Hazardous installation consultation distances and housing

If your site sits inside the consultation distance of a major hazard installation, the council has to consult the Health and Safety Executive before deciding the application, and the answer comes back as either advise against or do not advise against. There is no middle setting and there is no negotiation over glazing specification. The advice turns on how many people would be present, how vulnerable they are, and how close to the installation they would be, so the only real lever a developer has is the layout and the mix.

Find out the distance before you buy. An advise against response on a residential scheme is very hard to recover from.

Why some industrial sites carry a consultation distance

Sites holding quantities of dangerous substances above thresholds in the Control of Major Accident Hazards Regulations 2015 are notified establishments, and the same applies to licensed explosives sites and to certain pipelines. Around each one, a consultation distance is set by the regulator based on the substances held, the quantities and the containment.

Typical installations are chlorine storage at a water treatment works, bulk liquefied petroleum gas depots, ammonia refrigeration at large cold stores, chemical works, fuel terminals, and gas holders and pressure reduction stations. Many of them look unremarkable from the road, which is how developers end up surprised.

The distance is not a buffer in the planning policy sense. It is a trigger for consultation, and the outcome inside it depends entirely on what is proposed.

The Development Management Procedure Order 2015 puts the Health and Safety Executive on the list of statutory consultees for development within a consultation distance, so the consultation happens whether or not anyone flags it. Councils hold the distances on their constraints layers, and the regulator publishes a service that returns the position for a given site.

The inner, middle and outer zone approach

Within the consultation distance the regulator works with three zones, an inner, a middle and an outer, reflecting decreasing risk with distance from the installation. The zones are specific to each site rather than a standard set of radii.

The same proposal gets a different answer in each zone. Housing in the outer zone will often attract a do not advise against response, the same housing in the inner zone will usually attract advise against, and the middle zone is where scheme design decides it.

Part of a site inside the inner zone does not doom the whole site. Where the red line spans two zones, the workable answer is often to place car parking, landscaping, attenuation or employment floorspace in the nearer zone and residential in the further one.

How the sensitivity of the proposed use is scored

The regulator's methodology sorts proposed development into sensitivity levels rather than into planning use classes. In broad terms, level one covers workplaces and parking with limited numbers of people, level two covers development occupied by the general public in numbers, including housing and most retail, level three covers development occupied by people less able to protect themselves, such as schools, nurseries, hospitals and care homes, and level four covers very large public assemblies and outdoor uses.

Two features of that scheme matter to a developer. The level rises with vulnerability rather than with floorspace alone, so a nursery of 40 children can attract a harder answer than a 200 space office. And the numbers of people, not the number of units, drive the result, so a scheme of small flats with high occupancy can score worse than expected.

Care homes, sheltered housing and extra care schemes sit at the top of the scale and are the proposals most often advised against. Student accommodation and hotels sit awkwardly, and the answer depends on the specific case, so ask rather than assume.

The weight the regulator's advice carries

The advice is not a veto. It is advice to the local planning authority, which remains the decision maker, and councils have granted permission against it.

In practice it behaves like a veto on most residential schemes. The advice goes on the file, objectors cite it, and a council granting permission against it faces a procedure requiring the regulator to be notified, with the possibility that the application is called in. Few officers will recommend approval against advise against without a very strong planning case behind it.

So treat the advice as the determinative technical input and design to avoid it, rather than planning to argue with it. Where an advise against response has already been given, the productive routes are a revised layout, a change of mix, or a reduction in the sensitivity of the nearest uses.

Designing a scheme to reduce the population at risk

The methodology is about the presence of people, which points the design in a specific direction:

1. Put the least sensitive uses closest to the installation. Parking, open space, attenuation basins, substations and employment floorspace all belong at that end of the site.
2. Reduce occupancy near the installation. Lower density, fewer bedrooms per unit, and no vulnerable uses in that part of the layout.
3. Avoid outdoor assembly close to the boundary. A play space or a school field near the installation can be worse than a building.
4. Do not rely on construction mitigation. Blast resistant glazing, protected facades and shelter arrangements do not generally change the regulator's assessment, because the methodology deals with risk to people rather than with mitigation measures.
5. Check the whole red line, including access roads and any phasing that would bring people onto the nearer part of the site temporarily.

That fourth point is the one designers resist and it saves the most wasted effort. A facade specification will not turn advise against into do not advise against.

Where the constraint runs alongside other route based or linear designations on the same site, the analysis is similar, and safeguarded transport routes and what you can build shows how those are handled.

Hazardous substances consent as a separate regime

Two different consent systems sit around the same installations and they are regularly confused.

Hazardous substances consent is needed by the operator to hold specified substances above controlled quantities at a site. It is granted by the hazardous substances authority, usually the local planning authority, and it is separate from planning permission. A developer proposing housing nearby has nothing to apply for under that regime.

What matters to the developer is the reverse position. Where an existing installation holds consent, that consent is a material consideration, and the operator may object to nearby development because encroachment can constrain its own future operations. Operators do object, and their objections are taken seriously because they carry real evidence about the substances involved.

If the installation is expected to close or reduce its inventory, the consultation distance changes only when the consent and the notified quantities change. A verbal assurance from a site manager that the chlorine is going is not evidence. Get the position in writing from the operator and check with the regulator.

What to submit and who to ask first

Do this in order. Establish whether the site is within a consultation distance, and if it is, which zone each part of the site falls in. Ask the regulator through its planning advice service and ask the council for its constraints layer, because the two should agree and occasionally do not.

Then talk to the case officer before designing. A pre-application discussion that establishes the council's approach to the zones is worth more than any amount of drawing.

The application itself needs a plan showing the installation, the consultation distance and the zone boundaries against the proposed layout, a schedule of the proposed uses and the expected number of people in each part of the site, and a short section in the Planning Statement explaining how the layout responds. Where the scheme includes any use occupied by people less able to protect themselves, say so explicitly rather than leaving the officer to work it out from the drawings.

Add the constraint to the due diligence checklist for every site near industry, alongside everything else covered in checking a site for constraints before you make an offer. The cost of asking is a few days. The cost of not asking is a scheme that cannot be built.

You can draft the planning statement and the supporting documents for a constrained site in PlanScope and send them for professional review before submission. Browse all 66 report types at the PlanScope report index.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.