Hazardous substances consent: applying, varying and keeping it
Hazardous substances consent is a separate permission triggered by the quantity of a listed substance on site. Here is how the application works, and the change-of-control rule that quietly revokes consents.
You need hazardous substances consent when a listed substance is, or will be, present on land at or above its controlled quantity. Consent is a separate permission from planning permission, granted under the Planning (Hazardous Substances) Act 1990 and the Planning (Hazardous Substances) Regulations 2015. A hazardous substances consent application goes to the hazardous substances authority for the area, which is usually the same council that determines your planning applications, and it is assessed on the risk that the presence of the substance poses to people and to the surrounding area.
Most businesses meet this regime by accident. A cold store adds an ammonia plant, a farm shop starts bulk storing liquefied petroleum gas, a laboratory scales up a solvent, and the quantity on site quietly crosses a threshold that nobody was tracking.
When consent is needed at all
The trigger is presence, not use. If the substance is on the land at or above the controlled quantity at any point, consent is required, and that includes material held in tanks, in drums, in transit within the site and in process vessels.
Presence is assessed across the whole of the land under one person's control, not per tank or per building. Two 1.5 tonne LPG tanks at opposite ends of a yard are 3 tonnes for these purposes.
There are exemptions. Substances in transit through the site, material at licensed waste sites in some circumstances, and certain quantities held temporarily are treated differently, and the detail sits in the 2015 Regulations rather than in guidance. Read the exemption before you rely on it, because the wording is narrow.
Consent is also needed before you increase an existing lawful quantity beyond what an earlier consent allows. Deemed consents granted when the regime changed carry their own limits, and those limits are frequently lower than what a modern operation wants to hold.
Controlled quantities and the addition rule
Schedule 1 to the 2015 Regulations lists named substances and generic categories with a controlled quantity for each. The categories follow the same hazard classes used for major accident control, so a site already inside the COMAH regime will recognise the language.
Where several substances in the same hazard category are present below their individual thresholds, the addition rule can still bring the site into consent. You divide the quantity of each substance by its controlled quantity, add the fractions, and if the total reaches one, consent is required for that category.
| Situation | Consent needed |
|---|---|
| One named substance at or above its controlled quantity | Yes |
| Several substances, each below threshold, fractions summing to one or more in a category | Yes |
| Substance present only in transit and not unloaded | Check the exemption wording |
| Quantity increased above an existing consent | Yes, a fresh application |
Work the addition rule with the maximum quantity the site can physically hold, not the average stock level. Councils and the safety regulator both test the ceiling, and an application built on typical throughput tends to come back with questions about tank capacity.
Who you apply to
For most sites the hazardous substances authority is the district, borough or unitary council. National Park authorities act as the authority within their areas, and there are special arrangements where the land is operational land of statutory undertakers or where the proposal sits alongside county matters such as minerals and waste.
Ring the council first and ask which team handles it. Hazardous substances consent sits awkwardly between planning and environmental health in many authorities, and a misdirected application can sit unregistered for weeks.
The fee is set nationally and is paid to the authority with the application. Where a planning application for the same development runs in parallel, the two are determined separately, and one can be granted without the other.
What goes in the application
The form asks for the substances, the maximum quantities, the manner in which each will be kept, and a site plan showing where on the land each substance will be. A plan that shows only a red line will not validate.
- Complete the prescribed form with substance names, hazard categories and maximum quantities.
- Provide a substance location plan at a readable scale, marked with tanks, vessels, stores and bunding.
- Serve notice on any other owner of the land and complete the ownership certificate.
- Publicise the application as required, including a site notice and a newspaper advertisement.
- Pay the fee and submit.
A short supporting statement helps, even though it is not a validation requirement. Set out what the operation does, why the substance is held, how it is contained, and what separation exists between the storage and the site boundary. If you are already preparing a Planning Statement for a related planning application, keep the two documents consistent on quantities, because inconsistent figures are the fastest way to lose the safety regulator's confidence.
Consultation with the safety regulator
The authority consults the Health and Safety Executive, and in practice the HSE's advice decides the outcome. The advice considers the population around the site, the nature of the substance, and the consequences of a credible major accident.
The Environment Agency is consulted where the substance presents a risk to controlled waters or where an environmental permit interacts with the proposal. Neighbouring authorities are consulted where the risk crosses a boundary.
Consent brings a lasting consequence that surprises operators. Once consent is granted, the HSE sets consultation distances around the site, and the local planning authority must then consult the HSE on new development proposed within those distances. Housing schemes, schools and retail units near your boundary will be assessed against your consent for as long as it lasts.
The authority is expected to decide within eight weeks unless a longer period is agreed. Complex applications routinely need an extension, and agreeing one in writing is better than letting the period lapse and losing the ability to negotiate.
Conditions, variation and revocation
Consent can be granted subject to conditions covering how the substance is kept, the maximum quantity, the location of storage and the containment provided. Those conditions are enforceable, and contravention is an offence rather than a matter for the ordinary planning enforcement route that a planning contravention notice would start.
To change a quantity, a location or a condition you apply to the authority again. Small operational changes sometimes fit within the existing consent, but the test is what the consent and its plan actually permit, not what feels equivalent.
The authority can revoke or modify a consent, including where the substance has not been present for at least five years, where there has been a material change of use of the land, or where planning permission has been granted for development that would be incompatible. Compensation is payable in defined circumstances, and the procedure for revocation gives the consent holder a right to be heard.
Unlike a planning permission, a hazardous substances consent does not expire on a timetable. It is not a temporary permission that lapses after a set period, and that permanence is exactly why authorities attach tight conditions at the outset.
Change of control of the land
This is the provision that catches buyers and their solicitors. Where a person becomes entitled to an interest that gives control of the land, or of part of it, the consent is revoked unless an application for continuation of the consent is made to the authority within six months.
So a site sale, a corporate restructure that moves the freehold, or the grant of a lease over part of a yard can all extinguish a consent that the business depends on. The continuation application is straightforward and the authority may grant it subject to the same or different conditions. Missing the six month window means starting again, with fresh publicity and fresh consultation, and with no guarantee that the safety regulator's view will be what it was ten years ago.
Add the check to the acquisition checklist alongside environmental permits. Ask the seller for the consent, the approved substance plan and every subsequent variation, and compare the permitted quantities against what is actually standing in the yard.
Enter your postcode on PlanScope to see which supporting reports your site is likely to need, or browse all 66 report types if you already know the shape of the application. Start from the home page if you want the site checked against flood, heritage and ecology data first.
This is general guidance rather than legal advice. Check the position with your 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.
Frequently asked questions
Is hazardous substances consent the same as planning permission?
No. It is a separate consent granted under the Planning (Hazardous Substances) Act 1990 and the 2015 Regulations, and it is determined by the hazardous substances authority rather than through the ordinary planning application route. You can hold one without the other. Where a development needs both, apply in parallel and keep the quantities and site plans identical across the two submissions.
How long does a hazardous substances consent application take?
The authority is expected to decide within eight weeks of a valid application unless a longer period is agreed in writing. Consultation with the Health and Safety Executive drives the timetable, so complex or unusual substances often need an extension. Agree any extension formally rather than allowing the statutory period to expire without a decision.
What is the addition rule for controlled quantities?
Where several substances in the same hazard category are held, you divide each quantity by its own controlled quantity and add the resulting fractions. If the total reaches one, consent is required for that category even though no single substance has reached its threshold. Calculate it on maximum storage capacity rather than on average stock held.
Does selling the site affect an existing consent?
Yes. Where a person becomes entitled to an interest giving control of the land or part of it, the consent is revoked unless an application for continuation is made to the authority within six months. This catches share transfers, freehold sales and leases over part of a yard. Put the check into the acquisition process alongside environmental permits.
Can conditions on a consent be changed later?
Yes, by applying to the hazardous substances authority again. There is no shortcut equivalent to a non-material amendment, so a change in quantity, storage location or containment usually means a fresh application and fresh consultation with the safety regulator. Check whether the change falls outside what the existing consent and its approved plan already permit.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.