Landfill
Landfill is a carefully designed structure built into or on top of the ground in which trash is isolated from the surrounding environment (groundwater, air, rain). This isolation is accomplished with a bottom liner and daily covering of soil.
The purpose of a landfill is to bury the trash in such a way that it will be isolated from groundwater, will be kept dry and will not be in contact with air. Under these conditions, trash will not decompose much. A landfill is not like a compost pile, where the purpose is to bury trash in such a way that it will decompose quickly.
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[edit] Operations
When the garbage is placed on the landfill, it is compacted three to five times. Compacting the garbage helps to prevent fires from starting in the garbage and it keeps rats away. The landfill also has only a limited amount of space, so compacting garbage also allows more garbage to be sent there.
After compacting the garbage, the operators of the landfill cover up all the new garbage in a five-inch layer of dirt. This helps to keep birds, seagulls, and rats away. It also reduces the odor that the landfill puts out to the surrounding community.
The landfill is built in the shape of a bathtub. It has a four to five foot layer of clay and a 60-milliliter layer of plastic lining. This ensures that no contaminated water from the landfill will enter the water supply. To further protect against this, the landfill operators remove water from the landfill every day and send it to a treatment center.
Eventually, the landfill will reach its capacity and it will not be possible to place any more garbage on it. At that point, the garbage will be covered up with grass and the area will be used as a skiing area, golf course, model airplane flying field, or bike trail.
[edit] Composition
There are four critical elements in a secure landfill: a bottom liner, a leachate collection system, a cover, and the natural hydrogeologic setting. The natural setting can be selected to minimize the possibility of wastes escaping to groundwater beneath a landfill. The three other elements must be engineered. Each of these elements is critical to success.
[edit] Secondary pollution generated from landfill site
In general people do not want a landfill site to be constructed near their living places because it causes more or less negative impacts on the environment and local people.
- Water contamination - leachate generated from landfill site, if not treated, contaminates river, sea and underground water.
- Gas generation - main gases generated from the landfill site are methane, ammonia, hydrogen sulfide and carbon dioxide.
Offensive odors - there are two type of offensive odor generated from the landfill site. One is the odor generated from waste itself and the other is gases generated through waste decomposition.
- Pests and vectors - kitchen waste tends to be the hotbed for flies, and attracts rodents and crows.
- Noise and vibration - incoming waste transport vehicles and landfill equipment may be sources of noise and vibration.
- Fire - may occur spontaneously due to methane gas generation or use of chemicals. Fire also may be caused by scavengers or other people.
[edit] Effectiveness of cover landfill method
- Prevention of waste scattering.
- Prevention of offensive odor.
- Control of rodents and vectors.
- Prevention of fire and its spreading.
- Improvement of landscape.
- Decreases in leachate generation.
[edit] Health Effects
Living in proximity to a poorly maintained landfill or hazardous waste site can cause serious health effects, especially in children. Health effects from exposure to hazardous waste can include:
- Cancer
- Birth defects
- Genetic mutations
[edit] Impact on Biodiversity
Any waste landfill means the subsequent elimination of a number of 30 to 300 species (microbiological population of the soil not included) on each hectare of the area intended to host a landfill. Moreover, changes are likely to occur in biocoenoses nearby the landfill, such as:
- ruderal species that are specific to polluted areas would become dominant in the vegetal assemblies;
- some mammals, birds, insects would desert the area, in favour of beings that feed on refuse (rats, crows).
Although the effects on flora and fauna are, in theory, time limited to the period over which the landfill is operated, the ecological reconstruction performed after the area has been relieved from its technological use will not be able to retrieve the initial biological balance, as the evolution of that biosystem has been irreversibly modified.
