The extent to which mitigation measures may be taken into account when screening for EIA development
Where a local planning authority (“LPA”) concludes that development proposals fall within Schedule 2 to the Town and Country Planning (Environmental Impact Assessment) Regulations 2011, it must the decide whether the development is likely to have significant effects on the environment by virtue of factors such as its nature, size or location. If it is so likely, then the development is an EIA development, and the developer will be required to submit an environmental statement (“ES”). One purpose of the ES is to set out “a description of the measures envisaged to prevent, reduce and where possible offset any significant adverse effects on the environment”.
However, the question from time to time arises whether an LPA may – at the stage of deciding whether the development is an EIA development – take such measures into account. Earlier authorities establish these principles: The LPA can have regard to the mitigating measures provided that they are sufficiently specific, they are available and there is no real doubt about their effectiveness. However, the more sophisticated the mitigating measures and the more controversy there is about their efficacy, the more difficult it will be for the LPA to reach a decision that the environmental effects of the development are not likely to be significant.
In R (on the application of Treagus) v Suffolk County Council [2013] EWHC 950 (Admin), the claimant sought to quash a decision by the LPA to grant planning permission for an anaerobic digestion plant, one part of which comprised a sealed underground slurry tank. Her principal ground of challenge was that the negative screening opinion adopted beforehand by the LPA was wrong in law because it relied upon mitigation measures relating to the risk of groundwater pollution from the slurry tank. (The site lay over a major acquifer used for public drinking water abstractions.)
The court dismissed the claim. In essence, the LPA had to decide whether the slurry tank would be designed in such a way that it meant that it was not likely to leak. That was a matter for its judgment, a judgment that was to be formed in the light of the information available to it, including expert advice received from the EA. It had lawfully concluded that the development was not an EIA development. To act as it did was not Wednesbury unreasonable or otherwise unlawful.
John Martin
