Unicoin (Dartford) Ltd, R (on the application of) v Secretary of State for Communities and Local Government & Anor

In a challenge under Town and Country Planning Act 1990, the court held that guidance for deciding hazardous substances consent applications could not be read across to planning applications for development near an existing hazardous installation. The decision-maker was not required to apply a separate tolerability-of-risk test.

Where an existing hazardous substances consent is expressed in broad or generic terms, a risk assessment based on exemplar substances representing the consented risk envelope may be lawful. The decision-maker may weigh that assessment against more specific information from a COMAH notification. The adequacy and rationality of that assessment are matters for the decision-maker, provided the relevant evidence and controls are considered and adequate reasons are given.

The claimant sought under section 288 of the Town and Country Planning Act 1990 to quash an Inspector’s decision dismissing its appeal against refusal of planning permission for 96 dwellings at a former effluent treatment works in Dartford.

The site lay partly within the inner consultation zone of a neighbouring hazardous installation. The Inspector relied on HSE advice based on the maximum quantities permitted by broad hazardous substances consents and exemplar substances. The claimant argued that the assessment should instead use the specific substances identified in a COMAH notification, and that the Inspector had to decide whether the residual risk was tolerable. The central issues were whether the Inspector had applied the correct policy approach and whether her reasoning was irrational or inadequate.

1. The application was dismissed. The claimant was ordered to pay the first defendant’s costs, summarily assessed at £10,520. Permission to appeal was refused, although time to apply to the Court of Appeal was extended until 14 days after release of the approved transcript.
2. Paragraph 41 of Circular 04/00 concerned applications for hazardous substances consent. It did not require an Inspector determining a planning application for development near an existing hazardous installation to apply a tolerability-of-risk test. The court would not fill an alleged policy gap by extending that test to a different statutory context or usurp the Secretary of State’s policy-making function.
3. The Inspector was entitled to assess the implications of broad hazardous substances consents by reference to an envelope of risk represented by exemplar substances. Paragraph 37 of the Circular dealt with applications for hazardous substances consent and did not require the use of specific substances identified in a COMAH notification when assessing an existing consent’s implications for a planning proposal.
4. The Inspector had considered the claimant’s alternative evidence based on the 2000 Regulation 6 notification. It was for her to decide the weight to attach to that evidence and to HSE’s assessment. Her conclusions about inconsistencies in the notification and the scope of the consent disclosed no material error.
5. The COMAH controls focused on preventing major accidents and limiting their consequences. They did not control every change in substances stored or used under an existing consent, revoke or modify that consent, or eliminate residual risk. The Inspector therefore acted lawfully in giving those controls, and the lower risk shown by the specific notification, little weight.
6. The Inspector was entitled to conclude that a significant increase in the number of people exposed to residual risk within the inner zone was objectionable. The fact that existing residents faced a tolerable risk did not require the proposed additional dwellings to be accepted. The application of the PADHI criterion was not irrational on the evidence before her.