Hazardous substances consent and HSE consultation zones

Hazardous substances consent is a separate consent from planning permission, granted under the Planning (Hazardous Substances) Act 1990 and administered through the Planning (Hazardous Substances) Regulations 2015. You need it where a hazardous substance is present at or above its controlled quantity, whether or not any building work is proposed, and holding planning permission for the use does not give it to you.

The related trap catches far more developers. Sites near an existing major hazard installation or a major accident hazard pipeline sit inside Health and Safety Executive consultation distances, and a housing scheme there can attract advice against the development without the applicant ever having heard of the installation.

What the consent covers

Consent attaches to the presence of a substance on land, not to a building or an operation. The hazardous substances authority is normally the local planning authority, and the application is made to it in a form set by the Regulations.

Three points follow that are easy to miss.

Consent runs with the land rather than with the operator. Under section 17 of the 1990 Act, a change in the person in control of part of the land revokes the consent unless a continuation application is made. That is a live issue on any site disposal or corporate restructuring involving part of a consented site.

Consent can be revoked or modified by the authority, with compensation consequences.

And a substance below its controlled quantity needs no consent, but aggregation rules mean several substances in the same hazard category can bring a site over the threshold together. Check the aggregation rule as well as the individual figure.

Controlled quantities and thresholds

Schedule 1 to the 2015 Regulations lists named substances and hazard categories with their controlled quantities. The categories follow the same structure as the major accident hazard regime, so a site already subject to those controls is usually within the consent regime too.

Do not work from a figure you remember. The schedule has been amended, substance classifications change with chemical regulation, and a quantity that was below the threshold five years ago may not be now. Read the current schedule and record the date you read it.

Common triggers on development sites include bulk liquefied petroleum gas storage, ammonium nitrate and similar fertiliser stores on agricultural holdings, chlorine at water treatment works, and fuel storage at depots and larger fleet operations. Agricultural and industrial clients frequently hold consent without realising it, or hold none when they should.

How consultation zones are drawn

Around each major hazard site and each major accident hazard pipeline, the Health and Safety Executive defines a consultation distance. Within it, the local planning authority must consult the Executive on planning applications for certain development.

The distance is divided into three zones: inner, middle and outer. The inner zone carries the highest individual risk and the outer the lowest. The zones are calculated from the substances present, their quantities, the containment and the site layout, so two apparently similar installations can generate very different distances.

Against those zones sits a sensitivity classification for the proposed development, based on the number of people present and their vulnerability. Workplaces and parking sit at the lowest sensitivity. Housing and smaller retail sit higher. Schools, hospitals and large retail higher again. Facilities for people least able to evacuate themselves, and large outdoor gatherings, sit at the top.

The advice comes from the intersection of the two. A warehouse in an outer zone raises no issue. A primary school in an inner zone will.

Reading the advice you receive

The Executive's response is advisory rather than determinative. It either advises against the development on safety grounds or it does not.

An authority is not bound to refuse where the Executive advises against, but the procedural consequence is significant. Under the Development Management Procedure Order, where the Executive has advised against and the authority proposes to grant permission, it must notify the Executive and hold the decision for a period, giving the Executive the opportunity to ask the Secretary of State to call the application in. A holding direction may follow.

In practice, an authority that grants against the advice carries the planning judgement alone, and few do so without a compelling reason. Plan on the basis that advice against means redesign rather than argument.

Get the position early. The site can be checked before acquisition, and the Executive's pre-application route lets an applicant test a proposal before committing to a layout. That check costs a fraction of a redesign.

Development near pipelines

Major accident hazard pipelines carry their own consultation distances, and they run through land that looks entirely ordinary. A high pressure gas transmission main crossing a field boundary is invisible unless you look for the markers or ask.

Two obligations arise. The consultation distance applies to development within the corridor, with the same zone and sensitivity logic. And the pipeline operator has to be consulted about works near the easement, which is a separate matter governed by the easement terms and the pipeline safety regime rather than by planning.

Build the check into site appraisal. A pipeline corridor that sterilises the developable part of a site is the kind of constraint that should affect the land price, and it is discovered easily at the outset and expensively at layout stage.

Responding to advice against

Where advice against is received, four responses are available, and they work better in combination.

1. Reduce the sensitivity of the development. Moving the most vulnerable use, such as a nursery or a care element, out of the inner zone can change the outcome while leaving the scheme viable.
2. Change the layout. The zones are geographic, so relocating built form and concentrating open space, parking or landscaping within the higher risk zone is often decisive.
3. Reduce numbers. Sensitivity classifications turn partly on occupancy, so a smaller scheme may fall into a lower band.
4. Engage with the operator. Where the installation's inventory has fallen, a revised consent or an updated assessment may reduce the consultation distance itself. That is slow, and it occasionally works.

Record whichever route you take in the Planning Statement, with the correspondence appended. Officers need to show they considered the advice and explain the conclusion.

Recording the position in the application

For any site within a consultation distance, include a short section covering five points: the installation or pipeline concerned, the zone the site falls within, the sensitivity classification assumed for the proposed development, the advice received and its date, and the design response.

Where the proposal is itself an installation handling hazardous substances, the application for consent runs alongside the planning application and the two should be submitted together. Larger installations may also fall within the environmental impact assessment regime, and an Environmental Impact Assessment for such a scheme must be prepared by competent experts under the 2017 Regulations, with a PlanScope draft being a starting point for that expert rather than a substitute.

Fire safety is a related but distinct question. A Fire Statement is required at Planning Gateway One for relevant buildings under the Building Safety Act framework and must be prepared by someone with the necessary fire engineering competence. It does not address major accident hazards, and neither regime substitutes for the other.

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

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