1. Part 2: LFG Generation - 1 -

2. LFG Generation Factors that affect LFG generation: Waste Management and Processing Variables: • Baling of waste • Shredding and crushing Design: • Landfill dimensions (area and depth) • Gas containment (liner and cover) • Gas extraction system - 2 -

3. LFG Generation Factors continued… Landfill Operations: • Day-to-day refuse handling • Degree of compaction or segregation • Cover characteristics • Degree of material breakdown • Liquid Addition • Managed (liquid additions and leachate recirculation) • Natural (precipitation and groundwater infiltration) • Post-closure changes (infiltration and leachate movement) - 3 -

4. LFG Generation Factors continued… Waste Composition: • Organic content (%) • Proportion of organics (food, paper, and wood) • Rate of decomposition Biological Factors: • Moisture (quality, seasonal, and movement) • Nutrients (availability and movement) • Bacteria (location, density, and mobility) • pH • Temperature - 4 -

5. LFG Generation Factors continued… It is difficult to predict the rate, extent, and timing of LFG generation. Some of the uncertainties include: • Waste placement (history, location, and composition) • Moisture content (significant effect on LFG production) • Biological parameters (nutrients, temperature, and pH) • LFG collection efficiencies - 5 -

6. LFG Generation - 6 -

7. LFG Generation Steps for assessing LFG generation potential: STEP ONE: LFG Modelling – exponential decay model typically used to: • Determine size of LFG collection systems • Estimate gaseous emissions to the environment • Evaluate the benefits of LFG utilization Example: Landfill Gas Emissions Model a.k.a. LandGEM developed by US EPA • Automated tool for estimating emission rates for total LFG, methane, carbon dioxide, etc. from municipal solid waste (MSW) landfills • Available for free download from US EPA’s Technology Transfer Network website at: www.epa.gov/ttn/catc/products.html - 7 -

8. LFG Generation Typical LFG Modelling Input: • Year landfill opened • Landfill closure year • Waste design capacity • Waste acceptance rate • k value: methane generation rate (default = 0.05) • Lo value: potential methane generation capacity (default = 170 m3 CH4/tonne of MSW) • Methane content (default = 50%) - 8 -

9. LFG Generation Typical LFG Modelling Output: - 9 -

10. LFG Generation STEP TWO: LFG Extraction Testing – involves installing one or more extraction wells and monitoring probes in the refuse. Used to measure: • Gas pressure • Gas composition distribution • Zone of influence • Extent of air intrusion - 10 -

11. LFG Generation Typical LFG Extraction Test Set-Up - 11 -

12. LFG Generation Typical LFG Extraction Test Layout - 12 -