Landfill: Difference between revisions

Landfill Technology and Evolution

Landfill sites have usually been constructed in disused quarries, or parts of quarries. However, the phrase is also used to describe sites built where there had previously been no excavation. Such sites are also known as “land-raise” sites, but in the context of this website, no distinction has been made. To all practical intents and purposes, there is no significant difference between landfill and land-raise.

One definition of aquifer is as follows, quoted from Freeze and Cherry (1979): “An aquifer is best described as a saturated permeable geologic unit that can transmit significant quantities of wate under ordinary hydraulic gradients”. This definition captures the essence of the word very well.

In the England and Wales, the EA categorise aquifers to be consistent with the Water Framework Directive. The categories are Principal Aquifer, Secondary Aquifer and Unproductive Strata. Previously the phrases major aquifer and minor aquifer were utilised. Similar arrangements exist in Scotland and are supervised by SEPA.

The relevance of the hydrogeological setting within which a landfill is located arises from the need to assess the technical precautions required for a landfill to be authorised such that unacceptable environmental impacts are prevented. This assessment is undertaken via a Hydrogeological Risk Assessment (HRA); this is submitted as supporting document to an Environmental Permit application. Again, similar arrangements are in place in Scotland.

The technical precautions required to operate a landfill are incorporated into the landfill engineering design. The extent to which such technical precautions are required depends upon the needs established in the HRA. Notwithstanding that, there are minimum requirements imposed by the Landfill Directive and subsequent UK legislation – The Landfill (England and Wales) Regulations 2002.

Historically, landfills did not require engineering and such sites without an engineered lining system are commonly described as “dilute and disperse”. Notwithstanding the lack of site engineering, some evaluation of their pollution potential was undertaken. This mainly consisted of a simple evaluation of the ability of the surrounding geology to adsorb contamination to determine likely consequential pollution effects. This evaluation considered the ability of the ground to “dilute and disperse” the impact of the site, hence the common name.

WMP27 deals with methods for management of landfill gas.

Electricity generated from landfill gas can be used on-site and also be supplied to the National Grid for re-sale.

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