Types of Landfills

Landfills, specialized facilities for the management of waste, are among the most common strategies for dealing with wastes. Modern, secure landfills are depressions in the ground or above-ground facilities that are filled with waste and sealed to avoid contact with surrounding soil, air or water. In fact, the main objective of landfill construction is to concentrate waste and isolate it from other resources that could be adversely affected by contact with the dangerous chemicals contained in some wastes. In order to achieve this purpose, a number of different types of landfills and disposal facilities exist.

Municipal Solid Waste Landfills (MSWLFs)

• MSWLFs receive all kinds of household solid wastes, like nonrecyclable paper, plastic and household goods, as well as some nonhazardous wastes like construction debris and sludge. MSWLFs are usually surrounded by plastic, clay or composite layers that keep the wastes from coming into contact with the surrounding environment and are either located underground or in above-ground containers that resemble stadiums. The enclosure is filled with waste and later sealed to completely isolate the contents from surrounding soils, air or subterranean and surface water resources.

Hazardous Waste Landfills

• Wastes that contain elements that can be hazardous to the environment or human health, such as paints, batteries or toxic industrial wastes, are directed to certified hazardous waste landfills. These landfills are similar to MSWLFs, but have additional protective layers and safety procedures to keep contaminants out of the environment and often have more stringent regulations governing the location, composite liner requirements, collection and removal systems, closure and postclosure care requirements, operating practices and environmental monitoring procedures of the facilities.

Injection Wells

• Injection wells are often used for the disposal of liquid wastes. As the name suggests, they are wells dug deep into the earth and filled with liquid wastes through an injection process. As liquid wastes can be as toxic as solid wastes and are often more difficult to contain, injection wells feature very extensive safety protocols and liner requirements, keeping potentially dangerous liquid wastes out of subterranean water resources and soils.

Methane-Trapping Landfills

• The decomposition of organic matter often produces methane as a byproduct. Methane is a dangerous heat-trapping gas and a contributor to global warming, but also a usable gas that can be combusted as fuel or cooking oil. Therefore, several landfills are equipped with machinery to trap methane from the decomposition of wastes and store the resource for later use, keeping a greenhouse gas out of the atmosphere and turning a waste product into a usable resource.