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Landfilling

General information

Landfills are the final disposal site for different types of waste. A landfill is classified as a landfill for hazardous waste, non-hazardous waste or inert waste. In 2019, energy recovery was still the most significant method of treating municipal waste (56%), the proportion accounted for by material recovery was 43 per cent, while landfilling only accounted for approximately 0.7 per cent. In 2020, there were 419 operational landfills in Finland. It includes landfills of non-hazardous (99), hazardous (27) and inert waste (7), as well as landfills for soil and mining waste. Most of the waste placed in landfill sites was a different kind of mineral waste. Over half (235) of landfills in operation are landfills for soil and 64 were for mining waste. Landfill disposal of municipal waste is possible only for the exceptional cases. The materials deposited in landfills primarily include aggregate, asbestos, other fine particles (e.g. ash) and non-combustible waste.

The Government Decision on landfills (331/2013) restricts the placement of organic waste in landfill. According to it, waste, generated in housing and similar waste from the industrial, service and other activities in terms of its characteristics and composition, shall not be placed in landfill of non-hazardous waste, if most of the biodegradable waste has not been separated from other waste for recovery purposes. In addition, the Government’s decision restricts placing waste to landfills of inert and hazardous waste, as well as some non-hazadous waste landfills, based on the concentration of organic matter they contain. In certain situations, the licensing authority may grant exemptions from restrictions. Landfills for soil are not covered by the Government decision on landfills.

The most common method of exploitation of gas collected from landfills is heat production. In some plants, the gas was utilized in combined heat and electricity production. Limiting landfilling of the biodegradable and other organic waste will substantially reduce landfill gas formation and may reduce the need to establish new landfill gas pumping stations.

Photo: Solar panels on the slope of Tarastenjärvi decommissioned landfill

 

Landfills and waste legislation

In addition to the Waste Act and the Government Decree on waste, the landfill itself is covered by the Government Decree on Landfills 331/2013. Other legislation also has acts to be taken into account. The Government Decree 1022/2006 on substances hazardous and harmful to the aquatic environment may cause the need to monitor emissions of the substances specified in the Regulation. Activities that pose a risk of environmental pollution should have environmental permits. Those activities are such as professional waste management e.g. landfill construction. The permit is applied for electronically from the Regional State Administrative Agency’s permit service. The Regional State Administrative Agencies issue environmental permits for major waste treatment facilities, such as large-scale waste recovery and final treatment plants that treat non-hazardous waste, waste incineration plants, hazardous waste treatment plants and landfills.

If an application for the environmental permit concerns an activity which may have significant negative effects on the environment, the application needs to have a separate environmental impact assessment. E.g. landfills of hazardous waste, where an annual amount of waste will be at least 5 000 tons, always require an environmental impact assessment as an annex to the environmental permit. (Government Decree on the Environmental Impact Assessment Procedure 713/2006, Section 6)

Waste tax is levied on all waste deposited in landfills, provided that its recovery is environmentally justifiable and technically feasible and that it can be made more commercially exploitable by imposing the tax. All waste types subject to tax are specified in the Annex to the Waste Tax Act (1126/2010).

In Government Decree on Landfills 331/2013, Chapter 3, are General restrictions on the acceptance of waste to landfills.

Article 13: Landfill categories and waste to be approved for different landfills

A landfill is classified as a landfill for hazardous waste, non-hazardous waste or inert waste.

Only waste of that specific class is accepted for the landfill. However, this does not apply to:

  1. the recovery of suitable non-hazardous waste for construction purposes in a landfill;
  2. the recovery of other suitable non-hazardous waste in the surface structures of a landfill of inert waste or in the structures in the sealing layer or in the surface structures of a hazardous waste landfill; And
  3. cases referred to in Articles 30 or 31.

 

To inert waste landfills are placed the waste that does not biodegrade, dissolve, burn, or, after a long period of time, biologically, physically, chemically, or react to other substances, causing danger. Such waste includes glass, concrete, bricks, ceramics, soil and stone materials. Normal household waste is placed in the landfills of non-hazardous waste. (Government Decree on landfills 313/2013, Section 3, Annex 3.)

Hazardous waste landfills have waste which may pose a risk to the environment or health due to its chemical or other properties. Annex 4 to the Government Decree on Waste (179/2012) designates waste classified as hazardous. These include following types of waste:

  • substances and products which may explode under the influence of flame
  • flammable substances
  • oxidising agents
  • substances harmful and irritant to health;
  • toxic and carcinogenic substances
  • corrosive substances
  • substances and products hazardous to the environment
  • wastes which may generate harmful fluids

 

General assessment requirements

For the assessment of waste landfill eligibility, a three-level procedure shall be applied, divided into the following steps:

  1. a basic definition of waste which, using standardised methods, ascertain the characteristics of waste sufficiently to demonstrate that the waste meets the requirements for landfill defined for each category, and that the placement of waste to landfill is safe even in the long term;
  2. waste equivalence testing where standardised short-duration methods regularly measure the typical characteristics of waste identified in the basic definition to ensure that the waste meets the authorisation provisions;
  3. a waste inspection at the landfill to ensure that the waste corresponds to the documents presented.

 

The assessment of landfill eligibility shall be based on reliable data of the origin and characteristics of the waste. Assessment criteria for the characteristics include:

  1. the composition of the waste;
  2. the quantity and degradability of the organic matter in the waste;
  3. the quantity and solubility characteristics of the harmful substances in waste;
  4. ecotoxicological characteristics of the waste and the resulting landfill water.

 

Furthermore, the assessment shall be based on the following information on landfill:

  1. the characteristics and quality of the landfill site and the protection of its environment;
  2. the quality level of environmental protection arrangements and their ensuring;
  3. stability of waste filling and its ensuring;
  4. preventing the hazards that threaten human health.

 

Requirements for the structures

The landfill regulations define the requirements and thicknesses of structures (Government Decree on Landfills 313/2013, Section 6, Section 7, Appendix 1).

Based on the classification of the landfill, its intended use and general instructions, the structures of each landfill must be designed on a case-by-case basis. General structural differences per category of landfill are that the ground structure of a hazardous waste landfill is thicker, no artificial insulating layer is required for a landfill of non-hazardous waste, and the need for a gas collection layer in a hazardous waste landfill depends on the characteristics of the waste to be placed on site. (Government Decree on Landfills 313/2013, Annex 1.) Work report and environmental, quality, measurement and safety plans are carried out for each site.

 

Foundation and surface structures of the landfill

1. Requirements for sealing of foundation structures

The landfill soil (mineral soil or rock) shall meet the water permeability (K) and thickness requirements of the water saturated soil that their combined impact is at least equivalent to the following requirements:

  1. landfill of hazardous waste: K ≤ 1,0 x 10-9 m/s and thickness ≥ 5 m;
  2. landfill of non-hazardous waste: K ≤ 1,0 x 10-9 m/s and thickness ≥ 1 m;
  3. landfill of inert waste: K ≤ 1,0 x 10-7 m/s and thickness ≥ 1 m.

 

2. Layers of surface structures

Layer Non-hazardous waste landfill Hazardous waste landfill
Top layer ≥ 1 m Required Required
Drainage layer ≥ 0,5 m Required Required
Sealing layer ≥ 0,5 m Required Required
Artificial insulation Non Required Required
Gas Collection Layer Required When needed

 

When planning a landfill area, one must first find a suitable location for it. The Government Decree on Landfills (331/2013, Section 4), the Environmental Protection Act (527/2014, Section 11) and the Waste Act (Section 646/2011, Section 13) provide location restrictions and guidelines that must be taken into account in the planning.

The landfill shall not be located in areas classified by the Centre for Economic Development, Transport and the Environment as important groundwater areas or groundwater areas suitable for other water supply, unless it can be ensured that the groundwater quality of these areas does not suffer. In addition, the landfill shall not be located in areas where the movement of soil could cause damage to structures in the future or harm the after-care of the landfill. (Government Decree on Landfills 331/2013, Section 4.)

Areas such as this include areas with soft soil, marshlands and areas where there is the possibility of landslides or flooding. Areas such as protected areas for natural and landscape values, as well as areas protected for the preservation of national cultural heritage or natural heritage, also restrict the location of the landfill area. The selection of the area must also take into account sufficient distance from the settlement and urban areas. (Government Decree on Landfills 331/2013, Section 4.) In addition, the landfill must be suitable for the environment or landscape (Waste Act 646/2011, Section 13).

 

Closing of landfills

The Landfill Degree defines structures for landfill closure. The structures of the landfill closure are approved in an environmental permit based on the operator’s plans. Key legislative obligations are requirement for the construction of a capping structure, and requirement for capture of landfill gas, monitoring, and leachate treatment (generally for 30 years). Deviations are possible if the risk assessment is supporting them. Additional guidance can be found in the literature, published papers and standards. The ways landfill may have impact is by having a contact with waste, by vermin and/or other animals, by odour and gas release (CH4), and leachate. Proper closure needs to be done to bring a landfill to a stable and safe condition, reduce negative impacts and reduce need for active management.

Finnish implementation requires independent supervision during construction, which is paid for by the owner of the landfill. Quality of the construction is very important for achieving minimal environmental impact after closure. Quality of the material and supervision requirements are defined by the designer and standards. There need to be material proof of qualification and appliance to ISO standards; visual inspection by the independent supervisor; material samples and laboratory tests (especially HDPE/LLDPE liners) and on-site tests of seams and installation.

Closure design principles for the non-hazardous waste are that bottom layer (from bottom to top) includes compacted soil, mineral barrier layer ≥ 0.5m (1.0m for hazardous waste), HDPE liner 2 mm, drainage layer ≥ 0.5m and waste. Minimum thickness is 1.0 m and independent supervision of construction is needed. Capping layer for the non-hazardous waste landfill (from bottom to top) consists of compacted waste (slope <1V:3H), landfill gas collection layer, geotextile or bentonite mat or clay liner (for hazardous waste HDPE/LLDPE liner), drainage layer or mat, and top cover and vegetation layer. In Finland, minimum thickness is 1.5 m, preferably 2.0 m.

Landfill gas collection depends on the waste composition and gas potential. For the landfill gas there need to be a collection and utilization, collection and flaring or passive treatment through carbonization if quantities of gas are low. Generation of leachate decreases over time. Active treatment of leachate is needed if there is ongoing operation or quality requirements. Passive treatment after closure can be done if possible.

Monitoring and after-care are stipulated in an environmental permit and after-care period of 30 years is generally required. It consists of monitoring of landfill gas (frequency depending on collection system), surface water (quarterly), groundwater and landfill internal water level, and settling.

 

Case examples of closed landfills (you can find more examples on decommissioning and monitoring of landfills below):

 

Cold climate is also causing challenges. Freezing and thawing are impacting material properties, and causing uneven settling. There is limited construction time, basically during the summer. Efficient drainage and leachate management is of high importance and there may be challenges with passive treatment solutions. Permafrost areas are even more sensitive, especially when considering drainage. Potentially freezing over time will require significant capping thickness. Leachate production is reduced in colder climates and slow decaying of waste means low methane production (especially in permafrost areas).