1. Dr. Rehab O. Abdel Rahman
Associate Professor, AEAE
alaarehab@yahoo.com

2.  Liner selection
 Leachate collection system
 Gas collection system
 Monitoring
 Closure and post closure plan

3. Design Objectives
 Low hydraulic conductivity to minimize leakage (K ≤
10-7 cm/sec)
 Adequate shear strength to maintain liner stability
under landfill weight and loads from vehicular
movement
 Minimal shrinkage potential to minimize desiccation
cracking
 Chemical stability for reactions with the waste or
leachate

4. Materials
 Soils, such as benotnite, compacted clay
 Admixes such as asphalte concrete, asphalte
membrane, soil cement
 Polymer such as geotextile, geomembrane
 Organic and inorganic bases and hydrocarbon
pollutant will eliminate some polymer and soil
asphalt
 Limited Budget use soil or soil cement or asphalt liner,
some polymer
 Membrane (asphalte, polymer ) are medium cost

6. Clay advantage
 Low cost
 High cation exchange capacity
 Resist leachate migration
 Low Ks, due to
◦ Small size
◦ Compact soil fabric
 Good geomechnical properties, i.e.
Toughness, Dilatancy, Plactiticty
Disadvantage clay
 Dissolution may occur due to the
acidity of leachate

7. Types of liner
 Single
 Single composite
 Double composite

9. Located at the bottom of the landfill above liner
1) Drainage layer
 Highly permeable layer to ease lateral drainage of
leachate
 Its thickness > 30 cm
 Permeability  0.001 cm/sec
2) Sloped terrace
To increase the potential to lateral migration of leachate
(2% slope)

10. 3) Perforated pipes
 To collect and drain the leachate 10 cm D HDPE or PVC
pipes with perforation of 1 cm in the upper three
quarters
4) Filter layer
 An inverted filter used to prevent clogging of pipes due
to sand ingression from drainage layer
5) Sump well
 Used to pump out the leachate collected at the bottom
of the landfill

11.  After collection, leachate is treated using
 Biological treatment (aerobic- anaerobic)
 Physical and chemical treatment (flocculation –
sedimentation-filtration- sorption)

12.  Leachate leakage may occur from the bases or sides of
landfill due to
1) Joint failure or puncture of geo-membrane liner
2) Cracks in the clay liner
3) Excessive pressure build up in the landfill
 How to calculate leachate flow in disposal
Use darcy law Q=KiA
1) Q amount of leachate (m3/d)
2) K hydraulic conductivity (m/d)
3) i hydraulic gradient (h1-h2)/l
4) A area of landfill (m2)

13.  Gases generated in landfill
◦ Methane
◦ Carbon dioxide
◦ Nitrogen
◦ oxygen
◦ Hydrogen
◦ Hydrogen sulfide
◦ Carbon monoxide


14.  Potential environmental impact of landfill gases
◦ Explosion
◦ Asphyxiation,
◦ Vegetation damage
◦ Water pollution
◦ Corrosion
◦ Nuisance
 Methane is lighter than air
 Carbon dioxide is heavier than air

15. Factors affect gas generation
 Moisture content
 Waste type
 Nutrient content
 Specific weight
 Ph
 Temperature
 Particle size

16.  to prevent migration of gas to the nearby areas
 it as an energy resource,
Components of Gas Collection System
 Gas wells placed within the wastes
 Header system to connect the well to the gas Pumping
unit
 Gas purification system
 Energy recovery Plant

18.  Double liner System-at the base and sides of the landfill
to prevent migration of leachate to the surroundings
 Leachate Collection and Treatment Facility-to collect
leachate from the base of the landfill for treatment to meet
regulatory standards
 Gas Collection and Treatment Facility-to collect gas
emanating from the landfill and to treat
 Final Cover-at the top of landfill to prevent infiltration of
water into the landfill and to support vegetation.

19.  Surface drainage System-to collect and
divert all surface runoff from the landfill
 Environmental Monitoring Plan-for periodic
monitoring of environmental quality of air, surface
water, groundwater, vadoze zone.
 Closure and Post-closure Plan details of activities to
be undertaken to close a landfill site once the filling
operation has been completed and for monitoring
and maintenance of the completed landfill.