The landfill was for non-hazardous household, commercial and industrial waste, and excluded hazardous waste unless it was stable and non-reactive, with the total amount restricted to 5.2 million cubic metres.
Part of the site was below the water table, and it was this aspect that formed the key grounds of legal challenge. The site was to be operated by means of a hydraulic containment system by which the level of leachate in the landfill was maintained at a lower level than the surrounding external groundwater. The pressures maintained by pumping were designed to ensure that any leakage that might occur would be into the site rather than outwards.
Although the applicant suggested that sub-water table landfilling was unusual, the Agency maintained that this happened at around a third of existing non-hazardous landfills in England and Wales, and more frequently in areas such as the Midlands and East Anglia.
Nevertheless, the claimant argued that granting a licence for such a landfill was contrary to both the 1999 landfill Directive and the 1980 groundwater Directive. It was accepted that the Directives had been correctly transposed into national law, and Mr Justice Sullivan decided simply to refer to the Directives themselves - a striking example of the extent to which the provisions of EU environmental law are accepted in the British courts.
Dealing with the landfill Directive, the claimant pointed to one of the general requirements in Annex I to "prevent surface water and/or groundwater from entering into the landfilled waste". It was argued that the hydraulic gradient system to be employed in the landfill did not prevent groundwater from entering the landfill but actually allowed it do so albeit at a gradual rate in order to prevent leachate from seeping through the clay liner in the opposite direction.
The Agency acknowledged that the clay lining was not totally impermeable, and, according to the claimant, the only way to "prevent" the entry of groundwater was to locate the landfill above the water table.
Mr Justice Sullivan warned against lifting individual provisions of the annex out of context, and held that one had to start by looking at the Directive's overall objectives, which were in essence to allow only controlled landfill activities to prevent or reduce negative effects on the environment.
Annex I, he said, was not designed to prohibit large scale landfilling but to allow authorisation only where they posed no environmental risks. In that context, the use of clay liners as here would prevent groundwater from entering the site.
No material was totally impermeable, but Mr Justice Sullivan felt that the term "prevent" in this context could not mean to actually make impossible or stop, but implied to "stop to the extent that it is possible to do so using engineering techniques" such as those described in Annex I: "When they agreed to the Directive, the Member States would have been well aware of the fact that, since no material is totally impermeable to water, it would be an engineering impossibility completely to prevent (or "stop" the sense in which "prevent" is used by the claimant) groundwater from entering into a landfill if any part of it was below the water table."
If the intention of the Directive had been to ban sub-water table landfills, one would, according to the court, have expected to see some express reference to this on the face of the Directive.
The claimant also relied upon provisions of the groundwater Directive which included a prohibition on direct discharges of List I substances into groundwater.
A direct discharge is defined in the Directive to mean "the introduction into the groundwater of substances in List I without percolation through the ground or sub-soil", and it was accepted that the landfill leachate would contain List I substances.
The claimant argued the slow percolation of groundwater through the clay liner into the leachate resulted in direct contact between the leachate and the groundwater, and was therefore contrary to the Directive's prohibition.
Mr Justice Sullivan held that this interpretation "stands the Directive on its head." The Directive was concerned with preventing the discharge of pollutants into groundwater which here would be achieved by the clay liner coupled with the hydraulic gradient that ensured that any percolation was into the landfill and not the other way around.
The claimant argued that there was no real difference between introducing groundwater into leachate, as here, and introducing leachate into groundwater. But Mr Justice Sullivan considered there was a fundamental distinction: "While the chemical composition of the resulting liquid might be the same, in the former example the polluted liquid will be contained within the clay liner, where it would be collected and treated to an appropriate standard; in the latter it would be free to pollute the surrounding groundwater, contrary to the underlying purposes of the Directive."
In any event, he felt that once any water had entered the clay lining, it could no longer be described as "groundwater" since it was no longer in direct contact with the ground or sub-soil. The geological barrier created by the landfill, albeit consisting of clay, could not be described as part of the ground or sub-soil.
The prevention of the outward movement of the leachate was to be achieved by means of pumping to keep the level of leachate below the water table. This was a technical precaution, and the claimant argued that, in the case of direct discharges, the groundwater Directive contained an absolute prohibition and did not permit the use of technical precautions to prevent such discharges.
Again, Mr Justice Sullivan felt that such an interpretation did not sit easily with an underlying purpose of the Directive which required Member States to "take the necessary steps" to prevent the direct and indirect discharge of List I substances into groundwater.
"In order to achieve this objective, I can see no practical difference between prohibiting a direct discharge and requiring the observance of all the technical precautions that are necessary to prevent it." According to technical evidence, even a failure of the pumping system would mean that no discharge to groundwater of any List I substances present in the leachate would occur for many months, during which period the necessary remedial steps could be taken.
The claimant's final main argument concerned the financial security provided by Onyx, which was claimed to be contrary to the general requirements in Article 8 of the landfill Directive.
The Agency had assessed the costs likely to be incurred for a period of 60 years post-closure, and had then provided for the establishment of a contingency fund for periods beyond that. A performance agreement and bonded sum had been provided in the event of insolvency by the company.
The claimant argued that since the pumping might have to continue well beyond 60 years after closure of the site, the Agency had failed to ensure that Onyx made adequate financial provision for post-closure responsibilities as required by the Directive.
It was not suggested that the residual contingency sum was necessarily inadequate for the purpose of the post-60-year period, and given what he described as "an air of unreality in this ground of challenge", Mr Justice Sullivan rejected the argument.
Mr Justice Sullivan did not feel that any reference to the European Court of Justice was needed, especially given the long delays that had already occurred, although an appeal may still be made. The underlying tenor of the judgement is to reject a semantic approach to the interpretation of the legislative requirements but to set them against practical realities and their underlying policy purpose.
Richard Macrory, Professor of Environmental Law, University College, London