A landfill site (also known as a tip, dump, rubbish dump or dumping ground and historically as a midden) is a site for the disposal of waste materials by burial and is the oldest form of waste treatment. Historically, landfills have been the most common methods of organized waste disposal and remain so in many places around the world. Some landfills are also used for waste management purposes, such as the temporary storage, consolidation and transfer, or processing of waste material (sorting, treatment, or recycling).
A landfill also may refer to ground that has been filled in with rocks instead of waste materials, so that it can be used for a specific purpose, such as for building houses. Unless they are stabilized, these areas may experience severe shaking or liquefaction of the ground in a large earthquake.
Typically, in non hazardous waste landfills, in order to meet predefined specifications, techniques are applied by which the wastes are:
- Confined to as small an area as possible.
- Compacted to reduce their volume.
- Covered (usually daily) with layers of soil.
During landfill operations the waste collection vehicles are weighed at a weighbridge on arrival and their load is inspected for wastes that do not accord with the landfill’s waste acceptance criteria. Afterward, the waste collection vehicles use the existing road network on their way to the tipping face or working front where they unload their contents. After loads are deposited, compactors or bulldozers are used to spread and compact the waste on the working face. Before leaving the landfill boundaries, the waste collection vehicles pass through a wheel cleaning facility. If necessary, they return to the weighbridge in order to be weighed without their load. Through the weighing process, the daily incoming waste tonnage can be calculated and listed in databases for record keeping. In addition to trucks, some landfills may be equipped to handle railroad containers. The use of 'rail-haul' permits landfills to be located at more remote sites, without the problems associated with many truck trips.
Typically, in the working face, the compacted waste is covered with soil or alternative materials daily. Alternative waste-cover materials are chipped wood or other "green waste", several sprayed-on foam products, chemically 'fixed' bio-solids and temporary blankets. Blankets can be lifted into place at night then removed the following day prior to waste placement. The space that is occupied daily by the compacted waste and the cover material is called a daily cell. Waste compaction is critical to extending the life of the landfill. Factors such as waste compressibility, waste layer thickness and the number of passes of the compactor over the waste affect the waste densities.
Many adverse impacts may occur from landfill operations. Damage can include infrastructure disruption (e.g. damage to access roads by heavy vehicles); pollution of the local environment (such as contamination of groundwater and/or aquifers by leakage or sinkholes and residual soil contamination during landfill usage, as well as after landfill closure); off gassing of methane generated by decaying organic wastes (methane is a greenhouse gas many times more potent than carbon dioxide, and can itself be a danger to inhabitants of an area); harboring of disease vectors such as rats and flies, particularly from improperly operated landfills, which are common in developing countries; injuries to wildlife; and simple nuisance problems (e.g., dust, odor, vermin, or noise pollution).
Though offsite impacts of landfills are of primary concern to regulators, the status of the resident microbial community in a landfill may determine the efficiency with which natural attenuation of contaminants proceeds on site. For example, Gomez et al. (2011) showed that bacterial diversity, including diversity of pollutant degraders was variable within a major landfill site in Medellin, Columbia and was related to the level of contamination within a particular zone.
Some local authorities have found it difficult to locate new landfills. Communities may charge a fee or levy to discourage waste and/or recover the costs of site operations. Many landfills are publicly funded, but some are commercial businesses, operated for profit.
One of the problems of landfills is pollution of the road from dirty wheels on vehicles when they leave the landfill. To reduce this, wheel washing systems are used to clean the wheels as the vehicle exits the landfill. Poisonous leachate can also leak from the landfill contaminating nearby soil and groundwater. Methane gases are flammable and explosive if exposed to heat.
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Landfills in Canada are regulated by provincial environmental agencies and environmental protection acts (EPA). Older dumps tend to fall under current standards and are monitored for leaching. Some former dumps have been converted to parkland and close to residential developments.
In countries of the European Union, individual states are obliged to enact legislation to comply with the requirements and obligations of the European Landfill Directive. In the UK this is the Waste Implementation Programme.
Trash and garbage is a common sight in urban and rural areas of India. It is a major source of pollution. Indian cities alone generate more than 100 million tons of solid waste a year. Street corners are piled with trash. Public places and sidewalks are despoiled with filth and litter, rivers and canals act as garbage dumps. In part, India's garbage crisis is from rising consumption. India's waste problem also points to a stunning failure of governance.
In 2000, India's Supreme Court directed all Indian cities to implement a comprehensive waste-management program that would include household collection of segregated waste, recycling and composting. The Organization for Economic Cooperation and Development estimates that up to 40 percent of municipal waste in India remains simply uncollected.
In 2011, several Indian cities embarked on waste-to-energy projects of the type in use in Germany, Switzerland and Japan. For example, New Delhi is implementing two incinerator projects aimed at turning the city’s trash problem into electricity resource. These plants are being welcomed for addressing the city’s chronic problems of excess untreated waste and a shortage of electric power. They are also being welcomed by those who seek to prevent water pollution, hygiene problems, and eliminate rotting trash that produces potent greenhouse gas methane. The projects are being opposed by waste collection workers and local unions who fear changing technology may deprive them of their livelihood and way of life. And A2Z Group, Website headquartered in Gurgaon, Delhi has set up Integrated Resource Recovery Facilities with an aggregate MSW capacity of 3,800 tons per day (“TPD”) in six cities, along with the collection and transportation (“C&T”) of MSW of an aggregate capacity of 910 TPD in two cities. They also have the processing and disposal (“P&D”) of MSW of an aggregate capacity of 488 TPD in six cities in India.
Landfilling practices in the UK have had to change in recent years to meet the challenges of the European Landfill Directive. The UK now imposes landfill tax upon biodegradable waste which is put into landfills. In addition to this the Landfill Allowance Trading Scheme has been established for local authorities to trade landfill quotas in England. A different system operates in Wales where authorities are not able to 'trade' between themselves, but have allowances known as the Landfill Allowance Scheme.
In the U.S., landfills are regulated by the state's environmental agency that establishes minimum guidelines; however, none of these standards may fall below those set by the United States Environmental Protection Agency (EPA).
Bacteria have been found in landfills that digest plastic. 
Landfills can be regarded as a viable and abundant source of materials and energy. In the developing world, this is widely understood and one may thus often find waste pickers scavenging for still usable materials. In a commercial context, landfills sites have also been discovered by companies and many have begun harvesting materials and energy . Well known examples are gas recovery facilities. Other commercial facilities include waste incinerators which have built-in material recovery. This material recovery is possible through the use of filters (electro filter, active carbon and potassium filter, quench, HCL-washer, SO2-washer, bottom ash-grating, etc.). An example of these is the AEB Waste Fired Power Plant. The AEB waste incinerator is hereby able to recover a large part of the burned waste in source materials. According to Marcel van Berlo (who helped build the plant), the processed waste contained higher percentages of source materials than any mine in the world. He also added that when the plant was compared to a Chilean copper mine, the waste fired plant could recover more copper. However, because of the high concentration of gases and the unpredictability of the landfill contents, which often include sharp objects, landfill excavation is generally considered dangerous. Furthermore, the quality of materials residing within landfills tends to degrade and such materials are thought to be not worth the risks required to recover them.
The alternatives to landfills are waste reduction and recycling strategies. Secondary to not creating waste, there are various alternatives to landfills. In the late 20th century, alternative methods of waste disposal to landfill and incineration have begun to gain acceptance. Waste-to-energy incineration, anaerobic digestion, composting, mechanical biological treatment, pyrolysis and plasma arc gasification have all begun to establish themselves in the market.
In recent years, some countries, such as Germany, Austria, Sweden, Denmark, Belgium, the Netherlands, and Switzerland, have banned the disposal of untreated waste in landfills. In these countries, only the ashes from incineration or the stabilized output of mechanical biological treatment plants may still be deposited.
- Bioreactor landfill
- Daily cover
- Hydrologic Evaluation of Landfill Performance or HELP modfu
- Landfill diversion
- Land reclamation
- Landfill tax
- List of solid waste treatment technologies
- Marine debris
- Mechanical biological treatment
- Solid Waste Association of North America
- Waste management
- "Alternative Daily Cover (ADC)". Retrieved September 14, 2012.
- "Five years on, east Pasco landfill proposal still in dispute". Tampa Tribune. July 8, 2011. Retrieved 2011-07-13.
- Gomez, A.M.; =Yannarell, A.C.; Sims, G.K.; Cadavid-Resterpoa, G.; Herrera, C.X.M. (2011). "Characterization of bacterial diversity at different depths in the Moravia Hill Landfill site at Medellín, Colombia". Soil Biology and Biochemistry 43 (6): 1275–1284. doi:10.1016/j.soilbio.2011.02.018.
- "Drowning in a Sea of Garbage". The New York Times. April 22, 2010.
- "What is waste to energy?". Confederation of European Waste-to-Energy Plants. 2010.
- "Indian waste workers fear loss of income from trash-to-electricity projects". The Washington Post. November 20, 2011.
- Gwyneth Dickey Zaikab (March 2011). "Marine microbes digest plastic".
- Multiple Purpose industries using landfills for energy
- Commercial exploitation of gas from landfills
- AEB Waste Fired Power Plant
- Waste fired power plant by AEB recovers materials
- Kijk magazine, April 2008
- "Council Directive 1999/31/EC of 26 April 1999, on the landfill of waste" (PDF). Retrieved August 29, 2005.
- "The Landfill Operation Management Advisor Web Based Expert System". Retrieved August 29, 2005.
- H. Lanier Hickman Jr. and Richard W. Eldredge. "Part 3: The Sanitary Landfill". A Brief History of Solid Waste Management in the US During the Last 50 Years. Retrieved August 29, 2005.
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