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===Landfill Engineering===
===Landfill Engineering===
Complex
Landfill engineering is a phrase used to describe the preparation and on-going engineering required to operate a landfill site.
What is required at any particular site depends upon the proposals made by the permit holder in order to be granted an Environmental Permit and any subsequent modifications agreed between the permit holder and the regulator (EA, NRW or SEPA).<br>


Include Landfill cell
The technical precautions required to operate a landfill are incorporated into the landfill engineering design. Notwithstanding that, there are minimum requirements imposed by the Landfill Directive and subsequent UK legislation – The Landfill (England and Wales) Regulations 2002.<br>


Include '''Containment Facility'''/''Landfill Lining System''
The design will have been produced taking heed of the technical precautions required to satisfy the regulator that the site will not have an unacceptable impact upon the environment and  that the approved design will comply with the requirements of the Landfill Directive. These precautions will have been validated against the various risk assessments required to accompany a permit application.<br>


'''Dilute and Disperse'''
Usually the application will be accompanied by risk assessments of the hydrogeological impact of the site, the potential for landfill gas release and the stability of any engineering designs proposed. There will be additional risk assessments required for operational matters such as dust, noise and amenity impacts; these are largely managed by operational techniques, but occasionally there will be elements of mitigation required that constitute site engineering (e.g. the construction of noise bunds).<br>
 
Sites which were authorised historically 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.<br>
 
Landfill engineering design evolved in the 1980s, such that new dilute and disperse sites became less likely to be granted consent to operate. At the time, this was not supported by the implementation of any new specific legislative drivers, the principal legislation remaining the Control of Pollution Act 1974. This required landfills to be licensed by local authorities. In assessing licence applications, local authorities were required to ensure the prevention of pollution to water and danger to public health. This requirement established a rationale for assessment and its implementation evolved over the period from 1976 onwards.<br>
 
Landfill sites that incorporate engineered barriers are known as “containment facilities”. The design of such facilities has more than one form and can incorporate different numbers of layers and different designs. These layers are conventionally known as the “landfill lining system”.<br>
 
The Department of the Environment produced a series of Waste Management Papers (WMP) over the period from the late 1970s to 1997. WMP 26B contains a review of the types of designs. The design employed at any particular design would be informed by the outcome of the HRA which would assess the likely impact of a site upon the environment taking account of the design proposed. In general terms, the most sensitive sites would require the greatest degree of engineering.<br>
 
Landfills are constructed in discrete parts known as “landfill cells”. The sub-division into cells is undertaken so as to minimise the operating area and consequently minimise leachate generation and make the site more manageable in terms of odour and litter control. Sub-division also enables the site engineering to be constructed progressively as the site fills.


===Landfill Gas===
===Landfill Gas===