Impact assessment: Guiding light

3rd April 2020

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Andy Ricketts explains the importance of IEMA guidance in avoiding legal challenges relating to EIA

The IEMA Impact Assessment Steering Group has discussed the implications of several legal cases for EIA practice, specifically the use of mitigation in EIA. The current EIA regulations and national guidance support the role of mitigation in determining whether a project comprises EIA development, and define the need for mitigation to be adequately described. IEMA has produced guidance on the use of mitigation and necessary control mechanisms in its EIA Guide to: Delivering Quality Development (

If mitigation is identified at any stage of the EIA process, it must be specific and fully evaluated to ensure there is confidence in its effectiveness. There is also a need for clear control measures to ensure that mitigation identified (in some cases at the EIA screening stage only) is successfully implemented to avoid, reduce or offset environmental impacts.

Legal cases

The need for specific, effective mitigation was considered in Kenyon R v Wakefield Council & Ors, 18 December 2018. In this case, a decision had been made that the redevelopment of a disused sports complex was not EIA development, due in part to the reliance on future ground investigations and remediation (secured by condition). While the case was dismissed, it (a) strengthened the role of mitigation in determining whether a project comprises EIA development; (b) confirmed the importance of developing evidence (both specific and implementable) to allow a reasoned conclusion on the need for EIA; and (c) showed that without specific, effective mitigation, there could be 'material doubt' and in this scenario any decision should be 'in favour of EIA'.

“Mitigation must be specific and fully evaluated to ensure there is confidence in its effectiveness“

Squire R v Shropshire Council, 24 May 2019, further considered the application of mitigation. The challenge made was that effects of the odour and dust associated with the proposed disposal of manure from a chicken farming facility had not been sufficiently considered and assessed. The Environmental Statement (ES) supporting the planning application relied on the application of the Environmental Permitting (England and Wales) Regulations 2016 to control and manage environmental impact from the disposal of manure. It was concluded that the ES was legally deficient, and planning permission was quashed.

However, the failure of the ES in this case was that the 'expected residues' – the manure – and its disposal off-site had not been defined as part of the description of development as required under Schedule 4 of the EIA Regulations. If this had been completed, the ES would have duly considered the indirect effects of the project as a whole. This case has brought into question the use of other existing legislative requirements as mitigation, which is promoted by IEMA guidance. They should still be used; however, their application to avoid, reduce or offset environmental impacts requires careful evaluation and the role and function of the legislation (and regulators) needs to be clearly defined alongside the control mechanisms for its effective implementation.

The application of mitigation in EIA is likely to continue to be a topic for legal debate, but the pitfalls and associated delays and costs can be avoided through the use of IEMA guidance. Application of the guidance can also assist with robustly reducing the scope or need for EIA.

Andy Ricketts is head of EIA at Turley


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