Linfairn Wind Farm Addendum Chapter A3: Project Description

Transcription

1 A3. PROJECT DESCRIPTION 3.1 Introduction This chapter provides a description of the changes to the Project since the ES was published. An outline Construction Environmental Management Plan (CEMP) is included within Appendix A3 of this Addendum. This will be updated and finalised prior to construction should the application be granted consent (see Section for further information). Post-consent works and construction will be carried out in accordance with the published guidance, Good Practise during Windfarm Construction 2 nd Edition Project Components The Project will comprise the elements set out within Chapter 3, Section 3.2 of the ES with the following amendments: 17 WTGs (reduced from 25). One temporary construction compound to be removed following construction of the Project. Re-location of the sub-station (control) building closer to remaining WTGs. Reduction in length of access track. Reduction in the area of forest felling. The revised layout of the Project is shown within Figure A Wind Turbine Generators It is proposed that the 17 WTGs on the site will now have a rated capacity of up to 3.2MW (increased from 2.3MW as is stated in ES Chapter 3), giving a total generating capacity of approximately 54.4MW. The revised layout has been developed to address environmental concerns while maximising the energy output of the Project. The proposed 3.2MW WTG dimensions differ to that previously stated in the ES however the maximum 126.5m to tip height remains valid. Each WTG will have a maximum hub height of up to 76m (previously 80m), a maximum rotor diameter of 101m (previously 93m) and a maximum tip height up to 126.5m. Figure A3.1 illustrates the proposed WTG dimensions. A further description of the WTGs can be found within Section of ES Chapter 3. 1 Scottish Renewables, SNH, SEPA, Forestry Commission Scotland & Historic Scotland (2013). Good Practise during Windfarm Construction 2 nd Edition. 14/7048/001/GLA/O/R/001 Revision B1 Page 1 of 7

2 Table A3-1 sets out the revised WTG locations. Please note that the WTG numbers remain as previously stated in the 2013 ES for ease of reference. Table A3-1: WTG Locations WTG No. Easting Northing /7048/001/GLA/O/R/001 Revision B1 Page 2 of 7

3 3.2.2 Access Tracks on Site The revised Project will include approximately 13km of access tracks for construction and maintenance purposes. The access tracks which link WTGs 1 to 6 have been removed from the revised layout as has the track to WTGs 11 and 12. Section of ES Chapter 3 describes the access tracks proposed whilst Figure 3.3 of the ES highlights track construction details and Figure 3.4 the site entrance details. Floating tracks will be used where peat depths are greater than 1m. For the Project, this equates to approximately 585m in length of floating track (around 5% of the total length of access tracks). There will be no excavation into bedrock for a length of at least 100m of access track in proximity to private water supply 1 to the north of the site (see Figure A9.2). A level surface and foundation for the access track will be constructed at this location by building-up on the downslope side of the track location rather than through excavation of a cutting into the hill slope (see Appendix A9.1) Watercrossings It has been identified that 16 watercrossings would be required (see Figure A9.1 for the location of the watercourse crossings). The construction of watercourse crossings will be carried out in accordance with SEPA guidance and the appropriate level of authorisation under The Water Environment (Controlled Activities) (Scotland) Regulations 2011 (as amended 2013) will be obtained prior to work commencing. The design, sizing and construction of the required watercrossings will be carried out with reference to guidance within the CIRIA Culvert Design and Operation Guide (C689). Bottomless structures will be used to maintain existing bed substrate and a clear span bridge structure will be used for the crossing of Palmullan Burn. Chapter A9 of this Addendum submission, ES Chapter 9 and Appendix A3 (CEMP) provide further details in relation to the required watercrossings to accommodate the access tracks Construction Compound Due to the removal of WTGs in the north of the site, the northernmost temporary construction compound will be removed leaving the southern compound to be utilised during construction of the Project. A full description of the proposed compound can be found within Chapter 3, Section of the ES. 14/7048/001/GLA/O/R/001 Revision B1 Page 3 of 7

4 3.2.4 Sub-Station (Control) Building The sub-station building will be relocated to a location close to the remaining temporary construction compound. Being in closer proximity to the WTGs, this will reduce the need for unnecessary cabling and associated excavation. ES Chapter 3, Section sets out the sub-station details. Figures 3.7 and 3.8 of the ES illustrate the indicative plan and elevation of the building. The specific specifications in the drawings will be subject to change dependent on the final contractor requirements Grid Connection The grid connection is subject to a separate Section 37 (Electricity Act 1989) application. The grid application was submitted in September Underground Cabling As specified in the ES, all power cabling on site from and between the WTGs to the sub-station (control) building will be buried in trenches approximately 1.5m wide by 1m deep located adjacent to the internal access tracks. The cabling between the WTGs and the sub-station building will be required to cross seven watercourse crossings (see Figure A9.1 for the location of watercourse crossings). At these crossings, options will include open cut or horizontal directional drilling (dependant on the ground conditions). Isolated open cut methods would be utilised on smaller streams. Using this method, a whole section of the channel is isolated using barriers that span the full width of the watercourse. This keeps the crossing point dry and the water is transferred downstream of the works area. For any culverts, the cable route can be pulled away from the access track and through the culvert Felling Requirements Due to the removal of WTGs 1 to 6 in the northern section of the site, the quantity of trees to be felled has reduced by over 30%. The access track from the site entrance to WTG 7 will pass through areas of commercial forestry. Using GIS mapping, including a 50m buffer to accommodate for the track, it has been determined that approximately 15 hectares (ha) of forest will be removed to accommodate the track. The felling required for the purpose of carrying out development authorised by planning permission is exempt from a felling licence under Section 9, Paragraph 4(d) of the 1967 Forestry Act. If permission was granted for the Project, a separate felling licence would therefore not be required for the felling necessary for the access tracks. Further felling to the south of the site may be required due to the proximity of the WTGs to the forest boundary. This would however be dependent on the chosen WTG supplier s specific requirements post-consent. Any felling required would be subject to a separate felling licence. 14/7048/001/GLA/O/R/001 Revision B1 Page 4 of 7

5 The felling requirements have been considered in all specialist assessments as appropriate (see Chapters A6 to A15 for further information) Tree species The Dyke forest design plan was provided by Forestry Commission Scotland (FCS). The plan shows that the majority of forestry lost as a result of the access track consists of a sitka mix, followed by a section of sitka / larch mix and a section of birch mix. A small area of larch mix and upland broadleaf woodland will be lost towards the western boundary of the Dyke landholding Timescales for removal It is proposed that felling on the Project site will take place in conjunction with the construction of the first section of internal track to gain access to the trees. Therefore felling has been tentatively scheduled into months one and two of the construction programme as illustrated in addendum Chapter A14 (Traffic and Transportation) Restocking of felled area The felled area will remain clear throughout the lifetime of the Project to accommodate continued access to the WTGs. Following decommissioning of the Project, the area will be restocked with an appropriate species mix, proposed to be broadleaved species. This will be subject to consultation with FCS Compensatory planting Compensatory planting will be carried out to mitigate for removal of forestry and a replanting plan will be drawn up prior to construction. This will be subject to a separate Section 75 agreement. It is proposed that the replanting will occur in the Knockgardner landholding to the north of the site (see Figure 2 of Appendix A7.4 (Outline Habitat Management Plan (HMP)) at present however options are also available for compensatory planting elsewhere off site if required. The specific forestry planting areas will be determined following an assessment of ground conditions and will avoid all areas where peat depths are over 0.5m. It is proposed that upland mixed broadleaf species will be planted to compensate for the forestry loss (see Appendix A7.4 (Outline HMP) for further details). The Outline HMP identifies a possible 44.18ha which would be suitable for broadleaf replanting. This would be further refined post-consent. Planting will take place within the first available planting season following construction of the Project. 14/7048/001/GLA/O/R/001 Revision B1 Page 5 of 7

6 3.2.8 Site Management Management on site will be carried out in accordance with the CEMP (a draft of which is included as Appendix A3 of this Addendum). The principal contractor will be responsible for expanding and tailoring the CEMP in accordance with related planning conditions, current best practice and their own specific working methodologies and practices. The CEMP will remain a live document throughout the construction process as further site investigations and surveys are undertaken and detailed methodologies become available Decommissioning, Restoration and Aftercare of the Site Following the anticipated 25 year lifespan of the Project (application is for 25 years), a decision will be made as to whether the site is repowered (replacement of WTGs with newer models) or the WTGs removed. The site would be subject to a further application should repowering be the chosen option. The following sections describe the decommissioning, restoration and aftercare methodology for the site. It should be assumed that following decommissioning, the site will be returned to at least its original condition as soon as possible or as appropriate following removal of infrastructure from the site. Decommissioning works will be required to adhere to similar methodologies and guidelines as stated within the outline CEMP (and subsequent versions) (see Appendix A3). In addition, requirements at the time of decommissioning must be assessed as historically planned procedures may differ from that required at the point of delivery. A decommissioning plan will be submitted and agreed with South Ayrshire Council prior to decommissioning commencing. This plan will reflect current best practice. Appropriate mitigation, environmental management and monitoring measures will be adopted, as during the construction phase, subject to advances in approaches and changes in legislation at the time of decommissioning. Execution of decommissioning would be as follows: De-energising the site high voltage disconnection or isolation for partial decommissioning, followed by low voltage disconnection of affected WTGs. Handover of site responsibility to the principal contractor and management of operator access and site set up. Decommissioning of structures generally a reverse of the installation procedure (see following sections for further information). 14/7048/001/GLA/O/R/001 Revision B1 Page 6 of 7

7 Decommissioning of Structures The WTG internals will be stripped out and the transformers removed. This includes: Controlled dismantling of WTGs (blades, nacelle and tower). Removal of cables (whole or partial) and making good trenches (throughout). Removal of crane pads and backfilling / landscaping. Removal of sub-station and control building. Removal of access tracks and reinstatement of watercrossings (see section below). Final landscaping (seeding). It is likely that around 1m of the WTG foundations would be removed and the topsoil placed on top as is currently considered appropriate. There is a relatively low environmental risk with any reinforced concrete that is left in situ. The noise, ground disturbance and cost along with associated CO 2 emissions for removal of all of the foundations may create a larger environmental impact than leaving some in situ 2. It is noted however that recommended approaches may evolve during the 25 year lifespan of the Project. A further assessment of ground conditions will be carried out prior to decommissioning to determine the most appropriate approach for the site. Re-use or Recycling of Materials Where possible, materials such as the WTG components will be reused or recycled in line with the Scottish Waste Hierarchy guidance. It may be possible for WTGs to be refurbished / reconditioned and sold for use on other wind farm sites Access Tracks As with the WTG foundations, it may be appropriate for the access tracks to remain insitu. The land uses that develop during the Project s operation may render it desirable to retain the tracks to facilitate appropriate land management. Where they are not required, tracks will be restored and re-seeded using an appropriate seed mix, approved in advance by SNH Decommissioning Bond Should the Project be granted consent, a Decommissioning Bond will be finalised and agreed with South Ayrshire Council. It is anticipated that this would be a condition of consent. Typical values are in the order of 15,000 per MW installed and the dismantling of the WTGs is assumed to be paid for by monies recovered from onward sale or the scrap value of the components 2. 2 SNH (2013) SNH Commissioned Report No.591: Research and Guidance on Restoration and Decommissioning of Onshore Wind Farms. 14/7048/001/GLA/O/R/001 Revision B1 Page 7 of 7