Hazardous substances consent and the threshold quantities
Consent is needed before a listed substance is present at or above its controlled quantity. It runs with the land, the aggregation rules catch small holdings, and planning permission says nothing about it.
Hazardous substances consent is a separate consent from planning permission, and you need it before a listed hazardous substance is present on land at or above its controlled quantity. The substances and their controlled quantities are listed in a schedule to the Planning (Hazardous Substances) Regulations 2015, and the consent runs with the land rather than with the business. A takeaway storing bulk liquefied petroleum gas, a swimming pool with a chlorine installation, a cold store using ammonia and a fuel depot can all cross a threshold that most occupiers have never heard of.
Having the substance on site without consent is an offence, and planning permission for the building says nothing about it.
What the consent controls
The regime controls the presence of a hazardous substance on, over or under land at or above the controlled quantity for that substance. It is about presence, not about process safety, which is dealt with separately by health and safety and environmental legislation.
The point of the regime is land use. Consent gives the authority a chance to consider whether a quantity of a dangerous substance should be present in that location, given what is around it, and to attach conditions about where and how it is kept. It does not duplicate the safety case.
Three separate regimes can apply to the same installation. Hazardous substances consent, under the planning legislation. The major accident hazards regime, where the inventory crosses its own lower or upper tier thresholds. And an environmental permit where the activity requires one. Crossing one threshold does not tell you whether you have crossed the others.
Threshold quantities and the substance list
The schedule names substances individually, such as chlorine, ammonia, liquefied petroleum gas and certain explosives, and also defines categories by hazard classification. Each entry carries a controlled quantity in tonnes.
Two mechanical rules catch people out:
- Aggregation. Quantities of the same substance across the site are added together, and substances within the same hazard category are brought together under a summation rule, so several below threshold holdings can produce a consent requirement.
- The small quantity disregard. A quantity present at a part of the site at or below a stated small proportion of the controlled quantity can be left out of the calculation where it could not act as an initiator elsewhere on the site. This is narrower than it first appears.
Work from the safety data sheets, take the hazard classifications from them, and check the schedule entry for both the named substance and any category it falls within. Where the inventory is close to a threshold, record the maximum quantity that could be present rather than the usual holding, because the consent has to cover the maximum.
Who the hazardous substances authority is
For most sites the hazardous substances authority is the local planning authority, which in practice means the district or unitary council. There are exceptions, and they matter because an application to the wrong body wastes weeks.
| Situation | Authority in general terms |
|---|---|
| Ordinary land in a district or unitary area | The district or unitary council |
| Land in a National Park | The National Park authority |
| Operational land of certain statutory undertakers | The body specified in the legislation for that undertaking |
| Land covered by a development corporation or urban regeneration body | That body where it has been given the function |
Check the current position in the Act and the Regulations rather than assuming, and ask the council's planning department who holds the function if there is any doubt.
What an application must include
The application is made on a prescribed form with a fee set by the Regulations, and it needs more technical detail than a planning application of similar size.
- The substance or substances by name and hazard classification, with the safety data sheets.
- The maximum quantity of each that will be present, and the basis of that figure.
- How it will be kept: vessel types, capacities, pressures, temperatures, bunding and location.
- A site plan showing the position of each vessel or store, with distances to the site boundary and to buildings on and off site.
- A description of the process or use the substance supports.
- Details of the surrounding area, including nearby dwellings, schools, hospitals and other sensitive uses.
- Notice served on owners and agricultural tenants where the applicant does not own the whole of the land, with the relevant certificate completed.
Get the plan right. The authority and its consultee are assessing distances, so a plan without a scale bar, a north point and dimensioned separation distances will be queried immediately.
Consultation with the regulator
The authority consults the Health and Safety Executive, and the environmental regulator where relevant. The Executive assesses the proposal using its own land use planning methodology, which considers the substance, the quantity, the containment and the distance to people, and then advises for or against.
That advice is not binding, but an authority granting consent against it is taking a visible risk, and in practice advice against is close to decisive. So engage before applying. Where the layout can be changed to increase separation distances, moving a vessel 20m across a yard at design stage is a great deal easier than arguing about it later.
Determination periods for these applications are set by the Regulations, and eight weeks is the familiar figure, extendable by agreement. Check the current Regulations, because the period and the fee are the two things most likely to have moved since any article was written.
Conditions and what happens afterwards
Consent can be granted with conditions, and the conditions are usually about quantity, location and the manner of keeping the substance. They bind whoever controls the land, which is the feature that catches new occupiers.
Two continuing obligations deserve attention. A change in the person in control of part of the land can revoke the consent unless an application for its continuation is made, so this belongs on the due diligence checklist for any sale, lease or assignment. And the authority has power to revoke or modify a consent in defined circumstances, with compensation provisions attached in some cases.
Where the holding changes, a fresh application or a variation is needed before the larger quantity arrives. Increasing a tank size or adding a second vessel is not a minor matter you can deal with at the next renewal, because there is no renewal cycle.
How it sits alongside planning permission
The two consents answer different questions and neither implies the other. You can hold planning permission for a building and have no consent for what you intend to store in it.
The relationship also runs the other way. Where you are proposing development near an existing hazardous installation, the authority consults the Health and Safety Executive about your scheme, and advice against development within a consultation distance is a serious obstacle for housing, schools and other sensitive uses. Check the consultation zones before buying land near an industrial site, and deal with the point in the Planning Statement rather than waiting for the consultee response, using the approach in our note on clearing a statutory consultee holding objection.
Where the description of development needs to change to reflect the substance holding, amending it after submission has its own procedure, as our guide to amending the description of development explains. And if the use itself relies on a prior approval route, the timing rules in prior approval applications and how the clock works apply to that element separately.
This is general guidance, not legal advice; check the position with your local planning 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
When is hazardous substances consent needed?
When a substance listed in the schedule to the Planning (Hazardous Substances) Regulations 2015 will be present on, over or under land at or above its controlled quantity. Presence is the trigger, not the process. Having the substance there without consent is an offence, and a planning permission for the building does not cover it.
How do the aggregation rules work?
Quantities of the same substance across the site are added together, and substances within the same hazard category are brought together under a summation rule, so several holdings each below the threshold can create a consent requirement. A small quantity at part of the site may be disregarded where it could not act as an initiator elsewhere.
Who is the hazardous substances authority?
Usually the district or unitary council. National Park authorities hold the function for land in a National Park, specified bodies hold it for certain statutory undertakers' operational land, and development corporations may hold it where the function has been conferred. Check the Act and Regulations, or ask the council's planning department, before applying.
Does the Health and Safety Executive decide the application?
No, the authority decides it, but the Executive is consulted and assesses the proposal using its land use planning methodology, looking at the substance, the quantity, the containment and the distance to people. Its advice is not binding, though advice against is close to decisive in practice, so engage before applying.
What happens to the consent if the site changes hands?
A change in the person in control of part of the land can revoke the consent unless an application for continuation is made, so it belongs on the due diligence list for any sale, lease or assignment. The authority also has power to revoke or modify a consent in defined circumstances, with compensation provisions in some cases.
Does consent cover an increase in the quantity stored?
Only up to the quantity consented and in the manner the conditions allow. Adding a vessel or increasing tank capacity needs a fresh application or a variation before the larger quantity arrives. There is no renewal cycle at which the point can be dealt with, so the change has to be applied for in advance.
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.