This document is a lecture on landfill gas management by Prof. M.R. Ezhilkumar from Sri Krishna College of Engineering and Technology. It discusses the stages of landfill gas generation, composition of landfill gas, methods for estimating gas production rates, techniques for enhancing gas generation, and systems for controlling landfill gas migration. It provides details on the design of landfill gas collection systems, including the layout of gas extraction wells and headers, sizing calculations, and rules of thumb. Passive and active landfill gas control methods are also covered.

1. Prof. M.R.Ezhilkumar
Assistant Professor
Department of Civil Engineering
Sri Krishna College of Engineering and Technology
Coimbatore
ezhilkumar@skcet.ac.in
I only feel angry when I see waste.
When I see people throwing away
things we could use. – Mother
Teresa
1
17CE413
SOLID AND HAZARDOUS
WASTE MANAGEMENT
3.3 – Landfill gas management

2. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 2
Learning Outcomes
☼ Landfill gas
☼ Generation
☼ Movement
☼ Control
3.3 – Landfill gas management

3. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 3
Video Session

4. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 4
Landfill Gas
Stages of Gas Generation
I. Aerobic
II. Anaerobic, non-
methanogenic (acid
anaerobic)
III. Anaerobic,
methanogenic, unsteady
IV. Anaerobic,
methanogenic, steady

5. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 5
Landfill Gas
Stoichiometric Estimate of Potential
Gas Potential
Biochemical Methane Potential

6. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 6
Landfill Gas
Problems with Stoichiometric Estimates
 Some fractions are not biodegradable (lignin, plastics)
 Moisture limitations
 Toxins
 Some fractions are not accessible (plastic bags)

7. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 7
Landfill Gas
Estimates of Gas Production Rates
 Rapid degradation conditions: 3 to 7 years (4 to 10 L/kg/yr)
 Moderate degradation conditions: 10 to 20 years (1.5 t 3 L/kg/yr)
 Slow degradation conditions: 20 to 40 years (0.7 to 1.5 L/kg/yr)

8. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 8
Landfill Gas
Gas Enhancement Techniques
 Moisture Content
 Shredding
 Leachate Recycle
 Inoculum Addition
 Buffer
 Nutrient Addition
 Temperature

9. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 9
Landfill Gas
Gas Composition - Major Gases
 Methane (45 - 60 % by volume)
 Carbon Dioxide (40 - 60 % by volume)
 Nitrogen (2 - 5 % by volume)
 Oxygen (0.1 - 1.0 % by volume)
 Ammonia (0.1 - 1.0 % by volume)
 Hydrogen (0 - 0.2% by volume)

10. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 10
Landfill Gas
Gas Composition - Trace Gases (less than 0.6 % by volume)
 Odor causing compounds
 Aromatic hydrocarbons
 Chlorinated solvents
 Aliphatic hydrocarbons
 Alcohols
 Polyaromatic hydrocarbons

11. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 11
Landfill Gas
Why Bother with Landfill Gas?
 Odor
 Toxics
 Greenhouse Gas
 Explosive Gas
 Potential Energy Source

12. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 12
Landfill Gas
Landfill Gas Management
 • Containment
 – Natural barriers
 High groundwater table
 Streams/Waterbodies tied to
groundwater
 Impermeable geologic strata
 – Manmade barriers
 Composite liner
 Composite cover
 Cutoff walls
 Negative pressure trenches
 Positive pressure systems
(Brewers Stadium)

13. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 13
Landfill Gas
Landfill Gas Management
 Landfill Gas Collection Systems
 – Components
• Gas extraction wells or
trenches
• Gas extraction well heads
• Gas header pipes
• Condensate management
• Drip legs
• Condensate knockouts
• Control valves
• Blower station
• Flare (open or closed)

14. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 14
Landfill Gas
Components of Gas Recovery System
 One or more wells placed within the refuse
 A header system to connect the wells to the gas pumphouse system creating
the suction
 A flare system providing the opportunity to combust the landfill gas in the event
that the gas is not needed
 An end user of the gas

15. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 15
Landfill Gas
Landfill Gas Management
 Landfill Gas Collection Systems (continued)
 – Objective of system
• Migration control
• Regulatory compliance
• Energy recovery “$”
• Listen to clients needs
• Always consider health and safety

16. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 16
Landfill Gas
Landfill Gas Management
 Landfill Gas Collection System Design Steps
 – Consider objectives
 – Define limits of landfill
• Horizontally and vertically
 – Gas extraction wells or trenches
 – Layout gas wells
• Shallow wells - small ROI; • Deep wells - large ROI
• Typically 150’ ROI (per NR 500); • Liquid levels in landfill

17. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 17
Landfill Gas
Landfill Gas Management
 Landfill Gas Collection System Design Steps (continued)
– Locate gas header pipe
– Establish condensate management
– Adjust gas wells, if needed
– Prepare a well schedule (example)
• 0.5 to 1.5 cfm/slotted foot of pipe
– Determine gas generation and flow

18. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 18
Landfill Gas
Landfill Gas Management
 Landfill Gas Collection System Design Steps (continued)
– Header and blower sizing calculations
• Calculate by hand
• Spreadsheet
• Computer model KY GAS (Hardy cross method)
– Condensate calculations
– Select blower flare system

19. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 19
Landfill Gas
Landfill Gas Management
 Rules of Thumb for Header Design
• A velocity of 50 feet per second is the maximum allowed during concurrent
flow conditions
• A velocity of 30 feet per second is the maximum allowed during
countercurrent flow conditions
• A velocity of 30 feet per second is the maximum allowed within condensate
management structures
• A pressure drop of 1 inch water column per 100 feet of header is the
maximum allowed under any flow conditions

20. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 20
Landfill Gas
Landfill Gas Management
 Rules of Thumb for Header Design (continued)
• Flow conditions within a header must not exceed either pressure loss nor
velocity limitations
• 10 inches of vacuum required at furthest extraction well
• 10 to 20 inch loss of vacuum at blower flare station

21. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 21
Landfill Gas
Landfill Gas Migration - Wells

22. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 22
Landfill Gas
Landfill Gas Migration - Trench

23. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 23
Landfill Gas
Passive systems

24. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 24
Landfill Gas
Passive Landfill Gas Control

25. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 25
Landfill Gas
Landfill Gas Control

26. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 26
Landfill Gas
Landfill Gas is Typically Extracted to a Blower-Flare Station

27. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 27
Landfill Gas
Gas Extraction Wells
 Vertical piping system: installed following the refuse placement
 Horizontal piping system: installed as the refuse is placed
 Design considerations
• Spacing: zone of influence - apparent zone of vacuum influence around
a well
• Location: site topography, age of refuse, and system expansion over
time
• Depth: refuse depth, leachate mound, and cell construction

28. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 28
Landfill Gas
Gas Extraction Wells
 Factors affecting performance of gas extraction system
 Daily cover
 Elevated or perched liquids
 Shallow depth
 Sludge or liquid depth
 Permeability of final cover

29. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 29
Landfill Gas
Gas Extraction Wells
 Passive Wells (wells open to
atmosphere)
 Active Wells (wells connected
to a gas extraction system).

30. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 30
Landfill Gas
Vertical Piping System

31. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 31
Landfill Gas
Equilateral Triangular Distribution

32. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 32
Landfill Gas
Types of Collection Wells: Vertical wells

33. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 33
Landfill Gas
Condensate collection and Pump Station
 Landfill gas condensate – as gas cools while it is transported through the gas
collection system a liquid is formed (cutting of vacuum to the wells), separated
from gas flow and collected in the low spots of the system
 Pumping station reservoir – condensate forced to drain into it from low spots

34. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 34
Landfill Gas
Gas Treatment Methods
 Gas flaring – controlled combustion unit, reduces odors and more
environmentally sound than passive venting, enclose flares more efficient than
open flares
 Gas processing and energy recovery – gas processed by removing water,
carbon dioxide, and other impurities

35. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 35
Landfill Gas
Oxidation of Methane in Landfill “Bio Cover” (by Methanotrophs)

36. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 36
Landfill Gas
Oxidation of Methane in Landfill “Bio Cover” (by Methanotrophs)

37. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 37
Landfill Gas
Factors affecting gas generation

38. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 38
Landfill Gas
Comparison of Biodegradation Time

39. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 39
Assessment Time
Review
Question
Recommend a suitable landfill gas management

40. SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 40