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Containment control system 1.Leachate collection system2.Gas collection systems• Liner and Cover- Control movement of leachate &
landfill gases
Steps for leachate control in landfills• Liner system: -Prevent leachate migration from sides
& bases to subsoil-Control damage of liner system-Minimization of leachate heads above
liner system• Drainage-Proper collection & removel of
leachate
COVER SYSTEMSFUNCTIONS:
1.Control runoff2.Separate waste from animals,
plants, insects, humans3. Prevent infiltration of precipitation
entry into waste4. Control release of gas from waste
A Typical Landfill Cap
Objective of final cover system is to improve surface drainage, minimize infiltration and support vegetation
1. SURFACE LAYER ( 40 to 100 cm)
FUNCTION:• Vegetation growth• Evapotranspiration• Prevent erosionCONSTRUCTION MATERIAL:Top soil, cobbles
2. PROTECTION LAYER
FUNCTION:• Store water• Prevent intrusion by plants,
animals etc• Protect barrier layer from freeze ,
thaw etcCONSTRUCTION MATERIAL:• Mixed soil, cobbles
3. DRAINAGE LAYER (100 to 150mm)
FUNCTION:• Drain away infiltrating waterCONSTRUCTION MATERIAL:• Sand, • Gravel, • Geotextiles,• Geonets,• Geocomposites
4. BARRIER LAYER( 200 to 300 mm)FUNCTION:• Prevent infiltration of water into waste• Escape of gas out of wasteCONSTRUCTION MATERIAL:• Clay liners• Geomembranes• Geosynthetic clay liners• Bentonite mix ovelain bt HDPE
membrane
5. GAS COLLECTION LAYER (150 t0 200 mm
FUNCTION:• Trasmit gas to collection pointsCONSTRUCTION MATERIAL:• Sand• Geotextiles• Geonets
LINER SYSTEMS• Leachate drainage, Collection layer,
Barrier layer• Low permeability, durable, resistant
to attack • Liner materials- -natural clays, -amended soil, -geomembranes, -geosynthetic clay
liners
1. SINGLE LAYER SYSTEMS
• One layer of impermeable material – to control leachate flow• Lining material : clay/amended
soil/geomembrane• Used for: -Nonreactive, non hazardous, non
biodegradable waste- Water table is deep
2. SINGLE COMPOSITE LINER SYSTEM
• Two or more layers of impermeable materials• Suitable for muncipal solid waste
3.DOUBLE LINER SYSTEM
• Two liners provided one over the other with sand layer sandwiched in between• Sand layer provided with network
of pipes –to collect leachate if any infiltrates into it from upper liner
Liner Requirements
• Hydraulic conductivity 10-7 cm/sec or less• Thickness 100cm or more• Adequate strength under
compressive loads & along side slope• Absence of clay clods• Absence of shrinkage cracks
Liner Specifications
Boynton & Daniel• % fines ≥ 20-30%• Platicity index ≥ 7-10%• % gravel ≤ 30%• Max particle size 20-50mm
• Bagchi• % fines 40-50%• Platicity index 10-30%• Liquid limit 25-30%• Clay content 18-25%
DOE• Plasticity 10-30%• Activity ≥ 0.3
Liner Design Aspects• Identification of borrow area & source of
materials• For in situ soil- Conduct field permeability
tests• Liner materials- Lab study• Source of additive materials• Additive mixes- Lab tests• Field trial test on test pads – to find
compaction parameters
1. RIGID LINERS
A. Cement GroutB. Cement ConcreteC. Soil cementD. Bituminous concreteE. Bitumen Panels
b. Cement Concrete Grout
• Cement + sand + Coarse aggregate• Reinforced with wire mesh or
reinforced bars
c. Soil Cement
• Cheap, naturally available• Cement + aggregate blended in
dry condition• Water added @ plant or after dry
mix spread on prepared surface
d. Bituminous Concrete
• Thickness 4cm to 15cm• Chemical compatibility b/w
landfill contents & bituminous material
5. Bitumen Panel
• Effective seepage control system• Disadv - Low strength
-High deformation characteristics
2. FLEXIBLE LINERS
a. Natural LinersCompacted clayChemically
treated/amendedsoilBentonite clay
b. Composite linersc. Synthetic liners
a. Natural Liners- Compacted soil Liners• Natural clay- liner material• If clay not available- Soil + bentonite ( amended soil)- used• Synthetic geomembranes
Flexible membrane with amended soilGeosynthetic clay liner
• Natural clay excavated or recompacted• If clay brought from nearby areas- spread
in layers & compacted
Construction aspects
• Clear borrow area- removal of shrubs etc• Adjust w.c in borrow area
Sprinkling/irrigating- increase w.cRipping/areation- Lower w.c
• Excavation of materials• Transportation- Haulers/ conveyor
systems• Spreading & levelling in thin layers
• Final wc adjustment by spraying & mixing water
• Compaction using rollers• Quality testing• Placement of next lift & process continued
• Lift thickness of clay liners 25-30cm• Sheep foot rollers for compacting lifts• Lift placed in horizontal layers• Lift placed parallel to slope (Side slope 2.5 H to
1 V)
b. Amended soil liners
• Low permeability clay not available-• In situ clay + bentonite ( medium –high
plasticity)-• achieve low hydraulic conductivity• High permeability clay + sodium bentonite-
Hydraulic conductivity less than 1x10-7cm/s• Well graded soil 5-10% by weight of bentonite• Uniformly graded soil 10-15% bentonite
Construction
• Similar to compacted clay liner• After excavation stage, additive is
introduced into the soil• Additives like bentonite introduced
in 2 ways:In plant MixingCentral plant mixing
• In central plant method,-Soil & additive mixed in
pugmill/ central mixing plant-Water added along with
bentonite or seperately• After compaction of lift, covered
with plastic sheet- to protect from dessication which results in cracking
• Contaminant transport-Transportation by advection/diffusion- studies need to be carried out• Chemical compatibility test need
to be conducted
3. Synthetic Flexible Liners• Polymeric Materials produced in sheets• Thinner, light weight, good quality
control, ease of installation, Cost effectiveness• Types of geosynthetics used:
Geotextiles,geomats,geospace,Geogrids, geonets, geocell, bonded geogrid,
geocomposite
1.PHYSICAL PROPERTIES• Thickness
0.25- 2.5mm• Specific gravity
0.9-1.5• Weight• Water vapour
transmisson1-10g/cm2 in 24
hrs
2.CHEMICAL PROPERTIES• Ozone resistance• U-V resistance• Chemical Compatibility
3. THERMAL PROPERTY• Durability in hot & cold
climate
Ground modification techniques
• Mechanical modification• Chemical Modification• Hydraulic modification
Liner systems other than Basal lining
1.Side lining system• Similar to basal lining system• Due to steepness of slope, prefabricated
products like geomembrane /geocomposite clay liners used
2.Draiange Blanket
• Thickness 0.3-0.5m, @ Bottom 16-32mm gravel
• Serves as leakage collection system• Maintain proper hydraulic head above liner• Divert leachate to collection pipes• Bottom provided with gently sloped gravel
trenches
3.Surface lining or top capping
• Surface lining:-Proper cover-prevent infiltration-Prevent intrusion of vegetation/animals-Resistant to external forces
Two Types of Solar Caps
Flexible solar panels Rigid panels
Low power production efficiency ca. 6%
Higher power production efficiency > 13%
Light Heavier (steel frame, glass)
Flexible, unbreakable Stiff frame
Works well with diffuse light
Less efficient with diffuse light
Works well with temperatures above 40°C
Less efficient with temperatures above 40°C
Tessman Rd. Landfill, Houston Tx
Winner of the 2010 SWANA Gold Excellence Award for Landfill Secondary Use