Landfill Waste

Over recent years our landfill estate has been reducing in size as more waste is recycled or used as fuel in Energy from Waste facilities. This pattern can be seen across the UK as part of the general drive to divert more recyclable and combustible waste from landfill. Although, the UK has a substantial shortfall of recycling and energy from waste infrastructure, meaning landfill disposal still plays an important waste management role to help the economy function.

There are also substantial volumes of residual waste from the economy which are not recyclable or suitable for fuel use and which will always have to be safely disposed of by landfill, along with residues from waste treatment and recycling facilities themselves.

Biffa is one of the main operators of landfill services in the UK. In the last year we handled around 3.6 million tonnes of waste through our 11 remaining operational landfill sites. These sites have a total remaining void of 40M cubic metres. We also manage 62 closed landfill sites in the UK.

Landfill Restoration

Whilst operating, most of our landfill waste sites host regular liaison meetings with local community representatives and stakeholders to help explain operations and address any concerns.  Once our landfills are full and stop taking waste, they are capped and restored. This is done in accordance with the Planning Permission and Environmental Permit requirements, typically to after-uses such as agriculture, nature conservation, woodland or public amenity, or combinations of those uses.  Long term environmental monitoring and aftercare management is also carried out in accordance with our Environmental Permit requirements.

The supporting role of landfill in the Waste hierarchy

Biffa supports the principles of the Waste Hierarchy aimed at maximising waste prevention at the top of the hierarchy and minimising waste disposal at the bottom.  But it's important to remember it is a hierarchy with levels which all serve a vital role. And whilst landfill disposal now has a much reduced role, it still provides an essential support function, which cannot be completely avoided.

Current landfill UK resources need protection and, when exhausted, need replacement.  For some specific businesses “zero landfill” may be possible, but for most and for the UK as a whole it is not.  Landfill disposal infrastructure is still required for non-combustible, non-recyclable wastes. Recycling and residual waste treatment facilities still need landfill outlets for process residues and for contingency during their annual maintenance down times.

Waste management

The role of landfill can be considered at three broad levels in terms of its waste management function:
  • Specialist: dealing with specialist and difficult wastes for which disposal by landfill is the appropriate means of disposal, e.g. asbestos and asbestos contaminated wastes, industrial sludge's and filter cakes, contaminated soils and various inert wastes.
  • Supporting: dealing with process residues and fines from energy recovery and recycling plants and general waste back-up during treatment plant down times; assisting with flexible and localised waste management solutions where other options are unavailable.
  • Bridging: helping to bridge the current and continuing waste treatment infrastructure capacity gap in the UK (the difference between residual waste arisings and available non-landfill waste treatment capacity).
Contact your local Biffa waste management team today and we will be happy to answer any of your questions on landfill waste.  

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Landfill Cells

A landfill site is built from a series of engineered cells. To prepare the ground in each cell, before waste is deposited, an engineered lining system is installed across the base and sides of each cell. The construction of the cell has to be approved by the regulator; a third party consultant provides a construction quality assurance report which the regulator reviews and signs off prior to any waste being tipped in the cell.  The purpose of the engineering is to prevent pollution of the surrounding area by containing any harmful contaminants.  Landfill cell preparation and lining works would typically include:

  1. Surface soils removal and excavation of the cell.  Most landfills involve filling in quarry excavations to help fill and restore the site after the minerals have been dug out, so the excavation is usually done by the quarry operator and the landfill engineering and filling by the landfill operator.
  2. Following excavation of the mineral, the quarry/cell floor is evened out and suitable material used to create a smooth, safe surface for the lining.
  3. A layer of clay is then put down to provide an excellent impermeable material that helps to prevent liquid from escaping.
  4. The third layer is a plastic liner
  5. Geotextile, a carpet like material, is then placed over the plastic to provide further protection.
  6. Gravel is then placed to create a drainage layer at the bottom of the cell, enabling water (rain) which filters through the waste when the cell is operational to be collected and removed.  This contaminated water is called leachate.

The precise details of the lining system may differ from site to site, depending on the setting of the site and local geology.  The site-specific engineering design is determined through consultation with the regulator, based on site-specific risk assessments.

Waste Fill

Once the cell is engineered it can start to be filled with waste.  This waste is typically from local homes, communities and businesses and is mainly the waste which is left over after materials suitable for recycling have been collected.  After a lorry tips waste into a cell, a compactor rolls over the waste to compress it and help the fill the space efficiently and evenly.

Cell Layers

Each cell is built up with waste, layer by layer. At the end of each stage and working day the surface is covered with suitable material like waste soils or fine material, to help control odour and litter and to keep the waste in place until more waste can be placed on top to complete the cell.

Gas Extraction

When waste decomposes it produces landfill gas (mainly methane). This has to be safely collected and managed for pollution control reasons but it can also be used to generate renewable energy (electricity), which is then supplied to the national grid power network, or sometimes directly to a neighbouring business. Landfill gas extraction wells are inserted into the cell to enable this gas to be collected and supplied to the gas engines compound.

Gas Conversion Into Renewable Energy

The landfill gas is collected through the gas extraction pipework system across the landfill site to the gas engine compound.  Here the gas engines convert the gas into renewable energy (electricity) which is then exported to the national grid or to local power uses.

Water Collection

The contaminated water (leachate) from rain which seeps through the waste accumulates in the bottom of each cell where it is collected through the drainage layer and pumped to the leachate treatment plant for on-site treatment, or to storage tanks prior to being before taken off site for treatment.

Cell Cap

When a cell has been filled to the correct level the area is capped with a permanent impermeable layer, typically another plastic layer but sometimes clay, before the surface restoration and landscaping is then carried out.

Surface Restoration

Surface restoration involves the permanent cap, protection layer and suitable clean soils before then carrying out whatever landscaping is required by the site’s approved restoration scheme, to achieve the required after-use.  This will typically be a combination of grassland with areas of tree planting and nature conservation habitat but varies from site to site.

Where large areas of tree planting are required grass seed will often be sown initially to create an initial green cover, with tree planting following later, once most of the landfill settlement has occurred.  Once restored, the site and the gas and leachate control systems are still managed for many years in accordance with the site’s Environmental Permit.

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