Rehabilitation of a mine site

1. Tel: (07) 3316 2531 Fax: (07)3295 9570 www.oresomeresources.com Rehabilitation of a mine site

2. Rehabilitation of the Ensham open-cut coal mine near Emerald in Central Queensland. Image courtesy of Ensham Resources

3. Before mining Image courtesy of Ensham Resources

4. After mining Image courtesy of Ensham Resources

5. After rehabilitation The purpose of rehabilitation is to return the site to an agreed land use. This is a legal requirement of the EPA (Environmental Protection Authority). Image courtesy of Ensham Resources

6. Open cut coal mining ‘Spoil’ is the overburden removed to reveal the coal seam. Previous spoil is piled behind the pit. In this way, the pit advances, progressively filled with new spoil. Rehabilitation will ultimately occur over the previous spoil behind the mine. Direction of advance of the pit Image courtesy of Ensham Resources

7. The Ensham Mine The pit at the Ensham mine is progressing to the right in the picture. Removal of surface overburden is in progress on the highwall side (right) and is dumped on the spoil pile (left) to fill the pit. Image courtesy of Ensham Resources

8. Rehabilitation planning An aerial view of the mine shows the plan for rehabilitation, with the areas to be rehabilitated in green. Image courtesy of Ensham Resources

9. An Environmental Impact Study (EIS) is conducted to assess the flora and fauna that exists prior to mining. An Environmental Authority (EA) is then issued with the mining lease to regulate how the mining company is to interact with the environment. The rehabilitation requirements are different for every mine. The mine proposes a rehabilitation plan and the government then adds its own conditions prior to approval. Image courtesy of Ensham Resources

10. This map highlights areas of “Endangered”, “Of concern” and “Not of concern” ecosystems within and surrounding the mine site. Image courtesy of Ensham Resources

11. This map depicts broad types of vegetation within and surrounding the mine site. The EA spells out the rehabilitation requirements that must be achieved in ground coverage and species diversity. Image courtesy of Ensham Resources

12. Before mining Image courtesy of Ensham Resources

13. After mining Image courtesy of Ensham Resources

14. Rehabilitation Image courtesy of Ensham Resources

15. Restored land Image courtesy of Ensham Resources

16. Stockpiling of topsoil pre-mining Before mining begins, topsoil is stockpiled on the highwall side. It is kept for a period until the mine has progressed and the slope of the spoil is ready for the topsoil to be replaced. Most mines salvage 200mm of topsoil but at the Ensham mine 300mm is kept. Image courtesy of Ensham Resources

17. Dumping of spoil After surface overburden has been removed by trucks, the highwall is detonated to transfer as much burden as possible to the other side of the pit. Draglines pile this overburden into high spoil piles. Image courtesy of Ensham Resources

18. Steep slopes are unsuitable for rehabilitation The volume of rock swells by 25 percent after it is detonated. Even after the coal seam is removed, the spoil piles created by draglines create hills with steep slopes formed as the spoil is dumped. In years past, these slopes were rehabilitated. However, the slope was found to be too steep to be stable. This picture shows how unstable such a hill is with regard to erosion and landslides. Image courtesy of Ensham Resources

19. Reshaping of the slope Bulldozers and trucks are used to reshape steep spoil piles into gradual slopes that are suitable for rehabilitation. Generally, the maximum gradient of slope accepted by the Environmental Authority is one in ten (ten percent), although sometimes one in fifteen is accepted. Image courtesy of Ensham Resources

20. A site levelled prior to rehabilitation, awaiting another truck and shovel dump of spoil. Image courtesy of Ensham Resources

21. Image courtesy of Ensham Resources

22. Once the required gradient is obtained, bulldozers are used to smooth the surface. Working the material in this manner has the added advantage of making it finer on the surface and more conducive to plant growth. Image courtesy of Ensham Resources

23. Prior to rehabilitation, the surface resembles a big, flat moonscape. It takes some four or five years from commencement of mining to reach this stage. It’s not possible to rehabilitate right up to the mining point and a further delay results because the ground must be left to settle for twelve months. 1 10 A slope of 1 in 10 Image courtesy of Ensham Resources

24. Swelling of the rock means that it's not possible to return the land to its original contours. A gently sloping hill with a flat top is constructed behind the mine. Image courtesy of Ensham Resources

25. Laying of topsoil Topsoil stockpiled prior to commencement of mining is trucked to the rehabilitation site. Image courtesy of Ensham Resources

26. Image courtesy of Ensham Resources

27. Image courtesy of Ensham Resources

28. Image courtesy of Ensham Resources

29. Topsoil is dumped, ready to be spread by bulldozers or graders. Image courtesy of Ensham Resources

30. Image courtesy of Ensham Resources

31. Spreading of topsoil Image courtesy of Ensham Resources

32. Image courtesy of Ensham Resources

33. Topsoil is generally spread to a depth of 200mm. At the Ensham mine, 300mm. Image courtesy of Ensham Resources

34. The importance of topsoil (left) is most apparent adjacent to a site where topsoil is yet to be laid (right). Image courtesy of Ensham Resources

35. Laying of manure Manure is laid over the topsoil to further encourage plant growth.. Image courtesy of Ensham Resources

36. Manure is spread using a belt-driven bin behind a tractor. At the Ensham mine, 15 tonnes of manure is spread per hectare. Image courtesy of Ensham Resources

37. Pegging the contours Surveyors and environmental engineers peg lines of equal height to mark the contours on the rehabilitation site. Image courtesy of Ensham Resources

38. Deep ripping along the contours A bulldozer follows the pegs to deep rip along the contours to a depth of about one metre. This increases infiltration of water and provides a rough surface to reduce runoff and erosion. Once grass has established itself on this surface, the contours will completely eliminate any rainwater runoff. Image courtesy of Ensham Resources

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40. Image courtesy of Ensham Resources

41. Controlling drainage Drainage is further controlled by means of 20-30m wide horizontal benches between every 100m of sloped rehabilitation land. This reduces the likelihood of rainwater running off in torrents. Small rock walls called ‘rills’ are constructed around the rehabilitation area to stop runoff from the mine washing away the topsoil or killing the grass. Image courtesy of Ensham Resources

42. Different grasses and legumes are seeded on rehabilitation sites according to the final land use of the site. At the Ensham mine, grasses that are ideal for cow fodder, such as Buffel grass and Rhodes grass, are used commonly, in addition to six other species according to the soil type. While some mines use both native and introduced species, Ensham has found that the introduced species quickly take over, so native species are no longer seeded. Image courtesy of Ensham Resources

43. Scattering of seed Grass is seeded at the rate of 25kg of seed per hectare by a contract farmer. The seed is spread by a fertiliser spreader on the back of a farm tractor. Summer grasses require a certain soil temperature to strike and grow, so in winter, 20kg per hectare of wheat seed is added to the mix. Wheat provides cover in the winter, ready for grasses to come through in summer. The aim is to get as much ground cover as quickly as possible so as to reduce erosion. Image courtesy of Ensham Resources

44. Spreading of fertiliser Fertiliser is spread at the rate of 100kg per hectare. Image courtesy of Ensham Resources

45. Wheat stubble (hay) is spread as mulch to give the land stability and water-holding capacity before the grass is established. 20 six-foot round bales of wheat hay are spread per hectare. Spreading of mulch Image courtesy of Ensham Resources

46. Image courtesy of Ensham Resources

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48. Early growth Image courtesy of Ensham Resources

49. Grass is seeded within a week of the site having been ripped. Assuming good rainfall there will be cover within a month. Image courtesy of Ensham Resources

50. Mature grass, going to seed within six months of planting Image courtesy of Ensham Resources