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Landfills: How Do They Work?

Landfills across the world are unique in design and size but use similar methods and technologies. In this article, you will learn how they are built and work.

An active landfill still receives waste and packs it into open pits (landfill cells). A closed landfill has maxed out on space with non-active landfill cells and has been completely covered up. Typically, closed landfills are covered with soil and then grass or vegetation.

In the United States, a small landfill is classified as <52,000m³ in size, a medium landfill is 52,000-200,000m³, and a large landfill is >200,000m³.

Landfill formula

Image: How Landfills Work By: Craig Freudenrich, Ph.D. & Patrick J. Kiger

Despite their unique layouts, every landfill around the world follows a similar formula.

  1. Trash is collected and brought to landfills in dump trucks. The trucks are weighed and then directed to dump the garbage on top of an active landfill cell.
  2. Bulldozers smooth out the recently dumped trash. This step is twofold; smoothing the trash keeps active landfill cells even, and the weight of the bulldozers acts as a compactor, crushing trash into the tightest volume possible.
  3. Each day active landfill cells are covered with a layer of dirt to keep odor down and animals at bay.
  4. Once an active landfill is full, it is turned into a non-active landfill cell.

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Parts of an active landfill cell

Image: City Channel 4- Idaho City
  1. Daily cover of dirt. Covering the daily layer of waste with compacted soil seals the trash from the air and prevents pests from getting into the trash.
  2. Garbage. Each layer is a day worth of trash.
  3. Gas collection pipes. Gas collection pipes take the methane, carbon dioxide, nitrogen, and oxygen, produced from the breakdown of organic materials in landfill cells and release it.
  4. Drainage layer and pipes. The drainage layer and pipes collect water after rainfalls and channel it to drainage ditches surrounding the landfill's base. Once this water is tested for leachate and passes, it is allowed to flow offsite.
  5. Waterproof liner. The liner's main purpose is to contain trash in an area that does not touch the surrounding soil.
  6. Leachate collection pipes. Leachate pipes collect toxic water called leachate and carries it to a leachate collection pond.
  7. Clay, subsoil, and groundwater.

FAQs

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What is municipal solid waste (MSW)?

MSW is garbage! This waste is from everyday items discarded by everyday citizens. This includes household items, food waste, furniture, landscaping, clothes, etc.

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How big are landfills?

The average landfill is 600 acres, with the United State's biggest landfill (in Las Vegas) measuring a whopping 2,200 acres.

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Are landfills privately owned?

Landfills can be owned by private companies, governments, or even individuals.

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How many non-active landfills are there in the United States?

There are over 10,000 closed landfills in the U.S.

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