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Landfill Leachate

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LandfillLeachates in Landfills

    Nathan NarendranathanM.Eng.Sc., C.P.Eng

    Infratech Environmental

    AustraliaEmail: [email protected]

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    How do landfills perform?Landfills perform by controlling andmanaging the movements of fluids (i.e.liquids and gasses) around, into and out ofthe contaminated waste volume.

    Base barrier system functions:(1) To minimise the escape of

    leachate into the foundation(2) To prevent contamination of

    groundwater

    Cap barrier system functions:(1) To control moisture filtration

    into the waste(2) To collect gas flows from the

    waste(3) To prevent odours, and

    sources of disease(4) To meet erosion, aesthetic and

    other functional criteria

    Rainfall

    Cap barrier

    systemGas Flow

    Leachate flowContained waste

    Foundation

    Base barrier

    system

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LAND FILL WATER BALANCEPrecipitation

    Evapotranspiration

    Percolation into Waste

    SurfaceRunoff

    Surface

    Runoff

    Leachate

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Precipitation

    Run off

    Vertical Percolation

    Topsoil

    Rooting Layer

    BarrierLayer

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE GENERATION

    ASSESSMENT OF

    QUANTITY &

    QUALITY

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE QUANTITY

    PRECIPITATION

    GROUND WATER INFLUX

    WASTE MOISTURE CONTENT

    FINAL COVER DESIGN

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    WHY LEACHATE QUALITYASSESSMENT

    WASTE HAZARD IDENTIFICATION

    CHOOSE LAND FILL DESIGN

    LEACHATE TREATMENT PLANT DESIGN

    FORMULATE GROUND WATER

    MONITORING PARAMETERS AND REGIME

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    APPROACHES

    NORMALLY WASTE CHARECTERISATIONWILL PRECEDE

    LAB TESTS BULK TEST, TCLP

    FIELD TESTS LYSIMETER ETC.

    PREDICTIVE MODELLING

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE QUANTITY

    PRECLOSURE RATE

    POST CLOSURE RATE

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    SOME FACTORS

    COVER OR NOT TO COVER HOW LONG BEFORE TREATMENT IS NEEDED? 10,

    20, 40 YRS.?

    CLIMATIC CONDITION

    OPERATION OF LANDFILL

    WASTE COMPOSITION

    ELAPSED TIME

    AMBIENT TEMPERATURE AVAILABLE MOISTURE , OXYGEN

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Leachate

    Leakage CollectionPipe

    LinerCollection

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    PLAN VIEW

    Cleaning Port

    To Tank

    AA

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    NAL

    Landfill

    Clay Stratum

    Sandy Aquifer

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Water flow Direction

    GWT

    Bedrock

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    Leachate Collection Pipes

    Clay Liner

    Compacted Subbase

    Drainage Blanket

    SyntheticMembraneLiner

    Double lined landfill with a single collection system: scheme 1

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    Double lined landfill with a single collection system: scheme 2

    Clay Liner

    Leachate Collection Pipes

    Drainage Blanket

    SyntheticMembrane

    Liner

    Compacted Subbase

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    scheme 3 Leachate Collection Pipes

    Drainage Blanket

    ClayLiner

    BentoniteAmendedSoil liner

    Compacted Subbase

    Double lined landfill with a single collection system: scheme 3

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    Scheme 1

    Leachate Collection Pipe

    Drainage Blanket

    SyntheticMembrane

    Liner

    Compacted Subase

    Multiple lined landfill with two collection systems

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    Scheme 2

    Leachate Collection Pipes

    Drainage Blanket

    Synthetic

    MembraneLiner

    Clay Liner

    Compacted Subbase

    Multiple lined landfill with two collection systems

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

    Drainage Blankets

    CompositeLiner

    ClayEquivilantLiner

    Subbase Replaced with Compacted

    Bentonite Amended Soil or Clay Liner

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE COLLECTION

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    STORM WATER MANAGEMENT

    STORM WATER DITCHES

    CULVERTS & MANHOLES

    STORM WATER BASINS

    SEDIMENTATION TANK

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    DRAINAGE FOR LEACHATE

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    LEACHATE PONDS

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Leachate Drainage Layer

    Must have adequate capacity to handle the maximum flowproduced during landfill operations.

    Can use granular materials, with hydraulic conductivity1*10^(-3) m/sec, or a geocomposite drain.

    Design of drainage layer needs to consider clogging when

    (1) High pH liquids(2) More than 2,500 g/ml of TDS or BOD

    Network of perforated collection pipes (usually HDPE) carryleachate out of drainage layer.

    Do not place geotextile filter directly around pipes(clogging)

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Geocomposite Drainage Layers

    Geonet drainage layer between two layers of non-wovengeotextile filters.

    Design is based around equivalency with granular drainage

    layer, with lab testing to ensure adequate flow rates under

    weight of waste.

    Lab testing needs to simulate the intrusion of the geotextile

    filter into the geonet core, and the compressive creep of the

    geonet.

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Geonets

    Bi-planar geonets commonly used in small landfills. Tri-planar geonets withstand a greater compressive stress

    (important for large depths of waste).

    Transmissivity under 1000 kPa can be half the

    transmissivity under 100 kPa.

    Use relatively high factor of safety (build up from partial

    factors)

    W k h N T h l i f C ff i L dfillM KL 7J l 2004

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Geotextile Filters

    Pore opening size needs to be small enough to prevent fineparticles entering the geonet drainage core, whilst large

    enough to allow adequate flow under compressive stress

    and potential clogging.

    Use a relatively high factor of safety (build up from partial

    factors).

    W k h N T h l i f C t ff ti L dfillM t KL 7J l 2004

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Leachate Collection and Removal

    System comprises leachate filter and drainage layer,perforated collection pipes, sumps, riser pipes, pumps and

    leachate storage ponds or tanks.

    Sub-base must be sloping (minimum 2%).

    Pipes should be spaced and sized for the required flow andmust be strong enough for the weight of the overburden of

    waste (design examples given in Qian et al, 2002).

    Unusually large rainstorm events can sometimes bedifficult to cope with.

    WorkshoponNew Technologies forCost effectiveLandfillManagement KL 7July 2004

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    Workshop on New Technologies for Cost-effective Landfill Management, KL. 7 July 2004

    Geotextile Durability

    ASTM test for long term immersion in leachate underelevated temperature.

    Tests carried out with Hong Kong leachate indicated that

    HDPE and polypropylene geotextiles had a good long term

    resistance to our leachate, but polyester geotextiles had alower resistance.


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