The top tier of control for the largest hazardous-substance sites
Sites holding very large quantities of specified hazardous substances fall under the Major Hazard Facilities Regulations 2016, overseen by a specialist team at WorkSafe. A facility becomes an MHF when WorkSafe designates it after the operator notifies that it meets a threshold. There are two tiers: a lower tier MHF needs a major accident prevention policy, while an upper tier MHF must have a safety case formally accepted by WorkSafe and inform the local community.
All workplaces with hazardous substances must comply with the HSWA and the Hazardous Substances Regulations 2017. On top of that, sites that store or use large quantities of specified hazardous substances above set thresholds fall under the Major Hazard Facilities Regulations 2016. If a facility meets, or may meet, a threshold, the operator must notify WorkSafe and be assessed for designation as an MHF. A specialist WorkSafe team administers the regime.
| Tier | What it requires |
|---|---|
| Lower tier | Aggregated quantities at or above the lower threshold but below the upper. Must have a major accident prevention policy and manage major-incident risks. |
| Upper tier | Aggregated quantities at or above the upper threshold. Must conduct a safety assessment and have a safety case formally accepted by WorkSafe, and provide general information to the local community. |
WorkSafe can also use its discretion to designate a lower-tier facility as upper-tier where the risk is disproportionate or surrounding land use increases it.
An upper-tier safety case is a documented demonstration that the operator has identified all of its potential major incidents and has the ability and means to control them effectively — through safety-critical elements, a safety management system, and emergency planning. A “major incident” is an uncontrolled event involving specified hazardous substances that exposes multiple people to serious risk. Such failures are rare, but the consequences can be catastrophic.
The MHF regime builds on your wider hazardous substances management — your inventory and controls under the Hazardous Substances Regulations — and on strong emergency planning. Operators must also consult their territorial authority and inform the community.
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A site that stores or uses large quantities of specified hazardous substances above set thresholds, designated by WorkSafe under the Major Hazard Facilities Regulations 2016. The regime sits on top of the general Hazardous Substances Regulations.
If a facility meets, or may meet, a threshold quantity of a specified hazardous substance, the operator must notify WorkSafe. WorkSafe then assesses the notification and decides whether to designate the site as a lower or upper tier MHF.
It is the aggregated quantity of specified hazardous substances on site. A lower-tier MHF must have a major accident prevention policy; an upper-tier MHF must also conduct a safety assessment, have a safety case accepted by WorkSafe, and inform the local community.
A documented demonstration that an upper-tier operator has identified all of its potential major incidents and has the ability and means to control them effectively, through safety-critical elements, a safety management system and emergency planning.
An uncontrolled event at an MHF involving specified hazardous substances that exposes multiple people to a serious risk to health or safety. These are rare but can be catastrophic.
