CONTAINMENT CONTROL SYSTEMS

Containment control system 1.Leachate collection system2.Gas collection systems• Liner and Cover- Control movement of leachate &

landfill gases

Engineered Containment

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

Components of cover system

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

• SINGLE LAYER SYSTEMS

• SINGLE COMPOSITE LINER SYSTEM

• DOUBLE LINER SYSTEM

TYPES OF LINER SYSTEMS

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

LANDFILL LINERS

1. Rigid liners2. Flexible liners

1. RIGID LINERS

A. Cement GroutB. Cement ConcreteC. Soil cementD. Bituminous concreteE. Bitumen Panels

a. Cement Grout

• Cement: sand 1:4•W/c 0.4-0.6• Sides & bottom grouted

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

Rigid Panels

Flexible Panels

Tessman Rd. Landfill, Houston Tx

Winner of the 2010 SWANA Gold Excellence Award for Landfill Secondary Use

Questions