Landfilling of Waste

2. Overall Landfill Strategy

Knowledge of the waste going to landfill and the location of the landfill are the most important factors of environmental protection in the landfill of waste.

The starting point for the strategy for waste landfilling is that each generation must deal with its own waste. At the same time, a "generation" is the realistic time horizon where active, environmental protection systems can be expected to work. Finally, it is the time horizon for the length of time where leachate management, optimum control, and inspection are likely to be carried out after closure of the landfill.

This implies that the landfilled waste must have a composition which renders it probable that leachate from the waste can be accepted in the surrounding groundwater within a time horizon of 30 years. During the period until leachate from the waste is acceptable in the surroundings, a landfill constitutes a potential source of pollution.

Because some of the active, environmental protection systems can fail, steps must be taken to ensure that the location of the landfill is environmentally acceptable.

Any expansion of existing landfills as well as the location of new sites must therefore be made in the light of a number of overall environmental considerations. The result of this is sites which are located, primarily, just behind the coastal zone and in areas with limited drinking water interests. If this location is not possible, a location closer to the coast may be the solution - except that the preservation of open stretches of coast and the regard for the interests in recreation, natural and cultural patrimony must be allowed for. Locations near watercourses and lakes and in the interior of the country should be avoided if at all possible.

Sites with a simple well-defined geology and hydrogeology should be preferred.

In order to gather the pollution potential from the landfilled waste in few places, waste must be landfilled in few facilities. It is therefore intended that the number of active landfills should be reduced (as per the Ministry of Environment’s letter of 27 December 1991 concerning the geographical location of landfills in connection with the 1993 revision of regional plans). This makes it possible to carry out a target-oriented and effective monitoring of the impact of the facilities on the environment.

Before waste is accepted at a landfill it must be rendered probable that leachate from the waste will be acceptable in the groundwater of the area within not more than 30 years and thereafter. If this is not the case, waste must be pre-treated in such a manner that the criteria can be met before landfilling.

Waste will be divided into types which can be expected – directly or after pre-treatment - to be of the same nature. There must be no mixing of different types of waste which could trigger processes that alter the knowledge of the nature and behaviour of the leachate with time.

Waste that can be treated in other environmentally sound manners by means of existing methods should not be landfilled. Waste suitable for incineration and recyclable materials therefore should not be landfilled. As from 1 January 1997 the Statutory Order on Waste contains a requirement for the local councils to provide regulations that assign waste suitable for incineration to this treatment option. As from the same date there is a requirement for the local councils to provide regulations that ensure source separation and recycling of construction and demolition waste.

Landfills are subdivided into landfill units. Landfill units are established with environmental protection systems adapted to the types of waste intended to be placed there.

In exceptional cases, a mono-landfill may be set up for large quantities of a single type of waste.

Basically, all leachate must be collected, treated and monitored from each individual landfill unit by means of active environmental protection systems. These systems must provide optimum environmental protection throughout the active phase of the landfill unit.

For this purpose "active environmental protection systems" are components such as liners, drains, pumps, discharge to treatment plants, etc. If these fail, optimum environmental protection is no longer achieved. Optimum environmental protection is necessary until leachate from the waste is acceptable in the groundwater or surface water. Until then, active environmental protection systems must be intact or capable of being replaced on an ongoing basis. Active environmental protection systems require monitoring.

Landfill units that are intended only to receive waste from which leachate will be acceptable in the surrounding groundwater at a given location can be established with reduced - or exclusively with passive - environmental protection systems. These landfill units can be accepted on the basis of detailed advance knowledge of the geological and hydrogeological conditions and wetland conditions around the given location - as well as of the leaching behaviour of the waste and an overall assessment of the impact on the environment.

Passive environmental protection systems are components which protect the environment without maintenance. These components may be embankment systems, low-permeable bottom liners, final covers, surface drains, vegetation, etc. Such systems are likely to remain effective for several hundred years.

Each unit in a landfill must receive a final cover as and when the individual cells of the unit reach the defined landscape profile.

The final cover must be adapted to the expected leaching behaviour of the waste. Tight final covers are unacceptable until the leachate has reached a stable condition that can be accepted in the surrounding groundwater.

The active systems of a landfill unit may become passive systems when the leachate from the individual unit becomes acceptable in the percolating water in the area surrounding the landfill. In each particular case this must be determined on the basis of an assessment of the impact on the surrounding environment.

The time when the landfill can go to passive operation is established in the light of concrete assessments of the relevant monitoring activities, and knowledge is obtained of the actual leaching pattern of the waste.

The most significant self-control for a landfill must be the control of waste received. Another important factor in connection with self-control is the supervision of the establishment of active environmental protection measures. During the phase when the environment protection systems of a landfill are active, the leachate must be monitored and controlled. When the active systems become passive ones, the monitoring and control of leachate may cease.

Control of the groundwater and wetlands around a landfill must verify that the pollution is no greater than assumed in the permit of the facility. The extent and duration of the control activities in the landfill’s passive phase are determined on the basis of a concrete assessment of the results of the controls as recorded during the landfill’s active phase and the actual leaching behaviour of the waste. The control activities are the responsibility of the owner of the landfill.