The average layperson might have heard of landfills but most likely has never seen one and does not know how one works. These little-known facilities are part of the backbone of every functional city or any sizeable local community. Without them, most cities will become unhabitable pretty quickly and outbreaks of diseases will not be uncommon.

In this article, I will unpack everything you need to know about landfills, from their history to the process of decomposition and their impact on the environment.

What is a landfill and how does it work?

A landfill is a designated area where waste is disposed of by burying it underground. Landfills are the most common form of waste management in many countries, including the United States. They are designed to contain and manage waste in a way that minimizes the environmental impact.

The site is carefully designed to prevent the waste from contaminating the surrounding environment. The waste is typically covered with soil or other materials to prevent it from being exposed to the air.

The waste is then left to decompose over time. As the waste breaks down, it produces gases that are collected and used to generate energy. The remaining material is compacted to reduce its volume and covered with soil to prevent odours and the attraction of pests.

What is the Difference between a Landfill and a Dumpsite?

A landfill is different from a waste dump site. Landfills are engineered facilities that adhere to environmental standards, employ protection measures, have organized waste management practices, and are subject to monitoring and regulation.

In contrast, waste dumpsites are informal or unregulated sites with a lack of management controls, environmental pollution risks, absence of waste management practices, and limited monitoring and oversight. The main differences between the two are summarized in the table below.

Landfill Waste Dumpsite
Engineered and constructed facilities Informal or unregulated sites
Adhere to environmental standards Lack proper management controls
Employ environmental protection measures High risk of environmental pollution
Organized waste management practices Lack of waste management practices
Subject to monitoring and regulation Lack monitoring and oversight
Long-term waste disposal Temporary and unplanned solution


History of Landfills

Landfills, or more accurately, waste dumpsites have been used for thousands of years, dating back to ancient Greece and Rome.

Landfills have a long history, with early societies disposing of waste in designated areas. In the 19th century, sanitary landfills emerged to contain waste with basic controls. However, modern landfills did not emerge until the late 1800s.  In the mid-20th century, regulations and advancements improved landfill practices, including liners and gas collection systems.

One of the first modern landfill was built in Fresno, California, in 1937. Modern landfills use advanced technologies to minimize pollution, focusing on waste reduction and recycling. Efforts are underway to explore innovative solutions and transition to sustainable waste management systems.


What goes into a landfill?

Landfills accept a wide range of waste, including household trash, yard waste, and construction debris.  Waste that are of hazardous nature like chemicals or medical waste have specialized landfills where such waste or residues from their treatment are disposed. The design of these types of landfills would include features to protect surrounding sub-soil from the harmful nature of waste disposal. Such features would include the use of geomembranes to protect the soil below the waste.


What do landfills do with trash?

Once the waste is collected and transported to a landfill, it is sorted and separated to remove any hazardous materials. The remaining waste is then compacted to reduce its volume. The compacted waste is covered with soil or other materials to prevent odours and the attraction of pests. The steps involved in waste disposal at the landfill are detailed below:

  1. Waste Reception and Inspection: Upon arrival, the waste is inspected to ensure compliance with landfill regulations, and any prohibited or hazardous materials are identified and segregated.
  2. Weighing and Documentation: The waste is weighed, and relevant documentation, including waste manifests, is completed for record-keeping and regulatory purposes.
  3. Waste Placement: The waste is then placed in designated areas or waste disposal cells within the landfill. The cells are carefully planned to optimize space utilization and waste compaction.
  4. Waste Compaction: Heavy machinery, such as compactors or bulldozers, is used to compress and compact the waste within the disposal cells. Compaction reduces the volume of waste and increases the landfill’s capacity.
  5. Daily Covering: At the end of each operational day or as required by regulations, a layer of cover material (usually soil or alternative approved materials) is placed over the newly deposited waste. Daily covering helps control odours, vectors, and dust, and also provides a barrier against rainwater infiltration.
  6. Methane and Leachate Management: Landfills produce methane gas and leachate (liquid that percolates through the waste). Methane gas is collected using a system of pipes and vents for proper management, often for energy generation. Leachate is captured and treated to prevent contamination of surrounding groundwater.
  7. Monitoring and Compliance: Landfills are subject to regular monitoring to ensure compliance with environmental regulations. Monitoring parameters may include groundwater quality, gas emissions, leachate collection, and landfill stability.
  8. Final Closure and Post-Closure Care: When a landfill reaches its capacity or planned lifespan, it undergoes closure procedures, including capping the waste with a final cover system. Post-closure care involves ongoing monitoring and maintenance to ensure environmental protection and compliance even after the landfill is no longer operational.



Landfill Gas and Leachate

The gases produced by the decomposition of waste in landfills are primarily methane and carbon dioxide. These gases are collected and used to generate electricity or heat. Landfills also produce a liquid called leachate, which is formed when rainwater passes through the waste and becomes contaminated. Leachate is collected and treated to prevent it from contaminating the environment. Leachate can be processed and disposed of in sewer lines it can be recycled and used for purposes like irrigation.


How long does it take for a landfill to decompose?

The decomposition of waste in a landfill can take many years, depending on the type of waste and the conditions in the landfill. Organic materials, such as food waste and yard waste, decompose more quickly than other materials, such as plastics and metals.

Some materials, such as glass and aluminium, do not decompose at all. These materials remain in the landfill indefinitely unless they are removed and recycled. This is why it is crucial is segregate these types of materials and recycle them before they end up in the landfill.


How are landfills built?

Landfills are carefully designed and constructed to minimize their impact on the environment. The site is chosen based on factors such as soil type, groundwater levels, and proximity to residential areas.

The landfill is then built in layers, with each layer consisting of a liner, a drainage system, and a layer of compacted waste. The landfill is capped with a layer of soil or other materials to prevent the release of gases and odours.


Geomembrane Layer in Landfill

After the landfill is full

Once a landfill is full, it is closed and carefully monitored to ensure that it does not pose a threat to the environment. The site is covered with a final cap, which is designed to prevent the release of gases and liquids.

The landfill is then monitored for many years to ensure that it remains stable and does not pose a threat to the environment. The site of the landfill can be covered in green fields and used for recreational purposes or to serve other purposes. A good example is Dubai Safari Park, a zoo and wildlife sanctuary built over a former landfill site.

Landfill regulations and environmental impact

Landfills are highly regulated to minimize their impact on the environment. Regulations cover everything from the design and construction of the landfill to the types of waste that can be accepted.

Despite these regulations, landfills still have a significant impact on the environment. Landfills produce greenhouse gases, such as methane, which contribute to climate change. They also pose a threat to groundwater and surface water quality.

Landfill alternatives

There are several alternatives to landfills for waste management. These include recycling, composting, Incinerators and waste-to-energy facilities. These alternatives can help to reduce the amount of waste that is sent to landfills and minimize their impact on the environment.


Landfills are an important part of our waste management system, but they also have a significant impact on the environment. Understanding how landfills work can help us to make more informed decisions about waste management and reduce our impact on the environment.

As individuals, we can help to reduce the amount of waste we produce by recycling, composting, and reducing our consumption of single-use products. By working together, we can create a more sustainable future for ourselves and future generations.

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