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Landfill
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A landfill, also known as a 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 organized 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.
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A landfill, also known as a 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 organized 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
- 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 voidspace 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.
- Protection of soil and water through:
- 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:
- 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 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. 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 daily cell. Waste compaction is critical to extending the landfill life. 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 Building at Sierra Point, Brisbane, California. The underlying fill was deposited from 1965 to 1985, mostly consisting of construction debris from San Francisco and some municipal wastes. Aerial photographs prior to 1965 show this area to be tidelands of the San Francisco Bay. A clay cap was constructed over the debris prior to building approval.
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 Japan, and will be used at a planned facility in St. Lucie County, Florida.
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 vectors 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.
Impact on people near landfills in the U.S.
Poorly constructed and operated landfills persist with leachate breaks, uncovered trash, and unchecked banned hazardous compounds. Federal laws to protect the public in Sec. 4001, Subtitle D of the Resource Conservation and Recovery Act (RCRA)
can be unenforceable to citizens without adequate legal funding. The U.S. Environmental Protection Agency generally relies on the states to enforce their own operating permits and federal laws. If state agencies are not aggressive, violations can worsen, multiplying negative environmental impacts exponentially. There are some notable recorded violations in the U.S., such as for a landfill in Hawaii that was fined $2.8 million in 2006 for operating violations, but this is not common. In Harford County, MD, the county municipal landfill has consistently operated in violation of its operating permit with the for many years, as shown in citizen documentation and photos on a community Web site called . In 2008, MDE officials found citizen documentation of poor conditions at the landfill to be credible and began steps toward a solution requiring legislation. Legislative solutions can be lengthy and may not necessarily guarantee state or federal enforcement.
Regional practice
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 Landfill in Staten Island, which is claimed by many to not only be the world's largest landfill, but the world's largest manmade structure.
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 waste with soil. 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 burned 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.
The Resource Conservation and Recovery Act is a US federal law that is designed to protect the public from harm caused by waste disposal. The EPA runs a Landfill Methane Outreach Program (LMOP), a voluntary assistance program that helps to reduce methane emissions from landfills by encouraging the recovery and use of landfill gas as an energy resource.
As of 1993, U.S. landfills consist of 40% to 50% paper waste, 20% to 30% construction debris, and 1.2% disposable diapers.
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 to 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 Germany, Austria, Belgium, 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.
See also
External links
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