JE30465 Chapter13 TelecomsAviationSF FINAL · communications by electrical or optical wire and...

Chapter 13: Telecommunications, Aviation, Shadow Flicker and Other Effects

Chapter 13: Telecommunications, Aviation and Shadow Flicker and Other Effects CF/AppDoc04/ES

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Contents 13. Telecommunications, Aviation and Shadow Flicker and Other Effects1

13.1. Overview 1 13.2. Introduction 1 13.2.1. Electromagnetic Interference 1 13.2.2. Aviation 1 13.2.3. Shadow Flicker 1 13.2.4. Ice 2 13.2.5. Driver Distraction 2 13.3. Policy Context 2 13.3.1. Electromagnetic Interference 2 13.3.2. Aviation 3 13.3.3. Shadow Flicker 3 13.3.4. Ice 4 13.4. Consultation 4 13.4.1. Electromagnetic Interference 4 13.4.2. Aviation 5 13.4.3. Shadow Flicker, Driver Distraction and Ice 5 13.5. Assessment Methodology 6 13.5.1. Electromagnetic Interference 6 13.5.2. Aviation 6 13.5.3. Shadow Flicker 7 13.6. Baseline 10 13.6.1. Electromagnetic Interference 10 13.6.2. Aviation 11 13.6.3. Shadow Flicker 11 13.7. Potential Significant Impacts 12 13.7.1. Electromagnetic Interference 12 13.7.2. Aviation 13 13.7.3. Shadow Flicker 14 13.7.4. Ice 17 13.7.5. Pre-development Tree Clearance 17 13.8. Mitigation Measures 17 13.8.1. Electromagnetic Interference 17 13.8.2. Aviation 17 13.8.3. Shadow Flicker 17 13.8.4. Ice 18 13.9. Residual Effects 18 13.9.1. Electromagnetic Interference 18 13.9.2. Aviation 18


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13.9.3. Shadow Flicker 18 13.9.4. Ice 18 13.10. Cumulative Impacts 18 13.11. Conclusion 19

Chapter 13: Telecommunications, Aviation and Shadow Flicker and Other Turbine Movement Issues CF/AppDoc04/ES

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13. Telecommunications, Aviation and Shadow Flicker and Other Effects

13.1. Overview

13.1.1. This Chapter identifies and describes the likely impacts of the Project on a number of specific issues associated with wind farm development and principally associated with the movement of turbine blades. The issues addressed in this Chapter are as follows:

• Electromagnetic interference (EMI) (see Section 13.2.1); • Aviation (see Section 13.2.2); • Shadow flicker (see Section 13.2.3); • Ice (see Section 13.2.4); and • Driver distraction (see Section 13.2.5).

13.1.2. This Chapter follows the same format as other assessment Chapters, as described in Chapter 1 (Introduction). For each of these issues there is no defined and accepted impact assessment methodology, except for shadow flicker assessments which is described in Section 13.5.3. For the other aspects addressed in this Chapter the assessment is based on author and industry experience, consultation, policy guidance and observation made from other wind farm projects in the UK.

13.2. Introduction

13.2.1. This section outlines an introduction to the assessment of each issue addressed in this Chapter.

13.2.1. Electromagnetic Interference

13.2.1.1. The operation of wind turbines can interfere with broadcast and other telecommunications services by causing electromagnetic interference (EMI), and the possibility of such interference is a material planning consideration. EMI can affect communication systems including television (TV) reception, mobile phone transmitters, microwave links, radar and aircraft navigation beacons.

13.2.2. Aviation

13.2.2.1. Wind turbines can result in potential impacts on aviation, both civil and military aircrafts. A description of the existing aviation environment of the Application Site is provided in this Chapter, which has been identified through consultation with national and local aviation organisations.

13.2.3. Shadow Flicker

13.2.3.1. Shadow flicker is a term used to describe the pattern of alternating light intensity observed when the rotating blades of a wind turbine cast a shadow on a receptor under certain wind and light conditions. An analysis of these conditions and the location of potential receptors has been undertaken. The results provide the number of hours in a year when a theoretical shadow flicker will occur. This is most pronounced during sunrise


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and sunset when the sun’s angle is lower and the resulting shadows are longer. In the UK, shadow flicker is most likely to be a problem in the winter months when the sun is lower in the sky and shadows are at their longest.

13.2.3.2. Strobing is reflected light occurring in a flashing pattern and can occur over large distances. This effect is now considered not be an issue as turbines are now made of light grey semi matt material as suggested in ETSU (1999) study and the Companion Guide to PPS22 (2004). Therefore the effects of strobing have not been considered further.

13.2.4. Ice

13.2.4.1. Wind turbines operating in cold climates may suffer from icing in certain weather conditions. A possible consequence of icy conditions is ‘ice throw’. Ice throw occurs when ice naturally builds up on the blade and is thrown off in pieces during wind turbine movement, potentially harming maintenance crew, the public and/or other users of the area.

13.2.5. Driver Distraction

13.2.5.1. TAN 8: Planning for Renewable Energy recognises that:

13.2.5.2. “there is no evidence that motor vehicle accidents have been caused as a result of drivers being distracted by the movement of wind turbine blades. Wind turbines should not be treated any differently from other distractions faced by a driver.” [Annex C, para 2.26]

13.2.5.3. The closest significant road to the Application Site is the B5105, located approximately 0.5 km to the south of Turbine 32. Given the distance between the turbines and the road, and the likelihood of mature trees to provide some level of screening, no significant impacts on driver distraction will occur as a result of operating the Project’s turbines. As such, this has been scoped out of the EIA and no further assessment is undertaken.

13.3. Policy Context

13.3.1. The Planning policy context is discussed in Chapter 4 (Planning and Energy Policy Context) and relevant policies are also discussed below.


13.3.1.1. There are no policy issues with respect to electromagnetic interference highlighted in EN-3.

13.3.1.2. Planning Policy Wales TAN 8 (2005): Planning for Renewable Energy acknowledges that:

13.3.1.3. “A wind turbine can interfere with the electromagnetic transmission in two ways – by emitting an electromagnetic signal itself, and by interfering with other electromagnetic signals. The very low level of electromagnetic radiation produced by the turbine itself poses no greater threat to health than do most domestic appliances.” [Annex C, para 2.29]


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13.3.1.4. “SSAs are largely unaffected by broadcast transmission, radar, MOD Mid Wales Tactical Training Area (TTA) and other constraints” [page 6, para 2.9]

13.3.1.5. “Preliminary discussions with NATS have indicated that there are no significant problems likely for wind farm development in the SSAs”[Annex C, para 2.38]

13.3.1.6. “Provided careful attention is paid to siting, wind turbines should not cause any significant adverse effects on communication systems which use electromagnetic waves as the transmission medium (eg television, radio and microwave links).”[Annex C, para 2.30]

13.3.1.7. This assessment is also based on guidance provided in Planning Policy Wales TAN 19. .

13.3.1.8. TAN 19, published in August 2002, gives guidance on planning for all forms of communications by electrical or optical wire and cable, and radio signals (whether terrestrial or from satellite), both public and private. It covers both the transmission of signals and the disruption of signals, the latter being relevant to the proposed development. It states that large prominent structures such as tower blocks, cranes, warehouses or wind farms, can cause widespread disruption to television and other telecommunications services due to the physical obstruction or reflection of the wanted signals. Digital television signals are far more robust than analogue. As viewers change to digital over time, this offers the prospect of the elimination of problems such as interference caused by reflections from structures.

13.3.2. Aviation

13.3.2.1. There are no policy issues with respect to aviation highlighted in EN-3.

13.3.2.2. Planning Policy Wales TAN 8: Planning for Renewable Energy states that:

13.3.2.3. “Developments within a specified radius of major airports and aerodromes are subject to mandatory consultation with the Civil Aviation Authority (CAA) and/or the Ministry of Defence (MoD) under the Town and Country Planning (Aerodromes and Technical Sites) Directive 1992.” [Annex C, para 2.35]

13.3.2.4. This guidance is also echoed within PPS 221. This guidance was taken into consideration and relevant bodies within the radius have been consulted.


13.3.3.1. EN-3 provides a number of guidelines and statements in relation to shadow flicker analysis and has been referred to throughout this assessment. This guidance states that the maximum horizontal distance between turbine location and potential receptor affected by shadow flicker is ten times the diameter of the turbine The companion guide to PPS22 states that properties within 130 degrees either side of north, relative to the turbines, can be affected at these latitudes in the UK – turbines do not cast long shadows on their southern side. In addition, it states that shadow flicker will only occur inside buildings where the flicker is occurring through a narrow window opening.

13.3.3.2. Planning Policy Wales TAN 8 (2005): Planning for Renewable Energy states that

1 ODPM (2004) Planning for Renewable Energy: A Companion Guide to PPS22


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13.3.3.3. “Developers should provide an analysis of the potential for shadow flicker impacting upon any nearby properties.” [Annex C, para 2.32]

13.3.3.4. However, it does not provide guidelines to undertake such an analysis.

13.3.4. Ice

13.3.4.1. There are no policy issues with respect to ice throw highlighted in EN-3.

13.3.4.2. TAN 8 highlights that the potential for ice throw on wind farms in Wales is low.

13.4. Consultation


13.4.1.1. RWE NRL has undertaken consultations with relevant parties. These parties were identified from the consultation with Ofcom and are as follows:

• Airwave Solutions Limited (MM02) • BBC; • BT MLL Telecom; • Cable & Wireless; • CSS Spectrum Management Services; • Joint Radio Company (JRC); • Ofcom; • Everything Everywhere Limited (Orange); • T-mobile; and • Vodafone.

13.4.1.2. These parties were contacted regarding the Project and a summary of responses from

operators who operate links within 6.5 km of the Project is provided in Annex 13.1 Telecommunications, Aviation and Shadow Flicker and other Turbine Movement Consultation, in the Consultation Report, and is summarised in Table 13.1.

Table 13.1 Microwave Links consultation responses within a 6.5 km Radius of the Project

Consultee Comments Everything Everywhere Limited (Orange)

No concerns confirmed by email dated 31st October 2012

Airwave Solutions Limited No concerns confirmed by email dated 15th October 2012

13.4.1.3. The operators which were consulted but not listed within Table 3.1 above had no concerns with the proposed development as they operated outside the zone of assessment (6.5 km). Note that consultation had been undertaken prior to the responses provided in Annex 13.1, however these responses are now superceded as the layout the project has evolved. A full consultation diary is provided within the Consultation Report.


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13.4.1.4. The BBC tool2 which addresses the impact of turbines upon TV reception was also used to predict the potential impact of the proposed development. The co-ordinates of the proposed turbines were entered into the BBC tool and results of this assessment are discussed in Section 13.7.1.

13.4.2. Aviation

13.4.2.1. Consultation with Defence Estates (who represent the MoD), the Civil Aviation Authority (CAA) and the National Air Traffic Services (NATS) has been conducted following the processes contained within PPS22 and the accompanying Companion Guide

3 which is

referred to in EN-3. All identified interested parties were contacted and provided with details of the preliminary layout and then again an amended final layout, following the review of other environmental and technical constraints. No aviation objections were received to the final layout and the responses received to the aviation consultations are summarised in Table 13.2 and contained within Annex 13.1.

Table 13.2 Summary of Aviation Consultation Responses

Consultee Response Civil Aviation Authority (CAA) No objection to the layout

Suggested consultation with NATS and Hawarden Airport Defence Geographic Centre to be notified of turbine positions once they are constructed so they can be plotted on aeronautical charts.

MOD No objection to the layout. Request that turbines are fitted with aviation lighting. (Initial objection due to DPA Warton Radar withdrawn once heights (metres AOD) of proposed turbines were provided to MOD and once other wind farm projects in similar settings were considered). Additional consultation with the MOD regarding the specification of the aviation lighting – only infrared lighting is required which isn’t visible to the naked human eye. This is now possible due to advances in technology resulting from trials undertaken by the MOD

NATS No objection to the proposed Project. Chester Hawarden Airport No objection from Chester Hawarden Airport Wales Air Ambulance No response received.

13.4.3. Shadow Flicker, Driver Distraction and Ice

13.4.3.1. Consultation responses relating to shadow flicker, driver distraction and ice from Section 47 consultees are not addressed in this Chapter but are addressed within the Consultation Report.

13.4.3.2. DCC raised concerns about the potential for all communities within 5km of the proposed development to be impacted by shadow flicker. As discussed within Section 13.5.3, only properties within 900m of the proposed turbines would be affected.

2 Available at: BBC Windfarms tool, available at http://windfarms.kw.bbc.co.uk/cgi-bin/rd/windfarms/windfarm.cgi 3 ODPM (2004). Planning for Renewable Energy: A Companion Guide to PPS 22.


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13.5. Assessment Methodology


13.5.1.1. In the UK, the Office of Communications (Ofcom) is the government agency with central responsibility for protection of the radio spectrum, including the assessment of electromagnetic interference from developments in the vicinity of a radio facility Ofcom and microwave link operators (see Section 13.4.1 were therefore consulted to establish the location of links close to the Project. This includes services operated by the emergency services and utility companies.

13.5.1.2. The British Broadcasting Corporation (BBC) and Ofcom are jointly responsible for terrestrial TV transmissions for domestic reception within the UK. The BBC’s wind farm assessment tool was used to identify properties potentially affected by the Project. Co-ordinates of the wind turbines are inputted into the model and the tool predicts what the impacts (if any) are likely to be for nearby households.

13.5.1.3. The locations of any EMI, radar or telecommunications links and the buffer zones requested by each organisation have been used to inform the constraints plan for the Project’s design.

13.5.1.4. The magnitude of impact that the Project will have on communication systems is categorised according to Table 13.3.

Table 13.3 Communication Systems Magnitude of Impact

Magnitude Definition

High Where the extent of impacts on receptors is large in scale (e.g. a signal will be completely lost) and a large number of people/activities will be affected (either positively or negatively).

Moderate Where the extent of impacts receptors is small in scale (e.g. some decline in TV or Where the extent of impacts on receptors is large in scale, but only a small number of people/activities will be affected (either positively or negatively).

Low Where the extent of impacts on receptors is small in scale and will only affect a small number of people/activities (either positively or negatively).

Negligible Where the extent of impacts on receptors is barely noticeable in scale and will only affect a very small number of people/activities (either positively or negatively).

No Change Where there is no change in the operation of telecommunications links, TV reception and radio communications.

13.5.2. Aviation

13.5.2.1. The most significant concern for aviation from wind farms is the potential for rotating wind turbine blades to generate unwanted returns on air traffic control and defence radar displays. The most effective way to ensure that the interests of all parties are balanced is through a process of consultation with appropriate parties responsible for aviation safety. In light of this, RWE NRL consulted with all the organisations that could be affected by the Project.


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13.5.2.2. There are no published guidelines or criteria for assessing and evaluating effects on aviation facilities within the context of an EIA. All aviation receptors are considered to have the same level of sensitivity, and therefore the identification of impact significance is based solely on the magnitude of the impact. Impact assessment evaluation criteria have therefore been developed on this basis, as presented in Table 13.4, which shows impact magnitude which can be either neutral (no change), positive or negative.

Table 13.4 Magnitude of Impact


Major The development will generate a significant loss of surveillance capability on the subject radar and/or will create an unacceptable operational impact on aviation. Mitigation is required.

Moderate The development will generate a reduction in surveillance capability and/or will have an operational impact that requires mitigation.

Minor The development will generate a reduction in surveillance capability and/or will only have a minimal operational impact.

Negligible The development will generate a slight reduction in surveillance capability and/or will have no operational impact

No Change There is no impact on radar performance and no operational impact

13.5.2.3. Major and moderate impacts are considered to be significant under the terms of the EIA Regulations and therefore require mitigation, whilst minor and negligible are not significant.


13.5.3.1. In England and Wales at present, there is no agreed level of shadow flicker defining a significant impact. However, the Danish Wind Industry Association noted on their website that, in Germany, the rule of thumb is that up to 30 hours shadow flicker a year received at a property is acceptable4; this level is upheld by the German legal system. The ‘Wind Energy Development Guidelines, 2006’5 published by the Irish Government Department of the Environment, Heritage and Local Government recommend that shadow flicker at neighbouring offices and dwellings within 500 m should not exceed 30 hours per year or 30 minutes (0.5 hours) per day. It should be noted that the receptors to the Project are all over 800 m from the nearest proposed turbine location. These recommendations are credited to Predac6, however, the distance from the nearest turbine is not stated. The most commonly quoted figure within the industry as an acceptable limit in the UK is less than 30 hours per year of theoretical shadow flicker. The thresholds of 30 minutes per day and 30 hours per year will be the significance criteria used for this assessment for all potential receptors. However, a conservative approach of applying this to all potential receptors within 10 rotor diameters (900m) of the proposed turbines will be adopted.

4 Available at: www.windpower.org 5 Wind Energy Development Guidelines, 2006’ Irish Government Department of the Environment, Heritage and Local Government. 6 Available at: www.cler.org/info/IMG/pdf/WP8_ANG_guide.pdf


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13.5.3.2. The distance between receptors and turbines has a large impact on the intensity of shadow flicker. Shadow flicker intensity can be defined as the difference in brightness between presence and absence of a shadow at any given location. This study does not examine variations in intensity, but rather the occurrence in the number of hours shadow flicker may occur, whether or not this is clearly distinct or barely noticeable. The assessment assumes a conservative worst case of bright sunshine conditions in all periods when flicker may occur.

13.5.3.3. Considering all of the points above, the likelihood of shadow flicker occurring is greatest when the circumstances listed below exist simultaneously:

• The receptor is at a position which is between 130° clockwise and anticlockwise from north and located within 10 turbine rotor diameters of the wind turbine (900m);

• The sun is shining and visible in the sky (not behind cloud) 7 ; • The wind turbine is in operation (wind speed is 4m/s to 25 m/s); and • The turbine blades are perpendicular to the line between the sun and the observer or

receptor.

13.5.3.4. It should be noted that for shadow flicker to be an issue, the use of the affected room is a limiting factor. If the affected room is a bedroom, its use during daylight hours may only be limited to 1-2 hours depending on individual habits. For living areas, the use may well be during daylight hours assuming the householders are not at work.

13.5.3.5. In this instance, as the maximum turbine rotor diameter will be 90 m, an area envelope of 900 m from the nearest turbine has been used in shadow flicker analyses. Therefore, receptors beyond 900m from the proposed turbines would not typically be affected. At this distance the blades can only produce fractional obscuration and the effect is highly diminished. Figure 13.1 shows this study envelope.

13.5.3.6. Terrain can act as an obstacle, significantly reducing or eliminating the impacts of shadow flicker, as can simple geometry relating to the position of the sun and the angle of the turbine blades in relation to this. An assessment of the impacts of terrain has also been made.

13.5.3.7. Weather conditions at the Application Site such as bright sunshine will greatly enhance the occurrence and intensity of shadow flicker, whereas haze or fog will cause a reduction. Receptors further away from the turbines, which may have experienced a shadow flicker impact under bright sunshine conditions, will, as a result of haze or fog, experience either no impact or one which is greatly reduced in intensity.

13.5.3.8. Shadow flicker calculations have been made using ReSoft WindFarm software. The model used in this analysis is very conservative and assumes the following conditions:

• There are clear skies every day of the year; • The wind turbines are always operating;

7 The average total annual sunshine in the United Kingdom is 1339.7 hours, which is just under 30% of the maximum possible (1971-2000 averages UK Met Office www.metoffice.gov.uk)


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• The blades of the wind turbines are always perpendicular to the line from the turbine to the sun (so that the shadow is always at its maximum possible size and circularity, rather than elliptical);

• There are no trees, buildings or vegetation on the surface which may obscure the line of sight between receptor and turbine; and

• The sun can be represented as a single point.

13.5.3.9. In practice it is likely that shadow flicker impacts would occur for considerably less time than the worst case conditions listed above as the modelling is worst case. At all other times, shadow flicker is therefore unlikely to occur.

13.5.3.10. The following data inputs were used in this study:

• A digital elevation model of the Application Site; • Latitude and longitude at centre of the Application Site used to calculate the

position of the sun; • Angle between True North and Grid North (1° 11’ East- taken from OS Explorer

Map 264); • Turbine locations – coordinates (identified in GIS); • Turbine rotor diameter (maximum 90 m); • Height to bottom of Turbine hub (maximum 100 m); • Façades of receptors facing a turbine identified as being ‘windows’ (identified in

GIS) - identifying – coordinates and angle it faces (0 to 359 degrees, all calculated using GIS);

• Tilt angle of the ‘window’ (always assumed horizontal); • Size (height and width) of the ‘window’ (always 10 m wide and 5 m high); and • Height above ground level of the ‘window’ (always 2 m).

The significance criteria for shadow flicker is provided below in Table 13.5.


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Table 13.5 Significance Criteria for Shadow Flicker


Major

The development will generate shadow flicker at a large number of properties within the zone of potential shadow flicker influence for a large proportion of any given operational year. The duration of shadow flicker predicted will greatly exceed the thresholds of 30 minutes per day and 30 hours per year.

Moderate

The development will generate shadow flicker at a small number of properties within the zone of potential shadow flicker influence for a large proportion of any given operational year or at a large number of properties for a small proportion of any given operational year. The duration of shadow flicker predicted will exceed the thresholds of 30 minutes per day and 30 hours per year.

Minor The duration of shadow flicker predicted is below the thresholds of 30 minutes

per day and 30 hours per year at properties within the zone of potential shadow flicker influence.

Negligible

The development will generate shadow flicker at properties within the zone of potential shadow flicker influence for a small proportion of any given operational year. The duration of shadow flicker predicted duration is significantly below the thresholds of 30 minutes per day and 30 hours per year.

No Change

Shadow Flicker is not predicted to occur at properties within 10 rotor diameters of the proposed development or there are no receptors within the zone of potential shadow flicker influence.

13.6. Baseline


13.6.1.1. The only links to operate across the Application Site are those operated by Orange and MM02,, who operate microwave links within the southern part of the Application Site. A site visit was conducted to verify end co-ordinates which had been provided by these organisations for their links. This detailed ground truthing exercise indicated that the MM02 links ran parallel to the Orange links, between the same masts. The constraint is two links based on current information as illustrated in Figure 13.2, but for the purposes of this assessment will be treated as one link due to the commonality of the masts involved.

13.6.1.2. Ofcom did not identify any other links within a 3 km radius. The links identified across the Application Site are illustrated in Table 13.6.


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13.6.1.3.

Table 13.6 Microwave Links within a 3 km radius of the Project

Links Company 0487966/1 Everything Everywhere Limited / MM02 / Orange 0504703/2 Airwave Solutions Limited 0428138/2 Airwave Solutions Limited 0512314/2 Everything Everywhere Limited 0510379/1 Airwave Solutions Ltd

13.6.1.4. In addition to the microwave links, the Moel-y-Parc transmitter, which is a digital TV transmitter, is located approximately 19 km from the northwest of the Application Site.

13.6.2. Aviation

13.6.2.1. Airports and airfields in the area were identified and are shown in Figure 13.3.

13.6.2.2. The site is located within a MOD low priority ‘Low Flying Zone’ which means that it is located within an area where the MOD are less likely to raise concerns.


13.6.3.1. The Project is located in a sparsely populated area of dense, predominantly conifer forest. There are few buildings and residential properties within the immediate area of the majority of the turbines.

13.6.3.2. Five houses in the vicinity of the Application Site have been identified as being within 900 m (10 rotor diameters) of a proposed turbine location (see Table 13.4 for nearest turbine). These are the properties in which shadow flicker could potentially occur under the perfect conditions described in 13.5.3. Each façade facing towards a turbine was assumed to have a window; using Ordnance Survey 1:10,000 base mapping 18 windows were identified for further analysis. These are listed in Table 13.7.

Table 13.7 Location of Shadow Flicker Receptors

Receptor Name Window BNG Easting [m] BNG Northing [m] 1 Bron Bannog (nearest turbine #

27) 1 2

303234 303241

352806 352804

2 Brynbach (nearest turbine # 2) 3 4

302114 302102

358764 358765

3 Cruglas (nearest turbine # 19) 5 6 7

302930 302923 302923

353838 353838 353846

4 Hafotty Hendre (nearest turbine # 28) 8

9 10

300245 300248 300245

351309 351318 351327

5 Tal-y-cefn Uchaf (nearest turbine # 24)

11 12

299742 299745

352742 352732


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Receptor Name Window BNG Easting [m] BNG Northing [m] 13 14 15 16 17 18

299750 299751 299746 299729 299722 299723

352725 352718 352715 352728 352715 352707

13.6.3.3. At this Application Site the location of trees, which are predominantly evergreen conifers,

will play a significant role in eliminating potential shadow flicker in the winter months and early morning and late evenings, however it cannot be assumed that these will always be present to offset effects of shadow flicker.

13.7. Potential Significant Impacts

13.7.1. This section addresses the potential significant impacts.


13.7.1.1. Radio Communications

13.7.1.2. No radio links have been identified which may be affected by the Project. No potential impacts are therefore predicted on radio links.

13.7.1.3. Microwave Links

13.7.1.4. Microwave links can be affected by reflection, blocking and radio frequency interference

13.7.1.5. Two parallel microwave links, one for Everything Everywhere Limited and one for Airwaves Solutions Limited that use the same transmitter, have been identified within the southern part of the Application Site (see Figure 13.2).

13.7.1.6. Planning Policy Wales TAN 8 (2005): Planning for Renewable Energy recommends that

13.7.1.7. “specialist organisations responsible for the operation of the electromagnetic links typically require a 100m clearance either side of a line of sight from the swept area of turbine blades” [Annex C, para 2.30].

13.7.1.8. A 100 m clearance of the identified microwave links has therefore been implemented as a constraint in the design evolution of the Project. The operators of these links have confirmed that they have no concerns with the proposed turbine locations and dimensions based on this 100 m clearance.

13.7.1.9. Therefore, no potential impacts are predicted on the microwave links found within the Application Site, or those located beyond the boundary of the Project.

13.7.1.10. TV Reception

13.7.1.11. For broadcast systems, such as TV, a wind farm located between a TV transmitter and a receiver aerial may cause loss of picture detail, loss of colour or buzz on sound.


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Viewers situated to the side of a wind farm may experience a delayed image or ‘ghost’ on the picture, or find the picture liable to flicker as the blades rotate. In some cases, a wind farm can also affect the re-broadcast link (RBL) feeding the transmitter.

13.7.1.12. According to the BBC wind farm tool, the Moel-y-Parc transmitter is likely to be affected by the Project

8. However, the BBC tool indicates that whilst the transmitter could be

affected no homes, for which there is no alternative off-air service9, are likely to be

affected.

13.7.1.13. A potential impact which could occur is ‘ghosting’, which can be caused by minor reflections of the signal. This is more significant issue for properties utilising analogue signals through traditional aerial facilities than for those using digital signals. Broadcast digital TV signals received via aerial facilities (typically through a ‘freeview box’), greatly compress sound and pictures in order to be transmitted on the same digital signal, so several TV channels can be transmitted using the same bandwidth as just one analogue channel. This makes it a much more effective and efficient way to transmit TV signals. Digital TV transmission does not generally suffer from ‘ghosting’ but sudden picture degradation may occur in extreme circumstances due to signal reflections. Roll-out of digital services was due to be completed in Wales by July 2010 and the Moel-y-Parc transmitter and all its relays have completed the digital switchover3.

13.7.1.14. TAN 19 Telecommunications states:

13.7.1.15. “Digital television signals are far more robust than analogue and, as viewers change to digital over time, offer the prospect of the elimination of such problems as interference caused by reflections from structures.” [page 24, para 91]

13.7.1.16. Therefore based on the above, it is considered that there will be no significant impacts on TV reception.

13.7.2. Aviation

13.7.2.1. TAN8 Para 2.36 states that “Lights are only required on structures that are over 150m high. There are currently no turbines of this height in the UK.” This means that the turbines at the Application Site will not require aviation lighting to comply with this guidance as they fall below this height.

13.7.2.2. However, the MOD have expressed that if the wind turbines are installed without aviation lighting they would pose a risk to low flying military aircraft. This would pose a risk and would constitute a potential impact of the Project. This is a recent requirement from the MOD.

13.7.2.3. No other issues or objections to the Project and its layout were highlighted from the consultation undertaken. It can be concluded that no further assessment is required as there are no potential impacts predicted from the Project.

8 Source: BBC Windfarms tool, available at http://windfarms.kw.bbc.co.uk/cgi-bin/rd/windfarms/windfarm.cgi 9 An off-air TV signal is one broadcast from stations on the ground and received through an indoor or outdoor antenna. 3 Source: http://www.digitaluk.co.uk/transmitternetwork/transmitter_groups/moel_y_parc


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13.7.3.1. The companion guide to PPS22 states that around 0.5 % of the UK population is, to some degree, epileptic and of these around 5 % are photo-sensitive. Of photo-sensitive epileptics, less than 5 % are sensitive to low frequencies of 2.5-3 Hz, the remainder are sensitive only to higher frequencies. As modern turbines are known to operate at levels below 1Hz, seizures caused by shadow flicker are considered to be extremely unlikely.

13.7.3.1. Preliminary Assessment

13.7.3.1.1. The results of the desk based shadow flicker assessment are presented in Table 13.8, and illustrate the times of year theoretical shadow flicker occur at each of the 18 ‘windows’ in the analysis, assuming each and everyday is brilliant sunshine.

Table 13.8 Summary of Shadow Flicker Impacts at Each Receptor

Name Window Days per year Max hours per day

Mean hours per day Total hours*

Bron Bannog 1 69 0.47 0.33 22.7

2 62 0.47 0.35 21.7

Brynbach 3 42 0.45 0.36 15.2

4 46 0.48 0.37 17

Cruglas 5 50 0.45 0.34 17.2

6 91 0.51 0.38 34.8

7 39 0.49 0.39 15.1

Hafotty Hendre 8 60 0.49 0.38 23

9 64 0.49 0.38 24.1

10 0 0 0 0

Tal-y-cefn Uchaf 11 10 0.36 0.28 2.8

12 10 0.38 0.28 2.8

13 12 0.39 0.29 3.4

14 12 0.41 0.29 3.5

15 0 0 0 0

16 0 0 0 0

17 0 0 0 0

18 0 0 0 0 *Note that figures in bold are above the threshold

13.7.3.1.2. Table 13.5 illustrates that where theoretical shadow flicker does occur during the year at 13 of the 18 windows analysed, this is never for longer than 30 minutes on any one day (the other two windows do not receive any theoretical shadow flicker during the year). 14 of the windows predicted to experience shadow flicker do not incur potential effects for more than 30 hours in a year. Based on the criteria presented in Section 13.5.3, the


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impact at these locations is, therefore, not considered significant because they all fall below the threshold.

13.7.3.1.3. One of the windows at Cruglas (window 6) exceeds the threshold of 30 hours or less per year with a result of 34.8 hours per year being predicted, This result of 34.8 hours per year should be considered as potentially ‘significant’ for the purposes of this EIA. However, OS mapping indicated forestry located between the proposed turbine location and Cruglas which would act as a physical barrier to long shadows. Cruglas itself is surrounded by trees, many of which are likely to be mature trees, therefore, it is assumed the impact from shadow flicker will be reduced. However, it cannot be assumed that this forestry will remain in place and, therefore, further assessment was required. This is presented in the following section.

13.7.3.2. Detailed Assessment

13.7.3.2.1. As the preliminary modelling exercise within Section 13.7.3.1 indicated one small exceedence of the threshold values for shadow flicker, a more detailed assessment was undertaken. The intention of the detailed assessment was to allow site specific data to be entered into a model for shadow flicker such as measurements of window sizes to make the modelling input as realistic as possible. An exceedence of the threshold values was only experienced at one property, Cruglas, however, due to the conservative nature of the modelling, it was decided that all potentially affected properties would be analysed in greater detail to determine more representative shadow flicker results.

13.7.3.2.2. For the detailed assessment, a site survey was undertaken on 21st March 2012, where possible, at all identified receptors as shown in Table 13.8 to measure the orientation, tilt and approximate sizes of windows. Where measurements were not possible conservative assumptions have been made. The results of the house survey were then inputted into the ReSOFT model for the Application Site and revised shadow flicker calculations were undertaken. The results of this more detailed modelling are provided in Table 13.9. These results, as is the case with those presented in Table 13.8, are not corrected to take account of likely cloud cover across the Application Site ie the results assume each and every day is sunny with clear skies.


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Table 13.9 Summary of Revised Shadow Flicker Impacts at Each Receptor

Receptor Name Window Number Days per year Max hours

per day Mean hours

per day** Total Hours

Cruglas

1 2 3 4 5 6 7 8

48 48 47 48 87 85 85 37

0.44 0.44 0.44 0.44 0.47 0.46 0.47 0.46

0.34 0.34 0.34 0.34 0.35 0.36 0.36 0.37

16.2 16.2 16.2 16.2 30.7 30.2 30.5 13.6

Hafotty Hendre

9 10 11 12 13 14

57 60 62 59 59 59

0.47 0.47 0.47 0.47 0.47 0.47

0.36 0.35 0.35 0.35 0.35 0.35

20.3 21.1 21.4 20.8 20.5 20.8

Bron Bannog

15 16 17 18 19 20

49 49 50 52 52 53

0.45 0.45 0.44 0.45 0.45 0.44

0.32 0.32 0.32 0.33 0.33 0.32

15.7 15.9 16.1 17.2 17.1 17.1

Bryn Bach 21 22 23 24

42 41 41 42

0.43 0.43 0.43 0.43

0.35 0.35 0.34 0.35

14.5 14.2 14.1 14.9

*Note that figures in bold are above the threshold **Note that 0.33 hours is 20 minutes etc and therefore less than 0.5m is below the threshold of 30 minutes.

13.7.3.2.3. It was not possible to undertake a survey at Tal-y-cefn Uchaf due to access restrictions and therefore the results from the original assessment have been used. The results for Tal-y-cefn are well below the significance thresholds and no further assessment was required in any case.

13.7.3.2.4. For Cruglas, where there was an exceedance of the 30 hour threshold in the previous desk based assessment, the detailed modelling found that a single window was slightly above the threshold for total hours per year at 30.5 hours compared to the threshold of 30 hours indicating a potential impact with respect to shadow flicker at the property. No exceedances of more than 30 minutes per day were identified.

13.7.3.2.5. The other properties included in the detailed modelling all show shadow flicker occurrence to be below the 30 hour threshold with values ranging from 13.6 hours to 21.4 hours. It should be noted that the results presented here are worst case as explained in 13.5.3.


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13.7.4. Ice

13.7.4.1. Ice throw is only deemed a potential problem where there is the possibility of human receptors being in close proximity to the wind turbines. Clocaenog Forest is open access under the Countryside Rights of Way (CRoW) Act, 2000 with a number of public footpaths near some of the Project’s turbines (refer to Chapter 7 (Land Use and Forestry)). In addition, FCW also allows third party recreational activities to occur on site, so there is the potential for site users to be at risk from ice throw.

13.7.4.2. TAN 8 Planning for Renewable Energy states that:

13.7.4.3. “The build-up of ice on turbine blades is unlikely to present problems on the majority of sites in Wales. Even when icing does occur the turbines’ own vibration sensors are likely to detect the imbalance and inhibit the operation of the machines.” [Annex C, para 2.34].

13.7.4.4. Therefore, no residual effects are predicted due to the low likelihood of ice throw occurring.

13.7.5. Pre-development Tree Clearance

13.7.5.1. Pre-development tree clearance required for the proposed wind farm ahead of construction is not relevant to potential impacts on electromagnetic interference (EMI), aviation, shadow flicker, ice throw and driver distraction as these are all operational impacts. Additionally, the shadow flicker assessment does not take tree cover afforded by the forest into consideration. Therefore pre-development tree clearance ahead of construction or once operational is not relevant to this assessment. On this basis it is, as discussed previously, a worst case assessment approach. Mitigation for the shadow flicker is discussed within the next section.

13.8. Mitigation Measures

13.7.5.2. The mitigation measures are summarised in Chapter 16 (Mitigation & Enhancement) and also below.


13.8.1.1. No significant impacts are predicted and therefore no mitigation measures will be required.

13.8.2. Aviation

13.8.2.1. The turbines will be fitted with infrared lights to aid navigation as agreed with the MOD. The Defence Geographic Centre will be notified of turbine positions once the turbines are constructed so they can be plotted on aeronautical charts.


13.8.3.1. As there are exceedances of the thirty hours per year threshold for shadow flicker at Cruglas, mitigation in the form of light meters and shadow flicker timers are proposed to be installed on turbines 19 and 23 in the event that shadow flicker is found to be a nuisance. This would mean that the turbines will then be shut down when shadow flicker is predicted to occur by the meter and timers.


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13.8.4. Ice

13.8.4.1. To avoid potential impacts from ice throw, ice detectors will be incorporated into wind turbines if the turbine specification allows for this. If ice is detected on a wind turbine, it will be shut down.

13.8.4.2. If the turbine specification does not allow for incorporation of ice detectors, alternative recognised measures will be employed to reduce this risk. These will include one or more of the following:

• Halting operation of turbines during periods of ice accretion; • The use of warning signs alerting anyone in the area of the risk; and

13.9. Residual Effects


13.9.1.1. There will be no significant, residual impacts on radio communications, microwave links and TV.

13.9.2. Aviation

13.9.2.1. With the application of infrared aviation lighting to wind turbines it is predicted that no residual effects will occur on the flight activities of military aircraft. Whilst the turbines will be visible at night to aircraft equipped to see infrared, it does not represent a change in aviation safety and is therefore not considered to be a significant impact of the Project. No other aviation impacts or concerns have been predicted or raised by consultees.


13.9.3.1. No residual significant effects are predicted.

13.9.4. Ice

13.9.4.1. As highlighted in TAN 8, the potential for ice throw on wind farms in Wales is low. Further if ice detectors are utilised they will remove the potential for ice throw completely. If ice detectors cannot be incorporated into turbine specification, the risk of ice throw will be minimised through the alternative measures described. Residual effects associated with ice throw are therefore not considered to be significant.

13.10. Cumulative Impacts

13.10.1. No cumulative impacts are predicted with respect to electromagnetic Interference, aviation, ice throw and driver distraction.

13.10.2. As there are no proposed, existing or consented wind turbine developments within 900 m of the receptors assessed, and therefore, no cumulative impacts are possible.


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13.11. Conclusion

13.11.1. This Chapter identifies and describes the likely impacts of the Project on a number of specific issues associated with wind farm development and principally associated with the movement of turbine blades. This Chapter has assessed electromagnetic interference (EMI), aviation, shadow flicker, Ice throw and driver distraction.

13.11.2. In assessing the potential impacts, RWE NRL and the EIA team have consulted widely to establish the presence of existing EMI systems and aviation constraints within the area and to ascertain whether, in the stakeholders’ professional opinions, the proposed development will cause an impact. No effects have been identified although the wind turbines will need infrared lighting for low flying aircraft. The adoption of an appropriate site layout has also mitigated any impacts on EMI systems.

13.11.3. The assessment for shadow flicker has indicated that there is there is a slight exceedance of the threshold values at potential receptors. Therefore, in the event of nuisance caused by shadow flicker, mitigation is proposed in the form of shadow flicker timers and light meters which would be installed on turbines 19 and 23.

13.11.4. Driver distraction has been scoped out of the EIA owing to guidance within TAN 8 which suggests that there is a lack of evidence for driver distraction as a result of wind turbines.

13.11.5. The closest significant road to the Application Site is the B5105, located approximately 0.5 km to the south of Turbine 32. Given the distance between the turbines and the road, and the likelihood of mature trees to provide some level of screening, no significant impacts on driver distraction will occur as a result of operating the Project’s turbines. As such, this has been scoped out of the EIA and no further assessment is undertaken.

13.11.6. As highlighted in TAN 8, the potential for ice throw on wind farms in Wales is low. Further if ice detectors are utilised they will remove the potential for ice throw completely. If ice detectors cannot be incorporated into turbine specification, the risk of ice throw will be minimised through the alternative measures described. Residual effects associated with ice throw are therefore not considered to be significant.

13.11.7. There are no cumulative impacts predicted with respect to EMI, aviation, shadow flicker, ice throw and driver distraction.

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