Q & A's About Landfills

1. What exactly is a landfill?

A landfill is a specially designed facility for the burial of municipal solid waste. They are designed in such a way that leachates, cannot leak down through the soil into the water table. This is accomplished by a layer of clay-like soil at the bottom of the landfill. The next layer up is a synthetic lining, usually made of plastic. All remaining layers alternate between soil and garbage.

2. How much of our trash is disposed of in landfills?

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As of 1996, approximately 55% of all the United States' garbage resides in landfills, while 17% is incinerated, and 28% is recycled. The 28% that is recycled is greater than the EPA's initial goal of 25% recycling.

Source: US EPA, Office of Solid Waste

3. How does the trash in a landfill decompose?

There are three classes of bacteria and fungi that work to degrade garbage. Cellulolytic microbes initiate the process by breaking down the cellulose in paper, wood, and other plant wastes. Then acidogens ferment these sugars into acids, which methanogens then convert into methane gas and carbon dioxide.

4. What is "integrated" solid waste management?

This is an approach that includes a combination of waste prevention, waste reduction, and disposal techniques to effectively manage the problem of municipal solid waste. By reducing, reusing, recycling, and composting waste materials, less materials will appear in the waste stream destined for landfills or incinerators.

5. What is the problem with such terms as biodegradable and photodegradable?

Although green-advertising claims such as biodegradable and photodegradable sound good, they aren't always true. Plastics labeled biodegradable due to the addition of starch simply disintegrate into tiny non-degradable pieces after the starch has been degraded. Photodegradable plastics cannot be broken down in garbage cans or landfills because their degradation requires sunlight.

6. What types of materials are put in landfills?

Municipal solid waste landfills are filled with everything we throw away, from glass bottles to grass clippings and other yard wastes. The latter constitutes nearly 20% of all garbage landfilled. Disposable and non-durable products are major culprits in the growth of waste. In just one day, Americans throw away 150,000 tons of packaging material. This would fill 10,000 tractor trailer trucks, which would stretch 120 miles end to end. (Source: Garbage magazine)

7. What are the three main problems or environmental concerns associated with landfills?

Methane Gas, leachate, and loose waste are the three main challenges for landfills today. Methane gas is produced in a landfill by anaerobic decomposition. It can be collected using current technology and then used to generate electricity, or it can be purified and used as a power-generating fuel.

Leachate is a thick liquid that forms when garbage decomposes. At its best, it is similar to very strong sewage water; at its worst, it carries hazardous materials with it that were dissolved from the waste. Newer landfills have synthetic liners above a clay-like soil that help to prevent the leachate from leaking into the groundwater, causing contamination. Older landfills do not utilize this type of liner, and are therefore a threat to our groundwater especially to nearby neighborhoods.

Loose waste is another problem. It attracts disease carrying vermin of all types, and it can fly away in the breeze. At the end of every working day, a "daily cover" must be applied to minimize these problems. Once the landfill stops accepting waste, a final multi-layer cover must be applied to keep liquids away from the waste. Vegetation is then planted to reduce the effects of erosion.

8. What happens to landfills once they are closed?

After the landfill is closed, the degradation and settlement of the contents eventually reaches completion and stabilization. Upon stabilization, some landfill sites are used as parks, playgrounds, golf courses, or other facilities. Both John F. Kennedy and La Guardia Airports were built on landfills.

9. Are there products in my house that should not be sent to a landfill?

Many of the products we use in our homes are considered hazardous materials. A hazardous material is one that is toxic or will corrode metal, burn, or explode. Materials like oven cleaner, batteries, motor oil, paints, varnishes, thinners, fluorescent bulbs, mercury switches, etc., should not be sent to landfills because they are considered hazardous. These materials should be taken to a hazardous waste drop-off site. If every citizen convinces him or herself that "my hazardous materials are so small they won't matter," the total problem remains enormous.

10. What can be done to reduce the amount of trash in landfills?

Landfilling is a major component to integrated waste management. No matter what technologies are available, we can all help by reducing the amount of waste that we generate. This can be done in a variety of ways:

  • Strictly follow your community's recycling program.
  • Compost yard and organic wastes. Use them as nutrients for other plants.
  • Mulch leaves and grass clippings.
  • Buy recycled paper products and products with less packaging.
  • Buy durable products rather than disposable ones.
  • Reuse jars and containers.
  • Recycle oil and old tires.