Landfills: An Overview

1. Landfills: An Overview TREN 3P14: Sustainable Integrated Waste Management David T. Brown Dept. of Tourism and Environment Brock University St. Catharines, Ontario L2S 3A1 References: O’Leary, Philip & Patrick Walsh. Landfill Course. Waste Age, January 2002 – January 2003.

2. Landfill • conceived in the 1960s as a planned method of solid waste disposal • prior to that, municipal solid waste disposed of in organized or unorganized open dumps. • waste may not have been covered • likely was burned as part of the disposal • practice

3. Landfill 1970s – North America and Europe: • initiatives made to improve solid waste disposal practices

4. Sanitary Landfill • an engineered facility for the disposal of municipal solid waste (MSW) designed and operated to minimize public health and environmental impacts

5. Photo:www.gin.hr/ project_jak.htm

6. Sanitary Landfill • typical landfill consists of several cells in which the waste is systematically placed • Landfill base usually consists of a liner (clay or synthetic) that minimizes the leakage of liquid waste materials and leachate into groundwater system

7. Installation of synthetic landfill liner Photo:www.gin.hr/ project_jak.htm

8. First cell of landfill(area method) Access ramp Refuse Photo: David T. Brown

9. Sanitary Landfill • Waste built up in layers and compacted • Wastes covered daily with soil, geomembranes, or other cover materials to prevent lightweight wastes, dust, and odors from escaping and to discourage vermin

10. Photo: Bung-orn Thirapoj

11. Weigh Station Photo: David T. Brown

12. Weigh Scale operator Photo: David T. Brown

13. Truck on weigh scale at entry Load cell to weigh truck Photo: David T. Brown

14. Photo: David T. Brown

15. Landfill liner detail Synthetic liner Photo: David T. Brown

16. Sanitary Landfill • Modern landfills are sophisticated facilities that require millions of dollars to build • Services provided often valued at millions of dollars per year

17. Sanitary Landfill • Typical landfill operates between 10 and 20 years • During this period, waste in the landfill undergoes complicated decomposition processes

18. Sanitary Landfill • Decomposition results in the release of: • liquids (leachate)must be contained in the landfill and treated prior to release • gases must be managed as they escape through the landfill cover, or are collected for burning or storage

19. Lined landfill section Liner Ponded water Sand cover to protect and retain plastic liner Photo: David T. Brown

20. Leachate retention pond Culvert Photo: David T. Brown

21. Access well in new section Liner Access well Photo: David T. Brown

22. Sanitary Landfill Various options available to landfill operators regarding: • Preparation of waste before it arrives at the landfill • Compaction procedures for waste • Alternatives for managing leachate and gas

23. Technological innovations Recent technological innovations include: • improved groundwater monitoring and leachate collection systems • Improved gas monitoring and collection systems • meet air pollution control standards • facilitate energy recovery • installation of geosynthetic covers • introduction of large waste compaction equipment • Development of alternative cover materials installed during final closure

24. Leachate collection conduits Photo:www.gin.hr/ project_jak.htm

25. Bioreactor landfills • Landfill is operated as a managed treatment facility • Natural decomposition process accelerated to • reduce waste volume • increase the amountof waste that can be landfilled • Bioreactors expected to reduce long-term emissions into the groundwater or the atmosphere. • Several bioreactor landfills being operated on a limited basis in the United States and in Western Europe.

26. The Life of a Landfill Phase 1: Site Selection and Investigation • sites evaluated from geotechnical and environmental standpoints • initiation of a public participation program, to openly communicate with the public and minimize potential landfill opposition

27. The Life of a Landfill Phase 2: Design and Regulatory Approval • detailed plans and specifications for facility are prepared • regulatory approvals are obtained • financial commitments are received • construction is initiated

28. The Life of a Landfill Phase 3: Site Construction • development of support facilities • development of the landfill’s first one or two cells Phase 4: Operation • landfill opened and operated over a period of years • additional cells constructed as needed

29. The Life of a Landfill Phase 5: Site Closure • When cells are filled to capacity they are closed and monitored • Final closure often involves site remediation Phase 6: Long-Term Care • Monitoring for 30 years after closure • Owner / operator responsible for remedial action and facility maintenance

30. Environmental Considerations Groundwater Quality • If landfill not properly lined, waste can escape into groundwater • Most landfills constructed with a combination of low-permeability compacted soil and geomembranes

31. Ref: O’Leary, Philip & Patrick Walsh. 2002. Land Disposal of MSW: Protecting Health & Environment. Waste Age- February 2002, pp. 38-43.

32. Photo: David T. Brown

33. Environmental Considerations Wetland and Stream Protection • Surface runoff detrimental to adjacent wetlands and streams • Chemical, organic, and sediment contamination are all problematic • May be reduced or eliminated with proper design and management

34. Photo: David T. Brown

35. Photo: David T. Brown

36. Photo: David T. Brown

37. Environmental Considerations Air Quality • Odours • Gaseous emissions: • direct from the waste (volatile solvents, fumes, odours) • from anaerobic decomposition (e.g., methane)

38. Environmental Considerations Air Quality • Blowing grit, dust, lightweight litter • Combustion gases, smoke, and particulates, if landfill catches fire

39. Photo: David T. Brown

40. Environmental Considerations Greenhouse Gases • Landfills emit significant quantities of methane and carbon dioxide • Control mechanisms are being mandated at the provincial level (Canada) and national levels (USA)

41. Landfill gas combustion stack Landfill gasliquification facility Photo: David T. Brown

42. Safety Considerations Explosion Potential • Landfill gas is a potentially explosive combination of methane and carbon dioxide • Explosive landfill gas may migrate underground into buildings, or collect in explosive pockets onsite

43. Safety Considerations Slope Stability • landfills have become larger; heights have significantly increased => leads to slope stability concerns • Steep slopes canfail, with catastrophic results. Photo: Bung-orn Thirapoj

44. Photo:www.gin.hr/ project_jak.htm

45. Photo:www.gin.hr/ project_jak.htm

46. Safety Considerations Slope Stability • earthquake activity can also potentially cause slope failure at a large landfill • also an issue at landfills that receive specialized wastee.g. if wastes contain significant amounts of water, slope stability decreases

47. Safety Considerations Worker Safety Materials in landfills may be hazardous. Workers need protection from: • Sharp, hazardous, infectious or pathogenic wastes • Dust and particulates • Noise and hazards from vehicles and equipment • Fire and explosion • Vermin • Volatile substances, odours • Extreme weather, wind, high and low temperatures • Construction accidents

48. Photo: Bung-orn Thirapoj

49. Decomposition in landfills • The decomposition process is a principal driving force in the development, operation and closure of a landfill • MSW contains organic material that naturally decomposes when landfilled

50. Decomposition in landfills Two phases: • Aerobic(oxygen present) • Anaerobic (stages 1 and 2) (little or no oxygen present)