Hazardous substances consent or an environmental permit

Hazardous substances consent and an environmental permit answer different questions about the same site. Consent is a planning authorisation for the presence of a dangerous substance above a controlled quantity on land, granted by the hazardous substances authority, which for most sites is your local planning authority. A permit is an operating authorisation for the activity and its emissions, granted by the Environment Agency or, for some air-emission activities, by the council's environmental protection team. If you are storing bulk LPG, ammonia or chlorine and also running a process that discharges to air or water, you may well need both, and neither substitutes for the other.

The mistake that costs time is assuming the permit application will pick up the storage question. It will not.

What each authorisation actually controls

Hazardous substances consent controls presence: which substance, in what quantity, where on the site, in what kind of container. It is granted under the Planning (Hazardous Substances) Act 1990 and the regulations made under it, runs with the land rather than with you, and is what allows the substance to be there at all. It does not regulate how you operate.

An environmental permit under the Environmental Permitting (England and Wales) Regulations 2016 controls operation: emission limits, monitoring, maintenance, competence of operators, incident reporting, site condition at surrender. It attaches to the operator and can be varied, transferred and surrendered.

Separate again is the major accident hazard regime for upper and lower tier establishments, where the Health and Safety Executive and the Environment Agency act together as the competent authority and safety reports and emergency plans are required. Falling into that regime is driven by the same substance quantities that trigger consent, so the thresholds are worth checking once, properly.

Substance thresholds that trigger consent

The regulations list named substances and categories of substance with a controlled quantity for each, and consent is needed where the quantity present, or capable of being present, reaches that figure. Aggregation rules apply, so several smaller vessels of the same substance count together, and mixture rules bring in substances that are dangerous by category rather than by name.

Three practical points:

• the test is the quantity that may be present, not the average holding, so design capacity matters
• storage and process inventory are counted together
• a change of substance, an increase in capacity or a new vessel can require a fresh application even where the site already has consent

Check the current schedule rather than a figure from an older guide, because the lists have been amended and the classification system they rely on has changed over time.

Consultation zones around a site

Where a site holds notifiable quantities, the Health and Safety Executive sets consultation distances around it, typically as inner, middle and outer zones. Those zones do not restrict the operator. They change how the planning system treats other people's development nearby: an application for housing, a school or a retail unit inside a zone triggers consultation with the executive, which advises the authority for or against the proposal according to the sensitivity of the use and its distance.

That has two consequences worth understanding before you apply. Your consent may attract objections from landowners whose development prospects the zones affect. And if you are the one proposing development near an existing installation, the zones explain the advice you are about to receive. Our note on hazardous substances consultation zones sets out how the advice is given.

Who regulates what

The executive is a consultee on consent applications rather than the decision maker, which surprises operators who have dealt with it in a health and safety context.

Applications and determination

A consent application goes to the hazardous substances authority with a description of the substance, the maximum quantity, a site plan showing where it will be kept, and the containers or vessels involved, together with the fee and the required publicity and certificates. The authority consults the executive and the Environment Agency and determines the application within the statutory period, commonly eight weeks, unless a longer period is agreed. Consent can be granted subject to conditions, and conditions on the location and containment of the substance are normal.

Permit applications run on a different timetable, with a duly-making stage, public consultation for some installations, and determination periods that vary by permit type. Bespoke permits take considerably longer than standard rules permits.

Where planning permission is also needed for the tanks, bunds or buildings, that is a third application. It can run in parallel, and the Planning Statement should explain the relationship between the three so the officer does not assume one covers the others.

Effect on neighbouring development, and on yours

Once consultation zones exist, nearby land becomes harder to develop for sensitive uses, and that can affect your own expansion plans as much as your neighbours'. Site layout is worth thinking about early: moving a bulk store 30 m can change which land falls within the inner zone.

Revocation is possible where the substance is no longer held, and consent can be modified. If you are acquiring a site, check what consent exists, for what quantity and subject to which conditions, because the consent runs with the land and an inherited condition you cannot meet is an enforcement risk from the day you complete.

Sequencing consent and permit

The order that works on most projects:

1. Establish the inventory and the maximum quantities, and test them against the controlled quantities and the major accident hazard thresholds.
2. Take pre-application advice from the hazardous substances authority, and speak to the executive about the likely consultation distances before the layout is fixed.
3. Apply for planning permission and hazardous substances consent together, so the layout and the substance location are considered as one scheme.
4. Apply for the environmental permit once the process design is settled, since emission limits depend on the plant specification.
5. Complete the major accident hazard notifications and reports on the statutory timetable, which is driven by the establishment's tier, not by the planning programme.

Two consents and a permit sounds heavy. On a site holding bulk hazardous substances it is the ordinary position, and discovering the second one late is what turns a six-month programme into eighteen months.

Where emissions to air rather than storage are the issue, an Air Quality Assessment and, for process odour, an Odour Assessment are the documents the planning side will ask for, and our comparison of air quality and odour assessments explains which does what.

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.