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Environmental Education

Landfill Science
Despite everyone's best efforts to reduce, reuse and recycle, we will always need safe disposal options for some materials. It is our job to make sure that it is done in an environmentally sound manner. That’s where landfill science comes in.

Today’s landfills are highly-engineered systems with many layers of environmental protection. The following are descriptions of the complex environmental systems that make up a landfill:
  • Liner System
    Modern day landfills are designed and constructed with environmental protection systems. A liner system creates an impenetrable barrier between soil and groundwater and what goes into the landfill. A typical liner starts with a composite liner of clay and synthetic material. Clay is compacted to increase impermeability (meaning that liquids can’t get through). A high-density plastic liner is placed over the clay and a drainage layer is installed over the liner. The liner system must meet all state and federal regulations.
  • Drainage and Liquids Management
    The environmental protection measures used at a landfill also include a system to collect leachate—liquids from inside the landfill. A perforated pipe is placed on top of the liner system to allow for proper drainage and collection of rainwater and other liquids. Collected liquid is responsibly treated onsite or at a wastewater treatment plant.
  • Landfill Gas
    As waste decomposes, a gas byproduct is naturally produced. These gases consist primarily of carbon dioxide and methane, which is the primary component of natural gas. Carbon dioxide, soluble in water, is most likely to leave the landfill with liquids. Methane, however, is less soluble in water and lighter than air, and exists as a gas. The gas is captured using gas-collection wells. The landfill gas is burned and, in some cases, used as a renewable energy source.

    Republic Services operates approximately 69 landfill gas-to-energy projects nationwide, generating enough energy to meet the electricity or heating needs of more than 360,000 homes.
  • Rainfall
    Storm water runoff is collected and contained in sedimentation basins. These ponds allow soil particles to settle out of the water before it is discharged to a nearby waterway.
  • Groundwater Monitoring
    Groundwater is one of the most important concerns at a landfill. Monitoring wells are installed and checked regularly.
  • Working Face
    This main part of the landfill is where trash is placed by trucks and then compacted by heavy machines. Each day, the new garbage is covered with dirt, or another approved cover layer, to contain odors and discourage pests.
  • Final Cap
    When a landfill section is full to capacity, it is capped with a final cover and monitored for at least 30 years. A typical cap consists of a synthetic plastic liner that is placed on top, entombing all that was put into the landfill. The liner is then topped with approximately 24 inches of soil and final vegetation.
  • Solar Landfill Cover
    Republic Services has pioneered a solar energy technology that allows landfills to increase their overall energy output. The innovative solar landfill cover is an integrated geomembrane and photovoltaic solar panel system. The cover has been applied at select landfills to produce renewable energy resulting in a solution that is flexible, aesthetically pleasing, efficient and economical.
Today, Republic Services operates nearly 200 landfills across the United States. Our commitment to the planet includes continued innovation in environmental engineering.

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