Oweninny Wind Farm. Oweninny Power Ltd. Environmental Impact Statement. Chapter 2. Description of Project

Transcription

1 Oweninny Power Ltd. Chapter 2 Description of Project Copyright ESB International Limited, all rights reserved.

2 Table of Contents 2. DESCRIPTION OF PROJECT BACKGROUND THE DEVELOPERS ESB Wind Development Bord na Móna THE SITE PROJECT HISTORY Planning at Oweninny Delay in Grid Connection Duration of Permission Integrated Pollution Prevention Control License DESCRIPTION OF SCHEME Scheme Components Wind Turbines Transformers Site entrance Access Tracks Access to Coillte Teoranta s Cluddaun proposed wind farm site Crane stands Electrical Substation Meteorological masts Overhead Transmission Lines and Underground Cables Visitor Centre Temporary Site Compound Batching Plant Wastewater treatment facilities Borrow pit Bord Gáis Network Water supply Electricity supply River and stream crossings MATERIAL QUANTITIES PEAT STABILITY RISK ASSESSMENT INDICATIVE PROJECT PHASING Phasing OPERATION, MAINTENANCE AND DECOMMISSIONING Operation and Maintenance Decommissioning MITIGATION OF POTENTIAL IMPACTS 2.31 iii

3 2. 11 OTHER DEVELOPMENTS GRID CONNECTION 2.32 List of Tables Table 2-1: History of planning at Oweninny Table 2-2: Candidate Wind Turbines* Table 2-3: Locations of Turbines Table 2-4: Electrical Substation Locations (Centre point) Table 2-5: Meteorological Mast Table 2-6: Borrow Pit Location Table 2-7: Estimates of material quantities List of Plates Plate 2-1: Bellacorick power station List of Figures Figure 2-1: Site Layout Figure 2-2: Typical turbine components (ESB Curryfree wind farm) Figure 2-3: Typical Wind Turbine Nacelle (Courtesy of Nordex) Figure 2-4: Access locations to Oweninny site off the N Figure 2-5: Typical tower structure Figure 2-6: Borrow pit and gravel storage area Figure 2-7: Oweninny Visitor Centre- Site Plan Figure 2-8: Oweninny Visitor Centre Elevation Figure 2-9: Contractors main site compounds Figure 2-10: Contractors typical site compound layout Figure 2-11: Typical batching plant layout Figure 2-12: Project indicative phasing Figure 2-13: Location of other projects near Oweninny iv

4 2. DESCRIPTION OF PROJECT 2. 1 BACKGROUND Oweninny Wind Farm will be developed by Oweninny Power Ltd, a joint venture between ESB Wind Development Limited and Bord na Móna Energy Limited. The wind farm will comprise 112 wind turbine generators, each of approximately 2,500-3,500 kilowatt (kw) capacity. The rated electrical output of the wind farm will be approximately 370 Mega Watts (MW) and the electricity generated will be supplied into the deregulated electricity market on the national electricity network. The development will also include: Four electrical substations, Underground cables from the wind turbines to the substations, 85 kilometres of access tracks (these will be largely new with c.6km of existing access tracks being upgraded), One operation and maintenance building, Two 110 kv overhead lines, (circa 1.7 km from Electrical Substation 1 and 2.5 km from Electrical Substation 2) comprising angle masts and twin wooden pole sets connected to the existing Bellacorick substation by two underground electricity cables. A visitors centre, Eight permanent meteorological masts Temporary works will include A borrow pit to provide material for access track construction Concrete batching plant with associated materials storage Contractor(s) construction lay down area and materials storage area THE DEVELOPERS The joint developers of Oweninny Wind Energy Project are Bord na Móna Energy Limited and ESB Wind Development Limited. A joint venture company, Oweninny Power Limited has been established for this purpose with registered offices at ESB International, Stephen s Court, St. Stephens Green, Dublin ESB Wind Development History ESB Wind Development is the part of the ESB organisation that is dedicated to implementing ESB s policy in relation to developing wind energy projects. ESB has been to the fore in the development of renewable energy in Ireland and has developed all the major hydropower schemes in Ireland. In relation to wind energy, it has carried out development programmes in the 1950s, 1980s and 1990s, but it is only in the past Project Description 2.1

5 decade that wind generating technology has matured world-wide. As a company ESB contributed 18 billion to the Irish economy in 2012 through purchases from Irish suppliers, taxes, rates, wages and dividends. ESB is Ireland s largest generator of green electricity and the company s commercial wind portfolio has expanded to include a number of developments on its own and in partnership with others. In this context, 60 MW of renewable wind generation was commissioned in Ireland by ESB in Mountain Lodge Wind Farm in Co. Cavan comprising 23 turbines added a further 35 MW in A number of developments with a combined capacity of approximately 60 MW were commissioned in 2010 and in 2011 an additional 96 MW of new wind generating capacity was added. The company has also been developing its renewables business in Northern Ireland and Britain, where it is the owner of projects with a combined generating capacity of more than 150 MW. At 66 MW capacity, its recently completed Fullabrook Wind Farm is one of the largest onshore wind farms in England. In 2012 Carrickatane (21 MW ) windfarm in Co. Derry was commissioned and erection of turbines completed in 2013 at the 35 MW windfarm in Myndd y Betwys in Wales, bringing ESB s total operational wind portfolio to 380 MW. In 2012 ESB s share of generation on an all-island basis was 48%. ESB Independent Generation is responsible for the long-term asset management, commercial management and trading of ESB's portfolio of wind farms and is supported by ESB O&M Solutions which is responsible for operating and maintaining ESB's wind farms. Future Policy In March 2008 ESB announced that the company was to embark on an unprecedented capital investment programme of 22 billion. The company made capital investments of 819M in The Board of ESB has approved a Strategic Framework to Achieve carbon neutrality across all markets by 2050 Cut ESB s carbon intensity (-50% by 2025, -85% by 2035 vs 2005 levels) Grow the % of renewables in the generating mix (from 12% to 26% by 2025). This will see major company investment in renewable energy, the halving of its carbon emissions within 12 years and the achievement of carbon net-zero by The plan, which will establish ESB as a world class renewables company, makes emissions reduction and energy efficiency central to its ambitious targets. By 2030, ESB will be delivering one-third of its electricity from renewable generation. This will include over 1,600 MW of wind generation, in addition to wave, tidal and biomass. To promote this, the company will invest in emerging green technologies. The investment by ESB in its Networks will ensure continued efficient delivery of the vital infrastructure needed to support the Irish economy. It will also facilitate the development of up to 6,000 MW of wind on the island Bord na Móna Bord Na Móna Energy Limited is a wholly owned subsidiary of Bord na Móna plc. Bord na Móna currently owns around 80,000 ha of peatlands and employs approximately 1,800 people at 30 locations mainly in Ireland, but also in the United Kingdom and the United Project Description 2.2

6 States. In recognition of the finite nature of the peat resource, Bord na Móna has embarked on a strategy of diversification from its core peat based businesses of horticultural products, peat harvesting and peat based fuel supply. In recent years Bord na Móna has branched out into new sectors, including electricity generation, heating solutions, resource recovery (waste), water treatment systems and environmental consulting. The company is responsible for the supply of 38% of Ireland s energy derived from indigenous resources and thus helps to reduce the degree of external dependence and contribute to the security of Ireland s energy supply. Bord na Móna Energy Limited is seeking to position itself as one of the leading power generation companies participating in the wholesale all-island market for electricity, thus contributing to the security, reliability and sustainability of the Irish electricity system. The strategy to deliver this vision is to develop a portfolio of power generation plants, centred on renewables. The renewable portion will include the development of wind farms on suitable areas of cutaway peatlands, and on co-fuelling the Edenderry power station with biomass. The balance of the portfolio will consist of complementary flexible thermal generation. Bord na Móna Energy Limited currently owns and operates the 128 MW peat fired power station close to Edenderry, Co Offaly. Renewable Energy Ireland Ltd, of which Bord na Móna is a majority shareholder is a subsidiary of Bord na Móna Energy Limited, and is and the holding company and the operator of the 6.45 MW Bellacorick wind farm in Co. Mayo. Bord na Móna Energy Limited has secured planning permission to construct 80 MW and 40 MW wind farms at Mountlucas in Co. Offaly and Bruckana on the Kilkenny/Laois/Tipperary border respectively. Both these farms are currently under construction and are on sites similar in nature to the Oweninny site consisting of cutaway and cutover peatland areas. As a responsible and environmentally compliant company, one of Bord na Móna Energy Limited s primary objectives is to ensure that proposed developments have minimal environmental impact. Bord na Móna is committed to the highest health, safety and environmental standards in the development and operation of Oweninny Wind Farm. Bord na Móna Energy Limited is also the landowner of the proposed wind farm site THE SITE The site is located in North Mayo, approximately 8.9 km west of Crossmolina and 7.3 km east of Bangor Erris (see Figure 2.1). It is located just north of the N59 road and comprises some 50 km 2. The L52925 local road runs through the centre of the site, the L52926 is located to the west of the site and the L5292 is located to the east of the site. The site is irregular in outline and extends in an east west direction for some 11km and in a north south direction some 7.4km. It comprises two distinct areas divided almost entirely by a narrow strip of private land holdings but is linked by an internal bridge, within the ownership of Bord na Móna, over the Oweninny River. Bord na Móna was involved in industrial scale peat production operations at the site for half a century to supply the ESB Bellacorick peat burning power station. Peat production commenced in the 1950s and peat operations ceased in 2005 following the closure and the power station which was subsequently decommissioning. The site lands are owned by Bord na Móna and comprise cutover and cutaway bog land. Project Description 2.3

7 Peat harvesting operated under an Integrated Pollution Prevention and Control License (IPPC License Number 505) issued by the Environmental Protection Agency (EPA). In accordance with the licence for the site a bog rehabilitation programme has been developed and implemented to enhance rehabilitation of parts of the site. Those parts of the bog that were not harvested by Bord na Móna, known as bog remnants, and bog rehabilitation areas will not be significantly affected by the proposed wind farm development and the wind farm will be integrated into the bog rehabilitation already underway. The site encompasses Lough Dahybaun, a Special Area of Conservation (SAC) protected under the EU Habitats Directive. The Bellacorick Iron Flush SAC is also located within the site boundary. This flush area is owned by An Taisce and by the National Parks and Wildlife Service of the Department of the Arts, Heritage and the Gaeltacht. A large area, approximately 3.6 km 2, known as O Boyles Bog is located within the north-western portion of the site and although within Bord na Móna ownership no development will take place there. The Sheskin stream forms its southern boundary. The Oweninny River drains the central part of the site. The Oweninny river is fed by the Srahmeen river and Knockmoyle Stream from the west and by numerous small tributary streams from the east (Fiddaungal, Fiddaunnaglogh, Fiddaunnameenabane, Fiddauncam and the Fiddaunnamuinggeery) before entering the Oweninny wind farm site. The Owenniny is joined by the Sheskin Steam which drains the forested south-eastern slopes of Slieve Fyagh and also forms the site s internal boundary with the O Boyles Bog area. The Oweninny and the Fiddaunnamuingeery form part of the site boundary. The Sruffaunnamuingabatia, which drains the Bellacorick Iron Flush SAC area within the site, flows westwards and joins the Oweninny river. The Oweninny is also joined by the Muing River which drains Lough Dahybaun within the site. The Owenmore drains a catchment of approximately 332 km2 before entering the sea at Tullaghan Bay. The Oweninny flows southwards, externally to the site and effectively dividing the site in two before joining the Owenmore turning westwards after Bellacorick Bridge and paralleling the N59. The Owenmore is joined at this location by the Altanabrocky river flowing northwards from the Nephin Mountains. The north-eastern part of the site is drained by small tributaries (Fiddaunfura) which rise in Shanvodinnaun and flow eastwards to the main easterly flowing river, also named the Owenmore. This river rises in the townlands of Cluddaun and Shanetra to the north of the site before flowing eastwards becoming the Cloonaghmore River before entering the sea at Rathfran Bay which is within Killala Bay. It is also referred to as the Palmerstown River. The Cloonaghmore River drains a catchment of approximately 132 km2 before entering the sea at Rathfran Bay. The south-eastern part of the site drains to tributaries of the Shanvolahan River (Fiddaunagosty, Shanvolahan and Fiddauntooghaun) before entering the Deel River which drains to Lough Conn and eventually joins the River Moy at Ballina before entering the sea at Killala Bay. The River Moy drains a catchment of approximately 1,966 km2 before entering the sea at Killala Bay. The area of the Shavolahan catchment before it enters the Deel River is approximately 23.7 km2. The site encompasses some 352 hectares of Coillte forest plantation, on Bord na Móna owned lands, comprising mainly Sitka Spruce and Lodgepole pine. This is located mainly around and to the northwest of Lough Dahybaun. The site also encompasses 192 hectares of private forest plantation land at Corvoderry. This area has received planning Project Description 2.4

8 permission for a wind farm development in 2012 (Planning File Reference 11838) and has a right of way through the Bord na Móna lands. The N59 (Ballina to Belmullet) National Primary Road runs immediately adjacent to the southern site boundary. Bellacorick village is located on the N59 towards the south centre of the site with a local road (L52925 or Srahnakilla road) running north through the site in parallel to the Oweninny River. To the west a local road (L52926) runs north off the N59 near Ballymonnelly Bridge for a short distance to Tawnaghmore townland becoming the Western Way, passing Sheskin Lodge and veering north by northeast. To the east a local road (L5292) runs northwards from the N59 to the townlands of Shanvolahan and Formolye. The site is bounded to the north by the Knockmoyle Nature Reserve, part of the Bellacorick Bog Complex csac and by Coillte forest plantation land to the north-east and north-west. The Coillte land to the north-east is also subject to a proposed wind farm development, Cluddaun wind farm, comprising 48 wind turbines. Access to the Cluddaun site will occur off the N59 and through the internal Oweninny access track network to the boundary of the Coillte lands Access to the Oweninny site will occur at three existing site access locations off the N59, an existing access to the Bord na Mona maintenance facilities at Bellacorick, the existing Bellacorick Wind Farm access and an existing access to the Bord na Móna lands at the western part of the site. The altitude of the site is approximately 100m above sea level. All turbines will be located within the site on areas of worked peatlands. The overall area of the subject site is approximately 5,090 hectares (ha) excluding the Bellacorick Iron Flush and Corvoderry wind farm site located within the site boundary with the development occupying approximately 278 ha of this. This is equivalent to 5.4 % of the overall lands, including borrow pit, gravel storage areas and peat repository. Excluding these elements the development (buildings, turbines, hardstands and access tracks) comprises 4.0% of the site. Map on which the site appears is Ordnance Survey (OS) Discovery Series (1:50,000) Sheet No PROJECT HISTORY Planning at Oweninny Table 2-1 outlines the planning history at Oweninny Table 2-1: History of planning at Oweninny Planning Permissions Date granted Authority Comment P90/ Mayo County Council Bellacorick wind farm 21 turbines P92/ Mayo County Council Wind Farm control building Mayo County Council Bord Gáis Eireann Temporary site compound associated with the construction of the Project Description 2.5

9 Planning Permissions Date granted Authority Comment Galway Mayo gas pipeline P01/ Mayo County Council 01/ Mayo County Council PL An Bord Pleanála P12/ Mayo County Council 3 x 50m high wind measuring masts 210 wind turbines decision appealed Granted on appeal 180 wind turbines Retention of 4 temporary meteorological masts Mayo County Council granted permission for 21 wind turbines on the site (Planning Authority Ref. P90/1077) which was subsequently developed as the Bellacorick Wind farm. This comprises 21 turbines located within the site and was Ireland s first commercial wind farm. It has operated successfully since 1992 with an installed capacity of 6.45 MW. Twenty of these turbines are rated at 300 kw and the other is rated at 450 kw. The total output of this existing wind farm is sufficient to meet the needs of approximately 3,000 households. Bord na Móna has operated and maintained the wind farm since its commissioning and is the majority shareholder since The 300 kw turbines are 46.5m high to the uppermost tip of a vertical blade, while the 450 kw turbine is 53.5m high to the uppermost tip of a vertical blade. The spacing of the turbines varies somewhat and is typically 235 m. If it is still operating at the time, this existing wind farm will be decommissioned and new turbines forming part of the final phase of the Oweninny Wind Farm project will be installed near where the existing turbines are located. Permission was also granted for a wind farm control building on the site (Planning Authority Ref. P92/355). In 2002 permission was granted to Bord na Móna Energy Ltd. for the erection of 3 no. 50 metre high wind measuring masts at Corvoderry, Laghtanvack, Srahnakilly, Bellacorick, Co. Mayo (Planning Authority Ref. P01/2826). The permission was granted for a period of three years. The decision was appealed by Bord na Mona Energy Ltd. but the appeal was subsequently withdrawn in July, 2002 (Appeal Ref. PL ). A planning application (Ref 01/2542) was lodged with Mayo County Council on 31st October 2001 for 210 wind turbines including 14 kilometres of 110 kv transmission lines at Corvoderry, Bellacorick, Co. Mayo. The maximum hub height of wind turbines was indicated as 65m with a maximum blade tip height of 100m. On 19th December, 2001, the planning authority requested further information on 50 issues. A response to the request, dated 13th August, 2002, was submitted to the planning authority from the applicant. On 10th October, 2002, the planning authority requested clarification on eight of the items of further information. A response to the clarification request was submitted on 30th May, On 7th July, 2003, the applicant submitted an analysis report to the planning authority on a further water sample from a trial well for a potable water supply. Project Description 2.6

10 Planning permission was granted by Mayo County Council on the 28 th July 2003 subject to a schedule of 43 conditions. Mayo County Council s grant of permission was appealed both by Bord na Móna Energy Ltd. and by third parties to An Bord Pleanála, which subsequently granted planning permission (Ref. PL ) in December 2003, having regard to the following reasons: the national policy with regard to the development of sustainable energy sources; the guidelines issued by the Department of the Environment and Local Government in 1996 on Wind farm Development; the general suitability of the site for a wind powered electricity generating facility due to the wind resource available and the existing land uses including wind farm use on part of the site; the nature of the landscape; the location of suitable ESB apparatus for power connection; the available infrastructure associated with the existing wind farm; and the separation distance of the proposed turbines from inhabited dwellings Planning permission was granted subject to a schedule of 15 conditions. An Bord Pleanála considered that subject to compliance with these conditions the development would not seriously injure the visible amenity or landscape character of the area, would not seriously injure the amenities or property values of residential properties or farms in the vicinity, would not be prejudicial to public health or be otherwise contrary to the proper planning and development of the area. One of these conditions (Condition 4 (a)) reduced the number of turbines proposed from 210 to 180. The remaining turbines were required to be located such that they were: not within 100m from the site boundary without written consent of adjacent landowner to ensure a minimum separation distance of at least 1000m from any occupied dwelling 200m from any designated conservation area 100m from the Oweninny and Owenmore Rivers and their primary tributaries to ensure access tracks, power lines and associated poles and pylons to be a minimum 200m distance from any designated conservation area and 100m from the Oweninny and Owenmore Rivers and their primary tributaries Condition No.1 in An Bord Pleanála s grant of permission provided a limit of 10 years on the duration of permission. Section 40 Subsection (2) of the Planning and Development Act 2000 provides that the appropriate period normally applying in respect of commencement of a development and completion of substantial works does not apply to a permission granted for a limited period. Thus, permission Ref. PL remains in place. Permission was also granted for a period of 20 years from the date of commissioning of Project Description 2.7

11 the final phase of the wind farm. An application for Planning Permission (Ref. No.P12/554) was made in October 2012 by Oweninny Power Limited in respect of retention of four existing meteorological masts at the site, three 50 metre high guyed meteorological masts and one 80 metre high guyed meteorological mast fitted with anemometers and wind vanes. A request for further information relating to an archaeological assessment at the four meteorological mast sites was issued by Mayo County Council on November 20 th A grant of permission was issued in February Delay in Grid Connection For a variety of reasons, most of which have been beyond the control of the developers, the approved development has not proceeded to the construction phase. The delay in advancing the project arose largely from a moratorium on processing applications by wind farm developers for connections to the National Electricity Network. Operation of a wind farm requires a suitable connection to the national electricity grid for export of power generated. The national grid plays a vital role in the supply of electricity. In simple terms, it transports power from generators to demand centres using a system comprising 400 kv, 220 kv and 110 kv networks. The moratorium on processing applications was introduced in the same month that planning permission was granted for Oweninny Wind Farm in 2003, when the Commission for Energy Regulation (CER) instructed the Transmission System Operator (TSO) and the Distribution System Operator (DSO) to cease issuing new connection offers. This instruction was made in response to concerns about the grid stability implications of the scale of proposed wind generation. In addition to halting the issuing of new offers, the moratorium caused an acceleration in the number of applications for connection agreements for wind capacity. Applications increased by more than fourfold in the 10-month period from the start of the moratorium and its continuation partly arose from the difficulty presented by the challenge of processing the large number of wind farm connection applications. A key difficulty related to the interactions between connections, i.e. one connection has an impact on another. A Group Processing Approach, known as the Gate Process, was subsequently adopted for applications that had been submitted prior to the moratorium and modifications of this were also applied to applications received after the moratorium was introduced. Essentially, applications remained in a queue following CER s instruction to process, in application date order, the wind farm connection applications. Wind farm connections were granted in the Gate 1, Gate 2 and Gate 3 process. Oweninny Wind Farm project is amongst those processed as a Gate 3 application and has received grid connection offers totalling MW. Of this 172 MW will be connected to the existing Bellacorick 110 kv substation and the existing overhead lines will be upgraded by EirGrid for this purpose. The remaining MW is proposed to be connected to a new 400 kv substation and transmission system to be provided by EirGrid under the Grid West project Duration of Permission Offers of grid connection for Oweninny Wind Farm have now been received by Oweninny Power Limited. Offers for 172MW of capacity have been executed and this capacity is scheduled to be available at the end of However, the date of actual availability of Project Description 2.8

12 the connection for the remainder of the capacity, and thereby the construction of the final phase of the wind farm will depend on the delivery of EirGrid s Grid West project. The grid is planned and developed to ensure it meets projected transmission needs while maintaining its performance within defined reliability standards. To continue to meet standards, in the context of forecast demand and new generation connections, there is a requirement for ongoing development to reinforce the grid. It is not possible to achieve construction of all phases of the proposed development within the normal lifetime of a grant of planning permission (5 years) given the scale of the project and the scheduled grid upgrades. Given the scale and element of uncertainty in grid scheduling a duration of fifteen years is being sought for any planning permission issued on foot of this application. An operational lifetime of 30 years is been sought for the proposed wind farm following commissioning. These difficulties are recognised in the DoEHLG Wind Farm Planning Guidelines 2006 (Section 7.20) where the following is stated: Planning authorities may grant permission for a duration longer than 5 years if it is considered appropriate, for example, to ensure that the permission does not expire before a grid connection is granted. The above is also referenced in the DoEHLG Circular Letter PD 3/08: Wind Energy Development Planning Permission and Grid Connections, where the following is stated: Authorities are reminded of the powers currently available to them under Section 41 of the 2000 Act to specify a period of more than 5 years during which permission is to have effect. This provision could be a means of providing the necessary flexibility, in respect of new developments, and having regard to the nature and extent of the relevant development, to allow for proper sequencing of permissions and grid connections Integrated Pollution Prevention Control License Bord na Móna has been issued with an Integrated Pollution Prevention Control (IPPC) Licence by the EPA (Registered Licence Number P see Appendix 2) with respect to the: Principal Activity Class Minerals and other materials and described as The extraction of peat in the course of business which involves an area exceeding 50 hectares Condition 10 relates to Cutaway Bog Rehabilitation and requires Bord na Móna to develop and implement a bog rehabilitation plan for the permanent rehabilitation of the cutaway bog lands within the licensed area. This plan has been prepared and approved by the EPA and is now at the completion stage (copy of plan attached in Appendix 3). Peat harvesting activities ceased in 2003 with associated peat haulage activities ceasing in 2005 and there is now no licensable activity occurring on the Oweninny site. Bord na Móna is in the process of surrendering the IPPC licence. The bog rehabilitation programme of activities is now substantially complete and natural rehabilitation is underway. The overall site development for the wind farm will be carried out in a manner that will both integrate with the bog rehabilitation programme and complement and Project Description 2.9

13 enhance it DESCRIPTION OF SCHEME Scheme Components The development will generate electricity by harnessing the wind and will supply the power to the National Grid. The development will consist of a maximum of 112 wind turbines, each of approximately 2,500 3,500 kw rated capacity. It is anticipated that the project will generate between 1,095, 1,200, Gigawatt hours (GWh units) of electricity per annum. The capital costs of the proposed development are projected to be in the order of up to 600M. The main components of the scheme are wind turbines, access tracks, four Electrical substations containing electrical control buildings and substation, an operation and maintenance building, a visitors centre, two 110 kv overhead lines with pole sets and angle masts, underground cables and eight permanent meteorological masts. The layout of the site can be seen in Figure 2.1. The wind farm components will occupy a very small part of the Bord na Móna lands at Oweninny (278 hectares or 5.4%, including borrow pit, gravel storage areas and peat repository. Excluding these elements the development comprises 4.0% of the site). The remainder will be available for existing or other uses. The currently approved development comprises 180 wind turbines arranged in a fixed linear pattern. The geographic spread of the new development adopts a non linear pattern to maximise energy yield from the site. The rehabilitation process on the site has resulted in ground cover that largely screens any view of the former peat harvesting operations drainage network within the site. Therefore the previous rationale for the layout to reflect the regularity of the drainage network no longer exists on the site Wind Turbines The turbines will have a maximum base to blade tip dimension of 176 m. This will likely comprise a tower height in the range m and three blades, each with a blade rotor diameter in the range of between m, i.e. turbines may be configured as comprising a tower/blade configuration within these ranges, with a maximum tip height of 176m. The currently permitted development has an overall dimension of 100 m and the increased overall dimensions reflect the technical developments that have taken place in wind turbine design since preparation of the original planning proposal in The increased dimensions allows for greater flexibility in choice of turbines by the inclusion of a significantly larger number of candidate turbine models. It also facilitates greater sustainable capture and deployment of Ireland s prime renewable energy source. The wind turbines, a typical view of which is shown in Figure 2.2, will be selected from a range of models that have been demonstrated successfully throughout Europe and certified to the highest international standard. The contract to supply and construct the wind farm will be open to international competition under international procurement rules Project Description 2.10

14 to which both ESB and Bord na Móna are subject. For this reason it is not possible to specify the exact turbine which will be deployed at Oweninny but it will be within the range indicated. While the choice of make and model has not yet been finalised, the wind turbines under consideration for installation are three bladed, horizontal axis machines. There are a number of candidate machines, with those indicated in Table 2-2 being typical. However, turbines of larger rating will also be considered for the site within the overall height envelope of 176m. The turbine towers will be either of tubular steel design or hybrid concrete/steel tapering from about 4.5 m diameter at the base to about 3.2 m diameter at the top where the nacelle will be mounted. A three blade rotor will be attached to the nacelle. The blades will be made of fibreglass-reinforced epoxy material with each blade typically consisting of two blade shells, bonded to a supporting beam. Table 2-2: Candidate Wind Turbines* Model Rating (MW) Hub Height (m) Rotor Diameter (m) Overall Dimension (m) Alstom Enercon E GE 2.5xl Nordex N Nordex N100/ Siemens Vestas V Vestas V *Note this is not an exhaustive list of turbines The nacelle will contain the generator and control unit, which will be designed for computer controlled monitoring of all major functions of the turbine. It will have effective sound insulation and smooth performance of moving parts will ensure minimal noise. The components of a typical nacelle are shown in Figure 2.3. The steel tube towers with high specification, factory applied, paint finish will be fixed to concrete bases, the exact depth and structural design of which will depend on site conditions and may vary slightly from one turbine to another. An alternative tower type which is becoming available consists of concrete/steel construction. These can offer advantages where transportation constraints are identified as concrete towers could be delivered in small precast concrete sections which could be assembled on site. Two types of wind turbine foundation are envisaged as follows: For turbines located on good ground bearing stratum the turbine foundation will be either circular or hexagonal shape with square dimension of approximately 22m. For the purpose of planning foundation with hexagonal design have been shown. For turbines on difficult ground or within proximity of sensitive areas with high Project Description 2.11

15 dependence on ground water, turbine foundations will be piled. Piles will be reinforced concrete of approximately 900mm diameter and with an average length of 17m. Detailed geotechnical investigations will be undertaken at the site prior to commencement of construction to enable detailed structural design of foundations. Access to the turbine is via a staircase located outside on the hardstand and a secure hinged door into the tower. Personnel access in the turbine towers and nacelles will meet all safety regulations. The equipment will be protected from lightning strike by deep earthing and from corrosion by multiple coatings. All wind turbines are located at minimum distance of 1000m from the nearest dwelling, are at least 100m from the site boundary, 200m from designated areas and 100m from major rivers and their primary tributaries. Method of Operation The basis of wind turbine operation is as follows: A yaw mechanism turns the turbines so that they face the wind. The wind forces the blades of the turbine to rotate. The rotation of the blades rotates a generator within a nacelle (housing) located at the turbine hub to produce the electrical power output. The electricity generated in the nacelle is fed via cables in the tower and subsequently underground to electrical transformers where it is transformed to a higher voltage for supply to the National Grid. Sensors will be used to monitor wind direction and the nacelle will yaw to keep the blades facing into the wind. The turbine blades will rotate at about one revolution every 3 5 seconds, depending on wind speed. The turbines will have active pitch regulation whereby the angle of the rotor blades can be adjusted by the machine control system. This system has built-in braking, as the blades become stationary when they are fully 'feathered'. The turbines will commence operation at a wind speed of about 4 m/s, will attain maximum output at about 15 m/s and will shut down when the wind speed reaches a 10-minute average of 25 m/s. Power will be controlled automatically as wind speed varies. Locations The wind turbines will be located at elevations in the approximate range m OD. Details are as shown in Table 2-3. An initial layout of 124 wind turbines was considered for the site and this was subsequently reduced to 117 turbines, based on the constraints identified arising from the planning conditions set out by An Bord Pleanála (Ref. PL ). The layout showing 117 wind turbines formed the basis for consultation purposes with key stakeholders (Scoping exercise). The final layout of 112 turbines was arrived at on the basis of this consultation and on the basis of hydrogeological, geotechnical, ecological and cultural heritage investigations on site. Further detailed investigation at the time of construction may lead to minor repositioning of a small number of individual turbines, as described in the DoEHLG Windfarm Planning Guidelines (Section 5.3). Provision must be made for carrying out site-specific geo-technical investigations in Project Description 2.12

16 order to identify the optimum location for each turbine. These investigations may suggest minor adjustments to turbine location. In order to accommodate this practice there should be a degree of flexibility built into the planning permission and EIS. The extent of flexibility will be site specific but should not generally extend beyond 20 metres, The stochastic layout lends itself to micrositing of turbines if this is required. Avoidance of deep peat, bog remnants and maintaining the set back distances proposed for the development overall will be the key objective of any turbine micrositing. In the event that a requirement for minor changes arises, the final layout will be agreed with the Planning Authority before commencement of construction. Any suggested micrositing will be subject to the constraints that it does not lead to greater visual prominence of overall development and that a minimum separation of 1000 m from the nearest occupied residence is maintained. Project Description 2.13

17 Table 2-3: Locations of Turbines No. Easting(ITM) Northing (ITM) No. Easting (ITM) Northing (ITM) No. Easting (ITM) Northing (ITM) T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T Project Description 2.14

18 Northing No. Easting(ITM) Northing (ITM) No. Easting (ITM) Northing (ITM) No. Easting (ITM) (ITM) T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T Project Description 2.15

19 Note: Coordinates in ITM. Project Description 2.16

20 2.5.3 Transformers A separate transformer will be associated with each wind turbine to step up the generation voltage of the turbines from V to a higher voltage for connection to the electrical substation via underground cables. In modern wind turbines in the range of sizes under consideration, the transformer is most commonly located within the nacelle or turbine tower. However, depending on the turbine manufacturer, for safety reasons, it may be located outside of the tower close to the base. Where not accommodated within the wind turbine, it is not feasible or good practice from a safety perspective to locate the transformer underground. Rather, it will reside within a compact glass-reinforced plastic or steel enclosure measuring approximately 2.5 m x 2.5 m in plan and approximately 2.2 m high. The enclosure will also contain a ring main unit (RMU) switchgear complete with feeder circuit-breaker and close over-current / earth-fault protection. The hermetically sealed wind turbine transformers, likely contained within the wind turbine tower or otherwise located close by, can be considered as leak free and maintenance free. They are dispatched from the factory leak free and can only be damaged during transport or installation. Once in service, they remain closed for their lifetime Site entrance Access to the site will be off the N59 Ballina to Belmullet road. There will be three site entrances as follows: Entrance 1: Existing Bellacorick wind farm entrance Entrance 2: Existing access to the western part of the site Entrance 3: Existing Bord na Móna workshop location entrance The locations of the proposed access points to the site are shown on Figure Access Tracks Access is required to facilitate construction of the turbine bases and erection of the turbines. Access tracks, which will be un-surfaced, will be constructed directly on the underlying firm material. There is an extensive network of existing tracks within the site comprising an existing access track to the existing Bellacorick wind farm, access track to former farm buildings within the site and access track ways formerly used as railway beds in the peat operations which took place on site. All railway track was removed from the railway beds as part of the rehabilitation process. Where possible the existing access tracks have been incorporated into the development to the extent possible. Peat probing along the proposed access routes to turbine locations was undertaken to identify the optimum route along corridors of minimal peat depth and also avoiding very wet areas of the site. The tracks provide access to points relatively close to all turbine locations, each of which can be accessed without major constraints of poor ground, steep inclines or significant watercourses. The existing tracks, of which use will be made, will be strengthened and widened and new sections will also be constructed. Approximately 85km of access tracks will be required in total. Tracks will be approximately 5.5m wide with passing bays provided at appropriate locations and horizontal bend radii designed and constructed to accommodate the Contractor s Project Description 2.17

21 transport equipment. Access track depth will vary depending on the depth of peat to bearing stratum and bearing capacity of the underlying soils. Peat depths along proposed access track routes were probed to identify optimum routes across shallow peat depth areas. Resulting from this approximately 70km of access track will be constructed on shallow peat areas with a dimension 5.5m x 0.8m built on the bearing stratum. Excavated peat material will be side cast adjacent to the access tracks and dressed to blend in with surrounding landscaping and partially obscure sight of the road where feasible. The remaining 15km of road will be constructed over deeper areas of peat. These will be constructed either as floating access tracks or by excavating and backfilling. Construction of the access tracks in these areas will require excavation to an average depth to bearing stratum of 2.0m. Excavated peat will either be sidecast where feasible or removed and deposited in the peat repository area located in the centre of the site. The access tracks will require a cambered top surface to assist the drainage of rainwater to either side of it. A site drainage plan has been developed to manage surface run off from the access tracks and cranepads, turbine locations and other structures associated with the development. Existing access tracks to be incorporated: 6 km Additional access tracks to be provided: 79 km The layout of the additional access tracks has been developed to follow the natural contours of the site, to avoid areas of deep peat and very wet areas and to minimise their overall length and achieve acceptable gradients. The latter are expected to be a maximum of 8 (14%) longitudinally and 2 (3%) laterally. All power and control cabling within the site will be either direct buried or contained in PVC ducts and will be laid underground. Cable trenches, which will typically be m wide and m deep, will generally follow the edge of the site access tracks and will be installed in conjunction with the tracks Access to Coillte Teoranta s Cluddaun proposed wind farm site The proposed Cluddaun wind farm development is located to the northeast of the Oweninny site and Bord na Móna and Coillte share a common boundary in this location. To reduce disruption on non primary roads near the Cluddaun entrance and as requested by Mayo County Council, access to the proposed Cluddaun wind farm site will be provided via the Oweninny internal access track network from the N59. An access track spur to the Coillte property is provided in the design near turbine location T5 (see Figure 2-1). The cumulative impact on traffic and transport is discussed in detail in Chapter Crane stands A triangular shaped cranepad comprising a hardstanding area will be provided adjacent to each wind turbine to facilitate construction. They will be retained for the lifetime of the wind farm to facilitate any large scale maintenance involving the use of a large crane that could arise during the operational phase of the wind farm. The dimensions of the cranepad will be approximately 96 m x 76 m x 130m. The crane stand will be constructed adjacent to the access trackway beside each turbine and will comprise an area of approximately 3,600m 2. It will accommodate the main crane (1,200 ton capacity) and the assist crane which will be used to erect and dismantle the main lifting crane. It will also accommodate the tower and nacelle components prior to construction. Adjacent to the crane pad an area of 16m x 33m will be provided on either bogmats or hardstanding to Project Description 2.18

22 support fames in the blade laydown area. The main crane will lift turbine blades from this area to the turbine nacelle. The various turbine suppliers have differing requirements as to the arrangement and orientation of the cranepad relative to the position of the turbine. The likely arrangement is shown on the project drawings, (see Planning Drawing QR P ) but the actual orientation will be a matter to be agreed with the selected turbine supplier Electrical Substation Four 110 kv Electrical Substations at the site will occupy an L shaped hard-standing area of approximately 8853m 2 and will consist of a compound containing outdoor switchgear comprising a 110 kv busbar, one 110 kv line bay, two 110/33kV transformers and associated bays, house transformer and 2 Control Buildings. The substation footprint will be such as to allow for the inclusion of two additional transformer bays. These additional areas are required by EirGrid, the National Transmission Operator, to futureproof the requirements of Grid 25. The layouts of the Electrical substations are shown in the planning drawings (see Planning Drawings QR P to QR P ). Substation locations are provided in Table 2-4. Table 2-4: Electrical Substation Locations (Centre point) Sub Stations Easting_ITM Northing_ITM Sub Station Sub Station Sub Station Sub Station Equipment within each control building will include a Supervisory Control and Data Acquisition (SCADA) system, which will allow for off-site monitoring via a telephone or fibre optic connection. Each control building will be designed to the standard required for the accommodation of sub-station equipment. Each will comprise a control room, relay room, switchgear rooms, battery rooms and store room. It will be single storey, approximately 25 m x 9 m in plan. The control buildings will have rough-cast walls and a pitched roof with tiles or slates. Each control building s appearance will be in keeping with its location. The control buildings will be unmanned, but will include sanitary facilities comprising a single toilet and wash hand basin. Surface water arising from roof drainage will be allowed to percolate naturally within each Electrical substation compound. Each substation within the electrical substation will further step-up the voltage for transmission to the national electricity network. Electrical equipment will consist of a transformer, circuit breaker, over-current and other protection devices, metering equipment and other small items of switchgear. Each Grid Transformer will be located within an impermeable bund capable of oil Project Description 2.19

23 retention in the event of a total leakage from the transformer. The bund will have a capacity of at least 110% of the volume of oil to preclude any release of contaminants to the environment. Drainage arising from the transformer bund will be discharged following passage through an appropriate oil interceptor. Permanent 2.6 m high palisade fencing, the colour of which will be agreed with the planning authority prior to construction, will be provided around each electrical substation for public safety purposes. This need arises from the presence within each compound of high-voltage electrical equipment to which public access must be prevented. Access to the site and to the turbines within it is safe for people and animals under normal conditions Meteorological masts Meteorological masts with a height corresponding to that of the turbine hubs are normally included in wind farm developments in order to monitor wind speeds and validate operation of the wind turbines. Permission was granted to Bord na Móna Energy Ltd. for the erection of 3 no. 50 metre high wind measuring masts at Corvoderry, Laghtanvack, Srahnakilly, Bellacorick, Co. Mayo (Planning Authority Ref. P12/554). These were used to capture the initial data required for wind analysis purposes. An application to retain these structures, and an 80m high mast installed in 2011, was made in October 2012 to continue data capture. Permission for retention was granted in February These meteorological masts will be replaced by eight permanent meteorological masts on the site. The locations of these are shown in Table 2-5. The overall separation between the outermost turbines at Oweninny is such that variation in wind speeds across the site would be expected. Thus, given the scale of the site eight meteorological masts are proposed with each comprising a lattice steel tower with anemometers and wind vanes attached. The overall height will approximately correspond with the tower height of the turbines, i.e. a maximum of 120m. Occasionally other equipment such as noise monitoring equipment may be located near to ground level on the meteorological masts Table 2-5: Meteorological Mast Mast Townland Easting ITM Northing Location 1 Tawnaghmore Location 2 Srahnakilly Location 3 Croaghaun West Location 4 Moneynierin Location 5 Laghtanvack Location 6 Knockmoyle Location 7 Laghtanvack Project Description 2.20

24 Mast Townland Easting ITM Northing Location 8 Shanvodinnaun Further to the above, power curve testing will be carried out at a number of turbine locations within the site. Power curve testing comprises site calibration and reference, and entails temporary installation of anemometer masts for selected turbine sites at two locations, a calibration mast corresponding to the location of a turbine and the reference mast elsewhere within the site. The data generated is used subsequently to validate the contracted performance of the wind turbines. Evidently, the masts at the location of the selected turbines will be removed to allow construction of that turbine in the wind farm development and the other mast will also be removed prior to completion of the development Overhead Transmission Lines and Underground Cables Connection of the wind farm to the National Grid will occur in phases in line with the phased development of the project. Phase 1 and Phase 2 of the project will connect to the existing 110 kv Bellacorick substation and will export power via the existing 110 kv overhead line infrastructure, which will be strengthened by EirGrid. Phase 3 of the project will connect to a new proposed EirGrid 400 kv substation whose location is not known at this time. Power from this phase will be exported via 110 kv lines to connect to the new 400 kv infrastructure to be provided by EirGrid. EirGrid is in the process of identifying a suitable location for the 400 kv substation and a suitable route for overhead lines or possibly underground cables as part of the Grid West project ( Any proposed site and route will most likely be considered as strategic infrastructure development and will be subject to a full planning and environmental approval processes. Within the wind farm, clusters of wind turbines will be connected via underground cables to the four 110 kv substations. The route of two of these 110 kv lines from substation location 1 and substation location 2 will connect to the existing Bellacorick 110 kv substation. The 110 kv line routes for substation 3 and substation 4, both of which will be developed under Phase 3 of the project cannot be indicated as the location of the EirGrid 400 kv substation to which these will connect is unknown at this time. Once the location of the EirGrid 400 kv substation receives planning permission two 110 kv routes will be developed and approval sought from the planning authority, if required. To minimise the potential visual and landscape impact the overhead line from substation locations 1 and 2 will be undergrounded as it approaches the Bellacorick substation site for a distance of up to 2km. A cable interface tower will be utilised as a transition structure to accommodate the transition from overhead line to underground cable. A cable interface tower has the same dimensions as the normal angle tower though additional hardware is added to accommodate the cable / line transition. The overhead lines and underground cable routes are shown on Figure 2-1. Cables routes from the eastern part of the site will be ducted across the Bord na Móna internal bridge across the Oweninny river which will be fitted with a new deck, see Planning Drawing Number QR P Project Description 2.21

25 This approach is consistent with the Department of Environment Wind Energy Development Guidelines 2006 which states the following in Section : Power line connections between turbines and from turbines to the control building should be underground. Power lines should be interred alongside turbine access roads in order to minimise spatial extent of soil/hydrological and vegetation damage/ disturbance. The cost of underground connection from the compound to the national grid is generally prohibitive. This connection can thus be above ground in all but the most sensitive landscapes. In certain landscapes, such as highly sensitive Mountain Moorland, consideration should be given to burying the cables until such a distance as the poles and cables would be visually acceptable, for example, where other power lines exist. In order to reduce visual impact, connections should preferably be carried on wooden poles rather than lattice towers, except where necessary for changes in direction and within the compound. Power line connections to the grid should, where possible, avoid running perpendicular to contours, especially on Mountain Moorland slopes. Where practicable, it should not cross the horizon at ridge level unless a line already exists. Where passing through a forest, power line connections should follow existing firebreaks or roads. In landscape types where human presence and rectilinear landscape patterns are typical, power line layout can be more flexible. Each 110 kv overhead line will consist of three overhead conductors carried on double wood pole portal structures, whose poles are 5m apart (centre to centre) and average height of 18 metres. The pole structures will have a maximum height of up to 22 m. The average distance between structures will be approximately 180m. An earthwire, consisting of two continuous wires, will be clamped to each set of wood poles and steel lattice towers. Where the line changes direction, a steel lattice angle tower up to 24.5 m in height and an average base area of 5m x 5m will be utilised. Typical overhead line structures are shown in Figure 2-5 and on Planning Drawings QR P to QR P Visitor Centre The proposed development offers an ideal opportunity to relate the socio-economic and ecological history of the site and general area thorough a purpose built visitor centre. Both Bord na Móna and ESB have had long association with the area dating from the 1950 s. Bord na Móna has been involved in peat production operations at Oweninny to fuel the ESB peat burning station at Bellacorick (see Plate 2-1). This provided not only electricity but much needed employment in a traditionally economically deprived area. Project Description 2.22

26 Plate 2-1: Bellacorick power station With the closure of the power station in 2005 peat operations also ceased. Emerging wind energy technology was seen as a logical natural replacement for peat based energy production which could continue to give gainful employment in the area. The site itself plays an historical role in Ireland s drive towards sustainable renewable energy with the country s first commercial wind farm established at the site in It comprises 21 wind turbines with a total installed capacity of 6.45 MW (Mega Watts), and produces enough electricity to supply approximately 3,000 households. This wind farm, if still operational, will be replaced in the final stages of the planned development. The site also relates an interesting ecological story. In accordance with its Integrated Pollution Prevention Control licence for the site Bord na Móna has developed a bog rehabilitation programme to enhance recovery of parts of the site. The harvesting operations and rehabilitation programme have created a mosaic of differing habitats and species. The ecological history and current status of the bog can therefore be depicted through the bog remnants, bog rehabilitation areas and protected areas and the variety of habitats and species that they support. The visitor centre will offer the unique history of the bog throughout its development showing the transition from peat harvesting to wind energy development. In parallel, the story of the changing ecology of the bog, the ongoing bog rehabilitation programme and the diversity of species and habitats that has resulted will be told. It will provide a place not only to learn about renewable energy but to observe it first hand whilst also providing an opportunity to observe the ecology of the area. The Visitor Centre location is shown on Figure 2-1. Plan and elevation drawings are Project Description 2.23

27 shown in Figure 2-7 and Figure Temporary Site Compound Temporary site compounds will be established throughout the site for the duration of the construction phases. These will comprise temporary construction buildings, materials and equipment storage. The site compound will be segregated into four separate sub compounds to facilitate the likely different contractors expected on site. Typical layouts of proposed site compound is provided in Figure 2-9 and Figure In addition, areas adjacent to substation 2 and substation 4, an area at the western entrance (Site Entrance 2) and an area behind the existing Bord na Móna workshops have been identified as potentially suitable site compounds. However, It will be a decision of the construction contractor as to where the temporary site compounds will finally be located Batching Plant A temporary batching plant for concrete production will be established adjacent to Electrical substation 2 (Figure 2.1). This will comprise the following components: 4 x Aggregate stockpile areas each of approximately 5,000 tons capacity 4 x Aggregate bays 1 x Ramp and feed hopper 2 x Cement Silos 1 x Mixer House 1 x Bunded Additives Store 1 x Control Cabin 1 x Three Bay Water Recycler Water storage area Power House & Switch Room Mobile Plant Refuelling Area Bunded and covered Gas Oil Tank Site office Laboratory Canteen Welfare facilities Parking The batching plant compound will be fenced with chain-link fence. A typical batching plant layout is shown in Figure Drainage control including sediment control and settlement and ph neutralization will be provided at this location. The batching plant will incorporate a three bay water recycling system to minimise water Project Description 2.24

28 usage and loss of suspended solids. The three bay water recycler will be cleaned regularly and any build up of settled solids will be removed to a hard standing area which drains to the recycler and the collected solids will be recycled into the concrete batching system. Water for the batching plant operation will be sourced from local ponds or tankered to the location for storage and use as required. The batching plant will be capable of producing 50m 3 of concrete per hour with a requirement of 10 m 3 of water and 20 tons of aggregate and 5 tons of cement Wastewater treatment facilities Sanitary facilities, such as toilets and wash hand basins will be provided at all substation locations and the operation and maintenance building. The visitor centre will have a full café facility, toilets and other sanitary facilities. These facilities will generate foul wastewater which will be treated before discharge to groundwater. To determine the appropriate level of treatment of this wastewater discharge site suitability assessments have been carried out by a qualified assessor, BK Engineering Design, at the substation and visitor centre locations. The O&M building will share a common treatment system with substation number 1. The assessments were carried out in accordance with the EPA Wastewater Manual - Treatment systems for small communities, Business, Leisure Centres and Hotels and the EPA Code of Practice: Wastewater Treatment and Disposal systems. The site assessments indicated that the ground conditions satisfy all requirements specified in the EPA code of Practice and are suitable for discharge following treatment. The site assessors wastewater treatment system recommended for each location consists of a septic tank followed by a Puraflo system and polishing filter with subsequent discharge to subsoil Borrow pit To reduce the requirement for import of access track construction material to the site use will be made of one borrow pit that has been assessed to contain suitable material. The location of the borrow pit is shown in Figure 2.1. Its footprint is approximately 17 hectares and it will be excavated to a depth of about 2m giving an estimated 340,000m 3 of material for access track construction, sufficient to construct approximately 70km of access tracks with dimension 5.5m x 0.8m. The coordinates of the borrow pit are provided in Table 2-6 Excavated material will be stockpiled in an area adjacent to turbine 37, see Figure 2-1. Peat depths at the borrow pit location are very shallow, being only 100mm in places. This material will be scraped from the surface, stored locally and backfilled into the borrow pit following material extraction Table 2-6: Borrow Pit Location Easting (ITM) Northing (ITM) Project Description 2.25

29 Easting (ITM) Northing (ITM) The top metre of material will be dry extracted and below this the material from the borrow pit will be wet extracted to prevent a reduction in the water table level. That is, there will be no dewatering of the borrow bit as this could impact on the groundwater level with potential to impact the Bellacorick Iron Flush area Bord Gáis Network There is a high pressure Gas Transmission Pipeline running along the south side of the site close to N59 and along the western boundary also. Approximately 2.5km before Bellacorick it enters the wind farm site and continues in the north - west direction. The line route of the gas transmission pipeline is shown in Figure Water supply Potable water for the site will be provided either through a connection to the water supply scheme operated by Mayo County Council, to which both Bord na Móna and ESB have connections, or alternatively through bored wells with subsequent treatment and storage. A bored well, if suitably identified, and/or rainwater harvesting will also be used to supplement the water demand at the substations and proposed visitor centre Electricity supply House supply for the visitor centre, substations, batching plant and O&M building will be provided through the existing supply to the Bellacorick wind farm or from power generated on site River and stream crossings The development of the access track network will require the upgrading of existing river crossings and the construction of new crossing locations over streams. The existing Bord na Móna machine bridge across the Oweninny river will be upgraded to carry electricity cables. There will be no in-river modification works. The culverts at the site entrance on the Muing river will be removed and replaced by a box culvert or clear span bridge. Further crossings using box culverts will take place upstream on the Muing river and on its tributary the Muingamolt. A small existing culverted crossing of the Sruffaunnamuingabatia stream will be replaced by a box culvert or clear span bridge. Replacement of existing crossings with box culverts on small streams near the headwaters of the Owenmore/Cloonaghnore river, the Fiddauntura and the Fiddaunnagosty streams will also take place. Small stream crossings will occur in the headwaters of the small river flowing beneath the Ballymonnelly Bridge into the Owenmore. Stream crossing works will be discussed with Inland Fisheries Ireland and will be carried Project Description 2.26

30 out in accordance with the Requirements for the Protection of Fisheries Habitat during Construction and Development Works at River Sites 1 or any updates as appropriate MATERIAL QUANTITIES Estimates of the material quantities for stone fill, concrete and rebar for each phase of the project are provided in Table 2-7. Table 2-7: Estimates of material quantities Project Phase Material Quantity Phase 1 Fill (m3) 196,153 Concrete (m3) 33,222 Rebar (t) 3,013 Phase 2 Fill (m3) 206,175 Concrete (m3) 30,180 Rebar(t) 2,695 Phase 3 Fill (m3) 334,542 Concrete (m3) 56,430 Rebar(t) 5, PEAT STABILITY RISK ASSESSMENT A Peat Stability Risk Assessment (PSRA) has been prepared for the site. See Appendix 4. The assessment is based on the Natural Scotland Scottish Executive Peat Landslide Hazard and Risk Assessment: Best Practice Guide for Proposed Electricity Generation Developments (2006) supplemented by the experiences of ESBI on previously developed sites. Peat stability risk is categorised as insignificant, significant, substantial or serious. Construction can take place in areas where risk categories range from insignificant to substantial with varying mitigation requirements. The insignificant and significant categories represent areas where the risk of peat instabilities are either considered negligible in a standard construction environment or considered manageable by the adoption of specific additional mitigation measures respectively. In the context of this development, the substantial risk category represents areas where more rigorous site investigation is required prior to construction at detailed design stage, more onerous mitigation measures are actioned and a higher level of site supervision is locally imposed in order to reduce the risk to lower levels. Approximately 80% of the construction area is classified as having insignificant or significant risk. The risk at these areas will be mitigated with good design and construction practices and part geotechnical supervision. The remaining 20% of the 1 Eastern Regional Fisheries Board, Fisheries Protection Guidelines, Requirements for the Protection of Fisheries Habitat during Construction and Development Works at River Sites, Project Description 2.27

31 construction area is categorised as having substantial risk of peat instability, however, in these cases the level of risk is on the lower end of the substantial (i.e. close to the significant risk category) and is suitable for construction with suitable site investigation, good design and construction practices and geotechnical supervision during works in critical areas. No areas are categorised as serious INDICATIVE PROJECT PHASING Phasing The project will be developed in 3 phases which are determined by grid access availability and construction scheduling. The following indicative phase developments will take place, (see Figure 2-12). Phase 1 will comprise the construction of MW of wind energy comprising construction of wind turbines in the central section of the site, associated access tracks, one Electrical substation, substation, overhead lines and cables. The Visitor Centre and Operation and Maintenance Building will also be constructed during this phase. This phase will connect to the existing 110 kv substation at Bellacorick and the construction is expected to commence in 2015 with completion of Phase 1 by Phase 2 will comprise the construction of MW of wind energy comprising construction of wind turbines in the western part of the site, associated access tracks Electrical substations, substation, overhead lines and cables. This phase will also connect to the existing 110 kv substation at Bellacorick and the construction is expected to commence in 2016 with completion of Phase 2 by Phase 3 will comprise the construction of the MW of wind energy comprising construction of wind turbines in the southern, eastern and north-eastern parts of the site, associated roads, Electrical substations, substations, overhead lines and cables. Although a grid offer has been received this construction phase is dependent on the implementation of Grid West by EirGrid which will provide a new 400 kv substation and transmission system in the general Mayo area. Construction of Phase 3 is therefore expected to commence post 2018 with completion around The indicative project phasing is shown in Table 2.7. Table 2.7: indicative Project Phasing Phase Rated Output (MW) Approximate construction period Phase Phase Phase Post 2018 * * The timing of this phase of the development is dependent on the timing of the Grid West development. Actual project phasing will be determined by the nature of any permission granted for the site, the output size of the turbine selected following a full procurement process and the availability of grid capacity. Project Description 2.28

32 2. 9 OPERATION, MAINTENANCE AND DECOMMISSIONING Operation and Maintenance Project Lifetime It is envisaged that the project will remain in operation for about 30 years following its commissioning, although depending on circumstances it may be viable to continue the project for further periods thereafter. The Bellacorick wind farm is in operation at the site for 21 years now and continues to perform well with high availability and turbines maintained in good condition. It is expected to have a useful operating life in excess of 25 years in the same environmental conditions and wind regime as those that can be expected for the Oweninny wind farm. Condition No. 3 in the current planning permission (PL ) for Oweninny Wind Farm limits the life of that development to a period of 20 years from the date of commissioning of the wind farm. It is believed that an operational life of 20 years for a wind farm is overly restrictive in comparison with recent grants of planning permission by various planning authorities and by An Bord Pleanála, which have specified an operational life of 25 years. A lesser operational life of 20 years as opposed to 30 years for other wind farms imposes a commercial disadvantage on this development in comparison with other similar schemes with which this development may potentially be in competition for supply of renewable electricity. The DoEHLG Planning Guidelines (Section 7.20) have subsequently noted as follows: The inclusion of a condition which limits the life span of a wind energy development should be avoided, except in exceptional circumstances. Wind Farm Operation It is expected that the wind farm will have an availability of about 98%, i.e. it will be capable of operation for 98% of the time. Actual operation will be determined by the wind conditions experienced. However, on average, turbines turn and therefore produce electricity for about 80-85% of the time. The output of the wind turbines will depend upon the wind regime but a capacity factor of around 33-35% is expected. This means that over the course of a year each turbine would produce up to 35% of the amount it could theoretically produce if it was working at maximum output at all times throughout the year. Wind farms are designed to operate largely unattended however given the scale of the development a technical staff of up to 10 people initially will be present for monitoring and routine maintenance operation. This number will increase as subsequent phases of the wind farm are developed. Each turbine will have its own in-built supervision and control system that will be capable of starting the turbine, monitoring its operation and shutting down the turbine in the case of fault conditions. Supervisory operational and monitoring activities will be carried out remotely using a SCADA system, with the aid of computers connected via a fibre optic or telephone modem link. Servicing of the wind turbines will be carried out in accordance with the manufacturer s specifications, which would be expected to entail the following: Project Description 2.29

33 Six-month service - three week visit by four technicians Annual service - six week visit by four technicians Weekly visit by Developer or agents to check over the site, notices etc. Occasional technical problems may require maintenance visits by the technical staff. During the six-month and annual service visits, some waste lubricating and cooling oils will arise. These will be recorded, drained into designated storage containers, brought off site and delivered to a suitable independent commercial facility for treatment / re-use / disposal in accordance with applicable legislation Decommissioning Options & Removal of Development The available options at the projected end of the wind farm s operational life are as follows: Refit the turbines key components and continue electricity production. Repower with the most up-to-date technology and continue electricity production. Decommission the development and reinstate the site. It is not envisaged at this stage that special environmental considerations will apply during the ultimate decommissioning of the wind farm. The same principles of mitigation works as apply to the construction works will apply to decommissioning. Decommissioning will comprise the following: All turbines will be dismantled by crane, and this will entail removing the turbine blades and the nacelle containing the gearbox and generator, followed by removal of the tower sections. Control equipment and switchgear will be removed from the Electrical substation and the Control Building will be demolished. The upper sections of the turbine foundations will be removed to below ground level. The remaining lower parts will be covered and the ground will be left to re-vegetate naturally. Underground cables will be cut back and left buried in order to avoid disturbance of the already vegetated areas. Tracks that are not required on an ongoing basis by the landowners will be covered over and the ground will be left to re-vegetate naturally. Foundations will be covered over and marked All demolition waste will be removed from the site. The Visitor Centre will either be decommissioned or remain in situ. Once the wind farm is decommissioned one of the key elements of the centre will be lost however, it could continue to provide a focal point for the local community or be redeveloped for an alternate purpose. Project Description 2.30

34 Costs of Decommissioning The decommissioned electrical equipment, which will comprise control and switchgear equipment, and turbine transformers and substation transformers, will have a residual value of at least the cost of its removal. This together with the scrap value of wind turbine components, mainly comprising recyclable steel, will provide a fund that will more than meet the financial costs of decommissioning and site reinstatement. The DoEHLG Wind Farm Planning Guidelines (Section 7.19) recognise that the use of long-term bonds puts an unreasonable burden on developers given the long time span involved in wind energy developments and is difficult to enforce. It notes as follows: The recycling value of the turbine components, particularly copper and steel, should more than adequately cover the financial costs of the decommissioning. Accordingly, the use of a long-term bond is not recommended MITIGATION OF POTENTIAL IMPACTS The EPA s Advice Notes on Current Practice (in the preparation of EISs) accompanies the Guidelines on the information to be contained in EISs, also published by the EPA. The Advice Notes are divided into five sections, each providing detailed guidance on specific aspects to be considered in the preparation of an EIS. Section 3 provides guidance on the topics which would usually be addressed when preparing an EIS for a particular class of development, highlighting typical issues which arise. The projects are grouped into 33 generic types, which have similar development or operational characteristics. Project Type 33 addresses installations for the harnessing of wind power for energy production and the Possible Mitigation Options that are identified are as follows: Site selection to avoid intrinsic sensitivity is the principal mitigation option for this project type. Site layout to achieve appropriate orientation and alignment is an appropriate secondary measure. Utilisation of non-disruptive construction methods for access roads, buried cables and other site works can significantly ameliorate impacts on water, soil, ecology and archaeology. A full discussion on alternative design layouts is provided in Chapter 4 and demonstrates that the Oweninny Wind Farm designed is consistent with the strategy outlined. The design has also been influenced by extensive consultation with stakeholders resulting in the following actions incorporated into the design to minimise potential impacts: Piling of turbine foundations in sensitive locations rather than excavation, such as in the vicinity of the Bellacorick Iron Flush and Lough Dahybaun to minimise potential impact on groundwater level as discussed with National Parks and Wildlife Service. Avoidance of the Hen Harrier winter roost location as discussed with NPWS Relocation of turbine foundations away from bog remnants as advised by the Irish Project Description 2.31

35 Peatland Conservation council. Provision of signal transmission corridors to ensure no interference with current transmission signals across the site. Maintaining specific set back distances from dwellings (at least 1,000m), site boundaries, rivers and streams and designated areas. Minimising import of construction material through development of an on site borrow pit with consequential reduction in traffic and transport on the N59 Minimising the potential for cumulative impact through early engagement with other wind farm developers (Cluddaun and Corvoderry). This has resulted in access provision to the Coillte proposed Cluddaun wind farm through the Oweninny site thereby reducing the potential impact on local roads that could otherwise arise from the Cluddaun development for example OTHER DEVELOPMENTS There are proposed and permitted wind farm developments in the general region and those within 20 km of Oweninny, as shown in Figure 2-13 are as follows: Coillte proposed wind farm development at Cluddaun Co. Mayo currently at pre application consultation (PL16.PC0133). This site is located on Coillte lands on the northern boundary of the Oweninny site. It will comprise a development of 48 wind turbines with a rated output up to 150 MW. Access to this wind farm development will be provided through the Oweninny site off the N59 via the access track network. Corvoderry Wind Development comprising ten wind turbines with 100m overall height (Planning reference 11838). This wind farm is located within the Oweninny site and the developer has a right of way along the existing Bellacorick wind farm access road. Planning permission 09/259 for a wind farm development at Dooleeg, Bellacorick (one 2 MW wind turbine) granted on appeal to ABP (PL ). Planning permission 09/286 for a conventional 200 MW gas fired peaking plant was granted to Constant Energy along the Srahnakilla road GRID CONNECTION EirGrid has confirmed that Phase 1 and Phase 2 of the proposed development will connect to the existing Bellacorick 110 kv substation and the internal overhead line routes and cables to connect these two phases have been designed and are included in the planning application for the wind farm With regard to Phase 3 of the Oweninny wind farm development it will be a matter for the transmission system operator EirGrid as to where the connection for this phase to the Electricity Network will take place. This is not in the control of the developer. The actual route and connection infrastructure to be used will be a matter to be addressed when the location and method of connection to the Electricity Network is fully and finally established. As noted in the DoEHLG Wind Farm Planning Guidelines (Section 7.12), it will be necessary to submit a separate planning application for the works to connect the Project Description 2.32

36 development of Phase 3 to the Electricity Network, other than where the connection to the grid constitutes exempted development. Condition 4 in the current planning permission (PL ) requires that work on the wind farm should not proceed until written consent on the adequacy of the electricity transmission system to accommodate the additional output of that phase upon completion of its commissioning has been received from the grid operator. Connection to the national electricity transmission grid is not a matter for the developers of Oweninny Wind Farm in terms of its method (voltage level, overhead line or underground cable), location (new or existing substation) or the lands that may be affected (in the ownership of the developers or others). In recognition of the developer having no role in such matters, the DoEHLG Wind Farm Planning Guidelines advise as follows: It is not appropriate to attach conditions in regard to grid connections on land outside the ownership of the applicant as part of the permission for the wind energy development. Project Description 2.33

37 Figure 2-1: Site Layout Project Description 2.34

38 Blade Nacelle Tower Figure 2-2: Typical turbine components (ESB Curryfree wind farm) Project Description 2.35

39 Meteorological instruments Main Shaft Gear Box Main Bearing Generator Yaw Motor Figure 2-3: Typical Wind Turbine Nacelle (Courtesy of Nordex) Project Description 2.36