How will the Landfill Directive affect engineering standards on UK sites?

The implementation of the EU Landfill Directive in the United Kingdom is now imminent. Operators of existing landfill sites should start to consider how they intend to meet the new standards set out in the Directive, in preparation for submitting a "conditioning plan" to the Environment Agency in less than 18 months time. Nick Davies, Principal Development Manager, AIG Consultants Ltd, discusses the likely impact of the Landfill Directive on engineering standards in waste management

The minimum standards for engineering are set out in Annex I of the Directive and reproduced in table 1 overleaf. Most modern landfill sites meet with the minimum engineering requirements for non-hazardous waste disposal facilities, however, the requirements for hazardous waste disposal engineering (i.e. a minimum liner thickness of 5 metres) is a significant departure from currently accepted practice.

In addition to the above there are specific requirements for leachate management and gas control with the requirement for all landfills receiving biodegradable waste to treat and where possible produce energy from landfill gas.

Perhaps the most interesting challenge facing engineers, if not the industry, is the banning of the disposal of hazardous and non-hazardous wastes, a practice currently referred to as co-disposal.

The implementation of the directive will require each of these waste categories to be disposed of separately. This requirement has led to a discussion whether a current co-disposal facility could be operated as both a hazardous waste and non-hazardous waste disposal facility. It is the Government's initial view that this scenario may be possible providing that both elements of the landfill site could be regarded as separate facilities with complete engineered separation and as far as possible separate management systems and separate landfill permits. However, it appears that there remains some convincing to do on behalf of landfill operators.

If accepted this is likely to result in a significant change in cell configuration and geometry with barrier systems having to be designed to different standards within the same site.

'Conditioning plan' deadline
All landfill site operators are required to submit a Landfill Directive 'conditioning plan' addressing the above issues by no later than the 16 July 2002. This plan must contain information on how the site will comply with the requirements of the Directive and any corrective measures to be taken for this purpose. The Environment Agency has the power to close sites, which in its view are unable to meet with the standards set by the EU Directive.

For existing sites where it would be difficult to engineer a barrier at the base of the site retrospectively, operators will have to demonstrate through risk assessment that there is no unacceptable risk to the environment or human health in order to maintain its operational status.

Notwithstanding this the Environment Agency will seek in all cases through the conditioning plan procedure to ensure that all that can be reasonably be done by the operator to bring the site within compliance with the directive is being done and as soon as possible.

In addition to the above requirements, landfill operators will have to review waste acceptance procedures and their environmental monitoring plans in order to ensure that they too meet with the specific requirements of the directive.

Finally, the Environment Agency will require all operators of sites, which have not been identified for closure through the condition plan process to submit a Pollution Prevention and Control application for the site within a specified time period.

If both the conditioning plan and the PPC application are satisfactory then a PPC Permit will be issued and the site will transfer to the new regime. Any improvement works required for the site to meet the landfill directive requirements will be as set out in the conditions of the PPC Permit.

It is envisaged that all PPC applications will have been determined by 2006, the latest deadline for existing sites to comply with the engineering standards of the Directive is July 2009.

Cost burden
The DETR estimates that the preparation of conditioning plans will place a one-off cost burden between £7-36 million on the landfill industry.

Operators of all 2,500 licensed landfill sites in the United Kingdom are likely to be affected by the Directive and it would be wise to take advice and start planning for the preparation and submission of conditioning plans by the deadline which is now less than 18 months away.

Information in this article is taken from the DETR's consultation paper The Implementation of Council Directive 1999/31/EC on the Landfill of Waste.

Table 1

The landfill base and sides shall consist of a mineral layer which satisfies permeability and thickness requirements with a combined effect in terms of protection of soil, groundwater and surface water at least equivalent to one resulting from the following requirements:

Landfill Type Permeability Liner Thickness
Hazardous waste K ≤ 1.0 x 10-9m/s Thickness ≥ 5m
Non-hazardous waste K ≤ 1.0 x 10-9m/s Thickness ≥ 1m
Inert waste K ≤ 1.0 x 10-7m/s Thickness ≥ 1m
m/s: metre/second

In addition to the geological barrier described above a leachate collection and sealing system must be added in accordance with the following principles so as to ensure that leachate accumulation at the base of the landfill is kept to a minimum.

Leachate collection and bottom sealing

Landfill Category Non-hazardous Hazardous
Artificial sealing liner Required Required
Drainage layer ≥ 0.5m Required Required

If the competent authority after consideration of the potential hazards to the environment finds that the prevention of leachate formation is necessary, a surface sealing may be prescribed. Recommendations for the surface sealing are as follows:

Landfill Category Non-hazardous Hazardous
Gas drainage layer Required No required
Artificial sealing layer Not required Required
Impermeable mineral layer Required Required
Drainage layer ≥ 0.5m Required Required
Top soil cover .1m Required Required



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