Explosive (Implosion) Demolition SWMS

Explosive (implosion) demolition is the felling of a structure by placing and initiating explosive charges so the building collapses into its own footprint. It is high risk construction work under the NSW WHS Regulation 2025 because it involves the demolition of load-bearing elements and the use of explosives (s291), so a SWMS is mandatory under s299, and a demolition licence applies. The blasting itself is carried out only by the holder of a blasting explosives user licence — a shotfirer — under the Explosives Act 2003 and Explosives Regulation 2013 (NSW), and the blast design, explosive selection, charge sizing, placement and initiation are determined and executed solely by that licensed shotfirer and are out of scope of this SWMS. What this SWMS governs is the workplace health and safety envelope around the implosion: the establishment and clearance of the danger zone, the control of flyrock and debris, the management of misfires, security of explosives and the site, the notification of authorities and neighbours, the monitoring of ground vibration and airblast against limits, and the controlled re-entry and post-blast clearance. The dominant hazards are flyrock striking people or property outside the intended zone, a misfire leaving live charges in an unstable structure, and the pressure and vibration of the blast itself. SafeWork NSW is the regulator for the WHS duties, and the document draws a clear line: the shotfirer owns the explosives engineering; the principal contractor owns the safety of everyone and everything around it.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Where the structure can be brought down mechanically without explosives, eliminate the blast entirely and demolish by conventional means
2. 2Substitution — Substitute a smaller, sequenced charge design (left to the licensed shotfirer) for a single large blast to reduce flyrock and vibration energy
3. 3Engineering — Danger-zone establishment with hard barricades, blast mats and protective screening to contain flyrock
4. 4Engineering — Ground-vibration and airblast monitoring at adjacent structures against defined peak-particle-velocity and overpressure limits
5. 5Engineering — Secure magazine storage and access control for all explosives on site
6. 6Administrative — Full danger-zone clearance and head-count sweep with an all-clear sign-off before initiation, controlled by the shotfirer and principal contractor
7. 7Administrative — Misfire procedure with a mandatory standdown time and no re-entry until the shotfirer declares the structure safe
8. 8Administrative — Notification of SafeWork NSW, police, emergency services and neighbours, with road and airspace closures as required
9. 9PPE — Hard hat, eye and hearing protection and high-visibility clothing for the exclusion-zone crew at the safe perimeter
10. 10PPE — Respiratory protection and eye protection for post-blast dust during inspection and clearance

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

By 5:00 am on blast day, a site manager from Cardinal Demolition has the danger zone established around a condemned grain tower: hard barricades on every approach, blast mats over the charge faces, and vibration monitors set at the two nearest buildings against agreed limits. The licensed shotfirer has completed charge placement the night before and now controls the firing sequence; the SWMS-driven task is to be certain no one is inside. The site manager runs a methodical head-count sweep with marshals on each sector, radioing all-clears that are logged against the entry register. Police hold the road closure and the rail corridor is confirmed clear with the operator. At the shotfirer's countdown, sirens sound the agreed signal, a final perimeter check is called, and the tower drops into its footprint. The crew holds position behind the barricades through the dust cloud and the mandatory standdown; only after the shotfirer inspects for any misfire and declares the rubble safe does re-entry begin, in respirators, to start the post-blast clearance.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS 2187.2 Explosives — Storage and use
• Demolition Work Code of Practice

Frequently asked questions