Landfill

Related Topics:
Landfills :: Landfill_Gas :: Landfill

For other uses see: Landfill (disambiguation).

A Landfill is a site for the permanent disposal of waste materials by burial. 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 ^*.

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.

Landfill types & construction

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.

Landfill 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 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.

Landfill operations

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.

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.

Impacts of Landfills

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 ^*.

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.

Landfill in the United States

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 ^*.

The Resource Conservation and Recovery Act is a US federal law that is designed to protect the public from harm caused by waste disposal.

Alternatives to Landfill

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

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 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.

Landfills around the world

References

Soil contamination | Landfills | Waste | Waste management

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