No chances to be taken with suffocating gas

It is often argued that conditions are unnecessary where the matter of concern is also addressed by other legislation but in the following case the inspector decided to take a belt and braces approach.

The inspector declined to delete a condition attached to the planning permission for a bus depot in Northumberland (DCS Number 400-009-827) which required a scheme to protect the buildings from the ingress of gas from former mine workings, finding that it was reasonable and necessary.

The council was particularly concerned about the risk from stythe gas, an asphyxiant which reduces the available oxygen content of air to a level incapable of sustaining human life.

The appellant argued that the condition was not necessary or relevant to planning, because ingress of gas from former mine workings was controlled under building regulations, and additionally by environmental health legislation. He also regarded this overlap of controls to make the condition unreasonable and to place an unnecessary burden on him.

The inspector noted, however, that Paragraph 121 of the NPPF states that planning decisions should ensure that the site is suitable for its new use taking account of ground conditions and land instability including from natural hazards or former activities such as mining. In this regard she had seen no evidence to demonstrate which controls outside planning legislation would provide a suitable alternative means of managing the matter.

The appellant had undertaken an investigation comprising ground investigation, geotechnical testing and chemical analysis supplemented by further monitoring of soil gases and groundwater. Results from the investigation showed that detected oxygen levels dipped to 14.7 per cent in one instance whereas typical atmospheric levels are around 21 per cent. The Mines Regulations 2014 contain a requirement to ensure that the amount of oxygen below ground is no less than 19 per cent volume, the inspector recorded. These seek to protect the workforce from harm, but relate to mine workers, rather than the occupiers of buildings.

The inspector concluded that in practical terms the recorded oxygen level of 14.7 per cent fell well below the level normally found in the atmosphere, and also below the level required for mine workers. Whilst appreciating that the occupants of the depot would not be working underground, she reasoned that the development nevertheless involved building enclosed spaces including sunken inspection pits and ground floor offices on top of land where mine gas might be present. She decided that since the occupiers of the depot were not adequately protected against the effects of stythe gas, and bearing in mind that there had been a number of near misses and one fatality in Northumberland relating to mine gas accumulations, the adverse impacts arising from a lack of suitable protection could be significant.

It remained necessary and reasonable to require the submission of a scheme to protect the buildings from the ingress of gas from former mine workings, particularly stythe gas, the inspector ruled.

The interesting point of debate raised by this decision concerns the necessity of conditions and the point at which a sensible safety first approach becomes the duplication of controls. Other similar types of condition come to mind, say drainage conditions, but readers will no doubt be able to think of other examples. Is there scope for the introduction of some clarity about what the rules are here?

The following DCP chapter is relevant: 4.417

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