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What is a Landfill?
There are two ways to bury Solid Waste:
  • Dump - an open hole in the ground where trash is buried and that has various animals (rats, mice, birds) swarming around. (This is most people's idea of a landfill!)
  • Landfill - carefully designed structure built into or on top of the ground in which trash is isolated from the surrounding environment (groundwater, air, rain). This isolation is accomplished with a bottom liner and daily covering of soil.
    • Sanitary landfill - landfill that uses a clay liner to isolate the trash from the environment
    • Municipal solid waste (MSW) landfill - uses a synthetic (plastic) liner to isolate the trash from the environment


Trash is being loaded and compacted in a landfill.

The purpose of a landfill is to bury the trash in such a way that it will be isolated from groundwater, will be kept dry and will not be in contact with air. Under these conditions, trash will not decompose much. A landfill is not like a compost pile, where the purpose is to bury trash in such a way that it will decompose quickly.

First, it must be determined if there is sufficient land for the landfill. To give you an idea how much land is needed for a landfill, we'll use the example of the riverton city facility; (enter landfill dimensions here) The site takes up X amount acres of land, but only 70 acres is dedicated to the actual landfill. The remaining land is for the support areas (runoff collection ponds, leachate collection ponds, drop-off stations, areas for borrowing soil and 50- to 100-foot buffer areas).

Second, the composition of the underlying soil and bedrock must be determined. The rocks should be as watertight as possible to prevent any leakage from reaching groundwater. The bedrock must not be fractured or you cannot predict where wastes might flow. You would not want the site near mines or quarries because these structures frequently contact the groundwater supply. At the same time, you must be able to sink wells at various points around the site to monitor the groundwater or to capture any escaping wastes.

Third, the flow of water over the area must be studied. You do not want excess water from the landfill draining on to neighboring property or vice versa. Similarly, you do not want the landfill to be close to rivers, streams or wetlands so that any potential leakage from the landfill will not enter the groundwater or watershed.

Fourth, you need to determine the potential effects of the landfill and possible contamination on local wildlife. For example, you would not want to locate it near nesting areas of local or migrating birds. You would want to avoid local fisheries, too.

Finally, if the site contains any historical or archaeological artifacts, you would not want to build a landfill there.

 
Parts of a Landfill
 


 

This cross-section drawing shows the structure of a municipal solid waste landfill. The arrows indicate the flow of leachate.

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