Treagus, R (on the application of) v Suffolk County Council & Anor

In deciding whether development is likely to have significant environmental effects, a planning authority may take proposed mitigation into account. The authority must make a lawful planning judgment based on the available information, including reliable expert advice. An environmental impact assessment is not automatically required because mitigation involves prediction or because some details remain to be finalised. A policy error may nevertheless justify refusing judicial review relief where the alleged risk is unsupported, the issue received proportionate consideration, the policy has ceased to apply, and relief would serve no practical purpose. A planning condition may be severed where its unlawful wording is distinct and does not permit a change to a key element of the permitted development.

The claimant sought judicial review of Suffolk County Council’s grant of planning permission for an anaerobic digestion plant. She challenged the environmental impact assessment screening decision, the failure to require a bio-aerosol risk assessment, and a condition permitting variation of the geographical source of feedstock. The Council had concluded that mitigation measures, including the design and construction of an underground slurry tank, meant that significant environmental effects were unlikely. The central issues were whether that conclusion was lawful, whether the Council had unlawfully applied its former bio-aerosol policy, and whether the disputed wording of the feedstock condition could stand.

1. Ground 1. The Council lawfully concluded that the plant was not likely to have significant environmental effects. The screening assessment was an exercise of judgment. The Council was entitled to take account of proposed remedial measures and to rely on the Environment Agency’s expert advice that appropriate design and Best Available Techniques would prevent significant groundwater and surface-water impacts. It was not necessary for every design detail to have been finalised. The circumstances were materially different from Gillespie v First Secretary of State and Bellway Urban Renewal Southern Limited [2003] 2 P & CR 236, and the approach in R(Catt) v Brighton and Hove City Council [2007] LGR 331 supported the Council’s assessment.
2. Ground 2. The Council erred in treating occupiers of premises on the interested party’s land differently from other nearby occupiers when considering the former Suffolk Waste Local Plan policy requiring a bio-aerosol risk assessment. The policy did not distinguish between employees, tenants and other residents. Generic duties under the Health and Safety at Work Act 1974 were insufficient justification for that distinction. Relief was nevertheless refused. The evidence did not establish a real bio-aerosol risk, the issue had received proportionate consideration and advice, the policy was no longer extant when permission was granted, and relief would have been otiose.
3. Ground 5. The words permitting the Waste Planning Authority to approve a departure from the 30-mile feedstock limit were severable. Unlike R(Midcounties Co-operative Ltd) v Wyre Forest District Council [2009] EWHC 964 (Admin), the condition did not permit alteration of a key element of the development. It was closer to R (Salford Estates (No 2) Ltd) v Salford City Council [2011] EWHC 2097 (Admin). The offending words were therefore severed, and relief was granted to that limited extent.

The judgment records earlier permission proceedings and an unsuccessful appeal to the Court of Appeal, but gives no citation for those decisions.