Waste management
Glossary
open dump – an open area where people leave trash
surface impoundment – a low area, such as a hole, that holds liquid waste
deep-well disposal – a method of disposing of liquid waste by injecting it into deep underground rock
composite liner – is a piece of synthetic material that is placed over the soil that has been pressed down
disposal capacity – the largest amount of waste that an area can hold
methane recovery – the collection of the gas methane in order to use it for other purposes, such as generating electricity
carbon storage – the capture and storage of CO2 so that it is not released into the atmosphere
Applied methods
The two commonly used methods of dealing with solid waste are incineration and sanitary landfills.

Incineration is a relatively efficient operation, but requires a large capital investment 
with continued high operation expenditures.

At present the most workable method is sanitary landfill. 

Municipal solid wastes are compressed at landfill area. They should be compressed until the optimum density. 

The aim of the compression is 
1-	to reduce the volume of waste
2-	to have a stiff layer of waste for safety
3-	additional cells (layers) can be constructed above it.

At the landfill all the solid wastes received are spread and compressed in layers.  At the end of each working day, or more frequently, it is covered completely with soil and also compacted. The compacted waste and soil cover constitute a cell. 

A series of adjoining cells, all of the same height, makes up a lift. The completed landfill consists of one or more lifts. 

Waste Cells and Lifts
Each day's deposit of covered waste is called a cell. A continuous row of cells is called a lift. The landfill is made up of many lifts.
Trash is compacted into areas, called cells, that contain only one day's trash. In the North Wake County Landfill, a cell is approximately 50 feet long by 50 feet wide by 14 feet high (15.25m x 15.25m x 4.26m). The amount of trash within the cell is 2,500 tons and is compressed at 1,500 pounds per cubic yard! This compression is done by heavy equipment (tractors, bulldozers, rollers and graders) that go over the mound of trash several times). 
Daily Cover
At the end of each day's operation, bulldozers spread and compact at least 6 inches of earth over all of the waste. The daily cover prevents the emergence of flies and other insects, and controls odors, blowing litter and the infiltration of rainfall.
Methane Collection System
Bacteria in the landfill break down the trash in the absence of oxygen (anaerobic) because the landfill is airtight. A by-product of this anaerobic breakdown is landfill gas, which contains approximately 50 percent methane and 50 percent carbon dioxide with small amounts of nitrogen and oxygen. This presents a hazard because the methane can explode and/or burn. So, the landfill gas must be removed. To do this, a series of pipes are embedded within the landfill to collect the gas. In some landfills, this gas is vented or burned.
 More recently, it has been recognized that this landfill gas represents a usable energy source. The methane can be extracted from the gas and used as fuel.