Term Papers on The Choosing Of A Landfill Site

Term Paper Title	The Choosing Of A Landfill Site
# of Words	3099
# of Pages (250 words per page double spaced)	12.4

The Choosing of a Landfill Site

There is currently much debate on the desirability of landfilling particular
wastes, the practicability of alternatives such as waste minimisation or pre-
treatment, the extent of waste pre-treatment required, and of the most
appropriate landfilling strategies for the final residues. This debate is likely
to stimulate significant developments in landfilling methods during the next
decade. Current and proposed landfill techniques are described in this
information sheet.

Types of landfill

Landfill techniques are dependent upon both the type of waste and the landfill
management strategy. A commonly used classification of landfills, according to
waste type only, is described below, together with a classification according to
landfill strategy.

The EU Draft Landfill Directive recognises three main types of landfill:

     Hazardous waste landfill
     Municipal waste landfill
     Inert waste landfill

Similar categories are used in many other parts of the world. In practice, these
categories are not clear-cut. The Draft Directive recognises variants, such as
mono-disposal - where only a single waste type (which may or may not be
hazardous) is deposited - and joint-disposal - where municipal and hazardous
wastes may be co-deposited in order to gain benefit from municipal waste
decomposition processes. The landfilling of hazardous wastes is a contentious
issue and one on which there is not international consensus.

Further complications arise from the difficulty of classifying wastes accurately,
particularly the distinction between 'hazardous'/'non-hazardous' and of ensuring
that 'inert' wastes are genuinely inert. In practice, many wastes described as
'inert' undergo degradation reactions similar to those of municipal solid waste
(MSW), albeit at lower rates, with consequent environmental risks from gas and
leachate.

Alternatively, landfills can be categorised according to their management
strategy. Four distinct strategies have evolved for the management of landfills
(Hjelmar et al, 1995), their selection being dependent upon attitudes, economic
factors, and geographical location, as well as the nature of the wastes. They
are Total containment; Containment and collection of leachate; Controlled
contaminant release and Unrestricted contaminant release.

A) Total containment

All movement of water into or out of the landfill is prevented. The wastes and
hence their pollution potential will remain largely unchanged for a very long
period. Total containment implies acceptance of an indefinite responsibility for
the pollution risk, on behalf of future generations. This strategy is the most
commonly used for nuclear wastes and hazardous wastes. It is also used in some
countries for MSW and other non-hazardous but polluting wastes.

B) Containment and collection of leachate

Inflow of water is controlled but not prevented entirely, and leakage is
minimised or prevented, by a low permeability basal liner and by removal of
leachate. This is the most common strategy currently for MSW landfills in
developed countries. The duration of a pollution risk is dependent on the rate
of water flow through the wastes. Because it requires active leachate management
there is currently much interest in accelerated leaching to shorten this
timescale from what could be centuries to just a few decades.

C) Controlled contaminant release

The top cover and basal liner are designed and constructed to allow generation
and leakage of leachate at a calculated, controlled rate. An environmental
assessment is always necessary to that the impact of the emitted leachate is
acceptable. No active leachate control measures are used. Such sites are only
suitable in certain locations and for certain wastes. A typical example would be
a landfill in a coastal location, receiving an inorganic waste such as bottom
ash from MSW incineration.

D) Unrestricted contaminant release

No control is exerted over either the inflow or the outflow of water. This
strat...

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