1. G3 – Environmental Geomechanics (Dr Sam Yuen)
Introduction to Civil Engineering
G3 – Environmental Geomechanics (Dr Sam Yuen)

2. Common Examples of Geotechnical Engineering
Landslide and Ground Subsidence
Earth Retaining Structures
Land Reclamation
Ground Improvement
Foundations
Excavation
Dams
Tunnels and Underground Space
Mining
Environmental Geomechanics

3. Geotechnical Engineering
Ground
Soil Groundwater Rock
Natural Environment

4. Video – Introduction to Sanitary Landfill

5. Sources of Potential Pollutants from Landfills

6. (Highly polluted water)
Sources of Pollutants
Completed Landfill (Long-Term)
Landfill Gas
(CH4 & CO2)
Waste
landfill Gas
Landfill Gas
Leachate
(Highly polluted water)

7. Landfill Design Concept

8. Natural Attenuation Landfills
Low permeability stratum
(e.g. heavy clay)
Cover
Waste
Siting landfills in low permeability geological setting
Attenuate contaminant migration through natural geological barriers

9. A Typical Containment Landfill
Capping
Waste
Landfill Gas
Extraction Well
Liner
Leachate Collection
System

10. Liner Compacted clay Clay with admixtures ( e.g. bentonite, fly ash)
Composite liners (using geosynthetics with clay layer)

11. Capping Design Compacted clay or composite layers (with geosynthetics)
Top soil supports vegetation to prevent erosion
Designed to tolerate settlement

12. Leachate Collection System Design
Leakage rate through liner proportional to leachate head

13. Site Selection

14. Site Selection Environmental Impact Studies (EIS)
Economic
Social
Environmental/ Engineering

15. Site Selection (continued ) Hydrogeological Assessment
Site geology
Permeability of geological material
Structural discontinuity
Groundwater hydraulic gradient
Geological material attenuation capacities
Surface water
Water chemistry