Workplace Health and Safety Queensland issued an incident alert after an incident in February where a worker’s foot and ankle were injured when part of a three metre high near vertical excavation face collapsed.
There were four workers at the toe of the excavation when they heard a cracking sound and the excavation face collapsed. Three of them were able to jump out of the way but the fourth man was buried up to his knees. The safety regulator is currently conducting an investigation.
“Excavation failures are particularly dangerous because they can happen quickly, giving no chance for workers or others in the vicinity to escape, especially if the collapse is extensive,” WHSQ said in a statement.
“The speed of an excavation collapse increases the associated risks and the consequences are significant as falling earth can bury or crush people. This can result in suffocation or serious crush injuries.”
The agency urged PCBUs to establish the location of underground services before directing or allowing excavation work to start and to consider local site conditions; depth of excavation; soil properties; fractures or faults in rocks; any specialized plant or work methods required; the number of people involved; local weather conditions; and the effect of mobile plant close to the excavation.
The PCBU is also reminded that an emergency plan should be prepared for the workplace.
Control measures should also be in place if a worker must enter a trench where there is a risk of engulfment.
“Section 306 of the Work Health and Safety Regulation 2011 sets out requirements for trenches of at least 1.5 metres deep. Where shoring, benching or battering of the trench is not carried out, a geotechnical engineer must be engaged to assess the safety of the trench where the persons are required to enter the trench. However in the case of a bulk excavation (i.e. where only one excavated face poses a risk) the written advice of a geotechnical engineer may also be needed,” the alert says.
More information is available on Workplace Health and Safety Queensland’s website.
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