EXPOSED GEOMEMBRANE COVER SYSTEMS

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EXPOSED GEOMEMBRANE COVER SYSTEMS

• FOR SUBTITLE D LANDFILL CLOSURES

Presented by John W. Hurford, P.E.
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EXPOSED GEOMEMBRANECOVER SYSTEM

• The Exposed Geomembrane Cover System (EGCS) is a
  polymer material available in a variety of
  materials, colors, thicknesses, and densities.
• All choices are site specific based on
  application and aesthetics.
• The fundamental advantage is construction and OM
  cost savings.

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MATERIAL OPTIONS

• Polymers
• High Density Polyethylene (HDPE)
• Linear Low Density Polyethylene (LLDPE)
• Surface Features
• Smooth or Textured
• Colors
• Black, Green, or White

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POTENTIAL SAVINGS

• The EGCS closure design provides a long term
  durable closure option at significantly reduced
  costs
• Final cover soils are eliminated
• Construction/installation costs are reduced by
  25K to 50K per acre.
• Long term Operational and Maintenance cost are
  reduced

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OTHER ADVANTAGES

• Reduced hydraulic head on the geomembrane
• Improved slope stability
• Enhanced visual inspection
• Valuable Air space is retained

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INSTALLATION HISTORY

• First installed in Delaware 1992
• Installed in Maine in 1996
• Final GREEN closure in Delaware 1997
• Installed in Louisiana 1999
• Multiple installations in Florida 1999 to Present
• Marion County Baseline
• New River Tri-County
• Polk County North Central

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EXISTING INSTALLATIONS
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EXISTING INSTALLATIONS
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EXISTING INSTALLATIONS
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SPECIAL APPLICATIONS

• The material is especially suitable for
  applications of step side slopes
• Where cover soils are impractical or cost
  prohibitive
• Extremely useful where vertical expansion or
  reclamation is planned allowing for easy reentry
  after interim closure

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SPECIAL APPLICATIONS
New River Bioreactor Well Heads

• Particularly useful in Bioreactor applications
• Conforms easily to settling top surfaces and side
  slopes
• Easily adjusted around gas collection
  infrastructure including well heads, collection
  headers and/or subsurface geonets
• Lay infrastructure above membrane

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SPECIAL CONCERNS

• Wind and/or Gas Uplift Various anchoring
  systems available maintain vacuum under liner.
• Storm Water Runoff No silt but increased
  volume. Requires well designed collection and
  conveyance system around base.

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SOME CONCERNS

• Environmental Damage
• Sunlight (2 Carbon Black)
• Extreme Temperatures (USEPA Freeze/Thaw Test)
• Vandalism, Animals
• Limited Access and Post Closure Use No vehicles
  or grazing animals
• Aesthetic Concerns
• Potentially limited design life (2005 GRI
  Progress Report indicates HDPE likely greater
  than 30 years)

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CLOSURE CONNECTION
CROSS SECTION WHERE TOP AND BOTTOM LINERS MEET
WELDED JOINT
TYPICAL TRENCH INSTALLATION
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QUESTIONS ?