Landfill
For other uses see: Landfill (disambiguation). |
A landfill compaction vehicle in operation |
A
landfill, also known as a
dump (US) or a
tip (UK), is a site for the disposal of
waste materials by burial and is the oldest form of
waste treatment. Historically, landfills have been one of the most common methods of organized
waste management (along with
incineration), 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 definition of landfill in the
EU, as well as regulations for the landfilling of waste, may be found at [
1].
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.
Most modern landfills are classified according to the type(s) of waste material disposed of into them. Landfills can be engineered to a high standard in order to contain liquid
leachate or
landfill gas produced by decomposing organic waste. Modern landfills generally require a minimum of one
containment liner, consisting of a layer of compacted
clay with a minimum thickness and maximum
hydraulic conductivity. Others also require the addition of one or more layers of
impermeable membrane, such as
high-density polyethylene (HDPE). Various final cover systems are used to 'cap' landfills (such as clay or
topsoil), depending on the type of wastes present within the landfill.
Landfills, based on the waste type that is disposed within them, may be classified as: #
Hazardous waste landfill: waste disposal units constructed to specific design criteria and which receive wastes meeting the local definition of hazardous waste. These landfills are generally constructed to be secure repositories for material that presents a serious hazard to
human health, such as high-level
radioactive waste.#
Sanitary landfills: also called
modern,
engineered or
secure landfills, these usually have physical barriers such as
liners and
leachate collection systems, and procedures to protect the
public from exposure to the disposed wastes. The term sanitary landfill normally refers to those where
municipal solid waste is disposed of, as well as other wastes high in organic material. In some countries, all landfills are sanitary landfills. #
Inert Waste landfill: waste disposal units that receive wastes which are chemically and physically stable and do not undergo decomposition, such as
sand,
bricks,
concrete or
gravel.#
Dumps: also simply called landfills, dumps are landfills that are not engineered with the special protective measures required by sanitary landfills. They are most common in
rural, remote, and developing areas. Many jurisdictions prohibit the use of non-sanitary landfills for the disposal of
municipal solid waste. Other jurisdictions that do allow dumps may require them to be constructed according to some engineering standard to mitigate the risk for
environmental contamination, such as by limiting the slope, requiring
compaction, or ensuring that the cell is high enough above the
groundwater table.
Landfill subsystems
A typical landfill consists of subsystems such as the:
*
Bottom liner system
*
Leachate collection and management system.
*
Landfill gas management system
*
Monitoring system for landfill gas & leachate
*
Road network
*
Drainage system *Final
capping system Their function is to secure the normal landfill operations and to control the anticipated
emissions generated mainly by the
decomposition of
organic matter, such as
leachate and
landfill gas.
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 railnetwork is preferred
**Land value
**Cost of meeting government requirements, such as the
Environment Agency in England and Wales:required to consider location of community served
*
Stability**Underlying geology
**Water table
**Location of nearby rivers and streams
*
Capacity**cost of feasiability studies, site after care, site investigations (costs involved make small sites uneconomic)
Capacity is a crucial element of landfill design. The available
voidspace must be calculated by comparison of the landform with a proposed restoration profile.
This calulation 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.
*
Protection of soil and water through:
**Installation of liner and collection systems.
**
Storm water control**
Leachate management.
**
Landfill gas management.
*
Nuisances and hazards management.Typically, in non hazardous waste landfills, a
technique is applied by which the wastes are: #Confined to an as small area as possible. #Compacted to reduce their volume. #Covered (usually daily) with layers of soil, in order to meet predefined
specifications.
|
Landfill operation. Note that the area being filled is a single, well-defined "cell" and that a rubberized liner is in place (exposed on the left) to prevent contamination by leachates migrating downward through the underlying geological formation. |
Description of landfill operations
During landfill operations the waste collection vehicles or
garbage trucks are weighed at a weigh-bridge 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 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.
Typically, in the working face, the compacted waste is covered with soil daily. Alternative waste cover materials are several
foam products and temporary blankets. Foams must be sprayed on. Blankets can be lifted into place with tracked
excavators and 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 daily cell. Waste compaction is critical to extending the landfill's life. Factors such as waste
compressibility, waste layer thickness and the number of passes of the
compactor over the waste affect the waste
densities.
A number of problems can 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
leachate and residual
soil contamination after landfill closure), to simple nuisance problems (e.g., dust, odour,
vermin, or
noise pollution).
Most modern landfills are operated with controls to manage problems such as these.
Analysis and
advice on common landfill operational problems are available in [
2].
Social issues
Some local authorities have found it difficult to locate new landfills. These authorities 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. For many areas, a well-run landfill is a hygienic, inexpensive solution to garbage disposal.
In the U.S., landfills are regulated by the state's environmental agency that establishes minimum guidelines; though no guideline may fall below that of the U.S.
EPA.
The "Fresno Municipal Sanitary Landfill", opened in
Fresno,
California in
1937, is considered to have been the first modern, sanitary landfill in the
United States, innovating the techniques of trenching, compacting, and the daily covering of trash with dirt. It has been designated a
National Historic Landmark, underlining the significance of waste disposal in urban society.
Before the advent of modern landfills in America, most Americans lived in sparsely populated rural farming communities and most incinerated their garbage. Due to environmental and safety concerns, burning garbage by civilians has been outlawed by most municipalities and can only be performed by landfill managers or people who have obtained permits from the municipality.More information on landfill history in the
United States can be found at [
3].
The
Resource Conservation and Recovery Act is a US federal law that is designed to protect the public from harm caused by waste disposal.
In the late-
20th century, alternative methods to waste disposal have been suggested, including
recycling, converting to
biodegradable products,
incineration and
cogeneration facilities, all of which assist in reducing the total amount of wastes disposed in to landfills. Some countries, such as
Germany,
Austria, and
Switzerland, have entirely banned the disposal of untreated waste in landfills in the early 2000's; there, only the ashes from incineration or the educt of mechanical biological treatment plants are still deposited.
Bioreactor landfilling is a process in which water is injected (as well as leachate being recirculated) into a specially-designed landfill to cause accelerated decomposition. The intention for this type of landfill operation is to maximise generation of
landfill gas (biogas) (which is captured using a network of perforated pipes and burnt to generate energy), as well as rapid stabilisation of organic waste material (in order to minimise the length of time required to manage the site, and/or to make use of the decomposed material as
compost).
The
Burlington County EcoComplex in
New Jersey makes extensive use of this technology, as does the
Woodlawn Bioreactor in
Queensland,
Australia.
*
Agriculture Street Landfill,
Louisiana*
Carleton Farms Landfill,
Michigan*
Fresh Kills Landfill,
New York*
Hiriya,
Tel Aviv*
Munisport,
Florida*
Pulau Semakau,
Singapore*
Randolph Farms Landfill,
Indiana*
Landfill gas *
Landfill tax*
Leachate*
List of solid waste treatment technologies*
Mechanical biological treatment*
Waste management
