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CONTAINMENT CONTROL SYSTEMS

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:

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CONTAINMENT CONTROL SYSTEMS

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  1. CONTAINMENT CONTROL SYSTEMS

  2. Containment control system 1.Leachate collection system 2.Gas collection systems • Liner and Cover - Control movement of leachate & landfill gases

  3. Engineered Containment

  4. 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

  5. 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

  6. A Typical Landfill Cap Objective of final cover system is to improve surface drainage, minimize infiltration and support vegetation

  7. Components of cover system

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

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

  10. 3. DRAINAGE LAYER (100 to 150mm) FUNCTION: • Drain away infiltrating water CONSTRUCTION MATERIAL: • Sand, • Gravel, • Geotextiles, • Geonets, • Geocomposites

  11. 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 ovelainbt HDPE membrane

  12. 5. GAS COLLECTION LAYER (150 t0 200 mm FUNCTION: • Trasmit gas to collection points CONSTRUCTION MATERIAL: • Sand • Geotextiles • Geonets

  13. LINER SYSTEMS • Leachate drainage, Collection layer, Barrier layer • Low permeability, durable, resistant to attack • Liner materials- -natural clays, -amended soil, -geomembranes, -geosynthetic clay liners

  14. TYPES OF LINER SYSTEMS • SINGLE LAYER SYSTEMS • SINGLE COMPOSITE LINER SYSTEM • DOUBLE LINER SYSTEM

  15. 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

  16. 2. SINGLE COMPOSITE LINER SYSTEM • Two or more layers of impermeable materials • Suitable for muncipal solid waste

  17. 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

  18. 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

  19. 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

  20. 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

  21. LANDFILL LINERS • Rigid liners • Flexible liners

  22. 1. RIGID LINERS • Cement Grout • Cement Concrete • Soil cement • Bituminous concrete • Bitumen Panels

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

  24. b. Cement Concrete Grout • Cement + sand + Coarse aggregate • Reinforced with wire mesh or reinforced bars

  25. c. Soil Cement • Cheap, naturally available • Cement + aggregate blended in dry condition • Water added @ plant or after dry mix spread on prepared surface

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

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

  28. 2. FLEXIBLE LINERS • Natural Liners Compacted clay Chemically treated/amendedsoil Bentonite clay b. Composite liners c. Synthetic liners

  29. 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

  30. 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

  31. 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)

  32. 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

  33. 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

  34. 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

  35. Contaminant transport-Transportation by advection/diffusion- studies need to be carried out • Chemical compatibility test need to be conducted

  36. 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

  37. 1.PHYSICAL PROPERTIES • Thickness 0.25- 2.5mm • Specific gravity 0.9-1.5 • Weight • Water vapourtransmisson 1-10g/cm2 in 24 hrs 2.CHEMICAL PROPERTIES • Ozone resistance • U-V resistance • Chemical Compatibility 3. THERMAL PROPERTY • Durability in hot & cold climate

  38. Ground modification techniques • Mechanical modification • Chemical Modification • Hydraulic modification

  39. 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

  40. 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

  41. 3.Surface lining or top capping • Surface lining: -Proper cover -prevent infiltration -Prevent intrusion of vegetation/animals -Resistant to external forces

  42. Two Types of Solar Caps

  43. Rigid Panels

  44. Flexible Panels

  45. Tessman Rd. Landfill, Houston Tx Winner of the 2010 SWANA Gold Excellence Award for Landfill Secondary Use

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