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Organic waste disposed of to landfill can be an
environmental nuisance as chemical and biological processes
occur.
These processes convert or degrade waste into harmful products
of waste decomposition such as methane and leachate.
Methane is a combustible gas, and leachate is a toxic liquid
that can penetrate the ground and contaminate aquifers; the source
of our water supply.
What we are doing
Under the Environmental Protection Act 1990 the council has an
obligation to monitor, analyse and, where necessary, take remedial
measures at its closed landfill sites.
Kent County Council has two officers who carry out these duties
at 18 sites.
This involves checking equipment that has been installed on and
around the sites to monitor any gas migration, and seven of these
sites have systems in place whereby gas is controlled by burning it
off at a flare unit.
Water samples are also regularly taken from site and sent to a
laboratory where they are tested for pollutants.
These actions give a good indication of what is happening within
the site and will continue for many years after the site
closes.
Restoration of landfill sites
The period needed for a site to become stable depends on many
factors including:
- the type of waste landfilled
- its degree of compaction
- amount of moisture present
The lifetime of a landfill site is often in excess of twenty
years, and during that time a restoration plan for the site is put
into operation to meet the environmental needs of the area.
One aim of restoration is to control leachate generation by
minimising the amount of water getting into the site, and this is
achieved by installing a clay cap over the whole of the site.
When a site is stabilised it is sometimes possible to utilise
the land for informal recreation, public open space or low level
agricultural uses such as grazing. |