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The Environment Agency Landfill Location Policy

Is there a way of developing new landfills on major aquifers?

Mineral operators are facing strict regulations on the restoration of extraction sites. Landfilling has been a viable and profitable option for many years. However, this is no longer possible for a large number of operations following Environment Agency (EA) guidelines on the location of landfills, set up in response to the Landfill Regulations, 2002.

The Landfill Regulations specify that, when granting planning permission for a landfill, consideration needs to be given to the geological and hydrogeological conditions of the area. While this appears reasonable, the EA’s interpretation of this means that all new sites, other than those only receiving inert wastes, cannot be developed on all major and, in certain circumstances, minor aquifers.

This interpretation is particularly important to the mineral extraction industry, as some of the principle aggregate products are sourced from quarries located in major and minor aquifers. For example, the EA has defined major aquifers as highly permeable formations that include limestones, such as the magnesian, Carboniferous and Lincolnshire limestones, chalk and (in the Middle Thames region) river gravels. Minor aquifers generally only have variable and lower permeability and include a wide variety of aggregate sources, such as the remaining river gravels, Thanet sand and millstone grit.

Given the prohibitive nature of the EA’s current interpretation of the locational aspects of the Landfill Regulations, it is important that mineral operators are aware of the potential implications. Without the option to landfill exhausted mineral sites with non-hazardous wastes, the operator has few options other than low-level restoration or infill with inert materials. Low-level restoration is often inappropriate and can provide an unsatisfactory final landform, while problems with sourcing of inert materials, such as clean subsoils, could limit the effectiveness of the infill option.

PRIOR TO THE PUBLICATION OF RGN3

The EA’s interpretation of the Landfill Regulations, 2002, is set out within Regulatory Guidance Note 3 (RGN3) — Groundwater Protection: Locational Aspects of Landfills in Planning Consultation Responses and Permitting Decisions, issued in December 2002. Before this the EA’s attitude to landfill location was set out within their policy and practice for the protection of groundwater (Groundwater Protection Policy), which stated that, with the exception of a few, all types of landfills could be developed within major and minor aquifers, as long as engineered containment and adequate operational safeguards were in place.

In practice, the nature of the containment, such as the lining system, and certain safeguards, for example, leachate control, were often defined by the results of a hydrogeological risk assessment that assessed the compliance of the site with the Groundwater Directive. This was the basis for Regulation 15 of the Waste Management Licensing Regulations, 1994, which dealt with landfill developments, and its primary requirement was that sites should not discharge List I substances to groundwater and that List II substances should be limited to avoid pollution. Substances are classified in terms of toxicity, persistence and bioaccumulation, with List I substances including cadmium, mercury and pesticides, while List II substances include ammonia and zinc.

As a result, many quarry operations located on major and minor aquifers were restored through landfilling with putrescible wastes, with containment measures and operational safeguards being designed on a risk basis and tailored to site-specific environmental circumstances. However, this tailored approach seems to be no longer possible for sites located on major aquifers and certain minor aquifers because of the EA’s interpretation of the requirements of the Landfill Regulations, 2002.

THE REGULATORY BASIS FOR THE LANDFILL LOCATION POLICY

Paragraph 1(1) of the Landfill Regulations requires that the geological and hydrogeological conditions of an area need to be considered when locating a landfill, while Regulation 5 states that a planning permission may only be granted for a landfill if the location issues in paragraph 1(1) have been taken into consideration.

Given that a Groundwater Protection Policy already exists and that risk-based hydrogeological assessments were already being carried out, it could be argued that these requirements were being complied with. However, the EA has taken the opportunity to adopt a significantly more stringent approach to landfill location, as set out within RGN3, bearing little resemblance to the actual requirements of the Landfill Regulations, 2002.

RGN3 REQUIREMENTS

RGN3 states that the EA will object to any proposed landfill located in Groundwater Source Protection Zone 1, which is an area in close proximity to a water supply source. This requirement is not considerably different from the original Groundwater Protection Policy. However, RGN3 also states that, where active long-term management is essential to prevent long-term groundwater pollution, the EA will object to sites that are:

  • below the water table in any geological strata where the groundwater provides an important
  • contribution to river flow or other sensitive surface waters
  • on or in a major aquifer
  • within source protection zones II or III (ie outside of zone I but within the catch-ment of a water supply).

While the second objection clearly refers to prohibition of landfills on major aquifers, the first and third could prevent landfilling operations on both major and minor aquifers.

These location restrictions are the main reason for not landfilling in areas that would have previously been thought appropriate. Few have directly challenged this interpretation of the Regulations. However, given the prohibitive nature of the requirements, it is widely viewed that now is the time to consider them in more detail.

The most restrictive and new aspects of RGN3 only relate to sites that require active long-term management to prevent long-term groundwater pollution. It is appropriate to consider what is meant by the terms ‘active management’ and ‘long term’.

‘Active management’

RGN3 states that ‘active management’ relates to the infrastructure, operation and maintenance necessary to mitigate risk, with specific reference to the collection, treatment and disposal of leachate. Passive measures relate to the lining systems, the presence of a geological barrier and any other mitigation processes that require no further intervention, for example, capping.

This suggests that landfills on major aquifers could be acceptable as long as all active measures, such as leachate management, are not carried out on a ‘long-term’ basis. Prior to the ‘long term’, the site needs to comply with the requirements of the Groundwater Directive without the benefit of active leachate management.

For this to happen, the options are:

  • For the site’s waste to be sufficiently stabilized before the ‘long term’ so that leachate levels can rise, being only controlled by the site cap preventing the infiltration of water, and the site remains in compliance with the Groundwater Regulations, 1998. Active recirculation and waste treatment could help with this process.
  • Developing the site with a sufficiently impermeable or thick containment to limit off-site migration of leachate from the site, following termination of active leachate control and the subsequent rise of leachate levels. The potential for such an option would be increased if the lining system or the unsaturated zone, whether natural or artificial, provided some attenuation capacity. In addition, leachate level rise could be limited by the installation of an impermeable cap during restoration.
  • Depending on the site design and configuration, it may be possible to passively drain leachate from the waste mass into a foul sewer or an adjacent existing site.
  • Ultimately, if active measures are required in the ‘long term’, one option would be to reduce the range of wastes disposed in the proposed landfill. For example, while disposal of putrescible domestic waste may not be possible, wastes, such as non-putrescible non-hazardous wastes, asbestos, and stable, non-reactive hazardous waste, would generate a leachate that would be sufficiently weak, allowing the relatively quick termination of active leachate management.

The ‘long term’

The EA has two broad interpretations of the phrase: the ‘long term’. One relates to the life cycle of the site while the other is based on a fixed period of time.

  • The life cycle of a landfill is the operational phase — when it is receiving waste, followed by closure when the void has been infilled. When closed, the site enters the aftercare period, during which a site operator must continue to manage the site in accordance with its PPC permit, until the site no longer requires active management and does not represent a risk to the environment. It is at this point that the permit can be surrendered.RGN3 assumes that the ‘long term’ lasts throughout the aftercare period and up until completion and surrender of the permit. Under this interpretation, a new non-hazardous landfill on a major aquifer would need to have stabilized or be managed using passive leachate management at the time of closure. This could be possible if a landfill is developed in line with some of the options discussed above.
  • Another interpretation of ‘long term’ is a 30-year period, based on the concept that, when considering the operation of landfills in the context of sustainable development, the EA accepted 30 years as a generally accepted time span beyond which the development may place a burden on future generations. This interpretation is not compatible with the life-cycle interpretation set out above. However, it provides operators with much greater flexibility as it allows a period of time following site closure when active management measures could take place. The implication is that a higher volume of putrescible waste could be disposed in the site or a lesser containment method could be used.

Clearly there needs to be some consensus reached on the definition of the ‘long term’. However, there is potential to develop new landfills on major aquifers under both interpretations.

CONCLUSION

The EA’s interpretation of the requirements of the Landfill Regulations, 2002, appear to prevent mineral operators landfilling as a means of restoration in a wide variety of potential sites. These interpretations bear no resemblance to the precise requirements of the Regulations and are a construct of the EA. In addition, they are unnecessarily prescriptive and ignore the previous risk-based approach that ensured landfill containment measures and operational safeguards were designed to suit local environmental circumstances.

However, it is considered that the EA’s current location requirements do not rule out the development of landfills on major and minor aquifers as long as they are appropriately designed and operated.

The author, Dr Alan Edwards, is director and hydrologist at SLR Consulting Ltd

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