Landfills

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Landfills

• Discussion 24
• Soils and Environmental Quality

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Options for Controlling Municipal Solid Waste
(MSW)

• Recyling
• Incineration
• Composting and landspreading
• Landfills

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What is a Secure Landfill?

• A carefully engineered depression in the ground
  or build on top of the ground into which waste
  are put, i.e., a bathtub in the ground
• Composition
• A bottom liner
• A leachate collection system
• A cover
• A compatible hydrogeologic setting

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Example of a Landfill
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Landfill Dropoff
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Some Basic Facts Re Landfills

• In the USA 55 of the MSW (after recyling) is
  disposed in a landfill
• The USA has 3091 active landfills over 10,000
  old municipal landfills

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Environmental Concerns Re Landfills

• Toxic leachates may contaminate surface-
  ground-water
• Release of noxious/combustible gases
• Accumulation of hazardous and low-level
  radioactive wastes
• Noise and visual pollution
• Others birds near airports

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Table 1. Concentration Ranges for Components of
Municipal Landfill Leachate
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Composition of Bottom Liners

• Clay smectitic clays 1 m thick optimum may
  crack or become degraded by chemicals
• Composite plastic (flexible membrane liners,
  FMLs) and compacted/clayey soil leakage common
• Plastic (HDPE) 100-mil (0.1 inch) synthetic
  flexible

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HDPE Landfill Liner
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Clogging of Leachate Collection Systems

• Silt or clay in lt10 yr
• Growth of microorganisms in pipes
• Chemical reactions and precipitates in pipes
• Weakening of pipes from chemical attack by acids,
  solvents, etc.

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Landfill Leachate Leakage
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Landfill Leachate Collection System
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Landfill Leachate Treatment
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Problems with Landfill Covers

• Erosion of topsoil, exposing MSW cells
• Roots from cover plants may penetrate MSW cells
• Ditto burrowing animals
• Sunlight may dry out clay cap, causing cracks
• Subsidence may cause cracks in cover
• Rubber tires may float upward
• Human activities of many kinds

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TYPICAL CONSTITUENTS AND COMPOUNDS FOUND IN
LANDFILL GAS TABLE 1  Typical Constituents Found
in Municipal Solid Waste Landfill Gas Component
                                          Percent
(dry volume basis) Methane                       
                            40-60Carbon
Dioxide                                  
     40-60Nitrogen                              
                         2-5Oxygen              
                                    
0.1-1.0Ammonia                                  
              0.1-1.0 Sulfides, disulfides,
mercaptans,etc.          0-0.2Hydrogen          
                                       
 0-0.2Carbon Monoxide                           
           0-0.2Trace Constituents              
                   0.01-0.6 Exact percentage
distribution will vary with the age of the
landfill.
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TABLE 2  Typical Concentrations of Some Trace
Compounds Found in Landfill Gas Component      
                                        Mean
Concentration (pbV, parts per billion by
volume) Toluene                                   
                   34,907Dichloromethane         
                                25,694Ethyl
Benzene                                           
    7,334Acetone                                 
                       6,838Vinyl
Acetate                                           
     5,663Tetrachloroethylene                    
                   5,244Vinyl Chloride           
                                    3,508Methyl
Ethyl Ketone                                     3
,092Xylenes                                      
                   2,6511,1-Dichloroethane       
                                 2,801Trichloroet
hylene                                           2
,079Benzene                                      
                  2,057 SOURCE G. Tchobanoglous,
H. Theisen and S. Vigil, "Integrated Solid Waste
Management, Engineering Principles and Management
Issues," McGraw-Hill, New York, 1993. Shown here
as reproduced in J.Wilcos, Ph.D., and W.Clister,
"Waiting is Over Landfills Have Clean Air Act
Rules," Solid Waste Technologies, March/April
1996. Provided by Dan Knapp of Urban Ore,
Berkley, California
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Case Study The Refuse Hideaway Landfill of
Middleton, WI

• The 23-acre Refuse Hideaway Landfill site was
  licensed by WDNR in 1974
• Landfill received municipal, commercial, and
  industrial wastes until 1988 when it was closed
  by court order
• Closure included a clay and soil cap and seeding
  a vegetation cover
• It was determined that soils, groundwater, and
  private wells were contaminated with VOCs, which
  constitute a health risk
• In 1989 the owner of the landfill declared
  bankrupcy
• In 1991 methane gas and leachate collection
  systems were initiated the landfill cap was
  repaired
• In October 1992 the area was declared an EPA
  Superfund site
• In 1995 a comprehensive cleanup plan included
  groundwater extraction and treatment to contain
  the contaminant plume

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For More Information

• http//www.zerowasteamerica.org/Landfills.htm
• http//people.howstuffworks.com/landfill7.htm
• http//gfredlee.com/lf-conta.htm