Contaminated Land
Landfill Sites
A landfill is an area of land where people have disposed of
waste material. People have been landfilling waste in local tips
for thousands of years, but it is generally only in the last
century that large scale landfilling has had the potential to
significantly impact on the environment.
The proximity of a landfill to a property or site has
implications for developers who will need to ensure that any new
development is adequately protected from landfill gas. Information
on landfilling activities is therefore one of the main components
of an environmental search.
A brief history of waste regulation in the UK
Waste disposal regulation in the UK began with the introduction
of the 1848 Public Health Act. The Act made provision for waste to
be stored in 'Midden Heaps' located next to people's houses.
'Midden Heaps' were large holes in the ground into which rubbish
and sewage was thrown. When the pits were full, they were dug out
and the waste taken away by horse and cart.
The major change in waste collection came soon after in the
publication of the 1875 Public Health Act. The Act was introduced
as a direct result of a cholera outbreak in London, which had
claimed many lives. The main focus of the 1875 Act was to charge
Local Authorities with the responsibility for removing and
disposing of waste.
The introduction of The Clean Air Act in 1956 placed new
restrictions on the burning of waste. This led to a change in the
composition of the material disposed of in landfill sites as
previously most domestic waste was burnt prior to disposal as
ash.
In 1974 the Control of Pollution Act meant that all landfill
sites had to be licensed and for the first time, details of the
type and volume of waste was recorded.
Since 1994, waste disposal has been tightly regulated by Waste
Management Regulations. Modern landfill sites are regulated by the
Environment Agency and are highly engineered structures, designed
to contain and manage the waste and waste products. They can also
be used to generate electricity from landfill gas.
Today, the UK National Waste Strategy is promoting a more
sustainable way in which we manage our wastes. European Union and
UK Government targets have been set which aim by 2020, to reduce
the amount of biodegradable municipal waste which it landfills to
35 percent of that produced in 1995. This will be achieved by a
combination of, recycling, reducing packaging, composting and
re-using materials.
What are the main risks associated with landfills?
Each landfill is different and can vary in age, type and volume
of waste filled, proximity to receptors and how well it has been
engineered. However the main risks associated with landfilling are
common to all landfills and can be classified as either pollution
of surface waters and groundwater by leachate from the filled
material or health effects and explosive risks from landfill
gas.
Leachate forms within a landfill when waters circulating through
the waste pick up different contaminants. In older landfills where
leachate is not contained it may migrate from the landfill and
cause pollution of the ground water or surface waters.
Landfill gas is a breakdown product from the putriscible
component of domestic waste e.g. food, garden waste, wood and
paper. The principal reaction occurs when bacteria break down the
organic matter into methane and carbon dioxide. The potential for a
site to produce gas is dependent upon the age of the site and the
nature of the fill. The potential for gas to migrate from the
landfill depends on whether the site has been properly engineered
in order to manage the gas which is produced.
There are many hundreds of trace gases that can also be produced
from a landfill site, but following normal atmospheric dilution
most do not usually represent a health hazard. The more common
trace gases include hydrogen sulphide and carbon monoxide.
What can be done to reduce the risks from landfills?
Leachate can be pumped and treated before it leaves a landfill
and should therefore not cause any further problems. This typically
occurs in older landfills where no containment systems have been
put in place.
Landfill gas may give rise to a variety of hazards if it
migrates to, and accumulates in, a property or confined space. If
generated in sufficient quantities, methane gas may form an
explosive mixture with air (at approximately 5-15% by volume). It
can also act as an asphyxiant and in particular circumstances may
be toxic. Carbon dioxide is an asphyxiating gas which can cause
adverse health effects even at relatively low concentrations.
In modern landfills the installation of gas management systems
such as venting or extraction measures will significantly reduce
the risk of gas migration to neighbouring properties.
The incorporation of protective measures such as a sub-floor
void and gas resistant membranes within neighbouring buildings will
also reduce potential risks associated with landfill gas. The need
to incorporate such measures into new developments is addressed
through the planning procedure.
What is being done about old landfills that have no containment
measures?
Detailed information for sites which were completed prior to the
1974 regulations is often scarce. Your Local Authority will be
examining old or closed landfills in their area as part of their
Contaminated Land Inspection Strategy and will be addressing any
risks in due course under Part IIA.
What are closed landfills used for?
Most closed landfills are returned to public open space or used
for the grazing of livestock. Some of the older inert landfills,
which pose little risk are being developed for commercial and
industrial use.
Further Information
Further information may be available from the Council, please
contact the Contaminated Land Officer for details.
Contact
Email: envhealth@dover.gov.uk
Telephone: 01304 872230
