Strathy Wood Wind Farm Peat Volume Calculations

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1 22 nd July 2015 Nikki Anderson Energy Consents & Deployment Unit Scottish Government 4th Floor, 5 Atlantic Quay 150 Broomielaw Glasgow G2 8LU Dear Nikki Strathy Wood Wind Farm Volume Calculations I am writing with regards to the Further Environmental Information (FEI) document submitted to ECDU in relation to the planning application for the Strathy Wood Wind Farm. Management Plan Our team has noted that within Table 2 of Appendix 11-4 Draft Management Plan of the Strathy Wood Wind Farm FEI document submitted to ECDU in May 2015 there are some minor errors in the values provided for the excavated and reinstated volumes of peat. The following information should be read in conjunction with the Management Plan, which is an iterative document and will be revised during pre-construction phases to accommodate changes to design. The corrected figures are detailed in the table below which should replace Table 2 of Appendix Revised Table 2 of Appendix Excavated and Re-instated Volume Estimates (cubic metres) Provenance Borrow pits GIS measured Hardstandings & ancillary pad Carpark & Control Building Substation compound GIS measured (minus s where access track overlaps) GIS measured GIS measured Site compound GIS measured Average Depth Excavated (m 3 ) Location Volume (m 3 ) volume provenance Borrow pits Borrow pit restoration Verges for hardstandings & ancillary pad Car park and control building verges Substation compound 3420 Assume 2m 3 verges for approximately 95m edge of each hardstanding 318 Infill on temporary (car park only) and 65m usable verge 300 Assume 2m 3 verge around 300m perimeter Site compound 9694 Infill on temporary Atmos Consulting Limited is a Limited Company Registered in Scotland Number SC Registered Office: Rosebery House, 9 Haymarket Terrace, Edinburgh, EH12 5EZ

2 Provenance Laydown GIS measured Batching plant GIS measured Turning GIS measured New Access Cut Track 6121m Upgraded Access Track 6000m Total of cut track x 6m 1.2 Total of new track x 2m track 'extension' Turbine Bases GIS measured Infrastructure Buffer (1m) GIS measured data Average Depth Excavated (m 3 ) Location Volume (m 3 ) volume provenance Laydown 2253 Infill on temporary Batching plant 1071 Infill on temporary Verges for turning heads (2m 3 x 7 x 85m) and borrow pit Verges for total site new access tracks (2m 3 x 7400m) and borrow pit 1190 Assume 2m 3 verges for 85m of usable verge for each turning head Assume 2m 3 verges per m of all new access tracks (including floating) Verges Assume 2m 3 verges per m of upgraded access tracks Turbine bases, verges and borrow pit Drainage buffer Borrow pits Total 95,105 95, Assume 225m 3 per turbine base Infill on drainage Borrow pit restoration The total volume of excavated peat is estimated to be 95,105m 3, rather than the 87,809m 3 previously stated. This change should also be considered to apply to the statement on Page 45 of the main text of the FEI under the section headed Effects on. Furthermore it is noted that on Page 45 of the FEI, it is stated that the estimated volume of excavated peat has reduced, following the design changes. In this statement the revised value is compared against the value presented in the ES submitted in 2013, calculated for the original larger 26 turbine layout of the Strathy Wood Wind Farm. Page 45 of the FEI states that the excavated peat associated with the original 26 turbine scheme is estimated to be 86,075 m 3 which was based on methodology and site data available at the time of the 2013 ES. Further peat survey data has since been captured and current methodology has been adopted in the FEI, therefore the two values do not actually present a like for like comparison. In the interest of clarity, the excavated peat volume associated with the 26 turbine layout has been recalculated using the current data and methodology and the results of this analysis are presented in the following table. 1 This buffer was applied during layout design to provide protection to water bodies and does not necessarily represent proposed excavation; the peat implications of drainage would vary across the site. The depth of excavation for drainage would range from 0.5m to 1m, and therefore peat depth excavation has been capped at 1m where peat depth exceeds this depth. These capped values have been used when calculating the average peat depth within the buffer. It has been assumed that excavation to 1m is required in this buffer as a worst case scenario. In order to avoid buffer overlap, all site was treated as one entity with the 1m buffer applied to the entity.

3 Strathy Wood Wind Farm, original 26 Turbine layout - revised volumes of excavated peat. Provenance Average Depth Excavated (m 3 ) Borrow pit GIS measured Crane hardstanding GIS measured Car park & Control Building GIS measured Site compound GIS measured Laydown GIS measured Batching plant GIS measured Turning GIS measured New Access Track 7300m Total of cut track x 6m Upgraded Access Track 7900m Total of new track x 2m track 'extension' Turbine Bases GIS measured Infrastructure Buffer (1m) GIS measured Total 111,852 This table has been updated to also include the 1m buffer to allow for drainage based on the original 26 turbine layout. Therefore it can be seen that following the revision of the Strathy Wood Wind Farm as presented in the FEI, the estimated volume of excavated peat has reduced by approximately 15% from 111,852m 3 to 95,105m 3 for the footprint based on a worst case scenario which also takes a 1m buffer into account. As stated in the FEI, it is anticipated that all peat would be reused on site with no waste peat generated. Carbon Balance Calculator The data and calculations of carbon balance in the FEI did not include the 1m buffer to allow for drainage - this buffer was applied during layout design to provide protection to water bodies and does not necessarily represent proposed excavation. In line with the peat management plan changes above, the carbon balance calculator has also been revised to include the drainage buffer as a worst case scenario. Tables A14-2, A14-4 and A14-5 in Appendix 14-1 have been updated and should be replaced with the revised tables presented below. In the main report Table A14-2 should also be replaced as detailed below.

4 Revised Table 2 of Appendix 14-1 Summary of Core Input Data Used in the Carbon Payback Calculator Infrastructure Specified Inputs Number Total (m2) Depth depth depth notes Borrow pit points within Crane hardstanding irregular shape T8, 13, 19 and 24 no peat depth on. Nearest point taken. Respectively: 35, 68, 37 and 25m away Turbine foundation octagonal T 8, 13, 19 and 24 no peat depth taken on. Nearest Point taken. Respectively: 15, 81, 51m and 8m away New access track floating This has not been included in peat excavation calcs New access track not floating Existing access track not floating Additional Inputs points within 20m of centreline This has been included in carbon balance spreadsheet, however the carbon balance calculator does not make provision for inclusion of peat depth in relation to the track upgrades. There will be upgrades to the existing tracks as they will require widening. Laydown irregular shape points within Batching plant irregular shape points within Substation compound Nearest point 10m away Site compound points within Carpark Nearest point 10m away Control building Same point as carpark, 27m away Turning 7 irregular shape turning s with no peat depth taken on. Nearest point taken. Drainage Buffer

5 Revised Table 4 of Appendix 14-1 & Table 2 of FEI Chapter 14 Net carbon dioxide emissions and carbon payback period of the revised Development Net emissions of carbon dioxide tonnes of CO2 equivalent (t CO2 eq.) Exp ,418 52, ,662 coal-fired electricity generation (years) grid-mix of electricity generation (years) fossil fuel - mix of electricity generation (years) Revised Table 5 of Appendix 14-1 Carbon payback period (months) with and without restoration With restoration Total tco 2 loss from peat (removed + drained) 65,855 Number of Months 17 Without restoration Total tco 2 loss from peat (removed + drained) 106,489 Number of Months 20 Overall the predicted carbon loss for peat due to wind farm construction, operation, decommissioning and restoration, including the 1m drainage buffer is 65,855 tco2 with restoration and 106,489 tco2 without restoration. Post restoration carbon fixation is simulated for a maximum of 15 years after decommissioning of the wind farm. Overall the carbon payback period with restoration is 17 months and without restoration is 20 months taking the 1m buffer included in the updated assessments into account. This assumes the wind farm replaces energy generated from a mix of fossil fuels I trust the above clarification is of assistance; we would be pleased to discuss the matter further with you or answer any questions that may arise. Thank you for your consideration of this matter. Yours sincerely Sarah McMonagle Senior Consultant Atmos Consulting Ltd. on behalf of E.ON Climate & Renewables UK Developments Limited Enc: CD containing carbon balance calculation spreadsheets