How Landfills Work

By: Craig Freudenrich, Ph.D.

Proposing the Landfill

For a landfill to be built, the operators have to make sure that they follow certain steps. In most parts of the world, there are regulations that govern where a landfill can be placed and how it can operate. The whole process begins with someone proposing the landfill.

In the United States, taking care of trash and building landfills are local government responsibilities. Before a city or other authority can build a landfill, an environmental impact study must be done on the proposed site to determine:


  • the area of land necessary for the landfill
  • the composition of the underlying soil and bedrock
  • the flow of surface water over the site
  • the impact of the proposed landfill on the local environment and wildlife
  • the historical or archaeological value of the proposed site

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 a site we visited, the North Wake County Landfill in Raleigh, North Carolina. This site has both a sanitary landfill, which was closed in 1997, and a working MSW landfill. The site takes up 230 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.

Once the environmental impact study has been completed, permits must be obtained from the local, state and federal governments. In addition, money will have to be raised from taxes or municipal bonds to build and operate the landfill. The North Wake County Landfill cost about $19 million to build and was paid for through municipal bonds. Because funding usually comes from some public source, public approval must be obtained through local governments or a referendum.