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Landfill Closure

Landfill Closure. SWANA November 2015. Closure Discussions. What is Final Closure? Regulations Steps to Implement Final Closure Design Considerations Cover Systems Contaminating Lifespan Financial Considerations. What Does Closure Mean?.

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Landfill Closure

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  1. Landfill Closure SWANA November 2015

  2. Closure Discussions • What is Final Closure? • Regulations • Steps to Implement Final Closure • Design Considerations • Cover Systems • Contaminating Lifespan • Financial Considerations

  3. What Does Closure Mean? • Final cover and environmental systems to be placed on and over the landfill once it stops accepting waste. • Final cover provides long-term protection against vectors, while reducing infiltration and soil erosion. • Long-term protection of ground and surface water resources.

  4. Closure Objectives • Minimize post-closure leachate generation (protect environment). • Minimize post-closure maintenance. • Allow site to return to some beneficial use as quickly as possible. • Make site aesthetically acceptable. • Accommodate settlement. • Prevent wind blown litter. • Suppress fire dangers. • Monitor performance of engineered controls.

  5. Regulations • Municipal Refuse Management Regulation (1986) • Draft Guideline for the Closure and Reclamation of Municipal Waste Disposal Grounds (1998) • Saskatchewan Environmental Code, Landfill Chapter • Stormwater Guidelines (2014)

  6. Municipal Refuse Management Regulation • Submission of proposal and approvals required to closure landfill. • Ministry of Environment sets terms and conditions to carry out landfill closure, dependant upon site sensitivity.

  7. Draft Guideline for the Closure and Reclamation of Municipal Waste Disposal Grounds • Closure / Decommissioning Plan • Assess level of risk to determine minimum closure and reclamation requirements. • Includes: • Notification – public notification of intent to close. Sign placement at entrance. • Site Clean-Up. • Day of Closure – Public access prohibited. • Rodent control. • Grading and Capping. • Site Plan. Complete “Decommissioning Information on Municipal Waste Disposal Grounds” • Survey. • Register. • End-Use.

  8. Saskatchewan Environmental Code Landfill Chapter • Closure required if landfill no longer accepts waste or has not accepted waste for at least two consecutive years. • Closure by following either the Acceptable Solutions or proposing Alternative Solution. • Closure requirements dependant upon site sensitivity.

  9. Stormwater Guidelines (2014) • Guidance with respect to stormwater management and water quality. • Closure systems to address long-term post-closure storm water. • Off site discharge of storm water. Use of sediment fore bays and pond structures.

  10. Steps to Final Closure

  11. Closure Plan • Notification of closure. • Report years site in operation and quantity of waste in place. • Schedule for completion of closure works. • Identify site sensitivity / receptors. • Site cleanup. • Address storm water, leachate, landfill gas, and erosion control measures. • Final contours and cover system design concept. • Buffer zones and compliance boundaries. • Water balance / long term-leachate generation. • Decommissioning of facilities. • Estimation of contaminating lifespan.

  12. Estimation of Percolation Leachate Generation Erosion and Slope Stability Cost Surface Water Runoff onto Adjacent Lands Selection of Landfill Cover Components Risk Assessment Receptors Long-Term Performance & Durability Spatial Constraints Material Availability

  13. Components of Closure Systems

  14. Grading • Grading a key component in landfill closure often not given its due. • Slopes typically between 5 and 33 percent. • Settlement of 10 percent (or more) of total waste height should be expected. Differential settlement common. • Crest slope critical. • Drainage from slopes.

  15. Types of Cover Systems • Numerous types of landfill cover systems have been developed. • Suitable cover system options are site specific based upon numerous factors.

  16. Roles of Cover System Components

  17. Clay Cover Systems Readily constructible. Low capital cost (if suitable material available) Approvals well defined. Susceptible to shrinkage cracking and/or freeze/thaw cycles. May have higher permeability than base liner. May be susceptible to differential settlement.

  18. Evopotranspiration Covers Climatic specific. Suitable for semi-arid environments only. Not significantly impacted by drying or freeze/thaw cycles. May be more effective than compacted clay covers. Design and regulatory approvals more intensive. Suitable soils required.

  19. Composite Cover Systems Excellent performance with very low infiltration rates possible. Suitable for high sensitivity. Not affected by freeze/thaw or drying. Decreased profile depth. May have higher capital costs relative to clay. Design and regulatory approvals may be more intensive. Require specialized installation and QA/QC.

  20. Stormwater Management Manage, at a minimum the 1:25 year event. May be required to manage the 1:100 year event depending on site conditions and receptors. Balancing Act: Preserve hydrologic cycle and getting storm water off limit of waste area ASAP. Ongoing maintenance and inspection.

  21. Leachate Management Leachate Management ranges from natural attenuation to active treatment. Active treatment range from on-site treatment, wetlands, to pumping via force main to off-site treatment facility.

  22. Landfill Gas Management

  23. EnvironmentalMonitoring Monitoring performance of environmental controls, and closure systems. Groundwater Surface water Soil gas

  24. Post-Closure Plan • Address long-term site inspection, monitoring and maintenance. • Address post-closure reporting and record keeping requirements. • Ongoing post-closure care through “Contaminating Lifespan” of site.

  25. Elements of Post Closure Care

  26. Financial Considerations

  27. Financial Considerations • Contaminating Lifespan • Post Closure Liabilities • Closure Costs • Maintenance, Monitoring and Reporting Costs • Contributions to Reserves. • Financial Analysis

  28. Contaminating Lifespan • How long before I can walk away from a landfill site? • The “minimum 25 year” catch. • Termination of post-closure care when: • Contaminants of concern do not exceed background concentrations. • Waste stabilization. • Actual landfill contaminating lifespan may be significantly longer than 25 years.

  29. Post-Closure Liabilities • Ongoing maintenance of landfill environmental controls (cover system, surface water controls, etc.). • Leachate treatment and disposal for sites with leachate collection systems. • Ongoing environmental monitoring and annual reporting. • Contingency reserve to address the unforeseeable.

  30. Closure Costs Final cover and stormwater management system / closure costs are highly variable and dependant upon numerous factors including: • Site sensitivity (environmental receptors); • Site geology and topography; • Meteorological conditions; • Material availability; and • Spatial constraints.

  31. Closure Costs – Part 2 So how much ??? • $15-35 per square meter for compacted clay cover systems when materials readily available, low sensitivity. • $40-50 per square meter for compacted clay covers systems when material scarce or high sensitivity. • $50-80 per square meter for geosynthetic composite covers for high sensitivity areas where “entombment” is required.

  32. Financial Assurance • Currently only required for non-municipal landfills. • Under proposed Environmental Code, Landfill Chapter, financial assurances would be required for all privately owned landfills as part of permit by end of the five-year phase-in period.

  33. Closure / Post-Closure Reserves • Planning for landfill closure is a lot like planning for your retirement!! • Start early. • Be conservative with length of contaminating lifespan. • Account for closure, post-closure activities, and a contingency fund to replace the house roof. • How much to stash away per year into a reserve fund? • Life cycle cost analysis.

  34. “Rule of Thumb” Stuff If all else fails…. • $4 to $6 per tonne is a good place to start, depending upon size of site and time until closure. • Post-closure monitoring - $25,000 to $50,000. • Post-closure maintenance - $25,000 • Leachate management and disposal – current unit costs.

  35. Life Cycle Cost Analysis • Cradle to Crypt approach to financial analysis of a landfill typically employs a LCA methodology. • Used to evaluate tipping fees. • Takes into account the following: • Remaining Airspace/Site Life; • Operating, expansion and closure costs; and • Post-closure liabilities. • Answers the question, “does the present tipping fee structure financially support ongoing operation, development, closure and post-closure liabilities for the landfill site”.

  36. Closure Example • Rural attenuation landfill. • Low sensitivity. • Existing GW monitoring wells (3). • No storm water infrastructure. • Attenuation (unlined) site. • Closure area of 1.2 hectares. • Topsoil stockpiled on site. • Readily available clay barrier soil. • Some regrading required to achieve 3H:1V (33 percent) slopes.

  37. Closure Costs

  38. Post Closure Liabilities

  39. Thank You!!

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