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A landfill in Poland
A landfill in Perth, Western Australia


A landfill, also known as a dump or rubbish dump (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 organised waste disposal and remain so in many places around the world.

Landfills may include internal waste disposal sites (where a producer of waste carries out their own waste disposal at the place of production) as well as sites used by many producers. Many landfills are also used for other 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 soil and 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.

Site construction requirements

The construction of a landfill requires a staged approach. Landfill designers are primarily concerned with the viability of a site. To be commercially and environmentally viable a landfill must be constructed in accord with specific requirements, which are related to:

  • Location
    • Easy access to transport by road
    • Transfer stations if rail network is preferred
    • Land value (price)
    • Cost of meeting government requirements
    • Location of community served
    • Type of construction (more than one may be used at single site)
      • Pit - filling existing holes in the ground, typically left behind by mining
      • Canyon - filling in naturally occurring valleys or canyons
      • Mound - piling the waste up above the ground
  • Stability
    • Underlying geology
    • Nearby earthquake faults
    • Water table
    • Location of nearby rivers, streams, and flood plains
  • Capacity The available void space must be calculated by comparison of the landform with a proposed restoration profile.
    • This calculation of capacity is based on:
    • Density of the wastes
    • Amount of intermediate and daily cover
    • Amount of settlement that the waste will undergo following tipping
    • Thickness of capping
    • Construction of lining and drainage layers.






  • Costs
    • Feasibility studies
    • Site after care
    • Site investigations (costs involved may make small sites uneconomical).
    • Site respect


Operations

Typically, in non hazardous waste landfills, in order to meet predefined specifications, techniques are applied by which the wastes are:
  1. Confined to as small an area as possible.
  2. Compacted to reduce their volume.
  3. 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. Afterwards, the waste collection vehicles use the existing road network on their way to the tipping face or working front where they unload their load. After loads are deposited, compactors or dozers are used to spread and compact the waste on the working face. Before leaving the landfill boundaries, the waste collection vehicles pass through the 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. 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 daily. Alternative waste-cover materials are several sprayed-on foam products and temporary blankets. Blankets can be lifted into place with tracked excavators and then removed the following day prior to waste placement. Chipped wood and chemically 'fixed' bio-solids, may also be used as an alternate daily cover. 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.

Land reclamation

As human overcrowding of developed areas intensified during the 20th century, it has become important to develop land re-use strategies for completed landfills. Some of the most common usages are for parks, golf courses and other sports fields. Increasingly, however, office buildings and industrial uses are made on a completed landfill. In these latter uses, methane capture is customarily carried out to minimize explosive hazard within the building.

An example of a Class A office building constructed over a landfill is the Dakin Buildingmarker at Sierra Point, Brisbane, Californiamarker. The underlying fill was deposited from 1965 to 1985, mostly consisting of construction debris from San Franciscomarker and some municipal wastes. Aerial photographs prior to 1965 show this area to be tideland of the San Francisco Bay. A clay cap was constructed over the debris prior to building approval.

A notable example is Sydney Olympic Parkmarker, the primary venue for the 2000 Summer Olympic Games, which was built atop an industrial wasteland that included landfills.

Another strategy for landfill reclamation is the incineration of landfill trash at high temperature via the plasma-arc gasification process, which is currently used at two facilities in Japanmarker, and will be used at a planned facility in St. Lucie Countymarker, Floridamarker.

Impacts

A large number of adverse impacts occur from landfill operations. These impacts can vary: fatal accidents (e.g., scavengers buried under waste piles); infrastructure damage (e.g., damage to access roads by heavy vehicles); pollution of the local environment (such as contamination of groundwater and/or aquifers by leakage and residual soil contamination during landfill usage, as well as after landfill closure); offgassing 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); harbouring of disease vector such as rats and flies, particularly from improperly operated landfills, which are common in Third-world countries; injuries to wildlife; and simple nuisance problems (e.g., dust, odour, vermin, or noise pollution).

Environmental noise and dust are generated from vehicles accessing a landfill as well as from working face operations. These impacts are best to intercept at the planning stage where access routes and landfill geometrics can be used to mitigate such issues. Vector control is also important, but can be managed reasonably well with the daily cover protocols.

Most modern landfills in industrialized countries are operated with controls to attempt manage problems such as these. Analyses of common landfill operational problems are available.

Some local authorities have found it difficult to locate new landfills. Communities may charge a fee or levy in order to discourage waste and/or recover the costs of site operations. Some landfills are operated for profit as commercial businesses. Many landfills, however, are publicly operated and funded.

Trash dump communities

In many developing countries around the world, communities exist in and around landfills. Residents of these communities, such as La Chureca in Nicaraguamarker, often live in conditions of extreme poverty and use the landfills as a source of food and income. Scavengers work in the garbage in search of recyclables and other valuables.

Landfill gas

Gasses are produced in landfills due to the anaerobic digestion by microbes on any organic matter. This gas can be collected and flared off or used to generate electricity in a gas fired power plant. Landfill gas monitoring can be carried out to alert for the the presence of a build-up of gasses to a harmful level.

Regional practice

European Union

European Landfill Directive

New Zealand

United Kingdom

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 landfilled. In addition to this the Landfill Allowance Trading Scheme has been established for local authorities to trade landfill quotas.

United States

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); such as was the case with the Fresh Kills Landfillmarker in Staten Islandmarker, which is claimed by many to not only be the world's largest landfill, but the world's largest human structure. The landfill has since been closed and is being transformed into a park.

Reclaiming materials

Waste-fired power plants with material recovery can be useful in cleaning up landfills
Landfills can be regarded as a viable and abundant source of source 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 Fossil-fuel_power_plant and waste incinerators which have build-in material recovery. This material recovery is possible trough the use of filters (electro filter, active carbon and potassium filter, quench, HCL-washer, SO2-washer, bottom ash-grating, ...) 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 coppermine, the waste fired plant could recover more copper.

Alternatives

The obvious 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. Anaerobic digestion, composting, mechanical biological treatment, pyrolysis and plasma arc gasification have all began to establish themselves in the market.

In recent years, some countries, such as Germanymarker, Austriamarker, Belgiummarker, and Switzerlandmarker, 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.

See also



References

Further reading



External links




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