Environmental Risk Management: identifying what can go wrong, and what happens when it does.

It is the systematic identification of credible accident scenarios at a facility, estimation of their consequences and likelihood, and evaluation of whether the resulting risk is tolerable, followed by the specification of controls to prevent and mitigate them. It addresses abnormal events, whereas an Environment Management Plan addresses normal operation.

A site holding hazardous chemicals at or above the threshold quantities specified in the schedules to the Manufacture, Storage and Import of Hazardous Chemical Rules 1989. The designation triggers additional statutory duties including notification, safety reporting, an on-site emergency plan and defined information to be provided to workers and to the public. Whether a site crosses the threshold is a question of inventory against schedule, not of judgement.

The on-site emergency plan is prepared by the occupier and covers response within the installation boundary: alarm, evacuation, containment, medical response, mutual aid, rehearsal. The off-site plan covers the surrounding population and is prepared by the district authority under the applicable rules, using information the occupier supplies. The occupier owns one and feeds the other; assuming the district plan exists and is current is a common error.

For projects handling hazardous substances it usually is, the Terms of Reference commonly require a risk assessment and disaster management plan chapter, and the appraisal committee examines it. For projects without significant hazard the requirement may be limited. What the ToR grants determines the scope, so the point to resolve it is at scoping, not at report writing.

HAZOP is a structured qualitative technique that examines a process design node by node with guidewords to identify deviations and their causes and consequences. Quantitative risk assessment models specific scenarios numerically (release rates, dispersion, thermal radiation, overpressure) to produce consequence distances and risk figures. HAZOP finds what can go wrong; QRA estimates how bad and how likely. Serious sites need both.

The Public Liability Insurance Act 1991 requires owners handling hazardous substances above notified quantities to hold insurance providing immediate relief to persons affected by an accident involving those substances, on a no-fault basis, and to contribute to the Environment Relief Fund. It is a distinct obligation from consent conditions and is regularly overlooked by units that assume their general liability cover discharges it.

On change rather than on a fixed schedule: a new chemical, an inventory increase that crosses a threshold, a process or layout modification, a change in the surrounding land use that alters who is exposed, or a learning from an incident or near miss. In addition, emergency plans require periodic rehearsal and updating, and a risk assessment whose mitigation assumptions have not been tested in a drill is only partly verified.