An Assessment Under the Conservation of Habitats and Species Regulations (2017)

An Assessment under the Conservation of Habitats and Species Regulations (2017)

in respect of

Application 6/2018/0567

Installation of a new Power Generation Plant, incorporating 2 no. 12MW gas engines within an engine hall; selective catalytic reduction units; waste heat recovery units incorporated within 2 no. 15.2M exhaust stacks and associated works at Wytch Farm Gathering Station. Decommissioning of 2 no. existing gas turbines and waste heat recovery unit.

At Wytch Farm Oilfield, nr Corfe Castle, Dorset

Dr Annabel King Senior Ecologist, Dorset County Council

January 2019

Contents Page

1.0 Introduction . . . . . 3

2.0 Provision of Sufficient Information . . . . . 4

3.0 Summary of Proposal and Site Location . . . . 5

4.0 European Sites and Summary Information . . . . 7

5.0 Screening Assessment to Determine Likely Significant Effect . . 10

6.0 Appropriate Assessment ...... 12

7.0 In-combination Effects ...... 16

8.0 Conclusion and Reg 63(5), the Integrity Test . . . . 16

1.0 Introduction

This report assesses the power generation proposals at Perenco’s Wytch Farm oilfield nr. Corfe Castle under the Conservation of Habitats and Species Regulations (2017). These Regulations transpose into UK law the EU Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the Habitats Directive).

Article 3 of the Habitats Directive establishes the need to set up a ‘coherent European ecological network of special areas of conservation (SAC’s), under the title of Natura 2000’. These include European Marine Sites (where part of the site is below the highwater mark) and European Offshore Marine Sites (where the whole of the site is offshore). Article 3 also states that this network should include Special Protection Areas designated under Directive 79/409/EEC, the Birds Directive. National planning policy (National Planning Policy Framework 2018, para 176) states that listed or proposed Ramsar sites (those established under the Convention on Wetlands of International Importance, in Ramsar, Iran, 1971) should also receive the same protection as Natura 2000 sites, as should possible SAC’s and potential SPAs. Regulation 8 of the Habitats Regulations also stipulates that pSACs and pSPAs should receive the same protection as Natura 2000 sites. For the purposes of this document all these sites will be referred to collectively as European sites.

Article 6, paragraph 3 of the Habitats Directive establishes the need to assess plans and projects individually or in combination for Likely Significant Effect on Natura 2000 sites and goes on to state that if this is the case the plan or project ‘must be subject to Appropriate Assessment of its implications for the site in view of the site’s conservation objectives’.

In other words, the assessment of plans or projects is divided into two stages: an initial ‘screening assessment’ of whether the plan or project will result in Likely Significant Effect on the relevant European sites, and, if needed, a second ‘Appropriate Assessment’ of whether the plan or project will have an adverse effect on the integrity of the relevant European sites. Article 6, paragraph 4 deals with those rare situations where there are imperative reasons of overriding public interest (IROPI cases) which result in the conclusion that a plan or project should be carried out despite identification of adverse effect on the integrity of the European sites. It stipulates that if this is the case then compensatory measures must be taken to ensure that the overall coherence of the Natura 2000 network is protected.

Paragraphs 3 and 4 of Article 6 are transposed into UK law via Regulations 63 and 64 of the Conservation of Habitats and Species Regulations, 2017. Regulation 63 states:

(1) A competent authority, before deciding to undertake, or give any consent, permission or other authorisation for, a plan or project which— (a) is likely to have a significant effect on a European site or a European offshore marine site (either alone or in combination with other plans or projects), and (b) is not directly connected with or necessary to the management of that site, must make an appropriate assessment of the implications of the plan or project for that site in view of that site’s conservation objectives. (2) A person applying for any such consent, permission or other authorisation must provide such information as the competent authority may reasonably

require for the purposes of the assessment or to enable it to determine whether an appropriate assessment is required. (3) The competent authority must for the purposes of the assessment consult the appropriate nature conservation body and have regard to any representations made by that body within such reasonable time as the authority specifies. (4) It must also, if it considers it appropriate, take the opinion of the general public, and if it does so, it must take such steps for that purpose as it considers appropriate. (5) In the light of the conclusions of the assessment, and subject to regulation 64, the competent authority may agree to the plan or project only after having ascertained that it will not adversely affect the integrity of the European site or the European offshore marine site (as the case may be)

It can be seen that Regulation 63 imposes several stages of tests and duties on the competent authority as part of the assessment process (including the concluding ‘integrity test’ as part of Reg 63(5)). Further sections of this assessment consider the initial screening of the proposals and, if necessary, the Appropriate Assessment (Reg 63(1)). However, for the purposes of this assessment:

• It is concluded that the proposed development is neither directly connected with or necessary to the management of any European sites (Reg 63(1)(b)). • The applicant has supplied sufficient information to the planning authority (as required under Reg 63(2)) to enable a determination of whether an appropriate assessment is required, and to enable an Appropriate Assessment if required. • The competent authority (Dorset County Council) has consulted Natural England about the proposals and the content of this assessment (as required under Reg 63(3)).

Regulation 63(1)(a), consideration of ‘in combination’ effects will be discussed as part of the assessment process.

Regulation 63(5), known as the ‘integrity test’ will be considered in the conclusion to this report.

Previous case law (Hart District Council v Sect of State for Communities and Local Government: CO/7623/2007)) concluded that proposed mitigation could be considered at the initial screening stage of a Habitats Regs Assessment, while screening for Likely Significant Effects. However, subsequent case law (People Over Wind, Peter Sweetman v Coillte Teoranta: C-323/17) has now established that mitigation should only be included as part of an Appropriate Assessment.

2.0 Provision of Sufficient Information

The following documents have been referred to, to enable the preparation of this report:

• Wytch Farm Power Generation Project: Planning Support Statement, September 18 • Wytch Farm Power Generation Project Environmental Statement: Non- Technical Summary, September 2018

• Wytch Farm Power Generation Project Environmental Statement, in particular:

o Chapter 6 – providing a detailed examination of biodiversity interests on site and the impact of the proposals on these o Chapter 7 – providing a detailed examination of air quality and the construction dust assessment o Figures 7.3 – 7.18

Meetings with DCC Planning, Natural England, Perenco and Nicholas Pearson Associates were attended throughout 2018.

3.0 Summary of Proposal and Site Description

Perenco’s Wytch Farm oilfield is located on the Isle of Purbeck in Dorset. Although the offices are based at Furzebrook, south of Stoborough, the proposed development site is at the Gathering Station for the Wytch Farm, Wareham and Kimmeridge oilfields, 2.7km north east of Corfe Castle village, SY97388478, (see Plan 1).

Plan 1: Location of proposed Power Generation Plant at Wytch Farm Gathering Station with European sites shown in blue (Ramsar), orange (SPA) and purple (SAC) hatching.

The Gathering Station covers an area of approximately 12.4 hectares and is essentially flat at an elevation of approximately 13m above ordnance datum. It is within an area with a low risk of flooding from groundwater, rivers or the sea. The Gathering Station is situated within an area of conifer plantation that provides an effective visual screen.

The proposed Power Generation Plant would be located adjacent to the southern operational boundary of the South Site Gathering Station in an area that does not currently have any plant within it (see Plan 2). The total planning application area is approximately 0.63 hectares.

Plan 2: Location of Power Generation Project at Wytch Farm Gathering Station,

The development is required in order to generate more electricity on-site. This would reduce the significant ongoing costs associated with importing electricity and have additional benefits in terms of greater energy efficiency and self-sufficiency. The existing Gas Turbines are approximately 30% efficient and do not currently represent best practice for onsite power generation. The Gas Turbines are also ageing and becoming less reliable.

Following detailed consideration of the above, Perenco propose to generate more electricity within the South Site of the Gathering Station through the installation of two new Gas Engines located within a building, with two 15.2m exhaust stacks. The proposals would include decommissioning the existing Gas Turbines and Waste Heat Recovery Unit on the South Site Gathering Station and replacing them with a new, more efficient, 24-megawatt Gas Engine Power Generation Plant, comprising two Gas Engines and two Waste Heat Recovery Units. The two existing flares would be retained.

The two Gas Engines would be housed within a building (the Engine Hall) approximately 32m x 17m and 12.34m high. Two proposed exhaust stacks would extend 15.2m above the existing grade level. They would be located external to the building, as would the radiator cooling fan array. Waste Heat Recovery Units are incorporated into the exhaust stacks and a radiator cooling fan array would be located on the roof of the building, surrounded by a louvered screen. Two ventilation outlets from the Engine Hall would protrude from the top of the building up to 13.5m.

Associated infrastructure includes a new grid gas connection; an extension to an existing pipe-rack carrying pipes and cabling; and high-voltage cabling buried within the ground to connect to the existing high-voltage sub-station.

4.0 European Sites and Summary information

The Gathering Station Power Generation site is in proximity to:

• Dorset Heaths SAC, • Dorset Heaths (Purbeck and Wareham) and Studland Dunes SAC, • Dorset Heathlands SPA, • Poole Harbour SPA, • Dorset Heathlands Ramsar, • Poole Harbour Ramsar. • Isle of Portland to Studland Cliffs SAC and • St Albans Head to Durlston Head SAC

As discussed in Chapter 6 of the Environmental Statement, the scale of works, prevailing south westerly wind and the fact that the main issue associated with the works is emissions and nutrient deposition, allows the Isle of Portland to Studland Cliffs SAC and St Albans Head to Durlston Head SAC to be scoped out of this report.

Poole Harbour SPA and Ramsar and the Dorset Heaths SAC are also excluded from further consideration in this report. This is because previous assessment work (the Appropriate Assessment carried out alongside the 2012 Sect 73 PA2 application to extend the life of the Wytch Farm, Wareham and Kimmeridge oilfields) concluded that there would not be any significant impacts on these sites from operation of the Wytch Farm oilfield and air quality modelling carried out for the current application confirms this conclusion.

The remaining European sites (Dorset Heathlands SPA and Ramsar and the Dorset Heaths (Purbeck & Wareham) and Studland Dunes SAC) are scoped in to this assessment and are listed below along with their qualifying features and conservation objectives.

These European sites are underpinned by the following SSSI’s:

• Rempstone Heaths SSSI • Brenscombe Heath SSSI • Thrashers Heath SSSI • Hartland Moor SSSI • Arne SSSI • Blue Pool and Norden Heaths SSSI

However, as explained below in Section 6.2 below, only Rempstone Heaths SSSI is considered to be within the Zone of Influence, based on the air quality assessment criteria.

Information on the conservation status of Rempstone Heath SSSI (gained from condition assessment monitoring) is summarised and used below to form a view on the condition of the European sites. This is important as Article 3(1) of the Habitats Directive (1992) requires Natura 2000 sites to be maintained or restored to 7 favourable conservation status and this is ascertained through use of the condition assessment monitoring of the underlying SSSI.

Table 1 lists the relevant European sites and their qualifying features (Habs Directive Annex 1 habitats or Annex 2 species and Birds Directive Annex 1 birds). Table 2 lists the European sites and their conservation objectives. Table 3 gives the summary condition assessment of the relevant underlying SSSI.

Table 1: The relevant European sites and their qualifying features.

European Sites Qualifying habitats and species (inte rest features) Dorset Heaths • Alkaline fens. (calcium-rich springwater-fed fens) (Purbeck and • Atlantic decalcified fixed dunes (Calluno-Ulicetea). Wareham) and (Coastal dune heathland) Studland Dunes SAC • Bog woodland (UK0030038 ) Annex 1 • Calcareous fens with Cladium mariscus and species Habs Directive habitats and Annex 2 Habs Directive of the Caricion davallianae. (Calcium-rich fen species dominated by great fen sedge (saw sedge)) • Depressions on peat substrates of the Rhynchosporion • Embryonic shifting dunes • European dry heaths • Humid dune slacks • Molinia meadows on calcareous, peaty or clayey-silt- laden soils (Molinion caeruleae). (Purple moor-grass meadows) • Northern Atlantic wet heaths with Erica tetralix . (Wet heathland with cross-leaved heath) • Old acidophilous oak woods with Quercus robur on sandy plains. (Dry oak-dominated woodland) • Oligotrophic waters containing very few minerals of sandy plains: Littorelletalia uniflorae. (Nutrient-poor shallow waters with aquatic vegetation on sandy plains) • Shifting dunes along the shoreline with Ammophila arenaria (white dunes). (Shifting dunes with marram) • Temperate Atlantic wet heaths with Erica ciliaris and Erica tetralix . (Wet heathland with Dorset heath and cross-leaved heath) • Southern damselfly Coenagrion mercuriale • Great crested newt Triturus cristatus

Dorset Heathlands Dartford warbler – Sylvia undata SPA (UK9010101) Nightjar – Caprimulgus europaeus Annex 1 Birds Directive Woodlark – Lullula arborea Species Hen Harrier – Circus cyaneus Merlin – Falco columbarius Dorset Heathlands • Ramsar criterion 1: Contains particularly good Ramsar Site examples of (i) northern Atlantic wet heaths with (UK11021) cross-leaved heath Erica tetralix and (ii) acid mire with Rhynchosporion . Contains largest example in Britain of southern Atlantic wet heaths with Dorset heath Erica ciliaris and cross -leaved heath Erica

tetralix . • Ramsar criterion 2: Supports 1 nationally rare and 13 nationally scarce wetland plant species, and at least 28 nationally rare wetland invertebrate species. • Ramsar criterion 3: Has a high species richness and high ecological diversity of wetland habitat types and transitions, and lies in one of the most biologically- rich wetland areas of lowland Britain, being continuous with three other Ramsar sites: Poole Harbour, Avon Valley and The New Forest.

Table 2: The relevant European sites and their conservation objectives

European Sites Conservation objectives Dorset Heaths (Purbeck Ensure that the integrity of the site is maintained or and Wareham) and restored as appropriate, and ensure that the site Studland Dunes SAC contributes to achieving the Favourable Conservation Status of its Qualifying Features, by maintaining or restoring; • The extent and distribution of qualifying natural habitats and habitats of qualifying species • The structure and function (including typical species) of qualifying natural habitats • The structure and function of the habitats of qualifying species • The supporting processes on which qualifying natural habitats and the habitats of qualifying species rely • The populations of qualifying species, and, • The distribution of qualifying species within the site. Dorset Heathlands SPA Ensure that the integrity of the site is maintained or restored as appropriate, and ensure that the site contributes to achieving the aims of the Wild Birds Directive, by maintaining or restoring: • The extent and distribution of the habitats of the qualifying features • The structure and function of the habitats of the qualifying features • The supporting processes on which the habitats of the qualifying features rely • The population of each of the qualifying features, and • The distribution of the qualifying features within the site.

Table 3: Condition Assessment of the relevant SSSI heathlands

SSSI Condition Assessment Rempstone Heath SSSI 84.22% in favourable or unfavourable/recovering condition (143.14ha of 169.97ha) 9

5.0 Screening Assessment to Determine Likely Significant Effect

Regulation 63(1)(a) requires the competent authority to consider whether the development would have a Likely Significant Effect on the features for which the relevant European sites are designated, either alone or in combination with other projects. Generally, Natural England considers that a development proposal would have a likely significant effect if it:

• Reduces the area of the site or habitat; • Causes direct or indirect change to the physical quality of the environment (including the hydrology) or habitat within the site; or • Causes direct damage to the size, characteristics or reproductive ability of populations on the site.

Additionally, the Environmental Statement summarises the scoping exercise which was undertaken as part of the application and concludes that the initial scope of assessment should include:

• During construction: o Noise from construction activities, plant and vehicles o Dust • During operation: o Air quality: emissions of Nitrogen Oxides (NOx) and ammonia and nutrient nitrogen and acid deposition o Noise from the proposed power generation plant.

Applying the Natural England criteria and considering the results of the scoping study summarised in the Environmental Statement, the screening assessment considers the following impacts:

• Direct loss of habitat from land take • Disturbance to species which are interest features of the European sites from noise, during construction and operational phases. • Indirect loss of habitat from dust smothering vegetation or gradually affecting vegetation composition, during construction and operational phases. • Indirect loss or degradation of habitat from gaseous emissions and deposition, specifically emissions of Nitrogen Oxides (NOx) and ammonia and nutrient nitrogen and acid deposition.

5.1 Direct loss of habitat from land take

The proposed works would all be carried out within the confines of the existing gathering station site and the access road running to the site from Norden at Corfe Castle. Therefore, it is concluded that the construction and operation of the power generation project would not lead to a Likely Significant Effect on the European sites from direct loss of habitat.

5.2 Disturbance to species which are interest features of the European sites from noise, during construction and operational phases

The only species considered in this section is Nightjar, as the other qualifying species of the relevant European sites (woodlark, Dartford warbler) which could potentially be affected are not known to inhabit the area around the Gathering Station. Although Merlin and Hen Harrier are also listed as qualifying species, they can be scoped out

10 as it is stated on the Air Pollution Information System (APIS) website that there would be no negative impacts on these species as a result of air quality impacts due to their broad habitat range.

However, the proposed works within the Wytch Farm Gathering Station could potentially generate levels of noise which may affect Nightjar, an interest feature of the Dorset Heathlands SPA which is adjacent to the Gathering Station. This may affect breeding success within the vicinity of the works or deter Nightjar from using (inhabiting or breeding) those areas adjacent to the works.

For this reason it is concluded that the construction and operation of the power generation project could result in a Likely Significant Effect on Nightjar as a result of disturbance from noise during construction and operation. These effects are discussed further in the Appropriate Assessment below.

5.3 Indirect loss of habitat from dust smothering vegetation or gradually affecting vegetation composition, during construction and operational phases

A construction dust assessment was carried out, considering the potential for impacts within 50m of the site boundary or within 50m of roads used by construction vehicles for ecological receptors. The results of this assessment are presented in Chapter 7 of the Environmental Statement.

The assessment concluded that there would be no impacts from dust on the European sites during the demolition, earthworks and construction phases of the project. A ‘negligible’ impact from dust on ecology during the trackout phase was identified because of the potential for heavy vehicles to track dust and dirt on and off site adjacent to the European sites. However, this impact would be minimal because the majority of the site and all of the access road is laid to concrete or tarmac and the works will not generate more than 10 outward vehicle movements per day at most.

For this reason, it is concluded that the power generation project would not lead to a Likely Significant Effect on the European sites from dust.

5.4 Indirect loss of habitat from gaseous emissions and deposition, specifically emissions of Nitrogen Oxides (NOx) and ammonia and nutrient nitrogen and acid deposition

The Environmental Statement and Planning Support Statement both acknowledge that, without mitigation, it is likely that the proposed Power Generation project would lead to an increase in emissions from the Gathering Station and that this may affect the heathland vegetation surrounding the site.

For this reason, it is concluded that the Power Generation project would lead to a Likely Significant Effect on the European sites from generation of gaseous emissions and nutrient and acid deposition on the heathland habitat.

These effects (noise and air quality) will be discussed in the subsequent section which presents an Appropriate Assessment of the proposals, as set out in Regulation 63(1) of the Conservation of Habitats and Species Regulations, 2017.

6.0 Appropriate Assessment

It has been established that there are two pathways by which the Power Generation project at Wytch Farm Gathering Station could lead to adverse effect on the integrity of the relevant European sites. These are discussed individually below, while considering works methodology and mitigation. This part of the assessment enshrines the precautionary principle, and a conclusion of no effect on integrity can only be reached where there is certainty about this conclusion.

6.1 Disturbance to species which are interest features of the European sites from noise, during construction and operational phases

Noise during construction or from operation of the proposed Gas Turbines has the potential to affect Nightjar in the vicinity of the South Gathering Station area.

However, the works would be subject to the strict construction and operational noise limits for the Gathering Station which are enforced under planning condition (Application Number 6/2012/0591). This condition helped ensure that the Appropriate Assessment for the 2012 application could conclude that there would be no adverse effect on the integrity of the European sites, including impacts on Nightjar and it is reasonable to assume that compliance with this condition for the duration of the Power Generation project would lead to the same result.

In addition, the environmental assessment for the same 2012 Sect 73 Application to extend the operational life of the oilfields resulted in a condition restricting noise at Wellsites F & M ‘to reduce the level of disturbance to nesting nightjar in the vicinity of the oilfield installations to an inconsequential level’. Perenco have chosen to apply this noise specification to the proposed plant as a contractual requirement for the power generation project, resulting in additional certainty that Nightjars will not be adversely affected. These noise limits also have to be adhered to during the construction phase.

Table 3.2 in Chapter 3 of the Environmental Statement summarises the mitigation measures undertaken to ensure that the Power Generation project has a minimal impact on the environment. Listed mitigation includes placing the Gas Engines within a building (which incorporates an insulated wall) to further reduce noise emissions, which will also help ensure that noise generation is below the limit at which it would cause disturbance to Nightjar.

Taking these mitigation measures into consideration, it can be concluded that the proposed Power Generation project would not lead to an adverse effect on the integrity of the Dorset Heathlands SPA.

6.2 Air Quality

A detailed air quality study has been undertaken to evaluate the effects of the Power Generation project on the relevant European sites, taking proposed mitigation and known existing baseline conditions into account.

The air quality study uses standard methodology as advised by the Environment Agency and APIS. This is detailed in Chapters 6 and 7 of the Environmental Statement.

The first stage of this study was to identify the Zone of Influence within which ecological features may be subject to significant effects as a result of emissions from 12 the proposed development and associated activities. The maximum ZoI for the assessment was determined by the area within which predicted concentrations and deposition rates (of NOx, ammonia, N and acid deposition) exceeded the screening criteria of 1% and 10% of the critical load/level for long and short term impacts respectively, as set out by the Environment Agency.

A process can be considered insignificant if:

• The long term (annual mean) process contribution is <1% of the long term environmental standard, • The short term (15 minute, 1 hour, 24 hour mean) process contribution is <10% of the short term environmental standard.

It should be recognised that these criteria determine when an impact can be screened out as insignificant. They do not imply that impacts will necessarily be significant above one or both of these criteria, merely that there is a potential for significant impacts to occur that should be considered in more detail.

In addition, Environment Agency guidance states that, where Predicted Environmental Concentrations (PEC) or Process Contributions (PC) are below the critical level for an ecological receptor, impacts can be seen as not significant.

Figures 7.3 to 7.18 of the Environmental Statement present the results of the air quality modelling to determine the ZoI for each receptor site and for each potential pollutant.

Initial assessment results showed that impacts on the European sites from NOx could be discounted immediately. Although the screening criteria (1% and 10%) for annual and 24hr mean concentrations of NOx were exceeded over parts of some of the relevant European sites, the total annual mean and total 24 hour mean NOx concentrations were determined to reach, at most, 11.7microg/m 3 and 32.5microg/m 3 in the study area. This is well below the critical levels of 30microg/m 3 (for annual mean) and 75microg/m 3 (for 24 hour mean) and can therefore be discounted using the Environment Agency criteria above.

Additional certainty over this conclusion is provided by annual monitoring carried out by Perenco. Six of the 24 diffusion tubes deployed across the site are located in proximity to the Gathering Station and, when NOx results from these were compared to estimated NOx concentrations (using DEFRA maps) the results were found to be comparable.

Once the Zone of Influence had been determined, this was compared with the qualifying features of the Dorset Heathlands SPA and the Dorset Heaths (Purbeck and Wareham) and Studland Dunes SAC and critical loads for both sites were used to calculate the screening criteria of 1% (see table 6.5 in Chapter 6 of the Environmental Statement). This showed that the qualifying features of these sites (habitats) which needed further consideration were:

• North Atlantic wet heaths with Erica tetralix • Temperate Atlantic wet heaths with Erica ciliaris and E.tetralix • European dry heaths • Depressions on peat substrates with Rhynchosporion

The parts of the European sites within the ZoI are underpinned by Units 3 and 6 of Rempstone Heaths SSSI, the condition of which is regularly assessed by Natural England. Unit 3 is predominantly M25 Molinia mire and Unit 6 is ‘a mixture of extremely high-quality habitats’ approximating the M1 Sphagnum auriculatum bog pool community. Of these two habitat types M1 is the most sensitive and critical loads for both habitat types were used to calculate the screening criteria of 1%, presented in table 6.4, Chapter 6 of the Environmental Statement.

A screening assessment comparing the relevant European sites (and underlying SSSI units) with the calculated critical loads was carried out and is presented in table 6.6 of Chapter 6 of the Environmental Statement. The assessment did not include NOx for reasons stated above. The assessment found that:

• Acid deposition exceeded the screening criteria of 1% of the critical load over a small area of the Dorset Heaths (Purbeck and Wareham) & Studland Dunes SAC (Fig 7.4 of the Environmental Statement). • Annual mean ammonia exceeded the screening criteria of 1% of the critical load over a small area of the Dorset Heaths (Purbeck and Wareham) & Studland Dunes SAC (Fig 7.17 of the Environmental Statement) • Nitrogen deposition exceeded the screening criteria of 1% of the critical load over a small area of Unit 6 of Rempstone Heaths SSSI (Fig 7.9 of the Environmental Statement) • Annual mean ammonia exceeded the screening criteria of 1% of the critical load over a small area of Unit 3 of Rempstone Heaths SSSI. (Fig 7.18 of the Environmental Statement)

6.2.1 the Dorset Heaths (Purbeck and Wareham) & Studland Dunes SAC

Air quality emission/deposition modelling showed small exceedances of the 1% screening criteria for acid deposition and annual mean ammonia across small areas of this European site.

The data shows (para 7.7.18 of Chapter 7 of the Environmental Statement) that acid deposition would be 0.0004 keq/ha/yr above the 1% screening threshold of 0.0055 keg/ha/yr and the equivalent of 1.057% of the critical load. The baseline deposition level (0.82keq/ha/yr) already exceeds the critical load (0.558keq/ha/yr) in this part of the site but it is considered that such a small additional exceedance across such a small part of the European site would not lead to an adverse effect on the integrity of the site, especially when taking other mitigation measures into account.

The data shows (para 7.7.24 of Chapter 7 of the Environmental Statement) that annual mean ammonia emissions would be up to 0.0008microg/m 3 above the 1% screening threshold of 0.01microg/m 3 and the equivalent of 1.08% of the critical load. The baseline level already slightly exceeds the critical load (1.0microg/m 3) in this part of the site (by 0.03microg/m 3) but it is considered that such a small additional exceedance across such a small part of the European site would not lead to an adverse effect on the integrity of the site, especially when taking other mitigation measures into account.

6.2.2 Rempstone Heaths SSSI, Units 3 and 6

Air quality emission/deposition modelling showed small exceedences of the 1% screening criteria for nitrogen deposition in Unit 6 and annual mean ammonia in Unit 3 of Rempstone Heaths SSSI.

The data shows (para 7.7.21 of Chapter 7 of the Environmental Statement) that nitrogen deposition in Unit 6 of Rempstone Heaths SSSI would be 0.0033kgN/ha/yr above the 1% screening threshold of 0.05kgN/ha/yr and the equivalent of 1.066% of the critical load. The baseline level (13.44kgN/ha/yr) already exceeds the critical load (5kgN/ha/yr) in this part of the site but it is considered that such a small additional exceedance across such a small part of the SSSI underlying the European site would not lead to an adverse effect on the integrity of the site, especially when taking other mitigation measures into account.

The data shows (para 7.7.24 of Chapter 7 of the Environmental Statement) that annual mean ammonia emissions in Unit 3 of Rempstone Heaths SSSI would be up to 0.0008microg/m 3 above the 1% screening threshold of 0.01microg/m 3 and the equivalent of 1.08% of the critical load. The baseline level already slightly exceeds the critical load (1.0microg/m 3) in this part of the site (by 0.03microg/m 3) but it is considered that such a small exceedance across such a small part of the SSSI underlying the European site would not lead to an adverse effect on the integrity of the site, especially when taking other mitigation measures into account.

In summary, small exceedances of acid deposition, nitrogen deposition and annual mean ammonia (all equating to just over 1% of the critical load) for the relevant interest features of the SAC and underlying units of the SSSI were detected by air quality modelling. However, these exceedances are very small and should be considered in relation to ongoing and future land management programmes of the habitats within the designated areas, with the aim of improving their overall condition. This is of particular relevance to Unit 3 of Rempstone Heaths SSSI where Perenco have agreed that future management will focus on enabling other mire communities, such as M21 Narthecium ossifragum – Sphagnum papillosum mire to develop. These measures will support the conservation objectives of the SAC.

Other mitigation already accounted for in the assessment above includes:

• Use of gas engines specifically designed to reduce the annual average ammonia emission rate to 0.38mg/Nm 3, in line with the 2012 PA2 application. This was assessed under the Habs Regs with the conclusion that adverse effect on the integrity of the European sites would be avoided. • Use of gas engines specifically designed to reduce NOx emissions down to 3 65mg/Nm at 5%O 2, in line with the 2012 PA2 application. This was assessed under the Habs Regs with the conclusion that adverse effect on the integrity of the European sites would be avoided. • Fitting selective catalytic reduction technology to the gas engines to enhance the emissions performance of the engines beyond that required by compliance with the Industrial Emissions Directive.

Additional certainty that adverse effects on the integrity of the European sites is provided by results of the ongoing lichen survey (see Environmental Statement) which has been carried out every 2 years since 1990 to determine the effect of air pollution on lichen species around Wytch Farm and which shows that there has been no increase in species which respond to an increase in levels of ammonia and that pollution sensitive species are still present. The whole area lies within zones 8-9 of the Hawksworth-Rose scale (0 being heavily polluted and 10 the least polluted) and suggests that the air quality around Wytch Farm is good with minimal pollution. The proposed Power Generation project will be contractually bound to the same air quality standards as those imposed on the 2012 PA2 permission therefore it is

15 reasonable to assume that effects on air quality and sensitive ecological receptors will remain within the same parameters.

This Appropriate Assessment demonstrates that the Power Generation project will not lead to any adverse effects on the integrity of the European sites.

7.0 In combination Effects

In-combination effects could arise where appropriate assessment of a proposal alone has led to a conclusion of an inconsequential adverse effect on site integrity. However, when considered alongside another proposal with a similar effect, the adverse effect might be additive and no longer trivial.

Discussions between Natural England, the Competent Authority and Perenco have included consideration of where in-combination effects might arise out of this application. It was concluded that it is very unlikely that there would be in- combination effects that would alter the conclusions on the individual proposal alone. This is because:

• Other existing sources of pollutant concentrations are included into the background data and therefore already considered. • There are no other projects planned in the vicinity of the Gathering Station which could contribute to air quality and deposition on the heathland habitat.

It is also considered that there would not be any benefit in exhaustive search for unimplemented or uncompleted planning consents which deal with similar issues as it is considered very unlikely that there are significant in-combination effects between the current proposals and other developments.

8.0 Conclusion and Reg 63(5), the Integrity Test

The proposed Power Generation project at the Perenco Gathering Station, nr Corfe Castle, Dorset, has been assessed under Regulation 63 of the Conservation of Habitats and Species Regulations, 2017. The works were assessed in relation to components of the Dorset Heaths (Purbeck and Wareham) & Studland Dunes SAC and Dorset Heathlands SPA and Ramsar, underpinned by Units 3 and 6 of Rempstone Heaths SSSIs.

Although two pathways to Likely Significant Effect (noise and air quality) were recorded in association with these works, further investigation as part of the subsequent Appropriate Asessment showed that design of the gas engines to reduce noise and emissions, plus mitigation management of habitat which is a qualifying feature of the SAC will reduce these effects to a level below that which would cause adverse effect.

Therefore, it is concluded that the Power Generation project will not result in adverse effect on the integrity of the European sites, either alone or in combination with other projects, as described in Reg 63(5) of the Conservation of Habitats and Species Regulations, 2017.