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.
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