1. 1 The Replanting of Lochaber Hydro Power Station by Andrew Thick

2. 2 Topics to be covered today Scheme modelling; Operating capability of Lochaber; Turbine selection; Penstock works.

3. 3 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

4. 4 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

5. 5 Spey Dam

6. 6 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

7. 7 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

8. 8 Laggan Dam

9. 9 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

10. 10 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

11. 11 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

12. 12 Loch Treig and Dam

13. 13 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

14. 14 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

15. 15 Schematic of the Lochaber Scheme Loch Laggan & reservoir Loch Treig Spill Gravity Inflows Power- house Tailrace Spill Surge Chamber Loch Linnhe Spey reservoir Penstocks tunnel

16. 16 Penstocks, Powerhouse and Smelter

17. 17 Simplified Lochaber Scheme Model Q Tspill Q P/H Q Tin Laggan Q Tin Q Tunnel Treig Q Lspill Q Lin Q intakes Gravity Intake Flows are combined with Reservoir Inflows

18. 18 Energy Modelling Results Trial1234567 Installed Cap. (MW)658060708090100 Overall Efficiency (%)7587 Headloss Coeff. (k)0.0210.0172 Operating ruleExt Max E Laggan Spill (mcm)2,0341,7944,1601,7091,2271,074801 Treig Spill (mcm)15412185720154107 Ave. Energy (GWh/yr)467569523574581583580

19. 19 Scheme Operating Capability Diagram 9.3 % Q 90.7 % Q Average Operation 0 % Q 100 % Q No Gravity Inflows 100 % Q 0 % Q Max. Gravity Inflows

20. 20 Operating Capability in terms of Loch Treig Level Note: 90.7% of water from Loch Treig 9.3% of water from gravity intakes

21. 21 Scheme Operating Capability Diagram 9.3 % Q 90.7 % Q Average Operation 0 % Q 100 % Q No Gravity Inflows 100 % Q 0 % Q Max. Gravity Inflows

22. 22 Operating Capability in terms of Surge Shaft Water Level Penstock Limitation Note: 90.7% of water from Loch Treig 9.3% of water from gravity intakes

23. 23 Scheme Operating Capability Diagram 9.3 % Q 90.7 % Q Average Operation 0 % Q 100 % Q No Gravity Inflows 100 % Q 0 % Q Max. Gravity Inflows

24. 24 Note: All water from Loch Treig Operating Capability in terms of Surge Shaft Water Level

25. 25 Scheme Operating Capability Diagram 9.3 % Q 90.7 % Q Average Operation 0 % Q 100 % Q No Gravity Inflows 100 % Q 0 % Q Max. Gravity Inflows

26. 26 Operating Capability in terms of Surge Shaft Water Level Note: All water from gravity intakes

27. 27 Scheme Operating Capability Diagram 9.3 % Q 90.7 % Q Average Operation 0 % Q 100 % Q No Gravity Inflows 100 % Q 0 % Q Max. Gravity Inflows

28. 28 Example Operation exceeding Penstock Pressure Rise Limit

29. 29 Turbine Selection The steps towards to turbine selection were: Analysis of historical data of scheme operation The number of generating units was selected – 5 Analysis of operating data from scheme model Performance data from tendering suppliers was fed into the scheme model

30. 30 Scheme Operation Frequency Plot

31. 31 Turbine Selection The steps towards to turbine selection were: Analysis of historical data of scheme operation The number of generating units was selected – 5 Analysis of operating data from scheme model Performance data from tendering suppliers was fed into the scheme model

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33. 33 Turbine Selection The steps towards to turbine selection were: Analysis of historical data of scheme operation The number of generating units was selected – 5 Analysis of operating data from scheme model Performance data from tendering suppliers was fed into the scheme model

34. 34

35. 35 Turbine Selection The steps towards to turbine selection were: Analysis of historical data of scheme operation The number of generating units was selected – 5 Analysis of operating data from scheme model Performance data from tendering suppliers was fed into the scheme model

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37. 37 Penstock works Key aspects of the penstock works were: Need to undertake the works minimising shutdown of generation. Existing penstock system was very complex. In order to maintain double isolation, the penstocks needed to be dewatered sequentially. The works were complex with poor access. Decision with RTA to laser scan the penstock system and create a 3-D model.

38. 38 Multiple buspipes Numerous Valves Bifurcations

39. 39 Penstock Area – difficult terrain!

40. 40 Penstock works Key aspects of the penstock works were: Need to undertake the works minimising shutdown of generation. Existing penstock system was very complex. In order to maintain double isolation for the penstocks needed to be dewatered sequentially. The works were complex with poor access. Decision with RTA to laser scan the penstock system and create a 3-D model.

41. 41 Survey Point Cloud Data

42. 42 AutoCAD 3-D Model

43. 43 Project Summary The generating plant has been replaced to give 25+ years life extension. The water to wire efficiency has been improved from 75% to 90+%. Energy production increased from 460 GWh/yr to 600+ GWh/yr. The scheme’s capability is better understood and limitations identified. The scheme was completed ahead of schedule and is operating successfully with minimal disruption to Smelter operations during construction

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45. Contact Details Andrew Thick BEng CEng MIMechE URS Infrastructure and Environment UK Limited International House, Dover Place Ashford Kent TN23 1HU United Kingdom Tel:+44 (0) 1233 658200 hydropower@urs.com Thank you for your kind attention