On-Site Emergency Plan Preparation

A statutory document, not a formality

Sites holding hazardous chemicals above the notified threshold quantities must prepare an on-site emergency plan under the Manufacture, Storage and Import of Hazardous Chemical Rules. In practice that means most sites that qualify as MAH installations.

The plan is examined after an incident, and it is examined during inspections. What is looked at is not whether a document exists but whether it describes the plant as it is today and whether anybody has practised it.

The scenarios have to be real

The weakest plans we are asked to review share one flaw: the emergency scenarios were written from a template rather than derived from the plant. A plan that prepares for a fire the site cannot credibly have, while omitting the toxic release it can, protects nobody.

Credible scenarios come out of HAZOP and consequence and dispersion modelling, and the effect distances that follow decide the assembly points, the evacuation routes and who outside the fence needs warning.

What the plan has to carry

• Credible emergency scenarios with modelled effect distances.
• An incident command structure with named roles and deputies, workable on a night shift and not only on a weekday morning.
• Alarm, escalation and declaration criteria - who decides an emergency has begun.
• Assembly points, evacuation and escape route analysis, and headcount procedure.
• Firefighting, spill control and first aid resources, matched to the scenarios.
• Mutual aid arrangements and external notification lists, verified as current.
• Drill schedule, drill records and the review cycle.

Where plans fail

• Never updated after a modification. The most common finding.
• Contact lists gone stale - people who left, numbers that changed.
• Drills held but not recorded, or recorded without the learning points and what was fixed afterwards.
• Roles assigned to positions that operate on one shift only, leaving the structure hollow at night and at weekends.

We prepare plans, revise existing ones after modifications, and support drills. Where the underlying studies are missing we run those first, because the plan is only as good as the scenarios behind it.

Frequently Asked Questions

Who is required to have an on-site emergency plan?

Occupiers of sites holding hazardous chemicals above the notified threshold quantities - broadly, sites that qualify as Major Accident Hazard installations. The obligation sits with the occupier, and the plan has to be prepared before the activity starts and kept current afterwards.

What is the difference between the on-site and off-site plan?

The on-site plan is yours and covers everything inside the fence. The off-site plan is prepared by the district authority for the surrounding population, but it is built from the scenarios, quantities and consequence distances that you supply. A weak on-site plan produces a weak off-site plan.

How often should the plan be tested?

Mock drills are expected at regular intervals, and the record matters as much as the drill. An untested plan is treated as no plan during an inspection or an investigation, and the drill record is the first document asked for.

Does the plan need updating after a modification?

Yes. Any change to inventory, layout, process or protective systems can change which scenarios are credible and how far their effects reach. A plan describing a plant that no longer exists is a liability rather than a control.

Can you build the plan from our existing studies?

Usually. If a HAZOP, QRA or consequence analysis already exists, the credible scenarios and effect distances come straight from those. Where they do not exist, the modelling has to be done first - a plan written without it is guesswork about where the harm reaches.