Safety breaches have explosive consequences

A magistrate has blasted a company after its use of explosives to clear the way for pipes in a housing estate resulted in a vehicle and worker being pelted in rock.

WorkSafe’s investigation of the 2007 incident at the Mernda Village housing estate, north of Melbourne, identified a litany of safety failings which could have caused a fatality.

Magistrate Roger Franich said the company was paid for its expertise in a specialised field and that it was unfortunate it took a serious incident to prompt safety improvements. He convicted and fined Impact Drilling $80,000 after it pleaded guilty to two charges laid under the Occupational Health and Safety Act.

The blasting was being carried out to prepare trenches for sewer lines because the land contained rock, but the court was told a blast management plan required by the Australian Standard was not produced and the shot firer was working outside his qualifications.

Blast management plans identify risks and hazards and what has to be done to mitigate them. They specify the proposed dates and times of blasting, warning procedures as well as details of traffic management plans and exclusion zones.

A number of workers were sent out of the blast zone before a series of charges were detonated, but communications between sentries, posted to prevent access to the site and the shot-firer, was inadequate. When an asphalt truck entered the area where blasting was to be done, a sentry drove out to warn the other driver, who immediately left the area.

WorkSafe’s investigation found the shot firer saw the asphalt truck leave, but that he could not see the entire blast zone because parts of it were obscured by piles of earth.

The charge was detonated without warning and flying rocks struck the sentry’s vehicle, about 55 m from the source of the explosion and smashing the windscreen. The utility driver who was walking back to it ran and was lucky (fortunate?) not to be hurt.

A WorkSafe inspector with 30 years' experience with explosives said an exclusion zone of 300 m was required for the work done that day.