Landfilling of Waste 3. Definition of Landfills3.1 Definition and strategy Landfills are delimited constructions where waste can be landfilled under controlled and environmentally sound conditions. Before being landfilled the waste must have been inspected and checked. 3.1 Definition and strategy "Landfill" is a collective term for facilities subject to authorisation for the landfill of waste. Landfills are sites where various types of waste can be gathered and an effective waste control carried out to ensure that the landfilling is environmentally optimal. A landfill must be established with landfill units corresponding to a division of waste into various types the properties of which are - directly or after pre-treatment - of the same nature. This system allows for differentiated management of the leachate from different types of waste. Furthermore, a higher degree of specific control of the waste at the tip face is achieved - so as to ensure that the waste is placed in the proper landfill unit. Landfill units are established with different environmental protection measures - in terms of operation and/or design - depending on the nature which the waste is expected to have. Each landfill unit is subdivided into cells; the size of the cells is determined by constructional and operational conditions. If large quantities of a single type of waste are to be landfilled, a mono-landfill may be established. The environmental protection systems are adapted to the type of waste. Every landfill represents a potential pollution risk during the period until leachate from the waste is acceptable in the surroundings. Therefore, if some of the active environmental protection systems fail, measures must be taken to ensure that the groundwater and surface water are not affected. Landfills should be located, primarily, just behind the coastal zone and in areas with limited drinking water interests, see Chapter 5: "Preliminary Investigations". Active and passive environmental protection systems are defined in Chapter 6: "Layout". 3.2 Landfill units A landfill may consist of a number of units where specified types of waste are received - or it may be a mono-landfill for a single type of waste. Landfills may be laid out with active or passive environmental protection systems depending on the type of waste it is intended to receive. 3.2.1 Landfill unit A landfill unit is a delimited and well-defined area where types of waste with uniform composition and leaching behaviour are placed together under controlled, environmentally sound conditions. Subdividing the landfill into landfill units provides access to perform specific control of the types of waste landfilled in each unit. Each landfill unit is equipped with facilities for separate leachate management and different levels of environmental protection systems - corresponding to the types of waste which the unit is expected to receive. In practice, a typical landfill could be expected to contain the landfill units indicated in Table 3.1. Active environmental protection systems are pre-evaluated in relation to the type of waste in question. Under normal circumstances, active environmental protection systems will include collection and disposal of leachate. Passive environmental protection systems can be used as the sole system only where a careful assessment has been made of the geological and hydrogeological conditions in the area around the relevant site - and where the impact on and possible risks to the environment have been assessed in advance, particularly on the basis of knowledge of the waste, and found acceptable. In cases where it may be necessary to landfill waste with a high organic content, a landfill unit at the facility must be laid out as a "bioreactor landfill". The operation of such a unit must be arranged so that the decomposition of the organic waste is optimised with a view to recovery of the generated methane gas for energy purposes. Annex C contains a description of a "bioreactor landfill". Table 3.1. Landfill units with examples of the nature and categories of waste, and the environmental protection systems.
3.2.2 Mono-landfill A "mono-landfill" is a landfill which receives only one specified type of waste under controlled and environmentally sound conditions. The type of waste must be known with regard to origin, composition and likely leaching behaviour. Mono-landfills are used where there is a need to dispose of exceptionally large quantities of a single type of waste from one or a few sources. A mono-landfill must be laid out as one landfill unit with active and/or passive environmental protection measures adapted to the composition of the particular type of waste and its expected leaching behaviour. Active environmental protection systems are pre-evaluated in relation to the type of waste in question. Under normal circumstances, active environmental protection systems will include collection and disposal of leachate. Passive environmental protection systems can be used as the sole system only where a careful assessment has been made of the geological and hydrogeological conditions in the area around the relevant site - and where the impact on the environment has been assessed in advance, particularly on the basis of knowledge of the waste, and found acceptable. Table 3.2 provides examples of different mono-landfills. Table 3.2 Examples of mono-landfills.
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