Lesson 12: MSW Landfills

Stormwater Control

Read: Text, Chapter 4 (pp. 151-154)

• Used to limit infiltration (leachate production) by increasing runoff during the active phase of landfilling.
• Thicker and more permanent than daily cover
  • Daily cover is typically no more than 12" and is used to limit vectors, odor, and litter
• Typically severa feet of material
  • This material is generally whatever soil is available on-site but, the soil may also be obtained from borrow pits.
  • Alternatives to soil cover include compost, powdered rubber (from used tires), thickly applied proprietary materials including foams, polymers, clay/newsprint composites.
  • Some sites have considered using geomembranes which could be recovered prior to placing waste again.  This technique has been hampered by an inability to secure the geomembrane without placing materials on it.  Gas production and wind both lift the liner.

• Primary purposes:
  • Limit infiltration (leachate production)
  • Control gas emissions
• Typical Configuration
  • 
• Design based on:
  • Hydrologic principles to maximize runoff to limit infiltration
  • Geotechnical principles to prevent slope failures (see photo below)
    • If the drainage layer is not designed properly, pore pressure in the soil at the geomembrane surface will increase and the soil above the liner will slide down
  • Gas collection system requirements

Joining of Final Cover Membrane to Leachate Collection System Membrane

 

Failed Landfill Slope