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Landfill Design and Operations Flashcards

7 cards from real CPWM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Landfill Design and Operations flashcards as text

  1. What is the primary purpose of a leachate collection and removal system (LCRS) in a municipal solid waste landfill?

    Answer: To collect and remove contaminated liquid that percolates through waste

    An LCRS collects leachate—liquid that has percolated through waste and picked up contaminants—and removes it to prevent liner breaches and groundwater contamination.

  2. Under RCRA Subtitle D, what minimum slope is typically required for the bottom liner of a municipal solid waste landfill to ensure proper leachate drainage?

    Answer: 2%

    Subtitle D regulations require a minimum 2% bottom slope to ensure leachate drains toward collection pipes rather than pooling on the liner.

  3. Which type of soil is most commonly specified as a component of composite liner systems because of its low hydraulic conductivity?

    Answer: Compacted clay

    Compacted clay with hydraulic conductivity ≤1×10⁻⁷ cm/s is specified under RCRA regulations as the soil component of composite liner systems.

  4. What is the function of a geomembrane in a landfill liner system?

    Answer: To act as a primary barrier preventing leachate migration

    A geomembrane (typically HDPE) serves as a flexible, near-impermeable barrier that prevents leachate from migrating into native soil and groundwater.

  5. Daily cover is required at active landfills primarily to:

    Answer: Control odors, vectors, and fire, and reduce litter

    Daily cover—typically 6 inches of soil or approved alternative—controls odors, vectors (rodents, birds), blowing litter, and fire hazards.

  6. A landfill operator notices that the leachate collection pipes are draining more slowly than usual. What is the most likely cause?

    Answer: Biological clogging or sedimentation in the drainage layer

    Biological clogging (biofouling) and sedimentation of fine particles in the granular drainage layer are the most common causes of reduced LCRS flow rates.

  7. Which landfill operational practice helps maximize the airspace utilization and structural stability of the waste mass?

    Answer: Compacting waste in 2-foot lifts using a landfill compactor

    Compacting waste in 2-foot (approximately 0.6 m) lifts with a landfill compactor maximizes density, conserves airspace, and improves slope stability.