacted by the discharge, so would include for example estuary rag worm Hediste diversicolor and bivalve Macoma baltica. For the reasons listed within this whole section, we do not believe the localised effects from the thermal plume will have an adverse effect on site integrity.

- 106 - CCW’s condition assessment indicates that these features are in unfavourable: declining conservation status. We believe the main reasons for this, from information supplied by CCW, are principally due to nutrient emission and habitat loss due to dredging. The discharge of the thermal plume will not exacerbate these causes of unfavourable conservation status, nor undermine measures to return it to favourable conservation status. In principle, this is due to the nature of estuarine environments which are very resilient and adaptable, due to the wide variety of environmental factors that they experience. For example in the document Re-establishment of intertidal rocky surveillance (N.Meiszkowska, February 2011) ‘The surveys found that despite an increase in non-native species, which is likely to have resulted from the high volume of international shipping and recreational vessel traffic, it ‘did not appear to have significantly altered ecosystem structure and function at these sites’. Considering that this is an area which has suffered from Sea Empress oil spill in 1996, this is an excellent demonstration of how robust the Pembrokeshire Haven ecosystem is.’ Reefs

There is only a very small overlap between the thermal plume and the area of the seabed containing the reef feature, because the thermally buoyant plume is at the sea surface and does not extend this far along the seabed. The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘Both intertidal and sub littoral reef will be affected by temperature rise. Due to the lack of overlap we do not consider the reefs to be affected.’ CCW’s condition assessment indicates that this feature is in unfavourable : no change conservation status (2006). We do not consider that the thermal plume will exacerbate unfavourable conservation status, nor undermine measures to return it to favourable conservation status. Grey seals and Otter

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘Prey availability will be affected by increase of temperature (9 degrees C increase at outfall)…’. We have considered that grey seal and otter are currently in favourable conservation status, and that the risk of bioaccumulation and reduction in prey is negligible. Any contaminants present will be below concentrations that are potentially harmful to seals and otters physiological health and reproductive capability. This is based on our findings on bioaccumulation, the latest literature searches and background marine monitoring. Some minor change may occur to the prey species in the localised vicinity of the discharge, but as this change may actually increase the abundance of some prey species it is considered that the overall effect will be negligible. Combining this with their wide feeding area, both within and outside the plume, we do not consider it will worsen the favourable conservation status. Anadromous fish (allis and twaite shad, sea and river lamprey)

We have ascertained that the dissolved oxygen levels will remain within safe limits for all life stages as recommended by UK TAG (2008). Migrating lamprey prefer the main channel rather than the banks, however, they may occupy marginal habitats within the rivers, such as overhanging banks, as suitable daytime resting sites. As the Milford Haven waterway is not a spawning migration route for shad the increase in thermal regime in the estuary is not likely to have an effect

- 107 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that the ‘Thermal plume and Total Residual Oxidant may affect shad and lamprey range and alter the distribution of prey species’. For the reasons listed in this section we do not consider that they will be affected by the thermal plume. CCW’s condition assessment indicates that the anadromous fish feature is in ‘unfavourable: no change’ condition. Due to the reasons mentioned, we do not consider that the thermal plume will exacerbate the unfavourable condition status, nor undermine measures to return it to favourable conservation status. Predicted physical /chemical/biological effects on the ecology

The +2°C MAC assessment standard is exceeded at the sea bed in a region extending approximately 1.5km seaward and 1.2km landward of the outfall and up to approximately 750m offshore. The +2°C MAC assessment standard is exceeded at the sea surface in a region extending approximately 4km seaward, 2km landward and approximately 1.2km offshore. The thermal impact (+2°C increase), is estimated to only affect a daily volume of 0.26% of the tidal volume of the Milford Haven at average equinox spring tides. The modelling shows that the largest modelled thermal mixing zone occurs on spring tides and covers up to 3.5% of the inter-tidal bed near the outlet, however at all other times the mixing zone is smaller. As a result a much smaller area of sea bed close to the cooling water outlet will experience a mean temperature rise of ≥ 3ºC. There is a significant reduction in affected area from a maximum temperature threshold of +2°C to a maximum of +3°C and the area is almost exclusively intertidal. Only a small area, experiences a mean temperature rise of ≥+5°C. For example the area of exceedence of 5°C is 51.78 ha as a maximum, 42.30 ha as a 98 percentile and almost zero as a mean. The majority of the cross sectional area, including all of the north side of the Haven, does not exceed the +2°C maximum allowable temperature rise at the edge of the mixing zone. For Dissolved Oxygen (DO), the minimum readings for all sample points within Milford Haven were greater than 5mg l-1, so it was not necessary to calculate 95 percentile values. In the area of the plume, even allowing for a precautionary temperature rise of up to 8.7oC would not result in DO readings below 5mg l-1. As such, dissolved oxygen levels will remain within safe limits for all life stages as recommended by UK TAG(2008). The temperature within the Haven, typically ranges from 5-18°C and can reach higher temperatures under more extreme weather conditions. The dredged channel at the outlet (not part of this permit) will mitigate effects on the seabed at certain tidal states, as the warm discharge plume will flow along the channel to deeper water. Sensitivity/resilience to that hazard.

Based upon internal and external advice, the extensive literature search and all the information from the applicant, we have concluded that there will be some changes to the local species community adjacent to the thermal plume. This is as a result of the differing tolerances to temperature in the species found within the vicinity of the plume. They will show differing survival, growth and patterns of reproduction from those expressed under ambient conditions. Populations that persist in the receiving area of the effluent will acclimate to those new local conditions and will adapt in response to them.

- 108 - Despite these localised predicted effects, in our opinion the potential effects of the thermal plume would not adversely affect the ecological functioning of the sites. The typical species found within the mixing zone are widely found within the rest of the protected site outside of the mixing zone. There is no acute effect occurring which would adversely effect the site integrity of the protected features. As such, even though there will be a temperature change over a relatively small area of seabed and sea surface, it is considered that the scale of this impact, will be negligible, when considered as an ecosystem approach as outlined in the Marine Strategy Framework Directive (see page 17 of EC Guidance on the implementation of the EU nature legislation in estuaries and coastal zones). Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each sub-element of the COs, using the information supplied by CCW in Appendix 3 ‘In-combination matrix provided by CCW 280610’. They have not been repeated in this conclusion to save space within this document. Unfortunately, the way that CCW have phrased some of these elements means that no project with any emission other than a remedial project, could be authorised without failing to meet the individual elements of favourable conservation status. As a result we have found that the COs are not compromised but as some of the COs sub elements are not feasible or achievable - more aspirational, then some of the sub elements of the COs are not met. Remaining doubt

Initially there was doubt about the scale of the thermal plume. The applicant, as requested by the Environment Agency, undertook additional modelling, to identify the extent of the thermal plume, at all tide states, as well as peak load operation, a flow rate of 40m3s-1 and cross-station temperature rise of +7.6°C. We have ascertained that this is now the best available information and that the final model used is suitably precautionary for this appropriate assessment. It should be noted that RWE have informed the Environment Agency that they intend to conduct temperature monitoring within Milford Haven waterway. This will include the addition of temperature monitoring probes on the surface and the bed of the estuary. Welsh Government Marine Consents Unit have confirmed that the monitoring equipment will not cause an obstruction or danger to navigation, or cause a significant impact on Milford Haven Waterways. The information received to date indicates that this would be non-intrusive and necessary for management of the Pembroke Marine SAC. It has thus not been included within this in combination assessment. This monitoring programme complies with the European Commission guidance ‘Implementation of Habitats Directive in Estuaries & Coastal Zones - EU Guidance (January 2011).’ Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain, in particular, error margins associated with any modelling of the precise location and precise shape of predicted temperature, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

- 109 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.2.8 Site integrity implications with respect to change in thermal regime Overall the Environment Agency, after considering fully the conservation objectives for Pembroke Marine SAC ascertains that there is no adverse effect alone on site integrity. This is summarised in table 5.18.

- 110 -

Table 5.18: Initial conclusions on site integrity, assessing the impact of the thermal regime in relation to the conservation objectives of special interest features and the site.

Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be changes 3) Is the 4) Will there be 5) Will there be a 6) Will the natural 7) Will there be which the SAC of annex 1 to the composition of the conservation status interruption or direct effect on range of the indirect effects has habitats (or habitats for which the site of the feature degradation of the the species within the on the Been selected composite was designated? (e.g. unfavourable? physical, chemical or population of the site be reduced populations of features) be reduction in species biological processes species for /likely to be species for reduced, structure, abundance or that which the site reduced for the which the site sufficient to diversity that comprises support habitats and was designated foreseeable was affect the site the species for which the or classified, future, sufficient designated or integrity? habitat over time, site sufficient to to affect the site classified due to sufficient to affect the site was designated or affect the site integrity? loss or integrity?) classified, sufficient to integrity? degradation affect the site integrity? of their habitat (quantity/quality), sufficient to affect the site integrity? Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reef No No Yes No n/a n/a n/a Grey seal n/a n/a No No No No No Anadromous fish n/a n/a Yes No No No No Otter n/a n/a No No No No No

- 111 - 5.3 Nutrient enrichment

This section has been amended to take account of:

ƒ a revised environmental emissions assessment for aqueous discharges from Pembroke Power Station76; ƒ a report on possible effects of phosphorus, nitrogen and thermal discharges on eelgrass and macro-algal growth in Pembroke River (Wither 2011); ƒ a report by Aldridge & Painting (2011) for Cefas (Centre for Environment, Fisheries and Aquaculture Science) on the modelling of nutrient impacts in the Milford Haven Waterway; and ƒ comments from CCW on a previous version of the AA.

This assessment follows the key steps shown below:

5.3.1 Possible effects of increased nutrients

Nutrient enrichment can result in indirect effects on species or communities due to a proliferation of plants such as phytoplankton or macro-algae. Previous studies(Edwards, (2005), Mitchell (2009),and Robinson (2009) have indicated that nutrient concentrations in the Milford Haven waterway are higher than those found in coastal waters around Pembrokeshire and that the waterway is hypernutrified compared to coastal standards. There is no evidence that this is causing sustained blooms of phytoplankton in the water column, possibly because other factors such as turbidity are restricting phytoplankton growth. However, there is widespread and sometimes dense occurrence of seasonal inter-tidal macro-algal blooms (mainly Enteromorpha spp.) on inter-tidal mudflats and sandflats within sheltered bays and inlets.

76 RWE Npower (2011) Environmental Emissions Assessment for aqueous discharges from Pembroke Power Station. Report number ENV/476/2011, October 2011, Issue 4 - 112 - Adverse impacts of this growth, identified by CCW(2009), include:

ƒ Frequent occurrence of surface anoxia; ƒ High levels of organic detritus; ƒ ‘Bacterial’ blooms; ƒ Release of hydrogen sulphide; ƒ Drifting rafts of detached macro-algae; ƒ Green tides’ deposited on shore, smothering salt meadows and creating amenity issues; ƒ Dense algal mats likely to inhibit bird feeding; ƒ Stressed/’polluted’ biological communities.

Of particular concern is the risk of dense algal mats causing smothering of inter-tidal eel grass (Zostera noltii) beds, a typical species within the Pembrokeshire Marine SAC. Approximately 75% of the inter-tidal eel grass occurring in the Milford Haven Waterway is located within the Pembroke River Estuary (also known as Pennar Gut), approximately 2 km from the proposed point of discharge. This estuary also contains opportunistic green macro-algae (Enteromorpha) which can grow excessively and smother mudflats and eelgrass. The macro-algae is not extensive in this area, but where it grows it produces a large biomass (average over 1000g/m2). Other potential impacts of increased nutrients include increased turbidity (due to increased phytoplankton), reduced light (due to increased macro algae), reduced sediment oxygen and effects on biota due to diurnal variations in dissolved oxygen in the water. Habitats sensitive to reduced light as might be caused by increased turbidity, such as maerl and eelgrass, occur predominantly in the lower estuary. The estuary’s maerl bed (the only live bed left in Wales) is already in poor condition following substantial impacts from other recent developments in the estuary (CCW 2011).

5.3.2 Current nutrient status of the Milford Haven Waterway

Pembroke Power Station is situated on the border between the Inner and Outer Milford Haven water bodies. It will abstract from the Inner water body and discharge to the Outer water body, but could potentially have an impact on either water body depending on the direction of the tide. Both these water bodies were classified as “Moderate” in 2010 according to Water Framework Directive standards. Both water bodies achieved a High standard for phytoplankton, but were less than Good for Dissolved Available Nitrogen (DIN). The macro-algae results were Moderate and Good for the Inner and Outer water bodies respectively. Phosphorus results are not used in the classification. Nitrogen is normally the limiting nutrient for algal growth in coastal waters, while phosphorus is normally the limiting nutrient in freshwater. Factors limiting algal growth in estuaries are more difficult to identify, due to temporal and spatial variations in salinity, nutrient ratios, water depth, turbidity and other factors. This is especially true for macro-algae, as a complex range of interacting factors are likely to influence its growth, including available inter-tidal habitat and nutrients within the sediment. Modelling studies in the Milford Haven waterway have previously indicated that phosphorus is the main limiting nutrient for phytoplankton growth, especially in the upper estuary (Edwards 2008), where freshwater dominates. Studies by Cefas (2004) in EA Southern Region have, however, shown significant correlations between nitrate concentrations and macro-algal growth in estuaries on the south coast of England.

- 113 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Nitrogen and phosphorus are utilised for algal production at an atomic ratio of approximately 16:1 (Redfield 1958) although this ratio may vary between species. Therefore, if the ratio of N:P in water differs from 16:1, the nutrient in the shortest supply is likely to limit algal growth. N:P ratios in the Milford Haven waterway are highly variable, both spatially and temporally, and may be much greater or less than 16:1. By applying a method devised by Neill (2005) it may be possible to account for some of this variability and determine which nutrient is likely to be most limiting at any given salinity. This method involves overlaying graphs of available nitrogen versus salinity and available phosphorus versus salinity with the vertical scales for N and P set at a ratio of 16:1; whichever nutrient has the lowest trend line is likely to be the limiting nutrient. Fig 5.15 shows the application of Neill’s method to data from all sampling points within the Milford Haven Waterway. From this it can be seen that phosphorus is likely to be the limiting nutrient for salinities up to around 32ppt, which is similar to the salinity at the proposed discharge point for the power station (mean 31.5ppt). This supports the evidence that algal growth could be limited by either nitrogen or phosphorus in the vicinity of the power station discharge, with a possible tendency towards phosphorus limitation.

Figure 5.15 Graph showing available nitrogen and phosphorus versus salinity for all sampling points in the Milford Haven waterway from 2000 to 2011.

N P 5 Linear (N) 0.3 4.5 Linear (P) 4 0.25 3.5 0.2 3

2.5 0.15 P (mg/l) N (mg/l) 2 1.5 0.1 1 0.05 0.5 0 0 0 5 10 15 20 25 30 35 Salinity (ppt)

Riccardi & Solidoro (1996) showed that growth of Ulva rigida [it is now recognised that Ulva and Enteromorpha are not distinct genera] from the Lagoon of Venice was affected by the addition of phosphorus, even at very high tissue concentrations (2.65mg/g, dry weight), much higher than most critical concentrations. Lotze & Worm (2002) also observed that “the recruitment [spore germination and young shoot growth] of Enteromorpha increased exponentially with nutrient enrichment”. However, grazers such as snails and amphipods, could control algal recruitment until a nutrient threshold was reached; Lotze & Worm (2002) quoted the threshold as 100 uMol NO3 and 10 uMol PO4 L-1 (this is equivalent to 1.4mg/l N and 0.3mg/l P).

- 114 - Guidance provided by the former Department of the Environment on Eutrophication (CSTT Task Team(1997)) associated winter phosphorus concentrations greater than 6.2 µg/l with hypernutrification, based on work by Paul Tett(1975 & 1985) with limiting nutrients in phytoplankton. It is likely that macro-algal growth is limited at a similar figure during its growing season. Water quality data from the Haven at Pennar Mouth, near the discharge point, indicates that phosphorus concentrations occasionally fell below 6 µg/l prior to 2006, mainly during the summer months. The limit of detection changed to 10 µg/l in 2006, but only 4 out of 42 samples since 2006 have fallen below 10 µg/l, all of which have been in the summer. Opportunistic macro-algae will utilise available nutrients (phosphorus or nitrogen) in peak growing periods or at times of nutrient stress. Any extra phosphorus added to the water body could potentially allow more growing days in mid-summer when phosphate is likely to be most limiting. Even if water concentrations are above limiting values, plant biomass is proportional to the rate of input into the water body of the ‘most scarce’ nutrient so, if light or some other factor is not limiting, increasing concentrations of either nitrogen or phosphorus could potentially have some adverse effect. Therefore, it is possible that either nitrogen or phosphorus could limit macro-algal growth in the vicinity of the proposed discharge, including the Pembroke River estuary. Cefas were commissioned by Environment Agency Wales in 2011 to model the impact of nutrient inputs to the Milford Haven waterway and the likely effectiveness of nutrient removal scenarios in controlling macro-algal and phytoplankton growth. This study (Aldridge and Painting 2011) was carried out as part of the Agency’s investigations for the Water Framework Directive and was independent of the appropriate assessment for Pembroke Power Station. The draft and final reports were issued on 30th June 2011 and 5th September 2011 respectively. The latest report supersedes the earlier modelling studies on Milford Haven as it uses an updated version of similar software, with more recent data. Therefore, the 5th September 2011 report is considered to provide the best available information on the factors controlling macro- algal and phytoplankton growth in the Milford Haven waterway. The Aldridge and Painting (2011) report concluded that in the outer estuary, and on average the estuary as a whole, limitation by nitrogen occurred for a longer period than phosphorus limitation for both phytoplankton and macro-algae. In the inner estuary, macro-algal growth appeared to be constrained primarily by availability of habitat and, secondarily, by phosphorus limitation. However, it was recommended that the predictions of phosphorus limitation be treated with caution as observed summer average phosphorus concentrations did not support the evidence of phosphorus-limitation, possibly as a consequence of phosphorus supply from bed sediments.

5.3.3 The proposed emissions

Nutrient emissions data have been provided by RWE Npower(2011) in two ways, as follows:

ƒ Predicted average concentrations of nutrients and monthly mean flows discharging from the water treatment plant (WTP), boiler blowdown (BB) and main cooling water (CW). ƒ Proposed emission limits based on the predicted average concentrations, but allowing for natural variation of nutrient concentrations (mean +2 standard deviations) in the raw water abstracted from the Eastern Cleddau.

- 115 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The cooling water discharge does not add any additional nutrients to the estuary as those contained within it are abstracted from the Pembroke River estuary at the confluence with the Milford Haven. Therefore, this assessment concentrates on the contributions from the water treatment plant (WTP). This will result in the following loads to the Milford Haven waterway in addition to the cooling water abstraction/discharge (see Tables 5.19a & b for more details): Predicted average load:

ƒ Dissolved Inorganic Nitrogen (DIN): 6.54 kg/day; ƒ Phosphorus: 0.09 kg/day

Proposed permitted average load, suggested by the applicant:

ƒ Dissolved Inorganic Nitrogen (DIN): 9.46 kg/day; ƒ Phosphorus: 0.30 kg/day. These figures compare with the following average load estimate for all existing freshwater and point source nutrient inputs to the waterway(Mitchell 2009):

ƒ Dissolved Inorganic Nitrogen (DIN): 6590 kg/day; ƒ Dissolved Inorganic Phosphorus (DIP): 166 kg/day. Therefore, the proposed permitted average loads of dissolved inorganic nitrogen and phosphorus are equivalent to approximately 0.14% and 0.18% of the total loads of these nutrients to the Haven respectively (excluding inputs from the sea or direct aerial inputs). Nitrogen and phosphorus concentrations at the point of discharge, following dilution with abstracted cooling water, will be elevated above ambient concentrations by 0.78% and 0.35% respectively (Table 5.19b). The sole source of virtually all the nitrate (99.8%) and all of the phosphate in addition to the cooling water is from the raw water used in the WTP, which comes from the Eastern Cleddau at Canaston Bridge. There is, however, a process contribution of ammonia in the BB. Approximately 86% of the DIN load is in the form of nitrate rather than ammonia; therefore, all of the phosphate and more than 86% of the DIN will reach the river/estuary regardless of whether it is discharged by the applicant. This assessment takes a precautionary approach by assuming that all nutrients in the WTP and BB are additional loads to the Milford Haven waterway and that the power station will be discharging the proposed permitted nutrient loads, which are higher than the predicted averages.

Table 5.19a Predicted average nutrient emissions (RW = raw water, CW = cooling water, POD = Point of discharge)

WTP WTP WTP + % POD/ Substance Unit (excl Blowdown CW POD (incl RW) Blowdown ambient RW) Flow l/s 7.48 16.84 7.48 24.32 40000 40024.32 100.06 Phosphate (as P) mg/l 0 0 0.145 n/a 0.021 0.0210 100.07 Ammoniacal nitrogen (as N) mg/l 0 0.776 0.125 n/a 0.0271 0.0274 101.23 Nitrate (as N) mg/l 0.02 0 8.24 n/a 0.278 0.2794 100.49 Dissolved inorganic N mg/l 0.02 0.776 8.365 n/a 0.3051 0.3068 100.56 P load kg/d 0.00 0.00 0.09 0.0937 72.58 72.67 100.13 Ammonia-N load kg/d 0.00 1.13 0.08 1.2098 0.00 0.00 101.30 Nitrate-N load kg/d 0.01 0.00 5.33 5.3253 0.00 0.00 101.73 DIN load kg/d 0.01 1.13 5.41 6.5351 1054.43 1060.96 100.62

- 116 -

Table 5.19b Proposed permitted nutrients emissions (RW = raw water, CW = cooling water, POD = Point of discharge)

WTP WTP WTP + % POD/ Substance (excl Blowdown CW POD (incl RW) Blowdown ambient RW) Flow l/s 7.48 16.84 7.48 24.32 40000 40024.32 100.06 Phosphate (as P) mg/l 0 0 0.46 n/a 0.021 0.0211 100.35 Ammoniacal nitrogen (as N) (f) mg/l 0 0.776 0.297 n/a 0.0271 0.0275 101.35 Nitrate (as N) mg/l 0.02 0 12.13 n/a 0.278 0.2801 100.75 Dissolved inorganic N mg/l 0.02 0.776 12.887 n/a 0.3261 0.3286 100.78 P load kg/d 0.00 0.00 0.30 0.2973 93.66 94.98 101.41 Ammonia-N load kg/d 0.00 1.13 0.19 1.3210 0.00 0.00 101.70 Nitrate-N load kg/d 0.01 0.00 7.84 7.8393 0.00 0.00 101.11 DIN load kg/d 0.01 1.13 8.33 9.4576 1127.00 1136.46 100.84

5.3.4 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix: ƒ Coastal lagoons ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mudflats and sandflats ƒ Reefs ƒ Atlantic salt meadow ƒ Grey seal ƒ Anadromous fish ƒ Otter

5.3.4.1 Habitat features - the following features have been assessed together:- ƒ Coastal lagoons ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mud flats and sandflats ƒ Reefs ƒ Atlantic salt meadow

- 117 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The most likely impact on the above sensitive features would be from increased macro- algal growth, which could potentially lead to the following impacts: ƒ Smothering of eel grass (refer to section 5.6) occurring on intertidal mudflats and sandflats; ƒ Effects on benthic communities occurring within the sediment of intertidal mudflats and sandflats; and ƒ Deposition of drifting rafts of detached macro-algae on shores. Monitoring for WFD has identified sometimes dense occurrences of seasonal intertidal macro-algal blooms on intertidal mudflats and sandflats within sheltered bays and inlets in the Haven. Surveys to assess the extent of these blooms and investigations into the factors controlling macro-algal growth in the Haven are ongoing as part fulfilment of Environment Agency responsibilities under the Water Framework Directive. The classification of water bodies, as set out within the Western Wales River Basin Management Plan (December 2009), indicates that macro-algal growth is more of a problem in the Milford Haven Inner water body (currently “Moderate” status) than in the Milford Haven Outer water body (currently “Good” status). The main area of locally occurring eelgrass (Zostera noltii) is within the Pembroke River estuary (see Figure 5.16), which is at the seaward end of the Milford Haven Inner water body. It is apparent from both aerial imagery and quadrat data that macro-algae and eelgrass (Zostera noltii) co-exist in this estuary and have done so since 2009. Anecdotal fieldwork observations have not provided evidence of adverse disturbance in the form of dead eelgrass smothered by macro-algal growth, but macro-algae has been observed to be anchoring to the eelgrass in some areas. It is not clear how this will affect subsequent growth of the eelgrass in succeeding years, but this anchoring could potentially facilitate further macro-algal colonisation. With increased algal growth resulting in decreased available light and smothering of eelgrass, there is potential for dense algal mats in adjacent areas to encroach further. A review of the macro-algae data for the Pembroke River estuary has indicated that if this estuary was identified as a separate water body it would have been classified as “Good” in 2007, “High” in 2008, “Good” in 2009 and “Moderate” in 2011, suggesting an overall deterioration from 2007 to 2011. More severe deterioration was seen when biomass (weight of algae) and entrainment (algal growth through sediment) were considered on their own. Spatial growth (spread of algae) showed less deterioration. However, surveys in 2007 and 2008 were incomplete and some 2009 data were used to fill in gaps in the 2011 data. Therefore it is difficult to make full comparisons between these years. The total area of macro-algae in the Pembroke River estuary in 2011 was 42.25 hectares, compared with 26.57 hectares in 2009, suggesting an increase in the extent of macro-algal growth between these two years. In summary, macro-algal growth in the Pembroke River Estuary is less than “Good” according to WFD standards and growth appears to have increased between 2009 and 2011, although to date it appears that macro-algae and eelgrass are co-existing without obvious detrimental effects to the eelgrass. The effects of dense macro-algal growth on benthic macroinvertebrate communities are apparent from fieldwork observations in some sheltered bays (e.g. Angle Bay) and inlets (e.g. Cosheston Pill) within the Milford Haven waterway. Frequent occurrence of surface anoxia together with light limitation can have negative impacts on benthic communities, including changes in distribution and composition.

- 118 - Studies on the effects of deposition of drifting algal rafts on saltmarsh areas have been largely equivocal. It has been suggested that rafts may smother salt meadows (CCW, 2009). It is also possible that these deposits may play a role in linking water-column nitrogen supply to these habitats77, which could be beneficial in low nutrient systems. However this would probably not apply to the Milford Haven waterway. Given the current “High” status of both Haven water bodies with regard to phytoplankton and that the Haven is not an especially turbid system, it appears that a substantial build up of phytoplankton would need to occur before the sensitive features would be adversely affected. A combination of flushing and grazing would offset any accumulation of phytoplankton in the water column. In addition to the indirect effects of nutrients on sensitive features, caused by algal growth, CCW has cited references to direct toxicity of nitrate to Zostera marina and concluded that nitrate concentrations in the lower Milford Haven waterway are within a range that can result in direct toxicity to this species (Robinson, 2009). The rest of this section considers the possible impacts on the above sensitive features from the increase in nutrient concentrations at the Point of Discharge compared with ambient concentrations.

Figure 5.16 Map showing location of opportunistic macroalgae78, eelgrass79 and saltmarsh (indicative Atlantic salt meadow)80

77 See footnote 87 78 layer derived from aerial imagery from Geomatics Group, summer 2009 (as part of WFD monitoring programme) 79 layer derived from hand held GPS/ hovercraft for WFD monitoring programme, summer 2009 80 from EA Marine Monitoring Service Saltmarsh Wales indicative layer. - 119 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The average winter DIN concentrations in the receiving water bodies (Milford Haven Outer and Inner) exceed the threshold for good ecological status for the Water Framework Directive, so further increase in nitrate concentrations could potentially have an adverse effect on the sensitive features. However, the proposed permitted increase in nitrate concentrations at the point of discharge is only 0.78%, with further dilution in the receiving water, so any impact will be small. The increase in phosphate at the point of discharge is even lower at 0.35%. Wither et al.(2011) estimated concentrations of nitrogen and phosphorus in the Pembroke River Estuary (Pennar Gut) based on previous 2-D depth-averaged modelling results of a long-term tracer over a dynamic spring neap cycle reported by Acer(1995). Results of the nutrient sensitivity analysis from the Cefas dCPM model (Aldridge 2011) were then used to predict changes in macro-algal growth in the Pennar Gut resulting from the predicted increments in nutrient concentrations. Given the uncertainty about nutrient limitation, the Cefas model results for the combined inner and outer estuary (which assumes that N is the main limiting nutrient) were used for the nitrogen assessment, whereas the model results for the inner estuary alone (which assumes that P is the main limiting nutrient) were used for the phosphorus assessment. Therefore, the results can be regarded as precautionary for both nitrogen and phosphorus. It was estimated that the increase in nitrogen concentrations in the Pennar Gut area would be in the range 0.00064-0.00125 mg/l with a mean over the spring-neap cycle of 0.00087, compared with an existing annual mean of 0.345 mg/l N, equating to 0.25% of the 2008- 2010 baseline. Assuming approximate linearity, the expected increase in macro-algal growth based on the Cefas model (combined inner and outer estuary) would be considerably less than 1% (approximately 0.14% if linearity is assumed). This compares with the 19.1% natural within-year and 33% between-year variations recorded in EAW macro-algal data from Pennar Gut. It was estimated that the increase in phosphorus concentrations in the Pennar Gut area would be in the order of 1.5-3% of the 2008-2010 baseline. Assuming approximate linearity, the expected increase in macro-algal growth based on the Cefas model (inner estuary) will be expected to be a small fraction of 10% (up to 1.2% if linearity is assumed). However, the effect of adding phosphorus was reviewed based on previous emissions data, which included process contributions of phosphorus that are no longer being proposed. Given that process contributions accounted for ~93% of the phosphorus load assumed in these calculations, it can be assumed that the increases in phosphorus and macro-algal growth in the Pennar Gut will be a small fraction of 1.2%. Also, the calculations did not take into account the proposed phosphorus removal at Pembroke Dock STW, which will lead to a net reduction in the phosphorus load to Haven of approximately 1.4 tonnes/annum. Given the similar proximity of the Pembroke Dock STW and Pembroke Power Station discharges to Pennar Gut (~1.8km and ~1km respectively) there will probably also be a net reduction in the phosphorus load entering Pennar Gut from the Haven.

5.3.4.2 Species - the following features have been assessed together:- • Grey seal • Anadromous fish • Otter Increased algal growth could potentially cause indirect effects on fish through oxygen depletion or a reduction in food supply. The latter could also affect mammals. However, the slightly increased nutrient concentrations in the discharge are unlikely to result in an increase in algal growth sufficient to affect the integrity of fish or mammal populations. Therefore, it is considered that no indirect effects on fish or mammals can be expected.

- 120 - 5.3.4.3 Mitigation for potential effects

Mitigation Although the emission of N and P from the proposed environmental permit, are tiny in comparison to the overall emissions of N and P into the catchment, there is a clear Source>Pathway>Receptor connection between the emission point and the already declining eelgrass population within Pembroke River Estuary (Pennar Gut).

This reasoning and the potential risks posed were discussed with the applicant and a suitable level of mitigation proposed.

At the time of writing (10th October 2011) RWE npower proposes to enter into a contract with Dwr Cymru Welsh Water (DCWW) to reduce the input of phosphorus into the Pembrokeshire Marine SAC by the installation of phosphorus stripping equipment at Pembroke Dock Sewage Treatment Works; this will achieve an effluent concentration of 1 mg/l (BAT standard). Initial indications from DCWW are that this will reduce the annual phosphate discharge to the Haven by 1.5 tonnes. The proposed permitted phosphorus load from the power station is 0.11 tonnes per annum (average 0.032 tonnes/annum); therefore the overall result will be a net reduction in the phosphorus load to the Haven of approximately 1.4 tonnes/annum. The phosphorus stripping equipment should be installed and operational by 1st May 2012, so it should be in place prior to the summer, which is when phosphorus is most likely to be a limiting factor for algal growth.

5.3.4.4 Summary of conclusions for nutrient enrichment Evidence

The applicant is proposing to discharge nutrients from the water treatment plant (WTP), boiler blowdown (BB) and main cooling water (CW). Note - The acid cleaning operation is no longer part of this permit application with all waste products tankered off the site. We have ascertained that the applicant is employing BAT and we agree with the evidence supplied by the applicant. The proposed permitted average loads of dissolved inorganic nitrogen and phosphorus are equivalent to approximately 0.14% and 0.18% of the total loads of these nutrients to the Haven respectively. The main source of virtually all the nitrate (99.8%) and all of the phosphate in addition to the cooling water is from the raw water used in the WTP, which comes from the Eastern Cleddau at Canaston Bridge. Nitrogen (N) and phosphorus (P) concentrations at the point of discharge, following dilution with abstracted cooling water, will be elevated above ambient concentrations by 0.78% and 0.35% respectively. Previous studies have indicated that nutrient concentrations in the Milford Haven waterway are higher than those found in coastal waters around Pembrokeshire and that the waterway is hypernutrified compared to coastal standards. Studies by Cefas (Aldridge & Painting 2011) and analysis of water quality monitoring support the evidence that algal growth could be limited by either nitrogen or phosphorus in the vicinity of the power station discharge, with a possible tendency towards phosphorus limitation. Expert technical judgment

We have taken expert opinion from internal staff who are national experts upon the effects of nutrients on eelgrass beds and are aware of the latest scientific thinking. Their particular concern was the risk of dense algal mats causing smothering of inter-tidal eel grass (Zostera noltii) beds, a typical species within the Pembrokeshire Marine SAC.

- 121 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Feature conclusion Coastal lagoons, Estuaries, Large shallow inlets and bays, Mud flats and sandflats, Reefs, Grey seal, Anadromous fish and Otter

There will be a small local increase in nutrients in the water column as a result of the discharge, which will be offset by the removal of phosphate from a different source, with the net result that phosphate levels within Pennar Gut will be lower. This will lower the phosphate levels where 75% of the estuaries typical species ‘eelgrass (Zostera noltii)’ is found. This mitigation will also remove the possibility of a significant increase in anoxic conditions developing in sediments as a result of macro-algal growth and decay. It will also ensure that the dissolved oxygen levels within the water column will remain within safe limits for all life stages, as recommended by UK TAG. CCW’s condition assessment indicates that some of these features are in unfavourable: declining condition, including the estuaries feature. The net result of mitigation, will be a reduction in the quantity of biologically available phosphate, therefore it is considered that the scale of this impact, if any, will be negligible and that there may be beneficial effects. Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each sub-element of the COs. They have not been repeated in this conclusion to save space within this document. However, when considering the COs we have ascertained that, for nutrient enrichment, all of the elements of favourable conservation status will be met. Remaining doubt

Initially there was doubt about the process contributions of nutrients to the system. The applicant, as requested by the Environment Agency, undertook additional work to fully assess the likely effects of the addition of nutrients. For example:- ƒ a revised environmental emissions assessment for aqueous discharges from Pembroke Power Station (RWE Npower 2011); ƒ a report on possible effects of phosphorus, nitrogen and thermal discharges on eelgrass and macro-algal growth in Pembroke River (Wither 2011);

Equally, during the period that this appropriate assessment has been conducted additional scientific reports were received which provided the Environment Agency with new information, specifically the report by Cefas (Centre for Environment, Fisheries and Aquaculture Science) on the modelling of nutrient impacts in the Milford Haven Waterway. Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

5.3.5 Site integrity implications with respect to nutrient enrichment Overall the Environment Agency, after considering fully the conservation objectives for Pembroke Marine SAC, ascertains that there will be no adverse effect alone on site integrity. This is summarised in table 5.19.

- 122 - Table 5.19: Conclusions on site integrity, assessing the effect of nutrient enrichment in relation to the conservation objectives of special interest features Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be 3) Is the 4) Will there be 5) Will there be a 6) Will the 7) Will there be which the SAC of annex 1 changes conservation status interruption or direct effect on the natural range of indirect effects on has habitats to the of the feature degradation population of the the species the populations of been designated (or composite composition of currently of the physical, species for which within the site be species for features) the unfavourable? chemical the reduced / likely which the site be reduced, habitats for which or biological site was to be was sufficient to the site processes that designated reduced for the designated or affect the site was designated? support habitats or classified, foreseeable classified integrity? (e.g. and sufficient to affect future, sufficient due to loss or reduction in species for which the site integrity? to affect the site degradation species the site integrity? of their habitat structure, was designated (quantity/quality), abundance or or sufficient to affect diversity that classified, the site integrity? comprises the sufficient to affect habitat over time, the site integrity? sufficient to affect the site integrity?) Coastal lagoons No No No No n/a n/a n/a Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reefs No No Yes No n/a n/a n/a Atlantic salt No No Yes No n/a n/a n/a meadow Grey seal n/a n/a No No No No No Anadromous fish n/a n/a Yes No No No No Otter n/a n/a No No No No No

- 123 - 5.4 Habitat loss and Physical damage

This assessment follows the key steps shown below:

5.4.1 Effects of flow rate

The flow delivered by the pumps in normal operation will vary as a result of variations in tidal level. Automatic controls will be applied to ensure that at no time does flow exceed 40m3s-1, the maximum volume flux permitted by the abstraction licence. For low water levels, the flow will fall below 40m3s-1, to 37.8m3s-1 on mean low water springs and to a minimum of 36m3s-1at extreme low water springs. The cooling water discharge is proposed via two tunnels, each 3.96m diameter. The mean cooling water exit velocity in full operation is anticipated to be 1.6 ms-1. This velocity would reduce rapidly away from the tunnel portals, as the dredged channel (subject to permission from another competent authority and not part of this EPR permit) splays out from the tunnel portal to the relatively shallow channel across Pwllcrochan Flats. This will avoid any risk of causing significant erosion. Note: The reduction in velocity as described only occurs when the channel is confining. At higher water levels the discharged water will mix with the ambient water with resulting velocity and shear stress distributions as modelled.

5.4.2 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix:- ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mudflats and sandflats ƒ Reefs The potential risks to these habitats include erosion/scouring of soft sediments from the volume, velocity and frequency of the cooling water discharge, potential changes in sediment processes and the impact of increased temperature and biocide on the sediment (which has already been discussed in section 5.1 and 5.2).

- 124 - 5.4.2.1 Estuaries & large shallow inlets and bays

The cooling water volume is small (0.26%) compared with the natural tidal volume flow rate. Therefore, any velocity effects from the discharge flow will be expected to be localised to the discharge area and its associated channel. Modelling of the plume indicates that apart from short periods around the turn around of the tide, the cooling water discharge is deflected by the tidal cross flow on both spring and neap tides. However, even at the slack waters, the mixing of the cooling water discharge with the ambient water results in the occurrence of only small velocities (of order cm s-1). Overall the water movement is dominated by tidal flows81. Therefore it is ascertained that there will be no adverse effect alone on the estuarine habitat feature.

5.4.2.2 Mudflats and sandflats

At low tidal levels the outfall channel across the Pwllcrochan Flats will confine the cooling water discharge until the northern edge of the flats. The area in the vicinity of the outfall has been dredged to reinstate the former power stations outfall channel. The channel will then be able to accommodate the flow at a flow rate of approximately 0.65m s-1, which will significantly reduce the potential impact of erosion82. Siltation impact as a result of the scour is possible, leading to deposition and impacts on the benthic ecology. However, any impacts of scouring are likely to be very localised, whilst the dredged channel should also prevent a scouring track migrating sidewards, influenced by the tide. The channel bed material is identified from samples as consolidated sandy mud/silt of mean diameter 0.03 to 0.04 mm. The permissible velocity to prevent erosion of this material is approx. 0.6 to 1.1 ms-1. For the proposed cooling water flow these parameters are satisfied by a broad shallow channel with base width 30 m and a side slope of 1 in 6, and an effective flow depth of 1.5 metres. The mean velocity in the dredged channel at low tide, when the flow would be confined within the channel, would be approximately 0.68 ms-1 at full cooling water flow. Shear stress is directly dependent on velocity. The associated bed shear stress would be about 1.6 Pa (1 Pa = 1 Nm-2) well within the permissible shear stress for the sampled channel bed material of about 4.8 Pa. This permissible shear stress is for the relatively well- consolidated material at the sample locations in the channel bed. The equivalent value for unconsolidated silt in intertidal and shallow subtidal areas of the Haven is substantially lower. Any bare sediment formed by a scouring event is likely to be quickly recolonised by benthic organisms from neighbouring populations through migration of adults or recruitment of juveniles. The ability of the intertidal benthic communities to recover from scouring activity is high83. Although there may be some change to the mudflat in the immediate vicinity of the outfall, we believe that such effects as might arise will not adversely affect the integrity of the site, because of the small scale of any impact and the nature of the features concerned, which we believe are resilient and adaptable to a wide variety of water velocities.

81 Part II, chapter 6 - Operational Phase Physical Effects on the Haven, pg 42. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 82 Half hour resolution for a 15d period at the spring equinox compared with hourly resolution of a single tide of mean spring range and a single tide of mean neap range that was presented in CES (2007) 83 Humber European Marine Site, Habitats Directive: stage 3 Review of Consents, Water Quality Appropriate Assessment. - 125 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.4.2.3 Reefs

It is ascertained that there will be no effect on the reef habitat from the cooling water discharge due to the dissipation of the effluent momentum that will occur, preventing any physical damage or loss to this habitat. This is supported by the location of the outfall in relation to the distribution of the reef feature.

5.4.3 Summary of the potential effects of habitat loss and physical damage

Evidence

The applicant proposes to discharge the cooling water via two tunnels each 3.96m in diameter. The flow will fall below 40m3s-1, to 37.8m3s-1 on mean low water springs and to a minimum of 36m3s-1 at extreme low water springs, resulting in a fully operational exit velocity of 1.6ms-1. Expert technical judgment

We have checked the quality of any data used and the validity of assumptions. Individual feature conclusions Estuaries, Large shallow inlets and bays, Mudflats and sandflats and Reefs

The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘In the vicinity of the outfall the hydrographic processes necessary for the long-term maintenance of inlets and bays, estuaries, mudflats and reefs would no longer be determined by natural environmental processes. Although the discharge will be a change from the natural tidal movement in the vicinity of the discharge, the water column will very quickly disperse the velocity of the effluent. We are confident that the habitats which occur in the vicinity will already be resilient and adaptable to a wide variety of water velocities, from storms to flat calm weather, and as such this additional flow will not cause adverse effects. CCW’s condition assessment indicates that these features are in unfavourable conservation status. We believe the main reasons for this, from information supplied by CCW, are principally due to nutrient emission and habitat loss due to dredging. As the dredging for this proposed power station has already occurred, with permission obtained from another competent authority, we do not believe this discharge will result in additional habitat loss. As such we are confident that the potential risk will not exacerbate these causes of unfavourable conservation status nor undermine measures to return it to favourable conservation status. Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each element of favourable conservation status relating to the components of the COs. They have not been repeated in this conclusion to save space within this document. However, when considering the COs we have ascertained that:- The COs are not compromised but as some of the COs sub elements are not feasible or achievable - more aspirational, then some of the sub elements of favourable conservation status are not met. Unfortunately, the way that CCW have phrased these elements means that no project other than a remedial project, could be authorised without failing to meet the individual elements of conservation objectives.

- 126 - Sensitivity/resilience to that hazard.

Given that a channel has already been dredged (not part of this EPR permit) and that the velocity of the discharge water will reduce greatly, in the vicinity of the discharge, due to the natural velocity of the tidal waters, the proposed flow will cause no adverse effects. In conclusion, the EA has assessed the implications in view of the conservation objectives. It ascertains that there will be no adverse effect alone on the natural range and area covered, the structures and functions necessary for its long-term maintenance, and the conservation status of the typical species within these habitats. Remaining doubt

Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

5.4.4 Summary of conclusions for habitat loss and physical damage

The EA has assessed the implications for the site in view of the conservation objectives and ascertained that there will be no adverse effect on site integrity alone as a result of habitat loss and physical damage. This is summarised in table 5.20.

- 127 - Table 5.20: Conclusions on site integrity, assessing the effect of habitat loss and physical damage in relation to the conservation objectives of special interest features.

Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be 3) Is the 4) Will there be 5) Will there be a 6) Will the 7) Will there be which the SAC of annex 1 changes conservation status interruption or direct effect on the natural range of indirect effects on has habitats to the of the feature degradation population of the the species the populations of been designated (or composite composition of currently of the physical, species for which within the site be species for features) the unfavourable? chemical the reduced / likely which the site be reduced, habitats for which or biological site was to be was sufficient to the site processes that designated reduced for the designated or affect the site was designated? support habitats or classified, foreseeable classified integrity? (e.g. and sufficient to affect future, sufficient due to loss or reduction in species for which the site integrity? to affect the site degradation species the site integrity? of their habitat structure, was designated (quantity/quality), abundance or or sufficient to affect diversity that classified, the site integrity? comprises the sufficient to affect habitat over time, the site integrity? sufficient to affect the site integrity?) Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reefs No No Yes No n/a n/a n/a

- 128 - 5.5 Siltation and turbidity

This assessment follows the key steps shown below:

5.5.1 Effects of siltation and turbidity

Siltation is the physical damage caused by the deposit of suspended solids from aqueous discharges. Turbidity is a measure of the effect that suspended particles have on light attenuation in the water column. Suspended particles can be organic and inorganic and may include mud and plankton or other substances. Ultimately, turbidity determines the depth of water that light can penetrate and therefore the amount of light available for primary production by phytoplankton, benthic microalgae and macroalgae. Turbidity is very variable and transient. It depends on factors such as weather, tide and season. The effect of increased turbidity will depend on the background levels. Cole et. al. (1999) report average mean levels of turbidity of 1-100 mg/l around the English and Welsh coasts. The presence of suspended particles can come from a number of sources, for example eroded mudflats, dredging activities or sewage treatment plant discharges. The effect of increased turbidity will depend on the background levels. Suspended sediment concentration varies around the UK, from 1-327 mg/l around the English coast and 1-127 mg/l around the Welsh coast (Parr et. al., 1998, Cole et. al., 1999). Each of these references has been considered when reaching a conclusion. Most estuaries experience high levels of turbidity, especially during periods of maximum river flow. This markedly reduces the amount of light penetration with consequent implications for many photosynthetic plants (Boaden & Seed, 1985). Suspended particulate concentrations are highly variable with season, wave action, tidal conditions and freshwater discharge. As a consequence, water clarity at the seabed and water column light intensity are also highly spatially and seasonally variable. The site is very wind-exposed, but variable depending on location and topography (CCW, 2009). The proposed environmental permit will not result in the addition of any suspended solids to the cooling water, instead it will only re-circulate the natural suspended solids that are taken in from the abstraction point.

- 129 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.5.2 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix:- ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mudflats and sandflats ƒ Reefs ƒ Anadromous fish

5.5.2.1 Estuaries & large shallow inlets and bays

In estuaries, levels of turbidity are usually much higher than those of the adjacent coastal waters (Cole et. al., 1999). Increased siltation and turbidity has the potential to alter erosion and deposition processes and food availability. It also has the potential to alter the light availability for phytoplankton, benthic microalgae and macroalgae, such as eelgrass. Also at high levels, the suspended sediment that causes turbidity, may clog feeding apparatus. This effect is ‘siltation'. RWE report that total suspended solids varied from 3.9 mg l-1 (June 2009) to 195 mg l-1 (October 2006)84. This could be due to high river flows or the mixing of fresh/saltwater due to spring tides at the time of sampling, as the lower values were taken between neap and spring tides. In estuarine environments, siltation is increased by the flocculation of inorganic and organic substances due to the mixing of fresh and saltwater. Floods are likely to increase the availability of sediment entering coastal waters from rivers. Storms may also re-suspend sediment and transport it to other areas85, with suspended solids sinking very slowly and easily being re-suspended by water turbulence. The suspended sediment load in the Milford Haven waterway is relatively low compared with estuaries with less rock, although it will be spatially and seasonally variable. Turbidity is described as generally lowest towards the open coast, though it increases both widely and locally in areas affected by strong wave action, spring tides or heavy freshwater runoff86. There are prolonged periods of low turbidity, especially during spring and summer months and in areas of weak tidal current streams (CCW, 2009). Generally estuaries have low sensitivity to the effects of turbidity and siltation due to the natural turbidity that occurs. There is a suggestion that fish distribution could be linked to turbidity gradients, with some species favouring differing levels of turbidity (Cole et. al., 1999).

5.5.2.2 Mudflats and sandflats

Turbidity or suspended solids can affect benthic invertebrate communities both when the particles are in suspension and when they are deposited (Cole et. al., 1999).

84 Part II, Chapter 4 – Marine Baseline Information pg 22. Pembroke Environmental Permit Appropriate Assessment Supporting Document, 2010. 85 Web link:www.marlin.ac.uk/ 86 Whole waterway mean ≈ 24 mg l-1; mean range ≈ 10 – 55 mg l-1; lower estuary (“off Dale”) mean ≈ 10 mg l-1; off Neyland mean ≈ 16 mg l-1; upper Daugleddau mean ≈ 60 mg l-1; maximum near-bed value recorded in upper Daugleddau: ≈ 890 mg l-1 maximum near-bed value recorded in upper Daugleddau: ≈ 890 mg l-1 (CCW, 2005).

- 130 - Elevated levels of suspended solids can be beneficial to filter-feeding and suspension-feeding benthic invertebrates, as suspended solids are food resource for them. However significant elevation of suspended solids can clog fish gills and the respiratory system of benthic invertebrates. Higher turbidity (>60 mg l-1), was observed in the surface waters of the upper estuary than in the lower estuary, where mid stream concentrations rarely exceeded 10 mg l- 1. A number of factors mitigate for the potential impacts of localised increased turbidity or suspended solids on the integrity of the site, these include: ƒ Intertidal organisms in the vicinity of the cooling water discharge are likely to able to tolerate exposure to highly turbid waters; ƒ Impacts from turbidity are not permanent, and any localised impacts on the intertidal will be mitigated by seawater at high tide; ƒ It is unlikely that any of these localised impacts would result in a significant change in benthic community composition.

5.5.2.3 Reefs

The direct effect on fish populations due to turbidity could be as a result of respiratory impairment, sub lethal effects of elevated turbidity including avoidance, reduced feeding and growth, reduced tolerance to disease and toxicants, and physiological stress (Lloyd, 1987). However, moderate turbidity gradients may provide protection from predators i.e. other fish and birds (Cole et. al., 1999). The mobile species associated with the reef feature within the estuary will be able to respond rapidly to changes in the physical environment, and move to areas that are not affected. However, some reef fish species can hold territories or be limited to a range from the reef. Therefore, they will continue to occupy the habitat even when they are subjected to high levels of turbidity. However, the reef feature is distributed some 450m and beyond from the location of the outfall, and given that the impact would be localised, any impacts caused by the proposed cooling water discharge would diminish with distance. Therefore, it is considered that there would be no adverse effect alone on the reef feature or on site integrity.

5.5.2.4 Anadromous fish

Turbidity or suspended solids can directly affect fish populations, through impacts on respiration and foraging opportunity and, at extreme levels, the clogging of gill rakers and gill filaments by particulate matter. However, in some cases moderate levels of turbidity may provide some species of fish a degree of protection from predators, such as other fish and birds. Lamprey and shad are not known to occur in the vicinity of the discharge, but even if they were, should not be affected by the small localised area as they are able to respond quickly and move to areas of low turbidity.

5.5.3 Summary of the potential effects from turbidity and siltation

Evidence

The proposed environmental permit will not result in the addition of any suspended solids to the cooling water, instead it will only re-circulate the natural suspended solids that are taken in from the abstraction point.

- 131 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Expert technical judgment

We have checked the quality of any data used and the validity of assumptions. Individual feature conclusions Estuaries, Large shallow inlets and bays, Mudflats and sandflats not covered by seawater at low tide, Reefs and Anadromous fish (allis and twaite shad, sea and river lamprey).

Intertidal organisms in the vicinity of the cooling water discharge are resilient and adaptable, and as a result can easily tolerate exposure to highly turbid and silty waters. Impacts from turbidity and siltation are not permanent, and any localised impacts on the intertidal will be mitigated by seawater at high tide. We do not consider that these localised impacts would result in a significant change in benthic community composition. The concern from CCW, noted in the ‘Appendix 3 In comb matrix CCW 280610’, was that ‘The 40 m3s-1 discharge will affect the natural sediment supply (by introducing dead marine life at the discharge point) and sediment transport processes, due to the altered hydrology. Depending on the state of the tide and other variables, the water at the intake could contain considerably more silt than the receiving water’. After duly considering the concern from CCW, we believe that the levels of siltation and turbidity will remain within the wide range of natural parameters for this estuary. Predicted physical /chemical/biological effects on the ecology

Expert technical judgement from within and outside the Environment Agency has been used to consider the types of potential hazards posed by this application. We have ascertained that there would be no impact on life forms or features using local knowledge and scientific peer review. The habitats would not be significantly affected (i.e. its extent, structure and ecological functioning would not compromise conservation status, because either the effect is too far away or the predicted impact would affect too small an area to make any material difference to its character. We have also considered the ability of species to adapt behaviour, re-establish elsewhere or otherwise adapt to the changed conditions in the proximity of the hazard.

Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each sub-element of the COs. They have not been repeated in this conclusion to save space within this document. However, when considering the COs we have ascertained that:- The COs are not compromised but as some of the COs sub elements are not feasible or achievable - more aspirational, then some of the sub elements of the COs are not met. Unfortunately, the way that CCW have phrased these elements means that no project other than a remedial project, could be authorised without failing to meet the individual elements of favourable conservation status. Remaining doubt Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

5.5.4 Summary of conclusions for siltation and turbidity

- 132 -

The EA has assessed the implications for the site in view of the conservation objectives and ascertained that there will be no adverse effect on site integrity alone as a result of siltation and turbidity. This is summarised in table 5.21.

- 133 - Table 5.21: Conclusions on site integrity, assessing the effect of siltation and turbidity in relation to the conservation objectives of special interest features.

Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be 3) Is the 4) Will there be 5) Will there be a 6) Will the 7) Will there be which the SAC of annex 1 changes conservation status interruption or direct effect on the natural range of indirect effects on has habitats to the of the feature degradation population of the the species the populations of been designated (or composite composition of currently of the physical, species for which within the site be species for features) the unfavourable? chemical the reduced / likely which the site be reduced, habitats for which or biological site was to be was sufficient to the site processes that designated reduced for the designated or affect the site was designated? support habitats or classified, foreseeable classified integrity? (e.g. and sufficient to affect future, sufficient due to loss or reduction in species for which the site integrity? to affect the site degradation species the site integrity? of their habitat structure, was designated (quantity/quality), abundance or or sufficient to affect diversity that classified, the site integrity? comprises the sufficient to affect habitat over time, the site integrity? sufficient to affect the site integrity?) Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reefs No No Yes No n/a n/a n/a Anadromous fish n/a n/a Yes No No No No

- 134 -

5.6 Smothering

This assessment follows the key steps shown below:

Smothering is the physical covering of species or communities and the substratum with additional sediment (silt) or detritus. Some features are particularly sensitive to smothering, whilst others have adapted strategies to overcome smothering effects within dynamic environments such as estuaries. The source of discharged sediment, will be that entrained at the abstraction point within Pennar Gut and any local sediment re-suspended by the discharge. The source of detritus will be that from the intake waters, and as a result of the biocide, temperature and physical changes within the cooling system; resulting in the die-off of some entrained species. Typically, entrained material can also include holoplanktonic organisms (permanent members of the plankton, such as copepods, diatoms and bacteria) and meroplanktonic organisms (temporary members of the plankton, such as juvenile shrimps and the planktonic eggs and larvae of invertebrates and fish) (Bamber & Seaby, 2004). However, Bamber and Seaby (2004) exposed larval common shrimp (Crangon crangon), lobster (Homarus gammarus) and adult copepods (Acartia tonsa) to the stresses of entrainment within power station cooling water systems. They noted that the majority of individuals of each species tested would survive passage through a power-station system under normal conditions. Those species that do not survive entrainment through the cooling water system will be subsequently discharged into the estuary. It is likely that these will become a food source for other estuarine species. Smothering could also occur as a secondary effect of the increase in temperature to the estuary, combined with the effect of nutrient enrichment. The combination may potentially result in indirect effects on species and communities, for example overgrowth of algal mats, toxic effects of algal blooms or the partial smothering of eelgrass beds from suspended materials. However these risks have been fully considered in section 5.3.

5.6.2 Hazard and risk assessment

Sensitive features to be assessed following on from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix: ƒ Estuaries ƒ Large shallow inlets and bays ƒ Mudflats and sandflats ƒ Reefs ƒ Atlantic salt meadow

- 135 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 5.6.2.1 Habitats features the following features have been assessed together:- • Estuaries • Large shallow inlets and bays • Mudflats and sandflats • Reefs • Atlantic salt meadow

Estuaries can be turbid and energetic environments, having complex patterns of sediment deposition and erosion, which shape the channel and intertidal areas. These and other factors shape the response to large inputs of organic matter. In an estuary, there are many sources of organic carbon, such as decaying vegetation and phytoplankton. The amount of organic carbon produced internally can depend on the amount of nutrients present available to stimulate growth of plants and animals. Organic carbon partitions between dissolved and particulate phases. Particulate carbon moves around with sediment, hence distribution depends on particle size, particle density and currents. Both dissolved and particulate carbon are metabolised by bacteria, consuming oxygen in the process, and particulate carbon can be used by invertebrates. Ultimately, carbon is lost from rivers and estuaries through respiration87. Typically, increasing levels of organic carbon initially produces an increased number of detritivores which are a food supply for other species, resulting in a general increase in the number of species and in the overall abundance of invertebrates. Organically enriched estuaries supply greater quantities of foods for other animals including birds. However, too much organic carbon can lead to smothering and oxygen depletion both in the sediment and the water column. Numbers of species are reduced and certain tolerant species become dominant. Algal mat formation occurs in intertidal areas with high nutrient levels and with suitable substrate characteristics and tidal conditions over summer months. Algal species Ulva and Enteromorpha species are regarded as nuisance species and their cover in the intertidal area depends largely on the availability of suitable hard substratum. The presence of macro algae may predominantly affect salt marsh habitat, salicornia and other annuals and Zosteria beds. Smothering with respect to an increase in macro algae has been assessed and concluded as part of sections 5.3 nutrient enrichment.

5.6.3 Summary of the potential effects from Smothering

Evidence

The applicant is not contributing to smothering directly from any process emissions, but could indirectly potentially cause smothering, through the discharge of sediment, entrained at the abstraction point within Pennar Gut and any local sediment re-suspended by the discharge. The only source of detritus will be that from the intake waters, and as a result of the biocide, temperature and physical changes within the cooling system; resulting in the die-off of some entrained species. We have ascertained that the applicant is employing BAT and we agree with the evidence supplied by the applicant. Expert technical judgment

We have checked the quality of any data used and the validity of assumptions.

87 Humber European Marine Site, Habitats Directive: stage 3 Review of Consents, Water Quality Appropriate Assessment - 136 - Individual feature conclusions Atlantic salt meadows, Estuaries, Large shallow inlets and bays, Mudflats and sandflats not covered by seawater at low tide and Reefs.

The localised scale of any smothering effects which will predominantly be confined to the already dredged channel, the dynamic nature of the receiving environment and the dilution of the effluent plume at the location of the discharge point, will all result in minimising the effects of smothering The habitats and species concerned, are resilient and adaptable to smothering from sediment and detritus, as this is typical of the environment that they are adapted to live within. It is expected that the increased quantity of detritus will result in an initial increase in the number of detritivores which are a food supply for other species, resulting in a general increase in the number of species and in the overall abundance of invertebrates. CCW’s condition assessment indicates that some of these features are in unfavourable: declining, conservation status. We believe the main reasons for this, from information supplied by CCW, are principally due to nutrient emission and habitat loss due to dredging. The potential of smothering will not exacerbate these causes of unfavourable conservation status, nor undermine measures to return it to favourable conservation status. In principle, this is due to the nature of estuarine environments which are very resilient and adaptable, due to the wide variety of environmental factors that they experience. Conservation Objectives (COs) / Statutory considerations

All of the conservation objectives have been considered within Appendix 1’ Elements of favourable conservation status’. This includes assessing each element of favourable conservation status relating to the components of the COs. They have not been repeated in this conclusion to save space within this document. However, when considering the COs we have ascertained that:- The COs are not compromised but as some of the COs sub elements are not feasible or achievable - more aspirational, then some of the sub elements of the COs are not met. Unfortunately, the way that CCW have phrased these elements means that no project other than a remedial project, could be authorised without failing to meet the individual elements of favourable conservation status. Remaining doubt

Due to the nature of this ever changing dynamic estuary, minor scientific uncertainty does remain, however we are confident that we have taken every step necessary to minimise the level of uncertainty and that remaining minor uncertainty can be dealt with by adaptive monitoring programmes.

5.6.4 Summary of conclusions for smothering

The EA has assessed the implications for the site in view of the conservation objectives and ascertained that there will be no adverse effect on site integrity alone as a result of smothering. This is summarised in table 5.22.

- 137 - Table 5.22: Conclusions on site integrity, assessing the effect of smothering in relation to the conservation objectives of special interest features.

Site integrity effects Assessment of habitats Assessment of habitat and species Assessment of species populations populations Features for 1) Will the area 2) Will there be 3) Is the 4) Will there be 5) Will there be a 6) Will the 7) Will there be which the SAC of annex 1 changes conservation status interruption or direct effect on the natural range of indirect effects on has habitats to the of the feature degradation population of the the species the populations of been designated (or composite composition of currently of the physical, species for which within the site be species for features) the unfavourable? chemical the reduced / likely which the site be reduced, habitats for which or biological site was to be was sufficient to the site processes that designated reduced for the designated or affect the site was designated? support habitats or classified, foreseeable classified integrity? (e.g. and sufficient to affect future, sufficient due to loss or reduction in species for which the site integrity? to affect the site degradation species the site integrity? of their habitat structure, was designated (quantity/quality), abundance or or sufficient to affect diversity that classified, the site integrity? comprises the sufficient to affect habitat over time, the site integrity? sufficient to affect the site integrity?) Estuaries No No Yes No n/a n/a n/a Large shallow No No Yes No n/a n/a n/a inlets and bays Mudflats and No No Yes No n/a n/a n/a sandflats Reefs No No Yes No n/a n/a n/a Atlantic salt No No Yes No n/a n/a n/a meadow

- 138 - 5.23 Alone conclusion summary table A summary of the potential effects identified within the alone appropriate assessment, which will be carried through to the in combination assessment.

sand ck ks s als rged sea omous fish omous tal lagoons tal lagoons s Potential effects? fs

Shore Do Grey se Anadr Otters Coas Estuarie Atlantic salt meadows Large shallow inlets & bays Mud flats & flats Ree Sandban Subme cave No - 4km 0.68% (37.41ha) sea n/a 0.17% (37.41ha) 1.9% (33.08ha) 0.0006% No > No > n/a No No No away surface. sea surface. sea surface. (0.24ha) of 10km 10km 0.17% (9.08ha) sea bed. 0.04%(9.08ha) 0.36% (6.33ha) reef. away. away But only 0.26% of the sea bed. sea bed. Considered tidal volume But only 0.26% But only 0.26% of negligible Alone - Toxic of the tidal the tidal volume contamination volume n/a 9.9% (543.5ha) sea n/a 2.5% (543.5ha) 10.3% (83.1ha) 0.2% (85.2ha) n/a n/a n/a Minor No Minor surface. sea surface. sea surface. sea surface. change change 2.5% (135.4ha) sea bed. 0.6% (135.4ha) 5.6% (99.9ha) sea 0.01% (4.4ha) may occur may occu sea bed. bed. sea bed. to the to the However for 95% of the prey prey time it will be 3.9% However for 95% However – species in species i (212ha) and 1.6% of the time it will considerably the the (89ha) be 0.9% (212ha) smaller > 3deg.C localised localised and 0.4% (89ha) vicinity of vicinity o Alone - Changes in the the thermal regime discharge. discharge No net No net increase of P due n/a No net increase No net increase of No net n/a n/a n/a No No No increase of to mitigation. of P due to P due to increase of P Alone - Nutrient Phosphate due mitigation. mitigation. due to enrichment to mitigation. mitigation. Alone - Habitat loss n/a No – only 0.26% of tidal n/a No – only 0.26% No – dredging No n/a n/a n/a n/a n/a n/a and physical volume affected. of tidal volume has already damage affected. occurred. Alone - Siltation and n/a No n/a No No No n/a n/a n/a n/a No n/a turbidity Alone - Smothering n/a No No No No No n/a n/a n/a n/a n/a n/a

- 139 - 5.7 Cross comparison of potential effects on features alone

Coastal habitats sensitive to abstraction • Coastal lagoons (FCS status - Favourable maintained 2006)

As the Coastal Lagoon feature is found in four discrete locations at more than 4000m away from the emission point, any potential effect is limited. From our analysis of the potential hazards from the proposed EPR permit within section 5, the possibility of an adverse effect alone is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall.

Estuarine and intertidal habitats • Estuaries (FCS status – Un-favourable declining 2006)

The outfall from the proposed Pembroke Power Station discharges directly into the estuaries feature. Using the outputs of modelling and using marine expert knowledge, our assessment indicates that, even though this feature is currently in un-favourable conservation status, the total area of this feature exposed, after dilution, to the possibility of adverse effect (i.e. within the mixing zone) is small enough and over a short enough duration to not constitute an adverse effect on site integrity alone.

• Atlantic salt meadows (Glauco-Puccinellietalia maritimae) (FCS status – Un- favourable unclassified 2006)

Our alone assessment concludes that, even though this feature is currently in un-favourable conservation status, there will be no adverse effect on this feature as a result of the localised scale of the impacts, the dynamic nature of the receiving environment, the dilution of the effluent plume and the location of the discharge point in relation to the feature.

• Large shallow inlets and bays (FCS status – Un-favourable declining 2006)

Using the outputs of modelling and using marine expert knowledge, our assessment indicates that, even though this feature is currently in un-favourable conservation status, the total area of this feature exposed, after dilution, to the possibility of adverse effect (i.e. within the mixing zone) is small enough and over a short enough duration to not constitute an adverse effect on site integrity alone.

• Mudflats and sandflats not covered by seawater at low tide (FCS status – Un- favourable declining 2006)

Our alone assessment indicates that there will be a decrease in species richness in the immediate vicinity of the outfall. However it is not considered that this decrease would affect the functioning of the ecosystem because the impact is localised. Although the conservation status of mudflats and sandflats not covered by seawater at low tide is unfavourable-declining, the small scale of the mixing zone in comparison to the site, leads the EA to ascertain that there is no adverse effect alone.

Submerged marine habitats

• Reefs (FCS status – Un-favourable no change 2006)

- 140 - Given the very small scale of potential effect, due to the effluent plume being thermally buoyant and not contacting the reef habitat it is ascertained that there is no adverse effect from the proposed Pembroke Power Station outfall alone.

• Sandbanks which are slightly covered by seawater all the time (FCS status – Un- favourable no change 2006)

Due to the location of this feature, some 10km from the proposed Pembroke Power Station outfall, it is clear that the potential for adverse effect is limited. From our analysis of the potential hazards from the proposed EPR permit within section 5, the possibility of an adverse effect alone is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall.

• Submerged or partially submerged sea caves (FCS status - Favourable maintained 2006)

Due to the location of this feature, some 10km from the proposed Pembroke Power Station outfall, it is clear that the potential for adverse effect is limited. From our analysis of the potential hazards from the proposed EPR permit within section 5, the possibility of an adverse effect alone is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall.

Coastal plants • Shore Dock (FCS status - Favourable maintained 2006)

The appendix 11 document concluded no likely significant effect on this feature as a result of the proposed Pembroke Power Station environmental permit.

Marine mammals • Grey seals (FCS status - Favourable maintained 2006)

Grey seals are able to detect and exhibit avoidance responses to adverse conditions and are well adapted to adjust to any changes in the balance of populations within their prey species. This combined with the fact that they only spend a small amount of time in the estuary and that TRO does not tend to bioaccumulate in their food chain means that the risk of direct or indirect effects on seals from the proposed Pembroke Power Station discharge is very low. Our assessment find there to be no adverse effect alone.

Anadromous fish • Allis shad (Alosa alosa) (FCS status - Unknown 2006) • Twaite shad (Alosa falax) (FCS status - Unknown 2006) • Sea lamprey (Petromyzon marinus) (FCS status – Un-favourable declining 2006) • River lamprey (Lampetra fluviatilis) (FCS status – Un-favourable no change 2006)

The key requirement for anadromous fish in estuaries is that a passage is available at all times so that adults or juveniles that wish to migrate are not exposed to hazards that might compromise their breeding ability or the ability of the juveniles to return to the sea or in the case of river lamprey often to suitable estuarine habitat. As there will be no barriers to fish migration established as a result of discharges in the proposed PPS cooling water discharge, it is our conclusion that there will be no adverse effect alone on the anadromous fish interest features.

- 141 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Mammals of riverine habitats • Otter (Lutra lutra) (FCS status - Favourable maintained 2006)

Otter may experience a change in the balance and distribution of prey items as a result of the proposed Pembroke Power Station, which may be beneficial or adverse but, as they are able to detect and exhibit avoidance responses to adverse conditions, take a wide range of prey, including non-fish prey, and are able to switch prey if necessary, they are therefore well adapted to adjust to any such changes. On this basis, and as the area of the mixing zones associated with the proposed outfall alone is small compared with the area available to otters within both SACs, no alone effects are predicted.

- 142 - 6. In combination assessment

6.1. Overview

Under Regulation 61 of the Conservation of Habitats and Species Regulations, assessment of any plan, project or permission (PPP) likely to have a significant effect on a European site or a European offshore marine site must consider effects alone and in combination with other PPPs. This section considers in combination effects on the Pembrokeshire Marine/Sir Benfro Forol SAC and the Cleddau Rivers/Afonydd Cleddau SAC.

6.2. PPP considered ‘in combination’

Table 6.1 lists all the PPP that were initially considered for the in combination assessment for the proposed Pembroke Power Station environmental permit. This indicates distances and pathways and identifies those PPPs that were were/were not included in the in combination assessment. The list of PPP in Table 6.1 has been gathered from many sources, principally:- ƒ CCW Appendix 3 ‘In combination matrix CCW 280610’; ƒ other competent authorities; ƒ Maps 1-3 (shown in Section 6.4.1), which were compiled from the information that CCW provided to the Environment Agency. Considerably more GIS maps were used from the data provided, but only a subset has been included within this assessment, to limit the overall document size; ƒ Our own records of Habitat Risk Assessments (HRA) for existing permits which we have regulated. To ensure that the list of possible PPP to be considered in combination, was appropriate, we considered: ƒ whether the PPP was a construction or works project that is now complete – if so, the PPP will have already been considered as part of the prevailing environmental conditions (through monitoring of environmental parameters such as temperature, nutrients etc.) and effectively taken into consideration in the ‘alone’ assessment in section 5. As a result it will not be considered further in the in combination assessment to avoid double counting; ƒ whether the PPP is an ongoing permission that could potentially be revoked or changed in future – if so the PPP has been considered in the in combination assessment if a potential pathway or mechanism for in combination effects could be identified; ƒ has been excluded from consideration if no potential pathway or mechanism for in combination effects could be identified.

- 143 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Identified mechanisms for in combination effects include; ƒ zones of overlap between similar effects on an interest feature arising from different PPPs (for instance overlapping thermal plumes); ƒ zones of overlap of different types of effect arising from different PPPs (for example thermal plumes and toxic plumes overlapping to present a barrier to fish migration); ƒ the cumulative effects of different PPPs acting in different locations on the same interest feature, leading to a significant adverse effect on the interest feature in terms of the proportion of the total resource of that interest feature within the SAC that is affected.

Pathways have been identified by considering hydraulic continuity between surface waters potentially affected by the different PPPs and distances between PPPs, taking account of tidal characteristics and influences of fluvial flows.

- 144 - Table 6.1 – PPP considered and PPP included in the in combination assessment

No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

PEMBROKE POWER STATION (PPS) Pembroke Power Station Abstraction RWE EA WRA abstraction Licence issued Dec SM93650265 Water discharges Abstraction Yes HRA 2008 concluded licence (cooling water abstraction) licence 2008 (22/61/6/156) - (from Pennar Gut) are directly into the possible likely ≤40m3/s Ongoing conditional upon Intake is part of SAC in Pennar Gut 3 significant effect agreeing a fish return Pembroke Power ≤144,000m /h (LSE); AA concluded ≤3,456,000m3/d system. Station 3 no adverse effect on ≤1,200,000,000m /a integrity but to be Licence operational revisited when EPR YES Fish entrainment application finalised contributing to adverse effects on fish, in combination with PPS emission effects Pembroke Power Station RWE EA Single EPR permit for Application expected W1 - SM930032 Water discharges Earlier modelling based Yes Alone assessment in environmental permit including: PPS (across are directly into the on: progress. DP3333TA Pwllcrochan Flats) SAC - flow = 38m3/s Ongoing Conclusions not yet aerial emissions; (= 3,283,200 m3/d) available W2 - SM937023 - ΔT = 8.1K cooling water discharge (to Pennar Gut) Draft application data including commissioning (W1); and AA info available All part of water treatment plant effluent Pembroke Power 2009 modelling is based including commissioning (W1); Station on: 3 boiler blowdown (W1); - flow = 40m /s (= 3,456,000 m3/d) acid clean (commissioning - ΔT = 7.6K phase) (W1) (no longer part of this - TRO = 50µg/l YES permit application with all waste

products tankered off the site) (Primary Main concerns: PPP) uncontaminated surface water (W2). - thermal load - TRO - also emissions of inorganic nitrogen and phosphates The 2009 modelling is definitive for thermal effects. Updated TRO undertaken in January 2011 Pembroke Power Station site runoff RWE EA EPR permit for water Issued W3 - SM937023 Water discharges Discharge of up to Yes HRA Appendix 11 (basement void) (W3) discharge activity (to Pennar Gut) are directly into the 24000m3/d of shallow form available – EA (outside PPS environmental permit Associated with SAC in Pennar Gut groundwater, saline due to Ongoing concludes no LSE YES boundary) PPS environmental intrusion. Contaminants alone or in permit meet EQS. combination Pembroke Power Station temporary Alstom EA EPR permit for water Permit issued Jan 2010 SM937023 Water discharges Oxygen demand Yes HRA Appendix 11 sewage discharge (construction and (may be discharge activity to Dec 2012 - (to Pennar Gut) are directly into the form available – EA commissioning) transferred to NPSWQD008613 will be ongoing Associated with SAC in Pennar Gut Nutrients Temporary at present but concluded no LSE may become permanent (likely to be retained and permit RWE) PPS environmental Microbiological alone or in varied to reduce volume) permit. contamination combination, CCW disagrees re nutrients YES EA still to revisit this if the discharge becomes permanent (albeit smaller)

- 145 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Pembroke Power Station ro-ro jetty Alstom EA Land drainage consent SM937023 Within SAC, within Direct effects on habitat No, as complete Environmental refurbishment (Pennar Gut) Milford Haven statement WG Marine licence ** Associated with Sediment plumes Temporary NO MHPA Marine works licence Licence issued 2009 PPS environmental Mobilisation of MWL.06.09 permit contaminants Complete Pembroke Power station dredging of RWE WG Marine licence ** and Licence issued, expired SM930033 and Within SAC within Direct effects on habitat No, as complete MHPA AA dated intake and outfall channels and ro-ro variation 33270/10/0 Jan 2011 SM942026 Milford Haven 30/10/09 jetty approach (Pwllcrochan Flats Sediment plumes Temporary MHPA Marine works dredging Dredging licence issued and Pennar Gut) Mobilisation of NO licence and variation 2009 Associated with MWL.03.09 contaminants Complete 2010 PPS environmental permit Pembroke Power station dredge RWE WG Marine licence ** Complete 2010 Two sites Outside SAC Direct effects on habitat No (outside Haven at N/A disposal SR772855 and great distance and SR493931 approx Sediment plumes sediment effects will be 30km and 47km local to disposal ground) Mobilisation of NO from PPS outfall via contaminants main axis of Milford Temporary Haven and out to sea Pembroke Power Station gas pipe RWE PCC Planning permission Complete From AGI at Vertically below No – all work was land- No, as all land-based N/A sub-sea directional drilling SM926059, via SAC based and water MHW on north discharges fully controlled N/A bank at SM915052 so no mechanism for to MHW on south marine effects. bank at SM924032 NO to AGI at PPS at SM927027 Associated with PPS environmental permit Pembroke Power Station Temporary Alstom WG Marine licence ** Licence issued, expired SM937026 Within SAC within Direct effects on habitat No, as complete N/A – part of baseline coffer dam 34489/09/0 May 2010 Associated with Milford Haven Temporary PPS environmental NO MHPA Marine works licence Licence issued 2009 permit MWL.04.09 Complete EA ONGOING PERMISSIONS South Hook LNG South Hook EA EPR permit for Ongoing W1 - SM874054 Within SAC within W2 discharge Yes HRA Appendix 11 LNG Terminal installation W2 – SM872045 Milford Haven - flow ≤1000m3/d, form available – EA site run-off (W1) Co XP3538LD - T ≤30°C Ongoing concludes no LSE W2 is 6.5km west - nitrates ≤75mg/l as NO - alone or in YES submerged combustion from PPS outfall via 3 vaporisers discharge (W2) - TRO ≤100µg/l combination (joint main axis of Milford assessment with Haven Dragon LNG) South Hook LNG South Hook EA EPR permit for water Ongoing SM874053 Within SAC within Discharge Yes HRA Appendix 11 LNG Terminal discharge activity Milford Haven - SS ≤75mg/l available for revised site drainage treated with PAC Co BG0042401 6.8km west from - oil and grease ≤15mg/l Ongoing consent to include YES PPS outfall via - aluminium ≤0.5mg/ PAC – EA concluded main axis of Milford - pH 6-9 no LSE alone or in Haven combination

- 146 - No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Murco Refinery discharges Murco EA EPR permit for Ongoing W1 - SM886046 – Within SAC within W1 discharge Yes AA completed 2007, installation 718m offshore Milford Haven - flow ≤25000m3/d, concluded no adverse process water (W1) EP3838LG - T ≤27°C Ongoing effect on integrity. W1 is 5km west - ammonia ≤16mg/l emergency discharge to Sandy (Numbers in RoC were from PPS outfall via Included in Review of Haven (W2) - COD ≤200mg/l BY5269 (was AF7886)) main axis of Milford - also limits on pH, oil, Consents but to St Botolphs Stream (W3) Haven phenols, sulphides, outcome reported in YES fluorides, cyanides, SS, AA report above. groundwater to Rickeston Water Cu, Ni, Fe, Zn (W4) W2 – SM863070?? Note: numbering different in Appendix W3 – 11 form dated July 2007 W4 – SM880092?? Chevron Refinery discharges Chevron EA EPR permit for Ongoing SM907042 Within SAC within W1 discharge Yes AA completed 2007, installation Milford Haven - flow ≤25000m3/d, concluded no adverse process water (W1) QP3033LW (as varied) W1 is 2.5km west - T ≤35°C Ongoing effect on integrity. of PPS outfall in a - ammonia ≤20mg/l Pwllcrochan Weir surface water (Numbers in RoC were straight line Included in Review of overflow to Martin’s Haven (W2) - COD ≤270mg/l YES BZ2150 (was AF7984) - also limits on pH, oil, Consents but outcome reported in West Reservoir emergency phenols, sulphides, overflow to Angle Bay (W3) fluorides, cyanides, SS, AA report above. Cu, Ni, Fe, Zn Dragon LNG terminal and storage Dragon LNG EA EPR permit for Ongoing Aqueous effluent is N/A N/A considered as part of N/A HRA Appendix 11 installation all directed via Semilogistics form available – EA HP3238LJ Semlogistics’ concludes no LSE was AP3136UA (as effluent TP alone or in NO varied) combination (joint assessment with South Hook LNG) Semlogistics Waterston (formerly Semlogistics EA EPR permit for Ongoing C - SM941041 Within SAC within C discharge Yes No, not included in Petroplus) tank storage discharges installation (approx 200m Milford Haven - flow ≤10000m3/d, Review of Consents BK1341IN from shore) - T ≤30°C Ongoing surface water, ballast and - ammonia ≤5mg/l as N effluent TP discharges via east catch (Numbers in RoC were D – SM929055 - BOD ≤50mg/l basin (C) AF7860 and BB9962) (enters Milford - SS ≤70mg/l Haven at - also limits on pH, oil, surface water from tank farm SM919050) and railway area via west catch basin TOC, formaldehyde, YES (D) E – SM940053 methanol (enters Milford site drainage via north catch Haven at basin (E) SM948048) C is 1.3km north east of PPS outfall in a straight line Existing surface water abstraction Various EA WRA abstraction Ongoing Check revealed no Only consider No as there are no No pathway – refineries RoC concluded no licences, regulated by the EA (not inc. licence abstraction licences abstractions within licensed c/w abstractions get water from Dwr alone or in PPS abstraction licence) direct from Milford Milford Haven for refineries, where fish Cymru/Welsh Water combination effects NO Haven entrainment would have been a consideration Existing discharge permits regulated DC-WW EA EPR permits for water Ongoing Various Discharging to Oxygen demand Yes Review of Consents by the EA – sewage works (mainly) discharge activity rivers draining to Milford Haven or Nutrients Ongoing No alone or in YES direct to the SAC combination effects within Milford Haven

- 147 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Existing discharge permits regulated Various EA EPR permits for water Ongoing Various Only consider Oxygen demand Pathway present but no RoC – see by the EA – other than sewage works discharge activity within Milford significant non-sewage spreadsheet Haven Nutrients works discharges ‘TMW05_06 Toxic contamination identified, so no potential Appendix 2’ for in combination effects NO No alone or in Ongoing combination effects

MAINLY LAND-BASED PLANNING DEVELOPMENT Miscellaneous. land based Various PPC/PCN Planning Ongoing Various Only consider Suspendeded solids, Pathway present but no developments with environmental PA within Milford smothering significant discharges pathway to impact onto SAC. Haven catchment identified, so no potential N/a (especially during construction) with environmental Nutrients for in combination effects NO pathway to SAC Toxic contamination Ongoing during construction only Retaining wall – Blackbridge Pill Presceli EA Land drainage consent SM915060 Outside SAC in Indirect effects on habitat No, as complete N/a Construction 3.8km north west Blackbridge Pill PCC Planning permission from PPS outfall via Construction site run-off No due to very limited pathway WG Marine licence ** main axis of Milford NO $ Haven and into Temporary MHPA Marine works licence Licence issued 2008 Blackbridge Pill RWL.02.08 Complete (Castle Pill) Fort Road car park revetment PCC EA Land drainage consent SM955036 Within SAC within Direct effects on habitat No, as complete N/a 2.5km inland from Milford Haven PCC Planning permission PPS outfall in a Construction site run-off Temporary WG Marine licence ** straight line NO MHPA Marine works licence $ Licence issued 2008 RWL.03.08 Complete Brunel Quay seawall PCC EA Land drainage consent SM967050 Within SAC within Direct effects on habitat No, as complete N/a 5.1km inland from Milford Haven PCC Planning permission PPS outfall via Construction site run-off Temporary WG Marine licence ** main axis of Milford NO $ Haven and into MHPA Marine works licence Licence issued 2008 Westfield Pill RWL.04.08 Complete Carew Causeway repairs PCNPA EA Land drainage consent SN041038 Within SAC within No No, as complete N/a 14.3km inland from Milford Haven, at PCC Planning permission PPS outfall via head of long No, due to distance and nature of works WG Marine licence ** main axis of Milford tributary NO Haven and into Temporary MHPA Marine works licence Licence issued 2009 Carew River MWL.01.09 Complete Retaining wall – Blackbridge Pill S&D Property EA Land drainage consent SM915060 Outside SAC in Indirect effects on habitat No, as complete N/a Development 3.8km north west Blackbridge Pill Ltd PCC Planning permission from PPS outfall via Construction site run-off No, due to very limited pathway WG Marine licence ** Application submitted main axis of Milford 10/30 Haven and into Temporary MHPA NO $ Blackbridge Pill Marine works licence Application submitted (Castle Pill) Complete (same location as no. 19)

- 148 - No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Martello Quays (marina, leisure & Martello Quays PCC Outline planning OPP approved 2009 SM967038 Outside SAC at Indirect effects on habitat Yes No HRA identified but housing development) Ltd permission (OPP) Planned start 2012 Approx 4.6km Pembroke Dock but environmental inland from PPS close to SAC Construction site run-off Temporary statement available WG Marine licence ** No application yet outfall via main axis boundary plus CCW letters re YES MHPA Marine works licence No application yet of Milford Haven at HRA. Pembroke Dock MHPA Marine works dredging No application yet licence Burton Marina Pembroke PCC Planning permission Early discussions, no SM982047 Within SAC within Direct effects on habitat Unknown as not enough N/a Marine Group definite plans yet and Approx 6km inland Milford Haven detail available. MMO Marine licence ** no notification of or from PPS outfall via Construction site run-off NO MHPA Marine works licence applications to main axis of Milford competent authorities Haven at NATO Jetty, Burton Point Shoreline Management Plan EA Strategic plan SMP1 Pre-dates The coastline of Includes Potential effects on Yes Only a draft HRA implementation of Wales, Pembrokeshire habitat, but only a draft available Ongoing – but only draft at Habitats Regulations. Marine SAC plan at the moment. NO present SMP2 – draft form only

MARINE WORKS AND ACTIVITIES (CAPITAL/ONE-OFF) South Hook LNG berth capital South Hook WG Marine licence ** Completed 2006 SM873044 Within SAC within Direct effects on habitat No, as complete N/A dredging LNG Terminal 6.5km west from Milford Haven Co. MHPA Marine works dredging PPS outfall via Temporary NO licence main axis of Milford Haven South Hook LNG Jetty construction South Hook WG Marine licence ** Completed 2009 SM873044 Within SAC within Direct effects on habitat No, as complete N/a LNG Terminal 6.5km west from Milford Haven Co. MHPA Marine works licence PPS outfall via Temporary NO main axis of Milford Haven South Hook LNG Jetty refurbishment South Hook EA Land drainage consent Complete SM873044 Within SAC within Direct effects on habitat No, as complete N/a LNG Terminal 6.5km west from Milford Haven Co. WG Marine licence ** PPS outfall via Temporary NO MHPA Marine works licence main axis of Milford Haven Dragon LNG Jetty works Dragon LNG WG Marine licence ** Completed 2007 SM927044 Within SAC within Direct effects on habitat No, as complete N/a 1.1km NNW from Milford Haven MHPA Marine works dredging Temporary PPS outfall in a NO licence straight line, on north bank

Dragon LNG channel widening and Dragon LNG WG Marine licence ** Completed 2008 SM925023 Within SAC within Direct effects on habitat No, as complete N/a berth – capital dredging 1.1km NNW from Milford Haven MHPA Marine works dredging Licence not used for PPS outfall in a Temporary NO licence channel widening – straight line, on ploughed instead north bank Semlogistics berth 3 capital dredge Semlogistics WG Marine licence ** Completed 2009 SM931042 Within SAC within Direct effects on habitat No, as complete N/a 1.1km north from Milford Haven MHPA Marine works dredging PPS outfall in a Temporary NO licence straight line, on north bank

- 149 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Capital dredge disposal (South Hook Various WG Marine licence ** Completed Two sites Outside Milford Direct effects on habitat No, as complete N/a LNG, Dragon LNG, SemLogistics SR772855 and Haven, outside berth 3) SR493931 approx SAC Temporary 30km and 47km NO from PPS outfall via main axis of Milford Haven and out to sea Fisheries pontoon - Milford Docks South and MHPA Marine works licence $ Licence issued 2008 SM902055 Within SAC within Direct effects on habitat No, as complete N/a West Wales RWL.01.08 3.9km west from Milford Haven Sea Fisheries Complete PPS outfall via Temporary NO Committee main axis of Milford Haven MHPA Tug Berth pontoon, Carr Jetty MHPA MHPA Marine works licence $ Licence issued 2008 SM957041 Within SAC within Direct effects on habitat No, as complete N/a RWL.05.08 2.8km inland from Milford Haven NO Complete PPS outfall in a Temporary straight line MHPA South Yard Walls and Dolphin MHPA WG Marine licence ** SM958040 Outside SAC at Indirect effects on habitat No, as complete N/a repairs Approx 3.6km Pembroke Dock but Construction site run-off MHPA Marine works licence Licence issued 2009 inland from PPS close to SAC Temporary MWL.02.09 NO Complete outfall via main axis boundary of Milford Haven at Pembroke Dock Deployment of telemetry buoy and CCW WG Marine licence ** Application submitted SM744095 Within SAC, No, effect will be de No, too far outside Haven N/a oceanographic sonde - Skomer 10/08 26km from PPS outside Milford minimis outfall via main axis Haven Temporary NO of Milford Haven and out to sea Mid Channel Rocks marker - renewal MHPA WG Exempt Exempt SM810015 Within SAC, No, effect will be de No HRA screening and 13km from PPS outside Milford minimis AA undertaken and MHPA Marine works licence Licence issued in 2010. outfall via main axis Haven Temporary concluded no adverse NO MWL.01.10 Is exempt but MHPA of Milford Haven in effect on the integrity maintains ‘paper trail’ Milford Haven of the SAC alone or in entrance combination. Turbot Bank ODAS Buoy Trinity House WG Marine licence ** Deployed 2009 SR827946 Within SAC, No, effect will be de No, as complete N/a 18.5km from PPS outside Milford minimis outfall via main axis Haven No, too far outside Haven NO of Milford Haven Temporary and out to sea Blackbridge new jetty and offshore MHPA PCC Planning permission Early discussions, no SM915050 Within SAC within Direct effects on habitat Yes MPHA master plan energy base probably definite plans yet and 2.3km north west Milford Haven and hydrography still under MMO Marine licence ** no notification of or from PPS outfall in Permanent preparation, status NO MHPA Marine works licence applications to a straight line not yet defined. No competent authorities further information yet available. Moorings CCW map available MHPA MHPA Marine works licence No new moorings Moorings are Within SAC within Direct effects on habitat No, as complete N/a proposed (MHPA present throughout Milford Haven only when and after new 24/2/11) Milford Haven moorings installed (de Temporary minimis). Existing permissions – NO works complete Note CCW moorings map includes anchorages – not relevant MARINE WORKS AND ACTIVITIES (MAINTENANCE/ONGOING)

- 150 - No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Maintenance dredging 2006 MHPA WG Marine licence ** Complete Various Within SAC within Direct effects on habitat No, as complete N/a Milford Haven MHPA Marine works dredging Temporary NO licence Maintenance dredging 2010 MHPA WG Marine licence ** On-going for 5 years Various Within SAC within Direct effects on habitat Yes AA completed on 4th Milford Haven Oct 2010. MHPA Marine works dredging Temporary YES licence MWL.02.10 Semlogistics and Dragon LNG Semlogistics WG Marine licence ** Completed 2008 SM930042 Within SAC within Direct effects on habitat No, as complete N/a maintenance dredging and Dragon 1.1km north from Milford Haven LNG MHPA Marine works dredging PPS outfall in a Temporary NO licence straight line, on north bank Maintenance dredging disposal MHPA WG Marine licence ** Application submitted Two sites Outside Milford Direct effects on habitat No N/a SR772855 and Haven, outside SR493931 approx SAC Temporary 30km and 47km NO from PPS outfall via main axis of Milford Haven and out to sea Neyland Marina trickle dredge and Neyland Yacht WG Marine licence ** Last licence expired Jan SM968047 Dredging outside Indirect and direct effects Yes AA completed by disposal Haven 34595/10/0 2011 5.5km inland from SAC in Westfield on habitat WAG, concluded no MHPA PPS outfall via Pill, disposal within Temporary but annual adverse effect on YES No involvement of Ongoing – annual main axis of Milford SAC within Milford integrity. MHPA except issuing applications Haven and into Haven notice to Mariners Westfield Pill Recreational activities (vessels) N/A MHPA No specific permission Ongoing Designated water Within SAC within Noise effects only, as No, if only noise Only info available is but water skiing, sail ski areas off Dale Milford Haven wash in confined areas is considered what is contained in boarding, aquaplaning, SAC Management Plan Anchorage, Angle, regulated. We are not the SAC para-kiting prohibited by identifies high-speed Milford and including noise from PPS Ongoing Management Plan MHPA General power craft, non- between Cleddau in the assessment so no (allocated F4/F7) Directions 2006 mechanical power craft Bridge and Carew need to consider. (Direction 27) and by and vehicles as F7 but River confluence. MHPA Byelaw 29 accepts they are not a outside allocated areas. PPP PWC aquabatics only allowed off F7 (activity having a significant adverse effect) Pwllcrochan Flats. NO through noise and wash Dead slow/ effects from high speed minimum wake craft in sheltered waters zones in Dale Bay, Sandy Haven Pill, Angle Bay, Pembroke River, Cosheston Pill and inland of Carew River confluence

FISHING

Mussel settlement trials Thomas Vivian MHPA Marine works licence Licence issued 2009 - Entrance to Angle Within SAC within Direct effects on habitat No, if complete HRA Screening and Ltd MWL.05.09 Bay centred on Milford Haven through dredging AA undertaken and Tackle & cultivating SM885036 Temporary concluded no adverse YES lines in place. Turbidity effect on the integrity consider Harvesting not yet 5.5km west of PPS of the SAC alone or in together commenced. discharge via main combination. axis of Milford Haven

- 151 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Angle Shellfish Several Order Colin Thomas WG Fish Order under s.1 of Sea Order applied for. Entrance to Angle Within SAC within Direct effects on habitat AA by Cefas, January Fisheries (Shellfish) Act Bay centred on Milford Haven through dredging 2009, concludes no SM885036 effect on integrity Turbidity alone but possible 5.5km west of PPS effects in combination discharge via main axis of Milford Haven Angle Shellfish dredging (C. Colin Thomas SWSFC Authorisation under Authorisation issued Entrance to Angle Within SAC within Direct effects on habitat No, if complete Apparently no HRA fornicata) (now WG Byelaw 2 31 March 2010 Bay centred on Milford Haven carried out Fish) SM883035 Temporary 5.5km west of PPS NO discharge via main axis of Milford Haven Cockling Various MHPA Fishery regulated by N/A Angle Bay only at Within SAC within N/A N/A Covered by MHPA WAG (ex SWSFC) present Milford Haven Fisheries Byelaws byelaws but no specific NO permits for cockling by hand Oyster dredging N/A WG Fish Fishery regulated by Dredging currently None Within SAC within Maerl removal Potentially Covered by MHPA WAG (ex SWSFC) limited under Milford Milford Haven Fisheries Byelaws byelaws but no specific Haven Port Authority Ongoing NO permits for fishing fisheries bylaws. seaward of Cleddau Bridge Scallop dredging (residual impacts) N/A WG Fish No specific permission, Banned under Scallop None N/A Removal of benthic No, as complete No, as banned now a ban is in place Fishing (Wales) (No.2) habitat, which includes but NO Order S.I. 2010:269 is not limited to maerl Permanent (W.33) Bait digging (commercial is main N/A WG Fish No specific permission On-going Dale Flats Within SAC Boulder turning and Potentially Bait digging not concern) SM812066 manual digging believed regulated so no SAC Management Plan to be having an adverse Ongoing formal HRA. argues that this activity Sandy Haven Pill effect on the SAC constitutes a plan or SM857081 although for manual Only info available is project under the digging the assessment in what is contained in Habitats Regulations. Angle Bay the SAC SM895024 the SAC Management However the activity is Plan seems confused Management Plan. not regulated, so Gelliswick Bay indicating F1 (plan or To discuss with SAC argument questionable SM886056 project), F4 (mechanism Officer (Sue Burton NO Milford Haven but insufficient evidence to 01646 696108) SM905057 determine effect), F5 (mechanism but no effect) Pembroke Dock and F7 (activity having a SM955036 significant adverse effect). Pembroke River SM961021 Lawrenny SN018062 Recreational activities (angling) N/A WG Fish No specific permission No specific permission Throughout Milford Within SAC within Effects on fish but de Yes Only info available is Haven Milford Haven minimis what is contained in EA Ongoing Ongoing the SAC NO SAC Man Plan identifies Management Plan angling as F4/F7 but (allocated F4/F7) accepts it is not a PPP RENEWABLE ENERGY

- 152 - No. PPP Applicant Comp. Consent type Status (e.g. applied NGR - emission Location Mechanism for in Pathway for in HRA info available In-comb – authority for/complete) or activity relative to SAC combination effect? combination effect? included?

Location Duration of effect relative to PPS

Deployment of 1.2MW DeltaStream Tidal Energy WG Marine licence ** Application submitted Approx SM713251 Within SAC, Direct effects on habitat Yes EIA scoping report tidal energy demonstrator device Ltd 10/28 Approx 43km from outside Milford via device footprint and and NTS of the ES. - Ramsey Sound DECC PPS outfall via Haven via effects on hydrography Permanent and ongoing No Habitats NO main axis of Milford – expect effects very Regulations Haven and out to localised Assessment available sea to consider. Deployment of Rotech tidal energy EON Lunar WG Marine licence ** No application yet Approx SM710235 Within SAC, Direct effects on habitat Yes No device Energy Approx 42km from outside Milford via effects on hydrography - Ramsey Sound DECC PPS outfall via Haven Permanent NO main axis of Milford Haven and out to sea Deployment of 10MW wave energy Marine Energy WG Marine licence ** No application yet Approx SM870990 Within SAC, Direct effects on habitat Yes No demonstrator device Ltd Approx 18km from outside Milford via effects on wave - off Castlemartin coast DECC PPS outfall via Haven exposure Permanent NO main axis of Milford Haven and out to sea Deployment of Swan Turbines tidal Swan Turbines WG Marine licence ** No application yet Not known Not known Direct effects on habitat Yes No energy device. via effects on hydrography NO DECC Permanent Deployment of 10MW wave energy Wave Dragon WG Marine licence ** No application yet Approx SM790050 Within SAC, Direct effects on habitat Yes No demonstrator device Wales Ltd Approx 20km from outside Milford via effects on wave – west of Marloes Peninsula, NW of DECC PPS outfall via Haven exposure Permanent NO St Ann’s Head main axis of Milford Haven and out to sea

- 153 -

The resultant PPP included in this permission

Table 6.2 shows the PPPs that have remained within this in combination assessment, based on the criteria in section 6.2.

Table 6.2 – Types of permission relating to PPPs included in the assessment Plan, project or permission (PPP) Type of PPP Permission Reference

Pembroke Power Station (PPS) environmental Ongoing Environmental permit application DP3333TA permit (principle permit for this assessment) (W1 permission and W2)

Pembroke Power Station abstraction Ongoing Abstraction licence issued 22/61/6/156 permission

Pembroke Power Station surface run-off – basement Ongoing Environmental permit issued HP3820XU void permission

Pembroke Power Station Sewage Discharge Ongoing Environmental permit granted WQD008613 permission (temporary)

South Hook LNG (W1 and W2) Ongoing Environmental permit (installation) XP3538LD permission granted

South Hook LNG site run-off Ongoing Environmental permit (water discharge BG0042401 permission activity) granted

Murco Refinery (W1, W2, W3 and W4) Ongoing Environmental permit (installation) EP3838LG permission granted

Chevron Refinery (W1, W2 and W3) Ongoing Environmental permit (installation) QP3033LW permission granted

SemLogistics Waterston (C, D and E) Ongoing Environmental permit granted BK1341IN permission

Other sewage works discharges Ongoing Environmental permit (water discharge Various permission activity) granted

Martello Quays Project Outline planning permission issued

Maintenance dredging 2010 5 year Marine licence from MHPA MWL.02.10 permission Marine works dredging licence MWL.02.10 from WG

Neyland Marina trickle dredge and disposal Annual project WAG marine licence issued/application

Mussel settlement trials Project Marine works licence issued MWL.05.09

Angle Shellfish Several Order Project Statutory Order application

6.3. Receiving water characteristics

In order to fully understand the relationship of PPPs with the proposed Pembroke Power Station (PPS) environmental permit, analysis of water flows from within Milford Haven waterway, were considered. This has allowed us to consider any overlapping effects. The tidal regime in Milford Haven is well described by reference to tidal diamonds on Admiralty Charts 3474 and 3465. Figures 6.1 to 6.7 show tidal excursions for these points, represented graphically, moving from Burton Ferry in the east to the mouth of Milford Haven in the west. Figure 6.8 shows the locations of the tidal measuring points.

- 154 - Figures 6.1 to 6.7 – Tidal ellipses (springspring tides) in Milford Haven

Spring tide ellipse 3274C Spring tide ellipse 3274D M ilford Haven Entrance Stack Rock 6 6

4 4

2 2

0 0 km north km north km -2 -2

-4 -4

-6 -6 -5 -3 -1 1 3 5 7 9 11 13 15 -5 -3 -1 1 3 5 7 9 11 13 15 km east km east

Spring tide ellipse 3274E Spring tide ellipse 3275A South Hook LNG Chevron Jetty 6 6

4 4 2 2

0 0 km north km -2 north km -2

-4 -4 -6 -6 -5 -3 -1 1 3 5 7 9 11 13 15 -5 -3 -1 1 3 5 7 9 11 13 15 km east km east

Spring tide ellipse 3275B Spring tide ellipse 3275C P ennar M outh Neyland Spit 6 4

4 2

2 0

0 -2 km north km north -2 -4

-4 -6

-6 -8 -3-11357911131517 -11 3 5 7 9 1113151719 km east km east

Spring tide ellipse 3275D Burton Ferry 4

2

0

-2

km north km -4

-6

-8 -12 -10 -8 -6 -4 -2 0 2 4 6 8 km east

- 155 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Figure 6.8 – Admiralty tidal measuring stations in Milford Haven

Neyland Spit Chevron Stack Burton Rock South Pennar Ferry Entrance Hook Mouth LNG

Using data from these tidal measuring stations, the main tidal characteristics of the Haven are: ƒ Burton Ferry – spring tide excursion flows 8km inland on flood, 20km seaward on the ebb (showing dominance of fluvial flow at low water); ƒ balanced flood and ebb excursions from Pennar Mouth to entrance, with spring tide excursions varying from 15km at Pennar Mouth to 10-12km in the area from Chevron Jetty to South Hook LNG Jetty and declining to 4km at the mouth of the Haven; ƒ tidal eddies occur around Dockyard Bank, giving a complex ebb pattern for the monitoring point at Neyland Spit. The extent and orientation of these spring tidal ellipses provides an indication of the maximum extent and direction of an effluent plume or of mobilised sediment in a single tide. The distance from the PPS outfall to the mouth of Milford Haven is about 10 km (via the main channel), thus any material or thermal load discharged will not reach the mouth within one tidal cycle. Effects on non-mobile habitats and species of the SAC outside Milford Haven are only likely to occur if the effects of the plume are accumulated over a number of tide cycles. If this were to occur mixed bulk water movement leaving the Haven on the ebb tide could potentially affect habitats and species in the open sea. This is realistically only a possibility for effects of nutrient enrichment.

- 156 - 6.4. Overview by type of effect

The Environmental Permit for the proposed Pembroke Power Station (PPS) environmental permit, if issued, will regulate emissions to air and water, as well as vibration and noise. Emissions to air have already been assessed as having no likely significant effect in the 'Appendix 11 EPR final revised Apr 11' report (EA/EPR/DP3333TA/A001, revised 7 April 2011). However, even though these are very minor contribution of nutrients to the Haven catchment, they have been considered as part of the nutrient enrichment and listed in Table 6.12. Noise and vibration will be associated only with construction and operation of the power station itself and there will be no emission of noise or vibration directly to the Pembrokeshire Marine/Sir Benfro Forol SAC. Marine construction associated with the PPS is now complete, so there will be no noise emissions to the SAC from that source. Deliveries by ship are part of the normal activity of the harbour and are not individually regulated thus cannot realistically be included in the assessment. Therefore, noise is not included in this in combination assessment. Terrestrial construction elements of the power station development have been considered. However, in an e-mail from RWE (21st March 2011), the construction works are at an advanced stage across the project, with construction completion having occurred in a number of areas. This in combination assessment therefore focuses principally on the emission of water from the PPS, involving 2 discharges, one of uncontaminated water (W2) and a single contaminated discharge which will comprise: ƒ direct cooling water discharge (including during commissioning); ƒ effluent from the site water treatment (including during commissioning); ƒ effluent from boiler blow through or steam purge; ƒ effluent from the boiler blowdown. Note: Acid cleaning is no longer part of this permit application with all waste products tankered off the site Hazards arising from the PPS emissions to water have been identified in the features list at the beginning of this document, which identifies the SAC interest features that are at risk from each of these hazards. Table 6.3 identifies (by turquoise cells) which of these hazards could arise from each of the PPPs taken into account in the in combination assessment.

- 157 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

6.4.1 Maps of different PPPs

Map 1 – Detailed map of the different activities around the proposed PPS.

Map 2 – Larger scale map of the different activities around the proposed PPS.

- 158 -

Map 3 – Consideration of the discharges, abstractions and landfills around Milford Haven waterway.

- 159 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

Table 6.3 – Hazards associated with PPPs included in the in combination assessment

(Note: Yellow – indicates the Pembroke Power Station environmental permit; Blue indicates the key hazards in relation to each PPP)

Plan, project or permission (PPP) Toxic contamination contamination Toxic Changes to thermal regime Nutrient enrichment* Habitat loss or physical damage to interest features and turbidity Siltation Smothering Pembroke Power Station (PPS) environmental TRO plus (5) (4) permit other contaminants (1)

Pembroke Power Station abstraction

Pembroke Power Station surface run-off – (1) basement void

Pembroke Power Station Sewage Discharge

South Hook LNG (W1 and W2) TRO (4) (4)

South Hook LNG site run-off Aluminium

Murco Refinery (W1, W2, W3 and W4) Ammonia, (4) (4) phenol

Chevron Refinery (W1, W2 and W3) Ammonia, (4) (4) phenol, metals

SemLogistics Waterston (C, D and E) (4) (4)

Other sewage works discharges (4) (4)

Martello Quays (2)

Maintenance dredging 2010

Neyland Marina trickle dredge and disposal (3)

Mussel settlement trials

Angle Shelfish Several Order

(1) – contaminants meet marine EQS (2) - note marina development is outside SAC boundary (3) – note dredging is outside SAC boundary (but disposal is within boundary) (4) – potential indirect effects of eutrophication (5) – includes potential indirect effects of eutrophication

- 160 - 6.5. Toxic contamination

6.5.1. Sources of the hazard

The principle sources of ecotoxicological effects arising from the proposed PPS are: ƒ total residual oxidants (chlorination by-products or TRO) arising from chlorination of abstracted cooling water to control biofouling at 50µg/l; ƒ other potentially toxic contaminants, including ammonia, may arise from commissioning and maintenance process but it has been established that, due to dilution with cooling water, these will be present at concentrations of less than the EQS values on entry via the main discharge (W1) to Milford Haven. Please note that chlorination by-products and their effects on typical species have been considered in Section 5.1.5.2. In addition to the biocide, the final discharge will contain a number of other substances. However, as discussed in the revised 'Appendix 11 EPR final revised Apr 11', these meet the relevant EQS at the point of discharge. Following consultation on our draft the Applicant submitted further revised versions of the document entitled ‘Environmental Emissions Assessment for aqueous discharges from Pembroke Power Station ENV/476/2011’ in October 2011 (Issue 4). It accounts for the following changes:

ƒ New blow-down rates based on experience at Staythorpe Power Station (an operational sister site); ƒ Revised raw water concentrations; ƒ Revised information from their water treatment plant supplier; ƒ Substitution of the polyphosphonate WTP antiscalant with a (non-phosphate bearing) polycarboxylate compound; ƒ Substitution of the trisodium phosphate HRSG treatment chemical with the (non- phosphate bearing) sodium hydroxide; and ƒ The W1 discharge will no longer include the pre-operational chemical clean as the Applicant has decided to remove this effluent from the site by tanker rather than discharge it to the Milford Haven waterway.

The result of their raw material substitutions is that they will no longer add any phosphate to that which is already present in the raw water treated by the WTP. The point of discharge concentrations of the various substances in the W1 discharge are considered by the Applicant in their screening report i.e. the total of the contributions made by the WTP effluent, HRSG blow-down and background provided by the cooling water. These include ammonia, unionised ammonia, iron, aluminium, arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc for which there exists an Environmental Quality Standard (EQS) as well as pH, total suspended solids, chloride, sulphate, silicate, sodium & potassium, calcium, magnesium, alkalinity, antimony, manganese, selenium, nitrate and phosphate for which there is no EQS. Nutrients are considered separately in this appropriate assessment in sections 5.3 and 6.7.

- 161 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 In the final version of the report only one assessment has been carried out using mean WTP substance concentrations and the predicted mid-range concentrations of substances in the HRSG blow-down, as opposed to the previous short- and long-term assessments using maximum and mean values respectively. It should be noted that at least some of the contribution of substances to the final W1 discharge results from the removal of substances from the raw water in the WTP in the preparation of demineralised water for the HRSGs. This raw water is sourced from the Eastern Cleddau at Canaston Bridge upstream of the Milford Haven Waterway and would therefore be present in the river/estuary regardless of its utilisation by the power station. Raw water contribution aside, the only process contributions made by the proposed power station arise from the use of a number of raw materials in the WTP and the HRSGs. These give rise to the contributions set out in Table 6.3a below:

Table 6.3a Process contributions to W1 discharge

(adapted from Table 1 of ENV/476/2011: Environmental Emissions Assessment for aqueous discharges from Pembroke Power Station: Issue 4: October 2011) Cooling WTP (ex. raw WTP (inc. raw HRSG blow- Substance Units water (i.e. water contribution) water contribution) down ambient) Ammoniacal mg/l 0 0.1250 0.7760 0.0271 nitrogen (as N) Unionised ammoniacal nitrogen mg/l 0 0.0051 0.0315 0.0011 (as N) Chloride mg/l 7.7400 75.300 0 18218 Phosphate mg/l 0 0.1450 0 0.0210 Sulphate mg/l 306.11 343.28 0 2641.0 Nitrate (as N) mg/l 0.02 8.24 0 0.2780 Silicate mg/l 0 0 3.0000 2.0000 Sodium & Potassium mg/l 344.27 385.21 3.0000 11148 Iron mg/l 0.006 0.64 5.5000 0.0001 Calcium mg/l 0.0001 50.090 0 306.40 Magnesium mg/l 0 13.020 0 1290.0 Aluminium µg/l 7375.0 8321.1 0.0082 0.4000 Antimony µg/l 0.2111 2.8500 0 0.2000 Arsenic µg/l 0.7144 3.7000 0 9.7000 Cadmium µg/l 0.5042 0.7000 0 0.0312 Chromium µg/l 1.1121 3.2600 0 2.0000 Copper µg/l 0.5620 9.7900 0 3.9500 Lead µg/l 18.113 25.830 0 0.59700 Manganese µg/l 0.1183 42.240 0 0.4000 Mercury µg/l 0.0195 0.1200 0.0005 0.0193 Nickel µg/l 0.5674 5.1100 0.0033 5.7900 Selenium µg/l 0.5359 3.2700 0 1.0000 Zinc µg/l 0.1137 22.750 0 14.890 pH - - 7.0000 9.3000 7.9950 Suspended solids mg/l - 13.370 5.5000 12.220 Alkalinity mg/l - 189.11 0 90.150

The process contributions in Table 6.3a above give rise to point of discharge concentrations as set out in Table 6.3b on the following page. Concentrations are displayed both in absolute terms and relative to ambient and each EQS.

- 162 -

Table 6.3b. Point of discharge concentrations for W1 discharge (adapted from Table 1 of ENV/476/2011: Environmental Emissions Assessment for aqueous discharges from Pembroke Power Station: Issue 4: October 2011) Point of discharge Point of discharge Point of concentration as concentration as Substance Units discharge EQS (AA) percentage of percentage of concentration EQS ambient Ammoniacal 101.23 mg/l 0.02743 1.1 2.4 nitrogen (as N) Unionised 101.23 ammoniacal mg/l 0.00111 0.021 5.3 nitrogen (as N) Chloride mg/l 18206 - 99.94 Phosphate mg/l 0.02101 - 100.07 Sulphate mg/l 2639.4 - 99.94 Nitrate (as N) mg/l 0.27937 - 100.49 Silicate mg/l 2.0000 - 100.00 Sodium & 99.94 mg/l 11141 - Potassium Iron mg/l 0.00249 1 0.25 4524.85 Calcium mg/l 306.22 - 99.94 Magnesium mg/l 1289.2 - 99.94 Aluminium µg/l 1.9548 1000 0.2 488.71 Antimony µg/l 0.20041 - 100.21 Arsenic µg/l 9.6948 25 38.78 99.95 Cadmium µg/l 0.03135 0.2 15.68 100.36 Chromium µg/l 1.9993 0.6 99.97 Copper µg/l 3.9494 5 78.99 99.99 Lead µg/l 0.60146 7.2 8.35 100.75 Manganese µg/l 0.40765 - 101.91 Mercury µg/l 0.01932 0.05 38.64 100.06 Nickel µg/l 5.7874 20 28.94 99.96 Selenium µg/l 1.0000 - 100.00 Zinc µg/l 14.885 40 37.21 99.97 pH - 7.9944 - 99.99 Suspended 99.98 mg/l 12.217 - solids Alkalinity mg/l 90.130 - 99.98

As can be seen from Tables 6.3a and 6.3b, for those substances for which an EQS is defined the contribution made by the power station is very small when compared to existing ambient seawater concentrations (i.e. background levels in the cooling water) and the point of discharge concentrations are below the relevant EQS. The point of discharge concentration of iron is higher than the ambient concentration (indicative seawater concentration rather than Milford Haven-specific) and the largest iron load arises from the HRSG blow-down, with most of the remainder deriving from the raw water. However, despite this, the point of discharge concentration is only 0.25% the EQS. Similarly for aluminium, the point of discharge concentration is higher than ambient. In the case of aluminium this arises primarily from the addition of poly-aluminium chloride coagulant to the WTP process. The point of discharge concentration is nevertheless only 0.2% of the EQS. In light of the above discussion regarding the contributions of various substances we do not consider that detailed modelling is required and further, we consider that there will be no likely significant effect on the Pembrokeshire Marine SAC and no significant pollution will arise. We therefore consider that the emissions will be acceptable. Ammonia is considered separately below.

- 163 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The indicative EQSs for total ammonia in saline waters are 8 mg/l as a MAC and 1.1 mg/l as an Annual Average. The proposed total ammonia concentration at the point of discharge is 2.49% of the Annual Average EQS. On this basis we are satisfied that modelling of total ammonia is not required. We are confident that there will be no likely significant effect on the Pembrokeshire Marine SAC arising from total ammonia and there will be no significant pollution. Ammonia is most toxic in its unionised state, particularly for fish, and an EQS of 0.021 mg/l as an Annual Average has been considered by the Applicant in the screening assessment. The Applicant’s proposed point of discharge concentration for unionised ammonia is 5.3% of the EQS. This is based on simple dilution by the cooling water and does not fully account for the effect of temperature, salinity and pH in the cooling water on ammonia within the water treatment plant and HRSG blow-down effluents. Therefore, as a precautionary measure, we have recalculated the unionised concentrations for the point of discharge based on average pH and salinity and an assumption that temperature could reach 30ºC. When the unionised ammonia concentration is recalculated on this basis it rises only marginally to 5.6% of the EQS. We are therefore satisfied that detailed modelling of unionised ammonia is not required and there will be no likely significant effect or significant pollution (though it should be noted that ammonia is considered in the context of nutrient enrichment quite separately in Section 5.2.2 and our conclusions in that respect are set out in that section). In the case of substances and other measures of effluent quality (such as alkalinity) for which an EQS does not exist, the point of discharge concentrations/values are below ambient seawater concentrations with the exception of nitrate, antimony and manganese. For these substances, although the point of discharge concentration is above the ambient seawater concentration this is almost entirely due to the raw water contribution (99.8% in the case of nitrate, 92.6% in the case of antimony and 99.7% in the case of manganese). In almost all cases the point of discharge concentrations/values are between 99% and 101% of the ambient concentrations/values. The point of discharge concentrations of these contaminants are therefore essentially the same as in the incoming cooling water and we are satisfied that such levels are below that which could potentially result in their concentration in sediments or biota, or be detrimental to the long-term maintenance of the species populations of the features of the Pembrokeshire Marine SAC. The point of discharge concentration of manganese is slightly higher at just under 102% of the ambient concentration. However, only a very small amount of manganese is added to the process by the Applicant (as a trace constituent of the WTP raw materials), with the greatest proportion being present in the raw water which would have been present in the Milford Haven regardless of whether it were discharged by the proposed power station or not. We are satisfied that in the case of all substances/values not subject to an EQS the degree of increase afforded by the proposed power station is not sufficient to give rise to a significant effect on the Pembrokeshire Marine SAC or any significant pollution. We have also considered the various substances discussed above in the context of the additional load that they provide to the Milford Haven Waterway at the point of discharge and their potential impacts, which are shown in Table 6.3c below.

- 164 - Table 6.3c: Contaminant loads arising from W1 discharge

Additional loads from environmental permit discharges Pollution Inventory Significant loads excluding raw water contribution Metal reporting triggers (kg/year) (kg/year to 3 significant figures) (kg/year) [based on proposed permit conditions] Aluminium N/A N/A 1740 [1740] Antimony N/A N/A 0.0498 Arsenic 5 20 0.169 Cadmium 1 5 0.119 Calcium N/A N/A 0 Chloride N/A N/A 1830 Chromium 20 N/A 0.262 Copper 20 N/A 0.133 Iron 1000 N/A 2922 Lead 20 N/A 4.27 Magnesium N/A N/A 0 Manganese N/A N/A 0.0279 Mercury 0.1 0.5 0.00487 [0.00991] Nickel 20 N/A 0.136 [0.665] Selenium N/A N/A 0.126 Silicate N/A N/A 1590 Sodium & N/A N/A 6620 Potassium Sulphate N/A N/A 72208 Zinc 100 N/A 0.0268

As can be seen from the table above, none of the loads are considered significant either for Pollution Inventory reporting purposes or for permitting purposes under the Dangerous Substances Directive and so we do not consider that these loads are likely to give rise to a significant effect or significant pollution. The only exception is iron which is almost three times the reporting threshold. However, iron is a geologically common metal which occurs naturally in sediments at relatively high concentrations compared to most other metals and so in common with the other substances we do not consider the load for iron to pose a risk of giving rise to a significant effect or significant pollution. As a result of discussions with the Applicant following comments received in relation to the consultation on our draft decision, they now propose to replace the phosphorus-based antiscalant they initially intended to use in the WTP to a polycarboxylate compound (comprising polyacrylic acid homopolymers (CAS 9003-01-4) and poly-(acrylic/maleic) acid copolymers (CAS 52255-49-9)). The Human and Environmental Risk Assessment (HERA) undertaken by the Applicant has derived a Predicted No Effect Concentration (PNEC) of 1.2 mg/l for acrylic acid polycarboxylates in freshwater. The corresponding PNEC for saltwater is 0.12mg/l (a more stringent assessment factor is applied because there are no marine toxicity data). Based on the HERA assessment, acrylic acid polycarboxylates are not readily biodegradable. The predicted concentration of the antiscalant at the point of discharge is 0.003 mg/l. This is well below the PNEC and so we consider that it will have no adverse effect on site integrity, nor will it give rise to significant pollution.

- 165 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 On 27 July 2011, Countryside Council for Wales (CCW) raised concerns that existing levels of toxic contaminants within the sediments of the Haven are already at levels which are causing an adverse effect on site integrity. In particular, in further information provided on 30 September 2011, they have cited copper, lead, mercury, zinc and hydrocarbons as being problematic. Canadian sediment quality guidelines have been adopted in the UK as the basis for assessing sediment quality. These consist of a Threshold Effect Level (TEL) and a Probable Effect Level (PEL). These guidelines were developed further in Quebec to provide an Occasional Effect Level (OEL). The TEL is the lower level and represents the concentration below which sediment associated chemicals are not considered to represent significant hazards to aquatic organisms. The PEL is the upper level and represents the lower limit of the range of chemical concentrations that have been associated with adverse biological effects. The sediment guidelines are not standards and are intended to be used as triggers for further investigation. Definitive standards have not been set because of the complicating factors surrounding bioavailability and toxicity of chemical in sediments. Where sediment chemistry data sits between the TEL and PEL and where there is no evidence of biological impact, no adverse effect can be concluded. Sediment data collected from a sub-tidal site at Cosheston Point (within the Milford Haven waterway) to meet the requirements of the Clean Seas Environment Monitoring Programme (CSEMP) has been assessed against these thresholds. The data covers the period from 2000 to 2011. Cadmium is below the TEL, mercury is at the TEL and zinc is between the TEL and the OEL (but nearer the TEL). Arsenic, lead and chromium concentrations are between the TEL and OEL. Copper is between the TEL and PEL and very variable between years. Our Water Framework Directive (WFD) benthic assessment tool looks at the quality of the animal communities living in sediments and can be considered a measure of current biological impact. Classification of the inner Milford Haven based on 2011 data shows it to be firmly within ‘Good’ ecological status, with the statistical risk of the water body being at less than ‘Good’ ecological status being <20%. The sites classified as ‘Moderate’ ecological status do not indicate that any particular area of the water body are subject to any considerable pressure. The classification at most sites are based on single samples and the distribution of ‘Moderate’ sites appears consistent with a normal degree of natural variability within a typical transitional water body. WFD classification of the outer Milford Haven is also firmly within ‘Good’ ecological status and from the WFD surveillance data, the statistical risk of the water body being at less than ‘Good’ ecological status is <1%. We conclude on the basis of this sediment quality and benthic community data that there is no existing adverse effect and given that point of discharge concentrations of substances in the W1 discharge are below EQS we consider there to be no risk of an adverse effect arising from the discharge in respect of sediment quality and the quality of benthic communities. The CSEMP data also includes information on Polycyclic Aromatic Hydrocarbons (PAHs). It shows reasonably consistent results until 2007, after which the results vary considerably, with two large peaks in 2008 and 2011. The replicate samples taken in these years vary by up to two orders of magnitude. Anthracene, benzo(a)anthracene, benzo(a)pyrene, chrysene, fluoranthene and pyrene are between the TEL and OEL until 2007. Phenanthrene is at the OEL until 2007. Naphthalene is between the TEL and PEL until 2011. No contributions of organics are made by the W1 discharge other than Chlorinated By-Products (CBPs). These arise as a result of interactions between residual oxidants in the cooling water associated with its chlorination and the hydrocarbons already present in the Milford Haven waterway. Such interactions are considered in Section 5.2.3.1 of this decision document. While the information upon which we have based our Likely significant effect assessment (Stage 2): Appendix 11 EPR final revised Apr 11 (dated 07 April 2011) has been updated since its submission to CCW, we remain satisfied that none of the above substances/measures of effluent quality will give rise to any likely significant effect on the Pembrokeshire Marine SAC either alone or in combination with other plans, permissions or projects.

- 166 - Other PPPs that may potentially give rise to toxic contaminants are: ƒ potentially toxic contaminants may be present in the discharge of surface run-off via dewatering of the former power station basement void but it has been established that any toxic contaminants will be present at concentrations of less than the EQS values (as shown below) on entry to Milford Haven thus can exert no likely significant effect (LSE) (see 'Appendix 11 EPR final revised Apr 11' report – EA/EPR/HP3820XU 26th January 2011); ƒ total residual oxidants (chlorination by-products or TRO) arising from use of chlorination at South Hook LNG terminal, where an emission limit of 100µg/l of TRO is set in the environmental permit (BW9816/XP3535ME (SHLNG) and BT7817/HP3238LJ (DLNG) 13th July 2007), which covers permit variations for the LNG facilities; ƒ polyaluminium chloride (Aquatreat 600 flocculant, used to ensure compliance with 75mg/l suspended solids emission limit) from South Hook LNG site run-off; however, the Likely significant effect assessment (Stage 2) - report BG0042401, dated 3rd March 2009 identified no LSE from aluminium toxicity with the emission limit set at 1mg/l; this limit has since been reduced to 0.5mg/l and is below the Environment Agency’s EAL; ƒ sodium hypochlorite is used as a biocide at both the Milford Haven and Pembroke refineries in cooling towers to prevent legionella. The doses are small and given the treatment afforded by their effluent treatment system reduces TRO levels to below the limit of detection at the point of discharge into the Haven Waterway. The chlorinated by- products were considered below as toxic contaminants. ƒ toxic contaminants in discharge W1 from the Milford Haven (Murco) Refinery; the Stage 3 Appropriate Assessment report 1st August 2007 (under the former operation by Total) reported on the assessment undertaken as part of the re-permitting; potential effects of toxic contaminants on marine SAC interest features were examined for substances where the process contribution was shown using the H1 methodology to exceed 1% of the environmental assessment level (EAL), namely ammonia and phenol; ƒ toxic contaminants in discharge W1 from the Pembroke (Chevron) Refinery; the Stage 3 Appropriate Assessment report 1st August 2007 reported on the assessment undertaken as part of the re-permitting; potential effects of toxic contaminants on marine SAC interest features were examined for substances where the process contribution was shown using the H1 methodology to exceed 1% of the EAL, namely ammonia, copper, cyanide, iron, phenol and zinc; toxic contaminants in discharge C from the SemLogistics Waterston site, which include the same parameters mentioned for Pembroke Refinery above but at significantly lower loadings; no previous Habitats Regulations Assessment has been identified.

6.5.2. Mechanisms for in combination effects In combination effects relating to toxic contaminants can arise through: ƒ toxic effects in the water column on mobile interest features or on juvenile stages of typical species of non-mobile interest features, due to plume overlap creating EQS exceedances or due to exposure of migratory fish to multiple pressures, if they migrate through a number of mixing zones on route through Milford Haven; ƒ spatially separate local toxic effects on non-mobile interest features which in combination add up to a sufficient effect on that interest feature to represent an adverse effect on site integrity.

- 167 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 6.5.2.1 Total residual oxidants (TRO)

The proposed sodium hypochlorite dosing regime and the characteristics and fate of TRO entering Milford Haven in the PPS cooling water discharge have been discussed in detail in section 5.1. Results of dispersion modelling of TRO discharges from the proposed PPS presented in Figures 5.2 and 5.3 show the mixing zone (where the EQS of 10µg/l as a 95 percentile will be exceeded, taking data across a complete equinoctal spring-neap tide cycle), for a base case (expected) decay rate and a more precautionary decay rate. As expected, bearing in mind that the cooling water will be buoyant in the receiving environment due to its elevated temperature, the zone of exceedance at the bed is much smaller than at the sea surface. Taking the base case decay rate (as described in section 5.1.4), the most westerly (seaward) extent of the mixing zone boundary (for 10µg/l 95 percentile) is: ƒ at the sea surface: 730m, to a point just east of Pwllcrochan Stream (Martin’s Haven); ƒ at the sea bed: 150m, to a point off the shore at Pwllcrochan Flats. The only other identified TRO discharge is from South Hook LNG facility. Loadings compared with those of the proposed PPS discharge (when chlorination is in operation) are estimated in Table 6.4, based on permitted values in the effluent.

Table 6.4 – TRO loads relating to PPPs included in the assessment

Plan, project or permission (PPP) TRO concentration Maximum flow TRO loading limit rate

Pembroke Power Station (PPS) 50µg/l 3456000m3/d 173kg/d* environmental permit

South Hook LNG (W2) 100µg/l 1000m3/d 0.1kg/d Note that this figure does not take into account the period of time (3 months) when sodium hypochlorite will not be used by the power station.

The extent of the mixing zone at South Hook is expected to be around three orders of magnitude smaller than at PPS (in proportion to the loadings), and the slightly smaller tidal excursion and deeper water over the outfall at South Hook compared with Pennar Mouth would be expected to make the area of the South Hook mixing zone even smaller by comparison. The South Hook discharge is 6.5km west of the proposed PPS outfall, so it is clear that the two mixing zones will not overlap and will be separated by nearly 6km. Thus there is no significant likelihood that the plumes could combine to produce areas, additional to those arising from each discharge alone, where the EQS would be exceeded. The extent of the PPS discharge mixing zone out from the shore over the equinoctal spring neap tide cycle is estimated as 730m at the sea surface, leaving a gap to the north shore, with an even greater gap below the sea surface. The South Hook discharge is about 900m from the north shore and 1000m from the south shore. The plume is likely only to be a few metres wide as it rises to the surface, so no significant part of the width of the Haven will be occupied by the mixing zone at this point. As TRO is discharged in buoyant effluents in both cases, exposure of the sea bed itself will be very limited (see 5.1.4). The area of the PPS discharge mixing zone is estimated as 21ha at the sea surface and 5ha at the sea bed. The corresponding areas associated with the South Hook discharge are both likely to be less than one hectare

- 168 - 6.5.2.2 Other toxic contaminants

Chlorination by-products and their effects on typical species have also been considered in Section 5.1.5.2. For some PPPs (PPS discharge from W188, PPS basement void discharge and South Hook LNG surface waters) other toxic contaminants identified are predicted to be present at concentrations below the EQS at the point of discharge and thus can be determined not to contribute to any effects on the interest features which could affect integrity, when added to effects of other hazards or other discharges on the same interest feature. In the case of the refineries (i.e. Murco and Chevron), the same conclusion is expected to be applicable to the SemLogistics discharge, in each case use of dilution factors from the H1 methodology and current limits in the environmental permits result in process contributions that are well below the EAL/EQS values. For the refineries, the alone assessment in each case concluded that there would be no adverse effect on integrity. These other toxins could potentially have an additive in combination effect with TRO from PPS in the water column. Although detailed modelling is not available, the refinery discharges and the SemLogistics discharge can all be ascertained to achieve a significant initial dilution, as all three discharge through pipes that are submerged at all times. All are warm discharges and will therefore be buoyant. All three have flow rates which are more than two orders of magnitude less than the proposed PPS discharge flow rates and discharge into a zone of the Haven with a similar tidal regime. Thus, even with dilutions of up to 400 times being required at the mixing zone boundary to reach the EQS for some parameters, taking account of the fairly linear tidal excursions (Figures 6.3, 6.4 and 6.5) in the vicinity of the relevant discharges, it is clear that the mixing zones will not extend to the vicinity of the proposed PPS outfall (where there is no mixing zone except for TRO). Thus there is no potential for the contribution from the PPS discharge, although below the EQS, to cause a change in the size of the mixing zones for the refineries or SemLogistics discharges. Thus there is predicted to be no in combination effect with the proposed PPS discharge, for toxic contaminants other than TRO (although see also section 6.6.3). Concentrations of some toxins (e.g. non-ionised ammonia) are affected by the thermal regime. This is dealt with under section 6.6.3. As discussed earlier, metals can accumulate in sediment, however, metals in the proposed PPS discharge will leave the discharge point at concentrations below the EQS, so the PPS discharge can be discounted as a likely source of significant accumulation in sediments, thus no in combination effects will occur. Further information supporting this is included within section 5.1. In the presence of ammonia, the predominant product of the initial rapid reactions of hypochlorite with ammonia and bromide ions is dibromamine. The degradation half life for dibromamine can range between 30 minutes to 3 days depending on pH, temperature and relative ammonia concentrations (Lewis et al., 1994). With the exception of the bromophenols and chlorotoluenes all of the chlorination by- products degrade in a couple of days or less (See Table 6.5). As part of the assessment of chlorination by-products in the appropriate assessment the dibromophenols were not considered significant because studies had found them to be undetectable in cooling water effluents. Tribromophenol and the chlorotoluenes were assessed for their potential to bioaccumulate in the food chain. Further consideration in this section of in combination effects of toxic contaminants has therefore focussed only on TRO.

88 Environmental Emissions Assessment for aqueous discharges from Pembroke Power Station ENV/476/2011 October 2011 (Issue 4) - 169 - Table 6.5 Chlorination by-products

Chemical Fate and Behaviour Chloroform Adsorbs to suspended solids and sediment. Principle degradation route for the aquatic environment is volatilisation. Measured volatilisation half life in a river of 1.2 days and estimated half life ranging from 3.5 hours to 4.4 days. It is unlikely hydrolyse or readily biodegrade but can undergo anaerobic degradation by sulphate reducing bacteria. The potential for bioconcentration in aquatic organisms is low. Bromoform Naturally produced by macroalgae such as Ascophyllum nodosum and Fucoid species. Adsorbs to suspended solids and sediment. The main degradation route for the aquatic environment is volatilisation with an estimated half life of 7.3 hours in rivers but it is also reported in Taylor 2006 that half life can be up to 26 hours. It is subject to anaerobic degradation in acclimated sediments with 99% degradation in 2.5 days. Hydrolysis is not an important degradation route. The potential for bioconcentration in aquatic organisms is low.

Dichlorobromomethane Adsorbs to suspended solids and sediment. Principle degradation route for the aquatic environment is volatilisation with an estimated half life of 4 hours to 5 days. Taylor reports a half life of 9 hours. It isn't likely to degrade readily by either hydrolysis of biodegradation. The potential for bioconcentration is low.

Dibromochloromethane Unlikely to adsorb to suspended solids or sediment. Volatilisation is the principle degradation route with an estimated half-life of 2.6 hours to 6 days. Taylor reports a half life of 17 hours. It can be anaerobically degraded in 2-8 weeks. It has a low potential for bioconcentration.

Dibromoacetic acid It is unlikely to adsorb to suspended solids or sediment. Does biodegrade but not readily. It has a low potential for bioconcentration.

Dibromoacetonitrile Dibromoacetonitrile is highly soluble, is not expected to sorb to sediments or suspended solids, and is not expected to volatilise from water surfaces. However, it is expected to undergo rapid hydrolysis in the aquatic environment, with an estimated hydrolytic half-life of 2 days. Taylor reports a half life of 14 hours. Dibromoacetonitrile is not expected to bioaccumulate in aquatic organisms. 2,4 -dichlorophenol Adsorbs to suspended solids and sediment. Photolysis is the primary degradation route with a half life of 0.6 to 3 hours in estuarine water and rapid biodegradation of breakdown products. It may also volatilise with an estimated half life of 14 to 103 days. It has a low to moderate potential for bioconcentration.

2,4,6-trichlorophenol Adsorbs to suspended solids and sediment. Photolysis is the primary degradation route with a half life of 2.1 hours. It may also volatilise with a half life of 20-150 days. It will be subject to some biodegradation and test indicate a half life of 6.3 days. It has a high potential for bioconcentration. 2,4-dibromophenol Adsorbs to suspended solids and sediment. Anaerobic degradation in marine sediments under test conditions had a half of 5 days. Volatilisation is unlikely. The potential for bioconcentration is low.

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6.5.3. Potential in combination effects from other hazards

The principle concern regarding toxic contaminants interacting with other hazards is the fact that ionisation of ammonia is temperature dependent so, as non-ionised ammonia concentrations increase with temperature and non-ionised ammonia is the toxic fraction, warming caused by thermal discharges can increase toxicity. This is dealt with under section 6.6.3. In addition, any potential effects of toxic contaminants on migratory fish could act in combination with effects on fish populations of impingement and entrainment of fish through abstraction of cooling water. An increase in temperature can increase the toxicity of TRO to aquatic organisms. There is limited information on the significance of this effect and it varies between species and temperature range. From the data available the effect appears to be most significant between about 15 and 30oC. In Lewis et al. (1994) it is reported that toxicity increases by a factor of 2 between 10 and 30oC. Temperature was not a specific consideration in the derivation of the current EQS but the toxicity data assessed to derive the standard was taken from tests conducted at a range of temperatures (10 to 22oC) (Lewis et al, 1994). Sorokin et al. noted that temperature has less effect on chlorine toxicity than other physicochemical parameters such as pH but there are insufficient high quality data for temperature –chlorine interaction effects in aquatic taxa to set temperature dependent PNECs for chlorine. An increase in temperature will also increase the rate of reaction of hypochlorite and the subsequent degradation of any chlorination by-products.

6.5.4. In combination effects on interest features 6.5.4.1 Overview

Referring back to the sensitive interest features (hazard and risk assessment), shown in Table 1, Table 6.6 identifies which interest features could be affected by each of the PPPs where toxic contamination is a potential hazard arising from the permission, based on information from the ‘alone’ assessments where available. Cells are colour coded according to the results of each ‘alone’ assessment – green = no Likely Significant Effect from Stage 2 assessment 'Appendix 11 EPR final revised Apr 11'); yellow = no adverse effect on integrity from the Appropriate Assessment; orange = not determined; grey = no hazard identified from the 'Appendix 11 EPR final revised Apr 11' risk matrix.

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Table 6.6 – Interest features potentially affected by toxic contamination from PPPs included in the assessment

Plan, project or permission (PPP) -tidal r Coastal lagoons lagoons Coastal Estuaries inlets Large shallow & bays & sandflats Mudflats inte Reefs Atlantic salt meadows slightly Sandbanks covered Sea caves Grey seal Anadromous fish spp) (4 Otter Pembroke Power Station (PPS) environmental permit

Pembroke Power Station surface run- off – basement void

South Hook LNG (W2)

South Hook LNG site run-off

Murco Refinery (W1)

Chevron Refinery (W1)

SemLogistics Waterston (C) (Note: Cells are colour coded according to the results of each ‘alone’ and in combination assessment – green = no LSE; yellow = no adverse effect on integrity; grey = not determined; orange = potential effect)

6.5.4.2 Coastal lagoons

It has already been established in 5.1.5.1 that there is no possibility of an EQS exceedance for TRO in the lagoon site Neyland Weir Pool, the only lagoon site that was identified as being potentially affected by the PPS discharge, on the basis of distance and TRO decay. The other sources of discharges of toxic contaminants are all at least as far away from the lagoon, and the ‘alone’ assessments for the refinery discharges also concluded no adverse effect on integrity of the coastal lagoon feature. The SemLogistics discharge has been less studied but, even if this could be shown to be of concern, it would not represent an in combination effect with the PPS discharge on the coastal lagoon feature.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs because there is no possibility of an EQS exceedence for TRO.

6.5.4.3 Estuaries

As discussed in section 5.1.2, there is no evidence that there will be bioaccumulation of chlorinated and brominated chlorine by-products in the sea, so the potential effects of TRO on the estuaries interest feature can be regarded as relating to effects on pelagic and planktonic species within the mixing zone only.

- 172 - The PPS TRO discharge mixing zone (using 10µg/l as a 95 percentile as the boundary) will extend over 21ha at the sea surface and 5ha at the sea bed (Table 5.3). The equivalent mixing zone for TRO at South Hook LNG is estimated to be less than 1ha in area, on the basis that the TRO load is a factor of 1730 times less than for the proposed PPS discharge and the outfall is submerged at all times, giving greater initial dilution. Thus the total area within the two mixing zones will be less than 22ha. The mixing zones will both lie entirely within the estuaries feature. The estuaries interest feature occupies 5473ha within the SAC (Table 5.3); therefore 21ha represents 0.38% of the interest feature. Taking into consideration the findings from our extensive literature review, the EA has ascertained that effects of this magnitude do not represent an adverse effect on the integrity of the feature.

Conclusion

In conclusion, we believe that such effects as might arise from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs ,will not adversely affect the integrity of the site, because the scale of any impact is small and localised compared to the extent of the habitats likely to be affected.

6.5.4.4 Large shallow inlets and bays

This interest feature encompasses entirely the estuaries interest feature within the area containing the mixing zones but relates only to the biological community associated with the seabed (benthic infauna, epibenthos, attached plants and demersal fish). It could be argued that the size of mixing zone at the seabed is the relevant criterion here but this does not take account of the fact that the interest feature includes inter-tidal areas, which will be subjected to exposure to surface waters as the tide rises and falls. As the outfalls concerned are close to the shore and the mixing zone for the proposed PPS discharge includes a substantial inter- tidal area, a precautionary approach has been adopted and the area of the mixing zone at the sea surface has been used to assess the effects. The PPS TRO discharge mixing zone (for 10µg/l 95 percentile) will extend over 21ha at the sea surface and 5ha at the sea bed (Table 5.4), while the equivalent mixing zone for TRO at South Hook LNG is estimated to be less than 1ha in area (as described under section 6.5.4.3), giving a total area of sea surface within the two mixing zones of less than 22ha. The mixing zones will both lie entirely within the large shallow inlets and bays feature. The large shallow inlets and bays interest feature occupies 22091ha in total within the SAC (Table 5.4), therefore the mixing zones occupy 0.10% of the interest feature. Taking into consideration the findings from our extensive literature review and modelling work, the EA has ascertained that effects of this magnitude do not represent an adverse effect on the integrity of the feature.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs.

- 173 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 6.5.4.5 Mudflats and sandflats not covered by seawater at low tide

This interest feature relates to the benthic biological community in these habitats. It could be argued that the size of mixing zone at the seabed is the relevant criterion here but this does not take account of the fact that the interest feature comprises inter-tidal areas, which will be subjected to exposure to surface waters as the tide rises and falls. As the outfalls concerned are close to the shore and the mixing zone for the proposed PPS discharge includes a substantial inter-tidal area, a precautionary approach has been adopted and the area of the mixing zone at the sea surface has been used to assess the effects. The PPS TRO discharge mixing zone (using 10µg/l as a 95 percentile for the boundary) will extend over ~18ha of the mudflats and sandflats interest feature at the sea surface (Table 5.5), representing 1% of the interest feature area of 1779ha within the SAC. The discharge at South Hook LNG is located near the end of the ship jetty, as shown in Map 2, in a minimum water depth of about 7m, and is submerged. The nearest areas of the mudflat and sandflat interest feature are a small area of 0.2ha at the landfall of the South Hook LNG jetty, 925m inshore of the outfall location, and another of similar size 1150m north east of the outfall near Gelliswick. Other areas are at least 1.5km from the outfall. The north- south extent of the PPS sea surface mixing zone is 730m. In terms of load ratios, the South Hook mixing zone would be expected to extend only a small fraction of this distance in a north-south direction and taking into account the smaller north-south extent of the tidal excursion plot at South Hook (1.2km) compared with Pennar Mouth (2.5km), it is very unlikely that this mixing zone will impinge at all on the mudflats and sandflats interest feature. Thus there will be no in combination adverse effect on the interest feature.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs.

6.5.4.6 Reefs

The ‘alone’ assessment (section 5.1.5.5) finds that there is no reef habitat within the TRO mixing zone (for 10µg/l 95 percentile) for the proposed PPS discharge at the sea bed. As there is no effect from the PPS discharge we believe there is no potential for in combination effects, based on the assumption that effects could only arise through exposure to levels of toxic contaminants present at levels exceeding the EQS. While there are reefs in the vicinity of several of the other discharges containing toxic contaminants, many of these will be protected because the plumes are buoyant, so will also have a small mixing zone at the sea bed.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs.

- 174 - 6.5.4.7 Sandbanks which are slightly covered by seawater all the time

The ‘alone’ assessment (section 5.1.5.6) concludes that, as the sandbanks feature is located entirely outside the Haven, and given the distances involved 10km from the proposed PPS discharge to the mouth of the Haven, and the labile nature of the contaminants of concern (TRO), there will be no adverse effect on the conservation objectives of the sandbanks. The only potential for an in combination effect would therefore be if the plume from the PPS was added to by other TRO discharges to raise concentrations above the EQS, or if there were any chemical reactions to produce highly toxic compounds as a result of TRO mixing with contaminants from other discharges in the Haven. The mixing zones for the PPS discharge and the South Hook discharge are too far apart for the former to be a possibility and examination of substances in other discharges has not identified any substances that would react with TRO at the very low concentrations that would be involved at the points where the discharges would interact.

Conclusion

In conclusion, we believe that such effects as might arise from toxic contamination entering Milford Haven from this discharge, in combination with other PPPs ,will not adversely affect the integrity of the site with respect to it’s ability to support the sandbanks feature. This is because the location and scale of any impact is small and localised compared to the extent of the habitats likely to be affected.

6.5.4.8 Sea caves

The ‘alone’ assessment (section 5.1.5.7) concludes that, as the sea caves feature is located entirely outside the Haven, and given the distances involved, >3km from the proposed PPS discharge to the mouth of the Haven, and the labile nature of the contaminants of concern (TRO), there will be no adverse effect on the conservation objectives of seacaves. The only potential for an in combination effect would therefore be if the plume from the PPS was added to by other TRO discharges to raise concentrations above the EQS, or if there were any chemical reactions to produce highly toxic compounds as a result of TRO mixing with contaminants from other discharges in the Haven. The mixing zones for the PPS discharge and the South Hook discharge are too far apart for the former to be a possibility and examination of substances in other discharges has not identified any substances that would react with TRO at the very low concentrations that would be involved at the points where the discharges would interact.

Conclusion

In conclusion, we believe that such effects as might arise from toxic contamination entering Milford Haven from this discharge, in combination with other PPPs ,will not adversely affect the integrity of the site with respect to its ability to support the sea caves feature. This is because the location and scale of any impact is small and localised compared to the extent of the habitats likely to be affected.

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6.5.4.9 Grey seal

The ‘alone’ assessment for the proposed PPS discharge (section 5.1.5.8) concludes that, as seals only spend a small amount of time in the estuary and as TRO does not tend to bioaccumulate in the seals’ food chain, the risk of direct or indirect effects on seals is low. In addition, seals are able to detect and exhibit avoidance responses to adverse conditions. On this basis, and as the combined area of the mixing zones of all the effluents containing toxic contaminants is small compared with the area available to seals within the SAC, no in combination effects on the conservation status of this interest feature are predicted.

Conclusion

In conclusion, we believe that such effects as might arise from toxic contamination entering Milford Haven from this discharge, in combination with other PPPs ,will not adversely affect the integrity of the site with respect to its ability to support the grey seal feature. This is because the location and scale of any impact is small and localised compared to the area of the site seals are able to utilise and the toxins concerned do not tend to bioaccumulate in the seals’ food.

6.5.4.10 Anadromous fish

The key requirement for anadromous fish in estuaries is that a passage is available at all times that adults or juveniles wish to migrate and does not entail exposure to hazards that might compromise their breeding ability or the ability of the juveniles to return to the sea or in the case of river lamprey, often to suitable estuarine habitat. The breeding process takes place in fresh water, so the most sensitive juvenile stages do not enter the estuary. As set out in section 5.1.5.9, fish are also able to exhibit avoidance reactions, provided a clear route is available to them. The ‘alone’ assessment for the proposed PPS discharge establishes that the TRO mixing zone will only extend part way across the Haven and that the extent of lateral spread below the surface layers will be much less, with the mixing zone occupying a maximum of 15% of the estuary cross-section. The only other discharge containing TRO is at South Hook, shown in map 2, which will generate a very small mixing zone 6.5km to the west, so no in combination effect in terms of providing a barrier to fish migration will occur between these two discharges. The only discharge where there is potential for a barrier effect in combination with the PPS discharge is that from SemLogistics at Waterston. The issue here is mainly the combined effect of thermal plumes and this is dealt with in section 6.6. There are no toxic components present in the SemLogistics discharge that would be expected to form a barrier to fish after initial dilution that will be achieved close to the outfall. As there will be no barriers to fish migration established as a result of discharges of TRO in the proposed PPS cooling water discharge in combination with other discharges of TRO, and as the potential adverse effects on fish of the abstraction licence will be addressed through design of a fish return system, there will be no in combination effects on the anadromous fish interest features between TRO in the PPS discharge and the PPS cooling water abstraction.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1, in combination with other PPPs.

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6.5.4.11 Otter

The ‘alone’ assessment for the proposed PPS discharge (section 5.1.5.10) concludes that, as otters are mobile and as TRO does not tend to bioaccumulate in their food chain, the risk of direct or indirect effects on otters is low. In addition, otters are able to detect and exhibit avoidance responses to adverse conditions. On this basis, and as the combined area of the mixing zones of all the effluents containing toxic contaminants is small compared with the area available to otters within both SACs, no in combination effects are predicted.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from toxic contamination entering Milford Haven via the proposed PPS discharge from W1 in combination with other PPPs.

6.5.5. Summary of in combination effects of toxic contamination In conclusion, the EA has assessed the potential impacts of toxic contamination on Pembrokeshire Marine/Sir Benfro Forol SAC and the Cleddau Rivers/Afonydd Cleddau SAC, in view of these sites conservation objectives. We believe that such effects as might arise will not adversely affect the integrity of the site, because the scale of any impact is small compared to the size and diversity of the site, and the habitats and species concerned are resilient and adaptable particularly when considered across the whole site.

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6.6. Changes in thermal regime

6.6.1. Sources of the hazard

The source of thermal effects arising from the proposed PPS is: ƒ the cooling water discharge (W1) at a flow of 3456000m3/d at a maximum of 7.6°C above the intake temperature, plus a maximum temperature of 30.4°C.

Other PPPs that give rise to thermal inputs are:

ƒ thermal loads from submerged combustion vaporisers at South Hook LNG, with a maximum permitted flow rate in discharge W2 of 1000m3/d and maximum temperature of 30°C; changes in thermal loads compared with previous discharges are addressed in the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' report (BW9816/XP3535ME (SHLNG) and BT7817/HP3238LJ (DLNG) 13th July 2007); ƒ thermal loads in the discharge (W1) from the effluent treatment plant for process waters from the Milford Haven (Murco) Refinery, with a maximum permitted flow rate of 25000m3/d and maximum permitted temperature of 27°C. The Stage 3 Appropriate Assessment report 1st August 2007 (under the former operation by Total) reported on the assessment undertaken as part of the Review of Consents; however, this considered the actual discharge temperatures (average 13°C), which is much lower than the maximum permitted temperature, due to natural cooling in the route through the effluent treatment plant. For this assessment the maximum permitted temperature has been used in accordance with Environment Agency guidance; ƒ thermal loads in the discharge (W1) from the effluent treatment plant for process waters from the Pembroke (Chevron) Refinery, with a maximum permitted flow rate of 25000m3/d and maximum permitted temperature of 35°C. The Stage 3 Appropriate Assessment report 1st August 2007 reported on the assessment undertaken as part of the Review of Consents; ƒ thermal loads in the discharge (C) from the effluent treatment plant for process waters (including those from Dragon LNG) on the SemLogistics Waterston site, with a maximum permitted flow rate of 10000m3/d and maximum permitted temperature of 30°C, which serves the operations of both SemLogistics and Dragon LNG at Waterston. No previous Habitats Regulations Assessment has been identified.

6.6.2. Mechanisms for in combination effects

In combination effects relating to thermal loads can arise through: ƒ effects in the water column on mobile interest features or on juvenile stages of typical species of non-mobile interest features, due to plume overlap creating EQS exceedances or due to exposure of migratory fish to multiple pressures, if they migrate through a number of mixing zones en route through Milford Haven; ƒ spatially separate local effects on non-mobile interest features which in combination add up to a sufficient effect on that interest feature to represent an adverse effect on site integrity.

- 178 - The proposed thermal characteristics of the PPS cooling water discharge to Milford Haven have been discussed in detail in section 5.2. Results of dispersion modelling of the thermal loads from the proposed PPS presented in Figures 5.8 and 5.9 show the mixing zone (within which here the temperature rise MAC of 2°C as a maximum will be exceeded, taking data across a complete equinoctal spring-neap tide cycle). The analysis shows that, whenever the criterion (set by WQTAG160) of a maximum temperature rise (MAC) above ambient of 2°C is met, the criterion of a maximum temperature in the receiving water of 21.5°C as a 98%ile will also be met outside the mixing zone, so the rest of this part of the assessment concentrates on the 2°C maximum temperature rise MAC. Section 5.2.1 also explains that a long term background temperature rise within Milford Haven of 1.1°C is predicted within part of the central Haven. As expected, bearing in mind that the cooling water will be buoyant in the receiving environment due to its elevated temperature, the zone of exceedance at the bed is much smaller than at the sea surface. The most westerly (seaward) extent of the mixing zone boundary (for a 2°C maximum temperature rise) is: ƒ at the sea surface: 4km, to a point off the port authority jetty at Hakin; ƒ at the sea bed: 1.5km, to a point off Pwllcrochan Stream.

The maximum extent of the mixing zone boundary northwards (off the shore) is: ƒ at the sea surface: as far as the north shore; ƒ at the sea bed: 750m.

Other thermal loads in aqueous discharges to Milford Haven arise from: ƒ South Hook LNG;ook LNG (submerged combustion vaporisers effluent); ƒ Pembroke (Chevron) Refinery (effluent treatment plant); ƒ Milford Haven (Murco) Refinery (effluent treatment plant); ƒ SemLogistics, Waterston (effluent treatment plant).

Thermal loads compared with those of the proposed PPS discharge are estimated in Table 6.6, based on permitted values in the effluents and a minimum inlet water temperature of 5°C. It is clear that the thermal loads arising from process waters at oil and gas installations are much lower (five times or more) than the thermal loads associated with the PPS cooling water. Note also that the PPS load is based on predicted temperature rise, as the permit limits have not yet been set, while the oil and gas installation loads are based on permitted values and in practice loads emitted are very much lower.

Table 6.6 – Thermal loads relating to PPPs included in the assessment

Plan, project or permission (PPP) Temperature Change in Maximum Thermal % of PPS limit temperature flow rate loading load

Pembroke Power Station (PPS) 3 7.6°C 3456000m /d 1287MW - environmental permit 30.4°C

South Hook LNG (W2) 30°C 25°C 1000m3/d 1.2MW 0.1%

Murco Refinery (W1) 27°C 22°C 25000m3/d 26.7MW 2.1%

Chevron Refinery (W1) 35°C 30°C 25000m3/d 36.5MW 2.9%

SemLogistics Waterston (C) 30°C 25°C 10000m3/d 12.2MW 1.0%

- 179 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 6.6.3. Potential in combination effects from other hazards

Thermal plumes may affect the toxicity hazard presented by ammonia, by increasing the proportion of non-ionised ammonia, the main toxic fraction, and by affecting growth of certain algae which may smother other habitats. The latter is addressed in section 6.10. At a typical winter sea temperature89 of 5°C, a pH of 8 and a salinity of 34, a temperature rise of 2°C will increase the concentration of non-ionised ammonia as a proportion of total ammonia from 0.97% to 1.14% (using an Environment Agency algorithm developed by Andrew Wither, in the EA science team). At maximum monthly mean summer temperatures of 18°C, the increase in the proportion of non-ionised ammonia will be from 2.68% to 3.11%. Thus there is potential for an increase in the area of mixing zones where non-ionised ammonia concentration exceeds the EQS of 21µg/l (as N). This is of relevance in the case of the two refineries, which have permitted emission concentration limits for ammonia of 16mg/l (Murco) and 20mg/l (Chevron). Considering the process contributions of 0.42mg/l (as N) and 0.16mg/l (as N) respectively (taken from the Stage 3 Appropriate Assessment reports), a temperature rise of 2°C, with the receiving water temperature at 18°C (maximum thermal footprint scenario), would result in non-ionised ammonia process concentrations of 13µg/l and 5µg/l, both well within the EQS. Background concentrations of total ammonia throughout the main body of Milford Haven are low, therefore this mechanism will not give rise to in combination effects with the effects of discharges from the proposed PPS. The solubility of dissolved oxygen is reduced by increased temperature, which can therefore affect dissolved oxygen concentrations close to saturation. Temperature rise will also increase in situ biochemical oxygen demand (BOD), potentially reducing dissolved oxygen concentrations in areas of lower aeration of the water. However, water in Milford Haven is generally well oxygenated and environmental BOD concentrations are low90. We therefore believe, that the interaction (in combination) of increased temperature with other parameters that determine dissolved oxygen concentrations, will not adversely affect the integrity of the site with respect to it’s ability to support the habitats and species for which it is designated. Further details supporting this analysis can be found within section 5.2.5. In addition, any effects of thermal loads on migratory fish could act in combination with effects on fish populations of impingement and entrainment of fish through abstraction of cooling water.

6.6.4. In combination effects on interest features

6.6.4.1 Overview

Table 6.7 identifies which interest features could be affected by each of the PPPs where thermal changes are a potential hazard arising from the permission, based on information from the ‘alone’ assessments where available. Cells are colour coded according to the results of each ‘alone’ assessment – green = no LSE; yellow = no adverse effect on integrity from AA; orange = not determined; grey = no hazard identified from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix.

89 RWE (2010) Pembroke EP Application - Appropriate Assessment Supporting Document – Volume 2 90 Stage 3 Review of Consents for Pembrokeshire Marine SAC. 2007

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Table 6.7 – Interest features potentially affected by thermal loads from PPPs included in the assessment

Plan, project or permission (PPP) Lagoons Lagoons Estuaries inlets Large shallow & bays & sandflats Mudflats intertidal Reefs Atlantic salt meadows slightly Sandbanks covered Sea caves Grey seal Anadromous fish spp) (4 Otter Pembroke Power Station (PPS) environmental permit

South Hook LNG (W2)

Murco Refinery (W1)

Chevron Refinery (W1)

SemLogistics Waterston (C) Note: Cells are colour coded according to the results of each ‘alone’ and in combination assessment – green = no LSE; yellow = no adverse effect on integrity; grey = not determined; orange = potential effect)

6.6.4.2 Estuaries

Effects of thermal loads on the estuaries interest feature are discussed in detail in section 5.2.6.1. The PPS thermal discharge mixing zone (for a 2°C temperature rise as a maximum) will extend over 544ha at the sea surface and 135ha at the sea bed (Table 5.13). The other thermal loads identified all discharge into the same zone of Milford Haven which has a fairly consistent tidal regime (Figures 6.3 to 6.5), thus similar dispersion characteristics can be ascertained. As the other loads are small compared with the proposed cooling water thermal loads from the PPS, it can safely be assumed that the mixing zones (for a 2°C temperature rise as a maximum) will all be very small compared with that for the proposed PPS. Without details of the discharge depth and outfall design characteristics of each outfall, it is not possible to estimate initial dilution characteristics as the thermal effluent rises to the sea surface (which may be significant) or accurately to model the subsequent dispersion. However, assuming that water densities, flow rates and initial dilution characteristics were the same, for a thermal load of 50% of the predicted PPS load, for example, the area enclosed within the 4°C contour for the proposed PPS discharge would give an indication of the area which would lie within the 2°C contour for the smaller discharge, provided that this area was not so small as to be within the initial dilution zone.

- 181 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The other discharges are all essentially fresh water, so will be less dense, flow rates are much lower and initial dilution is likely to be greater, as the outfalls are all submerged. However, taking all these into account, it is still possible to assert with a high degree of confidence that the mixing zones will all be considerably smaller than outlined by the 4°C contour obtained from modelling of the proposed PPS discharge. A rise of 4°C is the highest temperature rise plotted in the Pembroke EP Application Appropriate Assessment Supporting Document91, so this has been used to define a worst possible case for the smaller discharge mixing zones. These plots actually relate to a temperature rise across the PPS of 8.1°C and a flow of 38m3/s but this amounts to 1300MW - virtually the same load as set out in Table 6.6. On the basis of these plots, the mixing zone characteristics for the other thermal discharges (maximum extent at any time over a spring neap cycle) at the sea surface, taking this highly precautionary approach, can be quoted as: ƒ maximum extent westwards - <500m; ƒ maximum extent eastwards - <800m; ƒ maximum extent off from shore - <650m; ƒ area - <56ha. For the sea bed he equivalent values can be quoted as: ƒ maximum extent westwards - <350m; ƒ maximum extent eastwards - <650m; ƒ maximum extent off from shore - <500m; ƒ area - <25ha. As the mixing zones will certainly be considerably smaller than indicated by these values, due to our precautionary assumptions, with the South Hook LNG zone probably occupying less than 1ha due to its very small thermal load, it is clear that the mixing zones for South Hook LNG and the Murco and Chevron refineries will not overlap with the sea surface mixing zones for the proposed PPS discharge plotted in Figures 5.8 and 5.9, although that for Chevron may be close. Thus there is no potential for these thermal loads to create fields of higher temperature within the PPS mixing zone than indicated in Figure 5.9. It is also worth noting that although Murco and Chevron’s permit include maximum temperature limits of 27°C and 35°C respectively, both permits include a condition which requires them to submit detailed modelling before they discharge at temperatures above 21.5°C. To date, both have discharged at or below this limit. Therefore there is additional confidence that neither of these discharges could overlap or have any additional in combination effects with the proposed PPS discharge. However, the mixing zone for the SemLogistics discharge could overlap with the PPS thermal discharge mixing zone and contribute to an increased single zone of temperature exceedance (at the sea surface only) within the interest feature. However, it must be noted that this is a very precautionary assessment as for 95% of the time the predicted areas will be considerably smaller. The estuaries interest feature occupies 5473ha within the SAC (Table 5.12); therefore the depth averaged area of 340ha for the PPS mixing zone represents 6.2% of the interest feature. Taking the South Hook discharge mixing zone as being likely to be insignificant, addition of a depth averaged maximum area of 41ha for each of Murco, Chevron and SemLogistics discharges, the percentage of the interest feature potentially affected will rise, although the total figure will certainly be less than 8.5%.

91 Volume 3b Appendices, Appendix 6.4. Modelled Temperature Rise (CES Appendix AI.6.2) - 182 - Conclusion

The thermal discharges from SemLogistics may overlap with the mixing zone for the proposed PPS thermal discharge and the mixing zones for the refineries. Our precautionary analysis indicates that for short periods this could result in 8.5% of the estuary interest feature being affected, although 95% of the time the area will be considerably less. SemLogistics may have an in combination effect with the proposed PPS thermal discharge by increasing 2.3% of the estuaries interest feature, affected by a temperature rise of more than 2°C. However, this will not result in direct habitat loss and will only occur occasionally. We believe that, based on the findings in Section 5.2.6.1 and this additional assessment, that such effects as might arise, from the in combination effects of the thermal mixing zones, will not adversely affect the integrity of the site. This is because of the scale of any impact and the nature of the features concerned, which we believe are resilient and adaptable to thermal effects when considered across the whole site and in the context of prevailing diurnal and season temperature fluctuations.

6.6.4.3 Large shallow inlets and bays

This interest feature encompasses much of the potentially affected area that is included in the estuaries interest feature (but not Pembroke River) but relates only to the biological community associated with the seabed (benthic infauna, epibenthos, attached plants and demersal fish). It could be argued that the size of mixing zone at the seabed is the relevant criterion here but this does not take account of the fact that the interest feature includes inter-tidal areas, which will be subjected to exposure to surface waters as the tide rises and falls. As the outfalls concerned are close to the shore and the mixing zone for the proposed PPS discharge includes a substantial inter-tidal area, a precautionary approach has been adopted and the area of the mixing zone at the sea surface has been used to assess the effects. The PPS thermal discharge mixing zone (for a 2°C temperature rise MAC) will extend over 543ha of the large shallow inlets and bays interest feature at the sea surface, representing 2.5% of the interest feature area of 22091ha within the SAC (Table 5.13). Taking the South Hook discharge mixing zone as being likely to be insignificant, addition of a sea surface maximum area of <56ha for each of Murco, Chevron and SemLogistics discharges, the percentage of the interest feature potentially affected will rise, although the total figure will be less than 3.0%. Taking into consideration the findings from our extensive literature review, we believe that effects of this magnitude do not represent an adverse effect on the integrity of the site because of the scale of any impact and the nature of the features concerned, which we believe are resilient and adaptable to thermal effects when considered across the whole site and in the context of prevailing diurnal and season temperature fluctuations.

Conclusion

The thermal discharges from SemLogistics may overlap with the mixing zone for the proposed PPS thermal discharge and the mixing zones for the refineries. However, this is a precautionary result, as for 95% of the time the area will be considerably less. SemLogistics may have an in combination effect with the proposed PPS thermal discharge by increasing by 0.5% the proportion of the large shallow inlets and bays interest feature affected by a temperature rise of more than 2°C. However, based on the findings in Section 5.2.6.2 and this additional assessment, we believe that such effects as might arise, from the in combination effects of the thermal mixing zones, will not adversely affect the integrity of the site. This is because of the scale of any impact and the nature of the features concerned, which we believe are resilient and adaptable to thermal effects when considered across the whole site and in the context of prevailing diurnal and season temperature fluctuations.

- 183 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 6.6.4.4 Mudflats and sandflats not covered by seawater at low tide

This interest feature relates to the benthic biological community in these habitats. It could be argued that the size of mixing zone at the seabed is the relevant criterion here but this does not take account of the fact that the interest feature comprises of inter-tidal areas, which will be subjected to exposure to surface waters as the tide rises and falls. As the outfalls concerned are close to the shore and the mixing zone for the proposed PPS discharge includes a substantial inter-tidal area, a precautionary approach has been adopted and the area of the mixing zone at the sea surface has been used to assess the effects. The PPS thermal discharge mixing zone (using a 2°C temperature rise maximum as the boundary) will extend over 183ha of the mudflats and sandflats interest feature at the sea surface (Table 5.15), representing 10.3% of the interest feature area of 1779ha within the SAC. Plotting the additional maximum extent of the mixing zones at the sea surface for the other thermal discharges indicates that up to an additional 10ha of the interest feature may be subject to temperature rises exceeding 2°C. This would bring the overall percentage of the interest feature area potentially affected up to 10.8%. Although this is a significant proportion of the feature, as it is currently understood to be distributed on the site, represents the worst case scenario. Ninety-five percent of the time the predicted areas will be considerably less. This interest feature is naturally subject to wide and rapid variations in temperature due diurnal (and tidal) and season temperature fluctuations. The mixing zone for the SemLogistics discharge may overlap with the PPS thermal discharge mixing zone and contribute to an increased single zone of temperature exceedance (at the sea surface only) but there are only minimal areas of the mudflat and sandflat interest feature within this overlap zone. We therefore believe that such effects as might arise, from the in combination effects of the thermal mixing zones, will not adversely affect the integrity of the site.

Conclusion

The thermal discharges from SemLogistics could overlap with the mixing zone for the proposed PPS thermal discharge and the mixing zones for the refineries. SemLogistics may have an in combination effect with the proposed PPS thermal discharge by increasing the proportion of ‘mudflats and sandflats not covered by seawater at low tide interest feature’ affected by a temperature rise of more than 2°C, by 0.7%. However, based on the findings in Section 5.2.6.3 and this additional assessment, we believe that such effects as might arise, from the in combination effects of the thermal mixing zones, will not adversely affect the integrity of the site. This is because of the scale of any impact and the nature of the features concerned, which we believe are resilient and adaptable to thermal effects when considered across the whole site and in the context of prevailing diurnal and season temperature fluctuations.

- 184 - 6.6.4.5 Reefs

The reef feature is predominantly submerged, so the relevant mixing zone is that at the sea bed. The ‘alone’ assessment (section 5.2.6.4) concludes that the PPS thermal discharge mixing zone at the sea bed (for a 2°C temperature rise MAC) will extend over 4.4ha of the reef feature, representing 0.01% of the interest feature area of 41007ha within the SAC. Taking the South Hook discharge mixing zone as being likely to be insignificant, examination of the expected sea bed mixing zone of <25ha for each of Murco, Chevron and SemLogistics discharges, shows that for the Murco discharge about 50% of the mixing zone would be over reef habitat, for Chevron the figure is approximately 10% and for SemLogistics approximately 80%. Including these areas, the total area of reef interest feature potentially affected by thermal discharges will rise but the total figure will certainly be less than 0.4% of the total area of reef interest feature within the SAC. Taking into consideration the findings from our extensive literature review and modelling work, the EA has ascertained that effects of this magnitude do not represent an adverse effect on the integrity of the feature.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from thermal discharges entering Milford Haven via the proposed PPS cooling water discharge (W1), in combination with other PPPs.

6.6.4.6 Grey seal

The ‘alone’ assessment for the proposed PPS discharge (section 5.2.6.5) identifies that seals are able to detect and exhibit avoidance responses to adverse conditions. They are very cosmopolitan in their diet, switching prey if necessary, and are therefore well adapted to adjust to any change in the balance of species in fish populations resulting from the thermal discharges. Thus the risk of direct or indirect effects on seals is low. On this basis, and as the combined area of the mixing zones of all the effluents containing toxic contaminants is small compared with the area available to seals within the SAC, no in combination effects on the conservation status of this interest feature are predicted.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from thermal loads entering Milford Haven via the proposed PPS cooling water discharge (W1) in combination with other PPPs.

6.6.4.7 Anadromous fish

Lamprey and shad are known to be sensitive to temperature variation and use temperature as a trigger to migrate inland. An increase in overall temperature within Milford Haven may encourage earlier upstream migration of lamprey, although it would not affect onset of spawning or juvenile development, as this takes place in non-tidal rivers. With commissioning of the PPS, an overall background temperature rise of 1°C is predicted within part of the central Haven. Based on loadings in Table 6.6, the PPS discharge will contribute 94% of loads entering via thermal discharges. The inputs of the other discharges are small compared with typical variations in heat fluxes with the weather. On this basis, the additional thermal loads from the other permitted discharges will not have a significant effect on background temperatures in combination with the proposed PPS discharge.

- 185 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 The key requirement for anadromous fish in estuaries is that a passage is available at all times that adults or juveniles wish to migrate which does not entail exposure to hazards that might compromise their breeding ability or the ability of the juveniles to return to the sea or in the case of river lamprey often to suitable estuarine habitat. The breeding process takes place in fresh water, so the most sensitive juvenile stages do not enter the estuary. Fish are also able to exhibit avoidance reactions, provided a clear route is available to them. The ‘alone’ assessment establishes that the thermal mixing zone from the proposed PPS (for a 2°C temperature rise as a maximum) will only extend across the Haven at the sea surface and that the extent of lateral spread below the surface layers will be much less, as shown in Figure 5.11, which relates to low water on a spring equinoctal tide. Thus the thermal discharge will not present a barrier to fish migration. Further detail on this can be found within section 5.2.6.6. The discharges from South Hook LNG and the Murco and Chevron refineries will produce much smaller mixing zones (for a 2°C temperature rise as a maximum) in areas where the Haven is wider and deeper than off the proposed PPS discharge and will not overlap with the mixing zone for thermal discharges from the PPS. Thus there will be no barriers to migration established by effects in combination with these emissions. However, the SemLogistics discharge mixing zone will overlap with the PPS thermal mixing zone at the sea surface but not at the sea bed, as the PPS and SemLogistics outfalls are offset by 900m, see map 1, in an east-west direction, so will not create a barrier to fish migration in combination. Thus there will be no barrier to migration established by effects in combination with this emission. As there will be no barriers to fish migration established as a result of discharges of thermal loads in the proposed PPS cooling water discharge in combination with other discharges of thermal loads and as the potential adverse effects on fish of the abstraction licence will be addressed through design of a fish return system, there will be no in combination effects on the anadromous fish interest features between the thermal load of the PPS discharge and the PPS cooling water abstraction.

Conclusion

The ‘alone’ assessment establishes that the thermal mixing zone from the proposed PPS (for a 2°C temperature rise as a maximum) will only extend across the Haven at the sea surface and that the extent of lateral spread below the surface layers will be much less, as shown in Figure 5.11. We believe that such effects as might arise, from the in combination effects of the thermal mixing zones, will not adversely affect the integrity of the site. This is because the in combination effect of the thermal mixing zones will still not result in a barrier to fish migration.

6.6.4.8 Otter

The ‘alone’ assessment for the proposed PPS discharge (section 5.2.6.7) identifies potential indirect effects on otters through effects of thermal loads on availability of prey species. However, otters take a wide range of prey, including non-fish prey, and are therefore well adapted to adjust to any change in the balance of species in fish populations resulting from the thermal discharges. In addition, otters are able to detect and exhibit avoidance responses to adverse conditions. Thus the risk of direct or indirect effects on otters is low. On this basis, and as the combined area of the mixing zones of all the thermal inputs is small compared with the area available to otters within both SACs, no in combination effects are predicted.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from thermal loads entering Milford Haven via the proposed PPS cooling water discharge (W1), in combination with other PPPs.

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6.6.5. Summary of in combination effects of thermal loads

Thermal loading from discharges entering Milford Haven via the proposed PPS cooling water discharge (W1) will not have an adverse effect, in combination with other PPPs, on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC or the Cleddau Rivers/Afonydd Cleddau SAC.

- 187 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

6.7. Nutrient enrichment

6.7.1. Sources of the hazard

The Milford Haven waterway is hypernutrified; both the Inner and Outer Haven are less than “Good” for the WFD nutrient regulatory standard based on dissolved inorganic nitrogen (DIN). The Inner and Outer Haven water bodies are classified as “Moderate” and “Good” for macro- algae respectively. Both water bodies are classified as “High” for phytoplankton. Growth of algae in the waterway can potentially be limited by either DIN (comprising mainly ammonia and nitrate) or dissolved inorganic phosphorus (DIP). A number of reports suggest that algal growth in the Inner Haven is mainly limited by phosphorus rather than nitrogen, while the reverse may be true in the Outer Haven. For example, the CEFAS modelling report (Aldridge & Painting 2011) suggests that while the overall Haven may be P-limited for 2% of the time, the Inner Haven may be P-limited for about 50% of the time. Therefore, any significant increase in either nutrient could potentially result in an adverse effect on site integrity. As set out in section 5.3.3, inorganic nutrient content in the discharge from the PPS, in addition to nutrients already present in the estuary water abstracted and discharged as cooling water, arises from use of water supply originating from the Eastern Cleddau plus an additional process contribution of ammonia in the boiler blowdown. The ‘alone’ assessment has considered the effects of the increase in nutrient concentrations at the point of discharge on the integrity of the Special Area of Conservation, with particular regard to the risk of increased macro-algal growth smothering the eelgrass beds within the Pembroke River Estuary/Pennar Gut. Sources of nutrients considered include the PPS cooling water discharge (W1) and all other point source and diffuse inputs (considered together). Concerns about nutrient enrichment normally relate to effects on loadings to and concentrations in Milford Haven, rather than local effects within effluent plumes, although such effects may be evident close to outfalls. The alone assessment has considered the effects of inputs of nutrients from the proposed PPS cooling water discharge in the context of the combined inputs from all other sources and therefore also fulfils the role of an assessment of effects in combination with all the existing point source inputs from discrete permitted discharges (sewage treatment works and industrial) as well as diffuse inputs via the rivers. The PPS discharge is expected to contribute the equivalent of 0.14% of the total DIN load of 6590kg/d (as N) and 0.18% of the existing DIP load of 166kg/d (as P)(Mitchell, 2009), although most of this “contribution” will be relocated from elsewhere in the same catchment. Furthermore, there will be an overall net reduction in the phosphorus load to the Haven resulting from the proposed off-site mitigation. The temporary sewage treatment plant is also estimated to input between 0.01% and 0.06% of total DIN loadings and between 0.01% and 0.1% of DIP loadings92. Any permanent sewage works is expected to have inputs at the low end of this scale. These will represent additional loads and have been considered again in the context of the combined inputs from all other sources. No separate in combination assessment with the PPS cooling water discharge is therefore required. The Likely Significant Effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' for this PPS Environmental permit, considered the emissions of NOx, acid deposition and nutrient nitrogen deposition. Each assessment found that the air emissions were either de-minimus or below the critical levels for each protected site. The nutrient emission figures from this report have been taken into consideration within this in combination assessment with the PPS cooling water discharge, as shown in Table 6.12.

92 Appendix 11 report for PPS temporary sewage treatment plant. 13th November 2009. - 188 - All consented discharges to the Pembrokeshire Marine Special Area of Conservation (including the Milford Haven Waterway) were included in the Habitats Directive Review of Consents, which concluded in 2005/06 that there was no adverse effect on site integrity from point source nutrient inputs. Since 2006, however, monitoring for WFD has identified sometimes dense occurrence of seasonal intertidal macro-algal blooms on intertidal mudflats and sandflats within sheltered bays and inlets in the Haven. Surveys to assess the extent of these blooms and investigations into the factors controlling macro-algal growth in the Haven are ongoing as part fulfilment of Environment Agency responsibilities under the Water Framework Directive.

6.7.2. Mechanisms for in combination effects

In combination effects relating to nutrients can arise through:

ƒ Multiple sources of nutrients from the entire catchment area contributing to elevated nutrient concentrations and algal growth in the estuary ƒ Overlapping plumes from point sources and/or freshwater inputs to the estuary causing locally elevated concentrations affecting a specific feature ƒ Spatially separate plumes from point sources and/or freshwater inputs to the estuary which add up to a sufficient effect on a single interest feature to represent an adverse effect on site integrity ƒ Increased algal growth due the in-combination effects of elevated temperature and nutrients The alone assessment (Section 5.3) considered the effect of the increase in nutrient concentrations at the point of discharge in combination with nutrients from all other sources. Therefore, the remainder of this section focuses on the potential in combination effect of nutrients and temperature.

6.7.3. Potential in combination effects from other hazards

The principle concern regarding nutrients interacting with other hazards is the potential increase in growth of macro-algae due to elevations in both temperature and nutrients. The potential adverse effects of increased macro-algal growth are described in Section 5.3. The remainder of this section considers the potential for these effects to be exacerbated by an increase in temperature caused by the cooling water discharge. No in-combination effects from other hazards have been identified.

6.7.4. In combination effects on interest features

6.7.4.1 Habitat interest features

Effects of nutrient enrichment on habitat features within Milford Haven (lagoons, estuaries, large shallow inlets and bays, mudflats and sandflats not covered by seawater at low tide and reefs) are a function of nutrient loads to the Haven and are set out in section 5.3. This section considers the potential for these effects to be exacerbated by an increase in temperature caused by the cooling water discharge. The Pembroke River estuary/Pennar Gut contains about 75% of the inter-tidal eelgrass in the Milford Haven waterway. It also contains opportunistic green macro-algae (Enteromorpha) which can grow excessively and smother mudflats and eelgrass. The macro-algae is not extensive in this area, but where it grows it produces a large biomass (average over 1000g/m2). Modelling suggests that the proposed discharge is likely to increase the temperature in this region by an average of 0.7oC (Wither et al. 2011).

- 189 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 Temperature has been observed to affect opportunistic macro-algal growth in several ways (Lotze et al. (1999 & 2002), Valiela et al.(1997) 93 94 95 ƒ Germination of spores and juvenile recruitment ƒ Growth rate ƒ Length of growing season ƒ Herbivore activity Wither et al.(2011) assessed the effects arising from nutrients and thermal emissions from the power station using the Martins and Marques (2002) model for temperature effect alone, and the Cefas (Aldridge & Painting 2011) dCPM Milford Haven model for nutrients and temperature combined. In order to make quantitative estimates of the potential effect of a temperature increase associated with the power station on macro-algae, a simplified macro-algal model was used, based on the underlying growth and loss terms used by Cefas in the dCPM model. The temperature function used for the growth factor was as implemented by Martins and Marques, with a growth optimum of 15oC. Application of this model indicated that increased temperature could result in faster growth of macro-algae in the spring but could result in reduced biomass in the autumn. It was concluded that temperature in isolation or in combination with enhanced nutrients will not change the total biomass of macro-algae but will alter bloom dynamics to a limited extent. The assessment by Wither et al is considered to be based on the best available information, although it does rely on a number of assumptions about the factors controlling algal growth that are difficult to confirm. The assessment did not take into account the removal of process contributions of phosphorus from the power station discharge or off-site removal of phosphorus, which together should result in an overall net-reduction in phosphorus load to the SAC (and to the Pennar Gut). This extra reduction in phosphorus load is believed to be appropriate mitigation for the uncertainty about the assumptions used in the modelling. Overall it is likely that increases in algal growth, if any, resulting from the power station emissions will be negligible.

Conclusion

Based on the available information it is concluded that there will be no adverse effect on the integrity of the habitat interest features of the Pembrokeshire Marine/Sir Benfro Forol SAC/ Afonydd Cleddau / Cleddau Rivers SAC. from nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other hazards.

6.7.4.2 Species interest features

Effects of nutrient enrichment exacerbated by increased temperature on species interest features of the Pembrokeshire Marine/Sir Benfro Forol SAC or the Cleddau Rivers/Afonydd Cleddau SAC are possible through effects on prey species. However, as detailed in sections 5.3 and 6.7.4.1, the relatively small scale of any change is unlikely to cause a significant effect on populations of fish or mammals.

Conclusion

Based on the available information it is concluded that there will be no adverse effect on the integrity of the species interest features of the Pembrokeshire Marine/Sir Benfro Forol SAC from nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other hazards.

93 Morand and Brand (1996) add reference 94 Vanden Hock (1982) add reference 95 Raffaelli et al (1998) add reference - 190 -

6.7.5. Summary of in combination effects of nutrient enrichment Based on the available information it is concluded that there will be no adverse effect on the integrity of the habitat or species interest features of the Pembrokeshire Marine/Sir Benfro Forol SAC/ Afonydd Cleddau / Cleddau Rivers SAC. from nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other hazards.

- 191 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001

6.8. Habitat loss and physical damage

6.8.1. Sources of the hazard

This section considers physical loss or damage to habitat interest features and species interest features of the SACs. Sources of effects may include: ƒ the physical characteristics of the flow from the PPS cooling water discharge (W1); ƒ the PPS abstraction; ƒ PPPs involving construction activity affecting sea bed habitat; ƒ PPPs involving dredgings disposal.

6.8.2. Mechanisms for in combination effects

Habitat loss or physical damage (to habitats or species) may occur: ƒ directly through installation of structures, through erosion or dredgings disposal; ƒ directly through impingement and entrainment of species by abstraction intakes; ƒ indirectly due to eutrophication effects (e.g. algal mats on mudflats making the habitat unsuitable for the normal flora and fauna).

6.8.3. Potential in combination effects from other hazards

Physical habitat loss or damage to species could act in combination with adverse effects on the same habitat from toxic or thermal effects of the proposed PPS discharge from W1. Assessment of in combination effects of physical damage to fish with effects of TRO and thermal loads have been considered in section 5.4.

6.8.4. In combination effects on interest features

6.8.4.1 Overview

As described in section 5.4.2, at low tide, the proposed PPS cooling water discharge will emit water across an area of mudflat and sandflat interest feature via a narrow dredged channel at a volume of up to 40m3/s and a velocity of 1.6m/s, potentially causing minor amounts of erosion, which will reduce as an equilibrium situation is reached. Erosion and scouring is not expected to affect sub-tidal communities, as changes in velocity will be much lower than the dominant tidal flows.. The abstraction of cooling water for the PPS has potential to cause physical damage to fish species. This is the subject of a separate abstraction licence and this has already been assessed under the Habitats Regulations and the licence issued, with conditions concerning development of a fish return system. Operation of the proposed PPS cooling water discharge will have no direct physical effect on fish but loss of fish through abstraction could act in combination with potential negative effects on fish due to toxic and thermal components of the discharge. This has been considered earlier in section 6.5 and 6.6.

- 192 - The proposed PPS cooling water discharge could contribute to nutrient enrichment (in combination with nutrient sources from sewage works, industrial discharges, see Table 6.3, and diffuse sources), leading to eutrophication effects, such as growth of algal mats on mudflats, making the habitat unsuitable for its normal flora and fauna and affecting prey species for mobile interest features. However, as the nutrient loads from the PPS discharge will contribute minimal amounts of biologically available nutrients after the phosphate mitigation is in place, and thus have been determined in the ‘alone’ assessment to be insignificant (see section 5.3.3.1), this PPS discharge will not contribute to such effects and this aspect is not considered further. Table 6.9 identifies which interest features could be affected by each of the PPPs where physical habitat loss or damage to habitats or species are potential hazards arising from the permission, based on information from the ‘alone’ assessments where available. Cells are colour coded according to the results of each ‘alone’ assessment – green = no LSE; yellow = no adverse effect on integrity from AA; orange = not determined; grey = no hazard identified from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix.

Table 6.9 – Interest features potentially affected by habitat loss and physical damage from PPPs included in the assessment

Plan, project or permission (PPP) Lagoons Lagoons Estuaries inlets Large shallow & bays & sandflats Mudflats intertidal Reefs Atlantic salt meadows slightly Sandbanks covered Sea caves Grey seal Anadromous fish spp) (4 Otter Pembroke Power Station (PPS) environmental permit

Pembroke Power Station abstraction

Pembroke Power Station Sewage N N N N N Discharge

South Hook LNG (W2) N N N N N

Murco Refinery (W1) N N N N N

Chevron Refinery (W1) N N N N N

SemLogistics Waterston (C) N N N N N

Maintenance dredging 2010

Other sewage works discharges N N N N N

Mussel settlement trials

Angle Shelf Several Order Note: Cells are colour coded according to the results of each ‘alone’ and in combination assessment – green = no LSE; yellow = no adverse effect on integrity; grey = not determined; orange = potential effect. N – potential indirect effect only, due to nutrient enrichment leading to eutrophication

- 193 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 6.8.4.2 Estuaries and large shallow inlets and bays

The ‘alone’ assessment (section 5.4.2.1) ascertains that, erosion effects from the PPS discharge will be very localised. Therefore, the natural rate of flow from the tide will mean the momentum of the effluent will dissipate quickly with increasing distance from the outfall, and the habitats that occur in the vicinity will already be accustomed to tidal flows. As such, the effects on tidal flows and erosion/deposition in the estuaries interest feature and the large shallow inlets and bays feature will lead to no adverse effects on the features. Furthermore, in conducting the in-combination assessment with other PPPs it was concluded that there would be no overlaps with other relevant PPPs. Accordingly, there will be no in combination effect (whether additive, cumulative or synergistic) with those other PPPs where there is potential loss of habitat comprising these features. Maintenance dredging 2010, for the next 5 years, has been occurring since before the Pembrokeshire Marine SAC was designated and as such is considered to be part of the background activities by MHPA. The dredging is also not continuous, with MHPA finding that dredged areas are rapidly re-colonised with spoil tipped outside the SAC.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from habitat loss and physical damage as a result of small process contributions of ammonia and re-located nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other PPPs.

6.8.4.3 Mudflats and sandflats not covered by seawater at low tide

Section 5.4.2.2 describes the fact that, the PPS outfall channel across the mudflats has been reinstated and this now forms part of the prevailing environmental conditions against which the assessment is made. Due to this reinstatement, erosion will be limited to the channel and will not produce tracks across the mudflat that will migrate over time. Thus equilibrium will be reached whereby further loss of habitat will be halted and the biological community in the disturbed mudflat will recover. There will therefore be no in combination effect with other PPPs where there is potential loss of habitat comprising this feature. Maintenance dredging 2010, for the next 5 years, has been occurring since before the Pembrokeshire Marine SAC was designated and as such is considered to be part of the background activities by MHPA. The dredging is also not continuous, with MHPA finding that dredged areas are rapidly re-colonised with spoil tipped outside the SAC.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from habitat loss and physical damage as a result of small process contributions of ammonia and phosphate, plus re-located nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other PPPs.

6.8.4.4 Reefs

The ‘alone’ assessment in section 5.4.2.3 concludes that there will be no effect on reef habitat through physical processes arising from the PPS discharge from W1. Therefore there will be no in combination effects with other PPPs which may affect the reef interest feature. No maintenance dredging occurs within the vicinity of reefs.

- 194 -

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from habitat loss and physical damage as a result of small process contributions of ammonia and phosphate, plus re-located nutrients entering Milford Haven via the proposed PPS discharge from W1 in combination with other PPPs.

6.8.5. Summary of in combination effects of habitat loss or damage to interest features

There will be no adverse effects through habitat loss or physical damage from the PPS discharge from W1, in combination with other PPPs, on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC or the Cleddau Rivers/Afonydd Cleddau SAC. This is because the erosion effects are very localised around the power station outfall and because there are no overlaps between the power station and other PPPs. As a result, it has been concluded that there will be no in-combination effects (whether additive, cumulative or synergistic) arising as a result of the combined operation of the power station and other PPPs.

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6.9. Siltation and turbidity

6.9.1. Sources of the hazard

This section considers the effects of turbidity on interest features of the SACs. Sources of effects may include: ƒ suspension of sediments by the currents induced by the proposed PPS discharge from W1; ƒ PPPs involving dredging and disposal of dredgings; ƒ suspension of sediments by PPPs involving use of mussel dredges or trawl gear; ƒ suspension of sediments from PPPs involving marine construction projects; ƒ growth of phytoplankton (dealt with under nutrients in section 5.3).

6.9.2. Mechanisms for in combination effects

The baseline levels of turbidity in Milford Haven are relatively low compared with many estuaries. Effects of increased turbidity may include: ƒ effects on fish in the water column; ƒ changes in light availability affecting plant growth, for example seagrass; ƒ changes in habitat characteristics due to sedimentation. ƒ In combination effects could arise through: ƒ overlap of turbidity plumes creating higher levels of turbidity than each PPP alone; ƒ effects on ability of predators to catch food items; ƒ exposure of migratory fish to multiple turbidity plumes during migration through the estuary.

6.9.3. Potential in combination effects from other hazards

No potential in combination effects from other hazards are relevant in the case of siltation and turbidity.

6.9.4. In combination effects on interest features

6.9.4.1 Overview

Table 6.10 identifies which interest features could be affected by each of the PPPs where turbidity is a potential hazard arising from the permission, based on information from the ‘alone’ assessments where available. Cells are colour coded according to the results of each ‘alone’ assessment – green = no LSE; yellow = no adverse effect on integrity from AA; orange = not determined; grey = no hazard identified from the Likely significant effect assessment (Stage 2) - 'Appendix 11 EPR final revised Apr 11' risk matrix.

- 196 - Table 6.10 – Interest features potentially affected by siltation and turbidity from PPPs included in the assessment

Plan, project or permission (PPP) Lagoons Lagoons Estuaries inlets Large shallow & bays & sandflats Mudflats intertidal Reefs Atlantic salt meadows slightly Sandbanks covered Sea caves Grey seal Anadromous fish spp) (4 Otter Pembroke Power Station (PPS) environmental permit

South Hook LNG site run-off

SemLogistics Waterston (C)

Martello Quays

Maintenance dredging 2010

Neyland Marina trickle dredge and disposal

Mussel settlement trials

Angle Shelf Several Order Note: Cells are colour coded according to the results of each ‘alone’ and in combination assessment – green = no LSE; yellow = no adverse effect on integrity; grey = not determined; orange = potential effect.

6.9.4.2 Estuaries and large shallow inlets and bays

The ‘alone’ assessment (section 5.5.2.1) concludes that, as erosion effects from the PPS discharge will be very localised, the effects on tidal flows and erosion/deposition in the estuaries interest feature and the large shallow inlets and bays feature will lead to no adverse effects on the features. Furthermore, in conducting the in-combination assessment with other PPPs it was concluded that there would be no overlaps with other relevant PPPs. Accordingly, there will be no in combination effect (whether additive, cumulative or synergistic) with those other PPPs where there is potential loss of habitat comprising these features. Maintenance dredging 2010, for the next 5 years, has been occurring since before the Pembrokeshire Marine SAC was designated and as such is considered to be part of the background activities by MHPA. The dredging is also not continuous, with MHPA finding that dredged areas are rapidly re-colonised with spoil tipped outside the SAC.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

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6.9.4.3 Mudflats and sandflats not covered by seawater at low tides

The ‘alone’ assessment (section 5.5.2.2) identifies that many benthic invertebrates benefit from suspended matter as it represents food resource, and that inter-tidal organisms in the vicinity of the proposed PPS discharge are likely to be able to tolerate high turbidity. In the light of the low sensitivity of the biota of this interest feature and the very localised nature of the resuspension, turbidity will not lead to adverse effects on the conservation objectives of this interest feature. Furthermore, in conducting the in-combination assessment with other PPPs it was concluded that there would be no overlaps with other relevant PPPs. Accordingly, there will be no in combination effect (whether additive, cumulative or synergistic) with those other PPPs where there is potential loss of habitat comprising these features. Maintenance dredging 2010, for the next 5 years, has been occurring since before the Pembrokeshire Marine SAC was designated and as such is considered to be part of the background activities by MHPA. The dredging is also not continuous, with MHPA finding that dredged areas are rapidly re-colonised with spoil tipped outside the SAC.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

6.9.4.4 Reefs

Reef features are not particularly sensitive to turbidity. The ‘alone’ assessment in section 5.5.2.3 concludes that there will be no effect on reef habitat through turbidity generated by sediment resuspension by the PPS cooling water discharge, therefore there will be no in combination effects with other PPPs which may affect the reef interest feature. No maintenance dredging occurs within the vicinity of reefs.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

6.9.4.5 Grey seal

Grey seal may experience a change in the distribution of prey items due to turbidity plumes at different points in the estuary, which may be beneficial or adverse but, as they are able to detect and exhibit avoidance responses to adverse conditions and to switch prey if necessary, they are therefore well adapted to adjust to any such changes. On this basis, and as the combined area of the turbidity plumes is small compared with the area available to seals within the SAC, no in combination effects are predicted.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

- 198 - 6.9.4.6 Anadromous fish

Due to reinstatement of the outfall channel, resuspension of sediments by the proposed PPS discharge will be very localised. There will be no overlap of this turbidity plume with: ƒ turbidity plumes from construction and dredging at Martello Quays, as these activities will be contained within a piled coffer dam; ƒ effects of mussel cultivation and dredging at Angle Bay, as the appropriate assessment concluded that effects would be short lived (30-60 minute) and comparable in magnitude with natural wind-induced resuspension that typically occurs during the harvesting season(Cefas 2009); ƒ Maintenance dredging 2010, for the next 5 years, has been occurring since before the Pembrokeshire Marine SAC was designated and as such is considered to be part of the background activities by MHPA. The dredging is also not continuous, with MHPA finding that dredged areas are rapidly re-colonised with spoil tipped outside the SAC. ƒ Neyland Marina dredgings disposal, where the monitoring required by the disposal licence shows that there is no evidence of any significant influence of the dredge discharge sediment plume beyond approximately 250m from the discharge location (Cascade 2010); ƒ turbidity plumes arising from discharges containing suspended solids from South Hook LNG treated site run off and from SemLogistics process water, as the emission limits (75mg/l and 70mg/l) are low and within the natural range for Milford Haven, so turbidity plumes, if they occur at all, will be very localised. Turbidity can affect fish by affecting respiration, reducing prey visibility and clogging gills. However, assessment of the potential for plume overlap shows that turbidity arising from the proposed PPS discharge will not create any new barriers to fish migration through in combination effects with turbidity plumes from other PPPs. Therefore, it is not anticipated that there will be any in combination effects on this interest feature relating to turbidity between the proposed PPS discharge and other PPPs giving rise to turbidity in the water column.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

6.9.4.7 Otter

Otter may experience a change in the distribution of prey items due to turbidity plumes at different points in the estuary, which may be beneficial or adverse but, as they are able to detect and exhibit avoidance responses to adverse conditions, take a wide range of prey, including non-fish prey, and are able to switch prey if necessary, they are therefore well adapted to adjust to any such changes. On this basis, and as the combined area of the turbidity plumes is small compared with the area available to otters within both SACs, no in combination effects are predicted.

Conclusion

There will be no adverse effect on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC, from siltation and turbidity as a result of the proposed PPS discharge from W1, in combination with other PPPs.

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6.9.5. Summary of in combination effects of siltation and turbidity

There will be no adverse effects through turbidity or siltation from the PPS discharge from W1, in combination with other PPPs, on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC or the Cleddau Rivers/Afonydd Cleddau SAC. This is because of the very localised nature of the re-suspension, the low sensitivity of key features and biota and the ability, for example, of seals and otters to avoid any areas of high turbidity and because there are no overlaps between the power station and the other PPPs. As a result, it has been concluded that there will be no in-combination effects (whether additive, cumulative or synergistic) arising as a result of the combined operation of the power station and other PPPs.

- 200 - 6.10. Smothering

Smothering relates to the physical covering of benthic habitats (including estuaries, large shallow inlets and bays, mudflats and sandflats not covered by water at low tide and reefs) with silt or with algal mats, so as to interfere with their natural functioning. These are secondary effects of nutrient enrichment (combined with increased temperature), which have been assessed in section 6.7, and turbidity, which is assessed in section 6.9. We therefore consider that further in combination analysis of this hazard is not necessary. There will therefore be no adverse effect through smothering from the PPS discharge from W1, in combination with the other PPPs, on the integrity of the Pembrokeshire Marine/Sir Benfro Forol SAC or the Cleddau Rivers/Afonydd Cleddau SAC. This is because of the very localised scale of any smothering effect and the resilience and adaptability of the habitats and species typical of this environment and because there are no overlaps between the power station and other PPPs. As a result, it has been concluded that there will be no in-combination effects (whether additive, cumulative or synergistic) arising as a result of the combined operation of the power station and other PPPs.

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6.11. Entrainment and impingement

Although the abstraction licence for Pembroke Power Station has already been permitted, CCW have requested further information as to how the protective measures i.e. fish deterrent, recovery and return system have been implemented. The following information confirms that the system conforms to what is currently considered best practice for screening by Environment Agency guidelines. Abstraction 22/61/6/0156 has already been permitted to abstract 40m3/sec. At the time, a difference of opinion occurred with CCW at an early stage, over entrainment and impingement for estuaries/reefs and cave features. It was considered that the objections from CCW were not robust enough, as no other examples had been highlighted where CCW or Natural England had requested protected features to be considered under entrainment / impingement. For example the power stations on the Humber or at Tilbury/Battersea.

We have reconsidered the evidence surrounding the concerns from CCW with regards to phytoplankton. It is still our opinion that the potential effects of the very localised influence of sodium hypochlorite on benthic communities and on planktonic life-stages of benthic fauna would not adversely affect the ecological functioning of the sites. The typical species found within the mixing zone are widely found within the rest of the protected site, outside of the mixing zone. Equally no acute effect is occurring which would adversely effect the site integrity of the protected features. The loss of plankton would not be significant given the size of the site and the natural fecundity of the typical species (the potential reproductive capacity of an individual or population)

The abstraction of 40m3/sec will have a maximum intake velocity of 0.215m/sec, via four drum screens, with 6mm mesh, acoustic fish deterrents and strobe lighting. The intake length is 53m, which will for 95% of the time have an intake velocity, less than or equal to 0.16m/sec. This is in comparison to the natural average tidal velocity of 0.8m/sec.

Two changes have occurred since the original abstraction licence, the extent of the mapped features shown has increased, specifically in figure 1.3 Estuaries – where this feature now covers the entire Milford Haven. Also figure 1.7, where additional reef features have been identified throughout Milford Haven.

The abstraction licence considered a number of potential hazards, which can be summarised as:-

ƒ Freshwater flow – which was within natural velocities, therefore no alone Adverse effect on site integrity (AEOSI); ƒ Salinity regime – no process contribution of freshwater, just re-distribution – therefore no AEOSI; ƒ Habitat loss - discharge velocity of 0.65m/sec is less than the natural tidal velocity – therefore no alone AEOSI; ƒ It was noted that habitat loss will occur for estuaries, due to the fish deterrents resulting in otters not using ~1000m2 of foraging area (the area in front of the intake structure), however as they are opportunistic feeders with large territories this is considered alone to be no AEOSI.

- 202 - As part of their environmental permit application (Part II, Chapter 8 - Ecological Effects of Cooling Water Abstraction, February 2010) RWE assessed the impact of entrainment on fish. They indicated that: ƒ For herring, the annual entrainment, based on the 2009 Equivalent Adult Value (EAV) estimate based on Pennar Gut figures scaled to 40 m3/s abstraction, is 0.03% of CCW's estimated stock size [the EAV estimate is 5.2 x 10^3 adult equivalents]. CCW's estimated stock size is 16 million; ƒ The annual EAV estimate for bass entrainment is 0.02 adult equivalents; ƒ For plaice the same figure is 65 adult equivalents; ƒ For Goby, the most prevalent species caught in the ichthyoplankton surveys, it is estimated that the annual entrainment rate is 1.8% of the total Milford Haven population. These figures relating to entrainment need to be considered in context - they assume that concentrations of larvae entering the intake will be the same as those in the abstraction zone of the water body, which other power station studies suggest may be a cautious approach as there would appear to be some capacity for avoidance; they take no account of year-on-year natural variations in concentrations; and, they take no account of density-dependent population regulation factors that would tend to reduce any impact of losses in early life stages (ref email RWE to EAW 18 October 2011 The assumption of 100% mortality of all entrained organisms is not supported in the latest EA guidelines on new generation nuclear power stations or by the results of the entrainment survival studies based on the Sizewell B cooling water circuit model which indicated that, depending on species and lifestage, a considerable proportion may pass unharmed back to the sea96. Cefas are due to carry out some research using a new build Entrainment Mimic Unit (EMU) at their Lowestoft Laboratories which will further inform this position. The measures to protect fish and marine mammals are discussed further in the following sections.

6.11.1 Fish Deterrent System (FDS)

For a fish deterrent system to be effective two criteria must be met; the deterrent must be within the sensory range of the target species and the flow velocities where the fish encounter the deterrent, must be sufficiently low to enable fish to escape. The fish deterrent system comprises of two parts; an Acoustic Fish Deterrent (AFD) and a strobe light. Both systems serve to deter fish from entering the cooling water through providing an auditory or visual stimuli designed to elicit a behavioural response. The AFD creates a sound barrier through emission of a sound signal of the 30-100Hz hearing band that is audible to the target fish species. The effectiveness of the system depends mainly on the hearing sensitivity of individual species. For demersal fish, such as salmonids, bass and cod species, AFD deflection efficiency is between 50-70%, while deflection efficiency for pelagic species, such as herring and shad, are around 80-95% (Turnpenny et. al., 2010). The potential impacts of noise from the AFD on aquatic mammals has been assessed in a previous application at Hartlepool nuclear power station. Here a study of common and grey seals was undertaken in a nature reserve adjacent to the power station where an ADF was in operation (Turnpenny et al. 2005). This concluded that the ADF had no detectable effect on the sea numbers or behaviour.

96 Turnpenny and Taylor (2000). An assessment of the effect of Sizewell power stations on fish populations. Hydroecol. Appl 12 (87-134). - 203 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 For fish which lack a swimbladder (typically epibentic species, such as flatfish, gobies) or have less sensitive hearing (such as eels) an AFD has limited value and a deterrent system based solely on an AFD will leave these species vulnerable to impingement or entrainment. For this reason as part of the mitigation, and in line with recommendations in Environment Agency Best Practice Guidelines for Screening (Turnpenny & O’Keefe, 2005), RWE npower have agreed to install a strobe light specifically to reduce potential impacts on eels. The addition of strobe lights should provide additional protection for a wide range of species, including lamprey, but at present this benefit is not quantifiable. RWE npower have calculated the realistic maximum velocity scenario through the line of the AFD/Strobe light deterrent to be 0.215 ms-1. This is below the fish-escape velocity of 0.3 ms-1 recommended as best practice in the ‘Cooling Water Options for the New Generation of Nuclear Power Stations in the UK’ (Turnpenny et. al., 2010).Trialling of the strobes post- commissioning will enable optimal flash rates to be determined.

6.11.2 Fish Recovery & Return System (FRRS)

The fish recovery and return system will recover fish impinged on the drum screens and return them to Pennar Gut via a holding tank. The holding tank will retain fish so that they can be returned around high tide when the velocity towards the intake will be at its minimum. The FRRS used in combination with fish deterrent technologies works well because fish species that have less sensitive hearing are generally more robust and can survive handling on travelling screens. (Turnpenny and O’Keefe, 2005). To maximise survival, the screens will be modified to meet the Best Practice Guidelines for Screening as described by Turnpenny and O’Keefe, 2005. The estimated residual annual kill of impinged fish with the above fish protection technologies fitted, based on extrapolated field data and PISCES estimates, is estimated to amount to 11,860 individuals weighing 113 kg. This is about 16 % by weight of the estimated unmitigated annual catch of impinged fish (i.e. without the fish protection technologies in place) of approximately 79,864 individuals weighing 0.7 tonnes. These figures would be subject to some interannual variability and would not include, for example, any dead or unhealthy fish that would not benefit form the protection systems. Any fish that were killed would be returned as potential food to the ecosystem.

- 204 - Table 6.11 Predicted residual losses due to impingement at Pembroke Power Station with AFD -1 and fish return systems in place and an intake velocity of 0.215 m s . AFD and FRR efficiency data are taken from Turnpenny and O’Keeffe (2005) Species Estimated Annual Fish Return Estimated Annual Loss Impingement for 40 Efficiency for 40 cumecs with AFD cumecs with AFD and Fish Return Number Weight (kg) Number Weight (kg) Bass 1 0 65% 0 0 Sole 4478 45 80% 896 9 Dab 16273 16 80% 3255 3 Plaice 225 9 80% 45 2 Flounder 1835 2 80% 367 0 Salmon and sea 0 0 80% 0 0 trout Grey mullet 87 2 65% 31 1 Cod 9 0 65% 3 0 Pout 4591 27 65% 1606 9 Poor cod 1195 5 65% 418 2 Whiting 6621 159 65% 2317 56 Sprat 0 0 0% 0 0 Herring 0 0 0% 0 0 Sand Smelt 709 4 65% 248 1 Total 36024 269 9186 83 Total all 49 species 47345 367 11860 113 Average Reduction Factor with Fish Return 26% 31% Average Reduction Factor with AFD and Fish Return 15% 16%

To put the fish impingement figures into the context of the SAC, the grey seal (Halichoerus grypus), which feeds on available inshore fish, cephalopods and crustaceans, consumes an estimated 7.5 - 12.5 kg daily (Bonner, 1982), equivalent to 2.7 - 4.6 tonnes per year. On this basis, the loss due to impingement at the proposed Pembroke power station equates to between 8.0% and 13.4% of the annual diet of one grey seal. In terms of annual production in Milford Haven, losses with the AFD and fish return systems in place are estimated to be below 0.2% of the production for the fish species likely to be present Impingement surveys have recorded occasional twaite shad adults An intake with an unscreened inlet fitted with an AFD system, combined with a fish return system fitted to the onshore travelling screens, conform to Environment Agency/CCW Best Practice for a large estuarine plant and would be expected to reduce the impingement rates to 15% of those for an unprotected intake. The screens on the intakes and velocities within the species’ swimming capabilities will ensure that there will be no risk to marine mammals such as otters and grey seals in Pennar Gut.

- 205 - PROTECT - Environmental Permit EA/EPR/DP3333TA/A001 A condition of the abstraction licence requires the developer to develop and carry out a monitoring programme to demonstrate the effectiveness of the proposed system. The full scope of the monitoring programme has been agreed between the Environment Agency and RWE npower and, should the impacts be found to be greater than predicted in the Environmental Statement and supplementary documents, RWE npower will be required to carry out additional mitigation, either to further reduce impacts or provide compensation which could be in the form of Habitat Production Foregone (HPF). The HPF concept addresses lost production through entrainment & impingement to be offset by creating habitat elsewhere to increase production. The proposed monitoring of the performance of the deterrent and fish return system is being used as a benchmark for developing industry standards for post construction monitoring.

Conclusion There will be no adverse effect on the integrity of the Pembrokeshire Marine/ Sir Benfro Forol SAC and Afonydd Cleddau / Cleddau Rivers SAC, from fish impingement and entrainment as a result of the proposed PPS discharge from W1, in combination with other PPP. This is as a result of the following:- ƒ a low cooling water intake velocity in comparison to the natural tidal velocity and the recommended fish escape velocity; ƒ the incorporation of a fish deterrent system that will act as a significant deterrent to fish entering the intake; ƒ for any fish that do enter the intake, a fish recovery and return system that will return many fish to the estuary via a holding tank; ƒ the protective measures conforming to current best practice (EA report: Cooling Water Options for the New Generation of Nuclear Power Stations in the UK, 2010; ƒ the estimated low annual loss of impinged and entrained fish; ƒ the abstraction licence for the Pembroke Power Station requiring a monitoring programme to demonstrate the on-going effectiveness of the protective measures; ƒ the requirement, in the abstraction licence, for further mitigation through enhanced protective measures if required; ƒ the requirement, in the abstraction licence, for RWE to provide future compensation if required. This could be in the form of creating habitat elsewhere.

- 206 - 6.12 In combination conclusion

To fully consider all the potential effects from the proposed Pembroke Power Station, we have included a summary table to cross reference all the effects. Specifically this acts as a summary of the ‘sum of influences acting on a feature from all plans, projects and permission (PPP) in the context of prevailing environmental conditions. We conducted the in combination test in accordance with our guidance (Operating Instruction 183_01 Habitats Directive: taking a new permission, plan or project through the regulations) and went beyond that guidance for trivial effects which had been screened out at the likely significant effect assessment stage. We assessed the power station for likely significant effect in combination with other plans, project and permissions that would be likely to affect the site. In this way we could ascertain the cumulative effect. It is important to note that the scale and duration of the potential effect from the power station on the designated site is far greater than any other plan, project or permission. A matrix was developed, see Table 6.12, that details all the relevant plans, projects and permissions that needed to be considered in combination. We also used the information provided by CCW (In combination matrix CCW 280610) as shown in Appendix 3. Our assessment at the alone stage looked at each feature and habitat, the potential effect and whether there were or were not adverse effects. All such potential effects were reconsidered in combination with the other plans, project and permissions, including trivial effects which had already been considered and screened out in the ‘alone’ assessment and those effects screened out in the likely significant effect assessment both alone and in combination. In this way we have reflected the complexity of the site, that is the spatial distribution of features and habitats, their condition, the conservation objectives and all the potential effects. In conclusion, the EA has assessed the implications for the site in view of the conservation objectives and ascertains that there is no adverse effect alone or in combination, as a result of all the potential effects from the proposed Environmental Permit for Pembroke Power Station, together with other plans, permissions and projects. We are convinced that there will be no adverse effect on the natural range and area covered, the structures and functions necessary for the long term maintenance, or conservation status of the typical species of the habitat features.

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- 208 - Table 6.12 – The sum of the influences acting on a feature from all PPP.

ck ks allow s ts als rged ves tal dows dows fs Potential effects prey

Estuarie Atlantic salt mea Large sh inlets & bays Mud flats & sand fla Ree Sandban Subme sea ca Shore Do Grey se Shad and lam Otters Coas lagoons Document ‘'Appendix 11 EPR NOx 9.3 µg/m³ (12.4% No exceedance of NOx 110µg/m³ (146.7% Feature not sensitive No exceedance of Feature not Feature Feature NOx 3.9 µg/m³ Feature Feature only Fe final revised Apr 11’ – Annex 1 of short-term critical load of short-term to deposition critical load sensitive to not not (5.2% of short-term not sensitive in on ‘110218Appendix11_PEC_final’ benchmark). benchmark). deposition sensitive sensitive benchmark). sensitive freshwater se NOx 0.8µg/m³ (2.7% of NOx 6.1µg/m³ (20.3% to to NOx 0.4µg/m³ (1.3% to environment fre long-term benchmark). of long-term deposition deposition of long-term deposition due to en N deposition benchmark). benchmark). potential du 0.1kg/N/ha/yr (0.3% of N deposition N deposition impacts on po long term benchmark. 0.39kg/N/ha/yr (1.3% of 0.05kg/N/ha/yr prey species im No likely significant long term benchmark. (0.5% of long term pr effect. benchmark. sp SO2 and O3 are not No likely significant close to their critical effect. level – the appropriate critical level for NOx will therefore be 200 μg/m3. NOx PC= 55% of short- term benchmark). So no likely significant effect. Alone - Toxic contamination 4km away. No adverse 0.68% (37.41ha) sea No 0.17% (37.41ha) 1.9% (33.08ha) sea 0.0006% No > No > No No No N effect concluded due to surface. sea surface. surface. (0.24ha) of 10km 3km away feature being outside 0.17% (9.08ha) sea 0.04%(9.08ha) sea 0.36% (6.33ha) reef. away. mixing zone for TRO. bed. bed. sea bed. But only 0.26% of the But only 0.26% of But only 0.26% of the tidal volume the tidal volume tidal volume Alone - Changes in thermal No 9.9% (543.5ha) sea No 2.5% (543.5ha) sea 10.3% (83.1ha) sea 0.2% (85.2ha) No No No Minor No M regime surface. surface. surface. sea surface. change ch 2.5% (135.4ha) sea 0.6% (135.4ha) sea 5.6% (99.9ha) sea 0.01% (4.4ha) may occur oc bed. bed. bed. sea bed. to the pr prey sp However for 95% of However for 95% of However – species in th the time it will be 3.9% the time it will be considerably smaller the lo (212ha) and 1.6% 0.9% (212ha) and > 3deg.C localised vi (89ha) 0.4% (89ha) vicinity of th the di discharge. Alone - Nutrient enrichment No net increase in P due No net increase in P No No net increase in P No net increase in P No net increase No No No No No N to mitigation due to mitigation due to mitigation due to mitigation in P due to mitigation Alone - Habitat loss and No No – only 0.26% of No No – only 0.26% of No – dredging has No No No No No No N physical damage tidal volume affected. tidal volume already occurred. affected. Alone - Siltation and turbidity No No No No No No No No No No No N Alone - Smothering No No No No No No No No No No No N In combination - Toxic Feature is >4km away Mixing zone for TRO No Mixing zone for TRO Unlikely that South Plumes No No No No No N contamination from PPS and the 6 at South Hook LNG at South Hook LNG Hook mixing zone buoyant, no other PPP assessed. No estimated at just over at sea bed is >1ha in will impinge at all on overlap with effect in combination 1ha in area. area. the mudflats and other mixing concluded due to Total area of the >0.1% (22ha) of sandflats interest zones in distance from feature. feature within the feature within PPS feature. Therefore no location of reef mixing zone of South and South hook in combination feature Hook LNG and PPS is mixing zones. Due to effects concluded. therefore no >0.38% (14ha). Due very small area adverse effect

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Potential effects fs sea caves sea caves Shore Dock Grey seals Shad and lamprey Otters Coastal lagoons Estuarie Atlantic salt meadows Large sh inlets & bays Mud flats & sand flats Ree Sandbanks Submerged to very small area concerned no in combination concerned no adverse adverse effect concluded. effect concluded. concluded. In combination - Changes in No SemLogistics may No SemLogistics may Additional maximum The proportion No No Mixing zone N thermal regime overlap with the overlap with the extent of mixing zone of the thermal only mixing zone for the mixing zone for the at sea surface from mixing zones at overlaps proposed PPS thermal proposed PPS other thermal the sea bed with discharge and the thermal discharge discharges would from each of Semlogistics Murco and Chevron and the Murco and mean additional the discharges at sea refineries at the sea Chevron refineries at 0.52% (MARLIN) of that could act in surface. surface, increasing the sea surface, feature exposed to a combination is: area of feature increasing the area temp rise above 2°C. No adverse exposed to a temp of feature exposed Murco – 50% effect on rise above 2°C by to a temp rise above Due to the scale and Chevron = 10% site integrity 2.3%. 2°C by 0.5%. frequency of the Semlogistics = concluded plume, concluded no 80% as in This is a precautionary This is a adverse effect on site combination result, as for 95% of precautionary result, integrity. This equates to there is no the time the area will as for 95% of the 0.4% of total barrier to be considerably less. time the area will be reef habitat fish considerably less. within SAC migration Due to the scale and exposed to a from the frequency of the Due to the scale and temp rise thermal plume concluded no frequency of the above2°C. plumes. adverse effect in plume no adverse combination on site effect in combination Determined no integrity. on the site integrity. adverse effect on site integrity from exposure of this magnitude. In combination - Nutrient No net increase due to No net increase due to No No net increase due No net increase due No net increase No No No No No N enrichment mitigation mitigation to mitigation to mitigation due to mitigation In combination - Habitat loss No Erosion effects very No Erosion effects very Erosion effects very Erosion effects No No No N No N and physical damage localised around PPS localised around localised around very localised outfall. No in PPS outfall. No in PPS outfall. No in around PPS combination effects combination effects combination effects outfall. No in with other outfalls with other outfalls with other outfalls combination therefore no adverse therefore no adverse therefore no adverse effects with effect on site integrity effect on site effect on site integrity other outfalls concluded. integrity concluded.. concluded.. therefore no adverse effect on site integrity concluded. No Re-suspension very No Re-suspension very Re-suspension very Re-suspension No No No N Re- N localised therefore localised therefore localised therefore very localised suspension due to small scale no due to small scale due to small scale no therefore due to very adverse effect on site no adverse effect on adverse effect on site small scale no localised integrity in site integrity in integrity in adverse effect therefore combination combination combination on site integrity due to small concluded. concluded. concluded. in combination scale no concluded. adverse effect on site integrity In combination - Siltation and in turbidity combination - 210 - Potential effects prey Sandbanks Sandbanks Submerged sea caves Shore Dock Grey seals Shad and lam Otters Coastal lagoons Estuaries Atlantic salt meadows Large shallow inlets & bays Mud flats & sand flats Reefs concluded. In combination - Smothering No No No No No No No No No No No N No 0.2% of the production No 0.2% of the 0.2% of the No No No No No No N for the fish species production for the production for the In combination - Entrainment likely to be present fish species likely to fish species likely to and impingement be present be present

- 211 - 6.12.1 Cross comparison of potential effects on features

Table 6.12 shows a summary of all the possible effects from the proposed Pembroke Power Station. The following information summarises our findings from this appropriate assessment on each of the interest features. It considers the in combination effects from the different operational aspects of the Pembroke Power Station application and in combination with other plans, projects and permissions. It also considers the concerns expressed by CCW.

Coastal habitats sensitive to abstraction • Coastal lagoons (FCS status - Favourable maintained 2006)

EA conclusion Due to the locations of the Coastal Lagoon feature, which occur in four discrete locations within the Pembrokeshire Marine SAC, see Figure 4.1, it is clear that the potential for adverse effect is limited. Our analysis of the proposed emissions, shown in Table 6.12, indicates that the possibility of an effect alone and in combination is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall and those of other permissions that could act in combination with PPS.

Estuarine and intertidal habitats • Estuaries (FCS status – Un-favourable declining 2006)

EA conclusion The outfall from the proposed Pembroke Power Station discharges directly into the estuaries feature. Using the outputs of modelling, our assessment indicates that, even though this feature is currently in un-favourable conservation status, the total area of this feature exposed to the possibility of adverse effect (i.e. within the mixing zone) is small enough and over a short enough duration to not constitute an adverse effect on site integrity alone or when considered in combination with potential impacts from other permissions, plans and projects.

• Atlantic salt meadows (Glauco-Puccinellietalia maritimae) (FCS status – Un- favourable unclassified 2006)

EA conclusion The potential for adverse effects on the Atlantic salt meadow feature come mainly from smothering as a result of sediment erosion and deposition and increased levels of organic carbon leading to smothering and oxygen depletion both in the sediment and the water column. Our assessment concludes that there will be no adverse effect on this feature as a result of the localised scale of the impacts, the dynamic nature of the receiving environment, the dilution of the effluent plume and the location of the discharge point in relation to the feature.

• Large shallow inlets and bays (FCS status – Un-favourable declining 2006)

EA conclusion The ria part of this feature is wholly encompassed in the estuaries habitat and there is also some overlap with mudflats and sandflats feature. Our assessment indicates that, even though this feature is currently in un-favourable conservation status, the total area of this feature exposed to the possibility of adverse effect (i.e. within the mixing zone) is small enough and over a short enough duration to not constitute an adverse effect on site integrity alone or when considered in combination with potential impacts from other permissions, plans and projects.

- 212 - • Mudflats and sandflats not covered by seawater at low tide (FCS status – Un- favourable declining 2006)

EA conclusion Overall, it is expected the biotopes associated with this feature would undergo a decrease in species richness in the immediate vicinity of the outfall. However it is not considered that this decrease would affect the functioning of the ecosystem because the impact is localised. Although the conservation status of mudflats and sandflats not covered by seawater at low tide is unfavourable-declining, the small scale of the mixing zone in comparison to the site, leads the EA to ascertain that there is no adverse effect on the natural range and area covered, the structures and functions necessary for the long term maintenance, or conservation status of the typical species of mudflats and sandflats.

Submerged marine habitats

• Reefs (FCS status – Un-favourable no change 2006)

EA conclusion Given the very small scale of potential effect, it is ascertained that there is no adverse effect from the proposed Pembroke Power Station outfall alone or in combination with other plans, permissions and projects on the natural range and area covered, the structures and functions necessary for its long-term maintenance, or conservation status of the typical reef species.

• Sandbanks which are slightly covered by seawater all the time (FCS status – Un- favourable no change 2006)

EA conclusion Due to the location of this feature, some 10km from the proposed Pembroke Power Station outfall, see Figure 4.7, it is clear that the potential for adverse effect is limited. Our analysis of the proposed emissions, shown in Table 6.12, clearly indicates that the possibility of an effect alone and in combination is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall and those of other permissions that could act in combination with PPS.

• Submerged or partially submerged sea caves (FCS status - Favourable maintained 2006)

EA conclusion Due to the location of this feature in relation to the proposed Pembroke Power Station outfall, see Figure 4.8, it is clear that the potential for adverse effect is limited. Our analysis of the proposed emissions, shown in Table 6.12, clearly indicates that the possibility of an effect alone and in combination is negligible due to dilution factors as a result of the distance of the feature from the proposed Pembroke Power Station outfall and those of other permissions that could act in combination with PPS.

Coastal plants • Shore Dock (FCS status - Favourable maintained 2006)

EA conclusion The likely significant effect test (Stage2) - 'Appendix 11 EPR final revised Apr 11’ document concluded no likely significant effect on this feature as a result of the proposed Pembroke Power Station environmental permit.

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Marine mammals • Grey seals (FCS status - Favourable maintained 2006)

EA conclusion Grey seals are able to detect and exhibit avoidance responses to adverse conditions and are well adapted to adjust to any changes in the balance of populations within their prey species. This combined with the fact that they only spend a small amount of time in the estuary and that TRO does not tend to bioaccumulate in their food chain means that the risk of direct or indirect effects on seals from the proposed Pembroke Power Station discharge is very low. On this basis, and as the combined area of the mixing zones of all the effluents is small compared with the area available to seals within the SAC, no in combination effects on the conservation status of this interest feature are predicted.

Anadromous fish • Allis shad (Alosa alosa) (FCS status - Unknown 2006) • Twaite shad (Alosa falax) (FCS status - Unknown 2006) • Sea lamprey (Petromyzon marinus) (FCS status – Un-favourable declining 2006) • River lamprey (Lampetra fluviatilis) (FCS status – Un-favourable no change 2006)

EA conclusion The key requirement for anadromous fish in estuaries is that a passage is available at all times that adults or juveniles wish to migrate which does not entail exposure to hazards that might compromise their breeding ability or the ability of the juveniles to return to the sea or in the case of river lamprey often to suitable estuarine habitat. As there will be no barriers to fish migration established as a result of discharges in the proposed Pembroke Power Station cooling water discharge in combination with other discharges, and as the potential adverse effects on fish of the abstraction licence will be addressed through design of a fish return system, it is our conclusion that there will be no in combination effects on the anadromous fish interest features between the Pembroke Power Station discharge and the Pembroke Power Station cooling water abstraction or with other plans, projects or permissions that could act in combination.

Mammals of riverine habitats • Otters (Lutra lutra) (FCS status - Favourable maintained 2006)

EA conclusion Otter may experience a change in the balance and distribution of prey items as a result of the proposed Pembroke Power Station, which may be beneficial or adverse but, as they are able to detect and exhibit avoidance responses to adverse conditions, take a wide range of prey, including non-fish prey, and are able to switch prey if necessary, they are therefore well adapted to adjust to any such changes. On this basis, and as the combined area of the mixing zones associated with the proposed outfall alone and in combination with other plans, projects and permissions is small compared with the area available to otters within both SACs, no alone or in combination effects are predicted.

- 214 - Sum of all influences

After taking all relevant factors into consideration and subjecting our assumptions and decisions to internal and external peer review, as well as consultation with Cefas and CCW, we the competent authority for this environmental permit, have concluded that:- ƒ changes to the physical nature of the habitat due to the existing abstraction and proposed discharge would be within the natural dynamics of the tidal system. There would not be a measurable reduction on the extent or structure of the habitat. ƒ the addition or redistribution of nutrients has the potential to have adverse effects. However the nutrient mitigation discussed in section 5.3 counteracts this with a net decrease in the amount of amount of plant nutrients (biologically available nitrogen and phosphorus that causes excessive algal growth) entering the system. This will result in less growth of nuisance algae, leading to improvement in the eel grass beds (a typical feature of the Pembrokeshire Marine SAC ƒ the volume and dynamics of the tidal currents will very quickly mix, dilute and dissipate any residual toxic effect from the discharge. Localised changes in species living with the sediments would not affect the overall extent of their distribution and ability to grow, reproduce and migrate; ƒ the effect of the thermal plume (and its cumulative effect on prevailing conditions such as nutrient levels and toxic chemicals) would not significantly affect the ecology of the water column; ƒ the ambient diurnal temperature range for inter-tidal habitats far exceeds the effects of the predicted thermal plume, so other than very localised effects near point of discharge, there would be no significant impact on the biological communities living in the sediment because they are well adapted to living in such variable conditions; ƒ loss of fish through entrainment would not affect their overall populations and the loss of plankton would not be significant given the size of the site and the natural fecundity of the typical species (the potential reproductive capacity of an individual or population).

On this basis, we consider that the character and dynamics of the designated sites and the natural resilience of the habitats and species in the ecosystem (e.g. the capacity of species to adapt to localised impacts, replenish their populations) would be able to compensate for the predicted localised physical, chemical and temperature changes, which consequently will not adversely affect the structure and ecological functioning of the site. The detailed evidence and reasoning for these conclusions is included in the technical sections (chapters 4-6) of the appropriate assessment. The Environment Agency, as an environmental regulator has acted reasonably so as to reduce any scientific doubt in its conclusions. We have listened to the advice of the consultees and delivered a precautionary assessment, using the best available information. We are convinced that we have met the site integrity test and that the proposed Environmental Permit, with conditions and restrictions imposed, will not have an adverse effect on Pembrokeshire Marine / Sir Benfro Forol Special Area of Conservation (SAC) and Afonydd Cleddau / Cleddau Rivers SAC.

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Appendices (supplied separately to this document)

Appendix 1 Alone Appropriate assessment record: cross referencing ‘elements of favourable conservation status’. This refers to the spreadsheet in which each of the potential hazards from the proposed environmental permit, that are likely to have a significant effect, are assessed against each of the elements of favourable conservation status for the designated features. Where one of more of the elements of favourable conservation status is not met, these are discussed in Section 5 Appendix 2 Log of requests for more information from the applicant. Appendix 3 In-combination matrix provided by CCW 280610.

Annex

PPS AA Annex I Marine Fish Nursery Function in the Inner Milford Haven PPS Annex Ia A map of Cleddau WFD Estuary fish sites 2000-2009 PPS Annex II RWE Pembroke – Organohalogen assessment updated PPS Annex III CCW letters

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Can it be decided that the PPP will not adversely affect the integrity of the European site(s)?

Yes. It is anticipated that localised effects will occur in the vicinity of the proposed Pembroke Power Station cooling water discharge, but those effects will not affect the ecological functioning of the SAC or compromise the presence of typical species within the SAC. The Environment Agency has assessed the implications for the site in view of the conservation objectives and ascertained that alone and in combination there will be no adverse effect on site integrity on Pembrokeshire Marine / Sir Benfro Forol and Afonydd Cleddau / Cleddau Rivers SAC.

Name of officer undertaking appropriate assessment:

Signed: Date 3 November 2011

Endorsed by: (team leader, if appropriate)

Signed: Date 8 November 2011

CCW comments on appropriate assessment Is there agreement with the conclusion? Yes/No (Please provide summary and explanation for answer given)

Name of: (CCW local team manager)

Signed: Date

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Part B: Final appropriate assessment record

Description: Pembroke Power Station Environmental Permit. NGR: SM92700 02600. Date of appropriate assessment: 8 November 2011

Final statement: This is a record of the appropriate assessment required by Regulation 61 of the Conservation of Habitats and Species Regulations 2010 (SI No. 2010/490), undertaken by the Environment Agency in respect of the above plan/project/permission (PPP), in accordance with the Habitats Directive (Council Directive 92/43/EEC) Having considered that the PPP would be likely to have a significant effect on Pembrokeshire Marine / Sir Benfro Forol SAC and Cleddau Rivers / Afonydd Cleddau SAC and that the PPP was not directly connected with or necessary to the management of the site for nature conservation, an appropriate assessment has been undertaken of the implications of the proposal in view of the site’s conservation objectives. CCW were consulted under Regulation 61(3) on 30th March 2011 and their representations, to which the Environment Agency has had regard, are attached in Annex III. The conclusions of this appropriate assessment are not in accordance with the advice and recommendations of CCW. The applicant was required to submit further information reasonably necessary for this assessment on a number of occasions. Details of this can be found on our public register. The site’s nature conservation objectives have been taken into account, including consideration of the information supplied by CCW. The likely effects of the proposal on the international nature conservation interests for which the site was classified or designated are summarised within this appropriate assessment. The assessment has concluded that: The imposition of conditions and/or restrictions on the way the project is to be carried out in the Environmental Permit for the power station and listed within the decision document ‘‘Determination of an Application for an Environmental Permit under the Environmental Permitting (England & Wales) Regulations 2010: Consultation on our decision document recording our decision-making process’, would avoid adverse effects on the integrity of the site so that a conclusion of no adverse effect on site integrity can be reached.

Name of relevant Environment Agency manager: Signed: Date

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