CONTAINMENT CONTROL SYSTEMS

Containment control system 1.Leachate collection system 2.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

2.Separate waste from animals, plants, insects, humans COVER SYSTEMS FUNCTIONS: 1.Control runoff 2.Separate waste from animals, plants, insects, humans 3. Prevent infiltration of precipitation entry into waste 4. 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

CONSTRUCTION MATERIAL: Top soil, cobbles 1. SURFACE LAYER ( 40 to 100 cm) FUNCTION: Vegetation growth Evapotranspiration Prevent erosion CONSTRUCTION MATERIAL: Top soil, cobbles

Prevent intrusion by plants, animals etc 2. PROTECTION LAYER FUNCTION: Store water Prevent intrusion by plants, animals etc Protect barrier layer from freeze , thaw etc CONSTRUCTION MATERIAL: Mixed soil, cobbles

3. DRAINAGE LAYER (100 to 150mm) FUNCTION: Drain away infiltrating water CONSTRUCTION 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 waste CONSTRUCTION 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 points CONSTRUCTION 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

TYPES OF LINER SYSTEMS SINGLE LAYER SYSTEMS SINGLE COMPOSITE LINER SYSTEM DOUBLE LINER SYSTEM

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 Rigid liners Flexible liners

1. RIGID LINERS Cement Grout Cement Concrete Soil cement Bituminous concrete 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

Chemical compatibility b/w landfill contents & bituminous material d. Bituminous Concrete Thickness 4cm to 15cm Chemical compatibility b/w landfill contents & bituminous material

Effective seepage control system Disadv - Low strength 5. Bitumen Panel Effective seepage control system Disadv - Low strength -High deformation characteristics

2. FLEXIBLE LINERS Natural Liners Compacted clay Chemically treated/amendedsoil Bentonite clay b. Composite liners c. 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 soil Geosynthetic 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.c Ripping/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 Mixing Central 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 transmisson 1-10g/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 -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

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