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Landfill Gas Management System

Milind V. Khire, Ph.D., P.E.Department of Civil & Environmental EngineeringMichigan State UniversityA135 Research Complex EngineeringE Lansing, MI 48824(517) 432-3130 khire@egr.msu.edu

Engineered Landfills – Key Components

Final Cap

Surface Water Management System

Gas Collection System

Liner and Leachate Collection System (LCS)

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Landfill Gas Constituents

• CH4

• CO2

• SO2

• H2S• Mercury (Hg)• VOCs• ?

Landfill Gas Regulations

• Explosive Gas Concentration at property boundary shall be < 5%

• Non Methanogenic Organic Compounds (NMOCs) shall be destroyed by 99.9% or more before releasing into the atmosphere

• These regulations only apply to medium or large size landfills

• Small landfills (< 2.5 Million Metric tons total capacity) are exempt from gas collection regulations. However, if neighbors complain about odors, small landfill owners need to collect and manage gas to mitigate odor problems.

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Landfill Gas Management System -Functions

• Collect and Remove Gas from the landfill for treatment and flaring or gas to energy conversion

• Reduces the risk of explosion of landfill• Reduces the risk of ground water and air

pollution from leakage or diffusion of landfill gas

• Odor Control

Essential Components of Landfill Gas Management System

• Vertical Wells or Horizontal Gas Collection Trenches

• Gas Header Pipe• Gas Blower• Condensate Trap• Flare (to burn methane and other non-

methanogenic organic compounds- NMOCs)• Gas to Energy Generator – not essential

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Basic Types of Gas Management Systems

• Passive Venting• Active collection and treatment/flaring

Passive Venting

~MSW ~

Gravel Pack

4 to 6” dia. PVC Conduit

(10 to 14’ high)

Concrete Pad or Seal

• In passive venting, gas is released to the atmosphere without treatment

• Gas comes out its own pressure without the need to apply suction to pull the gas out

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Active Gas Collection – Vertical Wells

~MSW ~Gravel Pack

4 to 6” dia. PVC Conduit

Suction (to blower)

Active Gas Collection – Vertical Wells

~MSW ~

Gravel Pack

4 to 6” dia. PVC Conduit Suction (to

blower)

• In passive venting, gas is collected and treated or flared• Gas comes out under the action of a small amount of

suction applied in the common leachate header pipe.

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Active Gas Collection – Trenches

~MSW ~

4 to 6” dia. PVC Conduit

Suction (to blower)

Landfill Gas Well and Header Pipe

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Landfill Gas Wells and Header Pipe

To Blower

Landfill Gas Well and Header Pipe

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Landfill Gas Manifold

Landfill Gas Condensate Trap

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Landfill Gas Flare

Landfill Gas to Electrical Energy Generator

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Leachate Evaporator Using Gas Energy

Puente Hills Panorama- 4 (middle right)

Note: Greenwaste area, industrial waste tipface, cover stockpile, high standard of cover in general

and odour dispersal fan (middle foreground)

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Puente Hills Panorama– 3 (middle)

Note: LFG pipework and main active face (centre)